Life-Table Comparisons between Two Ground Squirrels

We present a comparative test of Charnov's recent theoretical model of mammalian life‐history evolution. Phylogenetic analysis of life‐table data from 64 species, ranging across nine orders. supports all of Charnov's assumptions and most of his predictions. The allometries of time from independence to maturity (a), annual fecundity, and adult and juvenile mortality rates are in agreement with previous work and with the theory, as are the signs of the relationships among these traits when body size is controlled for. As predicted, the non‐dimensional products of a and each of the other three traits are independent of adult body size, as is survivorship to maturity. However, we find that the ratio of weaning weight to adult weight (δ) is correlated with adult weight, in contradiction with the theory, and we do not find the predicted relationships between δ and the three non‐dimensional products. The discrepancies could be because we have equated independence with weaning, or because the model assumes determinate growth: they could arise if large mammals have relatively longer periods of post‐weaning care, or continue to grow after starting to reproduce. There is some evidence that δ is influenced by the nature of mortality around independence (density‐dependent or density‐independent), and we suggest this as a possible area for further work. In general, the areas of agreement between Charnov's theory and the data are more impressive than the differences, indicating that it could be a major breakthrough in understanding the evolution of life histories in placental mammals.

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“…Population size is constant, so we assumed Ro = 1 to estimate no from fecundity data. Luo & Fox (1990). Bronson (1979).…”

Section: Discussionmentioning

confidence: 99%

Mammal life‐history evolution: a comparative test of Charnov's model

1995

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“…A.2. The sensitivity of to changes in P j is: When organisms in the first age class reproduce (e.g., Slade and Balph 1974, Sherman and Morton 1984, Zammuto 1987, Luo and Fox 1990, Cully 1997, ␣ equals 1 and Eq. A.3 becomes: Thus, when organisms in the first age class reproduce, the sensitivity of to changes in P j calculated from the Caswell-Slade model is zero.…”

Section: Discussionmentioning

confidence: 99%

Partial Life-Cycle Analysis: A Model for Birth-Pulse Populations

Oli

Zinner

2001

Ecology

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Matrix population models have become standard tools for the demographic analysis of age-or stage-structured populations. Although age-classified (Leslie) matrix models make maximum use of age-specific demographic data, age at first reproduction, which has been suggested to be an important life-history variable, does not appear as an explicit parameter in these models. Consequently, the sensitivity of population growth rate to changes in age at first reproduction cannot be calculated using standard techniques. Agespecific demographic data to parameterize age-structured models are difficult to collect, and models that can be parameterized with partial demographic data (''partial life-cycle models'') have been developed. Partial life-cycle models are based on life-history stages, and these models can also be used to calculate sensitivity of population growth rate to changes in various life-history variables, including ages at first and last reproduction. Here, we present a partial life-cycle model appropriate for situations where demographic data are collected immediately after the birth pulse (post-breeding census). We present methods of parameterizing the partial life-cycle model, and derive formulas for calculating the sensitivity of the population growth rate to changes in model parameters, including ages at first and last reproduction. We analyzed life-table data for several species of mammals using the partial life-cycle model and found that results of our partial life-cycle model compare favorably with those obtained from the corresponding age-classified models.

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“…The rest of this article is organized as follows: in Section 2, we explain how to compute the kinship matrices directly from the projection matrix of the population. We then illustrate the method in Section 3 using the life-cycle of the ground squirrel Spermophilus dauricus from Luo and Fox (1990); other detailed examples of applications can be found in SM.2. Finally, we conclude by discussing the limitations, implications and possible extensions of our method in Section 4.…”

Section: The Kinship Matricesmentioning

confidence: 99%

“…Using the life table for the ground squirrel Spermophilus dauricus from Luo and Fox (1990), we get the following survival and fertility matrices: For instance, the (3,2)-th entry of P S shows that, at the demographic steady state, 54% of class-3 individuals were in class 2 the previous year. Similarly, the (1, 1)-th entry of P F indicates that a yearling has a 23% probability of having been born to a yearling the previous year.…”

Section: Illustrationmentioning

confidence: 99%

The Kinship Matrix: Inferring the Kinship Structure of a Population from its Demography

Coste¹,

Bienvenu

Ronget

et al. 2021

Preprint

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The familial structure of a population and the relatedness of its individuals are determined by its demography. There is, however, no general method to infer kinship directly from the life-cycle of a structured population. Yet this question is central to fields such as ecology, evolution and conservation, especially in contexts where there is a strong interdependence between familial structure and population dynamics. Here, we give a general formula to compute, from any matrix population model, the expected number of arbitrary kin (sisters, nieces, cousins, etc) of a focal individual ego, structured by the class of ego and of its kin. Central to our approach are classic but little-used tools known as genealogical matrices, which we combine in a new way. Our method can be used to obtain both individual-based and population-wide metrics of kinship, as we illustrate. It also makes it possible to analyze the sensitivity of the kinship structure to the traits implemented in the model.

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Life-Table Comparisons between Two Ground Squirrels

Cited by 11 publications

References 0 publications

Mammal life‐history evolution: a comparative test of Charnov's model

Mammal life‐history evolution: a comparative test of Charnov's model

Partial Life-Cycle Analysis: A Model for Birth-Pulse Populations

The Kinship Matrix: Inferring the Kinship Structure of a Population from its Demography

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