Spatial variation in density of organisms can lead to challenges in estimation of population size. Associated vital rates responsible for this variation also may vary geographically and in response to local ecological conditions, with the result that subunits of a metapopulation may have different trajectories. Both temporal and spatial variation in population size occurs not only as a result of additions through birth and deletions through death, but also from gains and losses arising from immigration and emigration, respectively. Although virtually all organisms have evolved mechanisms for dispersal, the role of movement in population dynamics has received far less attention than have contributions from recruitment and losses to mortality. I used mark-recapture techniques to make inferences about the role of movement in local population dynamics of Rosss Goose (Chen rossii) colonies by estimating rates of movement between breeding subpopulations in the Queen Maud Gulf metapopulation. I also assessed decision-based philopatry (i.e., the role of previous nesting outcome; sensu Hoover 2003) and a potential cost of reproduction to female geese through experimental manipulation of nesting success. <p>Previous nest fate influenced intra-colony dispersal as failed nesters moved further between consecutive nest sites, but inter-colony movement was not affected by previous nest fate. Regardless of previous nest fate, Rosss Geese did not exhibit philopatry to nest sites, or to breeding territories, suggesting that philopatry occurs at a larger spatial scale. Breeding success accounted for a detectable, but only small amount of variation (<11%) in dispersal distance within colonies. I suggest that temporal variation in habitat availability favors flexibility in settling patterns by geese in a changing matrix of habitat availability, governed largely by receding snow cover. Such flexibility is necessary for nesting as early as possible, because recruitment is strongly linked to timing of breeding by arctic-nesting geese. Colonial philopatry may be important not only for favorable nesting but also for access to high-quality feeding areas adjacent to colonies. Such feeding areas represent a predictable food resource important not only to growing goslings, but also adult survival regardless of the outcome of their breeding attempt. <p>I concluded from experimental manipulation that successful reproduction was encumbered with a cost to survival of females. I argue that such a cost of breeding is more likely to be incurred when climatic conditions during incubation are harsh, and when the breeding population is larger. <p>I did not find evidence for geographic variation in survival, but rates of philopatry varied markedly among colonies. The substantial exchange of females among breeding colonies (1) underscores the potential for dispersal to alter breeding distribution, (2) demonstrates that the influence of immigration on colony-specific rates of population growth was nontrivial, and (3) provides behavioral evidence for extensive gene flow resulting from female dispersal. Estimates of emigration and survival from my studies were used in combination with those for fecundity parameters and colony-specific population growth rates (lambda) to interpolate the role of immigration from a simple balance equation. During years for which rates of movement were estimated, immigration constituted 9-20% of lambda at the Karrak Lake colony, suggesting that movement was an important contribution to population growth.

Grassland bird populations in North America are in steady decline. Despite declining faster and more consistently than any other group of birds, grassland songbird populations are relatively understudied and little is known about factors driving breeding-site philopatry and dispersal. Landscape and habitat composition may influence fidelity of grassland songbirds to a breeding area. As predicted by the theory of the <i>Ideal Free Distribution</i>, high-quality sites are likely to have a higher percentage of return breeders than low-quality sites because higher quality sites should have more or better-quality resources birds need for improved fitness. Using stable hydrogen isotope (äD) analysis, I approximated minimum fidelity rates of two grassland songbirds to two landscape (grass- vs crop-dominated landscapes) and two habitat (native grass vs planted grass) types. I hypothesized that grassland songbirds would return more readily to higher quality sites. For Spragues Pipit (<i>Anthus spragueii</i>), a habitat specialist, this would mean returning more readily to native grass habitat in grass dominated landscapes. I expected no difference in return rate of Savannah Sparrow (<i>Passerculus sandwichensis</i>), a habitat generalist, to either habitat or landscape. However, I found that the proportion of non-returning breeders was not influenced by landscape or habitat for either species. Furthermore, I examined attributes (distance from capture point to nearest crop and to the nearest road, as well as the percentage of native grass, planted grass, water and woody vegetation within landscape and territory buffers around the capture point) of the landscape and territory of each individual to determine if specific landscape or territory characteristics influenced their return rate to a breeding area. Neither species showed an affinity or aversion to any of the landscape or territory characteristics considered.<p> At a larger scale, geographical position within the breeding range may influence dispersal rates of migratory songbirds. Given that environmental factors often change in a clinal manner, central populations presumably experience the most favorable environmental conditions and peripheral populations the least favorable. Therefore, geographically peripheral locations likely occur in ecologically marginal or stressful conditions, resulting in higher dispersal rates of migratory birds. I examined the differences in dispersal rates of two grassland songbirds at two geographically distinct locations; one centrally located in the Spragues Pipit breeding range (Last Mountain Lake area, SK, Canada) and one at the periphery (Bowdoin National Wildlife Refuge, MT, USA). As expected, Spragues Pipits at the Bowdoin National Wildlife Refuge had a significantly larger dispersal rate than at the Last Mountain Lake area. Savannah Sparrow dispersal rates did not differ between locations at the more conservative outlier classification. These results provide some limited evidence that geographical position within the breeding range can influence dispersal rates.<p> Using äD analysis, I found that local amount-weighted growing-season deuterium in precipitation (äDp) at locations within grassland ecosystems differed from those long-term (45+ year) models described by stable hydrogen isotope ratio basemaps, illustrated in Hobson and Wassenaar (1997), Meehan et al. (2004) and Bowen et al. (2005). Therefore, I describe how äDp values were corrected from the long-term isoscape value predicted by Bowen et al. (2005). This method of determining year-specific local weighted growing-season äDp is an improvement upon the currently used Bowen et al. (2005) isoscape that is based on long-term precipitation patterns. To improve assignment of individuals to origins based on their äDf values, future research should incorporate year-to-year variation by applying year-specific corrections to the Bowen et al. (2005) isoscape.<p> More research is needed to determine the factors affecting the philopatry and dispersal of grassland songbirds in order to conserve them.

