COS 159-3 - The role of life history traits in population dynamics in a changing environment

Wednesday, August 17, 2022

10:30 AM – 10:45 AM EDT

Presenting Author(s)

MD

Michelle DePrenger-Levin

Research Associate
Denver Botanic Gardens
Denver, Colorado, United States

Slides (PDF)

Coauthor(s)

MW

Michael Wunder, PhD

Associate Professor
Department of Integrative Biology, University of Colorado Denver
Denver, Colorado, United States

Background/Question/Methods

Understanding which life history traits put a species at comparatively greater risk of extinction from demographic and environmental processes would improve conservation planning for understudied species. Extinction risk from demographic stochasticity is expected to increase with increased fecundity and decrease with higher age of maturation in finite populations. Environmental stochasticity increases risk by introducing variation in the demographic parameters that have the largest impact on population dynamics which can cause variation in (st)age structure and fluctuations in population size. Near-term population dynamics can deviate from the predicted asymptotic behavior. We used simulations of finite populations with stable growth rates to examine how demographic variation, environmental variation, and the interaction between the two impact near-term extinction risk across biological life history traits.

Results/Conclusions

For semelparous life histories, as demographic stochasticity increases and population size decreases, extinction risk increases with fecundity as predicted while at low levels of demographic stochasticity and within larger populations, the probability of extinction decreases as fecundity increases. Extinction risk for iteroparous life histories varies little as the amount of demographic variation changes. For iteroparous life histories, extinction risk decreases as age of maturation and fecundity increases. Extinction risk increases with increasing environmental stochasticity at lower ages of maturity. Environmental stochasticity is associated with a decrease in extinction risk with age of maturity and increasing fecundity for iteroparous life histories where fecundity matches age. Extinction risk for semelparous life histories increases with increasing fecundity in smaller populations. As stochasticity in both processes increase, extinction risk decreases as fecundity and age increase. In near-term projections within finite populations, environmental stochasticity drives different responses by life history traits than what would be expected from demographic stochasticity alone. Simple demographic parameters that describe a species’ life history and an understanding of which biological traits increase extinction risk can be used to improve conservation planning and direct data collection needed to select effective management actions to conserve finite populations in a changing environment.