A genetic mechanism for the evolution of senescence in Callosobruchus chinensis (the azuki bean weevil)

Tanaka, Yoshinari

doi:10.1038/hdy.1993.46

Cited by 30 publications

(23 citation statements)

References 24 publications

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“…These values are comparable to estimates found in other studies of C. maculatus (Mller et al, 1989), other species of seed beetles (Nomura and Yonezawa, 1990;Tuciae et al, 1991;Tanaka, 1993), other species of insects (Roff, 1992), and humans (Christiansen and Vaupel, 1996) but generally higher than observed in Drosophila (eg, Curtsinger et al, 1995;Promislow et al, 1996; but see Hughes, 1995). However, for senescence to evolve in response to natural selection, there must be genetic variation in the shape of the mortality curve, and not just in the mean lifespan.…”

Section: Evolutionary Genetics Of Lifespan and Mortality Ratessupporting

confidence: 74%

Evolutionary genetics of lifespan and mortality rates in two populations of the seed beetle, Callosobruchus maculatus

et al. 2004

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The age at which individuals die varies substantially within and between species, but we still have little understanding of why there is such variation in life expectancy. We examined sex-specific and genetic variation in adult lifespan and the shape of mortality curves both within and between two populations of the seed beetle, Callosobruchus maculatus, that differ in a suite of life history characters associated with adaptation to different host species. Mean adult lifespan and the shape of the logistic mortality curves differed substantially between males and females (males had lower initial mortality rates, but a faster increase in the rate of mortality with increasing age) and between populations (they differed in the rate of increase in mortality with age). Larger individuals lived longer than smaller individuals, both because they had lower initial mortality rates and a slower increase in the rate of mortality with increasing age. However, differences in body size were not adequate to explain the differences in mortality between the sexes or populations. Both lifespan and mortality rates were genetically variable within populations and genetic variance/ covariance matrices for lifespan differed between the populations and sexes. This study thus demonstrated substantial genetic variation in lifespan and mortality rates within and between populations of C. maculatus.

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Section: Evolutionary Genetics Of Lifespan and Mortality Ratessupporting

confidence: 74%

Evolutionary genetics of lifespan and mortality rates in two populations of the seed beetle, Callosobruchus maculatus

et al. 2004

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“…These estimates all fall in the range of estimates obtained in studies of male D. melanogaster (Swindell and Bouzat 2006). However, contrary to many previous studies with Drosophila (Snoke and Promislow 2003;Swindell and Bouzat 2006), although the inbreeding load for loci affecting mortality fluctuated with age we did not find that inbreeding load consistently increased with age, a result inconsistent with one prediction of mutationaccumulation theory (Charlesworth and Hughes 1996;Hughes et al 2002;Hughes and Reynolds 2005) but consistent with a previous study of another species of Callosobruchus (C. chinensis) that found no effect of female age on the magnitude of inbreeding depression on fecundity (Tanaka 1990(Tanaka , 1993. Our result that inbreeding load for the mortality rate does not increase with age initially appears inconsistent with the observed effect of inbreeding on the slope of the mortality curve-inbred females had significantly higher initial slopes (i.e., the mortality rate increased more quickly with age) than did outbred females.…”

Section: Discussioncontrasting

confidence: 56%

“…Inbreeding does not affect adult body size of either sex of S. limbatus but has been shown to affect female body size in C. maculatus (Tran and Credland 1995). Inbreeding also negatively affects female fecundity in both C. maculatus (Tran and Credland 1995) and its congener C. chinensis (Tanaka 1990(Tanaka , 1993, although there is no evidence that the effect of inbreeding on fecundity increases with age.…”

Section: Methodsmentioning

confidence: 70%

The Genetic Architecture of Life Span and Mortality Rates: Gender and Species Differences in Inbreeding Load of Two Seed-Feeding Beetles

