In the broadest sense, I’m an organismal biologist trying to understand the processes responsible for generating and maintaining the remarkable biological, morphological, ecological, genetic, and behavioral diversity we observe today.  With my background in biological anthropology, I’m primarily interested in understanding these processes in human and nonhuman primates, though I also use a number of reptiles as models for evolutionary genomics. I am particularly motivated to use computational methods to explore complex, emergent phenomena, and in doing so, I study processes at multiple levels: within organisms, among organisms within populations and species, and among populations and species over time. I am thus interested in a wide range of theoretical, empirical, and methodological questions, and utilize a variety of methods and data types. Below I highlight some of my ongoing research projects and collaborators.

Genomics of Speciation and Adaptation

The Macaque Adaptive Radiation

The genus Macaca is a monophyletic clade of Old World monkeys that originated in Africa 7-8 million years ago.  In the last 5 million years, this genus has radiated into at least 23 extant species, ranging across Northern Africa, most of southern Asia, and many Pacific Islands.  This radiation is remarkable not only from the standpoint of pace – it is one of the most explosive recent primate radiations – but also because the macaques now have the largest geographic and ecological distribution among extant nonhuman primates. With my dissertation, I began and am now continuing a long-term effort to elucidate and understand the genomic landscape of divergence across this radiation.

Brenda Bradley (George Washington University)

Desert Tortoise Speciation

The southwestern United States is home to two species of desert tortoises: Gopherus agassizii (Mojave desert tortoise) and G. morafkai (Sonoran desert tortoise).  These species are of particular interest because of the endangered status of G. agassizzi and the potential role of the Colorado River and Grand Canyon in driving speciation.  However, range overlap in northwestern Arizona and strong differentiation in key ecological preferences suggests that local adaptation, rather than simple vicariance, might have been central to the divergence of these two lineages.  We are undertaking an integrative study of speciation, adaptation, and introgression in these species to better understand macroevolutionary processes in this clade.

Greer Dolby (Arizona State University)
Dale DeNardo (Arizona State University)
Kenro Kusumi (Arizona State University)
Melissa Wilson Sayres (Arizona State University)

Sex-Biased Demography

Sex-biased evolutionary processes have played a major role in shaping the evolutionary history of many species.  As the genome carries many signals of selection and demography, these processes are readily detectable using genomic data.  However, natural selection and demography can often leave similar signals in any one region of the genome, complicating the reconstruction of population history.  I am developing a theoretical and methodological framework to distinguish these evolutionary forces in genomic data, and working to reconstruct sex-biased processes in human and nonhuman primates.

Melissa Wilson Sayres (Arizona State University)

Population genomics of wild primates

Despite an enormous number of active research projects studying wild primates, very few studies have undertaken genomic investigations in these populations.  Two main obstacles to this work are (1) difficulties in noninvasive sampling DNA of a quality sufficient for next-generation sequencing and (2) a lack of methods for affordably generative and assembling population-scale data suitable for evolutionary genomic analyses in nonmodel primates.  I am working with collaborators on multiple projects aimed at solving both of these problems.  Currently we are studying populations of chimpanzees at Gombe Stream National Park in Tanzania and Verreaux’s sifaka at Beza Mahafaly in Madagascar, but I will soon be expanding into additional populations and species as well.

Brenda Bradley (George Washington University)
Ian Gilby (Arizona State University)
Richard Lawler (James Madison University)
Andrew Ozga (Arizona State University)
Anne Stone (Arizona State University)
Melissa Wilson Sayres (Arizona State University)

Cancer genomics

Cancers exhibit substantial heterogenity both within and across tumors.  A characterization of this variation is central to understanding cancer progression and developing therapies.  I apply population and evolutionary genomics methods to cancer samples to explore genomics and spatial heterogeneity within the body.

Michael Barrett (Mayo Clinic)
Melissa Wilson Sayres (Arizona State University)

Squamate evolutionary genomics

The nearly 10,000 currently recognized extant species of squamate reptiles (lizards, snakes, and relatives) comprise more than 90% of living reptiles and exhibit remarkable diversity in morphology, ecology, life history, physiology, reproductive biology, and behavior.  Surprisingly, squamates have been comparatively understudied from a genomic perspective up until this point.  I am thus very interested in using genomics to better understand this radiation.

Dale DeNardo (Arizona State University)
Shawn Rupp (Arizona State University)
Melissa Wilson Sayres (Arizona State University)

Social structure in fission-fusion societies

Fission-fusion societies exhibit fluid spatiotemporal variation in subgroup size and composition, likely as a response to fluctuations in resource availability within their habitat.  While fission-fusion dynamics have been observed in a number of primate species, very few exhibit very high degrees of fluidity.  I work to understand what features of primate behavior – cohesion, kinship, home range overlap, resource availability, social preferences, etc. – contribute to social structure in fission-fusion societies. I am particularly interested in how patterns of dyadic association and interaction can result in differences in social structure, and what consequences this has for group living.  I have worked on this question in multiple fission-fusion species (e.g., chimpanzees, spider monkeys, and ruffed lemurs), but my current work is part of a long-term collaboration with Andrea Baden at Hunter College to elucidate, in detail, patterns of fission-fusion dynamics, social association, and social structure in wild black-and-white ruffed lemurs.

Andrea Baden (Hunter College)
Jason Kamilar (UMass Amherst)
Scott Suarez (San Diego Mesa College)
David Watts (Yale University)

Previous Research

I spent much of my undergraduate and early graduate career studying primate behavioral ecology.  I conducted fieldwork studying chimpanzees in western Uganda at the Toro-Semliki Wildlife Reserve and Ngogo in Kibale National Park (collaborators included Phineas Hodson, Kevin Hunt, Linda Marchant, Bill McGrew, Charlotte Payne, and David Watts).  I also worked on projects related to behavioral genetics and primate coloration (collaborators included Stephanie Anestis, Brenda Bradley, James Higham, Jason Kamilar, and Sandra Winters).  Most of this work has been published, and you can find more information on my publications page.






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