Dissertations / Theses on the topic 'Interspecific variation'

Plants emit a diverse range of biogenic volatile organic compounds (BVOCs) into the atmosphere, of which isoprene is the most abundantly emitted. Isoprene significantly affects biological and atmospheric processes, but the range of isoprene and BVOCs present in bamboos has not been well characterized. In this thesis I explore the range of isoprene emission found in bamboos and relate it to plant morphological and physiological characteristics. In addition, I measure and relate the entire suite of BVOCs present in the bamboos to their fundamental isoprene emission rate. Interspecific variation in isoprene emission documented in a comprehensive survey of bamboos. Two groups of bamboo species were measured in the greenhouse and the field. Elevated photosynthetic rate was significantly correlated with isoprene emission. In the field, dark respiration rate was highest in bamboos that made the least amount of isoprene. The total BVOC suite was significantly influenced by whether or not leaf-level isoprene emission was present. I conclude that bamboos vary with regard to physiology, morphology, and total BVOC suite and that isoprene emission is correlated with these changes, and introduce the bamboos as a novel system for studying the impacts of isoprene emission.

Biological invasions continue to alter the structure and functioning of ecosystems worldwide. While the vectors and pathways of establishment of Invasive species are understood, predicting the ecological changes, or impacts, these species can exert on recipient ecosystems is lacking. Using invasive freshwater amphipods as models, this thesis aimed to investigate the role of intraspecific variation and interspecific interactions in understanding and predicting invasive species' impacts. This work first looks at the inherent variation in feeding behaviour within and between populations of an invasive amphipod, and discusses the implications of such variation for the use of functional responses, or the relationship between feeding rate and prey density. in invasion ecology. Secondly, behaviours associated to dispersal and impacts, as well as parasitic profiles, are compared between two UK populations of Dikerogammarus villosus. Differences between the populations show that monitoring population level differences, including behaviour and parasitism, can inform on invasive species' spread and impacts. Thirdly, interspecific interactions are used in order to elucidate the potential impac s of Dikerogammarus haemobaphes. Two aspects in particular are highlighted: predator-prey interactions, using the comparative functional response framework, and interference competition with D. villosus in terms of habitat use. Finally. cross-ecosystem interspecilic interactions are considered and their effects on a critical ecological process: leaf litter degradation. Using two invasive/native plant pairings, the individual leaf shredding abilities of an invasive and a native amphipod are compared in a laboratory setting. While both native plant species were consumed more readily, no difference was detected between the two amphipods. However, an in situ leaf litter bag experiment showed that the indirect effect of the invasive amphipod on macroinvertebrate community diversity may modify the degradation of certain plant species. This thesis therefore provides empirical evidence of the importance of intraspecific variation and interspecific interactions for the furthering predictive ecology

Dental morphology and tooth shape have been used to recreate the dietary adaptations for extinct species, and thus dental variation can provide information on the relationship between fossil species and their paleoenvironments. Variation in living species with known behaviors can provide a baseline for interpreting morphology, and behavior, in the fossil record. Tooth occlusal surface outlines in hominins and non-hominin primates, and other mammals, have been used for assessments of taxonomic significance, with variability often considered as being primarily phylogenetic. Few studies have attempted to assess how diet might influence the pattern of variability in closely related species. Here the occlusal surface shape variability in anterior and postcanine maxillary dentition in primates is measured to assess whether the relationship between diet and variability is consistent. Data were collected from five non-hominin primates in a range of dietary categories, as well as two hominin species, including the derived Paranthropus robustus and a gracile australopith. Mapping a series of 50 sliding semilandmarks based on 2-D photographs using tpsDig software, occlusal surfaces were outlined. Thereafter, outline shapes were quantified using Elliptical Fourier Functional Analysis, and principle components and multivariate analyses were preformed to explore the pattern of intra and interspecific variability in occlusal outlines.These results suggest that there is not a clear relationship between dietary feeding adaptations for all categories examined and selection for larger premolars and molars, as well as smaller incisors, led to less variation in both anterior and post-canine teeth of the fossil hominin Paranthropus robustus.

The aim of this project was to study the population genetics of Echinostoma trivolvis, a parasitic trematode that uses multiple hosts in its lifecycle and has a significant impact on amphibian populations. Microsatellite markers were to be identified and isolated because of their highly variable nature and reported ease of use with PCR. Parasite DNA was extracted from planorbid snails from several locations within California including: Point Reyes National Seashore, Lake Tahoe, and the San Francisco Bay Area. In addition, parasite samples were obtained from Manitoba, Canada. Several microsatellites were identified and 29 PCR primers sets were designed, six of which were capable of amplifying consistently. Sequencing other published molecular markers, COl, NDl, and ITS, unveiled intriguing phylogenetic relationships and potential cryptic species. The echinostome population in central California, as a result of this project, may be much more diverse than has long been reported in the literature.

Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter- and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330-m elevation gradient in Peru, and in sun leaves across a forest-savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T-statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community- weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche-based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored.

Os parques eólicos estão associados a impactos em diferentes grupos de animais e as aves planadoras são um dos mais afetados. Neste estudo avaliamos diferenças interespecíficas no comportamento de evitamento de aves planadoras migradoras ao cruzarem um parque eólico no Sudoeste de Portugal. Analisámos alterações de distância às turbinas e na sinuosidade dos movimentos, comparando entre períodos antes e após a construção do parque eólico. Para além de diferenças entre espécies examinámos também diferenças no uso de diferentes classes de altura. Os resultados revelam que, após a construção, (1) os movimentos das aves são mais sinuosos, (2) algumas espécies privilegiam voos acima das turbinas, (3) bandos de águias-calçadas voam a maiores distâncias do parque e (4) os abutres não demonstram evitamento. Este estudo evidencia respostas de evitamento das turbinas por parte das aves, os quais podem resultar em gastos energéticos adicionais que poderão afetar o sucesso da migração. Isto pode servir de base para a definição de medidas de mitigação em parques eólicos diferenciadas ao nível da espécie; Abstract: Wind farms are associated with impacts on different animal groups and soaring birds are one of the most affected. In this study, we assess interspecific differences in avoidance behaviours of migratory soaring bird species while crossing a windfarm in southwestern Portugal. We analysed changes in movements’ distance to turbines and linearity, comparing between periods before and after the windfarm implementation. Beside differences between species, we also examined differences in the use of height classes. The results reveal that after the construction of the wind farm (1) birds’ movements are more sinuous, (2) some species favour flights above the turbines, (3) flocks of Booted Eagles fly at greater distances from turbines and (4) vultures show no avoidance responses. Our study highlights the existence of bird avoidance responses to wind turbines, which may result in additional energy demands that might affect the migration success. This may be used as a base to define mitigation measures in windfarms at a species level.

