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1
Roxburgh, Lizanne. "The effect of gut processing on the quality of mistletoe seed dispersal". Journal of Tropical Ecology 23, n. 3 (24 aprile 2007): 377–80. http://dx.doi.org/10.1017/s0266467407004014.
Testo completoAbstract (sommario):
Disperser effectiveness is the contribution that a disperser makes to the future reproduction of a plant (Schupp 1993), and it has two components: quality and quantity of dispersal. Quantity of dispersal is a function of the number of visits that a disperser makes to a fruiting plant and the number of seeds that are dispersed during each visit. Quality of dispersal is a function of the treatment that a seed receives from its disperser and the site that the seed is finally deposited in. The quality of seed dispersal of the mistletoe Phragmanthera dschallensis (Engl.) M.G. Gilbert (Loranthaceae) by frugivorous birds was examined in this study.
2
Kamler, Jan F., Warren B. Ballard, Eric M. Gese, Robert L. Harrison e Seija M. Karki. "Dispersal characteristics of swift foxes". Canadian Journal of Zoology 82, n. 12 (1 dicembre 2004): 1837–42. http://dx.doi.org/10.1139/z04-187.
Testo completoAbstract (sommario):
From 1997 to 2001, we monitored movements of 109 adult and 114 juvenile swift foxes, Vulpes velox (Say, 1823), at study sites in Colorado, New Mexico, and Texas to determine patterns of dispersal. Significantly more male (93%) than female (58%) juveniles dispersed, and both sexes had similar bimodal dispersal patterns with peaks in September–October and January–February. Adult dispersal occurred more evenly throughout the year, and significantly more male (32%) than female (5%) adults dispersed. Adult males tended to disperse after the death of their mate. Of dispersing foxes with known fates, settlement percentages in new territories were similar between juvenile males and females (40% overall), but they were significantly lower than for adults (89%). All other dispersing foxes with known fates died. Among juvenile females with known fates, similar percentages of philopatric and dispersing foxes reproduced as yearlings (50% overall), so the benefits of dispersal versus philopatry were not clear. Although rarely reported for other species, adult males were an important dispersal cohort in swift foxes (43% of male dispersals and 25% of all dispersals). Because of the female-biased philopatry among swift foxes, dispersal of adult males likely decreased the chances for inbreeding (e.g., father–daughter breeding).
3
Lei, Boyu, Jifa Cui, Chris Newman, Christina D. Buesching, Zongqiang Xie, David W. Macdonald e Youbing Zhou. "Seed dispersers shape the pulp nutrients of fleshy-fruited plants". Proceedings of the Royal Society B: Biological Sciences 288, n. 1953 (23 giugno 2021): 20210817. http://dx.doi.org/10.1098/rspb.2021.0817.
Testo completoAbstract (sommario):
The dispersal-syndrome hypothesis posits that fruit traits are a product of selection by frugivores. Although criticized as adaptationist, recent studies have suggested that traits such as fruit or seed size, colour and odour exhibit signatures that imply selection by animal mutualists. These traits imply nutritional rewards (e.g. lipid, carbohydrate), attracting frugivores; however, this remains incompletely resolved. Here, we investigated whether fruit nutrients (lipid, sugar, protein, vitamin C, water content) moderate the co-adaptation of key disperser-group mutualisms. Multivariate techniques revealed that fruit nutrients assembled non-randomly and grouped according to key dispersal modes. Bird-dispersed fruits were richer in lipids than mammal-dispersed fruits. Mixed-dispersed fruits had significantly higher vitamin C than did mammal- or bird-dispersed fruits separately. Sugar and water content were consistently high irrespective of dispersal modes, suggesting that these traits appeal to both avian and mammalian frugivores to match high-energy requirements. Similarly, protein content was low irrespective of dispersal modes, corroborating that birds and mammals avoid protein-rich fruits, which are often associated with toxic levels of nitrogenous secondary compounds. Our results provide substantial over-arching evidence that seed disperser assemblages co-exert fundamental selection pressures on fruit nutrient trait adaptation, with broad implications for structuring fruit–frugivore mutualism and maintaining fruit trait diversity.
4
Just, Michael G., Wade A. Wall, Stacy D. Huskins e Matthew G. Hohmann. "Effects of Landscape Heterogeneity and Disperser Movement on Seed Dispersal". Ecologies 5, n. 2 (11 aprile 2024): 198–217. http://dx.doi.org/10.3390/ecologies5020013.
Testo completoAbstract (sommario):
The primacy of endozoochory for the maintenance and expansion of many woody plant populations is well known, but seed dispersal is not well understood for most species. This is especially true for rare species, where small population size and low fruit production can limit field- or observation-based experiments. Additionally, the effect of environmental heterogeneity on disperser movement is rarely investigated but has been shown to improve estimates of plant population spatial patterns and dynamics. We used simulation experiments to explore the effects of environmental heterogeneity and disperser movement on Lindera subcoriacea seed dispersal, a rare shrub from the southeastern United States with avian-dispersed seeds. Our experiments incorporated environmental heterogeneity and simulated disperser movement for five bird species, based on either landscape permeability or straight path rules. We anticipated that permeability-based movement would result in greater dispersal distances and seed dispersal effectiveness, which characterizes both quantity and quality. Generally, we did not find differences in seed dispersal between permeability and straight path experiments. However, we did find that permeability-based experiments had greater deposition into suitable habitat during flight (23 vs. 1%). These rare but longer distance depositions may be especially important for plants that are influenced by gap or interpopulation dynamics. We also found consistently greater dispersal into high quality habitats regardless of disperser species in permeability experiments, implying that incorporating species-specific assessments of landscape utilization (occupancy) could influence the effectiveness of seed dispersal. Our study suggests that including environmental heterogeneity in seed dispersal models can provide additional insights not provided by avian parameters (e.g., gut capacity, seed retention time, and flight speed) commonly used to inform dispersal models.
5
McLellan, Bruce N., e Frederick W. Hovey. "Natal dispersal of grizzly bears". Canadian Journal of Zoology 79, n. 5 (1 maggio 2001): 838–44. http://dx.doi.org/10.1139/z01-051.
Testo completoAbstract (sommario):
We studied natal dispersal of grizzly bears (Ursus arctos), a solitary nonterritorial carnivore with a promiscuous mating system, between 1979 and 1998. Dispersal distances for 2-year-olds did not differ between males and females, but by 3 years of age, males had dispersed farther than females, and farther still by 4 years of age. Dispersal of both sexes was a gradual process, occurring over 14 years. From the locations of death, or last annual ranges, it was estimated that 18 males dispersed 29.9 ± 3.5 km (mean ± SE) and 12 females dispersed 9.8 ± 1.6 km. Eleven of these males dispersed the equivalent of at least the diameter of 1 adult male home range, whereas only 3 of the females dispersed at least the diameter of 1 adult female home range. The longest dispersals recorded were 67 km for a male and 20 km for a female. Because the social system consists of numerous overlapping home ranges of both sexes, long dispersal distances may not be required to avoid inbreeding or competition with relatives. Simple models suggest that 61% of the ranges of brother and sister pairs would not overlap, but the home range of every daughter would overlap her father's range. The home range of an estimated 19 ± 4 (mean ± SD) adult males, however, would overlap at least a portion of each female's range, thereby reducing the chance of a female mating with her brother or father. Understanding the dispersal behaviour of grizzly bears is essential for developing conservation strategies. Our results suggest that meta-population reserve designs must provide corridors wide enough for male grizzly bears to live in with little risk of being killed.
6
Rehm, E., E. Fricke, J. Bender, J. Savidge e H. Rogers. "Animal movement drives variation in seed dispersal distance in a plant–animal network". Proceedings of the Royal Society B: Biological Sciences 286, n. 1894 (16 gennaio 2019): 20182007. http://dx.doi.org/10.1098/rspb.2018.2007.
Testo completoAbstract (sommario):
Frugivores play differing roles in shaping dispersal patterns yet seed dispersal distance is rarely quantified across entire communities. We model seed dispersal distance using gut passage times and bird movement for the majority (39 interactions) of known bird–tree interactions on the island of Saipan to highlight differences in seed dispersal distances provided by the five avian frugivores. One bird species was found to be a seed predator rather than a disperser. The remaining four avian species dispersed seeds but differences in seed dispersal distance were largely driven by interspecific variation in bird movement rather than intraspecific variation in gut passage times. The median dispersal distance was at least 56 m for all species-specific combinations, indicating all species play a role in reducing high seed mortality under the parent tree. However, one species—the Micronesian Starling—performed 94% of dispersal events greater than 500 m, suggesting this species could be a key driver of long-distance dispersal services (e.g. linking populations, colonizing new areas). Assessing variation in dispersal patterns across this network highlights key sources of variation in seed dispersal distances and suggests which empirical approaches are sufficient for modelling how seed dispersal mutualisms affect populations and communities.
7
van de Meutter, Frank, Robby Stoks e Luc de Meester. "Size-selective dispersal of Daphnia resting eggs by backswimmers ( Notonecta maculata )". Biology Letters 4, n. 5 (15 luglio 2008): 494–96. http://dx.doi.org/10.1098/rsbl.2008.0323.
