The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Nicholas A J Graham - One of the best experts on this subject based on the ideXlab platform.
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Habitat structure and body size distributions: cross- ecosystem comparison for taxa with determinate and Indeterminate Growth
Oikos, 2014Co-Authors: Kirsty L. Nash, Craig R Allen, Shana M. Sundstrom, Chris Barichievy, Magnus Nyström, Nicholas A J GrahamAbstract:Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate Growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with Indeterminate Growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate Growth) and fish (Indeterminate Growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size-density relationships (SSDRs) and individual size-density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat-size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate Growth, such as birds. In contrast, for species with Indeterminate Growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.
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Habitat structure and body size distributions: cross‐ecosystem comparison for taxa with determinate and Indeterminate Growth
Oikos, 2014Co-Authors: Kirsty L. Nash, Craig R Allen, Shana M. Sundstrom, Chris Barichievy, Magnus Nyström, Nicholas A J GrahamAbstract:Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate Growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with Indeterminate Growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate Growth) and fish (Indeterminate Growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size-density relationships (SSDRs) and individual size-density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat-size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate Growth, such as birds. In contrast, for species with Indeterminate Growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.
Ronald J. Brooks - One of the best experts on this subject based on the ideXlab platform.
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subtle individual variation in Indeterminate Growth leads to major variation in survival and lifetime reproductive output in a long lived reptile
Functional Ecology, 2018Co-Authors: Doug P. Armstrong, Njal Rollinson, Matthew G. Keevil, Ronald J. BrooksAbstract:Summary 1.The consequences of individual variation in life-history traits have been well studied due to their importance in evolutionary ecology. However, a trait that has received little empirical attention is the rate of Indeterminate Growth. In long-lived ectotherms, subtle variation in Growth after maturity could have major effects over the animals’ lifetimes. 2.These effects are difficult to measure due to the challenges involved in reliably estimating individual variation in the face of environmental stochasticity, and the need to account for trade-offs among Growth, reproduction and survival. However, modelling advances have made such analysis possible if long-term high-quality data sets are available. 3.We used an integrated state-space modelling framework to reveal relationships between Indeterminate Growth, reproduction and survival in a population of North American snapping turtles (Chelydra serpentina) using a 41-year data set for 298 adult females. 4.A hierarchical version of the von Bertalanffy model fitted to data on carapace lengths showed substantial individual variation in Growth trajectories, and hierarchical models fitted to clutch-mass data and recapture histories showed that reproductive output and survival probability increased with size. Integration of these models revealed no detectable trade-offs – i.e., individual Growth parameters were not correlated with size-specific survival or reproduction rates, and individual variation in reproductive output did not affect the size-specific survival rate. Consequently, individual variation in Growth parameters was estimated to result in > 2-fold variation in post-maturity life expectancy and > 4-fold variation in expected lifetime reproductive output. 5.These results illustrate that Indeterminate Growth can have major fitness consequences in long-lived species. We suggest that the individual variation in Growth rates reflects variation in environments experienced during development or later life. An understanding of this variation may be essential for predicting the population dynamics of long-lived species under threat and identifying the most important environments to protect. This article is protected by copyright. All rights reserved.
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Subtle individual variation in Indeterminate Growth leads to major variation in survival and lifetime reproductive output in a long‐lived reptile
Functional Ecology, 2017Co-Authors: Doug P. Armstrong, Njal Rollinson, Matthew G. Keevil, Ronald J. BrooksAbstract:Summary 1.The consequences of individual variation in life-history traits have been well studied due to their importance in evolutionary ecology. However, a trait that has received little empirical attention is the rate of Indeterminate Growth. In long-lived ectotherms, subtle variation in Growth after maturity could have major effects over the animals’ lifetimes. 2.These effects are difficult to measure due to the challenges involved in reliably estimating individual variation in the face of environmental stochasticity, and the need to account for trade-offs among Growth, reproduction and survival. However, modelling advances have made such analysis possible if long-term high-quality data sets are available. 3.We used an integrated state-space modelling framework to reveal relationships between Indeterminate Growth, reproduction and survival in a population of North American snapping turtles (Chelydra serpentina) using a 41-year data set for 298 adult females. 4.A hierarchical version of the von Bertalanffy model fitted to data on carapace lengths showed substantial individual variation in Growth trajectories, and hierarchical models fitted to clutch-mass data and recapture histories showed that reproductive output and survival probability increased with size. Integration of these models revealed no detectable trade-offs – i.e., individual Growth parameters were not correlated with size-specific survival or reproduction rates, and individual variation in reproductive output did not affect the size-specific survival rate. Consequently, individual variation in Growth parameters was estimated to result in > 2-fold variation in post-maturity life expectancy and > 4-fold variation in expected lifetime reproductive output. 5.These results illustrate that Indeterminate Growth can have major fitness consequences in long-lived species. We suggest that the individual variation in Growth rates reflects variation in environments experienced during development or later life. An understanding of this variation may be essential for predicting the population dynamics of long-lived species under threat and identifying the most important environments to protect. This article is protected by copyright. All rights reserved.
