Latitudinal gradients display well-documented changes in annual daylight dynamics, environmental seasonality/stability and biotic interactions, providing a unique opportunity for testing hypotheses regarding the roles of extrinsic environmental factors and intrinsic physiological mechanisms in life-history evolution. Birds are particularly well suited for such analyses as their life-history variation has been well documented worldwide, with avian comparative studies having played a central role in elucidating patterns and mechanisms of variation in life-history traits. In general, clear latitudinal life-history gradients have been reported in birds with traits indicative of slow life-histories in low latitudes and fast life-histories in the north. In addition to the recent focus on changes in avian life-histories across latitudinal gradients, it is becoming apparent that studies along altitudinal gradients may provide additional (and complementary) insights on life history theory. Lower ambient temperatures (a decrease in mean temperature of 5.5 °C per km above sea level) and higher temporal variation in temperature amplitude at higher altitudes may increase mortality rates, or impose higher costs of thermoregulation and increased basal metabolic rates. The aim of this thesis is to provide an overview of current knowledge on latitudinal and altitudinal shifts in avian life-history traits, mainly focusing on reproductive and physiology traits, growth patterns, and survival.
Předběžná náplň práce v anglickém jazyce
Latitudinal gradients display well-documented changes in annual daylight dynamics, environmental seasonality/stability and biotic interactions, providing a unique opportunity for testing hypotheses regarding the roles of extrinsic environmental factors and intrinsic physiological mechanisms in life-history evolution. Birds are particularly well suited for such analyses as their life-history variation has been well documented worldwide, with avian comparative studies having played a central role in elucidating patterns and mechanisms of variation in life-history traits. In general, clear latitudinal life-history gradients have been reported in birds with traits indicative of slow life-histories in low latitudes and fast life-histories in the north. In addition to the recent focus on changes in avian life-histories across latitudinal gradients, it is becoming apparent that studies along altitudinal gradients may provide additional (and complementary) insights on life history theory. Lower ambient temperatures (a decrease in mean temperature of 5.5 °C per km above sea level) and higher temporal variation in temperature amplitude at higher altitudes may increase mortality rates, or impose higher costs of thermoregulation and increased basal metabolic rates. The aim of this thesis is to provide an overview of current knowledge on latitudinal and altitudinal shifts in avian life histories, mainly focusing on reproductive and physiology traits, growth patterns, and survival.
- zadáno a potvrzeno stud. odd.