Regulation of reproduction rate in terrestrial placental mammals

Abstract

Abstract Mechanisms of regulation of reproduction are studied in a limited number of mammalian species, but these studies are extremely important for the conservation of rare animals. This study is a review of the data on reproductive biology of over 120 mammalian species. Four hierarchical levels of regulation of reproduction rate in mammalian females are identified: regulation of the number of embryos, regulation of the oestrous cycle, regulation of the number of females participating in reproduction, and regulation of reproduction rate at the population level. This classification makes it possible to draw a number of conclusions: (1) the mechanisms of reproductive regulation may be similar in distant taxonomic groups; (2) completely different regulatory mechanisms can be realized simultaneously in the same species at various levels; (3) the higher the level of regulation, the greater the number of individuals participating; (4) the nutritional factor is of integral importance and affects reproduction rate at all levels; (5) at the population level, the mechanism of anticipatory reproduction evolves, being a natural regulatory mechanism. The studies of reproductive restrictions in males may appear as a fruitful area for obtaining new data about regulation of reproduction rate in populations. The role of male reproductive activity in the regulation of reproduction seems highly underestimated.