Selection for increased body length in Subantarctic fur seals on Amsterdam Island

Authier, Matthieu; Cam, Emmanuelle; Guinet, Christophe

doi:10.1111/j.1420-9101.2010.02193.x

Cited by 9 publications

(12 citation statements)

References 57 publications

(114 reference statements)

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“…As this population has reached its carrying capacity, the intraspecific competition level should accordingly be higher in the Amsterdam population than at Crozet (Gilpin & Ayala ). In addition, Authier, Cam & Guinet () have reported that the probability of breeding success has decreased in Amsterdam as the population has stabilized, most probably as a consequence of increasing competition. Therefore, the impact of interspecific competition in the subantarctic fur seal (sympatry in Crozet, allopatry in Amsterdam) may be masked by effects of contrasted level of intraspecific competition between the two populations and has not been investigated in this species.…”

Section: Discussionmentioning

confidence: 99%

Determinants of individual foraging specialization in large marine vertebrates, the Antarctic and subantarctic fur seals

Kernaléguen

Arnould

Guinet

et al. 2015

Journal of Animal Ecology

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Summary1. The degree of individual specialization in resource use differs widely among wild populations where individuals range from fully generalized to highly specialized. This interindividual variation has profound implications in many ecological and evolutionary processes. A recent review proposed four main ecological causes of individual specialization: interspecific and intraspecific competition, ecological opportunity and predation. 2. Using the isotopic signature of subsampled whiskers, we investigated to what degree three of these factors (interspecific and intraspecific competition and ecological opportunity) affect the population niche width and the level of individual foraging specialization in two fur seal species, the Antarctic and subantarctic fur seals (Arctocephalus gazella and Arctocephalus tropicalis), over several years. 3. Population niche width was greater when the two seal species bred in allopatry (low interspecific competition) than in sympatry or when seals bred in high-density stabilized colonies (high intraspecific competition). In agreement with the niche variation hypothesis (NVH), higher population niche width was associated with higher interindividual niche variation. However, in contrast to the NVH, all Antarctic females increased their niche width during the interbreeding period when they had potential access to a wider diversity of foraging grounds and associated prey (high ecological opportunities), suggesting they all dispersed to a similar productive area. 4. The degree of individual specialization varied among populations and within the annual cycle. Highest levels of interindividual variation were found in a context of lower interspecific or higher intraspecific competition. Contrasted results were found concerning the effect of ecological opportunity. Depending on seal species, females exhibited either a greater or lower degree of individual specialization during the interbreeding period, reflecting species-specific biological constraints during that period. 5. These results suggest a significant impact of ecological interactions on the population niche width and degree of individual specialization. Such variation at the individual level may be an important factor in the species plasticity with significant consequences on how it may respond to environmental variability.

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Section: Discussionmentioning

confidence: 99%

Determinants of individual foraging specialization in large marine vertebrates, the Antarctic and subantarctic fur seals

Kernaléguen

Arnould

Guinet

et al. 2015

Journal of Animal Ecology

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“…A question currently receiving growing attention is the extent to which morphological (e.g., structural size), physiological (e.g., body condition) and personality traits are determined genetically and are heritable (e.g., Authier et al 2011;Dingemanse et al 2004;Dingemanse and Réale 2005;Drent et al 2003;Garnett 1981;Kontiainen et al 2007;Larsson and Forslund 1992;Larsson 1993;Merilä et al 2001;Réale and Festa-Bianchet 2003;Schlutter and Gustafsson 1993;Stamps and Groothuis 2010;Téplitsky et al 2008;van Noordwijk et al 1988;van Oers et al 2005). Similarly, fitness components themselves may be heritable (e.g., Charmantier et al 2006a, b;Kontiainen et al 2007).…”

