Abstract
Why in some cases does evolution favor a single solution to an environmental challenge, while in other cases multiple solutions emerge? Laboratory investigations indicate that solutions, even those that are complex, can evolve in a path-dependent (contingent) manner that is part predictable and part stochastic. Path dependence results in multiple, functionally equivalent solutions when outcomes are limited by critical junctions, key events in trait evolution that constrain future paths. Identifying critical junctions in natural systems is challenging because most natural traits offer only a single evolutionary history to examine, and most convergences occur across animals with differing body plans and ecologies. To address this challenge, we can turn to separate origins of similar traits via convergent evolution, which can function similarly to replicates in laboratory experiments by providing multiple pathways to compare. I will describe two functionally similar but mutually exclusive solutions to the evolution of distributed visual systems in chitons (Mollusca; Polyplacophora). I will then point out a critical junction in trait evolution that dictates the type of visual system a lineage of chitons can evolve, indicating a mechanism for path dependence in a natural system. Path dependence increases the predictability of evolution by restricting solutions to discrete possibilities. Reducing the range of options offered by random chance can favor multiple, equivalent solutions.
About Dr Rebecca Varney
Rebecca is a postdoctoral researcher at the University of California, Santa Barbara, in the Oakley research lab. She studies the evolutionary origin of novelty and innovation using extreme survivors to better understand the limits of life. She uses a combination of traditional physiological approaches and the latest 'omics techniques. She is interested in the interplay between genotype, phenotype, and the environment.
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