Orientador: Mateus José Rodrigues Paranhos da Costa / Banca: Reinaldo Otávio Alvarenga Alves de Brito / Banca: José Maurício Barbanti Duarte / Banca: Paulo Bahiense Ferraz Filho / Banca: Henrique Nunes de Oliveira / Resumo: Estudos recentes revelaram a estruturação de diversas populações de vertebrados a um nível local. Essa estruturação tem sido relacionada aos sistemas de acasalamento e padrões de filopatria-dispersão das espécies. Esse estudo objetivou estudar como a organização espacial contribui para a estruturação genética de uma população. Avaliamos os papéis da filopatria e da dispersão a partir do comportamento espacial e da estrutura genética de uma população de mouflons mediterrâneos. Localizações obtidas por radiotelemetria foram utilizadas para descrever o comportamento espacial de ambos os sexos durante o período reprodutivo. Fêmeas mostraram-se filopátricas e revelaram uma estruturação sócio-espacial em unidades de população. Parte dos machos manteve-se fiel ao domínio reprodutivo de um ano a outro, enquanto outros dispersaram para outro domínio. Domínios reprodutivos de machos não sobrepõem apenas uma unidade de fêmeas. Inferimos sobre os fluxos gênicos promovidos pelos machos que se deslocam entre as unidades, a partir do polimorfismo de microsatélites. O teste de Hardy-Weinberg sugeriu uma população em desequilíbrio. Os testes de diferenciação gênica e genotípica e o FST confirmaram a estruturação genética da população. Mas não houve perda de heterozigose a nível da população ou no interior das unidades. O comportamento individual dos animais aparece como um fator importante da estruturação genética da população. Fêmeas mostram-se fortemente filopátricas e a aleatoriedade dos acasalamentos parece assegurada por um sistema reprodutivo baseado na promiscuidade. O fluxo gênico é mantido pela dispersão de parte dos machos, mantendo a panmixia no interior das unidades / Abstract: Recent studies revealed the presence of fine-scale genetic structure in wild vertebrate populations. This structure has been related to breeding systems and specie's philopatry-dispersal pattern. The objective of this study was to examine how the spatial organization contributes to the genetic structure of a population. The role of philopatry and dispersion was evaluated from the spatial behaviour and genetic structure of a mouflon sheep population. Radio-tracking data was used to describe spatial behavior for both sexes during rut. Ewes were found to be partitioned in sociospatial units o which they were faithful. Movements patterns of rams were much more variable: some males remain faithful to the breeding area from one year to another, while others dispersed to other domain. Male rutting range can overlap more than once unit. We can infer about the male gene flow promoted by moving between the units from the polymorphism of microsatellites. Hardy-Weinberg test suggested disequilibrium in population. Genic and genotypic differentiation tests and FST confirmed the genetic structure of population. But there was no loss of heterozigosys neither at the population level nor within the units. The individual behavior of animals appears an important factor of population genetic structuring. Females are strongly phylopatrics. Randomness of matings would be assured by a reproductive system based on promiscuity. The gene flow between units and panmixia inside the units are maintained by some dispersal males / Doutor