Section: Heritability and Parental Effectsmentioning

confidence: 99%

Early development, recruitment and life history trajectory in long-lived birds

Cam

Aubry

2011

J Ornithol

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International audienceLindström (in Trends Ecol Evol 14:343-347, 1999) synthesized knowledge about "early development and fitness in birds and mammals", interesting tracks and challenges for future studies. Today, there is unambiguous evidence that Lindström's first statement holds in long-lived birds: "It is obvious that adverse environmental conditions might have immediate effects [...]." However, whether there are "long-term fitness consequences of conditions experienced during early development" (Lindström's second statement) is unclear for long-lived birds. The extent to which the disadvantage of frail individuals at independence is expressed predominantly in terms of higher mortality and disappearance from the population before recruitment, or persists after recruitment, is still an open question. Due to the rarity of relevant data and the fact that most studies are retrospective, heterogeneity in methods and timescales hampers the identification of general patterns. Nevertheless, several studies have provided evidence of a relationship between early conditions and future reproductive parameters, or lifetime reproductive success. Evidence from large mammals suggests substantial long-term individual and population effects of early conditions, including trans-generational maternal effects. Evidence from short-lived birds also suggests long-term individual consequences, and maternal effects have been documented in long-lived ones. Despite logistical and financial difficulties inherent in long-term studies, they are the only way of addressing Lindström's second statement. Existing long-term longitudinal datasets should be re-analyzed using recently developed capture-mark-recapture models handling state uncertainty and unobservable heterogeneity in populations. Statistical methods designed to estimate lifetime reproductive success or incorporate pedigree information in standard situations of studies of wild vertebrates with imperfect detection offer new opportunities to assess long-term fitness consequences of early development in long-lived birds

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“…The parameters

σ_{ϕ}^{2}

and

σ_{normalrepro}^{2}

are variance parameters, and

normalcor

is a correlation parameter bounded between −1 and 1. The multivariate normal distribution was used for convenience as often in empirical investigations (e.g., Authier, Cam, & Guinet, ; Browne, McCleery, Sheldon, & Pettifor, ; Cam et al., ).…”

Section: Notationsmentioning

confidence: 99%

Wolf in sheep's clothing: Model misspecification undermines tests of the neutral theory for life histories

Authier

Aubry

Cam

2017

Ecology and Evolution

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Understanding the processes behind change in reproductive state along life‐history trajectories is a salient research program in evolutionary ecology. Two processes, state dependence and heterogeneity, can drive the dynamics of change among states. Both processes can operate simultaneously, begging the difficult question of how to tease them apart in practice. The Neutral Theory for Life Histories (NTLH) holds that the bulk of variations in life‐history trajectories is due to state dependence and is hence neutral: Once previous (breeding) state is taken into account, variations are mostly random. Lifetime reproductive success (LRS), the number of descendants produced over an individual's reproductive life span, has been used to infer support for NTLH in natura. Support stemmed from accurate prediction of the population‐level distribution of LRS with parameters estimated from a state dependence model. We show with Monte Carlo simulations that the current reliance of NTLH on LRS prediction in a null hypothesis framework easily leads to selecting a misspecified model, biased estimates and flawed inferences. Support for the NTLH can be spurious because of a systematic positive bias in estimated state dependence when heterogeneity is present in the data but ignored in the analysis. This bias can lead to spurious positive covariance between fitness components when there is in fact an underlying trade‐off. Furthermore, neutrality implied by NTLH needs a clarification because of a probable disjunction between its common understanding by evolutionary ecologists and its translation into statistical models of life‐history trajectories. Irrespective of what neutrality entails, testing hypotheses about the dynamics of change among states in life histories requires a multimodel framework because state dependence and heterogeneity can easily be mistaken for each other.

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Selection for increased body length in Subantarctic fur seals on Amsterdam Island

Cited by 9 publications

References 57 publications

Determinants of individual foraging specialization in large marine vertebrates, the Antarctic and subantarctic fur seals

Determinants of individual foraging specialization in large marine vertebrates, the Antarctic and subantarctic fur seals

Early development, recruitment and life history trajectory in long-lived birds

Wolf in sheep's clothing: Model misspecification undermines tests of the neutral theory for life histories

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