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Evolution of sociality and parental care in bees of the genus Ceratina
Mikát, Michael ; Straka, Jakub (advisor) ; Schwarz, Michael (referee) ; Bogusch, Petr (referee)
Small carpenter bees (genus Ceratina) are an excellent model taxon for the study of evolution of parental care and origin of eusociality. Prolonged offspring care is typical for this bee genus. Females usually guard their offspring until adulthood and later feed their adult offspring pollen and nectar. Moreover, most of studied species are facultatively eusocial, a trait probably inherited from the common ancestor of the genus. Although Ceratina bees have generally very interesting behavior, detailed studies were performed in only a few species, usually from North America, Japan and Australia. Only anecdotal observations of natural history existed for a few European species, and detailed research has not been performed before my thesis. The goal of my thesis is to explore the natural history of European species of Ceratina and to identify possible costs and benefits of this species' behavioral traits. I focused on following these behavioral traits: social nesting, guarding of offspring until adulthood, and feeding of mature offspring. Through my master project, I discovered biparental care in species C. nigrolabiata, therefore the most important goal of my Ph.D. project is the evaluation of costs and benefits of this behavior. Guarding of offspring by mother significantly influences their survival,...
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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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Differences in behavior and sociability depending on environmental enrichment in a rat model of autism
Tučková, Klára ; Petrásek, Tomáš (advisor) ; Svoboda, Jan (referee)
Autism spectrum disorders are among the most severe congenital neurodevelopmental disorders. Even though many known risk factors can induce ASD, the exact etiology is not known. This thesis focuses on different approaches to studying ASD in rodent models. The main goal of the experimental part of the thesis was to examine the manifestations of ASD in a rat genetic model of tuberous sclerosis (so-called Eker rat) and to determine the effect of different housing environments on autistic phenotype. The animals were studied for one year. We performed three series of behavioral tests at the age of 45, 90 and 365 days. Testing was focused on assessment of exploration, anxiety, and sociality. Our results showed that the activity in the open field was higher in young Eker rats. The anxiety displayed in the elevated plus maze was reduced in rats kept in an enriched environment. In social interaction, the enriched environment significantly increased self-grooming. We observed less complex self-grooming in Eker rats housed without environmental enrichment. Ultrasound communication varied significantly with age. We confirmed that the enriched environment had a significant effect on the behavior of rats, but we observed no strong differences in behavior caused by the Eker genotype. Key words: autism, Eker,...
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The influence of selected environmental and behavioral factors on the degree of sociality in the family Herpestidae
Poláková, Petra ; Landová, Eva (advisor) ; Mazoch, Vladimír (referee)
Sociality in mongooses (Heprestidae) is a frequently studied characteristic. It is not known which factors modulate the degree of sociality. There are hypotheses about influence of environmental factors (habitat openness, temperature, precipitation). In this thesis we tested the influence of these environmental factors, but we did not discover any relation. Yet we found a strong relation between versatility (ecological valence) and inhabited climate conditions. Sociality could be modified by reproductive parameters (adaptations in greater litter size, longer gestation period and longer lactation period). We discovered relations between sociality (number of individuals in a social group) and gestation period, sociality and lactation period and sociality and litter size. We used phylogenetical correlation and found that the relation between sociality and litter size is not significant. Greater litter size occurs in only one phylogenetical line; hence we consider greater litter size to be not a predisposition, but a result of transition to sociality. It is also not clear what is the ancestral state of sociality and used habitat on the base of the clade. Hypotheses say that the common ancestor of the mongooses was solitary and lived in a closed habitat, but based on our ancestral states reconstruction...
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Sociality and ecology in ground squirrels (tribe Marmotini).
Matějů, Jan
of the Ph.D. thesis Autor: Jan Matějů Name: Sociality and ecology in ground squirrels (tribe Marmotini) Ground-dwelling squirrels are parafyletic group of rodents from the family Sciuridae (tribes Marmotini and Xerini). Ground-dwelling squirrels are semi-fossorial inhabitants of treeless biotopes. They share most aspects of general biology. They usually breed once a year, have exclusively diurnal activity and are omnivorous. On the contrary, ground-dwelling squirrels display different levels of sociality, which makes them an ideal model to study different ecological aspects connected with evolution of sociality. The first part of the Ph.D. thesis is focused on the relationship between sociality and sexual size dimorphism and relative and absolute size of brain. At first, supposing that different levels of sociality are connected with differences in intensity of sexual selection acting on males, we tested association between sociality and sexual size dimorphism as well as association between sexual size dimorphism and body size - so called Rensch rule. Next, we tested correlation between sociality and relative brain size. In agreement with the Social brain hypothesis, we assumed that e.g. solitarily living species should have smaller relative brain size than species living in stable pairs. We found...
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Parental care and sociality in family Halictidae (Anthophila)
Vinická, Eliška ; Straka, Jakub (advisor) ; Klimeš, Petr (referee)
Halictidae is an important family of bees interesting mainly for the diversification of social organisation of individual species. Their sociality ranges from solitary individuals who live and care for their offspring themselves, through species that build common nests, to eusocial colonies in which the reproductive division of labour has developed. Exploring such diversity among closely related species may contribute to understanding the evolution of sociality. Thus, we can observe the development of social organization up to its higher levels, such as eusociality, or conversely, gradual evolutionary regression to solitary individuals. For such research, however, it is necessary to know not only the phylogenetic development but especially a detailed description of social behaviour in individual species. However, there are few such studies. Some of them are summarized in this work.
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Evolution of sociality and parental care in bees of the genus Ceratina
Mikát, Michael ; Straka, Jakub (advisor) ; Schwarz, Michael (referee) ; Bogusch, Petr (referee)
Small carpenter bees (genus Ceratina) are an excellent model taxon for the study of evolution of parental care and origin of eusociality. Prolonged offspring care is typical for this bee genus. Females usually guard their offspring until adulthood and later feed their adult offspring pollen and nectar. Moreover, most of studied species are facultatively eusocial, a trait probably inherited from the common ancestor of the genus. Although Ceratina bees have generally very interesting behavior, detailed studies were performed in only a few species, usually from North America, Japan and Australia. Only anecdotal observations of natural history existed for a few European species, and detailed research has not been performed before my thesis. The goal of my thesis is to explore the natural history of European species of Ceratina and to identify possible costs and benefits of this species' behavioral traits. I focused on following these behavioral traits: social nesting, guarding of offspring until adulthood, and feeding of mature offspring. Through my master project, I discovered biparental care in species C. nigrolabiata, therefore the most important goal of my Ph.D. project is the evaluation of costs and benefits of this behavior. Guarding of offspring by mother significantly influences their survival,...
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Social Brain Hypothesis: A Survey of Evidence
Kverková, Kristina ; Němec, Pavel (advisor) ; Pavelková, Věra (referee)
The social brain hypothesis was first proposed to explain the remarkable cognitive abilities of primates and has since been extended to other taxa. Generally, it posits that sociality is a major selection pressure driving the evolution of large brains and intelligence. However, there is no single version of the hypothesis and different underlying mechanisms have been proposed. Tests of the hypothesis rely on appropriate indices of social complexity and brain size, as a proxy for cognitive abilities, and difficulties are associated with choosing both these variables and obtaining precise data. Situation is further complicated by that fact that a multitude of factors potentially contributing to or constraining encephalization is highly intercorrelated. This bachelor's thesis reviews approaches to research in this field and presents a survey of relevant evidence accumulated so far. The social brain hypothesis has been tested in various ways in primates, carnivores, ungulates, cetaceans, insectivores, bats, birds, fish (cichlids), and insects. The jury is still out, since contrasting results exist for most of these groups, warranting more research to help elucidate the influence of sociality on brain evolution.
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Sociality and ecology in ground squirrels (tribe Marmotini).
Matějů, Jan
of the Ph.D. thesis Autor: Jan Matějů Name: Sociality and ecology in ground squirrels (tribe Marmotini) Ground-dwelling squirrels are parafyletic group of rodents from the family Sciuridae (tribes Marmotini and Xerini). Ground-dwelling squirrels are semi-fossorial inhabitants of treeless biotopes. They share most aspects of general biology. They usually breed once a year, have exclusively diurnal activity and are omnivorous. On the contrary, ground-dwelling squirrels display different levels of sociality, which makes them an ideal model to study different ecological aspects connected with evolution of sociality. The first part of the Ph.D. thesis is focused on the relationship between sociality and sexual size dimorphism and relative and absolute size of brain. At first, supposing that different levels of sociality are connected with differences in intensity of sexual selection acting on males, we tested association between sociality and sexual size dimorphism as well as association between sexual size dimorphism and body size - so called Rensch rule. Next, we tested correlation between sociality and relative brain size. In agreement with the Social brain hypothesis, we assumed that e.g. solitarily living species should have smaller relative brain size than species living in stable pairs. We found...
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The influence of selected environmental and behavioral factors on the degree of sociality in the family Herpestidae
Poláková, Petra ; Landová, Eva (advisor) ; Mazoch, Vladimír (referee)
Sociality in mongooses (Heprestidae) is a frequently studied characteristic. It is not known which factors modulate the degree of sociality. There are hypotheses about influence of environmental factors (habitat openness, temperature, precipitation). In this thesis we tested the influence of these environmental factors, but we did not discover any relation. Yet we found a strong relation between versatility (ecological valence) and inhabited climate conditions. Sociality could be modified by reproductive parameters (adaptations in greater litter size, longer gestation period and longer lactation period). We discovered relations between sociality (number of individuals in a social group) and gestation period, sociality and lactation period and sociality and litter size. We used phylogenetical correlation and found that the relation between sociality and litter size is not significant. Greater litter size occurs in only one phylogenetical line; hence we consider greater litter size to be not a predisposition, but a result of transition to sociality. It is also not clear what is the ancestral state of sociality and used habitat on the base of the clade. Hypotheses say that the common ancestor of the mongooses was solitary and lived in a closed habitat, but based on our ancestral states reconstruction...
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