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1.
Ecol Evol ; 14(4): e11204, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38633521

RESUMO

Understanding the forces that shape population genetic structure is fundamental both for understanding evolutionary trajectories and for conservation. Many factors can influence the geographic distribution of genetic variation, and the extent to which local populations differ can be especially difficult to predict in highly mobile organisms. For example, many species of seabirds are essentially panmictic, but some show strong structure. Pigeon Guillemots (Cepphus columba; Charadriiformes: Alcidae) breed in small colonies scattered along the North Pacific coastline and feed in shallow nearshore waters year-round. Given their distribution, gene flow is potentially lower and population genetic structure is stronger than in most other high-latitude Northern Hemisphere seabirds. We screened variation in the mitochondrial control region, four microsatellite loci, and two nuclear introns in 202 Pigeon Guillemots representing three of five subspecies. Mitochondrial sequences and nuclear loci both showed significant population differences, although structure was weaker for the nuclear loci. Genetic differentiation was correlated with geographic distance between sampling locations for both the mitochondrial and nuclear loci. Mitochondrial gene trees and demographic modeling both provided strong evidence for two refugial populations during the Pleistocene glaciations: one in the Aleutian Islands and one farther east and south. We conclude that historical fragmentation combined with a stepping-stone model of gene flow led to the relatively strong population differentiation in Pigeon Guillemots compared to other high-latitude Northern Hemisphere seabird species. Our study adds to growing evidence that Pleistocene glaciation events affected population genetic structure not only in terrestrial species but also in coastal marine animals.

2.
Evol Lett ; 8(1): 56-63, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38370550

RESUMO

Because of ongoing rapid climate change, many ecosystems are becoming both warmer and more variable, and these changes are likely to alter the magnitude and variability of natural selection acting on wild populations. Critically, changes and fluctuations in selection can impact both population demography and evolutionary change. Therefore, predicting the impacts of climate change depends on understanding the magnitude and variation in selection on traits across different life stages and environments. Long-term experiments in wild settings are a great opportunity to determine the impact of environmental conditions on selection. Here we examined variability in the strength of selection on size traits of nestling black-legged kittiwakes (Rissa tridactyla) in a 25-year study including a food supplementation experiment on Middleton Island in the Gulf of Alaska. Using mixed effect models, we examined the annual variability of stage-specific and resource-specific selection gradients across 25 years. We found that (a) larger and heavier hatchlings were the most likely to survive during early ontogeny, (b) non-food supplemented younger nestlings in a brood experienced the strongest selection, and (c) warmer conditions increased the magnitude of selection on nestling mass and affected non-food supplemented and second-hatched nestlings the most. Our results suggested that variable resource dynamics likely caused some of the changes in selection from year to year and that warming conditions increased the strength of selection on subarctic seabird growth. However, our experimental manipulation revealed that local environmental heterogeneity could buffer the selection expected from broader climatic changes. Consequently, understanding the interactive effects of local conditions and general changes in climate seems likely to improve our ability to predict future selection gradients.

3.
Sci Rep ; 13(1): 13692, 2023 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-37608061

RESUMO

Annual cues in the environment result in physiological changes that allow organisms to time reproduction during periods of optimal resource availability. Understanding how circadian rhythm genes sense these environmental cues and stimulate the appropriate physiological changes in response is important for determining the adaptability of species, especially in the advent of changing climate. A first step involves characterizing the environmental correlates of natural variation in these genes. Band-rumped and Leach's storm-petrels (Hydrobates spp.) are pelagic seabirds that breed across a wide range of latitudes. Importantly, some populations have undergone allochronic divergence, in which sympatric populations use the same breeding sites at different times of year. We investigated the relationship between variation in key functional regions of four genes that play an integral role in the cellular clock mechanism-Clock, Bmal1, Cry2 and Per2-with both breeding season and absolute latitude in these two species complexes. We discovered that allele frequencies in two genes, Clock and Bmal1, differed between seasonal populations in one archipelago, and also correlated with absolute latitude of breeding colonies. These results indicate that variation in these circadian rhythm genes may be involved in allochronic speciation, as well as adaptation to photoperiod at breeding locations.


