- Email: [email protected]
4.P1. Genetic correlation between metabolic rate and food consumption in the bank vole: Consequence for evolution of endothermy
Abstracts / Comparative Biochemistry and Physiology, Part A 148 (2007) S17–S23
levels. Among species, variation in nightly or seasonal patterns of calling activity, such as species that breed for prolonged or continuous periods and those that breed more opportunistically, provides opportunities to study different reproductive strategies and the relationship of calling behavior to overall patterns of energy use. Individual males of a species exhibit variation in call characteristics that influence male competition and female choice. This variation is largely driven by physiological capacity to produce energetically expensive calls. Female preferences are often based on dynamic properties of the male's call, and females of many species have been shown to prefer acoustic traits that are more energetically expensive. Ultimately such individual variation should influence male reproductive success but only a few investigations have demonstrated beneficial effects, such as greater hatching success or tadpole survival, in offspring of males that produce calls with characteristics preferred by females. I will present an overview of the physiological and biochemical correlates of calling behavior, and discuss how variation in these traits affects male fitness in anuran amphibians. doi:10.1016/j.cbpa.2007.06.044
S19
correlations with life histories of whole animal energy metabolism. Our results suggest that physiological traits of animals are traits with a complex genetic architecture, with additive genetic components in some cases, maternal– nonadditive variance in others, interacting with morphological and life history traits through genetic covariances. These results suggest a high evolutionary potential to the physiological phenotype, and the resulting optima will depend on the form of the adaptive landscape in the population at a given time. doi:10.1016/j.cbpa.2007.06.045
4.P1. Genetic correlation between metabolic rate and food consumption in the bank vole: Consequence for evolution of endothermy Sadowska, E.T., Stanisz, A., Baliga-Klimczyk, K., Labocha, M.K., and Koteja, P. Jagiellonian University, Poland [email protected]
4.6. Heritability of physiological traits: The case of metabolic rate Nespolo, R.F. Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile. Casilla 567, Valdivia, Chile [email protected] Evolutionary physiology is an emerging discipline with roots in comparative physiology. One major change in the emergence of this discipline was an explicit new focus on viewing organisms as the evolutionary products of natural selection. The shift in research emphasis from comparative physiology to evolutionary physiology has resulted in physiological traits becoming important elements in broad research programs of evolution and ecology. Evolutionary quantitative genetics is a theory-based biological discipline that has developed the quantitative tools to test explicit evolutionary hypotheses. The role of quantitative genetics has been paramount, in studying the microevolution of morphology, behavior and life history, but not physiology. As a consequence, little basic information is known such as additive genetic variation of physiological traits and the magnitude of genetically based trade-offs (i.e., genetic correlations) with other traits. With these motivations in mind, we have developed a research program aimed to decompose the sources of phenotypic variation in animals. Some of our research goals have been to assess (1) the inter-individual variation, (2) amount of additive genetic variance and (3) the genetic
The main focus of our experiment is on the question concerning the sources of interspecific variation in basal metabolic rate (BMR) and mechanisms behind evolution of endothermy in mammals. We have already reported that in the bank vole, Myodes (=Clethrionomys) glareolus, mass-independent BMR is positively genetically correlated with the aerobic capacity achieved in an exercise test (ACswim) but not during cold exposure (ACcold). Here, we test the hypothesis that total energy budget, measured as food consumption, is positively genetically correlated with BMR and ACswim but not with ACcold. The experiment was performed on about 750 males (mean ± S.D.; body mass = 21.2 ± 2.9 g; age = 103 ± 30 days) from six generations bred in laboratory. BMR was measured at thermally neutral temperature in fasted animals. The aerobic capacity was measured in two ways, to distinguish between locomotor performance (swimming) and thermogenic capacity (cold exposure). Food consumption was measured in a 4-day trial. Values of food consumption (4.3 ± 0.7 g/day), BMR (52.5 ± 6.0 ml O2/h), ACswim (257.2 ± 30.5 ml O2/h) and ACcold (270.5 ± 37.3 ml O2/h) varied remarkably among individuals. Food consumption increased with body mass of individuals (r = 0.53, p b 0.001) and with body mass gain during the trail (r = 0.31, p b 0.001). Narrow-sense heritability of mass-independent food consumption (corrected also for body mass changes) was 0.19 (p b 0.001). There is a positive additive genetic correlation between the food consumption and BMR (rA = 0.46) and ACswim (rA = 0.49), and there is no evidence for the genetic correlation between food consumption and ACcold. The results are consistent with a hypothesis that high BMR and endothermy in mammals evolved in connection with evolution of locomotor capabilities and high overall daily
