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Effective number of breeders provides a link between interannual variation in stream flow and individual reproductive contribution in a stream salmonid
Author(s) -
Whiteley Andrew R.,
Coombs Jason A.,
Cembrola Matthew,
O'Donnell Matthew J.,
Hudy Mark,
Nislow Keith H.,
Letcher Benjamin H.
Publication year - 2015
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 - 10.1111/mec.13273
Subject(s) - biology , population , species evenness , reproduction , reproductive success , gene flow , trout , relative species abundance , ecology , abundance (ecology) , genetic variation , demography , fish <actinopterygii> , genetics , species diversity , fishery , sociology , gene
The effective number of breeders that give rise to a cohort ( N b ) is a promising metric for genetic monitoring of species with overlapping generations; however, more work is needed to understand factors that contribute to variation in this measure in natural populations. We tested hypotheses related to interannual variation in N b in two long‐term studies of brook trout populations. We found no supporting evidence for our initial hypothesis thatN ^ b reflectsN ^ c (defined as the number of adults in a population at the time of reproduction).N ^ b was stable relative toN ^ C and did not follow trends in abundance (one stream negative, the other positive). We used stream flow estimates to test the alternative hypothesis that environmental factors constrain N b . We observed an intermediate optimum autumn stream flow for bothN ^ b ( R 2 = 0.73, P = 0.02) and full‐sibling family evenness ( R 2 = 0.77, P = 0.01) in one population and a negative correlation between autumn stream flow and full‐sib family evenness in the other population ( r = −0.95, P = 0.02). Evidence for greater reproductive skew at the lowest and highest autumn flow was consistent with suboptimal conditions at flow extremes. A series of additional tests provided no supporting evidence for a related hypothesis that density‐dependent reproductive success was responsible for the lack of relationship between N b and N C (so‐called genetic compensation). This work provides evidence that N b is a useful metric of population‐specific individual reproductive contribution for genetic monitoring across populations and the link we provide between stream flow and N b could be used to help predict population resilience to environmental change.