Assuntos
Fatores de Transcrição ARNTL , Clima , Estações do Ano , Aclimatação , Ritmo Circadiano/genética
4.
J Hered ; 114(5): 459-469, 2023 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-37162284

RESUMO

The Bermuda petrel Pterodroma cahow is an island endemic seabird that belongs to the Procellariiformes, one of the most endangered orders of birds. Historical records suggest a significant population size decline following human settlement in Bermuda, bringing the species to near extinction. Since the 1950s, the population has been recovering aided by the implementation of an ongoing conservation plan. However, it still faces several threats, and negative genetic effects resulting from that drastic decline are to be expected, including inbreeding and genetic drift. We studied genetic diversity and levels of inbreeding, and their effects on individual fitness and mating choice. We also tested for a genetic signature of the recent demographic bottleneck. For this, we analyzed variation in thousands of nuclear single-nucleotide polymorphisms derived from double digest restriction site-associated DNA sequencing and 1 mitochondrial gene (cytochrome oxidase I). The results revealed that the Bermuda petrel suffered a recent genetic bottleneck and shows low mitochondrial diversity compared with other petrel species. Conversely, nuclear diversity was similar to that of other endangered petrels. Inbreeding levels were not high overall, although some individuals were highly inbred. However, we found no evidence that individual inbreeding or relatedness between mates affected hatching success, or that mate choice is influenced by kinship in this very small population.


Assuntos
Variação Genética , Depressão por Endogamia , Humanos , Animais , Bermudas , Aves/genética , Endogamia , Espécies em Perigo de Extinção
5.
Oecologia ; 198(2): 307-318, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34657179

RESUMO

Predicting the impacts of changing environments on phenotypes in wild populations remains a challenge. Growth, a trait that frequently influences fitness, is difficult to study as it is influenced by many environmental variables. To address this, we used a sliding window approach to determine the time windows when sea-surface and air temperatures have the potential to affect growth of black-legged kittiwakes (Rissa tridactyla) on a colony in the Northeast Pacific. We examined environmental drivers influencing nestling growth using data from a long-term (21-year) study, that food supplements a portion of the colony. The associations between kittiwake growth and climatic conditions in our study indicated that warmer environmental conditions can both positively and negatively impact nestling growth parameters depending on hatching order. We found that first-hatched nestlings had a heavier maximum mass under warm air temperatures and cold sea conditions. Warmer air temperatures negatively affected the second-hatched nestling in a brood. However, when air temperatures were warm, warmer sea-surface temperatures predicted heavy, fast-growing second-hatched nestlings in contrast to what we observed for first-hatched nestlings. Food supplementation alleviated the temperature effects, and competition among nestlings influenced how strongly a variable affected growth. We identified windows that might indicate specific biological pathways through which environmental variation affected growth directly or indirectly. Overall, our windows suggest that nestlings in shared nests will be most affected by warming conditions.


Assuntos
Charadriiformes , Animais , Alimentos , Estações do Ano
6.
Biol Rev Camb Philos Soc ; 95(3): 625-651, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32022401

RESUMO

Elucidating the factors underlying the origin and maintenance of genetic variation among populations is crucial for our understanding of their ecology and evolution, and also to help identify conservation priorities. While intrinsic movement has been hypothesized as the major determinant of population genetic structuring in abundant vagile species, growing evidence indicates that vagility does not always predict genetic differentiation. However, identifying the determinants of genetic structuring can be challenging, and these are largely unknown for most vagile species. Although, in principle, levels of gene flow can be inferred from neutral allele frequency divergence among populations, underlying assumptions may be unrealistic. Moreover, molecular studies have suggested that contemporary gene flow has often not overridden historical influences on population genetic structure, which indicates potential inadequacies of any interpretations that fail to consider the influence of history in shaping that structure. This exhaustive review of the theoretical and empirical literature investigates the determinants of population genetic differentiation using seabirds as a model system for vagile taxa. Seabirds provide a tractable group within which to identify the determinants of genetic differentiation, given their widespread distribution in marine habitats and an abundance of ecological and genetic studies conducted on this group. Herein we evaluate mitochondrial DNA (mtDNA) variation in 73 seabird species. Lack of mutation-drift equilibrium observed in 19% of species coincided with lower estimates of genetic differentiation, suggesting that dynamic demographic histories can often lead to erroneous interpretations of contemporary gene flow, even in vagile species. Presence of land across the species sampling range, or sampling of breeding colonies representing ice-free Pleistocene refuge zones, appear to be associated with genetic differentiation in Tropical and Southern Temperate species, respectively, indicating that long-term barriers and persistence of populations are important for their genetic structuring. Conversely, biotic factors commonly considered to influence population genetic structure, such as spatial segregation during foraging, were inconsistently associated with population genetic differentiation. In light of these results, we recommend that genetic studies should consider potential historical events when identifying determinants of genetic differentiation among populations to avoid overestimating the role of contemporary factors, even for highly vagile taxa.


