A Stochastic Model for Annual Reproductive Success

Kendall, Bruce E.; Wittmann, Marion E.

doi:10.1086/650724

Cited by 43 publications

(60 citation statements)

References 32 publications

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“…Many models of population growth are non-linear functions of individual fitness [86]. Consequently, among-individual variation in fecundity or survival alters mean population growth and abundance.…”

Section: Examples Of Non-linear Functions Of Variable Traitsmentioning

confidence: 99%

Why intraspecific trait variation matters in community ecology

Bolnick¹,

Amarasekare²,

Araújo³

et al. 2011

Trends in Ecology & Evolution

1,939

2,073

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Natural populations consist of phenotypically diverse individuals that exhibit variation in their demographic parameters and intra-and interspecific interactions. Recent experimental work suggests that such variation can have significant ecological effects. However, ecological models typically disregard this variation and focus instead on trait means and total population density. Under what situations is this simplification appropriate? Why might intraspecific variation alter ecological dynamics? In this review, we synthesize recent theory, identifying six general mechanisms by which trait variation changes the outcome of ecological interactions. These include several direct effects of trait variation per se, and indirect effects arising from genetic variation's role in trait evolution.

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Section: Examples Of Non-linear Functions Of Variable Traitsmentioning

confidence: 99%

Why intraspecific trait variation matters in community ecology

Bolnick¹,

Amarasekare²,

Araújo³

et al. 2011

Trends in Ecology & Evolution

1,939

2,073

View full text Add to dashboard Cite

show abstract

“…In this study, we have worked with the standard assumption of Poisson-distributed offspring numbers. However, there is evidence that many natural populations do not conform to this assumption (Kendall and Wittmann 2010). Especially in small populations with an Allee effect, we would expect more variation in offspring number because many individuals do not encounter a mating partner (Kramer et al 2009), whereas those that do can exploit abundant resources and produce a large number of offspring.…”

Section: Discussionmentioning

confidence: 98%

Genetic Diversity in Introduced Populations with an Allee Effect

Wittmann

Gabriel²,

Metzler³

2014

Genetics

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A phenomenon that strongly influences the demography of small introduced populations and thereby potentially their genetic diversity is the demographic Allee effect, a reduction in population growth rates at small population sizes. We take a stochastic modeling approach to investigate levels of genetic diversity in populations that successfully overcame either a strong Allee effect, in which populations smaller than a certain critical size are expected to decline, or a weak Allee effect, in which the population growth rate is reduced at small sizes but not negative. Our results indicate that compared to successful populations without an Allee effect, successful populations with a strong Allee effect tend to (1) derive from larger founder population sizes and thus have a higher initial amount of genetic variation, (2) spend fewer generations at small population sizes where genetic drift is particularly strong, and (3) spend more time around the critical population size and thus experience more genetic drift there. In the case of multiple introduction events, there is an additional increase in diversity because Allee-effect populations tend to derive from a larger number of introduction events than other populations. Altogether, a strong Allee effect can either increase or decrease genetic diversity, depending on the average founder population size. By contrast, a weak Allee effect tends to decrease genetic diversity across the entire range of founder population sizes. Finally, we show that it is possible in principle to infer critical population sizes from genetic data, although this would require information from many independently introduced populations.T HE amount of genetic diversity in a recently established population is strongly shaped by its early history: While the founder population size determines the amount of genetic variation imported from the source population, the population sizes in the following generations influence how much of this variation is maintained and how much is lost through genetic drift. A phenomenon that strongly affects the early history is the demographic Allee effect, a reduction in the average per-capita growth rate in small populations (Stephens et al. 1999;Fauvergue et al. 2012). Allee effects have been detected in species from many different taxonomic groups (Kramer et al. 2009). Apart from cooperation between individuals, the study subject of the effect's eponym (Allee 1931), they can result from a variety of other mechanisms such as difficulties in finding mating partners, increased predation pressure in small populations, inbreeding depression, or biased dispersal toward large populations (Stephens et al. 1999;Kramer et al. 2009). In this study, we investigate the population genetic consequences of two kinds of demographic Allee effect: Our main focus is on the strong demographic Allee effect, in which the average per-capita growth rate is negative for populations smaller than a certain critical population size, but we also consider the weak demographic Allee eff...

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“…There are only a few models that take more than one level into account (e.g. [48,49]), but to our knowledge there are none that consider all the levels used in this study together. Moreover, males and females have only rarely been modelled simultaneously in other studies of divorce or mate retention before (e.g.…”

Section: Discussionmentioning

confidence: 99%

Better the devil you know: common terns stay with a previous partner although pair bond duration does not affect breeding output

2017

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In a monogamous species two partners contribute to the breeding process. We study pair formation as well as the effect of pair bond length and age on breeding performance, incorporating individual heterogeneity, based on a high-quality dataset of a long-lived seabird, the common tern ( Sterna hirundo ). To handle missing information and model the complicated processes driving reproduction, we use a hierarchical Bayesian model of the steps that lead to the number of fledglings, including processes at the individual and the pair level. The results show that the age of both partners is important for reproductive performance, with similar patterns for both sexes and individual heterogeneity in reproductive performance, but pair bond length is not. The terns are more likely to choose a former partner independent of the previous breeding outcome with that partner, which suggests a tendency to retain the partner chosen at the beginning of the breeding career.

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A Stochastic Model for Annual Reproductive Success

Cited by 43 publications

References 32 publications

Why intraspecific trait variation matters in community ecology

Why intraspecific trait variation matters in community ecology

Genetic Diversity in Introduced Populations with an Allee Effect

Better the devil you know: common terns stay with a previous partner although pair bond duration does not affect breeding output

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