Variabilidade genética de Conopophaga lineata (Conopophagidae) em fragmentos florestais da Mata Atlântica

ABSTRACT: Forest fragmentation affects bird populations in many ways, modifying the composition of communities and favouring open country species. The Atlantic Forest is considered one of the most important biomes in the world, due to its great biodiversity, accelerated rates of deforestation, and high endemism. Despite these characteristics, few studies have evaluated the effects of forest fragmentation in the genetic structure of Atlantic forest bird populations. So, this study aims to verify the effects of forest fragmentation in the genetic population structure of Conopophaga lineata, through RAPD markers. To achieve this goal, 89 C. lineata individuals were captured in nine Atlantic Forest fragments in Minas Gerais State. The RAPD data indicate that forest fragmentation has not affected the genetic variation of C. lineata populations (Mann-Whitney U = 3.50; p = 0.11). Great part of the genetic variability of this species is found within populations and it was not observed a correlation between genetic and geographic distance (Mantel test t = 0.6250; p = 073). UPGMA analyses did not show defined clades and all branches showed low statistical support. The low population differentiation observed in this species can be due to a high gene flow among populations or a recent fragmentation. Thus, the current diversity status of C. lineata populations indicates that this species is not significantly affected by fragmentation. However, more genetic studies are essential to improve conservation strategies of Brazilian Atlantic Forest birds. __________________________________________________________________________________ RESUMOA fragmentação florestal afeta populações de aves de muitas maneiras, modificando a composição das comunidades e favorecendo espécies de áreas abertas. A Mata Atlântica é considerada um dos biomas mais importantes do mundo, devido à sua grande biodiversidade, aos altos níveis endemismo e de desmatamento. Apesar destas características, poucos estudos avaliaram os efeitos da fragmentação florestal na estrutura genética de populações de aves desse ecossistema. Dessa forma, este estudo visa verificar os efeitos da fragmentação florestal na variabilidade genética de Conopophaga lineata, através de marcadores RAPD. Assim, foram capturados 89 indivíduos de C. lineata em nove fragmentos florestais da Mata Atlântica do Estado de Minas Gerais. Os dados de RAPD indicam que a fragmentação florestal não afetou a variabilidade genética de Conopophaga lineata (Mann-Whitney U = 3,50; p = 0,11). Grande parte da variabilidade dessa espécie se encontra dentro das populações e não foi observada correlação entre a distância geográfica e a distância genética (Teste de Mantel t = 0,6250; p = 0.73). A análise UPGMA não mostrou clados definidos e todos os ramos apresentaram baixo suporte estatístico. A reduzida diferenciação populacional observada nessa espécie pode ser devida a intenso fluxo gênico entre as populações ou à recente fragmentação na região. Assim, a situação atual das populações de C. lineata indica que essa espécie não é significativamente afetada pela fragmentação. Entretanto, futuros estudos genéticos são essenciais para melhorar as estratégias de conservação da avifauna da Mata Atlântica do Brasil

Breeding biology, population structure and genetic variability of Larus dominicanus

