[Enviro-lunch] Envirolunch Seminar for November 21st, 2022 =?utf-8?Q?=E2=80=9COn_?=the Dynamics of Mortality and the Ephemeral Nature of Megafauna”

[Justin Yeakel]

Hello everyone,

Due to a last-minute cancellation, we will be changing the lineup for our seminar on Monday, November 21st. To avoid having too many gaps in our ESS-190 course, and in lieu of our planned speaker, I’ll be giving a substitute talk (see below). You are welcome to join as part of the EnviroLunch series, despite it being an unofficial and last-minute entry!

On the Dynamics of Mortality and the Ephemeral Nature of Mammalian Megafauna

Justin Yeakel, Life & Environmental Sciences @ UC Merced

November 21st, 2022
12:00-1:15pm PST
via
https://ucmerced.zoom.us/j/85854124987

Abstract: The vital rates constraining energy flow through consumer-resource interactions largely vary as a function of body size. These allometric relationships govern the dynamics of populations, and the energetic constraints induced by different sources of mortality influence small- to large-bodied species in different ways. Here we derive the timescales associated with four alternative sources of mortality for terrestrial mammals: starvation from resource limitation, mortality associated with aging, consumption by specialist to generalist predators, and mortality introduced by subsidized harvest. The incorporation of these allometric relationships into a minimal consumer-resource dynamic system illuminates central constraints that may contribute to the structure of mammalian communities. Our framework reveals that while starvation largely impacts smaller-bodied species, the allometry of senescence is expected to be more difficult to observe. In contrast, external predation and subsidized harvest primarily influence larger-bodied species. The inclusion of predation mortality reveals mass thresholds of mammalian herbivores at which dynamic instabilities limit the feasibility of megaherbivore populations. Moreover, we show how these thresholds vary with predator-prey mass ratios, a relationship that is little understood within terrestrial systems. Finally, we predict the harvest pressure required to induce mass-specific extinction, and compare these values to estimates from episodes of both paleontological and historical megafaunal exploitation.





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Justin D. Yeakel, Ph.D.
Associate Professor | University of California Merced
http://jdyeakel.github.io
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