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Jacqueline D. Litzgus - One of the best experts on this subject based on the ideXlab platform.
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Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta
Behavioral Ecology and Sociobiology, 2020Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle ( Chrysemys picta ) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Significance statement Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles ( Chrysemys picta ) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.
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Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta
Behavioral Ecology and Sociobiology, 2020Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle (Chrysemys picta) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles (Chrysemys picta) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.
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Sex-biased seasonal capture rates in Painted Turtle ( Chrysemys picta )
The Canadian Field-Naturalist, 2018Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:We examined captures of Painted Turtle ( Chrysemys picta ) in Algonquin Provincial Park, Ontario, Canada, during the understudied summer–autumn transition period (August–September). The proportion of captured male turtles increased relative to the proportion of females during the late summer and early autumn sampling period, leading to male-biased capture rates in a population with a strongly female-biased sex ratio. We consider explanations for the capture bias in relation to sex-specific activity patterns and briefly discuss the implications of sampling period on the outcome of population structure studies.
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Diet and Feeding Behaviour of Snapping Turtles ( Chelydra serpentina ) and Midland Painted Turtles ( Chrysemys picta marginata ) in Algonquin Provincial Park, Ontario
The Canadian Field-Naturalist, 2016Co-Authors: Patrick D. Moldowan, Matthew G. Keevil, Peter B. Mills, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:We compare diet and feeding behaviour of Snapping Turtles ( Chelydra serpentina ) and Midland Painted Turtles ( Chrysemys picta marginata ) in Algonquin Provincial Park, Ontario, Canada. We observed young Chelydra and Chrysemys turtles feeding on insect and amphibian larvae in ephemeral ponds, adult Chrysemys terrestrially foraging on odonate larvae, and adult Chelydra consuming aquatic vegetation and seeds. These and other observations highlight the importance of seasonally available habitat and food for juvenile turtles. We also discuss the evidence for, and importance of, turtles as seed-dispersal agents for aquatic vegetation. Illustrative video recordings accompany our dietary observations.
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growth sexual maturity and reproduction of a female midland painted turtle Chrysemys picta marginata afflicted with kyphosis
Chelonian Conservation and Biology, 2015Co-Authors: Patrick D. Moldowan, Matthew G. Keevil, Ronald J. Brooks, Nicola Koper, Jacqueline D. LitzgusAbstract:Abstract Kyphosis, a congenital humpback condition of the spinal column, has been reported across a broad range of chelonian taxa. These reports are often of single observations and lack background information about the history of the animal(s) involved. A kyphotic female midland painted turtle (Chrysemys picta marginata) reported herein is a member of a long-term mark–recapture study in Algonquin Park (Ontario, Canada), providing a unique opportunity to document life-history characters of a kyphotic turtle over 18 yrs and draw comparisons to other members of her cohort and population. Despite her spinal deformity, the somatic growth, body size, age at sexual maturity, and reproduction of the kyphotic female have been similar to those of nonkyphotic females in our long-term study population, suggesting that the condition has not compromised her fitness.
Patrick D. Moldowan - One of the best experts on this subject based on the ideXlab platform.
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Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta
Behavioral Ecology and Sociobiology, 2020Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle ( Chrysemys picta ) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Significance statement Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles ( Chrysemys picta ) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.
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Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta
Behavioral Ecology and Sociobiology, 2020Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle (Chrysemys picta) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles (Chrysemys picta) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.
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Sex-biased seasonal capture rates in Painted Turtle ( Chrysemys picta )
The Canadian Field-Naturalist, 2018Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:We examined captures of Painted Turtle ( Chrysemys picta ) in Algonquin Provincial Park, Ontario, Canada, during the understudied summer–autumn transition period (August–September). The proportion of captured male turtles increased relative to the proportion of females during the late summer and early autumn sampling period, leading to male-biased capture rates in a population with a strongly female-biased sex ratio. We consider explanations for the capture bias in relation to sex-specific activity patterns and briefly discuss the implications of sampling period on the outcome of population structure studies.
