Leslie J. Digby
  • Leslie J. Digby

  • Associate Professor of the Practice and DUS
  • Evolutionary Anthropology
  • 08A Bio Sci Building
  • Campus Box 90383
  • Phone: (919) 660-7398
  • Fax: (919) 660-7348
  • Office Hours: MW 9:30-11am and by appointment
  • Curriculum Vitae
  • Specialties

    • Primate Ecology
    • Behavioral Ecology and Physiology
  • Research Summary

    Evolution of Primate and Human Social Behavior; Primate Behavioral Ecology; Mating Systems and Infanticide; Behavioral Thermoregulation; Three-dimensional home-range use; Lemurs, Marmosets
  • Research Description

    My research has centered on the evolution primate social and reproductive behavior (including female-female competition) for many years. Working with marmosets and lemurs, I've investigated the evolution of infanticide, mating systems and cooperative breeding. In the last few years I've also begun to study more ecological aspects of behavior, in particular the methods and impact of habitat use by lemurs. One of the themes of this research is the three-dimensional use of space by arboreal primates. Using the natural habitat enclosures of the Duke Lemur Center, we've been able to track (using GPS) the animals and determine a home-range 'volume' that provides a much richer look at habitat use than the traditional two-dimensional home-range areas. We are also working on determining the factors that contribute to the use of different locations and heights within the forest. Using thermography, IR thermometers, and ibuttons that track temperature and humidity, we're investigating how surface and ambient temperatures impact the lemurs' use of their forest habitats. Understanding this type of behavioral thermoregulation and use of microhabitats could have far reaching implications for why animals are restricted to certain types of forest, geographic locations and even how species respond to long-term climate variation.
  • Current Projects

    Methods for Mapping Primate Home Ranges, Behavioral thermoregulation in primates, Comparative Cognition in Lemurs
  • Areas of Interest

    Primate Behavioral Ecology
    Home-range
    behavioral thermoregulation
    Mammalian Mating Systems
    Methods in Behavioral Ecology
    Marmosets and Tamarins
    Lemurs
  • Education

      • PhD,
      • Anthropology,
      • University of California, Davis,
      • 1994
      • M.A.,
      • Anthropology,
      • University of California, Davis,
      • 1988
      • BA,
      • Biology,
      • University of California, San Diego,
      • 1986
  • Selected Publications

      • Saltzman, W, Digby, L.J. and Abbott, D.H..
      • 2009.
      • Reproductive skew in female common marmosets: what can proximate mechanisms tell us about ultimate causes?.
      • Proceedings of the Royal Society B
      • .
      Publication Description

      Common marmosets are cooperatively breeding monkeys that exhibit high reproductive skew: most subordinate females fail to reproduce, while others attempt to breed but produce very few surviving infants. An extensive dataset on the mechanisms limiting reproduction in laboratory-housed and freeliving subordinate females provides unique insights into the causes of reproductive skew. Non-breeding adult females undergo suppression of ovulation and inhibition of sexual behaviour; however, they receive little or no aggression or mating interference by dominants and do not exhibit behavioural or physiological signs of stress. Breeding subordinate females receive comparable amounts of aggression no non-breeding females but are able to conceive, gestate and lactate normally. In groups containing two breeding females, however, both dominant and subordinate breeders kill one another’s infants. These findings suggest that preconception reproductive suppression is not imposed on subordinate females by dominants, at a proximate level, but is instead self-imposed by most subordinates, consistent with restraint models of reproductive skew. In contrast to restraint models, however, this self-suppression probably evolved not in response to the threat of eviction by dominant females but in response to the threat of infanticide. Thus, reproductive skew in this species appears to be generated predominantly by subordinate self-restraint, in a proximate sense, but ultimately by dominant control over subordinates’ reproductive attempts.

      • L.J. Digby, S.F. Ferrari, W. Saltzman.
      • 2006.
      • Callitrichines: the role of competition in cooperatively breeding species..
      • .
      • L. Digby and W. Saltzman.
      • 2009.
      • Balancing cooperation and competition in callitrichid primates: examining the relative risk of infanticide across species.
      • .
      Publication Description

      At least seven cases of infanticide by females other than the mother have been observed in wild groups of common marmosets (Callithrix jacchus), with several more cases described for captive groups. Infanticide by females other than the mother has not, however, been documented for wild groups of other callitrichine species. Why might such overt aggression toward infants occur in one species and not others? In the common marmoset, a variety of social, reproductive and ecological characteristics – including short inter- birth intervals (and the resulting potential for overlapping of pregnancies and births), habitat saturation, small home ranges, and low cost of infant care (including decreased travel costs and short dependency periods compared to other callitrichines) – may contribute to an increased likelihood of two breeding females being present in a group, which in turn gives rise to the potential for competition between breeding females and ultimately to infanticide. These conditions are less common in wild groups of most other callitrichines species. All callitrichines balance the need for cooperative care of young with the reproductive competition that results from limited reproductive opportunities; however ecological and social conditions appear to tip the balance toward infanticide more frequently in common marmosets than in other callitrichine species.

      • Abbott, D.H., Digby, L.J. and Saltzman, W..
      • 2009.
      • Reproductive skew in female common marmosets: contributions of infanticide and subordinate self restraint..
      • .
      • L.J. Digby, A. Stevens.
      • 2007.
      • Maintance of Female Dominance in Blue-Eyed Black Lemurs (Eulemur macaco flavifrons) and Gray Bamboo Lemurs (Hapalemur griseus) under semi-free ranging and captive conditions.
      • Zoo Biology
      • 26:
      • 345-361
      • .
      • L.J. Digby.
      • 2000.
      • Infanticide by female mammals: implications for the evolution of social systems.
      • 423-446
      • .
      • L.J. Digby, S. Kahlenberg.
      • 2002.
      • Female dominance in blue-eyed black lemurs (Eulemur macaco flavifrons.
      • Primates
      • 43:
      • 191-200
      • .
      • L.J. Digby.
      • 1995.
      • Infant care, infanticide, and female reproductive strategies in polygynous groups of common marmosets (Callithrix jacchus).
      • Behavioral Ecology and Sociobiology
      • 37:
      • 51-61
      • .
      • Digby, L.J. and S.F. Ferrari.
      • 1994.
      • Multiple breeding females in free-ranging groups of Callithrix jacchus.
      • . International Journal of Primatology
      • 15:
      • 389-397
      • .
      • C. Nievergelt, L.J. Digby, U. Ramakrishnan, and D.S. Woodruff.
      • 2000.
      • Genetic analysis of group composition and breeding system in a wild common marmoset (Callithrix jacchus) population.
      • International Journal of Primatology
      • 21:
      • 1-20
      • .
      • L.J. Digby.
      • 1999.
      • Sexual behavior and extra-group copulations in a wild population of common marmosets (Callithrix jacchus).
      • Folia Primatologica
      • 70:
      • 136-145
      • .
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  • Teaching

    • EVANTH 344L.01
      • PRIMATE FIELD BIOLOGY
      • Lemur CTR
      • TuTh 08:30 AM-09:45 AM
    • EVANTH 495S.01
      • ADV RESEARCH EVOL/ANTHOPOLOGY
      • Bio Sci 063
      • W 04:40 PM-05:55 PM