Made available in DSpace on 2014-06-11T19:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-23Bitstream added on 2014-06-13T19:21:46Z : No. of bitstreams: 1 tercionetto_n_dr_jabo.pdf: 2777355 bytes, checksum: f61f3dfa0040cb7d42df00390237a91a (MD5) / Estudos recentes revelaram a estruturação de diversas populações de vertebrados a um nível local. Essa estruturação tem sido relacionada aos sistemas de acasalamento e padrões de filopatria-dispersão das espécies. Esse estudo objetivou estudar como a organização espacial contribui para a estruturação genética de uma população. Avaliamos os papéis da filopatria e da dispersão a partir do comportamento espacial e da estrutura genética de uma população de mouflons mediterrâneos. Localizações obtidas por radiotelemetria foram utilizadas para descrever o comportamento espacial de ambos os sexos durante o período reprodutivo. Fêmeas mostraram-se filopátricas e revelaram uma estruturação sócio-espacial em unidades de população. Parte dos machos manteve-se fiel ao domínio reprodutivo de um ano a outro, enquanto outros dispersaram para outro domínio. Domínios reprodutivos de machos não sobrepõem apenas uma unidade de fêmeas. Inferimos sobre os fluxos gênicos promovidos pelos machos que se deslocam entre as unidades, a partir do polimorfismo de microsatélites. O teste de Hardy-Weinberg sugeriu uma população em desequilíbrio. Os testes de diferenciação gênica e genotípica e o FST confirmaram a estruturação genética da população. Mas não houve perda de heterozigose a nível da população ou no interior das unidades. O comportamento individual dos animais aparece como um fator importante da estruturação genética da população. Fêmeas mostram-se fortemente filopátricas e a aleatoriedade dos acasalamentos parece assegurada por um sistema reprodutivo baseado na promiscuidade. O fluxo gênico é mantido pela dispersão de parte dos machos, mantendo a panmixia no interior das unidades / Recent studies revealed the presence of fine-scale genetic structure in wild vertebrate populations. This structure has been related to breeding systems and specie’s philopatry-dispersal pattern. The objective of this study was to examine how the spatial organization contributes to the genetic structure of a population. The role of philopatry and dispersion was evaluated from the spatial behaviour and genetic structure of a mouflon sheep population. Radio-tracking data was used to describe spatial behavior for both sexes during rut. Ewes were found to be partitioned in sociospatial units o which they were faithful. Movements patterns of rams were much more variable: some males remain faithful to the breeding area from one year to another, while others dispersed to other domain. Male rutting range can overlap more than once unit. We can infer about the male gene flow promoted by moving between the units from the polymorphism of microsatellites. Hardy-Weinberg test suggested disequilibrium in population. Genic and genotypic differentiation tests and FST confirmed the genetic structure of population. But there was no loss of heterozigosys neither at the population level nor within the units. The individual behavior of animals appears an important factor of population genetic structuring. Females are strongly phylopatrics. Randomness of matings would be assured by a reproductive system based on promiscuity. The gene flow between units and panmixia inside the units are maintained by some dispersal males

Cyclura ricordii is an endemic iguana from Hispaniola and is listed as Critically Endangered on the IUCN. The main threats are predation by introduced mammals, habitat destruction and hunting. The present study focused on two nesting areas in Pedernales in the Dominican Republic. The hypothesis tested is that natal philopatry influences dispersal and nest site selection. Monitoring and sampling took place during 2012-2013. Polymorphic markers were used to evaluate whether natal philopatry limits dispersal at multiple spatial scales. Ripley’s K, revealed that nests were significantly clustered. Hierarchical AMOVA revealed that nest site aggregations did not explain a significant portion of genetic variation. However, Mantel’s tests revealed significant positive correlations between genetic and geographic distance. These results indicate that natal philopatry limits dispersal at a course spatial scale, but does not influence nest site selection at a fine spatial scale.

No description available.