Les xarxes complexes serveixen als ec olegs per a estudiar les interaccions de pollinitzaci o a nivell comunitari. Actualment, es necessari construir xarxes que siguin representacions m es realistes del proc es de pol.linitzaci o per tal d'incrementar la seva utilitat pr actica. Per aix o, aquesta tesi es centra en incorporar a les xarxes la variaci o interindividual i informaci o sobre la magnitud i el signe (positiu, neutre o negatiu) dels efectes de les interaccions sobre la reproducci o de les plantes. Les esp ecies consten de poblacions d'individus amb fenotips, genotips i comportaments diferents, que per tant poden diferir en les interaccions. Aquesta variaci o intraespec ca es rellevant per molts processos ecol ogics i evolutius, per o no s'ha tengut en compte en la majoria d'estudis de xarxes planta-pol.linitzador. En els cap tols 1 i 2 s'estudien les c arregues pol.l niques d'exemplars d'insectes pol.linitzadors en dues comunitats de muntanya a Mallorca i es construeixen xarxes on els nodes dels pol.linitzadors representen individus en lloc d'esp ecies. Aquesta aproximaci o permet considerar la variaci o interindividual i aporta una nova perspectiva sobre l'estructura de les xarxes i els mecanismes que determinen les interaccions. Les xarxes de transport de pol.len a nivell d'individu tenen una densitat d'interaccions, connect ancia, grau d'anidament i diversitat d'interaccions m es baixa que les mateixes xarxes a nivell d'esp ecies, i per contra una modularitat major. Es troben aquestes difer encies perqu e les esp ecies de pol.linitzadors generalistes estan formades per individus especialistes i heterogenis en l' us de recursos. El grau d'especialitzaci o individual est a associat a la intensitat de compet encia inter- i intraespec ca. Per a que les xarxes planta-pol.linitzador representin millor les implicacions funcionals, han d'incloure mesures dels efectes de les interaccions sobre les esp ecies o de la magnitud real en qu e les esp ecies depenen d'aquestes interaccions. La freq u encia d'interacci o es considera una estimaci o v alida de la magnitud de l'efecte del pol.linitzador sobre l' exit reproductiu de la planta, per o no aporta cap informaci o del seu signe. Per exemple, en plantes amb mecanismes de producci o de llavors que no depenen d'insectes (e.g. autog amia, anemog amia), les interaccions poden tenir efectes neutres sobre la reproducci o. En el cap tol 3, per diferents plantes de dues comunitats d'estudi (costa i muntanya) es quanti ca el seu grau de depend encia dels pol.linitzadors, comparant experimentalment la producci o de llavors amb i sense insectes. L'objectiu es determinar si les esp ecies que s on m es depenents dels pol.linitzadors s on tamb e les que estan m es connectades en les xarxes de visites orals, es a dir si tenen major centralitat, nombre i diversitat d'interaccions. Nom es en una de les dues comunitats estudiades es troba aquesta relaci o, fet que suggereix que pot dependre del contexte comunitari. D'altra banda, hi ha interaccions que poden causar m es efectes negatius que positius sobre l' exit reproductiu de les plantes. Aix o pot passar quan els pol.linitzadors depositen pol.len conespec c en els estigmes, per o alhora tamb e pol.len heterospec c. La transfer encia interespec ca de pol.len es relativament comuna, perqu e sovint les esp ecies de oraci o simult ania comparteixen pol.linitzadors, i pot tenir efectes perjudicials per les plantes (e.g. p erdua de pol.len, obstrucci o dels estigmes). En el cap tol 4, s'estudien les transfer encies de pol.len interespec ques en tres comunitats andines al llarg d'un gradient altitudinal. Es construeixen xarxes dirigides representant la transfer encia de pol.len des de les esp ecies donants a les receptores i a cada interacci o de la xarxa s'hi associa un signe per representar l'efecte. Aquest signe s'obt e de la relaci o entre el pol.len conespec c i heteroespec c depositat sobre els estigmes. En totes les comunitats estudiades, les interaccions positives i neutres s on predominants, particularment en la comunitat de major altitud. Aquesta troballa suggereix que la facilitaci o entre plantes d'una comunitat pot augmentar quan les condicions pel servei de pol.linitzaci o es tornen menys favorables.
Las redes complejas sirven a los ec ologos para estudiar las interacciones de polinizaci on a nivel comunitario. Actualmente, para incrementar su utilidad pr actica, es necesario construir redes que sean representaciones lo m as realistas posibles del proceso de polinizaci on. Por este motivo, esta tesis se centra en incorporar a las redes la variaci on interindividual y informaci on sobre la magnitud y el signo (positivo, neutro o negativo) de los efectos de las interacciones sobre la reproducci on de las plantas. Las especies constan de poblaciones de individuos con fenotipos, genotipos y comportamientos distintos, que por tanto pueden diferir en sus interacciones. Esta variaci on intraespec ca es relevante para muchos procesos ecol ogicos y evolutivos, pero no se ha considerado en la mayor a de estudios de redes plantapolinizador. En los cap tulos 1 y 2 se estudian las cargas pol nicas de ejemplares de insectos polinizadores en dos comunidades de monta~na en Mallorca y se construyen redes donde los nodos de los polinizadores representan individuos en lugar de especies. Esto permite incorporar la variaci on interindividual y aportar una nueva perspectiva sobre la estructura de las redes y los mecanismos que determinan las interacciones. Las redes de transporte de polen a nivel de individuo tienen una densidad de interacciones, conectancia, anidamiento y diversidad de interacciones m as baja que las mismas redes a nivel de especies, pero una modularidad mayor. Estas diferencias ocurren porque las especies de polinizadores generalistas est an formadas por individuos especialistas y heterog eneos en la utilizaci on de recursos. El grado de especializaci on individual est a asociado a la intensidad de competencia inter- e intraespec ca. Para que las redes planta-polinizador sean m as representativas de las implicaciones funcionales deben incluir medidas de los efectos de las interacciones sobre las especies o de la magnitud real en que las especies dependen de estas interacciones. La frecuencia de interacci on se considera una estimaci on v alida del efecto del polinizador sobre el exito reproductivo de la planta, aunque no aporta informaci on sobre su signo. Por ejemplo, en plantas con mecanismos de producci on de semillas independientes de los insectos (e.g. autogamia, anemogamia), las interacciones pueden tener efectos neutros sobre la reproducci on. En el cap tulo 3, para diferentes plantas de dos comunidades de estudio (costa y monta~na) se cuanti ca el grado de dependencia de polinizadores comparando experimentalmente la producci on de semillas con y sin insectos. El objetivo es determinar si las especies m as dependientes de polinizadores son tambi en las m as conectadas en las redes, con mayor centralidad, n umero y diversidad de interacciones. S olo en una de las comunidades de estudio se encuentra esta relaci on, sugiriendo que es variable en funci on del contexto comunitario. Por otro lado, hay interacciones que pueden causar efectos m as negativos que positivos sobre el exito reproductivo de las plantas. Esto puede pasar cuando los polinizadores depositan polen conespec co y heterospec co en los estigmas. La transferencia interespec ca de polen es relativamente com un, porque a menudo las especies de oraci on simult anea comparten polinizadores, y puede tener efectos perjudiciales para las plantas (e.g. p erdida de polen, obstrucci on de estigmas). En el cap tulo 4, se estudian las transferencias de polen interespec cas en tres comunidades andinas a lo largo de un gradiente altitudinal. Se construyen redes dirigidas que representan la transferencia de polen desde las especies donantes a las receptoras y a cada interacci on se le asocia un signo mostrando el efecto. Este signo se obtiene de la relaci on entre el polen conespec co y heteroespec co depositado sobre los estigmas. En todas las comunidades estudiadas, predominan las interacciones positivas y neutras, particularmente en la comunidad de mayor altitud. Esto sugiere que la facilitaci on en una comunidad puede aumentar cuando las condiciones para la polinizaci on se vuelven menos favorables.
Ecologists use network analysis to study pollination interactions at a communitywide level. The construction of plant-pollinator networks which are realistic representations of the pollination process is fundamental to increase their usefulness and ecological meaning. For that reason, this thesis focuses on incorporating to such networks individual variation and information about the magnitude and sign (positive, neutral or negative) of interaction e ects on plant reproduction. Species consist of populations of phenotypically, genetically and behaviourally diverse individuals which thus di er in their interactions and foraging decisions. Despite its relevance for many ecological and evolutionary processes, intraspeci c variation has been overlooked in most plant-pollinator network studies. In chapters 1 and 2, pollen loads of insect pollinator individuals are studied in two mountain communities of Mallorca, and networks where pollinator nodes depict individuals instead of species are built. Such approach (network downscaling) permits to account for the variation within species and provides new insights on network interaction patterns and their causal mechanisms. Pollen-transport networks at the individual level had lower linkage density, connectance, nestedness and interaction diversity, than the same networks at the species level, but higher modularity. These di erences occur because generalist pollinator species are composed of heterogeneous specialist individuals in the use of resources. The degree of individual specialization is associated with inter- and intraspeci c competition. Plant-pollinator networks which represent more accurately functional implications should include measures of interaction e ects on species or estimates of the actual degree to which species depend on such interactions. In general, interaction frequency is considered a good surrogate of the magnitude of interaction e ects, although it does not give any information about the e ect sign. For instance, in plant species with mechanisms for producing seeds independently of pollinators (e.g. autogamy, anemogamy), interactions may have a neutral reproductive e ect. In chapter 3, the degree of reproductive dependence on pollinators is quanti ed for several plant species in two study communities (coast and mountain), comparing seed set with and without insects. The objective is to determine whether plant species which depend more on pollinators are also more connected in ower-visitation networks, i.e. have high centrality, number and diversity of interactions. Such relationship is only found in one of the two study communities, which suggests that it is community-context dependent. On the other hand, there are interactions which may cause more negative than positive e ects on plant reproductive success. This may happen when owervisitors deposit both conspeci c and heterospeci c pollen on stigmas. Such interspeci c pollen transfer is common because co- owering plants often share pollinators, and can have detrimental e ects on plant tness (e.g. pollen loss and stigma clogging). In chapter 4, interspeci c pollen transfers are studied in three high-Andean communities along a mountain altitudinal gradient. Directed networks depicting pollen transfers from donor to receptor species are constructed, and a sign is associated to each network link to represent the e ect. This sign is obtained from the study of the relationship between conspeci c and heterospeci c pollen deposited on stigmas. In all study communities, facilitative and neutral pollinator-mediated interactions among plants prevail over competition, particularly in the highest elevation community. This nding suggests that pollination facilitation in communities can increase under less favourable conditions for the pollination service, supporting previous predictions of higher incidence of facilitative interactions in stressful environments.