Larus dominicanus é uma espécie de ampla distribuição no Hemisfério Sul, que se reproduz em ilhas próximas ao continente. Esta espécie vem apresentando grande expansão populacional nas últimas décadas, devido ao seu hábito generalista e sua alta capacidade competitiva. O crescimento de sua população tem causado o deslocamento de diversas outras espécies de aves e mamíferos marinhos de seus sítios reprodutivos, devido ao constante impacto da predação e parasitismo. Todas essas características tem feito com que muitos pesquisadores considerem essa espécie como uma praga nos ambientes costeiros. Dessa forma, estudos que busquem compreender biologia e evolução são fundamentais para a criação de futuros planos de manejo e conservação da assembléia de aves marinhas na costa brasileira. O presente estudo teve como objetivo caracterizar a biologia reprodutiva de L. dominicanus, buscando determinar seu sucesso reprodutivo. Bem como avaliar a razão sexual de suas populações ao longo da costa brasileira e estimar a variabilidade genética de suas populações no litoral do Brasil. Para isto estudamos a biologia reprodutiva dessa espécie em uma colônia do estado de São Paulo. Observamos que L. dominicanus apresenta alto sucesso reprodutivo, cerca 70% dos ovos eclodiram e cerca de 50% dos filhotes sobreviveram até a fase de vôo. Os filhotes apresentaram um rápido crescimento, em 30 dias já estão grande o suficiente para voarem, o que os tornam aptos a escaparem os predadores. Os principais predadores dessa espécie no estado de São Paulo são os urubus, sendo a fase mais suceptível aos ataques foram a fase de ovo e os primeiros 15 dias de vida dos filhotes. Dessa forma, com uma sobrevivência de 50% dos filhotes e baixa predação após a fase de vôo, as populações de L. dominicanus potencialmente podem apresentar grandes incrementos populacionais a cada ano. A razão sexual secundária para todas as populações amostradas ao longo do litoral brasileiro não apresentaram desvio da proporção 1:1 . Isso indica que as populações de L. dominicanus devem estar estáveis, o que é esperado de populações que se reproduzem em sítos com boas condições ambientais. De forma que, os pais não precisam favorecer o sexo que apresenta menor custo reprodutivo, levando ao desvio da razão sexual. Dentro deste panorama de grande sucesso reprodutivo e proporção similar de machos e fêmeas em uma espécie de ampla distribuição geográfica, como L. dominicanus, esperávamos encontrar grande variabilidade genética dentro e entre suas 13 populações. Entretanto, os resultados do presente estudo relativos a marcadores do DNA mitocondrial revelaram um cenário oposto. Estudando dois genes mitocondriais (citb e ATPase 8 e 6) foi observado que ao longo de toda a costa brasileira a diversidade genética desse grupo foi praticamente nula. Encontramos um único haplótipo para o citocromo b e dois haplótipos para a ATPase 8 e 6 que se diferenciam por um único par de base. Essa baixa diferenciação se manteve quando ampliamos a amostragem ao longo da distribuição dessa espécie, com amostras da Península Antartica, ilhas Marion e de sequências disponíveis no Genbank provenimentes da Austrália e Ilhas Kerguelen. Para justificar essa baixa diversidade genética levantamos duas possíveis explicações, as populações de L. dominicanus teriam passado por um severo evento demográfico ou por eventos de seleção. Para distinguir entre esses dois cenários desenvolvemos 13 marcadores nucleares não ligados, buscando encontrar um padrão caso as populações de L. dominicanus tivessem passado por eventos demográficos. Eventos demográficos marcam o genoma da espécie como um todo (DNA mitocondrial e nuclear), por outro lado eventos seletivos marcam somente o loccus sob seleção e gene ligados a estes. Dessa forma, se a redução da variabilidade genética de Larus dominicanus for resultado de eventos seletivos é esperado que marcadores DNA nuclear apresentem variação, mas não apresentem sinal de expansão populacional. Nos 13 loci nucleares analisados no presente estudo foi observado grande diversidade genética e nenhum sinal de expansão populacional. Assim, concluímos que L. dominicanus é uma espécie adaptada às novas condições ambientais criadas pelas atividades antrópicas. Essa espécie apresenta grande suceso reprodutivo e nenhum desvio da razão sexual. A baixa diversidade genética observada no DNA mitocondrial comparada com a alta variabilidade encontrada em diferente loci nucleares, parece indicar que essa espécie tenha passado por um evento de seleção na molécula mitocodrial. Do ponto de vista da conservação a alta variabilidade genética encontrada no nuclear é condizente com a ampla distribuição da espécie. Aparentemente essa espécie não demonstra ter o baixo nível de diversidade a ponto de ser preocupante para a manutenção da espécie. Por outro lado, a baixa diversidade encontrada no DNA mitocondrial abre uma importante expectativa para se compreender como a evolução tem atuado nos organismos marinhos e quais os processos