Sierra Nevada Aquatic Research Laboratory

24 May, 11 AM - 15 Jul, 02 AM

Natural populations of organisms often fluctuate greatly over brief time spans, and evolutionary changes within species may occur rapidly. Population ecologists have made great strides in understanding factors that mediate fluctuations in population size, and evolutionary biologists have gained significant insights into the process of natural selection. Few studies have investigated the consequences of genetic variation on the ecology of native organisms. Bridging this gap in our understanding is urgent, as we are now experiencing broad and profound impacts of climate change on natural ecosystems, and have little power to predict which features of organisms might allow them to persist in a changing environment, instead of being forced to disperse or face local extinction. We are 3 years into a 5-year NSF award, in which we are integrating population genetic and experimental ecological approaches to study the response to climate change in the willow leaf beetle Chrysomela aeneicollis. This investigation is building on a long record of ecological, physiological and genetic research in this system. Beetles live at high elevations in the Eastern Sierra Nevada Mountains of California, where the growing season is short and levels of precipitation unpredictable. We have detailed knowledge of the food web ecology, natural history, and temperature biology of this organism, and have documented changes in distribution and abundance of beetle populations in response to environmental variation. We have observed that genetic variation at an allozyme locus, phosphoglucose isomerase (PGI), is consistently related to differences in thermal tolerance, survival, performance, and reproductive success among genotypes, providing us with a genetic marker for temperature adaptation. Finally, we have evidence that beetle populations are genetically differentiated, allowing us to conduct experimental manipulations that test the relative contributions of genetic and biotic forces on responses of populations to environmental change. Our study includes observational and experimental components. First, we quantify the genetic composition of populations of known history, over time, using microsatellite and allozyme markers. We include historical, archived populations, some of which have now gone extinct, in this analysis. As new localities are colonized, we analyze these new populations to identify their origin. Genetic data are correlated with natural fluctuations in micro-habitat environmental conditions (for example temperature, soil moisture and snowmelt date) and population size to identify genetic and environmental factors that relate to dynamics of natural populations. Second, we identify mechanisms contributing to changes in population size using manipulative experiments that measure three key components of population growth and persistence: female fecundity, larval survival, and over-wintering survival of new adults. Larval survival will be measured in the presence and absence of natural enemies known to impact beetle population size. Finally, we assess the relationship between variation at PGI and population persistence. Together, these experiments allow us to evaluate the effects of genetic variation, biotic interactions and abiotic stress on population persistence. By carrying out this work over the next 10 years, we will have the opportunity to observe the ecological and evolutionary mechanisms underlying biotic responses to climate change at a time-scale that matches the known history of past population expansion and decline. A FULL DESCRIPTION OF THIS PROJECT IS IN OUR AWARDED NSF PROPOSAL, WHICH I AM HAPPY TO PROVIDE THE MANAGER ON REQUEST. NONE OF THIS WORK WILL BE CONDUCTED ON RESERVE PROPERTY. WE HAVE ALL RELEVANT COLLECTING AND SPECIAL USE PERMITS TO WORK IN INYO NATIONAL FOREST AND JOHN MUIR WILDERNESS.

Visit #27357 @Sierra Nevada Aquatic Research Laboratory

Approved

Under Project # 24846 | Research

Ecological and evolutionary responses to climate change in Sierra Nevada populations of a montane willow beetle

faculty - Santa Clara University

Reservation Members(s)

Nathan Rank Jul 1 - 14, 2012 (14 days)
Group of 2 Faculty May 24 - Jul 15, 2012 (53 days)
Group of 4 Undergraduate Student May 24 - Jul 15, 2012 (53 days)

Reserve Resources(s) | Create Invoice