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Indeterminate Growth in long-lived freshwater turtles as a component of individual fitness
Evolutionary Ecology, 2013Co-Authors: Justin D. Congdon, J. Whitfield Gibbons, Ronald J. Brooks, Njal Rollinson, Ria N. TsaliagosAbstract:Although evidence that reptiles exhibit Indeterminate Growth remains equivocal and based on inadequate data, the assumption that they do is still widely accepted as a general trait of reptiles. We examined patterns of variation in adult Growth using long-term mark-recapture data on 13 populations of 9 species representing 3 families of freshwater turtles located in South Carolina, Michigan, and Arizona in the USA and in Ontario, Canada. Across 13 study populations, Growth rates of all adults and only those that grew averaged 1.5 and 1.9 mm/yr respectively. Sources of variation in Growth rates included species, population, sex, age, and latitude. Most adults of both sexes with recapture intervals greater than 10 years grew, but across all populations an average of 19 % of individuals did not grow (some with recapture intervals up to 30 years). For known-age adults of three species, the highest Growth rates occurred during the 10 years following sexual maturity, and the proportions of non-growing individuals increased with age. Growth rates of adults were on average 92 % lower than those of juveniles. Based on linear relationships of clutch size and body size of females at average juvenile and adult Growth rates it would take 0.7 (0.2–1.2) years and 8.6 (min–max = 2.3–18.5) years, respectively, to grow enough to increase clutch size by one egg. The majority of within population variation in adult body size in 3 species appeared to be a combination of differences in ages at maturity and juvenile and early adult Growth, rather than Indeterminate Growth. The results from our study populations indicate that increases in body size (and associated reproductive output) that results from Indeterminate Growth are not substantial enough to represent a major factor in the evolution of life histories in general or the evolution of longevity and aging specifically.
Kirsty L. Nash - One of the best experts on this subject based on the ideXlab platform.
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Habitat structure and body size distributions: cross- ecosystem comparison for taxa with determinate and Indeterminate Growth
Oikos, 2014Co-Authors: Kirsty L. Nash, Craig R Allen, Shana M. Sundstrom, Chris Barichievy, Magnus Nyström, Nicholas A J GrahamAbstract:Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate Growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with Indeterminate Growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate Growth) and fish (Indeterminate Growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size-density relationships (SSDRs) and individual size-density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat-size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate Growth, such as birds. In contrast, for species with Indeterminate Growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.
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Habitat structure and body size distributions: cross‐ecosystem comparison for taxa with determinate and Indeterminate Growth
Oikos, 2014Co-Authors: Kirsty L. Nash, Craig R Allen, Shana M. Sundstrom, Chris Barichievy, Magnus Nyström, Nicholas A J GrahamAbstract:Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate Growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with Indeterminate Growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate Growth) and fish (Indeterminate Growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size-density relationships (SSDRs) and individual size-density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat-size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate Growth, such as birds. In contrast, for species with Indeterminate Growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.
Marco Festa-bianchet - One of the best experts on this subject based on the ideXlab platform.
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Tall young females get ahead: size-specific fecundity in wild kangaroos suggests a steep trade-off with Growth.
Oecologia, 2017Co-Authors: Louise Quesnel, Graeme Coulson, Wendy J. King, Marco Festa-bianchetAbstract:When resources are limited, organisms face allocation conflicts. Indeterminate Growth creates a persistent conflict with reproduction, as Growth may enhance future reproduction, but diverts resources from current reproduction. Little is known about allocation trade-offs in mammals with Indeterminate Growth. We studied Growth and reproduction in adult female eastern grey kangaroos (Macropus giganteus), an iteroparous mammal with Indeterminate Growth. Allocation trajectories varied with age and size: for 4-year-old females, fecundity increased from 30 to 82% from shortest to average-sized individuals. Older females had high fecundity regardless of size. The smallest females grew 30% more annually than average-sized females, but females that reached average size at an older age had lower Growth rates. Environmental conditions affected allocation to size and reproduction. Rainy springs increased fecundity from 61 to 84% for females that had previously reproduced, but rainy winters reduced leg Growth. Females in better relative condition grew 40% more than average, whereas most young of females below average relative condition failed to survive to 10 months of age. These results highlight an age-specific trade-off between Growth and reproduction. Tall young females benefit from a smaller trade-off between somatic Growth and early fecundity than shorter females of the same age, but older females appear to favor reproduction over Growth regardless of size. Our study highlights how individual heterogeneity determines trade-offs between life-history components. We speculate that cohort effects affect age-specific reproductive success in this long-lived mammal.
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Individual heterogeneity and offspring sex affect the Growth-reproduction trade-off in a mammal with Indeterminate Growth
Oecologia, 2016Co-Authors: Uriel Gelin, Michelle E. Wilson, Jemma Cripps, Graeme Coulson, Marco Festa-bianchetAbstract:Reproduction can lead to a trade-off with Growth, particularly when individuals reproduce before completing body Growth. Kangaroos have Indeterminate Growth and may always face this trade-off. We combined an experimental manipulation of reproductive effort and multi-year monitoring of a large sample size of marked individuals in two populations of eastern grey kangaroos to test the predictions (1) that reproduction decreases skeletal Growth and mass gain and (2) that mass loss leads to reproductive failure. We also tested if sex-allocation strategies influenced these trade-offs. Experimental reproductive suppression revealed negative effects of reproduction on mass gain and leg Growth from 1 year to the next. Unmanipulated females, however, showed a positive correlation between number of days lactating and leg Growth over periods of 2 years and longer, suggesting that over the long term, reproductive costs were masked by individual heterogeneity in resource acquisition. Mass gain was necessary for reproductive success the subsequent year. Although mothers of daughters generally lost more mass than females nursing sons, mothers in poor condition experienced greater mass gain and arm Growth if they had daughters than if they had sons. The strong links between individual mass changes and reproduction suggest that reproductive tactics are strongly resource-dependent.
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Individual heterogeneity and offspring sex affect the Growth- reproduction trade‑off in a mammal with Indeterminate Growth
Oecologia, 2015Co-Authors: Uriel Gelin, Michelle E. Wilson, Graeme Coulson, Jemma K. Cripps, Marco Festa-bianchetAbstract:Reproduction can lead to a trade-off with Growth, particularly when individuals reproduce before completing body Growth. Kangaroos have Indeterminate Growth and may always face this trade-off. We combined an experimental manipulation of reproductive effort and multi-year monitoring of a large sample size of marked individuals in two populations of eastern grey kangaroos to test the predictions (1) that reproduction decreases skeletal Growth and mass gain and (2) that mass loss leads to reproductive failure. We also tested if sex-allocation strategies influenced these trade-offs. Experimental reproductive suppression revealed negative effects of reproduction on mass gain and leg Growth from 1 year to the next. Unmanipulated females, however, showed a positive correlation between number of days lactating and leg Growth over periods of 2 years and longer, suggesting that over the long term, reproductive costs were masked by individual heterogeneity in resource acquisition. Mass gain was necessary for reproductive success the subsequent year. Although mothers of daughters generally lost more mass than females nursing sons, mothers in poor condition experienced greater mass gain and arm Growth if they had daughters than if they had sons. The strong links between individual mass changes and reproduction suggest that reproductive tactics are strongly resource-dependent.
Craig R Allen - One of the best experts on this subject based on the ideXlab platform.
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Habitat structure and body size distributions: cross- ecosystem comparison for taxa with determinate and Indeterminate Growth
Oikos, 2014Co-Authors: Kirsty L. Nash, Craig R Allen, Shana M. Sundstrom, Chris Barichievy, Magnus Nyström, Nicholas A J GrahamAbstract:Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate Growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with Indeterminate Growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate Growth) and fish (Indeterminate Growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size-density relationships (SSDRs) and individual size-density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat-size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate Growth, such as birds. In contrast, for species with Indeterminate Growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.
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Habitat structure and body size distributions: cross‐ecosystem comparison for taxa with determinate and Indeterminate Growth
Oikos, 2014Co-Authors: Kirsty L. Nash, Craig R Allen, Shana M. Sundstrom, Chris Barichievy, Magnus Nyström, Nicholas A J GrahamAbstract:Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate Growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with Indeterminate Growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate Growth) and fish (Indeterminate Growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size-density relationships (SSDRs) and individual size-density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat-size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate Growth, such as birds. In contrast, for species with Indeterminate Growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.
