RESEARCH INTERESTS
As a Biological Anthropologist with research interests in primate behavior, ecology, and evolutionary biology, I believe that it is important to address research questions using an interdisciplinary and collaborative approach. In this light, I combine traditional fieldwork and laboratory techniques to answer larger evolutionary questions related to primate social and reproductive strategies.
At present, members of my lab focus on two main avenues of inquiry:
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How landscape features – past, present, and future – influence patterns of distribution, migration, and genetic diversity in wild primate populations; and
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How the resulting patterns of genetic relatedness within populations and groups can help us to explain the evolution and maintenance of complex social behaviors.
POPULATION & LANDSCAPE GENETICS
Madagascar is routinely identified as a global conservation priority because of its unique biota. Since the 1950s, more than half of Madagascar’s remaining forest cover has been cleared and forest edges have quadrupled (Harper et al. 2007). In fact, some authorities estimate as much as 85-90% of primary vegetation has already been lost (e.g., Myers et al. 2000). Land use practices including logging, mining, and slash and burn agriculture (tavy) continue to threaten Madagascar’s unique flora and fauna.
Lemurs are at particular risk. In fact, the IUCN recently named lemurs the world's most endangered mammals (IUCN 2013). Currently 93 of 103 lemur taxa (90%) are classified as at least Vulnerable and the number of species listed as Critically Endangered (i.e., at extremely high risk of extinction in the wild) has tripled since 2008 (Schwitzer et al. 2013). Understanding the genetic structure of these threatened populations, particularly those that exist in degraded or fragmented habitats, has become an urgent priority for conservation efforts (Schwartz et al. 2006; Frankham 2010).
My current projects investigate the landscape genetics of black-and-white ruffed lemurs (Varecia variegata) at local (Holmes et al. 2013), regional (Mancini & Baden, in preparation), and range-wide scales (Baden et al. 2014, Baden et al. in preparation), as well as the population genetics and underlying genetic structure of red-bellied lemurs (Eulemur rubriventer, with Stacey Tecot, Univ. Arizona & Rachel Jacobs, George Washington University) and ring-tailed lemurs (Lemur catta, with Tara Clarke, Duke & Marni La Fleur, Univ. Colorado, Boulder, in partnership with Lemur Love, LLC) across diverse habitats.
I am also one of two scientists (with Toni Lyn Morelli, UMass-Amherst) leading an international collaboration of experts from more than 15 non-profit conservation organizations, zoos, and academic institutions to integrate geospatial analysis, species distribution and occupancy modeling, and population and landscape genetics techniques to facilitate in situ ruffed lemur conservation in the face of land use and climate change.
EVOLUTION OF LEMUR SOCIAL & REPRODUCTIVE STRATEGIES
My ongoing studies of genetic structure and gene flow have allowed me to infer dispersal biases and estimate genetic relatedness among individuals within their respective social communities. This has, in turn, allowed me to use tools in molecular ecology to investigate the evolution and maintenance of complex social behaviors.
My research currently focuses on two main aspects of lemur social complexity: allomaternal care & fission-fusion social dynamics.
ALLOMATERNAL CARE
Ruffed lemur communal breeding
Communal nesting, where several mothers regularly pool and cooperatively rear offspring, is unusual in mammals, particularly primates. In previous work, I have found that communal care is facultative; not all mothers participate in communal crèches, but those that do have greater maternal success (Baden et al. 2013). My ongoing work continues to study these behaviors to address questions of how maternal energetic demands, food availability, kinship, and hormonal cues regulate and promote these behaviors in wild ruffed lemurs.
Red-bellied lemur allomaternal care
Since 2013, Stacey Tecot (Univ. Arizona) and I have been using a unique combination of molecular, endocrine, and observational methods to investigate how wild red-bellied lemur (Eulemur rubriventer) individuals are shaped into allomaternal helpers. Our research is directed at identifying 1) the pressures that select for shared infant care behaviors, 2) the mechanisms promoting and maintaining such behaviors in paternal and alloparental helpers, and 3) the adaptive benefits of allomaternal care to mothers who allow others to help.
BEHAVIORAL FLEXIBILITY & FISSION-FUSION DYNAMICS
Fission-fusion dynamics, the fluid, spatiotemporal variation in a species' group size, composition and cohesion, is a rare and unusual social strategy employed by some mammals to cope with fluctuations in resource abundance within a given habitat. Though typically only thought to occur in some anthropoids (e.g., chimpanzees and spider monkeys), this social strategy is more common among primates than originally thought (Aureli et al. 2008).
In a series of manucripts, my colleagues Drs. Tim Webster (ASU) & Jason Kamilar (UMass-Amherst), and I use social network analyses to investigate patterns of social association in ruffed lemurs (Varecia variegata), a species that exhibits a much higher degree of fission-fusion dynamics than other lemurs.
Our work has focused on characterizing ruffed lemur fission-fusion dynamics (Baden et al. 2016); quantifying social bonds via network analysis (Baden & Webster 2016, in prep); and asking whether and how associations are related to inter-individual patterns of spatial ecology and kinship (Baden et al. 2014, in prep).