Fitness differences between parthenogenetic litters of the parthenogenetic scorpion Tityus stigmurus

 

We often think that parthenogenetic reproduction produces clones that are identical in most ways. But there are non-genetical factors that may cause variations even though the organism is living in the same, stable environment. One example of this is maternal age's impact on different parthenogenetic litters.

Welton Dionisio-da-Silva and co-workers have recently pulished a study on non-Mendelian variation on parthenogenetic litters in the medical important species Tityus stigmurus (Thorell, 1876) (Buthidae). Their results indicate that T. stigmurus females allocated nutrient resources to maximize litter size rather than developmental fitness in subsequent litters. See abstract and article for more details.

I can add that knowledge of reproduction and life history of this scorpion is important as it is a medical important species that thrive in urban areas with high risk of human contact. 

Abstract:
Clonal lineages in similar environments may be influenced by non-Mendelian inheritance, such as maternal age effects and developmental instabilities. These mechanisms may affect the developmental fitness of parthenogenetic litters. In this study, the scorpion Tityus stigmurus (Thorell, 1876) was used to analyze the effects of non-Mendelian variation on parthenogenetic litters. A total of 75 juveniles from five females were reared under the same controlled conditions, while their development was observed and evaluated through differences in offspring fitness traits (litter size, prosoma size, developmental time, and mortality) between the litters. First and second litters had a similar litter size, although second litters exhibited longer developmental time in the early instar stages (second and third) than first litters. These results indicate that T. stigmurus females allocated nutrient resources to maximize litter size rather than developmental fitness in subsequent litters. Differences in developmental time found in early instars but not in late instars may have occurred as a result of stochastic developmental variations in young individuals. Such variation in duration of development has the potential to influence survival of juveniles in natural environments because individuals that grow faster may avoid large predators and consume larger prey, compared to those that do not.

Reference:
Dionisio-da-Silva W, Albuquerque CMR, Lira AFA. Fitness differences between parthenogenetic litters of the synanthropic scorpion Tityus stigmurus (Scorpiones: Buthidae). Animal Biology. 2022;72:435-46. [Subscription required for full text]

Thanks to Welton Dionisio-da-Silva for sending me their article!