Grantee Research Project Results
2003 Progress Report: How Likely is it That Fish Populations Will Successfully Adapt to Global Warming?
EPA Grant Number: R829420E02Title: How Likely is it That Fish Populations Will Successfully Adapt to Global Warming?
Investigators: Klerks, Paul L. , Leberg, Paul L.
Institution: University of Louisiana at Lafayette
EPA Project Officer: Chung, Serena
Project Period: June 10, 2002 through June 9, 2004 (Extended to June 9, 2006)
Project Period Covered by this Report: June 10, 2003 through June 9, 2004
Project Amount: $121,598
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2001) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
The objective of this research project is to investigate how likely it is that populations of fish will adapt successfully to temperature changes associated with global warming. This is being addressed for both normal populations and populations that have undergone a drastic reduction in population size. A major factor determining the long-term ecological effects of global warming is whether organisms will be able to adapt to global warming. Successful adaptation would mean that global warming does not displace species from their current habitats. Distribution shifts and extinctions would occur if the organisms fail to adapt to deleterious effects of global warming. At present, there is insufficient information to predict almost any species’ evolutionary response to climate change. The question is of special importance to the southeastern United States, as organisms in warm waters may already be living close to their temperature tolerance limit and because of the importance of fishery resources to the region’s economy.
Progress Summary:
Selection Experiment
The selection experiment is being conducted with normal populations and populations that have undergone drastic reductions in population size (“bottlenecked populations”; each started with a single pair of fish). Previously, we established the greenhouse fish culturing facility (with a total of 28 population trays) and 12 base populations (6 for the least killifish Heterandria formosa, 6 for the western mosquitofish Gambusia affinis). Each set of six populations was started with fish from three different locations in Louisiana. It took substantial time before the bottlenecked populations reached a sufficient size to start the selection process (population size had to increase from 2 to 120 adults). The bottlenecked H. formosa populations reached the desired size early on in this reporting period, thus allowing us to divide the 6 base populations into the 12 starting populations (6 control and 6 selection populations) and starting the least killifish selection process. We still were conducting the resistance quantifications and selection for the first generation by the end of this reporting period (though this has since been completed for eight populations, and we have started the process for the next generation in two populations). For the G. affinis populations, we still are waiting for some of the bottlenecked populations to reach the required size (reproduction in this species started later in the spring than it did in H. formosa). For quantifying the effect of the population bottlenecks on genetic variation, we have completed the development of microsatellites to be used in this quantification. Polymerase chain reaction amplification using a total of 27 primers based on three related species showed that 13 of them were amplified consistently in H. formosa. We are using the seven loci with most alleles per locus. Microsatellite primers for the western mosquitofish were developed earlier ( Spencer, et al., 2000).
Quantifying Heritability of Temperature Tolerance
We are in the process of determining the heritability of temperature tolerance in four least killifish populations (two normal and two inbred populations). Fish were set up in pairs of newborn fish, and offspring of these fish are being obtained. For those pairs where we have enough offspring, temperature tolerance of both parents and offspring is being quantified (allowing us to use the resemblance among relatives to quantify the heritability).
Comparison of Temperature Tolerance Between Populations From Environments With Different Temperature Regimes
We have sampled about 16 sites in Florida, including sites receiving heated water from power plants, sites receiving cool or hot water from constant-temperature natural springs, and sites with an ambient thermal regime. Many of these sites did not have any least killifish, although the eastern mosquitofish G. holbrooki was generally abundant at all sites. We have collected least killifish at two sites and eastern mosquitofish at six sites. Fish were exposed in the laboratory to a gradually increasing temperature (2°C/day, starting at 28°C)to quantify temperature tolerance. Analyses of the results indicated a lack of difference in temperature tolerance among the populations for each of the four pairs of sites with different thermal regimes. For the last set of populations, we collected a large number of fish, exposed only a subset of the collected fish, and used the remaining fish to set up laboratory cultures. This will allow us to compare temperature tolerance after two generations in the laboratory (which will reduce environmental influences on temperature tolerance).
Reference:
Spencer CC, Neigel JE, Leberg PL. Experimental evaluation of the usefulness of microsatellite DNA for detecting demographic bottlenecks. Molecular Ecology 2000;9(10):1517-1528.
Future Activities:
Comparison of Temperature Tolerance Among Populations From Environments With Different Temperature Regimes
We will complete the comparison of temperature tolerance among Florida populations using the eastern mosquitofish G. holbrooki populations that are being maintained in the laboratory for two generations. Because our Florida field observations indicate that this species may be especially capable of maintaining populations in extreme environments, we have included this species in our survey. We also will include the comparison of temperature tolerance among three sets of populations of the western mosquitofish.
Selection Experiment
For the least killifish, we now have quantified resistance in generation 0 and selected the fish to be used as parents for the next generation for the selection lines. This process will be continued for subsequent generations. Once the western mosquitofish bottlenecked populations have reached a population size of 120 adults (60 of each sex), the same process will be used for this species. We will continue our analyses of genetic variation (using microsatellites) in both normal and bottlenecked populations (in generation 0) and will expand this later to control lines and selection lines (in later generations, once resistance has evolved). We also will continue quantifying the heritability of resistance in the 12 original (normal and bottlenecked) populations.
Journal Articles:
No journal articles submitted with this report: View all 8 publications for this projectSupplemental Keywords:
global climate, ecological effects, vulnerability, aquatic, ecology, temperature, adaptation, genetic variation, air, geographic area, atmospheric sciences, ecological risk assessment, ecology and ecosystems, environmental monitoring, hydrology, state, climate change, global climate change, Louisiana, LA, aquatic ecology, climate models, climate variability, fish habitat, genetic diversity, global change, global warming, land and water resources, watershed,, RFA, Scientific Discipline, Air, Geographic Area, Hydrology, climate change, State, Environmental Monitoring, Atmospheric Sciences, Ecological Risk Assessment, wetlands, fish habitat, watershed, global change, Louisiana (LA), coastal ecosystems, aquatic ecology, global warming, land and water resources, climate variability, Global Climate ChangeRelevant Websites:
http://www.louisiana.edu/Departments/BIOL/klerks.html Exit
http://www.louisiana.edu/Departments/BIOL/leberg.html Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.