Sex-specific effects of natural and sexual selection on the evolution of life span and ageing in Drosophila simulans
Archer, C.R. ; Duffy, E. ; Hosken, D.J. ; Mokkonen, M. ; Okada, K. ; Oku, K. ; Sharma, M.D. ; Hunt, J. - \ 2015
Functional Ecology 29 (2015)4. - ISSN 0269-8463 - p. 562 - 569.
extrinsic mortality - oxidative stress - female fitness - history traits - male-sterility - seed beetle - senescence - melanogaster - age - populations
1. Variation in the strength of age-dependent natural selection shapes differences in ageing rates across species and populations. Likewise, sexual selection can promote divergent patterns of senescence across the sexes. However, the effects of these processes on the evolution of ageing have largely been considered independently, and interactions between them are poorly understood. 2. We use experimental evolution to investigate how natural and sexual selection affect life span and ageing in Drosophila simulans. 3. Replicate populations were evolved under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and at one of two temperatures, 25 °C (relaxed natural selection) or 27 °C (enhanced natural selection), in a fully factorial design. We measured longevity in 150 individually housed flies taken from each of three replicate populations per selection regime. 4. We found that natural and sexual selection affected the evolution of life span via sex-specific effects on different ageing parameters (ageing rate vs. baseline mortality): natural selection reduced the rate of ageing in both sexes but increased male baseline mortality, while sexual selection elevated baseline mortality in both sexes but particularly in males. 5. This means that sexual and natural selection interacted to reduce male life span but acted on female life span by independently affecting particular ageing parameters. Sex-specific effects of sexual and natural selection may help explain the diverse patterns of ageing seen in nature but complicate predictions about how ageing and life span evolve across the sexes.
Genetic variation for stress-response hormesis in C. elegans lifespan
Rodriguez Sanchez, M. ; Snoek, L.B. ; Riksen, J.A.G. ; Bevers, R.P.J. ; Kammenga, J.E. - \ 2012
Experimental Gerontology 47 (2012)8. - ISSN 0531-5565 - p. 581 - 587.
quantitative trait loci - genotype-environment interactions - nematode caenorhabditis-elegans - long-lived mutant - drosophila-melanogaster - heat-shock - history traits - natural variation - longevity - resistance
Increased lifespan can be associated with greater resistance to many different stressors, most notably thermal stress. Such hormetic effects have also been found in C. elegans where short-term exposure to heat lengthens the lifespan. Genetic investigations have been carried out using mutation perturbations in a single genotype, the wild type Bristol N2. Yet, induced mutations do not yield insight regarding the natural genetic variation of thermal tolerance and lifespan. We investigated the genetic variation of heat-shock recovery, i.e. hormetic effects on lifespan and associated quantitative trait loci (QTL) in C. elegans. Heat-shock resulted in an 18% lifespan increase in wild type CB4856 whereas N2 did not show a lifespan elongation. Using recombinant inbred lines (RILs) derived from a cross between wild types N2 and CB4856 we found natural variation in stress-response hormesis in lifespan. Approx. 28% of the RILs displayed a hormesis effect in lifespan. We did not find any hormesis effects for total offspring. Across the RILs there was no relation between lifespan and offspring. The ability to recover from heat-shock mapped to a significant QTL on chromosome II which overlapped with a QTL for offspring under heat-shock conditions. The QTL was confirmed by introgressing relatively small CB4856 regions into chromosome II of N2. Our observations show that there is natural variation in hormetic effects on C. elegans lifespan for heat-shock and that this variation is genetically determined.