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Variation in human secondary sex ratio after extraordinary natural, social and cultural events
Hubová, Hana ; Kaňková, Šárka (advisor) ; Dušek, Adam (referee)
The secondary sex ratio represents the proportion of male and female births and is usually slightly skewed towards male births. Changes in the secondary sex ratio may be induced by a variety of ultimate (evolutionary) or proximate (physiological) causes. These causes tend to be linked to external factors such as natural disasters, armed conflicts, terrorism and/or important cultural and sports events. Natural disasters cause major destruction of housing, infrastructure and loss of lives. Such events are likely to be followed by a decrease in the secondary sex ratio. Stress-induced selection in utero against males is one of the widely discussed causes related to this phenomenon. Armed conflicts and terrorism commonly have a negative impact on society as well, however, an increase in the secondary sex ratio was often observed in the post-war periods. Important cultural and sports events, along with holiday celebrations, have a mostly positive impact on the social climate. These events induce a sense of community and are likely to be followed by an increase in the secondary sex ratio 9 months later, which suggests higher coital rates during such events.
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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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Demographic development in Cambodia since the second half of the 20th century
Dušek, Adam ; Hulíková Tesárková, Klára (advisor) ; Fialová, Ludmila (referee)
Demographic development in Cambodia since the second half of the 20th century Abstract This thesis deals with the population development in Cambodia since the second half of the 20th century. The objective of the thesis is to characterize population development in Cambodia during 1950-2020, focusing on the period of the 1970s. A sub-objective is to put demographic development into a historical context. The topic was analyzed through a study of relevant literature and subsequent demographic analysis based on data from the World Population Prospects database, other UN institutions and publications of notable scholars. It has been confirmed that the events that took place in the country during the Khmer Rouge rule from 1975 to 1979 had a significant impact on the population development and direction of the country. Extreme violence and harsh living conditions claimed at least 1.5 million victims. The age-sex structure was fundamentally distorted by the high excess mortality of young men. A period of increased fertility followed, but soon declined. Cambodia's population rose from 4.4 million to 16.7 million during the period under review. However, population growth has been slowing down due to declining fertility and high emigration. Keywords Cambodia, demographic development, Khmer Rouge, excess mortality
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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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Maternal Investment Strategy in Model Monotocous and Polytocous Mammals: A Life-History Perspective
Dušek, Adam
The litter size is one of the most important determinants of mammalian life-histories. Depending on the size of the litter, the mammals can be divided into two main groups: (1) the monotocous mammals, producing only one offspring per litter; and (2) the polytocous mammals, producing more than one offspring per litter. This life-history dichotomy entails different strategies whereby the mammalian females may optimize their maternal investment. The aim of this Ph.D. thesis is to show variation in the maternal investment strategies of monotocous and polytocous mammals from a life-history perspective. In order to address this issue, I investigated the strategy of maternal investment in the red deer (Cervus elaphus), representing a typical monotocous mammal, and the house mouse (Mus musculus), representing a typical polytocous mammal. From a life-history perspective, the red deer, producing no more than one litter per year, can be viewed as a model of "K-selected species", while the house mouse, producing up to ten litters per year, can be viewed as a model of "r- selected species". The red deer and the house mouse are ideal model organisms for this type of research also because they both are representatives of the most common mammalian mating system - the simultaneous polygyny. A general assumption of...
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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 delivery date in cervids
Schnebergerová, Adriana ; Dušek, Adam (advisor) ; Sedláček, František (referee)
Female mammals adjust their birth date according to actual environmental conditions and their own condition to maximize their reproductive fitness. Optimizing of birth date allows the mothers to maximize not only their own fitness but also the fitness of their offspring. The aim of my bachelor`s thesis is to document the optimization of the delivery date in the deer family (Cervidae), i.e. timing of delivery whereby females can attain successful reproduction. This family is thanks to world-wide areal an ideal taxon for the study of optimization of the delivery date. 40 species and 200 subspecies renders this family one of the most diversified and the most numerous of even-toed ungulates (Artiodactyla). In general, factors that affect the timing of the delivery date are: ecological, behavioral, reproductive, physiological and genetic. These factors include, for example, seasonality, availability and quality of food, condition, social rank and age of the female, the presence of the male and the sex of the offspring. Depending on actual environmental conditions, female deer may either hasten or, on the contrary, delay the delivery date and thus maximize the chances of survival of their offspring. The synchronization of the birth date is another important strategy which allows females to reduce the...
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Levels of physiologically active substances during the ontogeny of social hierarchy in two house mouse subspecies
Bufková Daniszová, Kristina ; Stopka, Pavel (advisor) ; Dušek, Adam (referee) ; Sedláček, František (referee)
2 Abstract Social interactions of animals are represented by a complex network of relations among individuals affected by many factors. From a practical point of view, it is very complicated or even impossible to observe these interactions under natural conditions and consider all fundamental underlying factors. A suitable solution may be, for example, to use a social environment of so called fraternal pairs. With a simplified model represented by pairs of brothers it is possible - given a properly set length of the experiment and age of the individuals involved in it - to reveal various aspects of establishing social hierarchies. A key factor influencing an individual's position (especially of a male) in the group is considered to be his physical fitness which is usually connected with his size and hence with his body mass. In addition to physical qualities of individuals, a fundamental role for achieving the "social" success is also played by the ability to communicate these qualities (e.g. through chemical signals) to other members of the social group. Apart from somatic and communication characteristics determining chances of an individual to succeed in the social competition, the internal regulation of these aspects presents another interesting subject for studies. In this respect a special attention...
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Maternal Investment Strategy in Model Monotocous and Polytocous Mammals: A Life-History Perspective
Dušek, Adam
The litter size is one of the most important determinants of mammalian life-histories. Depending on the size of the litter, the mammals can be divided into two main groups: (1) the monotocous mammals, producing only one offspring per litter; and (2) the polytocous mammals, producing more than one offspring per litter. This life-history dichotomy entails different strategies whereby the mammalian females may optimize their maternal investment. The aim of this Ph.D. thesis is to show variation in the maternal investment strategies of monotocous and polytocous mammals from a life-history perspective. In order to address this issue, I investigated the strategy of maternal investment in the red deer (Cervus elaphus), representing a typical monotocous mammal, and the house mouse (Mus musculus), representing a typical polytocous mammal. From a life-history perspective, the red deer, producing no more than one litter per year, can be viewed as a model of "K-selected species", while the house mouse, producing up to ten litters per year, can be viewed as a model of "r- selected species". The red deer and the house mouse are ideal model organisms for this type of research also because they both are representatives of the most common mammalian mating system - the simultaneous polygyny. A general assumption of...
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Strategie mateřské investice u modelového monotokního a polytokního savce z pohledu životní historie
Dušek, Adam ; Stopka, Pavel (advisor) ; Šumbera, Radim (referee) ; Tkadlec, Emil (referee)
The litter size is one of the most important determinants of mammalian life-histories. Depending on the size of the litter, the mammals can be divided into two main groups: (1) the monotocous mammals, producing only one offspring per litter; and (2) the polytocous mammals, producing more than one offspring per litter. This life-history dichotomy entails different strategies whereby the mammalian females may optimize their maternal investment. The aim of this Ph.D. thesis is to show variation in the maternal investment strategies of monotocous and polytocous mammals from a life-history perspective. In order to address this issue, I investigated the strategy of maternal investment in the red deer (Cervus elaphus), representing a typical monotocous mammal, and the house mouse (Mus musculus), representing a typical polytocous mammal. From a life-history perspective, the red deer, producing no more than one litter per year, can be viewed as a model of "K-selected species", while the house mouse, producing up to ten litters per year, can be viewed as a model of "r- selected species". The red deer and the house mouse are ideal model organisms for this type of research also because they both are representatives of the most common mammalian mating system - the simultaneous polygyny. A general assumption of...
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