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Population size is weakly related to quantitative genetic variation and trait differentiation in a stream fish
Author(s) -
Wood Jacquelyn L. A.,
Tezel Defne,
Joyal Destin,
Fraser Dylan J.
Publication year - 2015
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12733
Subject(s) - biology , genetic drift , population size , genetic variation , population , small population size , trait , effective population size , evolutionary biology , genetic variability , habitat fragmentation , ecology , habitat , genetics , demography , genotype , sociology , gene , computer science , programming language
How population size influences quantitative genetic variation and differentiation among natural, fragmented populations remains unresolved. Small, isolated populations might occupy poor quality habitats and lose genetic variation more rapidly due to genetic drift than large populations. Genetic drift might furthermore overcome selection as population size decreases. Collectively, this might result in directional changes in additive genetic variation ( V A ) and trait differentiation ( Q ST ) from small to large population size. Alternatively, small populations might exhibit larger variation in V A and Q ST if habitat fragmentation increases variability in habitat types. We explored these alternatives by investigating V A and Q ST using nine fragmented populations of brook trout varying 50‐fold in census size N (179–8416) and 10‐fold in effective number of breeders, N b (18–135). Across 15 traits, no evidence was found for consistent differences in V A and Q ST with population size and almost no evidence for increased variability of V A or Q ST estimates at small population size. This suggests that (i) small populations of some species may retain adaptive potential according to commonly adopted quantitative genetic measures and (ii) populations of varying sizes experience a variety of environmental conditions in nature, however extremely large studies are likely required before any firm conclusions can be made.