Diversity and genetic connectivity among populations of a threatened tree (<Emphasis Type="Italic">Dalbergia nigra</Emphasis>) in a recently fragmented landscape of the Brazilian Atlantic Forest |
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Authors: | Luciana?Cunha?Resende Renata?Acácio?Ribeiro Email author" target="_blank">Maria?Bernadete?LovatoEmail author |
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Institution: | 1.Departamento de Biologia Geral, Instituto de Ciências Biológicas,Universidade Federal de Minas Gerais,Belo Horizonte,Brazil;2.Departamento de Ciências Biológicas, Faculdade de Ciências Biológicas e da Saúde,Universidade Federal dos Vales do Jequitinhonha e Mucuri,Diamantina,Brazil |
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Abstract: | In this study we evaluated the influence of recent landscape fragmentation on the dynamics of remnant fragments from the Brazilian
Atlantic Forest. This biome is one of the richest in the world and has been extensively deforested and fragmented. We sampled
five populations of the threatened Dalbergia nigra, a tree endemic to the Brazilian Atlantic Forest, two located in a large reserve of continuous forest and three in fragments
of different sizes and levels of disturbance. In order to assess historical changes, considering the longevity of the analyzed
species, 119 adults and 116 saplings were genotyped for six microsatellite loci. Lower levels of genetic diversity were found
in the most impacted fragments when compared to the most preserved population located inside the reserve, and there was significant
genetic structure among the populations studied (pairwise F
ST = 0.031–0.152; pairwise D
EST = 0.039–0.301). However, genetic structure among saplings (F
ST = 0.056; D
EST = 0.231) was significantly lower than among adults (F
ST = 0.088; D
EST = 0.275). Estimates of contemporary gene flow based on assignment tests corroborated this result, suggesting that fragmentation
led to an increase in gene flow. This connectivity among remnant fragments could mitigate the loss of genetic diversity through
a metapopulation dynamic, but the high rate of habitat loss and the unknown long-term genetic effects add uncertainty. These
results, taken together with the presence of private alleles in disturbed populations, highlight the importance of preserving
the extant fragments. |
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