Effective number of breeders provides a link between interannual variation in stream flow and individual reproductive contribution in a stream salmonid. Issue 14 (14th July 2015)

• Record Type: Journal Article
• Authors: Whiteley, Andrew R.; Coombs, Jason A.; Cembrola, Matthew; O'Donnell, Matthew J.; Hudy, Mark; Nislow, Keith H.; Letcher, Benjamin H.
• Is Part Of: Molecular ecology. Volume 24:Issue 14(2015)
• Page Start: 3585
• Page End: 3602
• Publication Date: 2015-07-14
• Subjects: Molecular ecology -- Periodicals; Molecular population biology -- Periodicals; 576
• DOI: 10.1111/mec.13273
• Languages: English
• ISSNs: 0962-1083

Abstract

<abstract abstract-type="main" id="mec13273-abs-0001"> <title>Abstract</title> <p>The effective number of breeders that give rise to a cohort (<italic>N</italic><sub>b</sub>) 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 <italic>N</italic><sub>b</sub> in two long‐term studies of brook trout populations. We found no supporting evidence for our initial hypothesis that <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj2fxntdrv" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09621083:media:mec13273:mec13273-math-0007" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>N</mml:mi><mml:mo stretchy="false">^</mml:mo></mml:mover><mml:mi mathvariant="normal">b</mml:mi></mml:msub></mml:math></alternatives></inline-formula> reflects <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj2fxntdk3" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09621083:media:mec13273:mec13273-math-0008" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>N</mml:mi><mml:mo stretchy="false">^</mml:mo></mml:mover><mml:mi mathvariant="normal">c</mml:mi></mml:msub></mml:math></alternatives></inline-formula> (defined as the number of adults in a population at the time of reproduction). <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj2fxntdmn" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09621083:media:mec13273:mec13273-math-0009" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>N</mml:mi><mml:mo stretchy="false">^</mml:mo></mml:mover><mml:mi mathvariant="normal">b</mml:mi></mml:msub></mml:math></alternatives></inline-formula> was stable relative to <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj2fxntg7m" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09621083:media:mec13273:mec13273-math-0010" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>N</mml:mi><mml:mo stretchy="false">^</mml:mo></mml:mover><mml:mi mathvariant="normal">C</mml:mi></mml:msub></mml:math></alternatives></inline-formula> 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 <italic>N</italic><sub>b</sub>. We observed an intermediate optimum autumn stream flow for both <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj2fxntg5h" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:09621083:media:mec13273:mec13273-math-0011" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>N</mml:mi><mml:mo stretchy="false">^</mml:mo></mml:mover><mml:mi mathvariant="normal">b</mml:mi></mml:msub></mml:math></alternatives></inline-formula> (<italic>R</italic><sup>2</sup> = 0.73, <italic>P </italic>=<italic> </italic>0.02) and full‐sibling family evenness (<italic>R</italic><sup>2</sup> = 0.77, <italic>P </italic>=<italic> </italic>0.01) in one population and a negative correlation between autumn stream flow and full‐sib family evenness in the other population (<italic>r </italic>=<italic> </italic>−0.95, <italic>P </italic>=<italic> </italic>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 <italic>N</italic><sub>b</sub> and <italic>N</italic><sub>C</sub> (so‐called genetic compensation). This work provides evidence that <italic>N</italic><sub>b</sub> is a useful metric of population‐specific individual reproductive contribution for genetic monitoring across populations and the link we provide between stream flow and <italic>N</italic><sub>b</sub> could be used to help predict population resilience to environmental change.</p> </abstract>