Raisa Hernández-Pacheco

Negative density-dependence in female rhesus macaque fertility

contributed by Raisa Hernández-Pacheco
lab instagram: @csulb_quantecolab


Animals, Caribbean, Conservation, Demography, Density-dependence, Dynamics, Ecology, Field, Forest, Fundamental research, Hispanic, Latino/a/x, Life tables, Medicine, Observational, Population ecology, Psychology, Puerto Rican, Restoration, Terrestrial, Woman


View and download in google slides here

Note: click the gear symbol or see below for notes that accompany the presentation

Other Resources

Hernández‐Pacheco, R. et al.  2013. Demographic variability and density‐dependent dynamics of a free‐ranging rhesus macaque population. American Journal of Primatology. https://doi.org/10.1002/ajp.22177 

Hernández-Pacheco, Raisa, and Ulrich K. Steiner. 2017. Drivers of Diversification in Individual Life Courses. The American Naturalist 190(6): E132-E144.

Presentation Notes

Researcher’s Background

Raisa is a population ecologist at California State University-Long Beach, and she studies environmental factors controlling the size of animal populations

PB: Why did you become a biologist?

RHP: I am interested in understanding why individuals within a population vary and what factors support and maintain such variation. I am also fascinated with the possibility of describing how this individual-level variability translates into population dynamics through statistical models.

PB: What is your favorite part about your job?

RHP: One of the best parts of my job is the opportunity to be surrounded by smart, passionate, and talented people that I get to call peers. Some of that people can be students who share similar interests with me. The opportunity to mentor them and contribute to their careers is a great part of the job.  

PB: What obstacles have you overcome to get where you are?

RHP: Our job demands a lot of time, thus, having your goals set in your mind helps you to focus and ultimately create a good work-life balance.

PB: What advice do you have for aspiring biologists?

RHP: From a professional/training perspective, get into research as soon as you can. If you can have more than one research experience,  do so. From a personal perspective, not everyone – including family and friends – understand what an academic does for a living. Part of being successful in this career is to connect with colleagues that understand and support you on every step of your career. Fortunately, that is not difficult.

PB: Do you feel that any dimension of your identity is invisible or under-represented/marginalized in STEM?

RHP: Yes

PB: Can you elaborate on your answer above?

RHP: I do not feel invisible or marginalized. However, as a Latino woman in a highly quantitative field of biology working as a faculty member of a US institution, I am under-represented. Women in STEM are increasing in numbers but there are still many goals to reach concerning equality and equity. Latinos in STEM face even more difficult challenges, some of them related to many social aspects that create disadvantage such as being a low-income, first generation college student. My identity as a Puerto Rican is tied to both of these aspects but I am also lucky to be part of a US institution full of awareness that works towards eliminating some of these challenges.

Research Overview

Take home message of study

Density‐dependence is a major mechanism of population regulation. Even when food is not scarce, populations can exhibit density-dependent growth potentially due to social behaviors, and thus it is important to incorporate this information into demographic models for a better understanding of the mechanisms regulating the growth of primate populations.

Study system

Cayo Santiago rhesus macaque social group, Humacao, Puerto Rico. 

Key Research Points

Main figure

Density-dependent relationship between the annual proportion of nonbreeder (NB; closed circles), breeder (B; open circles), and failed breeder (crosses) females and the total number of adult macaques in the population.

Societal Relevance

Cayo Santiago is one of the oldest monkey colonies in the world. This colony provides a unique opportunity to study non-human primates in semi-natural conditions. Given their direct link to humans, research at Cayo Santiago has direct implications to human societies through non-invasive biomedical studies (e.g., autism, disease), behavioral studies (e.g., psychology), ecological studies (e.g., conservation, management), among many others. 

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