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Evolution of litter size in hystricomorph rodents
Cingelová, Alexandra ; Dušek, Adam (advisor) ; Špoutil, František (referee)
The suborder Hystricomorpha is an ideal model group for the study of rodent life-history evolution due to its wide distribution, great diversity of inhabited ecosystems and social systems. By tracking several factors, it was possible to determine the key factors that influenced litter size during evolution. The data set contained 75 of the total 292 species of the suborder. The average litter size, female and male body size, level of sexual dimorphism, level of sociality, type of reproductive system, level of parental care, presence of multipaternity, type of habitat and food were assigned to each species based on the information obtained from the available literature. The analysis included a statistical part calculated using general linear mixed models, and a phylogenetic part including parsimonious mapping of characters onto the phylogenetic tree and linear regression using phylogenetic independent contrasts. Social factors like degree of sociality, sexual dimorphism and reproductive system significantly influenced litter size at birth. Multipaternity also had an influence, but less than the first three factors. Ecological factors, food and environment, had no effects unless they were combined with the effect of family. It is therefore possible to assume that ecological factors have influenced...
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Optimization of litter size in rodents
Cingelová, Alexandra ; Dušek, Adam (advisor) ; Sedláček, František (referee)
Optimization of litter size can be defined as adjustment of litter size according to actual environmental conditions or condition of mother to reach a compromise between the maximum number of offspring and their individual fitness. Rodents are an ideal taxon to study this topic because of their enormous interspecific variability in life strategies across the whole order. The variation in litter size among rodent species was influenced by countless ecological and social factors during their evolution. These include the geographical location of the breeding populations, various life and reproductive strategies such as r-/K-strategy, the presence of altricial or precocious offspring, various ways of life, the presence of water in the environment, predation rate, hibernation, and sociality. Litter size can be adjusted already before fertilization, for example by choosing a partner, by timing reproduction, condition, age and social status of the mother. Genetic factors affecting litter size are, for example, MHC glycoprotein polymorphism and t-haplotype. Reduction of the litter size may occur before insemination by influencing the ovulation rate, female reproductive hormone levels and exposure to the stressors, during implantation by selective abortion, and postpartum by infanticide, siblicide, and...
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Optimization of litter size in rodents
Cingelová, Alexandra ; Dušek, Adam (advisor) ; Sedláček, František (referee)
Optimization of litter size can be defined as adjustment of litter size according to actual environmental conditions or condition of mother to reach a compromise between the maximum number of offspring and their individual fitness. Rodents are an ideal taxon to study this topic because of their enormous interspecific variability in life strategies across the whole order. The variation in litter size among rodent species was influenced by countless ecological and social factors during their evolution. These include the geographical location of the breeding populations, various life and reproductive strategies such as r-/K-strategy, the presence of altricial or precocious offspring, various ways of life, the presence of water in the environment, predation rate, hibernation, and sociality. Litter size can be adjusted already before fertilization, for example by choosing a partner, by timing reproduction, condition, age and social status of the mother. Genetic factors affecting litter size are, for example, MHC glycoprotein polymorphism and t-haplotype. Reduction of the litter size may occur before insemination by influencing the ovulation rate, female reproductive hormone levels and exposure to the stressors, during implantation by selective abortion, and postpartum by infanticide, siblicide, and...
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