S20
Abstracts / Comparative Biochemistry and Physiology, Part A 148 (2007) S17–S23
energy expenditures, rather than as a result of selection for thermoregulatory capacity. doi:10.1016/j.cbpa.2007.06.046
4.P2. Basal metabolic rate and life history in the bank vole, Myodes glareolus Sadowska, E.T., Baliga-Klimczyk, K., Labocha, M.K., and Koteja, P. Jagiellonian University, Poland [email protected] We test the hypothesis that high basal metabolic rate (BMR) evolved as a correlated response to selection for high reproductive effort. The experiment was performed on a laboratory colony of the bank vole, Myodes (=Clethrionomys) glareolus. BMR was measured in standard way in about 900 males (53.2 ± 6.1 ml O2/h) and 100 females (50.2 ± 5.7 ml O2/h). About 65% of 2000 pairs reproduced (females body mass = 19.4 ± 3.2 g; males = 23.2 ± 3.4 g; mean ± S.D.). Reproductive success (“reproduced or not”) of males did not depend on body mass, but heavier females gave birth more often (r = 0.08, p = 0.001). As a measure of reproductive effort of females we used litter size at birth (4.2 ± 1.3), litter mass at birth (7.9 ± 2.4 g), litter size at weaning (3.9 ± 1.3) and litter mass at weaning (38.8 ± 13.2 g). At the phenotypic level, there was no correlation between mass-independent BMR and reproductive success or reproductive effort (p N 0.48). Mass-independent values (corrected for female mass) of litter size and litter mass at birth were not heritable (h2 b 0.03, p N 0.54), heritability of litter size and litter mass at weaning was low (size: h2 = 0.06, p = 0.032; mass: h2 = 0.09, p b 0.001), whereas that of BMR was high (h2 = 0.40, p b 0.001). There was no significant additive genetic correlation between BMR and any of these life history traits. Thus, although both BMR and litter size and mass at weaning could respond to selection, the results do not provide an evidence that high levels of BMR could evolve in response to selection for high reproductive output. doi:10.1016/j.cbpa.2007.06.047
4.P3. Repeatability and heritability of basal metabolic rate in the zebra finch Rønning, B., Bech, C., Moe, B., and Jensen, H. Norwegian University of Science and Technology, Norway [email protected] Basal metabolic rate (BMR) is a physiological trait believed to show adaptational changes related to different habitats and way of life. A stable intra-individual variation (repeatability) is one
prerequisite for a trait to evolve through natural selection. We tested whether BMR was a repeatable over a considerable time of the life span of a small passerine finch: the zebra finch (Taeniopygia guttata). Residual values, controlled for the effect of body mass, showed significant repeatabilities over a short (1.5 months) and over a long period (2.5 years). Thus, these results show that there is consistent individual variation in BMR on which natural selection can work upon provided that this trait is heritable. For a trait to respond to selection some heritable genetic variation has to be present. In our study population of captive zebra finches (n = 349), we found evidence for a significant heritable genetic component in mass-dependent BMR (h2 = 0.25). Mass-dependent BMR is, however, strongly correlated to body mass. Selection rarely operates on only one trait at the time, and when there is a genetic correlation between traits, selection on one trait will influence traits with which it is correlated. Not surprisingly BMR was significantly genetically correlated to body mass and several size related traits in the zebra finch. When conditioned on the genetic variance in body mass, the heritability of BMR was substantially reduced (h2 = 0.04). Hence, our results indicate that genetic changes in BMR through directional selection are possible, but the potential for adaptation independent of body mass may be limited. doi:10.1016/j.cbpa.2007.06.048
4.P4. Selection for high basal metabolic rate compromises immune response in cold-stressed laboratory mice Ksiazek, A., Konarzewski, M., Chadzińska, M., and Cichoń, M. University of Bialystok, Institute of Biology, Poland [email protected] The significance of energetic costs of mounting an immune response is still debatable. To test whether these costs affect energy budgets, mice from two lines divergently selected for high (H-BMR) and low (L-BMR) basal rate of metabolism (BMR) were immunised with sheep red blood cells (SRBC) on day 10 of 16-day-long exposure to ambient temperature of either 23 or 5 °C. Mice of both lines responded to cold with a considerable increase in food intake, a reduction of food digestibility and an increase of mass of small intestine, heart and kidneys (but not liver). Cold exposure reduced immune response to SRBC in both lines. However, this reduction was significantly larger and accompanied by lower thymus and small intestine mass in H-BMR mice than in L-BMR mice, as indicated by significant line x temperature interactions. Furthermore, H-BMR mice responded to cold with reduced levels of production of interleukin-4. We thus demonstrated that in animals characterized by high energy expenditures the costs of mounting of an immune response have (1) lower physiological priority than thermoregulation and (2) are significantly