Testo completoAbstract (sommario):
Freshwater zooplankton is increasingly used to study effects of dispersal on community and metacommunity structure. Yet, it remains unclear how zooplankton disperses. Clearly, birds and wind play a significant role as zooplankton dispersal agents, but they may not always be the main vectors. This experimental study shows that a cosmopolitan aquatic insect, Notonecta , can be an important vector of cladoceran resting eggs (ephippia). Dispersing Notonecta frequently transported ephippia during flight, with a bias towards smaller ephippia in two species. A similar trend was present at the species level: Daphnia species with smaller ephippia were more often dispersed, suggesting that Notonecta could generate specific colonist communities. In addition, buoyancy appeared a critical trait, as non-floating ephippia of Daphnia magna were never dispersed. Our data suggest that Notonecta could be important dispersers of Daphnia , and that knowledge of dispersal dynamics of Notonecta may be used to predict Daphnia dispersal, colonization and resilience to disturbance.
8
Moses, Kara L., e Stuart Semple. "Primary seed dispersal by the black-and-white ruffed lemur (Varecia variegata) in the Manombo forest, south-east Madagascar". Journal of Tropical Ecology 27, n. 5 (2 agosto 2011): 529–38. http://dx.doi.org/10.1017/s0266467411000198.
Testo completoAbstract (sommario):
Abstract:Seed dispersal is a pivotal ecological process but remains poorly understood on Madagascar, where lemurs are key dispersers. The black-and-white ruffed lemur (Varecia variegata) possesses many behavioural and ecological attributes potentially conducive to effective seed dispersal, but no studies have investigated dispersal patterns in this species. This 3-mo study quantified aspects of the primary seed dispersal patterns generated by two Varecia variegata groups (7 individuals). Feeding and ranging behaviour was quantified using behavioural observation (345.6 h), dispersal quantity and seed identity was determined by faecal analysis, and 10-wk germination trials tested effects of gut passage on germination of four species. Individual lemurs dispersed an estimated 104 seeds d−1, of 40 species. Most seeds were large (>10 mm); the largest was 42 mm long. Gut passage was rapid (mean 4.4 h) and generally increased germination speed and success. Mean and maximum inferred dispersal distances were 180 and 506 m respectively; low compared with many anthropoids, but possibly typical of lemurs. Though limited by a short study period, results suggest that the ruffed lemur is an effective disperser of seeds and possibly a critical disperser of large-seeded species which other frugivores cannot swallow. Loss of large-bodied seed dispersers such as Varecia variegata may have far-reaching ecological consequences including impacts on forest structure and dynamics.
9
Caughlin, T. Trevor, Jake M. Ferguson, Jeremy W. Lichstein, Pieter A. Zuidema, Sarayudh Bunyavejchewin e Douglas J. Levey. "Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages". Proceedings of the Royal Society B: Biological Sciences 282, n. 1798 (7 gennaio 2015): 20142095. http://dx.doi.org/10.1098/rspb.2014.2095.
Testo completoAbstract (sommario):
Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
10
Stevenson, Pablo, e Adriana Guzmán. "Seed dispersal, habitat selection and movement patterns in the Amazonian tortoise, Geochelone denticulata". Amphibia-Reptilia 29, n. 4 (2008): 463–72. http://dx.doi.org/10.1163/156853808786230442.
Testo completoAbstract (sommario):
AbstractThe Amazonian tortoise Geochelone denticulata may play an important role in forest dynamics due to its highly frugivorous diet, ability to disperse viable seeds, and predilection for resting in forest gaps for thermoregulation. The purpose of our study was to evaluate the species' effectiveness as a seed disperser. We measured dispersal quantity (abundance of seeds in feces, frequency of droppings, and population density of the disperser) and dispersal quality (movement patterns, habitat use, germination rates of dispersed seeds, and recruitment probabilities of seedlings) in a SW Amazonian forest, in Peru. Population density was calculated by mark-recapture and line-transect methods. Eight individuals were radio-tracked to monitor habitat use. Diet was described from fecal samples, which were washed to count seeds and for germination experiments. Seedling survival in different environmental conditions was monitored for three plant species. Population densities with mark-recapture estimates (0.15-0.31 individuals/ha) were much higher than with line transects estimates (0.0025 individuals/ha). Diet included fruit of 55 different plant species. Dispersed seeds had high germination rates (average 76%). In spite of their low activity, we documented long seed dispersal distances (average 89.6 m). Tortoises showed a marked preference for the open-canopy swampy forest, where long term recruitment was not favorable for seedlings of the species examined. However, the high solar radiation in this forest type promoted survival of pioneer seedlings in the short term. In conclusion, while G. denticulata did not perform a very efficient role in terms of the quantity of seed dispersal, the species can be considered efficient in many aspects of dispersal quality.
11
Longrich, Nicholas R., Jakob Vinther, R. Alexander Pyron, Davide Pisani e Jacques A. Gauthier. "Biogeography of worm lizards (Amphisbaenia) driven by end-Cretaceous mass extinction". Proceedings of the Royal Society B: Biological Sciences 282, n. 1806 (7 maggio 2015): 20143034. http://dx.doi.org/10.1098/rspb.2014.3034.
Testo completoAbstract (sommario):
Worm lizards (Amphisbaenia) are burrowing squamates that live as subterranean predators. Their underground existence should limit dispersal, yet they are widespread throughout the Americas, Europe and Africa. This pattern was traditionally explained by continental drift, but molecular clocks suggest a Cenozoic diversification, long after the break-up of Pangaea, implying dispersal. Here, we describe primitive amphisbaenians from the North American Palaeocene, including the oldest known amphisbaenian, and provide new and older molecular divergence estimates for the clade, showing that worm lizards originated in North America, then radiated and dispersed in the Palaeogene following the Cretaceous-Palaeogene (K-Pg) extinction. This scenario implies at least three trans-oceanic dispersals: from North America to Europe, from North America to Africa and from Africa to South America. Amphisbaenians provide a striking case study in biogeography, suggesting that the role of continental drift in biogeography may be overstated. Instead, these patterns support Darwin and Wallace's hypothesis that the geographical ranges of modern clades result from dispersal, including oceanic rafting. Mass extinctions may facilitate dispersal events by eliminating competitors and predators that would otherwise hinder establishment of dispersing populations, removing biotic barriers to dispersal.
12
Yu, Ren-Yong, e Peter C. Van Welzen. "Historical biogeography of Trigonostemon and Dimorphocalyx (Euphorbiaceae)". Botanical Journal of the Linnean Society 192, n. 2 (2 dicembre 2019): 333–49. http://dx.doi.org/10.1093/botlinnean/boz075.
Testo completoAbstract (sommario):
Abstract Trigonostemon and Dimorphocalyx are two morphologically similar genera in tropical Asia. We estimated their divergence times through a Bayesian clock analysis and reconstructed the historical biogeography using a likelihood analysis under the dispersal-extinction-cladogenesis (DEC) model and a statistical dispersal-vicariance analysis (S-DIVA). We have found that the two genera differ in their historical biogeography: Trigonostemon originated on the South-East Asian mainland, but one section dispersed to the Malay Peninsula and Borneo, where rapid speciation events occurred during the Pleistocene, whereas Dimorphocalyx originated on and extended to its current distribution from Borneo. The dispersal routes of both genera are well supported by the tectonic history and are comparable to the conclusions in previous case studies. Long-distance dispersals across Wallace’s line are of particular interest in biogeography. We compared the patterns of historical distribution and dispersal of our taxa and other comparable taxa in this area. Our data support the hypothesis that the Philippines is the most common stepping stone for crossing Wallace’s line. Furthermore, we consider that the frequent change of sea levels during the Pleistocene propelled the diversification of Trigonostemon section Trigonostemon in Borneo and the Malay Peninsula.
13
Hohmann, Matthew G., Wade A. Wall, Michael G. Just e Stacy D. Huskins. "Multiple intrinsic and extrinsic drivers influence the quantity and quality components of seed dispersal effectiveness in the rare shrub Lindera subcoriacea". PLOS ONE 18, n. 3 (31 marzo 2023): e0283810. http://dx.doi.org/10.1371/journal.pone.0283810.
Testo completoAbstract (sommario):
Information about seed dispersal effectiveness (SDE) for plant species of conservation concern is rarely available to inform management strategies and actions. For Lindera subcoriacea (bog spicebush, Lauraceae), a rare endemic dioecious shrub of the southeastern United States, we examined the influence of two intrinsic and five extrinsic drivers on the number and proportion of seeds either dispersed, or predated pre- and post-dispersal. The number of seeds dispersed characterizes the quantitative component of SDE, while pre- and post-dispersal seed predation can affect the qualitative component of SDE. Using fruit counts, seed traps, and seed removal depots over multiple years, we estimated that approximately 28% of L. subcoriacea seeds are lost to pre-dispersal predation, 69% of seeds are dispersed, 3% of seeds fail to disperse, and 65% of dispersed seeds are predated post-dispersal. We observed substantial variation in these three processes among individuals. We also found that both intrinsic (plant height, crop size) and extrinsic (understory cover, time since last fire, conspecific fruiting neighborhood, substrate) drivers differentially influenced the three processes. We identified four generalist, seasonally frugivorous, avian visitors at fruiting individuals that likely act as variably effective dispersers, while the Northern Cardinal (Cardinalis cardinalis L.) is a seed predator. Rodent granivores were important pre- and post-dispersal seed predators. The magnitude of our pre-dispersal and post-dispersal seed predation estimates suggest that, given the low fecundity of L. subcoriacea, conservation strategies should emphasize facilitating dispersal and reducing the effects of seed predation.