Assuntos
Aves/genética , Variação Genética , Distribuição Animal/fisiologia , Migração Animal/fisiologia , Animais , Aves/classificação , DNA Mitocondrial/genética , Ecossistema , Fluxo Gênico , Frequência do Gene , Genética Populacional , Oceanos e Mares , Filogenia
7.
Evol Appl ; 12(8): 1505-1512, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31462910

RESUMO

Genetic variation is fundamental to population fitness and adaptation to environmental change. Human activities are driving declines in many wild populations and could have similar effects on genetic variation. Despite the importance of estimating such declines, no global estimate of the magnitude of ongoing genetic variation loss has been conducted across species. By combining studies that quantified recent changes in genetic variation across a mean of 27 generations for 91 species, we conservatively estimate a 5.4%-6.5% decline in within-population genetic diversity of wild organisms since the industrial revolution. This loss has been most severe for island species, which show a 27.6% average decline. We identified taxonomic and geographical gaps in temporal studies that must be urgently addressed. Our results are consistent with single time-point meta-analyses, which indicated that genetic variation is likely declining. However, our results represent the first confirmation of a global decline and provide an estimate of the magnitude of the genetic variation lost from wild populations.

8.
Mol Phylogenet Evol ; 139: 106552, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31278983

RESUMO

Humans are inherently biased towards naming species based on morphological differences, which can lead to reproductively isolated species being mistakenly classified as one if they are morphologically similar. Recognising cryptic diversity is needed to understand drivers of speciation fully, and for accurate estimates of global biodiversity and assessments for conservation. We investigated cryptic species across the range of band-rumped storm-petrels (Hydrobates spp.): highly pelagic, nocturnal seabirds that breed on tropical and sub-tropical islands in the Atlantic and Pacific Oceans. In many breeding colonies, band-rumped storm-petrels have sympatric but temporally isolated (allochronic) populations; we sampled all breeding locations and allochronic populations. Using mitochondrial control region sequences from 754 birds, cytochrome b sequences from 69 birds, and reduced representation sequencing of the nuclear genomes of 133 birds, we uncovered high levels of genetic structuring. Population genomic analyses revealed up to seven unique clusters, and phylogenomic reconstruction showed that these represent seven monophyletic groups. We uncovered up to six independent breeding season switches across the phylogeny, spanning the continuum from genetically undifferentiated temporal populations to full allochronic species. Thus, band-rumped storm-petrels encompass multiple cryptic species, with non-geographic barriers potentially comprising strong barriers to gene flow.


Assuntos
Charadriiformes/classificação , Filogenia , Animais , Oceano Atlântico , Teorema de Bayes , Biodiversidade , Cruzamento , Charadriiformes/genética , DNA Mitocondrial/genética , Fluxo Gênico , Genética Populacional , Geografia , Funções Verossimilhança , Mitocôndrias/genética , Oceano Pacífico , Análise de Componente Principal , Especificidade da Espécie
9.
Mol Ecol Resour ; 18(1): 79-90, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28815912

RESUMO

Thanks to a dramatic reduction in sequencing costs followed by a rapid development of bioinformatics tools, genome assembly and annotation have become accessible to many researchers in recent years. Among tetrapods, birds have genomes that display many features that facilitate their assembly and annotation, such as small genome size, low number of repeats and highly conserved genomic structure. However, we found that high genomic heterozygosity could have a great impact on the quality of the genome assembly of the thick-billed murre (Uria lomvia), an arctic colonial seabird. In this study, we tested the performance of three genome assemblers, ray/sscape, soapdenovo2 and platanus, in assembling the highly heterozygous genome of the thick-billed murre. Our results show that platanus, an assembler specifically designed for heterozygous genomes, outperforms the other two approaches and produces a highly contiguous (N50 = 15.8 Mb) and complete genome assembly (93% presence of genes from the Benchmarking Universal Single Copy Ortholog [BUSCO] gene set). Additionally, we annotated the thick-billed murre genome using a homology-based approach that takes advantage of the genomic resources available for birds and other taxa. Our study will be useful for those researchers who are approaching assembly and annotation of highly heterozygous genomes, or genomes of species of conservation concern, and/or who have limited financial resources.


Assuntos
Charadriiformes/genética , Biologia Computacional/métodos , Genoma , Heterozigoto , Anotação de Sequência Molecular/métodos , Animais
10.
Mol Ecol ; 26(13): 3330-3342, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28370658

RESUMO

The importance of sympatric speciation - the evolution of reproductive isolation between codistributed conspecific individuals - in generating biodiversity is highly controversial. Allochrony, or differences in breeding time (phenology) between conspecific individuals, has the potential to lead to reproductive isolation and therefore speciation. We critically review the literature to test the importance of allochronic speciation over the three timescales over which allochrony can occur - over the day, between seasons or between years - and explore what is known about genomic mechanisms underlying allochrony in the diverse taxa in which it is found. We found that allochrony can be a key contributor to reproductive isolation, especially if populations have little overlap in breeding time and therefore little potential for gene flow, and may sometimes be the initial or key driver of speciation. Shifts in phenology can be caused by several factors, including a new ecological opportunity, environmental change, or reinforcement. The underlying genomic basis of allochrony has been studied mostly in insects, highlighting the need for genomic studies in other taxa; nonetheless, results to date indicate that several cases of allochrony involve changes in circadian genes. This review provides the first comprehensive discussion of the role of allochrony in speciation and demonstrates that allochrony as a contributor to divergence may be more widespread than previously thought. Understanding genomic changes and adaptations allowing organisms to breed at new times may be key in the light of phenological changes required under climate change.


Assuntos
Especiação Genética , Simpatria , Fatores de Tempo , Animais , Biodiversidade , Cruzamento , Relógios Circadianos/genética , Mudança Climática , Fluxo Gênico , Isolamento Reprodutivo , Estações do Ano
11.
Ecol Evol ; 7(7): 2370-2381, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28405300

RESUMO

Investigating the extent (or the existence) of local adaptation is crucial to understanding how populations adapt. When experiments or fitness measurements are difficult or impossible to perform in natural populations, genomic techniques allow us to investigate local adaptation through the comparison of allele frequencies and outlier loci along environmental clines. The thick-billed murre (Uria lomvia) is a highly philopatric colonial arctic seabird that occupies a significant environmental gradient, shows marked phenotypic differences among colonies, and has large effective population sizes. To test whether thick-billed murres from five colonies along the eastern Canadian Arctic coast show genomic signatures of local adaptation to their breeding grounds, we analyzed geographic variation in genome-wide markers mapped to a newly assembled thick-billed murre reference genome. We used outlier analyses to detect loci putatively under selection, and clustering analyses to investigate patterns of differentiation based on 2220 genomewide single nucleotide polymorphisms (SNPs) and 137 outlier SNPs. We found no evidence of population structure among colonies using all loci but found population structure based on outliers only, where birds from the two northernmost colonies (Minarets and Prince Leopold) grouped with birds from the southernmost colony (Gannet), and birds from Coats and Akpatok were distinct from all other colonies. Although results from our analyses did not support local adaptation along the latitudinal cline of breeding colonies, outlier loci grouped birds from different colonies according to their non-breeding distributions, suggesting that outliers may be informative about adaptation and/or demographic connectivity associated with their migration patterns or nonbreeding grounds.

12.
Mol Ecol ; 25(10): 2144-64, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26946320

RESUMO

Gene flow is a fundamental evolutionary force in adaptation that is especially important to understand as humans are rapidly changing both the natural environment and natural levels of gene flow. Theory proposes a multifaceted role for gene flow in adaptation, but it focuses mainly on the disruptive effect that gene flow has on adaptation when selection is not strong enough to prevent the loss of locally adapted alleles. The role of gene flow in adaptation is now better understood due to the recent development of both genomic models of adaptive evolution and genomic techniques, which both point to the importance of genetic architecture in the origin and maintenance of adaptation with gene flow. In this review, we discuss three main topics on the genomics of adaptation with gene flow. First, we investigate selection on migration and gene flow. Second, we discuss the three potential sources of adaptive variation in relation to the role of gene flow in the origin of adaptation. Third, we explain how local adaptation is maintained despite gene flow: we provide a synthesis of recent genomic models of adaptation, discuss the genomic mechanisms and review empirical studies on the genomics of adaptation with gene flow. Despite predictions on the disruptive effect of gene flow in adaptation, an increasing number of studies show that gene flow can promote adaptation, that local adaptations can be maintained despite high gene flow, and that genetic architecture plays a fundamental role in the origin and maintenance of local adaptation with gene flow.