et al. 2006

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We examine the inbreeding load for adult life span and mortality rates of two seed beetle species, Callosobruchus maculatus and Stator limbatus. Inbreeding load differs substantially between males and females in both study populations of C. maculatus-life span of inbred females was 9-13% shorter than the life span of outbred females, whereas the life span of inbred males did not differ from the life span of outbred males. The effect of inbreeding on female life span was largely due to an increase in the slope of the mortality curve. In contrast, inbreeding had only a small effect on the life span of S. limbatus-life spans of inbred beetles were $5% shorter than those of outbred beetles, and there was no difference in inbreeding load between the sexes. The inbreeding load for mean life span was $0.4-0.6 lethal equivalents per haploid gamete for female C. maculatus and $0.2-0.3 for both males and females of S. limbatus, all within the range of estimates commonly obtained for Drosophila. However, contrary to the predictions of mutation-accumulation models, inbreeding load for loci affecting mortality rates did not increase with age in either species, despite an effect of inbreeding on the initial rate of increase in mortality. This was because mortality rates decelerated with age and converged to a mortality plateau for both outbred and inbred beetles.T HE evolution of life span, mortality rates, and patterns of senescence is of substantial interest because there is tremendous variation in these traits at all taxonomic levels (Promislow 1991) and because of the medical implications of understanding the genetics underlying mortality rates. Studies on mice, Drosophila, and Caenorhabditis elegans have identified numerous genes that influence life span and/or rates of senescence (Harshman 2002). Recent studies of life span in Drosophila melanogaster indicate that inheritance of life span can be quite complex, with both dominance and epistasis having significant effects on variation in life span (Harshman 2002;Leips and Mackay 2002;Mackay 2002;Spencer et al. 2003;Spencer and Promislow 2005). These studies also show that the genetic architecture (number of genes and degree of allelic and genic interactions) underlying life span differs between the sexes and depends on the environmental conditions in which individuals are reared.One of the major genetic mechanisms proposed to underlie senescence is the accumulation in populations of late-acting deleterious alleles due to the declining force of selection with increasing age (mutation-accumulation theory) (Hughes and Reynolds 2005). Research has now identified many genes and chromosomal regions (QTL) that affect life span in model organisms but we have few data on the frequency of deleterious alleles affecting life span (De Luca et al. 2003;Carbone et al. 2006). We have less data on the sources of variation in deleterious alleles and the age specificity of expression of those alleles and thus their effects on age-specific mortality rates.Inbreeding studies are a com...

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“…While increases in inbreeding depression over the life span may also be subject to statistical challenges (Promislow and Tatar 1998;Promislow et al 1999), most are effectively circumvented by the methods used in the present analysis. In previous studies, researchers have tested for an increasing trend in sequential point estimates of inbreeding depression obtained throughout the life span (Tanaka 1993;Charlesworth and Hughes 1996;Hughes et al 2002;Snoke and Promislow 2003). A problem with this discrete approach is that sampling variances differ among the point estimates.…”

Section: Discussionmentioning

confidence: 99%

“…Alternatively, under the antagonistic pleiotropy theory of senescence, deleterious aging genes may be selected for because of beneficial pleiotropic effects early in the life span (Williams 1957). These two hypotheses make different predictions regarding how inbreeding should affect age-specific mortality (Tanaka 1993;Charlesworth and Hughes 1996). Under the mutationaccumulation hypothesis, the inbreeding load is inversely related to the sensitivity of fitness to trait values (Charlesworth and Hughes 1996), such that inbreeding depression for survivorship and all other fitness characters is expected to become increasingly severe at advanced ages (when the sensitivity of fitness to trait values declines).…”

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confidence: 99%

Inbreeding Depression and Male Survivorship in Drosophila: Implications for Senescence Theory

Swindell

Bouzat

2006

Genetics

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The extent to which inbreeding depression affects longevity and patterns of survivorship is an important issue from several research perspectives, including evolutionary biology, conservation biology, and the genetic analysis of quantitative traits. However, few previous inbreeding depression studies have considered longevity as a focal life-history trait. We maintained laboratory populations of Drosophila melanogaster at census population sizes of 2 and 10 male-female pairs for up to 66 generations and performed repeated assays of male survivorship throughout this time period. On average, significant levels of inbreeding depression were observed for median life span and age-specific mortality. For age-specific mortality, the severity of inbreeding depression increased over the life span. We found that a baseline inbreeding load of 0.307 lethal equivalents per gamete affected age-specific mortality, and that this value increased at a rate of 0.046 per day of the life span. With respect to some survivorship parameters, the differentiation of lineages was nonlinear with respect to the inbreeding coefficient, which suggested that nonadditive genetic variation contributed to variation among lineages. These findings provide insights into the genetic basis of longevity as a quantitative trait and have implications regarding the mutationaccumulation evolutionary explanation of senescence. I NBREEDING depression is the loss of fitness that has often been observed within progeny produced by the mating of closely related individuals (Lynch and Walsh 1998). This phenomenon has been a continuing research interest in evolutionary biology, conservation biology, and the genetic analysis of quantitative traits (Lande and

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A genetic mechanism for the evolution of senescence in Callosobruchus chinensis (the azuki bean weevil)

Cited by 30 publications

References 24 publications

Evolutionary genetics of lifespan and mortality rates in two populations of the seed beetle, Callosobruchus maculatus

Evolutionary genetics of lifespan and mortality rates in two populations of the seed beetle, Callosobruchus maculatus

The Genetic Architecture of Life Span and Mortality Rates: Gender and Species Differences in Inbreeding Load of Two Seed-Feeding Beetles

Inbreeding Depression and Male Survivorship in Drosophila: Implications for Senescence Theory

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