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Diet and Feeding Behaviour of Snapping Turtles ( Chelydra serpentina ) and Midland Painted Turtles ( Chrysemys picta marginata ) in Algonquin Provincial Park, Ontario
The Canadian Field-Naturalist, 2016Co-Authors: Patrick D. Moldowan, Matthew G. Keevil, Peter B. Mills, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:We compare diet and feeding behaviour of Snapping Turtles ( Chelydra serpentina ) and Midland Painted Turtles ( Chrysemys picta marginata ) in Algonquin Provincial Park, Ontario, Canada. We observed young Chelydra and Chrysemys turtles feeding on insect and amphibian larvae in ephemeral ponds, adult Chrysemys terrestrially foraging on odonate larvae, and adult Chelydra consuming aquatic vegetation and seeds. These and other observations highlight the importance of seasonally available habitat and food for juvenile turtles. We also discuss the evidence for, and importance of, turtles as seed-dispersal agents for aquatic vegetation. Illustrative video recordings accompany our dietary observations.
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growth sexual maturity and reproduction of a female midland painted turtle Chrysemys picta marginata afflicted with kyphosis
Chelonian Conservation and Biology, 2015Co-Authors: Patrick D. Moldowan, Matthew G. Keevil, Ronald J. Brooks, Nicola Koper, Jacqueline D. LitzgusAbstract:Abstract Kyphosis, a congenital humpback condition of the spinal column, has been reported across a broad range of chelonian taxa. These reports are often of single observations and lack background information about the history of the animal(s) involved. A kyphotic female midland painted turtle (Chrysemys picta marginata) reported herein is a member of a long-term mark–recapture study in Algonquin Park (Ontario, Canada), providing a unique opportunity to document life-history characters of a kyphotic turtle over 18 yrs and draw comparisons to other members of her cohort and population. Despite her spinal deformity, the somatic growth, body size, age at sexual maturity, and reproduction of the kyphotic female have been similar to those of nonkyphotic females in our long-term study population, suggesting that the condition has not compromised her fitness.
Ronald J. Brooks - One of the best experts on this subject based on the ideXlab platform.
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Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta
Behavioral Ecology and Sociobiology, 2020Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle ( Chrysemys picta ) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Significance statement Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles ( Chrysemys picta ) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.
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Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta
Behavioral Ecology and Sociobiology, 2020Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle (Chrysemys picta) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles (Chrysemys picta) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.
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Sex-biased seasonal capture rates in Painted Turtle ( Chrysemys picta )
The Canadian Field-Naturalist, 2018Co-Authors: Patrick D. Moldowan, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:We examined captures of Painted Turtle ( Chrysemys picta ) in Algonquin Provincial Park, Ontario, Canada, during the understudied summer–autumn transition period (August–September). The proportion of captured male turtles increased relative to the proportion of females during the late summer and early autumn sampling period, leading to male-biased capture rates in a population with a strongly female-biased sex ratio. We consider explanations for the capture bias in relation to sex-specific activity patterns and briefly discuss the implications of sampling period on the outcome of population structure studies.
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Diet and Feeding Behaviour of Snapping Turtles ( Chelydra serpentina ) and Midland Painted Turtles ( Chrysemys picta marginata ) in Algonquin Provincial Park, Ontario
The Canadian Field-Naturalist, 2016Co-Authors: Patrick D. Moldowan, Matthew G. Keevil, Peter B. Mills, Ronald J. Brooks, Jacqueline D. LitzgusAbstract:We compare diet and feeding behaviour of Snapping Turtles ( Chelydra serpentina ) and Midland Painted Turtles ( Chrysemys picta marginata ) in Algonquin Provincial Park, Ontario, Canada. We observed young Chelydra and Chrysemys turtles feeding on insect and amphibian larvae in ephemeral ponds, adult Chrysemys terrestrially foraging on odonate larvae, and adult Chelydra consuming aquatic vegetation and seeds. These and other observations highlight the importance of seasonally available habitat and food for juvenile turtles. We also discuss the evidence for, and importance of, turtles as seed-dispersal agents for aquatic vegetation. Illustrative video recordings accompany our dietary observations.
