Brazilian hotspots and refugia

Brazilianforests are widely known for their high biodiversity. Two hotspots were identified in Brazil by Myers et al.(2000): the Biome of Cerrado and the Biome of Atlantic Forest. Hotspots are regions or areas with high endemism and exceptional loss of habitat, that make them priority in conservation politics.

                The Atlantic Forest has been deforested along the last 500 years. Nowadays, less than 8% of the original cover is rested. Despite its diminished state, the Atlantic Foreststill ranks as a global conservation priority. Although it is just a small fraction of the size of the huge Amazon rainforest, the Atlantic Forest still harbors of a range of biological diversity similar to that of the Amazon. Not only similar in richness, but following Costa (2003), both forests were connected during the Pleistocene, and the Atlantic and Amazon’s fauna are relative.

We have seen that the Late Quaternary climate fluctuations helped to shape present-day diversity, providing a general context for understanding current patterns of endemism. Carnaval et al. (2009) related refuge areas and biodiversity in Brazilian Atlantic forest hotspot. In the study, the authors used frogs as indicators; ecological niche models under paleoclimates; and simultaneous Bayesian analyses of multispecies molecular data to compare alternative hypotheses of assemblage-scale response to late Quaternary climate change.

In a regional scale, biodiversity species should consistently show higher genetic diversity within and among populations in refugia relative to recent colonized areas. This is explained by the long-term persistence and population structure. The genetic signature of population expansion in unstable (recent colonized) areas, should reflect multispecies colonization from adjacent refugial regions after the Last Glacial Maximum (Carnaval et al. 2009).

Besides, the absence of genetic patterns of isolation-by-distance in recent colonized areas is due to colonization has been too recent to permit restoration of equilibrium between migration and genetic drift.

Following all predicts, the authors supposed a large central refugium throughout the Late Quarternary – Bahia refugium; a second much smaller in the northeastern most of forest – Pernambuco refugium; and a southeastern refugium of intermediate size – São Paulorefugium. The authors also supposed that these areas received a significant influx of migrants from adjacent, large refugial populations after Late Quaternary Maximum. The southern Atlantic forest was climatically unstable relative to the central part (Bahia).

I am from Espírito Santo, a state between São Paulo and Bahia and, following the article, it is included in Bahiarefugium. During my on field works, I could realize the difference among the forests. The Bahia Atlantic Forest (northern of my state) is drier and the fauna, generally, is less related to animals from the southernmost (more humid and high altitude). Otherwise, São Paulo has humid and high altitude forests, as the southern of my state.

Finally, this paper was quite interesting for my, because actually, the highest diversity that we have been found for a wasp family (Bethylidae) in Brazil occurs in the central part of the Atlantic Forest, which the authors called Bahia refugium. 

 

 

 

Carnaval AC et al. 2009. Stability Predicts Genetic Diversity in the Brazilian Atlantic ForestHotspot.

Costa LP. 2003. The historical brigde between the Amazon Forest of Brazil: a study of molecular phylogeography with small mammals. Journal of Biogeography 30: 71-86.

Myers N, Mittermeier RA, Mittermeier CG, da Fonseca GAB, Kent J. 2000. Biodiversity hotspots for conservation priorities. Nature 403: 853-858.

Science 323: 785-789.

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