"Developmental shift or postnatal plasticity? Manual and pedal variation in two populations of Microcebus griseorufus at Bezà Mahafaly"

Developmental shift or postnatal plasticity? Manual and pedal variation in two populations of Microcebus griseorufus at Bezà Mahafaly”

Gina Agostini
UMass Amherst
Wed, 11/18/2015 - 4:00pm

221 Integrated Sciences Building

Abstract: Under the “Narrow Niche Hypothesis” (NNH), long posterior digits are adaptive in arboreal environments to facilitate grasping thin, unstable branches.Microcebus griseorufus is a small primate residing primarily in xeric forests in southern Madagascar. We compare neighboring M. griseorufus populations to investigate whether autopod proportions conform to NNH expectations. One population resides in a gallery forest containing numerous wide-canopied trees, small branches and abundant foliage, the other population in a spiny forest with more vertically-oriented succulents, large supports and less ground cover. Previous research indicates these populations are phenotypically diverse but genetically similar. All data were collected by Dr. Emilienne Rasoazanabary. Results show that digit proportions conform to the expectations of the Narrow Niche Hypothesis. Specifically, individuals from the gallery forest possess dis-proportionally long posterior digits and a shorter pollex/hallux, while individuals from the spiny forest possess shorter posterior digits and a longer pollex/hallux. This pattern was present for both hands and feet in both sexes and in juveniles. Furthermore, results of a Qst analysis indicate divergence between these two subpopulations despite contrary evidence in mitochondrial DNA analyses. We present two proximate pathways by which these contrasting patterns could arise: [1] postnatal plasticity stimulated by differing locomotor strategies and [2] developmental shifts regulated by currently unknown genetic or epigenetic factors. The strengths and weaknesses of both will be presented.

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Refreshments at 3:45pm