Assuntos
Adaptação Fisiológica/genética , Evolução Biológica , Fluxo Gênico , Alelos , Animais , Genômica , Humanos , Modelos Genéticos , Plantas , Seleção Genética
13.
Mol Phylogenet Evol ; 98: 314-23, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26921843

RESUMO

The evolutionary mechanisms underlying the geographic distribution of gene lineages in the marine environment are not as well understood as those affecting terrestrial groups. The continuous nature of the pelagic marine environment may limit opportunities for divergence to occur and lineages to spatially segregate, particularly in highly mobile species. Here, we studied the phylogeography and historical demography of two tropically distributed, pelagic seabirds, the Madeiran Storm-petrel Oceanodroma castro, sampled in the Azores, Madeira, Galapagos and Japan, and its sister species Monteiro's Storm-petrel O. monteiroi (endemic to the Azores), using a multi-locus dataset consisting of 12 anonymous nuclear loci and the mitochondrial locus control region. Both marker types support the existence of four significantly differentiated genetic clusters, including the sampled O. monteiroi population and three populations within O. castro, although only the mitochondrial locus suggests complete lineage sorting. Multi-locus coalescent analyses suggest that most divergence events occurred within the last 200,000years. The proximity in divergence times precluded robust inferences of the species tree, in particular of the evolutionary relationships of the Pacific populations. Despite the great potential for dispersal, divergence among populations apparently proceeded in the absence of gene flow, emphasizing the effect of non-physical barriers, such as those driven by the paleo-oceanographical environments, philopatry and local adaptation, as important mechanisms of population divergence and speciation in highly mobile marine species. In view of the predicted climate change impacts, future changes in the demography and evolutionary dynamics of marine populations might be expected.


Assuntos
Biodiversidade , Aves/genética , Variação Genética/genética , Filogenia , Animais , Organismos Aquáticos/classificação , Organismos Aquáticos/genética , Açores , Aves/classificação , Núcleo Celular/genética , Mudança Climática , DNA Mitocondrial/genética , Equador , Voo Animal , Fluxo Gênico/genética , Genes Mitocondriais/genética , Japão , Filogeografia , Portugal
14.
J Hered ; 106(3): 238-46, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25825313

RESUMO

Quaternary glaciations affected the distribution of many species. Here, we investigate whether the Arctic represented a glacial refugium during the Last Glacial Maximum or an area of secondary contact following the ice retreat, by analyzing the genetic population structure of the thick-billed murre (Uria lomvia), a seabird that breeds throughout the North Atlantic, North Pacific and Arctic Oceans. The thick-billed murre is a species of socio-economic importance and faces numerous threats including hunting, oil pollution, gill netting, and climate change. We compared variation in the mitochondrial DNA (mtDNA) control region (n = 424), supplemented by 4 microsatellite loci (n = 445), among thick-billed murres sampled throughout their range. MtDNA data indicated that colonies comprise 4 genetically differentiated groups (Φst = 0.11-0.81): 1) Atlantic Ocean plus New Siberian Islands region, 2) Cape Parry, 3) Chukchi Sea, and 4) Pacific Ocean. Microsatellite variation differed between Atlantic and Pacific populations. Otherwise, little substructure was found within either ocean. Atlantic and Pacific populations appear to have been genetically isolated since the last interglacial period and should be considered separate evolutionary significant units for management. The Chukchi Sea and Cape Parry appear to represent areas of secondary contact, rather than arctic refugial populations.


