On-Going Studies

An experimental study of male and female contributions to territoriality, parental care, and pair bond maintenance.

PI: Fernandez-Duque

Funding Agency: National Science Foundation

Dates: 2007-2010

This is an NSF-sponsored project that will examine some of the factors that may maintain social monogamy in the owl monkey population in tGuaycolec, Formosa. Three non-exclusive hypotheses to explain the maintenance of social monogamy will be examined. To test the hypothesis that females are a dispersed resource that males cannot monitor effectively, the researchers will evaluate the quality of territories as indicated by food resources and infant production and the use females make of the available food resources. The second hypothesis, which states that social monogamy arises when female reproductive costs are lessened by male care/services will be examined by studying the potential impact of infant carrying on males´ body mass, the effects of the removal of male care in the female´s reproduction, and sex differences in predator avoidance responses. Finally, to test the hypothesis that social monogamy results when males guard individual females and females compete over preferred males, this study will evaluate responses of males and females to potential intruders and the existence of female reproductive synchronicity.

Data to be collected include: 1- abundance and distribution of food resources in four territories, 2- demographic data from 41 study groups and from 15 groups in a control population, 3- morphometric data from 60 individuals to be captured, physically examined, and marked, and 4- behavioral data from ten social groups during playback experiments conducted to quantify the responses of residents to potential intruders, and during predation experiments conducted to compare antipredator responses of males and females.

This project will undoubtedly make a substantial intellectual contribution to the understanding of how primate social systems are shaped by ecological conditions. This study, developed within the framework of socioecological theory, will allow to examine the linkage between behavioral and morphological dimorphism, and between sexual dimorphism and mating systems. The study will also provide invaluable data for an on-going collaboration that examines the behavioral and ecological strategies of four different species of monogamous primates living in the Argentinean Chaco and the Ecuadorian Amazon. Finally, the long-term demographic data on owl monkeys will be useful in informing management decisions for other less well-known primate and mammal species. The owl monkeys of Argentina may be the only strictly monogamous primate species for which there will be enough information to do a population viability analysis that could be used to model the viability of other more endangered primate species.

A national program for the conservation of owl monkeys and gallery forests in the Argentinean Gran Chaco

PI: Fernandez-Duque (in collaboration with Fundación ECO, Argentinean National Parks Systems and Argentinean Wildlife Service)

Funding Agency: Conservation Trust of the National Geographic Society

Dates: 2007-2008

Owl monkeys and the gallery forests they inhabit in the South American Chaco are in need of protection as indicated by a recent evaluation conducted by a consortium of international and national organizations. Our goal is to evaluate the population status of owl monkeys in those few locations where gallery forests are protected, to identify other suitable areas for their protection, and to delineate a national plan for the conservation of owl monkeys and gallery forests. Building on the knowledge acquired during a 10-year study of an owl monkey population in a private cattle ranch, a team of young Argentinean biologists, national and provincial park rangers will: 1- evaluate owl monkey populations and their habitat in two Argentinean National Parks, one Biosphere Reserve and major rivers in Chaco Province, 2- quantify basic demographic parameters of those populations for comparison with the population studied since 1996, and 3- establish a National Plan for the Conservation of Owl Monkeys that contemplates reintroduction of the species in Chaco National Park where it went extinct several decades ago. The project will be a unique initiative in the area, bringing together managers from national and provincial offices with scientists from local NGOs and universities. The long-term conservation consequences of the project are numerous. The project will advance the career of young Argentinean biologists, strength the bonds between a local NGOs and national authorities and potentiate the benefits of an on-going local conservation education program.

Biparental Care and Social Monogamy in Primates: Behavioral and Hormonal Correlates. PI: Claudia R. Valeggia (in collaboration with E. Fernandez-Duque and A. Di Fiore)

Funding Agency: University Research Foundation

Dates: 2007-2008

Why do some male monkeys mate in a monogamous relationship presumably foregoing other reproductive opportunities? Why do they invest so heavily in the care of offspring they are not certain to have sired? The evolution and maintenance of monogamy in Neotropical primates that show intensive paternal care remains an enigma. This study is part of a long-term project that examines social monogamy in four Neotropical primates. During one year, we will study male-female social relationships and patterns of infant care in titi monkeys (Callicebus discolor) and sakis (Pithecia aequatorialis) in Ecuador and owl monkeys (Aotus azarai) in Argentina to evaluate the hypothesis that the care and services provided by males are important in the maintenance of monogamy. Using fecal samples, we will also evaluate male and female reproductive hormonal profiles to test the following: i) the extent to which males are precluded from polygyny because of female reproductive synchrony, ii) differences in testosterone profiles that may be related to parental behavior, and iii) the possible trade-off between parental care and territoriality as reflected in testosterone levels. These data will allow the first tests ever on the possible hormonal mechanisms regulating monogamy in these species.

Paternity Analyses and Population Structure of a Monogamous Primate Species

PI: Fernandez-Duque (in collaboration with T. Schurr and P. Babb)

Funding Agency: University Research Foundation

Dates: 2007-2008

Taking advantage of the DNA samples collected from 130 individuals during 2000-2005 this study will begin to examine the genetic structure of the owl monkey population in Formosa.

The proposed research will contribute to our understanding of the evolution and maintenance of monogamous social systems in primates. What is the biological relatedness of individuals in “family” groups of monogamous primates? How closely related are individuals in the various groups that make up a population? What are the consequences, in terms of reproductive success, of copulations outside the pair? Building on a 10-year long study of owl monkeys in the Argentinean Chaco, we will combine long-term behavioral and demographic data with molecular genetic data to examine the genetic structure of the population, as well as the evolution and functioning of socially monogamous groups. We will characterize maternal genetic variation, analyze the kinship structure of groups, assess paternity, and examine the possible effects of kin selection in the maintenance of social monogamy. This preliminary work will allow us to establish a very valuable primate genetic resource at Penn and to lay the groundwork for conducting a thorough analysis of the relationships between behavior, demography, and genetics. Once our long-term project has been developed, the unique combination of demographic, behavioral, and genetic data will allow us to test in a unique and robust manner some long-held assumptions derived from traditional sexual selection theory.

Comparative Socioecology of Monogamous Primates in Argentina and Ecuador.

PIs: A. Di Fiore and E. Fernandez-Duque

Funding Agencies: Leakey Foundation, Wenner-Gren Foundation.

Dates: 2003- present

Population Biology of Red Howlers (Alouatta seniculus) in Venezuela. In collaboration with Dr. Rudy Rudran, National Zoological Park, USA.

PI: R. Rudran (in collaboration with E. Fernandez-Duque

Dates: