Friday, September 5, 2014

Phylogeographic endemism

Phylogeographic endemism is the measure of the degree to which the history of recently evolved lineages is spatially restricted. To understand how the repeated climatic shifts over the last 120,000 years may have influenced today's patterns of genetic diversity, a team of researchers developed this new biodiversity metric. They believe that it reflects fundamental evolutionary processes such as cryptic divergence, adaptation and biological responses to environmental heterogeneity.

Researchers from institutions in Brazil, Australia and the United States, analyzed the effects of current and past climatic variation on the genetic diversity of 25 vertebrate species (frogs, reptiles and birds) in the highly diverse yet much threatened Brazilian Atlantic rainforest.

They discovered that the climatic regimes of the northern and southern portions of the Atlantic forest are strikingly different. While past climate dynamics predicted phylogeographic endemism in the northern forests, contemporary climatic heterogeneity explains endemism in the south. 

These results accord with recent speleothem and fossil pollen studies, suggesting that climatic variability through the last 250 kyr impacted the northern and the southern forests differently. Incorporating sub-regional differences in climate dynamics will enhance our ability to understand those processes shaping high phylogeographic and species endemism, in the Neotropics and beyond.

The authors think that studying these forest domains in isolation by using their new concept helped them to identify areas holding most unique and small-ranged genetic variation. They expect that more nuanced climatic analyses of other large complex biomes (e.g. sub-Saharan Africa, Amazonia and Neotropical savannahs) will help advance biodiversity prediction and conservation in tropical hotspots worldwide.

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