Intertidal populations of the sea urchin Parechinus angulosus were examined at seven sites along the south and east coasts of South Africa. At the five southerly sites, P. angulosus occurred in allopatry, while, at the two northerly sites, it occurred in sympatry with several species of Indopacific sea urchins. At the five southerly sites, there was a significant correlation of number of sea urchins per pool with the surface area of the overhang in that pool. This relationship broke down for P. angulosus at the two northerly sites, where there was a significant correlation between these two factors for Stomopneustes variolaris. The density of populations of P. angulosus at the two northerly sites, although not significantly different from all five southerly sites, were considerably lower. There was a significant difference between the mean size of populations at the seven sites. Although no direct evidence is available, a competitive interaction between these two species is proposed to explain the observed patterns of microhabitat utilization and densities. Two series of manipulative experiments were conducted at Kowie Point, where P. angulosus occurs in sympatry, The first, involved urchin removals from three experimental sites. The percentage cover of four functional algal groups was monitored in three experimental and three unaltered control sites over a three month period in spring (Sept. - Dec.) 1993. Two 100 point 0,25m² random point quadrats were thrown at each of the six sites at approximately monthly intervals over the experimental period. Since initial cover of algae varied at the six sites, ANOVA's of the change in percentage cover of four functional algal groups were used to determine treatment effects. No treatment effects were identified for any of the four functional algal groups. There was a strong negative correlation between the percentage cover of foliose algae and encrusting coralline algae, suggesting the possibility of a competitive relationship between them. The second, involved the experimental manipulation of microhabitat availability. The blocking of overhangs, by means of cement filled bags, resulted in an approximate 50% decrease in the total number of urchins in the two experimental pools, and the two control pools without overhangs. However, in the control pool with overhangs there was a slight increase in the number of urchins over the same period. Clearly, the presence of suitable shelters, is a prerequisite for the maintenance of dense intertidal population of P. angulosus. It is proposed that, due to the exposed nature of the South African coast, intertidal populations of P.angulosus are restricted to inhabiting suitable shelters from which they emerge to feed on passing drift algae. The implications of these findings are discussed in terms of current ecological literature.

Tropical forests play a major role in global carbon (C) dynamics and maintain some of the highest biological complexity on Earth; however, little is known about how variation in wood chemical traits contributes to tropical forest structure and function. This research examines inter- and intraspecific patterns in wood chemical traits in order to understand 1) the role wood chemical traits play in tropical forest C dynamics, and 2) the adaptive significance of wood chemical traits in tropical trees. I found wood C concentration varies widely among co-occurring tropical tree species, with average C concentration (47.4 ± 0.33% w/w (S.E.)) being significantly lower than values assumed in prominent forest C accounting protocols. Failing to account for this variation leads to overestimates of ~3.3 – 5.3% in tropical forest C accounting, an error that compounds significantly at larger spatial scales. I also show that oven drying samples prior to elemental analysis underestimates wood C concentration by 2.5 ± 0.17%, due to the loss of the “volatile C fraction”. Counter to expectations, I found wood C concentration is not ii phylogenetically conserved nor correlated to species demography or life history traits. Wood chemical traits showed consistent size-dependent patterns: wood C (in 16 of 24 species) and lignin (in 15 of 16 species) was higher in saplings vs. conspecific canopy trees. These patterns, complimented by phylogenetic analyses, suggest saplings require wood chemical traits that confer greater pathogen defense. When analyzed across a continuous size spectrum, I found wood C concentration (and leaf structural traits) increases linearly, while wood starch concentration (and leaf traits associated with C gain) shows “hump-shaped” patterns with peak values closely preceding reproductive onset; the latter result suggests C may limit growth in larger trees. Overall, my dissertation provides one of the first comprehensive examinations of wood chemical trait variation in tropical trees. In doing so it provides novel, timely, and critical insights into how wood chemical traits contribute to tropical forest structure and function.

The semicircular canals of the vestibular system detect angular head rotations and play a fundamental role in guiding motor reflexes during locomotor behaviors. While extensive research has documented the relationship between the semicircular canal shape (i.e. radius of curvature and canal length) and locomotor behaviors, levels of intraspecific variation in primates are relatively unknown. Predictive models using these metrics to reconstruct locomotion in extinct animals are generally based on one individual per species. Furthermore, the influence of body size and to a lesser degree brain size heavily influences overall canal morphology.

This study documents intraspecific variation in the size, shape and orientation of the semicircular canals in relation to changes in function, brain size, and body size via analysis of high resolution CT scans of large samples of extant primate species. I test the hypothesis that the extent of intraspecific variation differs across a sample of primates, reflecting the intensity of selective pressure on canal shape in species that require agility during locomotion. I also examine whether spatial constraints resulting from the size of the skull (reflected by the size of the brain) affect canal radii of curvature and canal orthogonality more strongly than observed agility during locomotion.

To this end, data was gathered from high-resolution CT images of museum specimens. For the comparative analysis, 14-matched pairs of adult extant primate species were selected that contrast in agility and brain size in closely related genera. CT images of these specimens were used to measure functional measures of canal sensitivity (e.g., canal radii of curvature, orthogonality). This data was used to test hypotheses concerning intraspecific and interspecific variation in semicircular canal functional morphology. This data was then combined with a larger mammalian dataset culled from the literature, to further test hypotheses relating to body-size and brain size dependent variation in individual canal metrics.

Evaluation of levels of intraspecific variation support the hypothesis put forth by Billet et al. (2012), that selection on canal morphology is relaxed in animals with slow locomotor behaviors, who are observed to have higher levels of intraspecific variation. Analyses of interspecific variation provides tentative support for the use of canal orthogonality in reconstructive models, most especially in canal angles that seem least effected by other constraints—brain size, etc. However, locomotor signals are complex and brain/skull interactions can potentially produce misleading results when reconstructing locomotor behaviors. This work highlights the importance of critically assessing comparative groups used for inferring behaviors in both extinct and extant animals.

Dissertation

This thesis deals with the relationship between the place of origin and the extend of cold hardiness of fire bug Pyrrhocoris apterus (Linnaeus, 1758). Thirteen populations from twelve European localities were used in the experiment. Linear regressions were used to relate the values of SCP (10th percentile, first quartile, mean and median) of the individual populations to minimum and average winter temperatures of given localities. The relationship between air temperatures and SCP values were significant provided that the data of all populations were used. After the removal of three southern non-diapausing populations this relationship lost its significance.

The thesis deals with phenotypic, ploidy and genetic variation of two Campanula species occurring in the Krkonoše Mts., namely the endemic C. bohemica and widespread C. rotundifolia subsp. rotundifolia. For comparative purposes subspecies sudetica of the latter species was also included. The main aim was to get insight into population structure and assess the threat of interspecific hybridization to the survival of the endemic bluebell. Flow cytometry, distance-based morphometrics and molecular analysis were used to address these questions. Three distinct groups of fluorescence intensities were revealed by flow cytometry, corresponding to DNA diploids, tetraploids and pentaploids. While diploids morphologically matched the nominate subspecies of C. rotundifolia, tetraploids corresponded either to C. rotundifolia subsp. sudetica or C. bohemica. Most populations from the Krkonoše Mts. were uniform although a sympatric growth of diploids and tetraploids was encountered in 12 populations. Only two pentaploids individuals, most likely of hybrid origin, were found, which indicated that interspecific hybridization is much less common than previously assumed. The two tetraploid taxa were distinguished by molecular markers. A combination of flow cytometry and molecular analyses thus allowed reliable...

碩士
國立臺灣海洋大學
海洋生物研究所
106
Horseshoe crabs are famous as being a living fossil and their blood is widely harvested for medical application. However, over-harvesting and degradation of habitat lead to the decline in horseshoe crab populations. To investigate the ecological niche and the behavior of horseshoe crab in wild, dietary research is a direction. In the present study, the diet composition of Asian horseshoe crab species were studied using molecular technique. The three Asian horseshoe crab species, Carcinoscorpius rotundicauda, Tachypleus gigas and T. tridentatus were collected from Japan, Taiwan, Hong Kong and Singapore. DNA were extracted from the content of intestine and gizzard. Nuclear 18S rRNA gene was amplified from the DNA extract with addition of peptide nucleic acid (PNA) blockers that inhibit amplification of horseshoe crab DNA so that only DNA of prey items were preferentially amplified. The results showed that the prey composition are different in the three species of horseshoe crabs. There were a large proportion of sea anemone and Bivalve in the diet of C. rotundicauda, and T. gigas mainly feed on Polychaeta. Moreover, the diet of T. tridentatus from Kinmen, Shuikou and Pak Nai were similar, mainly with Polychaeta and Oligochaeta. On the other hand, T. tridentatus from Kyushu has its diet consisting of more Bivalve and few Polychaeta. Diet composition from C. rotundicauda has prey composition very different from that find in habitat soil fauna, showing that this horseshoe crab has food selectivity. This is also the first study using DNA metabarcoding to analysis the dietary of horseshoe crabs and successfully detected gelatin prey (Cnidarian) from gut content and feces.