Mating Affects Lifespan Differently in Two Strains of Pseudo-female Caenorhabditis elegans

Ruben Lancaster

doi:10.5399/uo/ourj/17.1.4

Abstract

Mating is vital for sexually reproducing species, yet the ideal mating strategy for males and females can differ. The ensuing conflict between the sexes – namely, sexual conflict – results in a decrease in population level fitness. The degree of sexual conflict can be affected by the behavior, physiology, and life history of a population. Previous studies in the nematode Caenorhabditis elegans have shown that mating causes lifespan to decrease in pseudo-females and hermaphrodites, which was interpreted as evidence of sexual conflict. However, it is still an open question whether variations in mating condition and strain type can affect the degree of sexual conflict and lifespan decrease. Here, I investigate whether lifespan is affected by mating in conditions other than sex- skewed individual mating scenarios used in previous work. I conducted population-based mating assays in two different strains of C. elegans using both natural and male-skewed sex ratios. Counter to expectations, I found no effect of mating on lifespan in a wild isolate of C. elegans, while virgins from a canonical laboratory strain had a decreased lifespan relative to their counterparts mated in groups. My data offers a counterpoint to the literature, which agrees that mating universally decreases the lifespan of C. elegans pseudo-females and hermaphrodites. These results highlight the flexibility of reproductive costs and the importance of life histories in experimental populations.

Highlights

Males and females of the same species can have different optimal mating strategies
In N2fog-2, pseudo-females mated in groups of male-skewed ratios had significantly longer lifespans than virgin pseudo-females mated in both group (p < 0.001) and individual (p < 0.05 ) assays (Figure 3A)
The shape of the lifespan curves of N2fog-2 virgins is intriguing as they do not mimic the lifespan curve of mated worms, due to an abnormal linear decrease in cohort survivorship by day 20 (Figure 3A)

Summary

Introduction

Males and females of the same species can have different optimal mating strategies. For example, in fruit flies, males produce maximum offspring at high re-mating rates, limited by the number of females with which they can mate (Bateman, 1948; Fowler and Partridge, 1989). Females produce maximum offspring at intermediate mating rates, limited by the number of eggs they can lay (Fowler and Partridge, 1989) In another example, male beetles are known to damage female beetle reproductive tracts as a by-product of selection for traits that increase male fertilization success (Arnqvist and Rowe 2013; Hotzy et al, 2012; Morrow et al, 2003). The. Lancaster disparity between optimal reproductive phenotype and genotype, as well as the resulting negative effect on fitness, is called sexual conflict. Lancaster disparity between optimal reproductive phenotype and genotype, as well as the resulting negative effect on fitness, is called sexual conflict This means that an increase in mating success in one sex may not increase the reproductive output of the other sex

Methods

Results

Discussion

Conclusion