Island Rule, quantitative genetics and brain–body size evolution in Homo floresiensis

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 cha...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2017-06, Vol.284 (1857), p.20171065-20171065
Main Authors: Diniz-Filho, José Alexandre Felizola, Raia, Pasquale
Format: Article
Language:English
Subjects:
Adaptive Evolution
Animal behavior
Animals
Biological Evolution
Body Size
Brain
Brain - anatomy & histology
Brain–body Size Correlation
Colonization
Computer simulation
Dwarfing
Ecology
Evolution
Evolutionary Genetics
Fossils
Genetics
Hominidae
Hominids
Homo floresiensis
Indonesia
Island Rule
Islands
Natural populations
Natural selection
Organ Size
Quantitative genetics
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Summary: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.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.2017.1065