Gender Separation Increases Somatic Growth in Females but Does Not Affect Lifespan in Nothobranchius furzeri

Abstract

According to life history theory, physiological and ecological traits and parameters influence an individual's life history and thus, ultimately, its lifespan. Mating and reproduction are costly activities, and in a variety of model organisms, a negative correlation of longevity and reproductive effort has been demonstrated. We are employing the annual killifish Nothobranchius furzeri as a vertebrate model for ageing. N. furzeri is the vertebrate displaying the shortest known lifespan in captivity with particular strains living only three to four months under optimal laboratory conditions. The animals show explosive growth, early sexual maturation and age-dependent physiological and behavioural decline. Here, we have used N. furzeri to investigate a potential reproduction-longevity trade-off in both sexes by means of gender separation. Though female reproductive effort and offspring investment were significantly reduced after separation, as investigated by analysis of clutch size, eggs in the ovaries and ovary mass, the energetic surplus was not reallocated towards somatic maintenance. In fact, a significant extension of lifespan could not be observed in either sex. This is despite the fact that separated females, but not males, grew significantly larger and heavier than the respective controls. Therefore, it remains elusive whether lifespan of an annual species evolved in periodically vanishing habitats can be prolonged on the cost of reproduction at all.

Histone deacetylase 1 expression is inversely correlated with age in the short-lived fish Nothobranchius furzeri

“…3a). Lifespan analysis of the MZM N. furzeri strain conducted in our fish facility compares well with reports from other laboratories (Graf et al 2010). To correlate the survival rate with class I Hdac expression levels, we performed western blotting of whole killifish protein extracts in an age-dependent time course (Fig.…”

Squeezing out the last egg—annual fish increase reproductive efforts in response to a predation threat

“…Yet, no such trade‐off was found between exposed and control females, as fish in both treatments died at the same rates. This contradicts earlier findings on N. wattersi that were exposed to cues that signal desiccation risk (Grégoir et al., 2017), but is in line with the results of previous studies on N. furzeri , where female egg deposition was shown to decrease in the absence of males (Graf, Cellerino, & Englert, 2010). As to why such differences are found between studies remains unclear.…”

Alternative intrapopulation life‐history strategies and their trade‐offs in an African annual fish

“…After the final experimental spawning at the age of 63 days, females had no access to males and did not spawn. Given previous reports of spontaneous egg deposition in the absence of males under comparable experimental conditions (Graf et al ., ), the failure of spontaneous egg deposition was not anticipated under our experimental conditions. However, most females were not capable of releasing all their eggs in the absence of males.…”

“…This outcome was not anticipated as Graf et al . () reported no physiological defect in females kept in the absence of males in N. furzeri . It is also notable that due to the higher mortality of males and incidences of extremely female‐biased sex ratios (> 90% of females) in the wild (Reichard et al ., ), the lack of males may be relevant at the end of the rainy season.…”

“…We recorded the date of natural death for each experimental individual. Unexpectedly, most experimental females likely died due to a failure to lay eggs in the absence of males (compare Graf et al ., ; see for more details). Consequently, differences in survival and lifespan were only tested in males.…”