Project

Morphological Disparity & Great Apes

Goal: Testing Morphological disparity, environment and great ape skull form using morphometrics

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Alannah Pearson
added a research item
Cranial variation is known to be a mix of taxonomic, structural, and functional components, but our understanding of the evolutionary factors contributing to specific aspects of this diversity are not well known. To what extent is the amount of variation within great apes linked to the heterogeneity of the environments they inhabit? Most hominid species are allopatric suggesting that speciation and diversity are strongly linked to geographic range. Cranial morphology is strongly distinct between the species, with more subtle differences found among subspecies. We compared cranial disparity within and between these groups to the variation in several factors: geographic range size, variation of climatic variables within their ranges, variety of habitat within their ranges, and diversity of diets. A sample (n = 45) of Computed Tomography (CT) scans of museum specimens with preserved locality information from Pan paniscus (n = 9), Pan troglodytes troglodytes (n = 10), Pan troglodytes schweinfurthii (n = 17), and Pan troglodytes verus (n = 9) were generated into three- dimensional (3D) virtual crania. A total of 45 3D coordinates were virtually registered on the ectocranial surface to capture cranial form and analysed with standard geometric morphometric methods to compare size and shape. Cranial variation was analysed by first calculating morphological disparity as a numeric value estimating cranial size and shape variation for each taxon. Similar values were calculated summarising dietary and environmental variation specific to each taxon. Lastly, an evaluation of the correlation between morphological disparity, geographic range size, dietary and environmental variation was conducted for the genus Pan. The close association between geographic range, environmental variation and dietary breadth are important to understand how past environmental fluctuations might have affected primates and suggest which taxa might be more affected by such specific changes. Expansion to include more taxonomic variation, dietary breadth, range size and environmental conditions is appropriate.
Alannah Pearson
added a project goal
Testing Morphological disparity, environment and great ape skull form using morphometrics