Reproductive Ecology: A Tale of Two Sexes

Fleming, Ian A.; Einum, Sigurd

doi:10.1002/9781444327755.ch2

Cited by 55 publications

(100 citation statements)

References 170 publications

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“…Furthermore, it assumes that body size does not influence catchability in drift samplers, an assumption that may not always be satisfied (Johnston 1997). Finally, since there is pronounced variation in breeding time, and hence timing of emergence in natural populations (Fleming and Einum 2011), it is possible that drift sampling may catch mainly recently emerged juveniles, whereas larger proportions of older fish would be caught by electro-fishing. Our design, where individuals that originated from a known nest site were sampled a relatively long period after the timing of emergence, should avoid these kinds of problems.…”

Section: Discussionmentioning

confidence: 99%

“…This species reproduces primarily in streams, creating nests within the gravel bed where eggs are deposited in large numbers. This behaviour results in high local densities of propagules near the nest sites following emergence (reviewed by Fleming and Einum 2011). The spatial extent of competition among recently emerged salmon fry is over distances of ca.…”

Section: Introductionmentioning

confidence: 99%

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Natal movement in juvenile Atlantic salmon: a body size‐dependent strategy?

et al. 2011

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If competitive ability depends on body size, then the optimal natal movement from areas of high local population density can also be predicted to be size-dependent. Specifically, small, competitively-inferior individuals would be expected to benefit most from moving to areas of lower local density. Here we evaluate whether individual variation in natal movement following emergence from nests is consistent with such a size-dependent strategy in Atlantic salmon, and whether such a strategy is evident across a range of environmental conditions (principally predator presence and conspecific density). In stream channel experiments, those juveniles that stayed close to nests were larger than those that emigrated. This result was not sensitive to predator presence or conspecific density. These observations were mirrored in natural streams in which salmon eggs were planted in nests and the resulting offspring were sampled at high spatial resolution. A negative relationship was found between juvenile body size and distance from nests early in development whereas in those streams sampled later in ontogeny, individuals that had moved furthest were largest. Thus, movement away from nests appeared to result in a reduced competitive intensity and increased growth rate. The fact that there is ultimately a growth advantage associated with moving suggests that there is also a cost that selects against movement by the larger individuals. Thus, natal movement in juvenile Atlantic salmon appears to represent a body size-dependent strategy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Natal movement in juvenile Atlantic salmon: a body size‐dependent strategy?

et al. 2011

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“…Today, we have most likely identifi ed most of the factors that limit and adversely affect wild salmon stocks. Traditionally, fi eld studies and empirical fi ndings have dominated salmon ecology; more recently we have seen more experiments, especially for the freshwater phase, and even a purposely planned interplay between experiments in laboratory, semi -natural environments, and in the fi eld (see Nislow 2011 [Chapter 11 ] andFleming &Einum 2011 [Chapter 2 ] for examples). Studies of population dynamics in salmon would still benefi t a great deal from taking a stricter, more mechanistic approach towards quantitative population modelling, where the understanding of the magnitude of the different factors and how they act in concert are key issues.…”

Section: Box 173 Planning Research Programmes For Atlantic Salmonmentioning

confidence: 99%

Salmon Ecological Research and Conservation

Aas

Policansky

Einum

et al. 2010

Atlantic Salmon Ecology

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This chapter highlights contemporary challenges in Atlantic salmon research, and discusses the relationship between research and conservation. The myriad ecological and genetic studies of salmon that have been undertaken around the Northern Hemisphere over the past century and more have powerfully advanced our understanding of salmon biology. However, knowledge alone will not save salmon; only actions will. Indeed, we know enough now about salmon ecology and genetics to reverse or at least reduce the decline of many populations or protect those that have not declined. Nonetheless, we still lack important knowledge related to several aspects of salmon ecology and life -history strategies, particularly in the sea. In addition, we do not know to what degree increasing smolt production in fresh water can compensate for problems salmon face in the marine phase of their lives. Better cooperation, improved methods and technology and more carefully designed studies will help to enhance our knowledge. Salmon declines are not likely to be reversed without changes in market structures, human attitudes, institutions and political will. It would therefore be negligent of us not to emphasise the importance of interdisciplinary studies, involving our colleagues in the social sciences. With improved understanding of the interplay between humans and salmon and the environments we share, sustainable management of Atlantic salmon might be achieved. Box 17.1 Heritage rivers and fjords: A Norwegian approach to salmon conservationAtlantic salmon are divided into numerous populations and sub -populations that are subjected to densitydependent and stochastic mortality. We know that populations in more pristine environments perform better, and that interaction with humans causes many of the problems. We also know that a major threat in several regions is the combination of declining wild populations, degradation of habitat, and the increase in farmed salmon escapees. This implies that conservation interest is diminishing and commercial farming interest is

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“…Selection pressure in males, on the other hand, may be more influenced by sexual selection for access to mates, with larger males better able to court and defend females (Fleming, 1996;Fleming & Gross, 1994). However, small "sneaker" males persist as an evolutionarily stable strategy in some systems, as they are able to "steal" fertilizations from larger, more socially dominant males (Fleming & Einum, 2011).…”

Section: Introductionmentioning

confidence: 99%

Evolutionary stasis of a heritable morphological trait in a wild fish population despite apparent directional selection

O’Sullivan

Aykanat

Johnston

et al. 2019

Ecology and Evolution

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Comparing observed versus theoretically expected evolutionary responses is important for our understanding of the evolutionary process, and for assessing how species may cope with anthropogenic change. Here, we document directional selection for larger female size in Atlantic salmon, using pedigree‐derived estimates of lifetime reproductive success as a fitness measure. We show the trait is heritable and, thus, capable of responding to selection. The Breeder's Equation, which predicts microevolution as the product of phenotypic selection and heritability, predicted evolution of larger size. This was at odds, however, with the observed lack of either phenotypic or genetic temporal trends in body size, a so‐called “paradox of stasis.” To investigate this paradox, we estimated the additive genetic covariance between trait and fitness, which provides a prediction of evolutionary change according to Robertson's secondary theorem of selection (STS) that is unbiased by missing variables. The STS prediction was consistent with the observed stasis. Decomposition of phenotypic selection gradients into genetic and environmental components revealed a potential upward bias, implying unmeasured factors that covary with trait and fitness. These results showcase the power of pedigreed, wild population studies—which have largely been limited to birds and mammals—to study evolutionary processes on contemporary timescales.

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Reproductive Ecology: A Tale of Two Sexes

Cited by 55 publications

References 170 publications

Natal movement in juvenile Atlantic salmon: a body size‐dependent strategy?

Natal movement in juvenile Atlantic salmon: a body size‐dependent strategy?

Salmon Ecological Research and Conservation

Evolutionary stasis of a heritable morphological trait in a wild fish population despite apparent directional selection

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