RUI: Limits to the Effects of Contemporary Evolution on Communities

The University Corporation, Northridge, Northridge CA

Investigators

Abstract

Ecologists have long investigated how species interacting with one another can influence biodiversity. Recently, they also have recognized that rapid, contemporary evolution can alter those species interactions. This project moves beyond asking if rapid evolution is important to asking when it is important. In some communities, it may be impossible to understand the ecology without accounting for ongoing evolutionary change. However, scientists do not yet understand the underlying rules that govern when evolution strongly influences species interactions and when it might be reasonably ignored by ecologists and conservation biologists. This project will investigate two factors that may limit the effects of rapid evolution on ecological processes: genetic diversity and dispersal. First, evolution by natural selection requires a diverse set of genes to act upon, but because genetic diversity may change over time, the influence of natural selection may also change. Second, the movement of individuals among habitats may overwhelm the ability of natural selection to purge individuals that are not well-adapted to a particular habitat. The research aims to understand how genetic diversity and dispersal shape the relative roles of contemporary evolution and ecological processes in shaping biodiversity. Results of this study could benefit society by resulting in strategies to conserve biodiversity and improve human health. Additionally, the study will involve a Latina postdoctoral associate, support graduate and undergraduate students at a Hispanic-serving institution, aid development of hands-on activities for K-5 classrooms, and continue an Ask the Scientist blog that pairs scientists with K-12 students in rural areas. Because studies of the interactions between ecological and evolutionary processes would be difficult and time-consuming to conduct using large plants and animals, this project uses a natural microcosm community as a model system to test hypotheses about genetic diversity and dispersal in the field and laboratory. The leaves of carnivorous pitcher plants contain a diverse assemblage of bacteria, protists, and insects that interact with each other ecologically, but also have very short generation times and rapid evolutionary responses to changing environmental conditions. This project will conduct experiments that create contrasting selection environments that correspond to the conditions in young and old pitcher plant leaves: high predation/low competition versus low predation/high competition, respectively. Each experiment will manipulate either the genetic diversity of protists in the community or the extent of dispersal among local communities. The researchers will then use a novel mathematical approach to distinguish ecological effects on community diversity from evolutionary effects. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.