Using IPMs to address questions in ecology and evolution

Dr Dylan Childs from the University of Sheffield will present the Department of Biological Sciences seminar with a talk entitled,  "Using IPMs to address questions in ecology and evolution".

Integral Projection Models (IPMs) are a flexible tool for understanding the causes and consequences of individual trait variation. I will give a brief overview of the IPM and then illustrate its use in two applications. The first investigates how fluctuations in demographic structure and phenotypic trait distributions mediate population responses to the environment. I show how to partition the contributions to population growth arising from variation in (1) survival and reproduction, (2) demographic structure, (3) trait values and (4) climatic drivers. I then apply this method to a population of yellow‐bellied marmots to investigate the role of demographic buffering, which may be a more subtle phenomenon than is currently assumed. In a second application of the IPM, I investigate how demographic constraints can lead to apparent trade-offs in comparative life-history analyses. In recent years, reanalyses of published matrix population models (MPMs) have identified patterns of life-history variation that appear to fall onto to a fast-slow continuum and a reproductive strategy axis. We simulated size-structured integral projection models (IPMs) under a simple constraint that the long-term growth rate is close to one. We find that a PCA of life history metrics derived from the simulated models produced patterns of life-history trait covariance that are very similar to the relationships seen in empirical data. These results indicate that comparative analysis of MPM-derived life-history traits may not identify meaningful life-history trade-offs and that a significant component of the covariance among MPM-derived life history metrics is consistent with non-adaptive processes.

Tue, 17 Sep 2019 - 13:00

Niven Library, Department of Biological Sciences, Upper Campus, UCT