que tem levado à diversificacação desse grupo.Larus dominicanus is a widely distributed species in the Southern Hemisphere, and it breeds on islands close to the continents. In the last few decades this species presented great population expansions, due to its generalist habits and its great competitive capacity. These populations expansions ended up leading to the displacement of other seabirds and marine mammals of the breeding sites. In this sense, studies that seek understanding the biology and evolution of L. dominucanus are fundamental to create management and conservation plans to the seabird assemblage on the Brazilian coast. The primary aim of this study was to characterize the reproductive biology of Larus dominicanus, in order to determine the species reproductive success. In addition we evaluated the sex ratio of the populations throughout the Brazilian coast. In order to accomplish this we studied the reproductive biology of the species in one breeding colony in São Paulo state. We observed that L. dominicanus presented high reproductive success with about 70% of the eggs hatching and 50% of the chicks surviving until the flight phase. The chicks present a fast growth and within 30 days were mature enough to fly, making them able to escape from the predators. We also observed that before the flight phase, during the egg phase and mainly the first 15 days of life, the eggs and the chicks were more susceptible to vulture attacks, the main predator of the species in São Paulo state. In this sense, with a 50% rate survival and low predation rates after the flight phase, we can infer that the populations of L. dominicanus must be going through high increments per year. The secondary sex ratio analyzed to all populations sampled through the Brazilian coast did not show deviation from the 1:1 proportion. This result indicated that the L. dominicanus populations are stable, a characteristic expected to be found in populations that breed in sites with good environmental conditions. In a case like this, the parents do not need to favor the gender that needs less energy to survive, what would lead to a deviation in the sex ratio. In this scenario of high reproductive success and equal proportion of males and females in a widely distributed species, we expected to find high levels of genetic variability both among and in the populations. Nevertheless, our mitochondrial DNA (mtDNA) data revealed an opposite situation. We studied two mitochondrial genes (cytb, ATPase 8 and 6) and observed that throughout the whole Brazilian coast the 11 genetic diversity for the group was practically null. We found only one haplotype to the cytb and two haplotypes for the ATPase 8 and 6, these last two were different for one base pair. The low differentiation was maintained when we extended the sampling to the whole species\' distribution , with samples from the Antarctic Peninsula and the Marion Islands, and sequences from the Genbank from Australia and Kerguelen Islands. We proposed two scenarios that could explain this extremely low variability, either the populations of L. dominicanus went through a severe demographic event, or through selection events. In order to distinguish among this processes, we development 13 not linked nuclear markers, searching for a common pattern between the nuclear markers and the mtDNA genes. If the L. dominicanus populations had gone through demographic events, we expected to find the same expansion signal in the nuclear markers, once demographic events would be marked in the whole genome, both nuclear and mitochondrial. On the other hand, if the low genetic variability observed resulted from selective events, we expected to find variation in the nuclear DNA, and not to find an expansion signal. Our results showed exactly the last scenario, with high genetic diversity in all 13 nuclear not linked loci and no expansion signal. Even in more detailed analyses, with a higher number of individuals, the same pattern of neutrality, and not of population expansion, for the nuclear markers was found. Therefore, we concluded that L. dominicanus is an extremely well adapted species for the new environmental conditions generated by antropic activities. The species showed great reproductive success and no deviation of the 1.1 sex ratio. The low genetic diversity observed in mitochondrial DNA compared with the high variability found in different nuclear loci, indicate that this species has gone through selective processes on the mitochondrial molecule. To the conservation point of view, the high genetic variability found in nuclear markers is in agreement with the wide distribution of the species. Apparently, this species do not present diversity levels low enough to generate worries regarding its maintenance. In addition, the low levels of diversity found on the mitochondrial DNA open new frontiers to understand how evolution has acted on marine organisms and what are the processes that lead to the diversification of this group