14
Tabassum, Samiya, e Stephen P. Bonser. "Allometry in the terminal velocity – dispersal architecture relationship explains variation in dispersal and offspring provisioning strategies in wind dispersed Asteraceae species". Australian Journal of Botany 65, n. 2 (2017): 149. http://dx.doi.org/10.1071/bt16180.
Testo completoAbstract (sommario):
Competition can simultaneously favour high dispersal ability (to transport offspring to more favourable habitats) and large seed size (to maximise offspring provisioning). In wind dispersed Asteraceae species, seeds are enclosed within an achene with hair-like projections from the achene form a pappus that acts as a parachute to aid in dispersal. There is potentially an allometric relationship between terminal velocity and pappus to achene volume ratio (dispersal architecture), with changes in dispersal architecture resulting in disproportionately high or low impacts on terminal velocity. We tested the hypothesis that competition induces shifts in dispersal architecture depending on the allometric relationship between terminal velocity and dispersal architecture. We estimated dispersal architecture of diaspores from seven wind dispersed Asteraceae species from environments with low and high neighbour densities. We also estimated diaspore terminal velocity for a subset of these species by recording drop time in a 2 m tube. Diaspores of one species had dispersal architecture promoting higher dispersal under high neighbour density, diaspores of two species had dispersal architecture promoting lower dispersal under high neighbour density, and dispersal architecture was not significantly different between high and low density environments for four of the species. Species showed a common allometric relationship between terminal velocity and dispersal architecture. The allometric relationship predicts dispersal architecture changes across environments differing in neighbour density. Species with dispersal architecture promoting higher dispersal under high neighbour density do so where small increases in dispersal architecture yield large decreases in terminal velocity. Our research suggests that the nature of allometric relationships between traits can help to explain allocation strategies across environments.
15
Sahley, Catherine Teresa, Klauss Cervantes, Edith Salas, Diego Paredes, Victor Pacheco e Alfonso Alonso. "Primary seed dispersal by a sigmodontine rodent assemblage in a Peruvian montane forest". Journal of Tropical Ecology 32, n. 2 (marzo 2016): 125–34. http://dx.doi.org/10.1017/s0266467416000043.
Testo completoAbstract (sommario):
Abstract:We examined quantity and quality components of primary seed dispersal for an assemblage of sigmodontine rodents in a high-elevation montane tropical forest in Peru. We collected faecal samples from 134 individuals belonging to seven rodent species from the subfamily Sigmodontinae (Cricetidae) over a 2-y period. We conducted seed viability tests for seeds found in faecal samples. We identified seeds from eight plant families (Bromeliaceae, Annonaceae, Brassicaceae, Ericaceae, Melastomatacae, Myrtaceae, Rosaceae, Solanaceae), nine genera and 13 morphospecies. The most abundant seeds belonged toGaultheriasp. 1 (46% of total) andMiconiasp. 1 (31% of total), while the most viable seeds belonged toGreigiasp. (84% viability) andGuatteriasp. (80% viability). We utilized relative rodent abundance, seed species diversity, seed abundance and seed viability per rodent species to calculate an index of rodent disperser effectiveness, and found thatThomasomys kalinowskiiwas the most effective disperser, followed byAkodon torques,Calomys sorellus,Thomasomys oreas,Oligoryzomys andinusandMicroryzomys minutus. Plant genera dispersed by sigmodontine rodents overlapped more with bird- and terrestrial-mammal-dispersed plants than with bat-dispersed plants. Future neotropical seed dispersal studies should consider small rodents as potential seed-dispersers, especially in tropical habitats where small-seeded, berry-forming shrubs and trees are present.
16
Condit, Richard, Brian Hatfield, Patricia A. Morris e Daniel P. Costa. "Quantifying dispersal between two colonies of northern elephant seals across 17 birth cohorts". PLOS ONE 18, n. 11 (30 novembre 2023): e0288921. http://dx.doi.org/10.1371/journal.pone.0288921.
Testo completoAbstract (sommario):
Dispersal drives extinction-recolonization dynamics of metapopulations and is necessary for endangered species to recolonize former ranges. Yet few studies quantify dispersal and even fewer examine consistency of dispersal over many years. The northern elephant seal (Mirounga angustirostris) provides an example of the importance of dispersal. It quickly recolonized its full range after near extirpation by 19th century hunting, and though dispersal was observed it was not quantified. Here we enumerate lifetime dispersal events among females marked as pups at two colonies during 1994-2010, then correct for detection biases to estimate bidirectional dispersal rates. An average of 16% of females born at the Piedras Blancas colony dispersed northward 200 km to breed at Año Nuevo, while 8.0% of those born at Año Nuevo dispersed southward to Piedras Blancas. The northward rate fluctuated considerably but was higher than southward in 15 of 17 cohorts. The population at Piedras Blancas expanded 15-fold during the study, while Año Nuevo’s declined slightly, but the expectation that seals would emigrate away from high density colonies was not supported. During the 1990s, dispersal was higher away from the small colony toward the large. Moreover, cohorts born later at Piedras Blancas, when the colony had grown, dispersed no more than early cohorts. Consistently high natal dispersal in northern elephant seals means the population must be considered a single large unit in terms of response to environmental change. High dispersal was fortuitous to the past recovery of the species, and continued dispersal means elephant seals will likely expand their range further.
17
Valdesolo, Tommaso, Silvia Del Vecchio e Gabriella Buffa. "Patterns of Seed Dispersal in Coastal Dune Plant Communities". Sustainability 14, n. 17 (2 settembre 2022): 10983. http://dx.doi.org/10.3390/su141710983.
Testo completoAbstract (sommario):
Seed dispersal is a key determinant of species distribution, although it is still unclear how it contributes to species assembly in plant communities. We linked patterns of seed dispersal to coexisting species to investigate the role of dispersal in the species assembly process. We focused on 19 species coexisting in a foredune plant community, classified as “foredune foundation species”, “semi-fixed dune species,” and “alien species”. The number of seeds dispersed by the 19 species was monitored monthly in 25 plots for 12 months. Then we compared both dispersal strategies and dispersal phenology among the species. Foredune foundation species, species of the semi-fixed dune, and alien species used the same dispersal strategies, with the exception of hemerochory, which was prevalently used by alien species. The three groups of species differentiated the dispersal season: semi-fixed dune species and alien species were early and late dispersers, respectively (spring vs. late summer), while foredune foundation species dispersed seeds in summer. Seasonal differentiation in seed dispersal may play a more important role in the species assembly process than dispersal vectors. Shifts in seasonality due to climate change may influence the timing of seed dispersal and provide species with different colonization opportunities.
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Pairon, Marie, Mathieu Jonard e Anne-Laure Jacquemart. "Modeling seed dispersal of black cherry, an invasive forest tree: how microsatellites may help?" Canadian Journal of Forest Research 36, n. 6 (1 giugno 2006): 1385–94. http://dx.doi.org/10.1139/x06-018.
Testo completoAbstract (sommario):
We used empirical models and three dispersal functions (Weibull, lognormal and 2Dt) to model seed distributions derived from the black cherry (Prunus serotina Ehrh.) understorey of a pine-dominated stand. Two different approaches were used to disentangle the overlapping seed shadows: the traditional inverse modeling approach and the genetic approach that uses microsatellite markers to assign a dispersed seed to its maternal parent. The distinction was made between the seeds passively dispersed by gravity (fruits with mesocarp) and those dispersed by birds (fruits without mesocarp). Our main objectives were to compare the three dispersal functions and assess the differences between the two approaches used. The functions performed equally well, but the lognormal function often showed a better data correlation. The best dispersal curves obtained by both traditional and genetic approaches were quite similar for the seeds dispersed by gravity, and 95% of these seeds were predicted to fall 5 and 3 m away from the parent tree for the traditional and genetic approaches, respectively. Differences were more important for the seeds dispersed by birds. The traditional approach predicted a lower number of seeds near the parent plant and a higher dispersal distance. Microsatellites provided accurate information on individual dispersal events and led to a better insight into the dispersal process.
19
GITHIRU, MWANGI, LEON BENNUN e LUC LENS. "Regeneration patterns among bird-dispersed plants in a fragmented Afrotropical forest, south-east Kenya". Journal of Tropical Ecology 18, n. 1 (gennaio 2002): 143–49. http://dx.doi.org/10.1017/s0266467402002092.
