<p>The aim of this thesis is to study phylogeny, species-wide phylogeography and genetic diversity in <i>Formica</i> ants across Eurasia in connection with the history of biotic responses to Quaternary environmental changes.</p><p>The mitochondrial DNA phylogeny of Palaearctic <i>Formica</i> species supported the subgeneric grouping based on morphological similarity. The exception was that <i>F. uralensis</i> formed a separate phylogenetic group. The mitochondrial DNA phylogeny of the <i>F. rufa </i>group showed the division into three major phylogenetic groups: one with the species <i>F. polyctena</i> and <i>F. rufa</i>, one with <i>F. aquilonia</i>, <i>F. lugubris</i> and <i>F. paralugubris</i>, and the third one with <i>F. pratensis</i>.</p><p>West-east phylogeographic divisions were found in <i>F. pratensis</i> suggesting post-glacial colonization of western Europe and a wide area from Sweden to the Baikal Lake from separate forest refugia. In contrast, no phylogeographic divisions were detected in either <i>F. lugubris </i>or<i> F. exsecta</i>. Contraction of the distribution range to a single refugial area during the late Pleistocene and the following population expansion could offer a general explanation for the lack of phylogeographic structure across most of Eurasia in these species.</p><p>Sympatrically distributed and ecologically similar species <i>F. uralensis </i>and<i> F. candida</i> showed clear difference in the phylogeographic structure that reflected difference in their vicariant history. Whereas no phylogeographic divisions were detected in <i>F. uralensis</i> across Europe, <i>F. candida</i> showed a well-supported phylogeographic division between the western, the central and the southern group.</p><p>In socially polymorphic <i>F. cinerea</i>, the overall level of intrapopulation microsatellite diversity was relatively high and differentiation among populations was low, indicating recent historical connections. The lack of correspondence between genetic affinities and geographic locations of studied populations did not provide any evidence for differentiating between alternative hypotheses concerning the directions and sources of postglacial colonization of Fennoscandia.</p>

The aim of this thesis is to study phylogeny, species-wide phylogeography and genetic diversity in Formica ants across Eurasia in connection with the history of biotic responses to Quaternary environmental changes. The mitochondrial DNA phylogeny of Palaearctic Formica species supported the subgeneric grouping based on morphological similarity. The exception was that F. uralensis formed a separate phylogenetic group. The mitochondrial DNA phylogeny of the F. rufa group showed the division into three major phylogenetic groups: one with the species F. polyctena and F. rufa, one with F. aquilonia, F. lugubris and F. paralugubris, and the third one with F. pratensis. West-east phylogeographic divisions were found in F. pratensis suggesting post-glacial colonization of western Europe and a wide area from Sweden to the Baikal Lake from separate forest refugia. In contrast, no phylogeographic divisions were detected in either F. lugubris or F. exsecta. Contraction of the distribution range to a single refugial area during the late Pleistocene and the following population expansion could offer a general explanation for the lack of phylogeographic structure across most of Eurasia in these species. Sympatrically distributed and ecologically similar species F. uralensis and F. candida showed clear difference in the phylogeographic structure that reflected difference in their vicariant history. Whereas no phylogeographic divisions were detected in F. uralensis across Europe, F. candida showed a well-supported phylogeographic division between the western, the central and the southern group. In socially polymorphic F. cinerea, the overall level of intrapopulation microsatellite diversity was relatively high and differentiation among populations was low, indicating recent historical connections. The lack of correspondence between genetic affinities and geographic locations of studied populations did not provide any evidence for differentiating between alternative hypotheses concerning the directions and sources of postglacial colonization of Fennoscandia.

Gray hawks became established in the San Pedro River (SPR) valley in the mid-1900s following landscape changes that created habitat for them. The population of gray hawks along the SPR is at the northern edge of the species’ range, and its growth has been documented periodically since the 1970s. A study in the 1990s quantified gray hawk diet and habitat use in this area, and found that gray hawks hunt primarily in mesquite, eat mostly lizards, and that their productivity is positively correlated with the percentage of mesquite in their territories. The gray hawk population along the SPR has nearly doubled since the initial study was conducted, and pairs now nest in areas that contain little or no mesquite. Our main objectives were to determine whether: a) diet and habitat requirements have changed for gray hawks along the SPR since the population has as expanded, and b) productivity has declined as the population has expanded into habitats of potentially lower quality. We used nest cameras to document prey deliveries, and ESRI ArcGIS to quantify vegetation types within estimated home ranges of gray hawks. We compared productivity of gray hawk pairs in the 1990s and the 2010s, as well as the current productivity of pairs in territories that had been occupied by gray hawks in the 1990s (original territories) and those that only became occupied after the original study was completed (new territories). We found that that gray hawks used a wider variety of vegetation types, such as nest trees surrounded by grasslands, and consumed a wider variety of prey than they did in the 1990s, and that productivity remained constant over time. Like many populations at the edge of their range, the gray hawks that initially settled in the San Pedro River valley likely had access to only a portion of the resources that are common at the center of the species’ range, and therefore appeared to have a narrower set of diet and habitat requirements than the species as a whole. Areas that are currently being used by gray hawks for nesting (e.g., nest trees surrounded by grasslands) were likely unsuitable in the 1990’s because they were being used for agriculture and grazing. The two chapters of this thesis will be submitted to journals for publication and therefore contain overlapping information.