Evolutionary history of Kelp Gulls at the South Hemisphere

Kelp Gull is the most abundant gull species in the Southern Hemisphere, occurring in South America, Africa, New Zealand, Australia, Sub-Antarctic Island, and Antarctica Peninsula. There is no consensus about the number of subspecies; some studies proposed two and others six subspecies. Previous genetic studies with this species show low genetic diversity at mtDNA, in contrast to the high variability found in the nuclear gene. Thus, this study proposed to evaluate the subspecies of Kelp Gull through mtDNA, recovering the demographic history and population genetic structure throughout the South Hemisphere. For this, we sequenced Cytochrome b in 98 samples of Kelp Gull from Brazil, Argentina, and Antarctica, and added to the dataset 20 haplotypes available in GenBank. Bayesian Phylogeny did not support a clade in any subspecies proposed. However, it is possible to observe the genetic population structure of Kelp Gull in the Southern Hemisphere based on haplotype frequency. In addition, there is evidence that Kelp Gull lost genetic diversity, following population expansion during Holocene around 2500–3000 years ago.Fil: Linhares, Heloisa Helena. Pontifícia Universidade Católica de Minas Gerais; BrasilFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Milliones, Ana. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Pires de Mendonça Dantas, Gisele. Pontifícia Universidade Católica de Minas Gerais; Brasi

Genetic variability in mitochondrial and nuclear genes of Larus dominicanus (Charadriiformes, Laridae) from the Brazilian coast

Several phylogeographic studies of seabirds have documented low genetic diversity that has been attributed to bottleneck events or individual capacity for dispersal. Few studies have been done in seabirds on the Brazilian coast and all have shown low genetic differentiation on a wide geographic scale. The Kelp Gull is a common species with a wide distribution in the Southern Hemisphere. In this study, we used mitochondrial and nuclear markers to examine the genetic variability of Kelp Gull populations on the Brazilian coast and compared this variability with that of sub-Antarctic island populations of this species. Kelp Gulls showed extremely low genetic variability for mitochondrial markers (cytb and ATPase) and high diversity for a nuclear locus (intron 7 of the β-fibrinogen). The intraspecific evolutionary history of Kelp Gulls showed that the variability found in intron 7 of the β-fibrinogen gene was compatible with the variability expected under neutral evolution but suggested an increase in population size during the last 10,000 years. However, none of the markers revealed evidence of a bottleneck population. These findings indicate that the recent origin of Kelp Gulls is the main explanation for their nuclear diversity, although selective pressure on the mtDNA of this species cannot be discarded

DNA sampling from eggshells and microsatellite genotyping in rare tropical birds: Case study on Brazilian Merganser

This study shows that sampling maternal DNA from hatched and abandoned eggshells is a viable noninvasive strategy for studying the genetics of rare or endangered tropical birds, as exemplified here by the Brazilian Merganser (Mergus octosetaceus). Eighteen microsatellites were isolated from enriched libraries and nine heterologous loci from related species were tested. Seven loci were amplified successfully, with five of them being polymorphic. These loci exhibited amplicons ranging from 110 to 254 bp for 132 samples, with 60 from eggshells and 72 from blood or muscle samples. The number of alleles for M. octosetaceus ranged from one to six (mean = 3.71), which is low compared to M. merganser (1-15 alleles), a ‘least concern’ species. Genetic diversity did not differ significantly between noninvasive and invasive samples (Z(u) = 0.31, p = 0.37). Thus, noninvasive sampling, as demonstrated here with eggshells, provides an efficient means to assess genetic diversity in tropical birds without the need to capture and handle them

Evolutionary history of the kelp gull (Larus dominicanus) at the south hemisphere supported by multilocus evidence