Testo completoAbstract (sommario):
Fruit-eating birds play an important role in the seed dispersal of many tropical plants (e.g. Herrera 1984), and the foraging behaviour of avian frugivores may affect their seed-dispersal capabilities (Loiselle & Blake 1999,Schupp 1993, Traveset 1994). For instance,shorter visits tend to produce less clumped seed distributions (Graham et al. 1995). Also,avian frugivores often feed on the fruits of several plant species over short periods of time (Herrera 1984, 1988a; Levey et al. 1994) in some non-random pattern (Herrera 1998). This potentially produces a predictable spatial pattern of the dispersed seeds (White & Stiles 1990). Forest destruction leads to fragmentation and degradation of the remaining habitats, which may influence patterns of adult tree distribution if the production, predation, dispersal, and/or regeneration of tree seeds is affected (Harrington et al. 1997). If dispersal of avian frugivores is disrupted by habitat fragmentation, plant species might face reduced regeneration, or even local extinction if they depend on a single, locally extinct disperser (Kellman et al. 1996). Increased predation of seeds and regenerating plants in the edges and gaps may also directly reduce regeneration rates (Corlett & Turner 1997, Harrington et al. 1997, Schupp 1988).
20
González-Varo, Juan P., Sarah Díaz-García, Juan M. Arroyo e Pedro Jordano. "Seed dispersal by dispersing juvenile animals: a source of functional connectivity in fragmented landscapes". Biology Letters 15, n. 7 (luglio 2019): 20190264. http://dx.doi.org/10.1098/rsbl.2019.0264.
Testo completoAbstract (sommario):
Juvenile animals generally disperse from their birthplace to their future breeding territories. In fragmented landscapes, habitat-specialist species must disperse through the anthropogenic matrix where remnant habitats are embedded. Here, we test the hypothesis that dispersing juvenile frugivores leave a footprint in the form of seed deposition through the matrix of fragmented landscapes. We focused on the Sardinian warbler ( Sylvia melanocephala ), a resident frugivorous passerine. We used data from field sampling of bird-dispersed seeds in the forest and matrix of a fragmented landscape, subsequent disperser identification through DNA-barcoding analysis, and data from a national bird-ringing programme. Seed dispersal by Sardinian warblers was confined to the forest most of the year, but warblers contributed a peak of seed-dispersal events in the matrix between July and October, mainly attributable to dispersing juveniles. Our study uniquely connects animal and plant dispersal, demonstrating that juveniles of habitat-specialist frugivores can provide mobile-link functions transiently, but in a seasonally predictable way.
21
Peña-Domene, Marinés, Cristina Martínez-Garza, Luz Ayestarán-Hernández e Henry Howe. "Plant Attributes that Drive Dispersal and Establishment Limitation in Tropical Agricultural Landscapes". Forests 9, n. 10 (10 ottobre 2018): 620. http://dx.doi.org/10.3390/f9100620.
Testo completoAbstract (sommario):
Factors that influence tropical-forest regeneration have been of interest across the tropics. We tested the degree of dispersal and establishment limitation of pioneer and non-pioneer tree species with different dispersal modes and seed sizes, using data on both seed fall and seedling establishment in primary forest, secondary forest, and pasture excluded from livestock. The study took place in a lowland tropical rain forest in southeastern Mexico. To calculate dispersal and establishment limitation, we used a density-weighted index that considers: (1) whether a seed or seedling of a given species has arrived in the sample area; and (2) the fraction of seeds or seedlings contributed by a given species relative to the total number of seeds or seedlings arriving at a sampling station. Dispersal limitation of non-pioneer species and animal-dispersed species decreased with succession. The secondary forest had less dispersal limitation for wind-dispersed pioneers than pasture, resulting in a dense aggregation of species with seeds dispersed by wind. Overall, establishment limitation differed between animal-dispersed and wind-dispersed species in the primary forest, and was negatively correlated with seed size. The low capacity of most species to arrive, germinate, and establish as seedlings in pastures slows succession back to forest. To overcome barriers to natural succession in pastures, transplanting seedlings of non-pioneer species is suggested because most of them show high dispersal and establishment limitation.
22
Fang, Gu, Xiao-Min Gao, Dong Zhang, Derek Dunn, Ruliang Pan, Bao-Guo Li e Xiao-Guang Qi. "Lengthy leader male tenure delays male offspring dispersal in a primate multilevel society". Behaviour 156, n. 13-14 (2019): 1371–91. http://dx.doi.org/10.1163/1568539x-00003570.
Testo completoAbstract (sommario):
Abstract Natal dispersals are male-biased in most Old World monkey species, especially those that are polygynous. We examined patterns of male dispersal in golden snub-nosed monkeys, in which male offspring mainly disperse as juveniles from their natal one-male units (OMUs) to a bachelor group. However, out of a total of 112 male dispersals from 2001–2016, we documented six cases in which male offspring remained in their natal OMU until sub-adulthood. Based on monitoring of dispersal dynamics, we found that male offspring were more likely to delay dispersal if the tenure of leader males was lengthy. Social network analysis showed male offspring who delayed dispersal exhibited strong social relationships with each other and their OMU leader male but not with the females of their OMU. Our results suggest that the length of leader male tenure may affect natal male dispersal due to benefits to leader males accrued via intrasexual competition and kin selection.
23
Simon, Thomas P., e Jacob L. Burskey. "Spatial Distribution and Dispersal Patterns of Central North American Freshwater Crayfish (Decapoda: Cambaridae) with Emphasis on Implications of Glacial Refugia". International Journal of Biodiversity 2014 (6 novembre 2014): 1–7. http://dx.doi.org/10.1155/2014/282079.
Testo completoAbstract (sommario):
Spatial distributions of crayfish were evaluated in relation to glacial geography and possible modes of dispersal from refugia. Species dispersal patterns were a priori hypothesized and tested using principle components analysis (PCA). PCA factor loading plots were evaluated for hypothesized crayfish dispersal patterns. Cambarus laevis was limited to the unglaciated region, while Orconectes immunis, Orconectes virilis, and Procambarus gracilis may have dispersed from western glacial refugia in the upper Missouri drainage. Fallicambarus fodiens and Procambarus acutus dispersed from south of the glacial advance within the Mississippi embayment. Previous dispersal hypotheses for Orconectes propinquus recognized that northern refugia may have been from the Driftless Area in Wisconsin and Illinois and may have invaded more than one refuge since this species was common in unglaciated areas of southwestern Indiana. Orconectes indianensis center of abundance is in the unglaciated region. Disjunct populations likely dispersed into temporary glacial lakes that, when receded, left populations in previously glaciated areas. Cambarus polychromatus possibly dispersed from southern refugia, while Cambarus sp. A cf. diogenes dispersed from southern refugia not sympatric with C. polychromatus. The glacial refugia included western and southern areas of the glacial maximum; however, northern dispersal routes may be important with global climate change.
24
Vangen, Knut Morten, Jens Persson, Arild Landa, Roy Andersen e Peter Segerström. "Characteristics of dispersal in wolverines". Canadian Journal of Zoology 79, n. 9 (1 settembre 2001): 1641–49. http://dx.doi.org/10.1139/z01-124.
Testo completoAbstract (sommario):
We studied patterns of dispersal and sizes of home ranges of juvenile wolverines (Gulo gulo). Mean dispersal age was 13 months for both male (n = 11) and female (n = 9) wolverines. Females displayed more variation in dispersal age (726 months) than males (718 months). Of the animals used in the dispersal analyses, all males and 69% of females dispersed. All sedentary females (n = 4) occupied their mother's territory when she died or shifted territory, and no females dispersed from a territory vacated by their mother. Competition for resources seemed to determine the female dispersal pattern, while competition for mates seemed to explain the male dispersal pattern. Dispersal distances averaged 51 km for males and 60 km for females. However, this is likely to be an underestimation. Eight cases of exploratory movements were observed, and on average, these immediately preceded dispersal movements. The size of juvenile home ranges of males (85 km2) and females (81 km2) corresponded to the home-range area of denning females during the summer period. Wolverines have the capacity to recolonize gaps in the present distribution of the species in Scandinavia. Other factors, therefore, most likely explain the large proportion of vacant wolverine habitats.
25
Kankam, Bright Obeng, e William Oduro. "Frugivores and fruit removal ofAntiaris toxicaria(Moraceae) at Bia Biosphere Reserve, Ghana". Journal of Tropical Ecology 25, n. 2 (marzo 2009): 201–4. http://dx.doi.org/10.1017/s0266467409005835.
Testo completoAbstract (sommario):
In tropical forests, most individual fruit-bearing trees depend on frugivores for seed dispersal (Howe & Smallwood 1982, Wilson 1992). Seed dispersal enhances germination potential, provides an opportunity for seeds to escape predation under the parent plants, and reduces seedling numbers under parent trees (Şekercioğluet al. 2004). The way frugivores handle seeds and process them may influence the seed fate of many plants (Janzen 1971). The quantity of seeds dispersed and the quality of dispersal provided by frugivores impact plant fitness (Herrera & Jordano 1981). Schupp (1993) defined the effectiveness of seed dispersal by frugivores as an empirical measure of quantity of seeds dispersed and quality of dispersal from the parent plant to a suitable microsite. Seed dispersal by frugivores increases the chances for seedling survival away from the vicinity of the parent plant because in tropical forests seed predation is concentrated under adult trees that prevent seedlings from establishing near parent trees (Howe & Miriti 2004).
26
Lönnell, Niklas, Veera Norros, Sebastian Sundberg, Üllar Rannik, Victor Johansson, Otso Ovaskainen e Kristoffer Hylander. "Testing a mechanistic dispersal model against a dispersal experiment with a wind-dispersed moss". Oikos 124, n. 9 (22 dicembre 2014): 1232–40. http://dx.doi.org/10.1111/oik.01886.
Testo completo
27
Palacio, Facundo Xavier. "Seed dispersal effectiveness by frugivorous birds: Identifying functional equivalent species in bird assemblages". Avian Biology Research 12, n. 3 (3 aprile 2019): 103–8. http://dx.doi.org/10.1177/1758155919832189.
Testo completoAbstract (sommario):
Seed dispersal by birds is a pivotal ecosystem function worldwide; yet, the rapid and ongoing global biodiversity loss poses a major threat to this essential ecosystem service. Seed dispersal effectiveness (SDE) is a key outcome of the interaction, represented by the product of seed dispersal quantity (number of seed dispersed) and quality (probability of recruitment of dispersed seeds). Therefore, identifying functional equivalent species in terms of SDE should become a key issue for bird conservation, since the effects of local extinctions on seed dispersal services may be weakened by remaining equivalent species. However, a method to quantitatively identify functional equivalent species in frugivorous bird assemblages is still lacking. To estimate SDE overlap between seed dispersers and assess whether two species may be functionally equivalent, I apply a novel nonparametric niche overlap index based on kernel functions and null models to test its statistical significance. For each bird species, I account for intraspecific variation in seed dispersal effectiveness to obtain a distribution of seed dispersal effectiveness values, an often neglected source of variation in seed dispersal assemblages. Non-significant differences in seed dispersal effectiveness overlap support the hypothesis that two species are functional equivalent, thus playing similar functional roles. The model proposed is applicable to any other quantity or quality component and is independent from the method or sampling design used to quantify SDE. The identification of functional equivalent species in seed dispersal assemblages adds to the theoretical framework of seed dispersal effectiveness and offers new insights into the ecology of the seed dispersal service provided by birds.
28
WÜTHERICH, DIRK, AURA AZÓCAR, CARLOS GARCÍA-NUÑEZ e JUAN F. SILVA. "Seed dispersal in Palicourea rigida, a common treelet species from neotropical savannas". Journal of Tropical Ecology 17, n. 3 (27 aprile 2001): 449–58. http://dx.doi.org/10.1017/s0266467401001304.
Testo completoAbstract (sommario):
The dispersal system of Palicourea rigida (Rubiaceae), a common woody species of neotropical savannas, was studied in a seasonal Venezuelan savanna. Production and consumption of fruits, dispersal agents, feeding behaviour, transport and effects on seed viability, were investigated by field observations, cage experiments and viability tests. To compare different dispersers, quantitative and qualitative dispersal parameters were calculated. About 59% of the fruit crop was dispersed successfully by birds. Although 10 different bird species consumed the fruits of Palicourea rigida, three bird species dispersed 79% of the fruits (Tyrannus melancholicus, Molothrus bonariensis and Elaenia chiriquensis). T. melancholicus (Tyrannidae) was the most important dispersal agent, with more than 39% of dispersed seeds. In contrast to the predictions of the specialization vs. generalization paradigm, this system achieves high effectiveness by means of predominantly unspecialized traits in both the plant and the dispersers.Se estudió el sistema de dispersión de Palicourea rigida (Rubiaceae), una leñosa común de las sabanas neotropicales, en una sabana estacional de Venezuela. Mediante observaciones de campo y experimentos en jaulas y en el laboratorio, se estudiaron paramétros tales como producción, transporte y consumo de frutos, los agentes dispersores y su comportamiento y los efectos sobre la viabilidad de las semillas. Para comparar los agentes de dispersión se estimaron paramétros cualitativos y cuantitativos. Cerca del 59% de la cosecha total de frutos fue dispersada existosamente por pájaros. Aunque los frutos fueron consumidos por diez especies de aves, el 79% de los frutos fueron dispersados por solamente tres especies (Tyrannus melancholicus, Molothrus bonariensis y Elaenia chiriquensis). T. melancholicus (Tyrannidae) fue el más importante agente dispersor con más del 39% del total de semillas dispersadas. En contraste con el paradigma de especialización vs. generalización, este sistema alcanza alta efectividad pero se caracteriza por rasgos poco especializados, tanto en la planta como en los dispersores.
29
Ghazoul, Jaboury. "Pollen and seed dispersal among dispersed plants". Biological Reviews 80, n. 03 (13 aprile 2005): 413. http://dx.doi.org/10.1017/s1464793105006731.
Testo completo
30
Farias, J., M. Sanchez, M. F. Abreu e F. Pedroni. "Seed dispersal and predation of Buchenavia tomentosa Eichler (Combretaceae) in a Cerrado sensu stricto, midwest Brazil". Brazilian Journal of Biology 75, n. 4 suppl 1 (24 novembre 2015): 88–96. http://dx.doi.org/10.1590/1519-6984.06214.
Testo completoAbstract (sommario):
Abstract The ecology of seed dispersal is critical to understand the patterns of distribution and abundance of plant species. We investigated seed dispersal aspects associated with the high abundance of Buchenavia tomentosa in the Serra Azul State Park (PESA). We estimated fruit production and conducted fruit removal experiments. We carried out diurnal and nocturnal observations on frugivory as well as germination tests. Fruiting occurred in the dry season and totaled 1,365,015 ± 762,670 fruits.ha–1. B. tomentosa fruits were utilized by eight animal species. The lowland tapir (Tapirus terrestris) was considered the main seed disperser. Leafcutter ants (Atta laevigata and Atta sexdens) participated in the seed cleaning and occasionally dispersed seeds. The beetle Amblycerus insuturatus, blue-and-yellow macaw (Ara ararauna) and red-and-green macaw (Ara chloropterus) were considered pre-dispersal seed predators. The seeds manually cleaned presented higher germination rate (100%) and speed index (4.2 seeds.d–1) than that of seeds with pulp. Germination of seeds found in tapirs’feces was 40%, while for the seeds without pulp it was 25%. The high abundance of B. tomentosa in the cerrado of PESA may be due to massive fruit production, low rates of seed predation, and efficient seed dispersal by tapirs, occurring before the rains which promote germination and recruitment of this species.
31
Catlin, D. H., D. K. Rosenberg e K. L. Haley. "The effects of nesting success and mate fidelity on breeding dispersal in burrowing owls". Canadian Journal of Zoology 83, n. 12 (1 dicembre 2005): 1574–80. http://dx.doi.org/10.1139/z05-154.
Testo completoAbstract (sommario):
Understanding and describing the factors that affect avian breeding dispersal are critical for modeling population dynamics and designing conservation strategies. We investigated the hypothesis that dispersal probability and dispersal distance are affected by nesting success and mate fidelity with band–resight data (1998–2003) from burrowing owls (Athene cunicularia (Molina, 1782)) nesting in southern California. Most owls (167 of 253, 66%) remained near their initial nest (<100 m), and those that moved >100 m dispersed 472 ± 65 m (mean ± 1 SE; n = 86). Both female and male owls whose nests failed were more likely to disperse and dispersed longer distances than owls with successful nests. Failed nesting attempts were also associated with an increased probability of divorce, and divorce was related to increased dispersal probabilities and distances. Moreover, female and male owls tended to be more likely to disperse and to disperse greater distances following the death of a mate than those that remained paired. Although dispersal was related to mate fidelity, nesting success remained an important factor affecting dispersal even after controlling for the effects of mate loss. Our results suggest that nesting failure was the primary factor associated with dispersal probability and dispersal distance in burrowing owls in our population.
32
Barroso, Judit, Dionisio Andújar, Carolina San Martín, César Fernández-Quintanilla e José Dorado. "Johnsongrass (Sorghum halepense) Seed Dispersal in Corn Crops under Mediterranean Conditions". Weed Science 60, n. 1 (marzo 2012): 34–41. http://dx.doi.org/10.1614/ws-d-11-00099.1.
Testo completoAbstract (sommario):
Natural dissemination of johnsongrass seeds as well as the effect of combine harvesting on this process were studied in corn fields. The estimation of natural dispersal was carried out by two different methods, collecting seeds throughout the season using seed traps and sampling soil–surface seed abundance before harvest using a vacuum device. Both methods showed the same dispersal pattern. A minimum of 84.6% was dispersed in the first 2 m from the focus and a maximum of 1.6% was dispersed beyond the first 5 m. An average of 76.3% of these dispersed seeds were lost or buried after shedding but before harvest. Seed dispersal by the combine harvester was estimated from the difference between soil–surface seed abundance in the same sites pre and postharvest. Although the quantity of seeds dispersed by the combine was similar to those dispersed by natural factors, dispersal distances were significantly higher. Around 90% of the dispersed seeds were found in the first 5 m forward and backward of the combine direction from the infestation source, and 1.6% of the seeds were found beyond 22 m forward and 10 m backward of the combine direction from the infestation source. A large proportion of the seeds dispersed were dormant or not viable. It is concluded that the major role of sexual reproduction in johnsongrass population dynamics may be to spread the risks, promoting dispersal in time and space.
33
Heleno, Ruben H., Jens M. Olesen, Manuel Nogales, Pablo Vargas e Anna Traveset. "Seed dispersal networks in the Galápagos and the consequences of alien plant invasions". Proceedings of the Royal Society B: Biological Sciences 280, n. 1750 (7 gennaio 2013): 20122112. http://dx.doi.org/10.1098/rspb.2012.2112.
Testo completoAbstract (sommario):
Alien plants are a growing threat to the Galápagos unique biota. We evaluated the impact of alien plants on eight seed dispersal networks from two islands of the archipelago. Nearly 10 000 intact seeds from 58 species were recovered from the droppings of 18 bird and reptile dispersers. The most dispersed invaders were Lantana camara , Rubus niveus and Psidium guajava , the latter two likely benefiting from an asynchronous fruit production with most native plants, which facilitate their consumption and spread. Lava lizards dispersed the seeds of 27 species, being the most important dispersers, followed by small ground finch, two mockingbirds, the giant tortoise and two insectivorous birds. Most animals dispersed alien seeds, but these formed a relatively small proportion of the interactions. Nevertheless, the integration of aliens was higher in the island that has been invaded for longest, suggesting a time-lag between alien plant introductions and their impacts on seed dispersal networks. Alien plants become more specialized with advancing invasion, favouring more simplified plant and disperser communities. However, only habitat type significantly affected the overall network structure. Alien plants were dispersed via two pathways: dry-fruited plants were preferentially dispersed by finches, while fleshy fruited species were mostly dispersed by other birds and reptiles.
34
Baker, F. A., e D. W. French. "Dispersal of Arceuthobiumpusillum seeds". Canadian Journal of Forest Research 16, n. 1 (1 febbraio 1986): 1–5. http://dx.doi.org/10.1139/x86-001.
Testo completoAbstract (sommario):
Seed dispersal of Arceuthobiumpusillum Peck on Piceamariana (Mill.) B.S.P. was studied at two locations in Minnesota from 1974–1980. Seed dispersal began as early as August 23 and was observed as late as September 27. Most seeds were dispersed in the mornings between 0400 and 0900. The mean annual distance of dispersal ranged from 1.0 to 2.3 m. The density of seeds trapped on the plots ranged from 4.2 to 16.7 seeds/m2. At both locations, the number of seeds trapped outside the stand decreased logarithmically with distance from the source trees. Within stands, seeds were more frequently trapped 1–4 m from source trees than under them. Most seed dispersal occurred 1-3 days after rain. Seeds were dispersed normally on 23 of 30 days when minimum temperatures were less than 0 °C. Fruit abortion was noted on four occasions. Insects were not found to carry dwarf mistletoe seeds.
35
Webb, Sara L. "Potential Role of Passenger Pigeons and Other Vertebrates in the Rapid Holocene Migrations of Nut Trees". Quaternary Research 26, n. 3 (novembre 1986): 367–75. http://dx.doi.org/10.1016/0033-5894(86)90096-7.
Testo completoAbstract (sommario):
Rapid rates of species range extension during the Holocene represent seed dispersal distances of at least 6 to 8 km per generation for North American species of Fagus, Quercus, and Carya, taxa whose fruits are heavy nuts. Occasional seed dispersal by biotic seed predators is necessary for these dispersal distances. One likely agent for dispersal across long distances and habitat discontinuities was the extinct (since 1914 A.D.) passenger pigeon (Ectopistes migratorius). This bird's abundance, capacity for delayed digestion, and nomadic habits strongly suggest an occasional seed dispersal role, although a coevolutionary seed dispersal relationship cannot be inferred from available evidence. The capacity of some heavy seeds for dispersal distances greater than those of most light, wind-dispersed seeds has biogeographic and genetic implications.
36
Park, Jeong-Soo, e Hyohyemi Lee. "Predicting the spatio-temporal distribution of the invasive alien plant Andropogon virginicus, in the South Korean peninsula considering long-distance dispersal capacities". PLOS ONE 18, n. 11 (14 novembre 2023): e0291365. http://dx.doi.org/10.1371/journal.pone.0291365.
Testo completoAbstract (sommario):
The spread of invasive alien species is a major threat to biodiversity. Estimating the long-distance dispersal capacity of invasive alien plants is vital for understanding their population dynamics and community composition. We predicted the spatial-temporal distribution of the alien plant Andropogon virginicus, in the Korean peninsula under climate change scenario using Random Forest (RF) and Cellular Automaton (CA) methods. Land use, barriers to dispersal, long-distance dispersal frequency, and maximum long-distance dispersal range were considered in our analysis. Our results showed that, among the five selected environmental variables, annual mean temperature and Human Foot-Printing (HFP) were positively associated with the occurrence probability of A. virginicus. This suggests that A. virginicus is likely to spread to the disturbed northern part of the Korean Peninsula due to climate change and habitat preference. When comparing modeling results for dispersal to field survey data, the modeling raster sets drawn from the long-distance dispersal frequency of 0.05 and maximum long-distance dispersal distance of 30 km y-1 had the most similar spatial expansion among the six long-distance dispersal parameter sets. The dispersal directions were associated with the landscape. Specifically, seeds dispersed by wind (anemochorous seeds) could propagate into open landscapes more easily than in forests. Regarding A. virginicus management, this grass can quickly invade bare ground with their wind-dispersed seeds, therefore habitat destruction, such as excessive logging and weeding, should be restrained.
37
Zhang, Zheng, Guangyue Wen, Dexiao Bu, Guojun Sun e Sheng Qiang. "Long−Distance Wind Dispersal Drives Population Range Expansion of Solidago canadensis". Plants 11, n. 20 (16 ottobre 2022): 2734. http://dx.doi.org/10.3390/plants11202734.
Testo completoAbstract (sommario):
Canada goldenrod (Solidago canadensis L.) is a serious invasive alien plant species that exerts negative effects on natural and agricultural ecosystems in China. Few studies have addressed the dispersal of S. canadensis to explain how it rapidly spreads to large areas over long distances. Here, we quantify the dispersal of S. canadensis via wind by capturing in situ−stained diaspores. The diaspores were trapped and counted along 11 radiating transects from the center of a dispersal source. Solidago canadensis diaspores could be dispersed in all directions from the source, traveling longer distances and in greater amounts in the downwind direction than the upwind one. With a source including about 58 million diaspores and a wind speed at Beaufort scale 4, the dispersal distance in the prevailing wind direction (PWD) was at least 2000 m. Diaspores shattered at a rate of approximately 3% daily with the common wind speed of scale 4, indicating that dispersal could last for more than a month. A mechanistic model was used to fit the dispersal curve along the PWD. Although the model slightly underestimated long−distance dispersal, it still demonstrated the potential of long−distance dispersal with great source strength. Wind−dispersed diaspores to new areas persisted over winter and were able to form new plants at a density of about 2 plants per m2 at 500 m away from the source. Further experiments showed that the dispersed amount of S. canadensis diaspores was significantly positively correlated with the temperature and wind speed, but significantly negatively correlated with relative humidity, which indicated that, during a day, the maximum dispersal usually occurred in the afternoon when the temperature was the highest and the relative humidity the lowest. In addition, for an already existent population patch, the patch range can expand 2−4 m per year, mainly depending on the seedlings recruited from the rhizomes. These results provide insights into the long−distance dispersal of S. canadensis by wind and its effects on the range expansion process.
38
Rost, J., J. M. Bas e P. Pons. "The importance of piled wood debris on the distribution of bird-dispersed plants in burned and logged Mediterranean pine forests". International Journal of Wildland Fire 21, n. 1 (2012): 79. http://dx.doi.org/10.1071/wf10068.
Testo completoAbstract (sommario):
Plant dispersal and colonisation are important processes in vegetation recovery after fire and, for several species, depend on the presence of frugivorous avian seed dispersers. In burned and salvage-logged Mediterranean pine forests, the occurrence of disperser birds is enhanced by the presence of wood debris piles built as erosion barriers, which become seed dispersal foci. We hypothesised that the distribution of bird-dispersed plants after fire could be determined by the presence of wood piles. We analysed the differences in species richness and overall cover of bird-dispersed plants, as well as the cover of the most common species, within piles and outside them. We also tested if micro-environmental conditions (slope orientation and pile size) might influence plant occurrence. We found more species and overall cover within piles, when located on southern and south-eastern slopes, than outside them. Moreover, taller piles showed higher values of bird-dispersed plant cover and richness. Therefore, wood piles may provide the necessary conditions for bird-dispersed plant recruitment in dry burned areas. To our knowledge, this is the first reported man-made structure that clearly benefits the recovery of bird-dispersed plants in burned areas, and suggests that piles may be a useful restoration measure when logging Mediterranean burned forests.
39
Hanson, Thor, Steven Brunsfeld, Bryan Finegan e Lisette Waits. "Conventional and genetic measures of seed dispersal for Dipteryx panamensis (Fabaceae) in continuous and fragmented Costa Rican rain forest". Journal of Tropical Ecology 23, n. 6 (29 ottobre 2007): 635–42. http://dx.doi.org/10.1017/s0266467407004488.
Testo completoAbstract (sommario):
The effects of habitat fragmentation on seed dispersal can strongly influence the evolutionary potential of tropical forest plant communities. Few studies have combined traditional methods and molecular tools for the analysis of dispersal in fragmented landscapes. Here seed dispersal distances were documented for the tree Dipteryx panamensis in continuous forest and two forest fragments in Costa Rica, Central America. Distance matrices were calculated between adult trees (n = 283) and the locations of seeds (n = 3016) encountered along 100 × 4-m transects (n = 77). There was no significant difference in the density of seeds dispersed > 25 m from the nearest adult (n = 253) among sites. There was a strong correlation between the locations of dispersed seeds and the locations of overstorey palms favoured as bat feeding roosts in continuous forest and both fragments. Exact dispersal distances were determined for a subset of seeds (n = 14) from which maternal endocarp DNA could be extracted and matched to maternal trees using microsatellite analysis. Dispersal within fragments and from pasture trees into adjacent fragments was documented, at a maximum distance of 853 m. Results show no evidence of a fragmentation effect on D. panamensis seed dispersal in this landscape and strongly suggest bat-mediated dispersal at all sites.
40
Takano, Tsubasa, Yohsuke Kominami e Hiromi Mizunaga. "Do Coarser Gap Mosaics in Conifer Plantations Induce More Seed Dispersal by Birds? Temporal Changes during 12 Years after Gap Creation". Forests 10, n. 10 (18 ottobre 2019): 918. http://dx.doi.org/10.3390/f10100918.
Testo completoAbstract (sommario):
The creation of canopy gaps is thought to be an efficient silvicultural operation to diversify species composition of monoculture conifer plantations; however, the shortage of regeneration materials in overclosed plantations is one of the concerns related to this operation. Seed dispersal by frugivorous birds may play an important role in inducing the spread of native broad-leaved trees in canopy gaps in plantations in the warm temperate zone of central Japan because bird-dispersed woody species are abundant in this area. We monitored the dynamics of the abundance and species composition of bird-dispersed seeds over 12 years after gap creation in the canopy of a Japanese cypress (Chamaecyparis obtusa (Siebold et Zucc.) Endl.) plantation. We also studied the effects of gap-mosaic patterns (from many small gaps to fewer large gaps) on dispersal. We used a hierarchical Bayesian zero-inflated Poisson model to analyze the factors affecting seed dispersal by frugivorous birds. Seed dispersal by birds increased with gap age except for just after gap creation. Dispersal in coarser gap mosaics was more abundant than that in finer gap mosaics. The species diversity of dispersed seeds in each seed trap (α-diversity) and plot (γ-diversity) showed similar trends in terms of temporal changes and differences between plots related to seed dispersal abundance; β-diversity did not. These trends might have been caused by shrub-vegetation development after gap creation. The effects of shrub vegetation were classified into the attraction by fruits borne within the vegetation, as well as other effects related to vegetation, such as functions of perch availability and insect presence as a food source. The presence of bird-dispersed seeds was strongly promoted by vegetation in all seasons, but only marginally by the presence of fruit-bearing vegetation. However, fruits attracted seed dispersal by frugivorous birds in the winter season. Our results suggest that both vegetation development and fruiting are important for promoting seed dispersal by frugivorous birds, and those effects are different in different seasons according to vegetation conditions and shifting food resources.
41
Cook, Carolyn A., Glen T. Hvenegaard, Geoffrey L. Holroyd, Hardy Pletz e Myrna Pearman. "Age and Sex Influence Natal and Breeding Dispersal of Purple Martins". Western Birds 52, n. 4 (1 novembre 2021): 296–310. http://dx.doi.org/10.21199/wb54.4.2.
Testo completoAbstract (sommario):
Dispersal patterns deepen our understanding of population dynamics. Dispersal by all age and sex classes enhances a species’ ability to respond to environmental changes, such as in habitat availability, artificial nest sites, and climate. The migration dynamics of the eastern subspecies of the Purple Martin (Progne subis subis) are well known, but we know less about its patterns of annual dispersal. We compared the frequency, distance, and direction of dispersal by each age/sex cohort of martins in central Alberta, at the northwestern limit of their breeding range. We used two datasets: (1) adult martins banded in central Alberta as nestlings and encountered during the summers of 2017 and 2018, and (2) records of encounters of banded martins in Canada from 1935 to 2016 from the Canadian Wildlife Service’s Bird Banding Office. In Alberta, 36% of birds dispersed from natal sites (by an average distance of 24 km), most commonly to the northeast. Across Canada, 29% of birds dispersed (by an average distance of 183 km), most commonly to the east and northeast. In Alberta, martins at least two years old dispersed less frequently than yearlings since some older martins returned to their natal site after first breeding elsewhere. Dispersal distances of after-second-year martins, which represent natal plus breeding dispersal, were greater than those of second-year birds, which represent natal dispersal alone. Thus some martins continue to disperse after their second year and do not maintain complete fidelity to a breeding site, which is different from our current understanding.
42
Taghizadeh, M. S., M. E. Nicolas e R. D. Cousens. "Effects of relative emergence time and water deficit on the timing of fruit dispersal in Raphanus raphanistrum L." Crop and Pasture Science 63, n. 10 (2012): 1018. http://dx.doi.org/10.1071/cp12246.
Testo completoAbstract (sommario):
Seed dispersal is both a spatial and a temporal phenomenon, although most studies focus on spatial aspects. Seed initiation on the maternal plant may occur over a considerable period, especially in indeterminately flowering species, and thus seeds may be exposed to a wide range of environmental conditions during their development. The result is variation in the timing of seed development, the anatomy of structures related to the dispersal process, and the behaviour and fate of seeds post-dispersal. A key resource during the growth and development of summer-maturing species in most areas, and one that is thus likely to modify these processes, is water. Two experiments were therefore undertaken to describe (i) the development of Raphanus raphanistrum fruits and the timing of fruit dispersal, and (ii) the effects of water availability on the timing of fruit dispersal. Fewer seeds were produced and subsequently dispersed by later emerging plants. The duration of fruit dispersal became shorter when the plants emerged progressively later than the crop, and the time of maximum dispersal was later. For cohorts of fruits initiated at the same time, those that developed under mild and severe water deficit reached their final length sooner, and were dispersed sooner, than those receiving a plentiful supply of water. Thus, the phenology of the maternal plant and the nature of its environment can modify the timing of propagule maturity and consequently dispersal. Such information may provide an opportunity for managers to reduce weed seed return to their field or, conversely, to regulate the amount of contaminated grain or reduce dispersal to other locations.
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Velázquez-Vázquez, Guadalupe, Arturo González-Zamora, Víctor Arroyo-Rodríguez e Joseph Taylor. "Seed dispersal by spider monkeys in logged and unlogged sites in the Calakmul tropical humid forest, Mexico / Dispersión de semillas por monos araña en sitios talados y no talados en el bosque húmedo tropical de Calakmul, México". Brazilian Journal of Animal and Environmental Research 5, n. 1 (21 gennaio 2022): 247–55. http://dx.doi.org/10.34188/bjaerv5n1-022.
Testo completoAbstract (sommario):
Seed dispersal by animals can be negatively affected by selective logging, but effects such changes in critical food resource, quality of food resources and food availability on seed dispersal and seedling recruitment, remains poorly understood. We investigated how selective logging, impacts the quantity of seed dispersal, focusing on highly frugivorous primate Ateles geoffroyi yucatanensis in Calakmul, Mexico. We assessed whether seed dispersal by the spider monkey differs between a logged and an unlogged site in the Calakmul tropical humid forest, Mexico. We recorded seeds in monkey faeces, including those deposited in latrines under sleeping trees (aggregated seed dispersal) and those dispersed across the forest (scattered seed dispersal) during a 5-mo period. The use of sleeping tree was similar in both forest conditions, averaging (± SD) 4.5 ± 4.3 weeks. They deposited 15,853 seeds (1–35 mm in length) from 20 tree species under sleeping trees, but seed abundance was 2.2 times higher in unlogged forests. Scattered seed dispersal (997 seeds from nine species) followed the opposite pattern, with 2.3 times more seeds in logged forests. The number of seeds and species per faecal sample did not differ between forest types, averaging 9.4 ± 20.2 seeds from 1.0 ± 0.8 seed species. Most (95%) scatter-dispersed seeds were undamaged in both forest types. These findings suggest that primate quantity seed dispersal is not limited in logged forests, potentially contributing to the recovery of these managed forests.
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Dematteis, Bruno, María S. Ferrucci e Juan P. Coulleri. "The evolution of dispersal traits based on diaspore features in South American populations of Senecio madagascariensis (Asteraceae)". Australian Journal of Botany 67, n. 4 (2019): 358. http://dx.doi.org/10.1071/bt18177.
Testo completoAbstract (sommario):
Plant invasion success is influenced by several driving factors such as the dispersal, environmental conditions and the species characteristics. In wind dispersed plants, the dispersal traits and the altitude are key for predicting dispersal ability. In this work, we estimated this feature in Senecio madagascariensis invasive populations from Argentina and Brazil using diaspore traits to understand its dynamics. Our results show that dispersal is strongly affected by the geographic conditions. We observed that in Argentinian populations growing at higher altitudes, selection favours larger seeds, which might favour seedling establishment over of longer dispersal distance. Conversely, populations grouped in lower altitudes show higher dispersal ability, probably due to the adaptation to environment and assortment of the better dispersal genotypes. In contrast, the Brazilian populations display rapid dispersal ability due to recent colonisation and multiple introductions. The variability in the gene pool could facilitate the occurrence of genotypes with greater dispersal, which could explain why these populations display greater dispersal ability than the Argentine ones. In conclusion, the phenotypic response to geographic conditions and the population density play an important role in the dispersion strategies in S. madagascariensis.
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Thomson, PC, K. Rose e NE Kok. "The behavioural ecology of dingoes in north-western Australia. VI. Temporary extraterritorial movements and dispersal". Wildlife Research 19, n. 5 (1992): 585. http://dx.doi.org/10.1071/wr9920585.
Testo completoAbstract (sommario):
Between 1975 and 1984, 105 radio-collared dingoes, Canis familiaris dingo, were tracked and observed from aircraft on the Fortescue River in Western Australia. Dingoes maintained strong site fidelity and seldom travelled far beyond their territories. In total, 81 forays (moves > 2km beyond territory boundaries) were identified from 6598 independent locations of pack members; 80 were < 10km from territory boundaries. Forays involved individuals as well as small groups; 68.2% of 22 confirmed individual forays were made by males. Forays occurred in all seasons and years. Some forays appeared to be related to subsequent dispersal. A total of 25 dingoes dispersed as solitary individuals. Mean dispersal distance beyond known pack territories was 20.1km (n = 19, range = 1-184 km). Males tended to disperse further than females and had a higher incidence of dispersal. Five groups of pack members and one entire pack also dispersed. The incidence of dispersal was highest when population density was high and food supply was low. Dispersal was facilitated by the availability of vacant areas. Humans caused much of the mortality of dispersing dingoes. The patterns of dispersal by individuals and groups, and the factors that influence them are similar for dingoes and the related canid, the wolf, Canis lupus. Control work in buffer zones must provide a satisfactory dispersal sink to minimise the risk of incursions by dingoes into livestock-grazing areas.
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van Hooff, Jan A. R. A. M., Erik P. Willems, Serge A. Wich e Elizabeth H. M. Sterck. "Female dispersal, inbreeding avoidance and mate choice in Thomas langurs (Presbytis thomasi)". Behaviour 142, n. 7 (2005): 845–68. http://dx.doi.org/10.1163/1568539055010093.
Testo completoAbstract (sommario):
AbstractFemale social dispersal in primates differs from the general mammalian pattern of locational dispersal. Both nulliparous and parous females may disperse to another group. Several hypotheses can explain female social dispersal: reduction of predation risk, inbreeding avoidance, and offspring protection through mate choice. We tested these hypotheses with an extended data set of Thomas langurs (Presbytis thomasi) and investigated parameters of male behaviour that females may use in their dispersal decisions. Data were collected over a 12.5-year period from a wild population in Sumatra, Indonesia, allowing for some critical tests of the hypotheses. Females dispersed to a group smaller than their original one, thereby refuting the predation risk hypothesis. Maturing nulliparous females only dispersed when their father was resident. Therefore, dispersal by nulliparous females was best explained through inbreeding avoidance. Parous females transferred to young, adult males. These males provided better protection to offspring against predation and infanticide than the old, late tenure males. Therefore, females transfer to better protector males. The male behavioural cues that females use to assess male quality were unclear. Females, however, may use proxies of male age, such as group composition and acoustical characteristics of loud calls, as indicators of male quality. The results suggest that female mate choice is an important function of social dispersal by parous females. Its importance in locational dispersal remains to be investigated.
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Brody, Alison K., e Kenneth B. Armitage. "The effects of adult removal on dispersal of yearling yellow-bellied marmots". Canadian Journal of Zoology 63, n. 11 (1 novembre 1985): 2560–64. http://dx.doi.org/10.1139/z85-381.
Testo completoAbstract (sommario):
The relative importance of adult–yearling interaction and individual behavioral phenotypes on dispersal of yearling yellow-bellied marmots was investigated. Two marmot colonies near Gothic, Colorado, were studied; one was treated as an experimental colony from which all adults were removed, while the second was left undisturbed. Analysis of dispersal patterns and behavioral observations indicated that agonistic behavior between adults and yearlings is not necessary for dispersal to occur. Dispersal of male yearlings appears to be independent of adult–yearling interactions, although dispersal of female yearlings probably is mediated by social interactions. Individual behavioral phenotypes could not be used to predict which animals dispersed nor the relative timing of their departure. Dispersal can be viewed as an important mating strategy; for yearling males it is likely to be the only option available for reproductive success.
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Haurez, Barbara, Kasso Daïnou, Nikki Tagg, Charles-Albert Petre e Jean-Louis Doucet. "The role of great apes in seed dispersal of the tropical forest tree species Dacryodes normandii (Burseraceae) in Gabon". Journal of Tropical Ecology 31, n. 5 (29 luglio 2015): 395–402. http://dx.doi.org/10.1017/s0266467415000322.
Testo completoAbstract (sommario):
Abstract:The identification of seed dispersers and predators is essential to understand the effect of anthropogenic disturbances, and the associated defaunation process, on tropical forest dynamics in Central Africa. In this study, the animals involved in seed predation and dispersal of Dacryodes normandii (Burseraceae), an endozoochorously dispersed tree species endemic to Gabonese forests, were identified in a site in south-east Gabon using two complementary methods: direct observation and camera-trap monitoring of fruit piles. The combined sampling effort (172 h of direct observations and 796 d of camera trapping) led to the identification of six disperser and eight predator species of D. normandii seeds. With high frequency of consumption (88% and 57% of their visits, respectively) and long visit duration (83 and 23 min, respectively), the western lowland gorilla and central chimpanzee were identified as the main dispersers of this species. Seeds passed through the gorilla gut exhibited high germination success (68%). Rodents were identified as predators of D. normandii seeds, potentially displaying rare secondary dispersal through scatter-hoarding. The results of this study highlight the importance of great apes in the seed dispersal of this tree species.
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Majer, Agnieszka, Alicja Laska, Gary Hein, Lechosław Kuczyński e Anna Skoracka. "Hitchhiking or hang gliding? Dispersal strategies of two cereal-feeding eriophyoid mite species". Experimental and Applied Acarology 85, n. 2-4 (5 ottobre 2021): 131–46. http://dx.doi.org/10.1007/s10493-021-00661-z.
Testo completoAbstract (sommario):
AbstractDispersal shapes the dynamics of populations, their genetic structure and species distribution; therefore, knowledge of an organisms’ dispersal abilities is crucial, especially in economically important and invasive species. In this study, we investigated dispersal strategies of two phytophagous eriophyoid mite species: Aceria tosichella (wheat curl mite, WCM) and Abacarus hystrix (cereal rust mite, CRM). Both species are obligatory plant parasites that infest cereals and are of economic significance. We investigated their dispersal success using different dispersal agents: wind and vectors. We hypothesised that in both mite species the main mode of dispersal is moving via wind, whereas phoretic dispersal is rather accidental, as the majority of eriophyoid mite species do not possess clear morphological or behavioural adaptations for phoresy. Results confirmed our predictions that both species dispersed mainly with wind currents. Additionally, WCM was found to have a higher dispersal success than CRM. Thus, this study contributes to our understanding of the high invasive potential of WCM.
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Majer, Agnieszka, Alicja Laska, Gary Hein, Lechosław Kuczyński e Anna Skoracka. "Hitchhiking or hang gliding? Dispersal strategies of two cereal-feeding eriophyoid mite species". Experimental and Applied Acarology 85, n. 2-4 (5 ottobre 2021): 131–46. http://dx.doi.org/10.1007/s10493-021-00661-z.
Testo completoAbstract (sommario):
AbstractDispersal shapes the dynamics of populations, their genetic structure and species distribution; therefore, knowledge of an organisms’ dispersal abilities is crucial, especially in economically important and invasive species. In this study, we investigated dispersal strategies of two phytophagous eriophyoid mite species: Aceria tosichella (wheat curl mite, WCM) and Abacarus hystrix (cereal rust mite, CRM). Both species are obligatory plant parasites that infest cereals and are of economic significance. We investigated their dispersal success using different dispersal agents: wind and vectors. We hypothesised that in both mite species the main mode of dispersal is moving via wind, whereas phoretic dispersal is rather accidental, as the majority of eriophyoid mite species do not possess clear morphological or behavioural adaptations for phoresy. Results confirmed our predictions that both species dispersed mainly with wind currents. Additionally, WCM was found to have a higher dispersal success than CRM. Thus, this study contributes to our understanding of the high invasive potential of WCM.