Open Collections

Dyer, Joshua

The process by which character displacement promotes the coexistence of co-occurring species is fundamental to an understanding of evolutionary adaptation in competitive environments. Classic studies investigating character displacement assume natural selection drives niche divergence, thereby reducing interspecific competition and permitting coexistence. In contrast, recent advancements in the literature on character displacement have observed alternative outcomes, such as niche convergence, that also act to foster coexistence. However, consensus and consistent evidence between studies for the differing outcomes of divergence and convergence in promoting coexistence are lacking because of ecological assumptions proposed in classic theory and tendencies to draw inferences from trait-centric tests. It has recently been suggested that pre-existing competitive differences–which can differ based on selection and resource availability via evolution in allopatry and coevolutionary trajectories in sympatry–through competition trials may offer an explanation for the differing outcomes across studies. In this study, we investigate the hypothesis of whether pre-existing competitive differences developed in allopatry influence the competitive outcome of species pairs following coevolution in sympatry. To explore this inquiry, we paired a competition experiment with evolutionary simulations to predict changes in competitive differences between three species pairs of duckweed (Lemna minor, Lemna minuta, and Spirodela polyrhiza) from allopatric to sympatric populations. Despite the observed divergence in stabilizing differences between pairs, coinciding with diverging niches of classic theory, we provide empirical evidence of convergence from fitness differences in promoting species coexistence. In particular, we demonstrate evidence of three species pairs with differing pre-existing competitive differences that evolved to promote coexistence upon coevolution in sympatry. With accelerating changes in global climate and biodiversity driving unprecedented alterations and reconfigurations of biotic interactions, understanding how the evolution of species’ competitive interactions change through the process of character displacement is of utmost importance.

Text

University of British Columbia. ENVR 449

Vancouver : University of British Columbia Library

10.14288/1.0443955

Science, Faculty of; Earth, Ocean and Atmospheric Sciences, Department of

Undergraduate

DSpace