Island Rule, quantitative genetics and brain–body size evolution in Homo floresiensis
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2017-06
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Resumo
Colonization of islands often activate a complex chain of adaptive events
that, over a relatively short evolutionary time, may drive strong shifts in
body size, a pattern known as the Island Rule. It is arguably difficult to perform
a direct analysis of the natural selection forces behind such a change in
body size. Here, we used quantitative evolutionary genetic models, coupled
with simulations and pattern-oriented modelling, to analyse the evolution of
brain and body size in Homo floresiensis, a diminutive hominin species
that appeared around 700 kya and survived up to relatively recent times
(60–90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution
was rejected in 97% of the simulations, and estimated selection gradients are
within the range found in living natural populations. We showed that insularity
may have triggered slightly different evolutionary trajectories for body
and brain size, which means explaining the exceedingly small cranial
volume of H. floresiensis requires additional selective forces acting on brain
size alone. Our analyses also support previous conclusions that H. floresiensis
may be most likely derived from an early Indonesian H. erectus, which
is coherent with currently accepted biogeographical scenario for Homo
expansion out of Africa.
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Adaptive evolution, Island rule, Brain–body size correlation, Homo floresiensis, Dwarfing, Evolutionary genetics
Citação
DINIZ-FILHO, José Alexandre Felizola; RAIA, Pasquale. Island rule, quantitative genetics and brain-body size evolution in. Proceedings. Biological sciences, London, v. 284, n. 1857, e20171065, June 2017.