Assuntos
Charadriiformes/genética , Variação Genética , Genética Populacional , Animais , Regiões Árticas , Mudança Climática , Conservação dos Recursos Naturais , DNA Mitocondrial/genética , Fluxo Gênico , Repetições de Microssatélites , Modelos Genéticos , Análise de Sequência de DNA
15.
Environ Sci Technol ; 49(2): 863-72, 2015 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-25514043

RESUMO

Migration patterns are believed to greatly influence concentrations of contaminants in birds due to accumulation in spatially and temporally distinct ecosystems. Two species of fish-eating birds, the Double-crested Cormorant (Phalacrocorax auritus) and the Caspian Tern (Hydroprogne caspia) breeding in Lake Ontario were chosen to measure the impact of overwintering location on mercury concentrations ([Hg]). We characterized (1) overwintering areas using stable isotopes of hydrogen (δ(2)H) and band recoveries, and (2) overwintering habitats by combining information from stable isotopes of sulfur (δ(34)S), carbon (δ(13)C), nitrogen (δ(15)N), and δ(2)H in feathers grown during the winter. Overall, overwintering location had a significant effect on [Hg]. Both species showed high [Hg] in (13)C-rich habitats. In situ production of Hg (e.g., through sulfate reducing bacteria in sediments) and allochthonous import could explain high [Hg] in birds visiting (13)C-rich habitats. Higher [Hg] were found in birds with high δ(2)H, suggesting that Hg is more bioavailable in southern overwintering locations. Hotspot maps informed that higher [Hg] in birds were found at the limit of their southeastern overwintering range. Mercury concentrations in winter feathers were positively related to predicted spatial pattern of [Hg] in fish using the National Descriptive Model of Mercury in Fish (NDMMF) based on bird spatial assignment (using δ(2)H). This study indicates that the overwintering location greatly influences [Hg].


Assuntos
Aves , Plumas/química , Lagos , Mercúrio/análise , Migração Animal , Animais , Isótopos de Carbono/análise , Dieta/veterinária , Ecossistema , Monitoramento Ambiental , Peixes , Isótopos de Nitrogênio/análise , Ontário , Estações do Ano , Isótopos de Enxofre/análise
16.
Environ Sci Technol ; 48(23): 13694-702, 2014 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-25380025

RESUMO

Many aquatic fish-eating birds migrate long distances and are exposed to different mercury concentrations ([Hg]) during their annual cycle. Here we examined the importance of migration on [Hg] in two colonial migratory fish-eating bird species. We determined temporal trends of [Hg] and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) during the annual cycle in Double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) breeding in Lake Ontario by a repeated sampling of breast feathers and blood from recaptured individuals. We found an effect of previous winter [Hg], species, sex, and location to explain variations of Hg at breeding sites. This suggests Hg carryover from winter to summer periods and that variations of [Hg] in the summer are partially explained by [Hg] in the winter. Carryover of Hg among seasons and slow changes in [Hg] over time were found especially for individuals in high winter exposure groups, suggesting a slow depuration rate and a fast uptake rate for both species. In contrast, stable isotope values rapidly switched to reach equilibrium at a similar midpoint regardless of winter habitat or diet suggesting minimal carryover of isotopic signatures. The potential of Hg carryover from wintering sites indicates that Hg concentrations in birds at a given time may be influenced by previous exposure from distant locations.


Assuntos
Migração Animal , Aves/fisiologia , Poluição Ambiental , Mercúrio/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Cruzamento , Ecossistema , Plumas/química , Feminino , Peixes , Masculino , Mercúrio/sangue , Ontário , Estações do Ano
17.
PLoS One ; 8(4): e62256, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23614045

RESUMO

Understanding the process of speciation requires understanding how gene flow influences divergence. Recent analyses indicate that divergence can take place despite gene flow and that the sex chromosomes can exhibit different levels of gene flow than autosomes and mitochondrial DNA. Using an eight marker dataset including autosomal, z-linked, and mitochondrial loci we tested the hypothesis that blue-footed (Sula nebouxii) and Peruvian (S. variegata) boobies diverged from their common ancestor with gene flow, paying specific attention to the differences in gene flow estimates from nuclear and mitochondrial markers. We found no gene flow at mitochondrial markers, but found evidence from the combined autosomal and z-linked dataset that blue-footed and Peruvian boobies experienced asymmetrical gene flow during or after their initial divergence, predominantly from Peruvian boobies into blue-footed boobies. This gene exchange may have occurred either sporadically between periods of allopatry, or regularly throughout the divergence process. Our results add to growing evidence that diverging species can remain distinct but exchange genes.