<p>This thesis focuses on a black-tailed godwit (<i>Limosa limosa</i>) population, consisting of 35-40 pairs, that breeds on a grazed shore meadow on SE Gotland, Sweden. The small size of the population makes it more prone to extinction due to chance events, than a larger population.</p><p>The godwits showed microhabitat preferences when choosing nest sites. Godwit nests had higher vegetation over the nest cup, lower surrounding (1-3 m) vegetation and different plant species composition, as compared to random sites. Breeding near conspecifics or other wader species, especially lapwings (<i>Vanellus vanellus</i>) and further away from potential predator perches were the most important factors in decreasing nest predation. A comparison between different shore meadows along the east coast of the island revealed that large, open areas suffered less from nest predation. Thus, shore meadows suitable for breeding godwits should be large and without trees or other predator perches and have a grazing regime that favours variation in vegetation height.</p><p>Over 80% of previously ringed adults returned each year, but very few birds ringed as chicks were recovered. Hatching success was 55-60% for all observed nests. To predict the future of the current population, demographic data were used in an ecological risk analysis. The simulations showed that the Gotlandic population will not survive the coming 40 years without immigration.</p><p>Black-tailed godwits are divided into three subspecies. Genetic analyses (mtDNA) revealed that all subspecies had unique haplotypes and there was a clear geographic structure among subspecies. Within the <i>limosa</i> subspecies, godwits on Gotland and Öland showed a high proportion of rare haplotypes, but no genetic variation was found in Dutch birds. These results imply that black-tailed godwits on Gotland and Öland have high conservation value.</p>

This thesis focuses on a black-tailed godwit (Limosa limosa) population, consisting of 35-40 pairs, that breeds on a grazed shore meadow on SE Gotland, Sweden. The small size of the population makes it more prone to extinction due to chance events, than a larger population. The godwits showed microhabitat preferences when choosing nest sites. Godwit nests had higher vegetation over the nest cup, lower surrounding (1-3 m) vegetation and different plant species composition, as compared to random sites. Breeding near conspecifics or other wader species, especially lapwings (Vanellus vanellus) and further away from potential predator perches were the most important factors in decreasing nest predation. A comparison between different shore meadows along the east coast of the island revealed that large, open areas suffered less from nest predation. Thus, shore meadows suitable for breeding godwits should be large and without trees or other predator perches and have a grazing regime that favours variation in vegetation height. Over 80% of previously ringed adults returned each year, but very few birds ringed as chicks were recovered. Hatching success was 55-60% for all observed nests. To predict the future of the current population, demographic data were used in an ecological risk analysis. The simulations showed that the Gotlandic population will not survive the coming 40 years without immigration. Black-tailed godwits are divided into three subspecies. Genetic analyses (mtDNA) revealed that all subspecies had unique haplotypes and there was a clear geographic structure among subspecies. Within the limosa subspecies, godwits on Gotland and Öland showed a high proportion of rare haplotypes, but no genetic variation was found in Dutch birds. These results imply that black-tailed godwits on Gotland and Öland have high conservation value.

Many sharks have life history characteristics (e.g., slow growth, late age at maturity, low fecundity, and long gestation periods) that make their populations vulnerable to collapse due to overfishing. The porbeagle (Lamna nasus), bull shark (Carcharhinus leucas), great hammerhead (Sphyrna mokarran), and smooth hammerhead (S. zygaena), are all commercially exploited. The population genetic structure of these species was assessed based on globally distributed sample sets using mitochondrial control region (mtCR) sequences and/or nuclear markers. Complex patterns of evolutionary and demographic history were inferred using coalescent and statistical moment-based methods. All four species showed statistically significant genetic partitioning on large scales, i.e., between hemispheres (L. nasus mtCR φST = 0.8273) or oceanic basins (C. leucas nuclear FST = 0.1564; S. mokarran mtCR φST = 0.8745, nuclear FST = 0.1113; S. zygaena mtCR φST = 0.8159, nuclear FST = 0.0495). Furthermore, S. zygaena mtCR sequences indicated statistically significant matrilineal genetic structuring within oceanic basins, but no intrabasin structure was detected with nuclear microsatellites. S. mokarran showed statistically significant genetic structure between oceanic basins with both nuclear and mitochondrial data, albeit with some differences between the two marker types in fine scale patterns involving northern Indian Ocean samples. A microsatellite assessment of C. leucas demonstrated no population structuring within the Atlantic or Indo-Pacific, with the exception that samples from Fiji were differentiated from the remaining Indo- Pacific Ocean locations. In contrast, the L. nasus mitochondrial and nuclear ITS2 sequences revealed strong northern vs. southern hemispheric population differentiation, but no differentiation within these hemispheres. These geographic patterns of genetic structure were used to determine the source of fins obtained from the international fin trade and to develop forensic tools for conservation.

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.