levels. Among species, variation in nightly or seasonal patterns of calling activity, such as species that breed for prolonged or continuous periods and those that breed more opportunistically, provides opportunities to study different reproductive strategies and the relationship of calling behavior to overall patterns of energy use. Individual males of a species exhibit variation in call characteristics that influence male competition and female choice. This variation is largely driven by physiological capacity to produce energetically expensive calls. Female preferences are often based on dynamic properties of the male's call, and females of many species have been shown to prefer acoustic traits that are more energetically expensive. Ultimately such individual variation should influence male reproductive success but only a few investigations have demonstrated beneficial effects, such as greater hatching success or tadpole survival, in offspring of males that produce calls with characteristics preferred by females. I will present an overview of the physiological and biochemical correlates of calling behavior, and discuss how variation in these traits affects male fitness in anuran amphibians. doi:10.1016/j.cbpa.2007.06.044
S19
correlations with life histories of whole animal energy metabolism. Our results suggest that physiological traits of animals are traits with a complex genetic architecture, with additive genetic components in some cases, maternal– nonadditive variance in others, interacting with morphological and life history traits through genetic covariances. These results suggest a high evolutionary potential to the physiological phenotype, and the resulting optima will depend on the form of the adaptive landscape in the population at a given time. doi:10.1016/j.cbpa.2007.06.045
4.P1. Genetic correlation between metabolic rate and food consumption in the bank vole: Consequence for evolution of endothermy Sadowska, E.T., Stanisz, A., Baliga-Klimczyk, K., Labocha, M.K., and Koteja, P. Jagiellonian University, Poland [email protected]
4.6. Heritability of physiological traits: The case of metabolic rate Nespolo, R.F. Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile. Casilla 567, Valdivia, Chile [email protected] Evolutionary physiology is an emerging discipline with roots in comparative physiology. One major change in the emergence of this discipline was an explicit new focus on viewing organisms as the evolutionary products of natural selection. The shift in research emphasis from comparative physiology to evolutionary physiology has resulted in physiological traits becoming important elements in broad research programs of evolution and ecology. Evolutionary quantitative genetics is a theory-based biological discipline that has developed the quantitative tools to test explicit evolutionary hypotheses. The role of quantitative genetics has been paramount, in studying the microevolution of morphology, behavior and life history, but not physiology. As a consequence, little basic information is known such as additive genetic variation of physiological traits and the magnitude of genetically based trade-offs (i.e., genetic correlations) with other traits. With these motivations in mind, we have developed a research program aimed to decompose the sources of phenotypic variation in animals. Some of our research goals have been to assess (1) the inter-individual variation, (2) amount of additive genetic variance and (3) the genetic
The main focus of our experiment is on the question concerning the sources of interspecific variation in basal metabolic rate (BMR) and mechanisms behind evolution of endothermy in mammals. We have already reported that in the bank vole, Myodes (=Clethrionomys) glareolus, mass-independent BMR is positively genetically correlated with the aerobic capacity achieved in an exercise test (ACswim) but not during cold exposure (ACcold). Here, we test the hypothesis that total energy budget, measured as food consumption, is positively genetically correlated with BMR and ACswim but not with ACcold. The experiment was performed on about 750 males (mean ± S.D.; body mass = 21.2 ± 2.9 g; age = 103 ± 30 days) from six generations bred in laboratory. BMR was measured at thermally neutral temperature in fasted animals. The aerobic capacity was measured in two ways, to distinguish between locomotor performance (swimming) and thermogenic capacity (cold exposure). Food consumption was measured in a 4-day trial. Values of food consumption (4.3 ± 0.7 g/day), BMR (52.5 ± 6.0 ml O2/h), ACswim (257.2 ± 30.5 ml O2/h) and ACcold (270.5 ± 37.3 ml O2/h) varied remarkably among individuals. Food consumption increased with body mass of individuals (r = 0.53, p b 0.001) and with body mass gain during the trail (r = 0.31, p b 0.001). Narrow-sense heritability of mass-independent food consumption (corrected also for body mass changes) was 0.19 (p b 0.001). There is a positive additive genetic correlation between the food consumption and BMR (rA = 0.46) and ACswim (rA = 0.49), and there is no evidence for the genetic correlation between food consumption and ACcold. The results are consistent with a hypothesis that high BMR and endothermy in mammals evolved in connection with evolution of locomotor capabilities and high overall daily
S20
Abstracts / Comparative Biochemistry and Physiology, Part A 148 (2007) S17–S23
energy expenditures, rather than as a result of selection for thermoregulatory capacity. doi:10.1016/j.cbpa.2007.06.046
4.P2. Basal metabolic rate and life history in the bank vole, Myodes glareolus Sadowska, E.T., Baliga-Klimczyk, K., Labocha, M.K., and Koteja, P. Jagiellonian University, Poland [email protected] We test the hypothesis that high basal metabolic rate (BMR) evolved as a correlated response to selection for high reproductive effort. The experiment was performed on a laboratory colony of the bank vole, Myodes (=Clethrionomys) glareolus. BMR was measured in standard way in about 900 males (53.2 ± 6.1 ml O2/h) and 100 females (50.2 ± 5.7 ml O2/h). About 65% of 2000 pairs reproduced (females body mass = 19.4 ± 3.2 g; males = 23.2 ± 3.4 g; mean ± S.D.). Reproductive success (“reproduced or not”) of males did not depend on body mass, but heavier females gave birth more often (r = 0.08, p = 0.001). As a measure of reproductive effort of females we used litter size at birth (4.2 ± 1.3), litter mass at birth (7.9 ± 2.4 g), litter size at weaning (3.9 ± 1.3) and litter mass at weaning (38.8 ± 13.2 g). At the phenotypic level, there was no correlation between mass-independent BMR and reproductive success or reproductive effort (p N 0.48). Mass-independent values (corrected for female mass) of litter size and litter mass at birth were not heritable (h2 b 0.03, p N 0.54), heritability of litter size and litter mass at weaning was low (size: h2 = 0.06, p = 0.032; mass: h2 = 0.09, p b 0.001), whereas that of BMR was high (h2 = 0.40, p b 0.001). There was no significant additive genetic correlation between BMR and any of these life history traits. Thus, although both BMR and litter size and mass at weaning could respond to selection, the results do not provide an evidence that high levels of BMR could evolve in response to selection for high reproductive output. doi:10.1016/j.cbpa.2007.06.047
4.P3. Repeatability and heritability of basal metabolic rate in the zebra finch Rønning, B., Bech, C., Moe, B., and Jensen, H. Norwegian University of Science and Technology, Norway [email protected] Basal metabolic rate (BMR) is a physiological trait believed to show adaptational changes related to different habitats and way of life. A stable intra-individual variation (repeatability) is one
prerequisite for a trait to evolve through natural selection. We tested whether BMR was a repeatable over a considerable time of the life span of a small passerine finch: the zebra finch (Taeniopygia guttata). Residual values, controlled for the effect of body mass, showed significant repeatabilities over a short (1.5 months) and over a long period (2.5 years). Thus, these results show that there is consistent individual variation in BMR on which natural selection can work upon provided that this trait is heritable. For a trait to respond to selection some heritable genetic variation has to be present. In our study population of captive zebra finches (n = 349), we found evidence for a significant heritable genetic component in mass-dependent BMR (h2 = 0.25). Mass-dependent BMR is, however, strongly correlated to body mass. Selection rarely operates on only one trait at the time, and when there is a genetic correlation between traits, selection on one trait will influence traits with which it is correlated. Not surprisingly BMR was significantly genetically correlated to body mass and several size related traits in the zebra finch. When conditioned on the genetic variance in body mass, the heritability of BMR was substantially reduced (h2 = 0.04). Hence, our results indicate that genetic changes in BMR through directional selection are possible, but the potential for adaptation independent of body mass may be limited. doi:10.1016/j.cbpa.2007.06.048
4.P4. Selection for high basal metabolic rate compromises immune response in cold-stressed laboratory mice Ksiazek, A., Konarzewski, M., Chadzińska, M., and Cichoń, M. University of Bialystok, Institute of Biology, Poland [email protected] The significance of energetic costs of mounting an immune response is still debatable. To test whether these costs affect energy budgets, mice from two lines divergently selected for high (H-BMR) and low (L-BMR) basal rate of metabolism (BMR) were immunised with sheep red blood cells (SRBC) on day 10 of 16-day-long exposure to ambient temperature of either 23 or 5 °C. Mice of both lines responded to cold with a considerable increase in food intake, a reduction of food digestibility and an increase of mass of small intestine, heart and kidneys (but not liver). Cold exposure reduced immune response to SRBC in both lines. However, this reduction was significantly larger and accompanied by lower thymus and small intestine mass in H-BMR mice than in L-BMR mice, as indicated by significant line x temperature interactions. Furthermore, H-BMR mice responded to cold with reduced levels of production of interleukin-4. We thus demonstrated that in animals characterized by high energy expenditures the costs of mounting of an immune response have (1) lower physiological priority than thermoregulation and (2) are significantly