Assuntos
Núcleo Celular/genética , Charadriiformes/genética , Fluxo Gênico/genética , Loci Gênicos/genética , Variação Genética , Mitocôndrias/genética , Animais , Cruzamentos Genéticos , DNA Mitocondrial/genética , Geografia , Haplótipos/genética , Íntrons/genética , Modelos Genéticos , Peru , Probabilidade
18.
BMC Evol Biol ; 10: 14, 2010 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-20074358

RESUMO

BACKGROUND: Many population genetic and phylogenetic analyses of mitochondrial DNA (mtDNA) assume that mitochondrial genomes do not undergo recombination. Recently, concerted evolution of duplicated mitochondrial control regions has been documented in a range of taxa. Although the molecular mechanism that facilitates concerted evolution is unknown, all proposed mechanisms involve mtDNA recombination. RESULTS: Here, we document a duplication of a large region (cytochrome b, tRNAThr, tRNAPro, ND6, tRNAGlu and the control region) in the mitochondrial genome of three related seabird species. To investigate the evolution of duplicate control regions, we sequenced both control region copies (CR1 and CR2) from 21 brown (Sula leucogaster), 21 red-footed (S. sula) and 21 blue-footed boobies (S. nebouxii). Phylogenetic analysis suggested that the duplicated control regions are predominantly evolving in concert; however, approximately 51 base pairs at the 5' end of CR1 and CR2 exhibited a discordant phylogenetic signal and appeared to be evolving independently. CONCLUSIONS: Both the structure of the duplicated region and the conflicting phylogenetic signals are remarkably similar to a pattern found in Thalassarche albatrosses, which are united with boobies in a large clade that includes all procellariiform and most pelecaniform seabirds. Therefore we suggest that concerted evolution of duplicated control regions either is taxonomically widespread within seabirds, or that it has evolved many times.


Assuntos
Aves/genética , Evolução Molecular , Duplicação Gênica , Genoma Mitocondrial , Filogenia , Animais , Teorema de Bayes , DNA Mitocondrial/genética , Funções Verossimilhança , Alinhamento de Sequência , Análise de Sequência de DNA
19.
Mol Ecol Resour ; 10(2): 404-8, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21565039

RESUMO

This article documents the addition of 411 microsatellite marker loci and 15 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Acanthopagrus schlegeli, Anopheles lesteri, Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus oryzae, Aspergillus terreus, Branchiostoma japonicum, Branchiostoma belcheri, Colias behrii, Coryphopterus personatus, Cynogolssus semilaevis, Cynoglossus semilaevis, Dendrobium officinale, Dendrobium officinale, Dysoxylum malabaricum, Metrioptera roeselii, Myrmeciza exsul, Ochotona thibetana, Neosartorya fischeri, Nothofagus pumilio, Onychodactylus fischeri, Phoenicopterus roseus, Salvia officinalis L., Scylla paramamosain, Silene latifo, Sula sula, and Vulpes vulpes. These loci were cross-tested on the following species: Aspergillus giganteus, Colias pelidne, Colias interior, Colias meadii, Colias eurytheme, Coryphopterus lipernes, Coryphopterus glaucofrenum, Coryphopterus eidolon, Gnatholepis thompsoni, Elacatinus evelynae, Dendrobium loddigesii Dendrobium devonianum, Dysoxylum binectariferum, Nothofagus antarctica, Nothofagus dombeyii, Nothofagus nervosa, Nothofagus obliqua, Sula nebouxii, and Sula variegata. This article also documents the addition of 39 sequencing primer pairs and 15 allele specific primers or probes for Paralithodes camtschaticus.

20.
Mol Ecol Resour ; 9(3): 913-5, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-21564788

RESUMO

Primers were developed for 10 microsatellite loci for two species of Oceanodroma storm-petrels. Variability was tested in 27 O. castro and 22 O. monteiroi from the Azores, and 24 O. leucorhoa from Norway. At least six loci amplified reliably and were polymorphic in each species. The number of alleles per locus averaged 4.6, and observed heterozygosities averaged 0.41. Most primers also yielded polymerase chain reaction products in O. tethys, O. hornbyi and Pterodroma phaeopygia. These loci are being used to assay population genetic structure in storm-petrels.

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