The high dispersal ability of seabirds and theabsence of geographical barriers has led to high gene flowand reduced population differentiation. Nevertheless, somespecies with philopatric behavior have restricted gene flowamong colonies, revealing a strong population structure.Gulls show widespread colonial behavior, and are longlivedspecies, which make them a good model for understandingevolutionary processes in seabirds. Previousgenetic studies on the Kelp Gull (Larus dominicanus) haverevealed low genetic variability in mitochondrial markersbut relatively high genetic variation in a nuclear marker.These observations can be explained by the occurrence of aselective sweep on mtDNA, population genetic bottlenecksor a recent origin of the species. We used microsatellitedata to further investigate these hypotheses, mainly bytesting for bottleneck events. Low genetic variability(Ho = 0.276?0.570) was detected in Kelp Gulls. However,population genetic structure was observed among regions(Chile, Argentina and Brazil), and between continents(South America and Antarctica). The population of theKelp Gull in South America may have differentiated due toisolation by distance (r = 0.7273, p = 0.0013), whereasthe population in the Antarctic seems to be isolated by nonphysicalbarriers. Bottleneck events were detected in 6 outof 14 colonies studied. These colonies are at the limits ofthe distribution of the Kelp Gull, and thus experience harshsurvival conditions. We believe that the Kelp Gull has acomplex history in the southern hemisphere, with a recentorigin, followed by bottlenecks and then population expansion. Thus, the genetic diversity found in Kelp Gull issimilar to that observed for other species of Laridae.Fil: de Almeida Santos, Fernanda. Universidade de Sao Paulo; BrasilFil: Stenghel Morgante, João. Universidade de Sao Paulo; BrasilFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Millones, Ana. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Sander, Martin. Universidad de Vale do Rio dos Sinos; BrasilFil: de Abreu Vianna, Juliana. Pontificia Universidad Católica de Chile; ChileFil: Pires de Mendonça Dantas, Gisele. Universidade de Sao Paulo; Brasil. Pontificia Universidade Catolica de Minas Gerais.; Brasi

Demographic history of the Magellanic Penguin (Spheniscus magellanicus) on the Pacific and Atlantic coasts of South America

Spatial subdivision, local extinction and recolonization influence the genetic variation of natural populations. Different levels of population structure can be identified in nature, from panmictic populations, in which high gene flow homogenizes diversity across localities, to metapopulations, where combinations of moderate to high levels of population differentiation and source-sink population dynamics are expected. Gene flow, dispersal and recolonization can be affected by changes in ecological conditions such as climate and resource distribution. Evaluating demographic history is crucial for understanding current population dynamics. We assessed a mitchondrial DNA (mtDNA) control region and microsatellite data for 210 Magellanic Penguins (Spheniscus magellanicus) from 13 breeding colonies on the coastlines of Chile and Argentina, covering a great portion of the species’ distribution. We found high levels of genetic diversity and detected two genetic-geographic regions, Pacific and Atlantic, probably due to interruption of the connection between the oceans during the Last Glacial Maximum (LGM), when several parts of the Magellanic Channel were connected to the continent. The Atlantic ocean colonies showed a slight differentiation between the northern and southern colonies, and the Falkand/Malvinas one seems to be a mix of northern, southern and Pacific colonies. Magellanic Penguins showed intense gene flown among colonies, and exhibited low levels of genetic differentiation in each region. Furthermore, our findings indicate that the Magellanic Penguin experienced a population expansion around 17,500 years ago, which is in agreement with the timing of a decreased sea level and the exposure of the continental shelf along the coast of Argentina and the Falkland/Malvinas Islands at the end of the LGM. Thus, our results suggest that climate changes that affect the sea level in South America can play important roles in the migration of Magellanic Penguins.Fil: Dantas, Gisele Pires Mendonça. Pontificia Universidade Catolica de Minas Gerais; . Universidade Federal de Minas Gerais; BrasilFil: Maria, Gabriella Cardoso. Universidade de Sao Paulo; BrasilFil: Marasco, Anna Carolina Milo. Universidade de Sao Paulo; BrasilFil: Castro, Larissa Tormena. Universidade de Sao Paulo; BrasilFil: Almeida, Vanessa Simão. Universidade de Sao Paulo; BrasilFil: Santos, Fabricio Rodrigues. Universidade Federal de Minas Gerais; BrasilFil: Rosa de Oliveira, Larissa. Universidade Do Vale Do Rio Dos Sinos; BrasilFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Milliones, Anna. Universidad Nacional de la Patagonia Austral; ArgentinaFil: González Acuña, Daniel. Universidad de Concepción; ChileFil: Morgante, João Stenghel. Universidade de Sao Paulo; BrasilFil: Vianna, Juliana A.. Pontificia Universidad Católica de Chile; Chile. Universidad Católica de Chile; Chil