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Demographic and genetic estimates of effective population size ( N e ) reveals genetic compensation in steelhead trout
Author(s) -
Ardren William R.,
Kapuscinski Anne R.
Publication year - 2003
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2003.01705.x
Subject(s) - biology , effective population size , population , inbreeding , linkage disequilibrium , genetic drift , genetic variation , population size , genetic variability , population bottleneck , evolutionary biology , microsatellite , ecology , demography , genetics , allele , genotype , sociology , gene , haplotype
Estimates of effective population size ( N e ) are required to predict the impacts of genetic drift and inbreeding on the evolutionary dynamics of populations. How the ratio of N e to the number of sexually mature adults ( N ) varies in natural vertebrate populations has not been addressed. We examined the sensitivity of N e / N to fluctuations of N and determined the major variables responsible for changing the ratio over a period of 17 years in a population of steelhead trout ( Oncorhynchus mykiss ) from Washington State. Demographic and genetic methods were used to estimate N e . Genetic estimates of N e were gained via temporal and linkage disequilibrium methods using data from eight microsatellite loci. DNA for genetic analysis was amplified from archived smolt scales. The N e / N from 1977 to 1994, estimated using the temporal method, was 0.73 and the comprehensive demographic estimate of N e / N over the same time period was 0.53. Demographic estimates of N e indicated that variance in reproductive success had the most substantial impact on reducing N e in this population, followed by fluctuations in population size. We found increased N e / N ratios at low N , which we identified as genetic compensation. Combining the information from the demographic and genetic methods of estimating N e allowed us to determine that a reduction in variance in reproductive success must be responsible for this compensation effect. Understanding genetic compensation in natural populations will be valuable for predicting the effects of changes in N (i.e. periods of high population density and bottlenecks) on the fitness and genetic variation of natural populations.