The population genetic structure of Atlantic yellowfin tuna (Thunnus albacares) has received little attention despite the substantial fishing mortality of juveniles caused by purse seining around fish aggregating devices in the Gulf of Guinea targeting multi-species schools that also include similarly sized skipjack tuna (Katsuwonus pelamis) and bigeye tuna (T. obesus). We used sequence data from 355 bp of the mitochondrial control region I as well as six microsatellite loci to examine: (1) population structure, and (2) to look for evidence of reproductive variance. We analyzed two samples of adults from the Gulf of Mexico (GOM) and one sample of early juveniles (20-50 mm) from the Gulf of Guinea (GOG). We found no evidence of geographic or temporal differentiation among the samples. Accordingly, the null hypothesis of panmixia for yellowfin tuna in the Atlantic Ocean could not be rejected. A sudden expansion analysis based on mtDNA control region I sequence data of yellowfin tuna was highly significant. Time estimates for expansion were between 40,000 and 80,000 years before present. The associated high levels of homoplasy could be masking any existing population structure. Additional sampling from additional locations and across several years will be needed to test the hypothesis of panmixia. We also provide preliminary evidence of the Allendorf-Phelps effect, which may contribute to reproductive variance. This is the first evidence of this effect in any other tuna or pelagic species. Data indicates that early juveniles sharing the same mtDNA control region I haplotype were caught in the same tow and had a significant probability of halfsibship status as calculated from their haplotype and genotype at one microsatellite locus through kinship analysis. Sampling throughout the spawning season and across several years, as well as analysis with additional microsatellite loci that have a more even distribution of alleles, will be needed to more fully identify the sibling status of larvae and early juveniles caught in the same tow as well as the extent of this reproductive variance.

The population genetic structure of Atlantic yellowfin tuna (Thunnus albacares) has received little attention despite the substantial fishing mortality of juveniles caused by purse seining around fish aggregating devices in the Gulf of Guinea targeting multi-species schools that also include similarly sized skipjack tuna (Katsuwonus pelamis) and bigeye tuna (T. obesus). We used sequence data from 355 bp of the mitochondrial control region I as well as six microsatellite loci to examine: (1) population structure, and (2) to look for evidence of reproductive variance. We analyzed two samples of adults from the Gulf of Mexico (GOM) and one sample of early juveniles (20-50 mm) from the Gulf of Guinea (GOG). We found no evidence of geographic or temporal differentiation among the samples. Accordingly, the null hypothesis of panmixia for yellowfin tuna in the Atlantic Ocean could not be rejected. A sudden expansion analysis based on mtDNA control region I sequence data of yellowfin tuna was highly significant. Time estimates for expansion were between 40,000 and 80,000 years before present. The associated high levels of homoplasy could be masking any existing population structure. Additional sampling from additional locations and across several years will be needed to test the hypothesis of panmixia. We also provide preliminary evidence of the Allendorf-Phelps effect, which may contribute to reproductive variance. This is the first evidence of this effect in any other tuna or pelagic species. Data indicates that early juveniles sharing the same mtDNA control region I haplotype were caught in the same tow and had a significant probability of halfsibship status as calculated from their haplotype and genotype at one microsatellite locus through kinship analysis. Sampling throughout the spawning season and across several years, as well as analysis with additional microsatellite loci that have a more even distribution of alleles, will be needed to more fully identify the sibling status of larvae and early juveniles caught in the same tow as well as the extent of this reproductive variance.

Made available in DSpace on 2016-06-02T20:21:22Z (GMT). No. of bitstreams: 1 2680.pdf: 6485015 bytes, checksum: 80308a62623a9b81cad38c987461252a (MD5) Previous issue date: 2009-09-24 / Universidade Federal de Minas Gerais / The present work studied populations of Ardea alba egretta (Great Egret) family Ardeidae (Aves), sampled from four Brazilian regions situated at different latitudes (Rio Grande do Sul, Pantanal, São Paulo and Amapá). Species-specific primers developed in this study allowed the sequencing of 194 individuals in the Domain I of mitochondrial DNA control region (fragment of 586 bp). Fifty-eight polymorphic sites were found, defining 74 haplotypes. Haplotype Hap9 was the most frequent and the majority of the remaining haplotypes occurred in low frequencies. Average nucleotide diversity was 0.006 and average haplotype diversity 0.908. Distribution of nucleotide diversity followed a descending order: Amapá> Pantanal> São Paulo> Rio Grande do Sul, and the differences between Amapá and the other populations were statistically significant. Results of AMOVA analysis indicated that there is genetic differentiation among populations of the four regions (Fct = 0.02145, p = 0.03324). Values of the pairwise F-statistics showed low genetic structuring among the colonies within each region, but significant structuring among the four regions. It was evident by the analysis of structuring that the genetic composition of Amapá is different from other regions. Significant differences revealed by the tests of Fu's Fs, Tajima's D, R2 and analyses of mismatch distribution, together with star-shaped haplotype networks, indicated signals of demographic expansion in the populations of Rio Grande do Sul and Pantanal. For the Amapá population only biases of Fu's Fs were significant and the curves of "mismatch distribution" can be explained by the unimodal standard distribution. The estimated time of expansion (&#964;) for Rio Grande do Sul population was 7,195 years before present, for Pantanal population was 32,009 and for Amapá population was 68,674. Obtained results are consistent with the hypothesis that the equatorial region likely was a refuge for populations of this species during the Pleistocene glaciations. / Foram estudadas populações de Ardea alba egretta (garça-branca-grande) da família Ardeidae (Aves), amostradas em quatro regiões brasileiras, com latitudes diferentes (Rio Grande do Sul, Pantanal, São Paulo e Amapá). Oligonucleotídeos espécie-específicos desenvolvidos nesse estudo possibilitaram o seqüenciamento de um fragmento de 586 pb do Domínio I da região controladora do DNA mitocondrial em 194 individuos. Cinqüenta e oito sítios polimórficos foram encontrados, definindo 74 haplótipos. O haplótipo de maior freqüência foi o Hap9 e a maioria dos demais haplótipos apresentaram freqüências baixas. A diversidade nucleotídica média foi de 0,006 e a diversidade haplotípica média 0,908. A distribuição da diversidade nucleotídica seguiu ordem decrescente do Amapá > Pantanal > São Paulo > Rio Grande do Sul e as diferenças entre Amapá e as demais populações foram estatisticamente significativas. Os resultados da análise AMOVA indicaram que há diferenciação genética entre as populações das quatro regiões (Fct = 0,02145; p = 0,03324). Valores de Fst par-a-par revelaram baixa estruturação entre as colônias dentro de cada região, mas estruturação entre as quatro regiões foi detectada. Ficou evidente pelas análises de estruturação que a composição genética do Amapá difere das demais regiões estudadas. Significantes desvios nos testes de Fs de Fu, D de Tajima, R2 e as análises da distribuição das diferenças par-a-par ( mismatch distribution ) e redes haplotípicas em formato de estrela apontam para sinais de expansão demográfica nas populações do Rio Grande do Sul e do Pantanal. Para o Amapá apenas os desvios de Fs de Fu foram significativos e as curvas de mismatch distribution podem ser explicadas pelo padrão unimodal. A estimativa do tempo de expansão (&#964;) para o Rio Grande do Sul foi de 7.195 anos antes do presente, para o Pantanal foi de 32.009 e para o Amapá foi de 68.674, anos antes do presente. Os resultados obtidos foram concordantes com a hipótese de que a região equatorial possivelmente foi o refúgio para as populações dessa espécie durante glaciações ocorridas no Pleistoceno.

Boreal forests are particularly vulnerable to climate change, experiencing a much more drastic increase in temperatures and having a limited amount of more northern refugia. The trees making up these vast and important ecosystems already had to adapt previously to environmental pressures brought about by the repeated glaciations during past ice ages. Studying the patterns of adaption of these trees can thus provide valuable insights on how to mitigate future damage. This thesis presents and analyses population structure, demo- graphic history and the distribution of fitness effects (DFE) of the diploid Betula pendula and tetraploid B. pubescens across Scandinavia. Birches–being widespread in boreal forests as well as having great economical importance–constitute superb model species. The analyses of this work confirm the expectations on postglacial population expansion and diploid-tetraploid introgression. They furthermore ascertain the presence of two genetic clusters and a remarkably similar DFE for the species. This work also contributes with a transparent, reproducible and reusable pipeline which facilitates running similar analyses for related species.