CAREER: Does behavioral plasticity promote or constrain adaptation? A test using resurrection.

University Of Texas At Arlington, Arlington TX

Investigators

Abstract

Organisms respond to changes in the environment by altering the expression of traits. The manner in which such changes facilitate or impede the ability of organisms to evolve and ultimately persist in changing environments is unclear. This project takes advantage of a unique feature of zooplankton biology to directly observe and to quantify rapid evolutionary responses when conditions change. This project will resurrect zooplankton from Wisconsin lakes that recently experienced a dramatic shift in the environment (i.e., invasion by a novel predator). This will allow the PI to track the interplay between environmentally-induced trait responses and evolutionary changes in "real time." Such an approach will provide novel insights into how organisms adapt to a change in the environment. This program of research will be combined with an educational plan that uses zooplankton as a model to engage students with inquiry-based curricula and research based courses. This project will support graduate and undergraduate students at a Hispanic Serving Institution (UTA). The concepts stemming from this project with be used to create outreach modules to convey evolution by natural selection to the general public at highly visible events in Texas. The role that environmentally-induced phenotypic plasticity plays in adaptive evolution has been debated for decades. Does plasticity shield genotypes from selection following a novel shift in the environment and, in turn, impede adaptation? Or does phenotypic plasticity accelerate the rate at which populations attain new fitness peaks and thereby facilitate adaptation? Answers to these questions largely remain unresolved because few studies are able to assess plasticity in ancestral lineages directly and to track phenotypic responses following a shift in the environment. This project will address these questions by resurrecting historic propagules of zooplankton from lakes in Wisconsin following a recent shift in ecologically-mediated selection. Multiple Wisconsin lakes were recently invaded by a novel invertebrate predator (spiny waterflea). Comparisons across contemporary populations show that invasion by spiny waterfleas is associated with rapid evolution of Daphnia prey. This project pairs 'resurrection experiments' with experimental evolution in the lab to determine if plasticity promotes or impedes adaptation. The PI will specifically: (1) determine how historical changes in selection shapes the expression of plasticity including transgenerational plasticity, (2) experimentally test whether plasticity facilitates or constrains adaptation, and (3) evaluate the connection between evolutionary shifts in trait values and trait plasticity and fitness. These approaches will provide novel insights into how organisms adapt to a change in the environment including a test of the longstanding hypothesis regarding the role of behavior in evolution (i.e., the behavior evolves first hypothesis).