Cal Lutheran gets its largest NSF grant

$307,486 funds biologist’s Amazonian monkey study

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During the 22 years in which Anita Stone (center) has been studying the species in her native Brazil, the last five with Cal Lutheran students, she has noticed the fattening of males’ upper bodies before and during mating season. 

(THOUSAND OAKS, Calif. — March 24, 2022) California Lutheran University received its largest National Science Foundation grant to date — $307,486 for a biologist and her students to study sexual selection in tiny Brazilian squirrel monkeys.

Assistant professor Anita Stone, the lead principal investigator, and 12 undergraduate students will spend four summers studying sexually selected traits and behaviors in the Saimiri collinsi species living in the eastern Amazonia forest. The Thousand Oaks resident wants to determine whether the females actively choose their mates, or passively accept the winners of male-male competitions.

During the 22 years in which Stone has been studying this female-dominant species in her native Brazil, the last five with Cal Lutheran students, she has noticed the fattening of males’ upper bodies before and during the mating season. She wants to find out whether the individual differences in fattening reflect male genetic quality and affect reproductive success due to females chosing mating partners based on the males’ degree of fatness.

When it comes to sexual selection based on differences in traits, the focus is typically on male-male competition rather than female choice, relegating females to a passive role in the reproductive process. This study challenges that bias.

Each summer, Stone and her students will identify and collect measurements from the monkeys, observe their behavior during the eight-week breeding season and analyze the data. The monkeys are difficult to study because they weigh no more than 2 pounds, move quickly and hang out in social groups of about 50. The researchers will employ Brazilian field assistants, take local children and teachers on field trips into the forest and present the research to residents to promote conservation in the area.

Back at UCLA, biological anthropologist Jessica Lynch will conduct paternity tests on biological samples from the baby monkeys that are born. At the University of Texas at Arlington, evolutionary biologist Janet Buckner and her graduate students will study genetic differences in blood and tissue samples to determine whether male-fattening is a product of female choice or male-male competition.

This comprehensive approach is novel because primate studies have yet to examine the links among male genetic quality, secondary sexual traits that advertise genetic quality and female choice, as has been done in other vertebrates such as birds and fish. 

The grant (NSF award number 2140666) not only funds rare opportunities for undergraduate students to study primates in the wild, but also supports the participation of women and other underrepresented groups in science. Cal Lutheran and UT Arlington are both designated Hispanic-Serving Institutions by the U.S. Department of Education.