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growth sexual maturity and reproduction of a female midland painted turtle Chrysemys picta marginata afflicted with kyphosis
Chelonian Conservation and Biology, 2015Co-Authors: Patrick D. Moldowan, Matthew G. Keevil, Ronald J. Brooks, Nicola Koper, Jacqueline D. LitzgusAbstract:Abstract Kyphosis, a congenital humpback condition of the spinal column, has been reported across a broad range of chelonian taxa. These reports are often of single observations and lack background information about the history of the animal(s) involved. A kyphotic female midland painted turtle (Chrysemys picta marginata) reported herein is a member of a long-term mark–recapture study in Algonquin Park (Ontario, Canada), providing a unique opportunity to document life-history characters of a kyphotic turtle over 18 yrs and draw comparisons to other members of her cohort and population. Despite her spinal deformity, the somatic growth, body size, age at sexual maturity, and reproduction of the kyphotic female have been similar to those of nonkyphotic females in our long-term study population, suggesting that the condition has not compromised her fitness.
Gary C. Packard - One of the best experts on this subject based on the ideXlab platform.
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Accumulation of lactate by frozen painted turtles (Chrysemys picta) and its relationship to freeze tolerance.
Physiological and biochemical zoology : PBZ, 2004Co-Authors: Mary J. Packard, Gary C. PackardAbstract:Abstract Hatchling painted turtles (Chrysemys picta) survived freezing at −2°C for 4 d, few recovered from freezing lasting 6 d, and none survived being frozen for 8 d. Whole‐body glucose and lactate were low in animals that had not been subjected to cold and ice but increased precipitously in animals that were frozen for 2 d. Both metabolites continued to increase, but at a somewhat lower rate, in animals frozen for 4, 6, or 8 d. The increase in whole‐body lactate reflects a reliance by frozen hatchlings on anaerobiosis, whereas the increase in glucose presumably results from mobilization of glycogen reserves to support anaerobic metabolism. Mortality of frozen hatchlings is correlated with the increase in whole‐body lactate. Factors that may contribute to the observed correlation include a compromised capacity for individual organs to cope with the lactic acidosis that accompanies anaerobic metabolism and organ‐specific depletion of energy reserves. Individual organs must rely on buffering and glucose r...
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Cold-tolerance of hatchling painted turtles (Chrysemys picta bellii) from the Southern limit of distribution
Journal of Herpetology, 2002Co-Authors: Gary C. Packard, Mary J. Packard, Carrie L. Morjan, Fredric J. JanzenAbstract:Painted turtles (Chrysemys picta) have a natural history unlike that of other chelonians from the northern United States and southern Canada. Although neonates of other freshwater turtles usually emerge from their subterranean nests in late summer or autumn and move to nearby marshes, lakes, or streams to spend their first winter, hatchling painted turtles typically remain inside their shallow (8-14 cm) nests throughout their first winter and do not emerge above ground until the following spring (Ernst et al., 1994). This behavior commonly causes neonatal painted turtles from Nebraska (Packard, 1997; Packard et al., 1997a), northern Illinois (Weisrock and Janzen, 1999), and New Jersey (DePari, 1996) northward to the limit of distribution in southern Canada (Storey et al., 1988)
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Developmental plasticity in Painted Turtles, Chrysemys picta
Functional Ecology, 2000Co-Authors: Gary C. Packard, Mary J. PackardAbstract:1. The contents of newly constructed nests of Painted Turtles, Chrysemys picta, were manipulated by reciprocal transplant, so that each of several nests received a complement of eggs from each of several females. The eggs were recovered from nests after 8 weeks and allowed to complete incubation under standard conditions in the laboratory. 2. Live mass, dry mass and water content of carcasses, and dry mass of unused yolk, varied significantly among hatchlings from eggs that incubated in different nests. Indeed, hatchlings from different nests sometimes differed as much in size or physiological condition as animals from different clutches. 3. Stepwise linear regression indicated that size of hatchlings and water content of their carcasses were positively correlated with water exchanges by eggs whereas mass of the unused yolk was negatively correlated with water exchanges. Although the statistical procedure is only correlative, the findings accord well with results of laboratory studies documenting a relationship between uptake of water by eggs, metabolism and growth by embryos, and size and condition of hatchlings. 4. Developmental plasticity, coupled with variation in the physical environment within and among nests, probably accounts (minimally) for 19% of the variation in live mass of hatchlings in the field; 24% of the variation in dry mass of carcasses; 11% of the variation in hydration of carcasses; and 26% of the variation in dry mass of unused yolk. Such variation may impact survival by neonatal animals, and needs to be addressed explicitly by models for the evolution of life history in Painted Turtles.
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Resistance to freezing in hatchling painted turtles (Chrysemys picta)
Canadian Journal of Zoology, 1999Co-Authors: Gary C. Packard, Jeffrey W Lang, Leslie D. Lohmiller, Mary J. PackardAbstract:We assessed the ability of hatchling painted turtles (Chrysemys picta) from northern Minnesota to resist freezing when exposed to conditions like those occurring in natural hibernacula (natal nests). We placed animals individually into artificial hibernacula constructed in jars of damp, loamy sand and then lowered the temperature to approximately -0.4°C, which was below the equilibrium freezing point for water in the soil (approximately -0.1°C) but above that for body fluids of the turtles (approximately -0.7°C). Next, ice was used to initiate freezing of water in the soil, after which the substratum was allowed to freeze to an equilibrium temperature of -0.4°C. The minimum temperature then was reduced by 1°C/day to either -2.5 or -6.5°C. The minimum was maintained for 9 days in the former treatment and for 5 days in the latter, so that turtles in both treatments were exposed for the same length of time to temperatures below the equilibrium freezing point for their body fluids. Some animals in each treatm...
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Thermal environment for overwintering hatchlings of the painted turtle (Chrysemys picta)
Canadian Journal of Zoology, 1997Co-Authors: Gary C. Packard, Leslie D. Lohmiller, Sarah L. Fasano, Marcus B. Attaway, Trina L. LynchAbstract:We monitored temperatures during the winter of 1995–1996 inside 18 nests containing hatchling painted turtles (Chrysemys picta). The study was performed at the Valentine National Wildlife Refuge in north-central Nebraska to assess survival of neonatal turtles in relation to the thermal environment inside their hibernacula. Minimum temperatures in the nests varied from −3 to −21 °C, and were better predictors of survival of hatchlings than other measures of the thermal environment. All hatchlings survived in nests where the temperature never went below −7 °C, some animals survived in nests where the minimum was between −7 and −13 °C, but no turtle survived in a nest where the minimum was below −14 °C. Hatchlings probably survived the cold by sustaining a state of supercooling, because the duration of exposure to low temperatures was far too long for animals in most nests to have survived in a frozen state.
Mary J. Packard - One of the best experts on this subject based on the ideXlab platform.
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Accumulation of lactate by frozen painted turtles (Chrysemys picta) and its relationship to freeze tolerance.
Physiological and biochemical zoology : PBZ, 2004Co-Authors: Mary J. Packard, Gary C. PackardAbstract:Abstract Hatchling painted turtles (Chrysemys picta) survived freezing at −2°C for 4 d, few recovered from freezing lasting 6 d, and none survived being frozen for 8 d. Whole‐body glucose and lactate were low in animals that had not been subjected to cold and ice but increased precipitously in animals that were frozen for 2 d. Both metabolites continued to increase, but at a somewhat lower rate, in animals frozen for 4, 6, or 8 d. The increase in whole‐body lactate reflects a reliance by frozen hatchlings on anaerobiosis, whereas the increase in glucose presumably results from mobilization of glycogen reserves to support anaerobic metabolism. