To see the other types of publications on this topic, follow the link: Ecological competition models.
Journal articles on the topic 'Ecological competition models'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Ecological competition models.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Kandler, Anne, and James Steele. "Ecological Models of Language Competition." Biological Theory 3, no. 2 (June 2008): 164–73. http://dx.doi.org/10.1162/biot.2008.3.2.164.
Full text
2
Mealey, Linda. "Evolutionary models of female intrasexual competition." Behavioral and Brain Sciences 22, no. 2 (April 1999): 234. http://dx.doi.org/10.1017/s0140525x99451817.
Full textAbstract:
Female competition generally takes nonviolent form, but includes intense verbal and nonverbal harassment that has profound social and physiological consequences. The evolutionary ecological model of competitive reproductive suppression in human females, might profitably be applied to explain a range of contemporary phenomena, including anorexia.
3
Jensen, A. L. "Simple models for exploitative and interference competition." Ecological Modelling 35, no. 1-2 (February 1987): 113–21. http://dx.doi.org/10.1016/0304-3800(87)90093-7.
Full text
4
Il’ichev, Vitaly G. "Analysis of competition models in periodic medium." Ecological Modelling 216, no. 2 (August 2008): 188–96. http://dx.doi.org/10.1016/j.ecolmodel.2008.03.007.
Full text
5
Haefner, James W., Geoffrey C. Poole, Patrick V. Dunn, and Richard T. Decker. "Edge effects in computer models of spatial competition." Ecological Modelling 56 (January 1991): 221–44. http://dx.doi.org/10.1016/0304-3800(91)90201-b.
Full text
6
van der Hoff, Quay, Johanna C. Greeff, and Temple H. Fay. "Defining a stability boundary for three species competition models." Ecological Modelling 220, no. 20 (October 2009): 2640–45. http://dx.doi.org/10.1016/j.ecolmodel.2009.07.027.
Full text
7
Good, Benjamin H., Stephen Martis, and Oskar Hallatschek. "Adaptation limits ecological diversification and promotes ecological tinkering during the competition for substitutable resources." Proceedings of the National Academy of Sciences 115, no. 44 (October 15, 2018): E10407—E10416. http://dx.doi.org/10.1073/pnas.1807530115.
Full textAbstract:
Microbial communities can evade competitive exclusion by diversifying into distinct ecological niches. This spontaneous diversification often occurs amid a backdrop of directional selection on other microbial traits, where competitive exclusion would normally apply. Yet despite their empirical relevance, little is known about how diversification and directional selection combine to determine the ecological and evolutionary dynamics within a community. To address this gap, we introduce a simple, empirically motivated model of eco-evolutionary feedback based on the competition for substitutable resources. Individuals acquire heritable mutations that alter resource uptake rates, either by shifting metabolic effort between resources or by increasing the overall growth rate. While these constitutively beneficial mutations are trivially favored to invade, we show that the accumulated fitness differences can dramatically influence the ecological structure and evolutionary dynamics that emerge within the community. Competition between ecological diversification and ongoing fitness evolution leads to a state of diversification–selection balance, in which the number of extant ecotypes can be pinned below the maximum capacity of the ecosystem, while the ecotype frequencies and genealogies are constantly in flux. Interestingly, we find that fitness differences generate emergent selection pressures to shift metabolic effort toward resources with lower effective competition, even in saturated ecosystems. We argue that similar dynamical features should emerge in a wide range of models with a mixture of directional and diversifying selection.
8
Griffiths, Jason I., Dylan Z. Childs, Ronald D. Bassar, Tim Coulson, David N. Reznick, and Mark Rees. "Individual differences determine the strength of ecological interactions." Proceedings of the National Academy of Sciences 117, no. 29 (July 6, 2020): 17068–73. http://dx.doi.org/10.1073/pnas.2000635117.
Full textAbstract:
Biotic interactions are central to both ecological and evolutionary dynamics. In the vast majority of empirical studies, the strength of intraspecific interactions is estimated by using simple measures of population size. Biologists have long known that these are crude metrics, with experiments and theory suggesting that interactions between individuals should depend on traits, such as body size. Despite this, it has been difficult to estimate the impact of traits on competitive ability from ecological field data, and this explains why the strength of biotic interactions has empirically been treated in a simplistic manner. Using long-term observational data from four different populations, we show that large Trinidadian guppies impose a significantly larger competitive pressure on conspecifics than individuals that are smaller; in other words, competition is asymmetric. When we incorporate this asymmetry into integral projection models, the predicted size structure is much closer to what we see in the field compared with models where competition is independent of body size. This difference in size structure translates into a twofold difference in reproductive output. This demonstrates how the nature of ecological interactions drives the size structure, which, in turn, will have important implications for both the ecological and evolutionary dynamics.
9
Lobry, Claude, Frédéric Mazenc, and Alain Rapaport. "Persistence in ecological models of competition for a single resource." Comptes Rendus Mathematique 340, no. 3 (February 2005): 199–204. http://dx.doi.org/10.1016/j.crma.2004.12.021.
Full text
10
Larsen, Lawrence C., and William A. Williams. "Fitting De Wit competition models with general nonlinear regression programs." Ecological Modelling 41, no. 1-2 (April 1988): 147–50. http://dx.doi.org/10.1016/0304-3800(88)90051-8.
Full text
11
Ursell, Tristan. "Structured environments foster competitor coexistence by manipulating interspecies interfaces." PLOS Computational Biology 17, no. 1 (January 7, 2021): e1007762. http://dx.doi.org/10.1371/journal.pcbi.1007762.
Full textAbstract:
Natural environments, like soils or the mammalian gut, frequently contain microbial consortia competing within a niche, wherein many species contain genetically encoded mechanisms of interspecies competition. Recent computational work suggests that physical structures in the environment can stabilize local competition between species that would otherwise be subject to competitive exclusion under isotropic conditions. Here we employ Lotka-Volterra models to show that interfacial competition localizes to physical structures, stabilizing competitive ecological networks of many species, even with significant differences in the strength of competitive interactions between species. Within a limited range of parameter space, we show that for stable communities the length-scale of physical structure inversely correlates with the width of the distribution of competitive fitness, such that physical environments with finer structure can sustain a broader spectrum of interspecific competition. These results highlight the potentially stabilizing effects of physical structure on microbial communities and lay groundwork for engineering structures that stabilize and/or select for diverse communities of ecological, medical, or industrial utility.
12
Ursell, Tristan. "Structured environments foster competitor coexistence by manipulating interspecies interfaces." PLOS Computational Biology 17, no. 1 (January 7, 2021): e1007762. http://dx.doi.org/10.1371/journal.pcbi.1007762.
Full textAbstract:
Natural environments, like soils or the mammalian gut, frequently contain microbial consortia competing within a niche, wherein many species contain genetically encoded mechanisms of interspecies competition. Recent computational work suggests that physical structures in the environment can stabilize local competition between species that would otherwise be subject to competitive exclusion under isotropic conditions. Here we employ Lotka-Volterra models to show that interfacial competition localizes to physical structures, stabilizing competitive ecological networks of many species, even with significant differences in the strength of competitive interactions between species. Within a limited range of parameter space, we show that for stable communities the length-scale of physical structure inversely correlates with the width of the distribution of competitive fitness, such that physical environments with finer structure can sustain a broader spectrum of interspecific competition. These results highlight the potentially stabilizing effects of physical structure on microbial communities and lay groundwork for engineering structures that stabilize and/or select for diverse communities of ecological, medical, or industrial utility.
13
Bravo de la Parra, R., M. Marvá, E. Sánchez, and L. Sanz. "Discrete Models of Disease and Competition." Discrete Dynamics in Nature and Society 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/5310837.
Full textAbstract:
The aim of this work is to analyze the influence of the fast development of a disease on competition dynamics. To this end we present two discrete time ecoepidemic models. The first one corresponds to the case of one parasite affecting demography and intraspecific competition in a single host, whereas the second one contemplates the more complex case of competition between two different species, one of which is infected by the parasite. We carry out a complete mathematical analysis of the asymptotic behavior of the solutions of the corresponding systems of difference equations and derive interesting ecological information about the influence of a disease in competition dynamics. This includes an assessment of the impact of the disease on the equilibrium population of both species as well as some counterintuitive behaviors in which although we would expect the outbreak of the disease to negatively affect the infected species, the contrary happens.
14
Cale, W. G., and R. V. O'Neill. "Aggregation and consistency problems in theoretical models of exploitative resource competition." Ecological Modelling 40, no. 2 (February 1988): 97–109. http://dx.doi.org/10.1016/0304-3800(88)90105-6.
Full text
15
UPADHYAY, RANJIT KUMAR. "OBSERVABILITY OF CHAOS AND CYCLES IN ECOLOGICAL SYSTEMS: LESSONS FROM PREDATOR–PREY MODELS." International Journal of Bifurcation and Chaos 19, no. 10 (October 2009): 3169–234. http://dx.doi.org/10.1142/s0218127409024748.
Full textAbstract:
We examine and assess deterministic chaos as an observable. First, we present the development of model ecological systems. We illustrate how to apply the Kolmogorov theorem to obtain limits on the parameters in the system, which assure the existence of either stable equilibrium point or stable limit cycle behavior in the phase space of two-dimensional (2D) dynamical systems. We also illustrate the method of deriving conditions using the linear stability analysis. We apply these procedures on some basic existing model ecological systems. Then, we propose four model ecological systems to study the dynamical chaos (chaos and intermittent chaos) and cycles. Dynamics of two predation and two competition models have been explored. The predation models have been designed by linking two predator–prey communities, which differ from one another in one essential way: the predator in the first is specialist and that in the second is generalist. The two competition models pertain to two distinct competition processes: interference and exploitative competition. The first competition model was designed by linking two predator–prey communities through inter-specific competition. The other competition model assumes that a cycling predator–prey community is successfully invaded by a predator with linear functional response and coexists with the community as a result of differences in the functional responses of the two predators. The main criterion behind the selection of these two model systems for the present study was that they represent diversity of ecological interactions in the real world in a manner which preserves mathematical tractability. For investigating the dynamic behavior of the model systems, the following tools are used: (i) calculation of the basin boundary structures, (ii) performing two-dimensional parameter scans using two of the parameters in the system as base variables, (iii) drawing the bifurcation diagrams, and (iv) performing time series analysis and drawing the phase space diagrams. The results of numerical simulation are used to distinguish between chaotic and cyclic behaviors of the systems.The conclusion that we obtain from the first two model systems (predation models) is that it would be difficult to capture chaos in the wild because ecological systems appear to change their attractors in response to changes in the system parameters quite frequently. The detection of chaos in the real data does not seem to be a possibility as what is present in ecological systems is not robust chaos but short-term recurrent chaos. The first competition model (interference competition) shares this conclusion with those of predation ones. The model with exploitative competition suggests that deterministic chaos may be robust in certain systems, but it would not be observed as the constituent populations frequently execute excursions to extinction-sized densities. Thus, no matter how good the data characteristics and analysis techniques are, dynamical chaos may continue to elude ecologists. On the other hand, the models suggest that the observation of cyclical dynamics in nature is the most likely outcome.
16
Phillips, P. D., I. S. Thompson, J. N. M. Silva, P. R. van Gardingen, and B. Degen. "Scaling up models of tree competition for tropical forest population genetics simulation." Ecological Modelling 180, no. 2-3 (December 2004): 419–34. http://dx.doi.org/10.1016/j.ecolmodel.2004.04.029.
Full text
17
Hernández, Mariano Agustín, Juan Adolfo López, and Eduardo Pablo Cappa. "Improving Genetic Analysis of Corymbia citriodora subsp. variegata with Single- and Multiple-Trait Spatial-Competition Models." Forest Science 65, no. 5 (August 30, 2019): 570–80. http://dx.doi.org/10.1093/forsci/fxz020.
Full textAbstract:
Abstract Environmental heterogeneity and/or genetic and environmental competition were quantified on two growth traits, diameter at breast height and total height, and wood density in a progeny trial of Corymbia citriodora subsp. variegata. Three single-trait mixed models with random spatial and/or competition effects were compared to a standard analysis by analyzing fit, dispersion parameters, accuracy of breeding values, genetic gains, and ranking of trees. In addition, a multiple-trait spatial-competition model was fitted to estimate correlations among direct and indirect additive genetic effects, and to explore relations between traits. Single-trait analyses with spatial and/or competition effects outperformed the standard model. However, the performance of these models depended on the sensitivity of each trait to detect each effect. Direct–indirect genetic correlations from the multiple-trait spatial-competition model showed inverse and strong relations among growth traits and wood density, suggesting that growth traits can be affected by competition and environmental heterogeneity, but also wood density might be influenced by these effects. The approach proposed was useful to improve the genetic analysis of the species as well as to gain an understanding of the genetic relations between traits under the influence of environmental heterogeneity and competition.
18
Paton, Robert S., and Michael B. Bonsall. "The ecological and epidemiological consequences of reproductive interference between the vectors Aedes aegypti and Aedes albopictus." Journal of The Royal Society Interface 16, no. 156 (July 2019): 20190270. http://dx.doi.org/10.1098/rsif.2019.0270.
Full textAbstract:
Vector ecology is integral to understanding the transmission of vector-borne diseases, with processes such as reproduction and competition pivotal in determining vector presence and abundance. The arbovirus vectors Aedes aegypti and Aedes albopictus compete as larvae, but this mechanism is insufficient to explain patterns of coexistence and exclusion. Inviable interspecies matings—known as reproductive interference—is another candidate mechanism. Here, we analyse mathematical models of mosquito population dynamics and epidemiology which include two Aedes -specific features of reproductive interference. First, as these mosquitoes use hosts to find mates, reproductive interference will only occur if the same host is visited. Host choice will, in turn, be determined by behavioural responses to host availability. Second, females can become sterilized after mis-mating with heterospecifics. We find that a species with an affinity for a shared host will suffer more from reproductive interference than a less selective competitor. Costs from reproductive interference can be ‘traded-off’ against costs from larval competition, leading to competitive outcomes that are difficult to predict from empirical evidence. Sterilizations of a self-limiting species can counterintuitively lead to higher densities than a competitor suffering less sterilization. We identify that behavioural responses and reproductive interference mediate a concomitant relationship between vector ecological dynamics and epidemiology. Competitors with opposite behavioural responses can maintain disease where human hosts are rare, due to vector coexistence facilitated by a reduced cost from reproductive interference. Our work elucidates the relative roles of the competitive mechanisms governing Aedes populations and the associated epidemiological consequences.
19
Kropff, M. J., and L. A. P. Lotz. "Optimization of Weed Management Systems: The Role of Ecological Models of Interplant Competition." Weed Technology 6, no. 2 (June 1992): 462–70. http://dx.doi.org/10.1017/s0890037x00035065.
Full textAbstract:
The strategy to optimize weed management systems with a minimum use of herbicides includes both the adaptation of crop management practices and well designed decision making systems, based on postemergence observations of weed infestations. Both strategies require thorough quantitative insight into the crop weed ecosystem, which can be provided by systems analysis, using process based models. These models also can be applied to similar systems like intercropping. For practical application, however, a simple measure of weed infestation and a simple model which relates weed infestation to yield loss are required. Recent progress in model development is discussed. An alternative empirical model that predicts yield loss from the relative leaf area of the weeds shortly after crop emergence, seems to be a useful approach for prediction of yield loss shortly after crop emergence. The use of systems approaches at different levels of detail for bridging the gap between research and practical application is discussed.
20
Vandermeer, John. "Coupled Oscillations in Food Webs: Balancing Competition and Mutualism in Simple Ecological Models." American Naturalist 163, no. 6 (June 2004): 857–67. http://dx.doi.org/10.1086/420776.
Full text
21
Martínez-García, Ricardo, Justin M. Calabrese, Emilio Hernández-García, and Cristóbal López. "Minimal mechanisms for vegetation patterns in semiarid regions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2027 (October 28, 2014): 20140068. http://dx.doi.org/10.1098/rsta.2014.0068.
Full textAbstract:
The minimal ecological requirements for the fomation of regular vegetation patterns in semiarid systems have been recently questioned. Against the general belief that a combination of facilitative and competitive interactions is necessary, recent theoretical studies suggest that, under broad conditions, non-local competition among plants alone may induce patterns. In this paper, we review results along this line, presenting a series of models that yield spatial patterns when finite-range competition is the only driving force. A preliminary derivation of this type of model from a more detailed one that considers water–biomass dynamics is also presented.
22
Martin, Benjamin T., Stephan B. Munch, and Andrew M. Hein. "Reverse-engineering ecological theory from data." Proceedings of the Royal Society B: Biological Sciences 285, no. 1878 (May 16, 2018): 20180422. http://dx.doi.org/10.1098/rspb.2018.0422.
Full textAbstract:
Ecologists have long sought to understand the dynamics of populations and communities by deriving mathematical theory from first principles. Theoretical models often take the form of dynamical equations that comprise the ecological processes (e.g. competition, predation) believed to govern system dynamics. The inverse of this approach—inferring which processes and ecological interactions drive observed dynamics—remains an open problem in ecology. Here, we propose a way to attack this problem using a machine learning method known as symbolic regression, which seeks to discover relationships in time-series data and to express those relationships using dynamical equations. We found that this method could rapidly discover models that explained most of the variance in three classic demographic time series. More importantly, it reverse-engineered the models previously proposed by theoretical ecologists to describe these time series, capturing the core ecological processes these models describe and their functional forms. Our findings suggest a potentially powerful new way to merge theory development and data analysis.
23
Pontarp, Mikael, and Owen L. Petchey. "Community trait overdispersion due to trophic interactions: concerns for assembly process inference." Proceedings of the Royal Society B: Biological Sciences 283, no. 1840 (October 12, 2016): 20161729. http://dx.doi.org/10.1098/rspb.2016.1729.
Full textAbstract:
The expected link between competitive exclusion and community trait overdispersion has been used to infer competition in local communities, and trait clustering has been interpreted as habitat filtering. Such community assembly process inference has received criticism for ignoring trophic interactions, as competition and trophic interactions might create similar trait patterns. While other theoretical studies have generally demonstrated the importance of predation for coexistence, ours provides the first quantitative demonstration of such effects on assembly process inference, using a trait-based ecological model to simulate the assembly of a competitive primary consumer community with and without the influence of trophic interactions. We quantified and contrasted trait dispersion/clustering of the competitive communities with the absence and presence of secondary consumers. Trophic interactions most often decreased trait clustering (i.e. increased dispersion) in the competitive communities due to evenly distributed invasions of secondary consumers and subsequent competitor extinctions over trait space. Furthermore, effects of trophic interactions were somewhat dependent on model parameters and clustering metric. These effects create considerable problems for process inference from trait distributions; one potential solution is to use more process-based and inclusive models in inference.
24
Damgaard, Christian. "Integrating Hierarchical Statistical Models and Machine-Learning Algorithms for Ground-Truthing Drone Images of the Vegetation: Taxonomy, Abundance and Population Ecological Models." Remote Sensing 13, no. 6 (March 18, 2021): 1161. http://dx.doi.org/10.3390/rs13061161.
Full textAbstract:
In order to fit population ecological models, e.g., plant competition models, to new drone-aided image data, we need to develop statistical models that may take the new type of measurement uncertainty when applying machine-learning algorithms into account and quantify its importance for statistical inferences and ecological predictions. Here, it is proposed to quantify the uncertainty and bias of image predicted plant taxonomy and abundance in a hierarchical statistical model that is linked to ground-truth data obtained by the pin-point method. It is critical that the error rate in the species identification process is minimized when the image data are fitted to the population ecological models, and several avenues for reaching this objective are discussed. The outlined method to statistically model known sources of uncertainty when applying machine-learning algorithms may be relevant for other applied scientific disciplines.
25
Sieber, Michael, Horst Malchow, and Frank M. Hilker. "Disease-induced modification of prey competition in eco-epidemiological models." Ecological Complexity 18 (June 2014): 74–82. http://dx.doi.org/10.1016/j.ecocom.2013.06.002.
Full text
26
Bausman, William. "The Aims and Structures of Ecological Research Programs." Philosophical Topics 47, no. 1 (2019): 1–20. http://dx.doi.org/10.5840/philtopics20194711.
Full textAbstract:
Neutral Theory is controversial in ecology. Ecologists and philosophers have diagnosed the source of the controversy as: its false assumption that individuals in different species within the same trophic level are ecologically equivalent, its conflict with Competition Theory and the adaptation of species, its role as a null hypothesis, and as a Lakatosian research programme. In this paper, I show why we should instead understand the conflict at the level of research programs which involve more than theory. The Neutralist and Competitionist research programs borrow and construct theories, models, and experiments for various aims and given their home ecological systems. I present a holistic and pragmatic view of the controversy that foregrounds the interrelation between many kinds of practices and decisions in ecological research.
27
Fabre, Virginie, Silvana Condemi, Anna Degioanni, and Estelle Herrscher. "Neanderthals versus Modern Humans: Evidence for Resource Competition from Isotopic Modelling." International Journal of Evolutionary Biology 2011 (September 15, 2011): 1–16. http://dx.doi.org/10.4061/2011/689315.
Full textAbstract:
During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.
28
Solé, Ricard V., Bernat Corominas-Murtra, and Jordi Fortuny. "Diversity, competition, extinction: the ecophysics of language change." Journal of The Royal Society Interface 7, no. 53 (June 30, 2010): 1647–64. http://dx.doi.org/10.1098/rsif.2010.0110.
Full textAbstract:
As indicated early by Charles Darwin, languages behave and change very much like living species. They display high diversity, differentiate in space and time, emerge and disappear. A large body of literature has explored the role of information exchanges and communicative constraints in groups of agents under selective scenarios. These models have been very helpful in providing a rationale on how complex forms of communication emerge under evolutionary pressures. However, other patterns of large-scale organization can be described using mathematical methods ignoring communicative traits. These approaches consider shorter time scales and have been developed by exploiting both theoretical ecology and statistical physics methods. The models are reviewed here and include extinction, invasion, origination, spatial organization, coexistence and diversity as key concepts and are very simple in their defining rules. Such simplicity is used in order to catch the most fundamental laws of organization and those universal ingredients responsible for qualitative traits. The similarities between observed and predicted patterns indicate that an ecological theory of language is emerging, supporting (on a quantitative basis) its ecological nature, although key differences are also present. Here, we critically review some recent advances and outline their implications and limitations as well as highlight problems for future research.
29
Biedma, Luis, Javier Calzada, José A. Godoy, and Jacinto Román. "Local habitat specialization as an evolutionary response to interspecific competition between two sympatric shrews." Journal of Mammalogy 101, no. 1 (December 28, 2019): 80–91. http://dx.doi.org/10.1093/jmammal/gyz203.
Full textAbstract:
Abstract Interspecific competition affects population dynamics, distributional ranges, and evolution of competing species. The competitive exclusion principle states that ecologically similar species cannot coexist unless they exhibit niche segregation. Herein, we assess whether niche segregation allows the coexistence of Crocidura russula and C. suaveolens in southwestern Iberia and whether segregation is the result of current (ecological effect) or past (evolutionary effect) competition. We performed an annual live-trapping cycle in the two main habitats of the Odiel Marshes Natural Reserve (OMNR), the tidal marsh and the Mediterranean forest, both in syntopic (i.e., where both species co-occur) and allotopic (where only one of the two species occurs) sites within this Reserve. We modeled the presence–absence of each species in both habitats and sites by generalized linear mixed models. The coexistence of both species was favored by spatial and temporal niche segregation. Crocidura suaveolens was restricted to tidal marsh and did not occupy Mediterranean forest, even when C. russula was absent. We interpret this to be the result of competition in the past triggering an evolutionary response in C. suaveolens towards its specialization in tidal marsh. Moreover, the specialist C. suaveolens currently is outcompeting C. russula in tidal marshes, reversing the dominance pattern observed elsewhere. The degree of co-occurrence between both species in syntopic sites was low, as they showed inverse dynamics of seasonal abundances. Interspecific competition leading to habitat specialization favors the coexistence of these ecologically similar species.
30
Fern, Rachel R., Michael L. Morrison, Hsiao-Hsuan Wang, William E. Grant, and Tyler A. Campbell. "Incorporating biotic relationships improves species distribution models: Modeling the temporal influence of competition in conspecific nesting birds." Ecological Modelling 408 (September 2019): 108743. http://dx.doi.org/10.1016/j.ecolmodel.2019.108743.
Full text
31
Germain, Rachel M., Margaret M. Mayfield, and Benjamin Gilbert. "The ‘filtering’ metaphor revisited: competition and environment jointly structure invasibility and coexistence." Biology Letters 14, no. 8 (August 2018): 20180460. http://dx.doi.org/10.1098/rsbl.2018.0460.
Full textAbstract:
‘Filtering’, or the reduction in species diversity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, controlled by the environment at large scales and competition at small scales. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test: (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on mechanisms underlying competitive coexistence. We find that competitors cause differential species persistence across environments even when effects are lacking in the absence of competition, and that the traits which determine persistence depend on the competitive environment. If our study had been observational and trait-based, we would have erroneously concluded that the environment filters species with low biomass, shallow roots and small seeds. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in the light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.
32
Pretzsch, Hans, and Peter Biber. "Size-symmetric versus size-asymmetric competition and growth partitioning among trees in forest stands along an ecological gradient in central Europe." Canadian Journal of Forest Research 40, no. 2 (February 2010): 370–84. http://dx.doi.org/10.1139/x09-195.
Full textAbstract:
Current individual tree growth models rarely consider the mode of tree competition, which can be size-asymmetric when growth is limited by light or size-symmetric when belowground resources are scarce. Even with the same competition index, growth reactions may vary considerably due to a prevailing resource limitation, as the dominant trees in a stand benefit disproportionately more on light-limited sites. To scrutinize and model the relationship between mode of competition and site conditions, 34 long-term experiments with 120 plots dating back to 1871 were used. The data cover the dominating tree species in central Europe along a broad range of ecological conditions. For Norway spruce ( Picea abies (L.) Karst.), Scots pine ( Pinus sylvestris L.), and sessile oak ( Quercus petrea (Matt.) Liebl.), stronger light competition can be shown on fertile sites compared with sites with poorer conditions. Based on these findings, we constructed an enhanced version of a classic potential modifier growth model. Simulations for archetypical stands yield a transition from size-asymmetric to size-symmetric competition along the gradient from fertile to poor sites that is not covered by traditional models. It was concluded that by integrating the interaction between competition and site quality, individual tree models become more site sensitive, a prerequisite for their application under fluctuating environmental conditions.
33
Clayton, Sophie, Stephanie Dutkiewicz, Oliver Jahn, Christopher Hill, Patrick Heimbach, and Michael J. Follows. "Biogeochemical versus ecological consequences of modeled ocean physics." Biogeosciences 14, no. 11 (June 16, 2017): 2877–89. http://dx.doi.org/10.5194/bg-14-2877-2017.
Full textAbstract:
Abstract. We present a systematic study of the differences generated by coupling the same ecological–biogeochemical model to a 1°, coarse-resolution, and 1∕6°, eddy-permitting, global ocean circulation model to (a) biogeochemistry (e.g., primary production) and (b) phytoplankton community structure. Surprisingly, we find that the modeled phytoplankton community is largely unchanged, with the same phenotypes dominating in both cases. Conversely, there are large regional and seasonal variations in primary production, phytoplankton and zooplankton biomass. In the subtropics, mixed layer depths (MLDs) are, on average, deeper in the eddy-permitting model, resulting in higher nutrient supply driving increases in primary production and phytoplankton biomass. In the higher latitudes, differences in winter mixed layer depths, the timing of the onset of the spring bloom and vertical nutrient supply result in lower primary production in the eddy-permitting model. Counterintuitively, this does not drive a decrease in phytoplankton biomass but results in lower zooplankton biomass. We explain these similarities and differences in the model using the framework of resource competition theory, and find that they are the consequence of changes in the regional and seasonal nutrient supply and light environment, mediated by differences in the modeled mixed layer depths. Although previous work has suggested that complex models may respond chaotically and unpredictably to changes in forcing, we find that our model responds in a predictable way to different ocean circulation forcing, despite its complexity. The use of frameworks, such as resource competition theory, provides a tractable way to explore the differences and similarities that occur. As this model has many similarities to other widely used biogeochemical models that also resolve multiple phytoplankton phenotypes, this study provides important insights into how the results of running these models under different physical conditions might be more easily understood.
34
Ferguson, Jake M., Mark L. Taper, Christopher S. Guy, and John M. Syslo. "Mechanisms of coexistence between native bull trout (Salvelinus confluentus) and non-native lake trout (Salvelinus namaycush): inferences from pattern-oriented modeling." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 4 (April 2012): 755–69. http://dx.doi.org/10.1139/f2011-177.
Full textAbstract:
Determining the ecological mechanisms that control population abundances is an important issue for the conservation of endangered and threatened species. We examined whether a threatened bull trout ( Salvelinus confluentus ) population could coexist at observed levels with the ecologically similar introduced species, lake trout ( Salvelinus namaycush ), using a pattern-oriented analysis of population dynamics models. We used a large suite of stage- and age-structured models to examine how both competitive and predatory interactions, combined with differing life-history strategies and species vital rates, drove salmonid coexistence patterns. In our models, an ontogenetic shift in juvenile bull trout resource use was the most important factor contributing to the two species coexistence; however, this coexistence occurred with reduced abundances in bull trout that increase the chances of extirpation for the native species. Observed levels of competition were found to have stronger effects than predation on population abundances. We used a pattern-oriented modeling approach to inference; this approach assumes process models that can generate patterns similar to the observed patterns are better supported than those that cannot. This methodology may find wide use on a number of data-limited fishery management and conservation problems.
35
Verhoeven, Michael R., Wesley J. Glisson, and Daniel J. Larkin. "Niche Models Differentiate Potential Impacts of Two Aquatic Invasive Plant Species on Native Macrophytes." Diversity 12, no. 4 (April 23, 2020): 162. http://dx.doi.org/10.3390/d12040162.
Full textAbstract:
Potamogeton crispus (curlyleaf pondweed) and Myriophyllum spicatum (Eurasian watermilfoil) are widely thought to competitively displace native macrophytes in North America. However, their perceived competitive superiority has not been comprehensively evaluated. Coexistence theory suggests that invader displacement of native species through competitive exclusion is most likely where high niche overlap results in competition for limiting resources. Thus, evaluation of niche similarity can serve as a starting point for predicting the likelihood of invaders having direct competitive impacts on resident species. Across two environmental gradients structuring macrophyte communities—water depth and light availability—both P. crispus and M. spicatum are thought to occupy broad niches. For a third dimension, phenology, the annual growth cycle of M. spicatum is typical of other species, whereas the winter-ephemeral phenology of P. crispus may impart greater niche differentiation and thus lower risk of native species being competitively excluded. Using an unprecedented dataset comprising 3404 plant surveys from Minnesota collected using a common protocol, we modeled niches of 34 species using a probabilistic niche framework. Across each niche dimension, P. crispus had lower overlap with native species than did M. spicatum; this was driven in particular by its distinct phenology. These results suggest that patterns of dominance seen in P. crispus and M. spicatum have likely arisen through different mechanisms, and that direct competition with native species is less likely for P. crispus than M. spicatum. This research highlights the utility of fine-scale, abundance-based niche models for predicting invader impacts.
36
Svanbäck, Richard, and Daniel I. Bolnick. "Intraspecific competition drives increased resource use diversity within a natural population." Proceedings of the Royal Society B: Biological Sciences 274, no. 1611 (December 19, 2006): 839–44. http://dx.doi.org/10.1098/rspb.2006.0198.
Full textAbstract:
Resource competition is thought to play a major role in driving evolutionary diversification. For instance, in ecological character displacement, coexisting species evolve to use different resources, reducing the effects of interspecific competition. It is thought that a similar diversifying effect might occur in response to competition among members of a single species. Individuals may mitigate the effects of intraspecific competition by switching to use alternative resources not used by conspecific competitors. This diversification is the driving force in some models of sympatric speciation, but has not been demonstrated in natural populations. Here, we present experimental evidence confirming that competition drives ecological diversification within natural populations. We manipulated population density of three-spine sticklebacks ( Gasterosteus aculeatus ) in enclosures in a natural lake. Increased population density led to reduced prey availability, causing individuals to add alternative prey types to their diet. Since phenotypically different individuals added different alternative prey, diet variation among individuals increased relative to low-density control enclosures. Competition also increased the diet–morphology correlations, so that the frequency-dependent interactions were stronger in high competition. These results not only confirm that resource competition promotes niche variation within populations, but also show that this increased diversity can arise via behavioural plasticity alone, without the evolutionary changes commonly assumed by theory.
37
Silva, IA, and MA Batalha. "Phylogenetic overdispersion of plant species in southern Brazilian savannas." Brazilian Journal of Biology 69, no. 3 (August 2009): 843–49. http://dx.doi.org/10.1590/s1519-69842009000400011.
Full textAbstract:
Ecological communities are the result of not only present ecological processes, such as competition among species and environmental filtering, but also past and continuing evolutionary processes. Based on these assumptions, we may infer mechanisms of contemporary coexistence from the phylogenetic relationships of the species in a community. We studied the phylogenetic structure of plant communities in four cerrado sites, in southeastern Brazil. We calculated two raw phylogenetic distances among the species sampled. We estimated the phylogenetic structure by comparing the observed phylogenetic distances to the distribution of phylogenetic distances in null communities. We obtained null communities by randomizing the phylogenetic relationships of the regional pool of species. We found a phylogenetic overdispersion of the cerrado species. Phylogenetic overdispersion has several explanations, depending on the phylogenetic history of traits and contemporary ecological interactions. However, based on coexistence models between grasses and trees, density-dependent ecological forces, and the evolutionary history of the cerrado flora, we argue that the phylogenetic overdispersion of cerrado species is predominantly due to competitive interactions, herbivores and pathogen attacks, and ecological speciation. Future studies will need to include information on the phylogenetic history of plant traits.
38
Feyerlein, Daniel. "Intensify Business Performances of Multinationals: An Introduction to Five Strategic Elements within Performance Management." International Journal of Business and Management 12, no. 5 (April 27, 2017): 17. http://dx.doi.org/10.5539/ijbm.v12n5p17.
Full textAbstract:
The unknown future of global change, the increasing influence of growing and altered market conditions – these critical issues require companies around the globe that operate internationally to progressively adapt and optimize their strategies. In particular, regarding future competition conditions, strengthening competitiveness is gaining more importance. Companies are being challenged to define their business models and strategies in accordance with global requirements in order to compete successfully.Particularly in times of inconsistency, suggestions for performance improvement can provide valuable impulses. This article highlights current aspects within international business and considers future market conditions with a focus on strategic management and raising competitiveness.Performance management, the core element of business models, suggests five strategic elements that show promising potential for improving the performance of multinationals: beneficial proposals, commercial excellence, leadership aspiration, gaining competitiveness and ecological sustainability. With a focus on strategizing, performance management aims at generating continuous improvement of the organization’s competitive situation internationally while factoring in global change. This article focuses on manufacturing companies that pursue long term growth targets in international business and that has to deal with permanently growing competition at an international level.
39
Hülsmann, Lisa, Harald Bugmann, and Peter Brang. "How to predict tree death from inventory data — lessons from a systematic assessment of European tree mortality models." Canadian Journal of Forest Research 47, no. 7 (July 2017): 890–900. http://dx.doi.org/10.1139/cjfr-2016-0224.
Full textAbstract:
The future development of forest ecosystems depends critically on tree mortality. However, the suitability of empirical mortality algorithms for extrapolation in space or time remains untested. We systematically analyzed the performance of 46 inventory-based mortality models available from the literature using nearly 80 000 independent records from 54 strict forest reserves in Germany and Switzerland covering 11 species. Mortality rates were predicted with higher accuracy if covariates for tree growth and (or) competition at the individual level were included and if models were applied within the same ecological zone. In contrast, classification of dead vs. living trees was only improved by growth variables. Management intensity in the calibration stands, as well as the census interval and size of the calibration datasets, did not influence model performance. Consequently, future approaches should make use of tree growth and competition at the level of individual trees. Mortality algorithms for applications over a restricted spatial extent and under current climate should be calibrated based on datasets from the same region, even if they are small. To obtain models with wide applicability and enhanced climatic sensitivity, the spatial variability of mortality should be addressed explicitly by considering environmental influences using data of high temporal resolution covering large ecological gradients. Finally, such models need to be validated and documented thoroughly.
40
Wilson, Alan G. "Ecological and Urban Systems Models: Some Explorations of Similarities in the Context of Complexity Theory." Environment and Planning A: Economy and Space 38, no. 4 (April 2006): 633–46. http://dx.doi.org/10.1068/a37102.
Full textAbstract:
There are similarities of form between urban system models and models of ecosystems. These are systematically explored and a general model formulation which embraces both kinds of model is presented. Some insights are gained by using ideas from ecosystem modelling in urban modelling. The biggest gains, however, are for ecosystem modelling. It is demonstrated that urban techniques can be used for incorporating spatial competition effects into such models in novel ways, and that the complex dynamics can then be effectively interpreted. Urban systems have contributed significantly to complexity theory in the past—because they are complicated enough to be interesting but simple enough to be solvable. These insights can now be transferred to complex (spatial) ecosystems. The possibility of joint eco-urban models is explored.
41
González Barrios, Pablo, Alejandra Borges, José Terra, Mario Pérez Bidegain, and Lucía Gutiérrez. "Spatio-Temporal Modeling and Competition Dynamics in Forest Tillage Experiments on Early Growth of Eucalyptus grandis L." Forest Science 66, no. 5 (March 28, 2020): 526–36. http://dx.doi.org/10.1093/forsci/fxaa007.
Full textAbstract:
Abstract Forest tillage experiments regularly use long-term evaluations of large plots creating temporal and/or spatial correlations among observations. Not modeling these correlations could compromise treatment comparisons. The aim of this study was to evaluate the effect of modeling spatio-temporal (ST) variability in forest tillage experiments. We used different strategies that incorporate spatial and/or temporal correlations in the evaluation of tillage intensity effect in initial Eucalyptus growth as well as evaluate the effect of intraplot mortality and competition dynamics. Three tillage intensities in two contrasting soil conditions were compared for tree height and wood volume. Additionally, we compared the use of three individual growth curves for plant height to evaluate the time needed to reach 2 m in height (T2m). We modeled the spatial correlation of T2m using mixed models. In both sites, ST models were superior for plant height and wood volume per hectare, whereas for individual-tree wood volume, temporal models were superior. Pit planting always had a lower performance than disk harrowing and subsoiler, which behaved similarly. The competition dynamics within the plot because of tree mortality was affected by treatments and site. Modeling ST variability is key to improving treatment comparisons in forest experiments.
42
Izhar, Rony, Jarkko Routtu, and Frida Ben-Ami. "Host age modulates within-host parasite competition." Biology Letters 11, no. 5 (May 2015): 20150131. http://dx.doi.org/10.1098/rsbl.2015.0131.
Full textAbstract:
In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa , we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters.
43
Izar, Patrícia. "Female Social Relationships of Cebus apella nigritus in a Southeastern Atlantic Forest: An Analysis Through Ecological Models of Primate Social Evolution." Behaviour 141, no. 1 (2004): 71–99. http://dx.doi.org/10.1163/156853904772746619.
Full textAbstract:
AbstractTheoretical models about female relationships within primate social groups hypothesise that food abundance and distribution are important factors determining the variation of patterns observed among species and populations. Despite some common premises, models formulated by van Schaik (1989) and Sterck et al. (1997) and by Isbell (1991) differ with respect to the importance of predation risk, the co-variation of contest and scramble competition and causes of female dispersal. In this study, data from a population of Cebus apella nigritus from Brazilian Atlantic Forest are analysed using predictions from these models. Competition among females, both within and between groups, is strong and related to food abundance and distribution. Females can transfer between groups, as well as males. Female dispersal is related to a significant reduction in per capita energy intake by group foragers during fruit scarcity periods. The data from this study are not conclusive about the importance of predation in causing variation of female relationships but favour the assumption from van Schaik and Sterck et al. that contest and scramble competition within and between groups can vary independently; and also favour the formulation from Isbell & Van Vuren (1996) on female dispersal. The exact pattern of female social relationships is not sufficiently explained by ecological causes alone. Social benefits provided by the dominant male also seem to be important.
44
Zhang, Zizhen, Ranjit Kumar Upadhyay, Rashmi Agrawal, and Jyotiska Datta. "The Gestation Delay: A Factor Causing Complex Dynamics in Gause-Type Competition Models." Complexity 2018 (November 7, 2018): 1–21. http://dx.doi.org/10.1155/2018/1589310.
Full textAbstract:
In this paper, we consider a Gause-type model system consisting of two prey and one predator. Gestation period is considered as the time delay for the conversion of both the prey and predator. Bobcats and their primary prey rabbits and squirrels, found in North America and southern Canada, are taken as an example of an ecological system. It has been observed that there are stability switches and the system becomes unstable due to the effect of time delay. Positive invariance, boundedness, and local stability analysis are studied for the model system. Conditions under which both delayed and nondelayed model systems remain globally stable are found. Criteria which guarantee the persistence of the delayed model system are derived. Conditions for the existence of Hopf bifurcation at the nonzero equilibrium point of the delayed model system are also obtained. Formulae for the direction, stability, and period of the bifurcating solution are conducted using the normal form theory and center manifold theorem. Numerical simulations have been shown to analyze the effect of each of the parameters considered in the formation of the model system on the dynamic behavior of the system. The findings are interesting from the application point of view.
45
Montana, Luca, François Rousseu, Dany Garant, and Marco Festa-Bianchet. "Siring success in kangaroos: size matters for those in the right place at the right time." Behavioral Ecology 31, no. 3 (March 19, 2020): 750–60. http://dx.doi.org/10.1093/beheco/araa020.
Full textAbstract:
Abstract In polygynous species, male reproductive success is predicted to be monopolized by a few dominant males. This prediction is often not supported, suggesting that ecological and alternative mating tactics influence siring success. The spatiotemporal distribution of individuals and the number of males competing for each receptive female are often overlooked because they are difficult to monitor in wild animals. We examined how spatial overlap of female–male pairs, the time spent by a male on the breeding site, number of competitors, and morphological traits influence siring probability in eastern gray kangaroos (Macropus giganteus). We compared home range overlap for 12 208 dam–male pairs and 295 known dam–sire pairs to define local competitive groups and to estimate every male’s opportunity to sire the young of each female. We compared models considering morphological traits relative to the entire population or to local competitive groups. Including local competition improved model performance because it estimated the intensity of competition and compared each male’s morphological traits to those of its competitive group. Regardless of size, males can increase their probability to sire a young by increasing their mating opportunity relative to the mother. We underline the importance of considering spatial structure to assess the intensity of competition in species where males cannot equally access all females in a population. The estimation of mating opportunity and intensity of local competition improves our understanding of how morphological traits affect siring success when each mating event involves a different set of competing males, a characteristic of most wild species.
46
Cohen, Dan. "Conceptual models of the processes and patterns of the ecological, evolutionary and bio-geographical consequences of global climate changes." Israel Journal of Ecology and Evolution 59, no. 4 (May 6, 2013): 201–13. http://dx.doi.org/10.1080/15659801.2013.929276.
Full textAbstract:
A unifying conceptual model is constructed for the major effects of alternating periods of global warming and cooling and sea-level changes on the geographical distributions and the ecological and genetic characteristics of species and ecological communities. The main results found are: The species in the interior of continuous global latitude and altitude temperature gradients are expected to follow the moving temperature zones without any major extinctions or any major changes in their physiological and ecological characteristics and adaptive roles during both global warming and global cooling periods, with competitive replacement of resident species by zonally dispersing pre-adapted species. Many or all of the existing species at all the global cold boundary zones of both latitude and altitude temperature gradients are expected to become extinct during periods of global warming, which would be caused by competitive displacement by immigrating pre-adapted species from adjacent warmer zones. Most existing species in the warm boundary zones of all the global temperature gradients are predicted to persist and adapt without competition to the increased temperature during periods of global warming, and to diversify by adaptations to newly created ecological opportunities. Periods of global cooling are predicted to cause analogous opposite effects to the effects of global warming in the cold and warm boundaries of temperature gradients: that is, extinctions at the warm boundaries and persistence and adaptations at the cold boundaries: Existing species in all islands and island-like isolated areas are predicted to persist in the absence of competitive displacement by immigrating pre-adapted species, and gradually adapt to the changing temperatures during periods of both global warming and global cooling. During periods of global cooling, many more diverse opportunities for new adaptations and for invasions by pre-adapted species are expected and predicted in the large diversity of the newly open heterogeneous coldest and highest altitude zones of all the global altitude temperature gradients. Long-term sequences of alternating periods of global warming and global cooling are expected to cancel and eliminate most of the ecological and adaptive changes which have occurred during the previous periods at all the latitude and altitude boundary zones. The species at the interior of continuous temperature gradients are expected to persist unchanged over long evolutionary time during repeated sequences of alternating periods of global warming and global cooling. The effects of higher and lower global sea levels on the sea shore and intertidal species and communities during periods of global warming or cooling are expected to be analogous to the bio-geographical, ecological and genetic changes caused or predicted by global warming or cooling in the species and communities in terrestrial or marine temperature gradients. Global sea-level changes which cause higher or lower shifting of the levels of the ecological zones in continuous sea shore gradients are expected therefore to cause continuous tracking and moving of the populations of the unchanged zonally adapted species. On the other hand, zonally adapted sea shore species are expected to be displaced or become extinct during periods of sea-level changes at the higher or lower boundary zones of the sea-level gradients in semi-isolated marine basins, and in locally discontinuous, fragmented or truncated sea shore ecological gradients.
47
González-Olivares, Eduardo, Javier Cabrera-Villegas, Fernando Córdova-Lepe, and Alejandro Rojas-Palma. "Competition among Predators and Allee Effect on Prey, Their Influence on a Gause-Type Predation Model." Mathematical Problems in Engineering 2019 (March 21, 2019): 1–19. http://dx.doi.org/10.1155/2019/3967408.
Full textAbstract:
Interference or competition among predators (CAP) has often been ruled out in depredation models, although there are varied mathematical forms to describe and incorporate it into this interaction. In this work, we present the most known of these descriptions and one of them will be used in a modified Volterra model. Moreover, of this ecological phenomenon, a simple and strong Allee effect affecting the prey population will be considered in the relationship. An important feature of the new model is to have until two positive equilibrium points, to the difference with the Volterra model (without Allee effect); hence different and interesting dynamic situations appear in the system. Conditions for the existence and local stability of equilibria are determined. The boundedness of solutions, the existence of a limit cycle and a separatrix curve are also proven. Besides, the main properties of the model are examined from an ecological point of view. To make a comparative discussion of our results, an Appendix is added with the main properties of models, in which neither the Allee effect nor the competition among predators is considered. Some simulations are shown to endorse our results.
48
Griswold, Cortland K. "Epistasis can accelerate adaptive diversification in haploid asexual populations." Proceedings of the Royal Society B: Biological Sciences 282, no. 1802 (March 7, 2015): 20142648. http://dx.doi.org/10.1098/rspb.2014.2648.
Full textAbstract:
A fundamental goal of the biological sciences is to determine processes that facilitate the evolution of diversity. These processes can be separated into ecological, physiological, developmental and genetic. An ecological process that facilitates diversification is frequency-dependent selection caused by competition. Models of frequency-dependent adaptive diversification have generally assumed a genetic basis of phenotype that is non-epistatic. Here, we present a model that indicates diversification is accelerated by an epistatic basis of phenotype in combination with a competition model that invokes frequency-dependent selection. Our model makes use of a genealogical model of epistasis and insights into the effects of balancing selection on the genealogical structure of a population to understand how epistasis can facilitate diversification. The finding that epistasis facilitates diversification may be informative with respect to empirical results that indicate an epistatic basis of phenotype in experimental bacterial populations that experienced adaptive diversification.
49
Simões, Marianna V. P., and A. Townsend Peterson. "Importance of biotic predictors in estimation of potential invasive areas: the example of the tortoise beetleEurypedus nigrosignatus, in Hispaniola." PeerJ 6 (December 5, 2018): e6052. http://dx.doi.org/10.7717/peerj.6052.
Full textAbstract:
Climatic variables have been the main predictors employed in ecological niche modeling and species distribution modeling, although biotic interactions are known to affect species’ spatial distributions via mechanisms such as predation, competition, and mutualism. Biotic interactions can affect species’ responses to abiotic environmental changes differently along environmental gradients, and abiotic environmental changes can likewise influence the nature of biotic interactions. Understanding whether and how to integrate variables at different scales in ecological niche models is essential to better estimate spatial distributions of species on macroecological scales and their responses to change. We report the leaf beetleEurypedus nigrosignatusas an alien species in the Dominican Republic and investigate whether biotic factors played a meaningful role in the distributional expansion of the species into the Caribbean. We evaluate ecological niche models built with an additive gradient of unlinked biotic predictors—host plants, using likelihood-based model evaluation criteria (Akaike information criterion and Bayesian information criterion) within a range of regularization multiplier parameter values. Our results support the argument that ecological niche models should be more inclusive, as selected biotic predictors can improve the performance of models, despite the increased model complexity, and show that biotic interactions matter at macroecological scales. Moreover, we provide an alternative approach to select optimal combination of relevant variables, to improve estimation of potential invasive areas using global minimum model likelihood scores.
50
De los Ríos Escalante, Patricio. "Null models for understanding fairy shrimp habitats." Animal Biology 67, no. 3-4 (2017): 331–38. http://dx.doi.org/10.1163/15707563-00002532.
Full textAbstract:
The Chilean fairy shrimp species are represented by the Branchinecta genus, which are poorly described, and mainly occur in shallow ephemeral pools in the Atacama Desert of northern Chile and the Southern Chilean Patagonian plains. The aim of the present study was to perform an initial ecological characterization of Branchinecta habitats and its associated communities in the Chilean Southern Patagonian plains (45-53°S) using null models (co-occurrence, niche sharing and size overlap). The results of the co-occurrence analysis revealed that the species’ associations are structured, meaning that at different kinds of Branchinecta habitats, the associated species are different. I did not find niche sharing, which means interspecific competition is absent. Finally the size overlap analysis revealed structured patterns, which are probably due to environmental homogeneity or colonization extinction processes. The habitats studied are shallow ephemeral pools, with extreme environmental conditions, where continuous local colonization and extinction processes probably occur, which would explain the marked Branchinecta species endemism.