The Effect of Inbreeding on the Reproductive Rate of Yellow Steppe Lemmings (Eolagurus luteus, Rodentia, Cricetidae) in a Laboratory Colony.

Archive data were analyzed concerning the reproduction of yellow steppe lemmings (Eolagurus luteus) in the Moscow Zoo. We used information referring to E. luteus pairs that existed during two periods: 2008–2013 (first colony) and 2017–2020 (second colony). All breeding partners in the first colony had at least one common ancestor (they originated from two females and one male) and thus were closely related to each other. The degree of relatedness of partners in the second colony was much lower. The founders of that colony were five females and five males that had originated from four pairs of unrelated individuals live-trapped in the Zaisan Basin. We conducted a comparative assessment of the life expectancy and reproductive parameters of adult yellow steppe lemmings and the survival of their offspring in two colonies, that is, we observed the effect of different degrees of inbreeding on such parameters. We also assessed the effect of female age on those values. We assigned the females to two age categories: younger (age of 15–59 days by the time of pair establishment) and older (age of 60–701 days) category. The results of statistical analysis confirmed the significant influence of the degree of relatedness of partners on the proportion of reproducing females, the number of litters per pair, the number of survived pups per pair, the mean number of pups per litter, the inter-birth interval, the female life expectancy, and the period of pair existence. The influence of female age on these parameters was insignificant. Our data provide evidence for a pronounced inbreeding depression in the first captive colony of the yellow steppe lemming. [ABSTRACT FROM AUTHOR]