Most mammals are iteroparous, meaning they can undergo multiple cycles of reproduction and gradually advance in age. In stark contrast, semelparous species only reproduce once before they die, as the physiological toll of mating is quite high. Examples of semelparous species include Pacific salmon, which swim upstream where they die after spawning, thus becoming nutrients for their own offspring and the environment. By only 10 months of age, male kalutas are ready to mate. During a period of only two weeks, when environmental conditions are just right of course, they spend up to 14 hours at a time mating with multiple females then die from chronic stress and exhaustion.  

The nematode C. elegans is a unique organism that can exhibit wide variations in lifespan. Hermaphrodites are able to reproduce on their own. In the case of C. elegans, hermaphrodites do something really strange – they convert their gut into yolk that can be vented to feed their young. By doing so, they make the ultimate sacrifice for their offspring. The costs of reproduction similarly decrease the lifespan of females, although females are not known to produce yolk. When researchers removed the germline and ability for hermaphrodites and females to reproduce, their lifespan increased. Similar increases in lifespan are seen if the gonads of Pacific salmon are removed.  

Source:

CC Kern, S Srivastava, M Ezcurra, KC Hsiung, N Hui, S Townsend, D Maczik, B Zhang, V Tse, V Konstantellos, J Bähler, D Gems. C. elegans ageing is accelerated by a self-destructive reproductive programme. Nature Communications. 14: 4381, 2023

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Categories: Aging, Extreme Animals, Reproduction and Development, Stress

Tags: C. elegans, longevity, nature, science, semelparity, wildlife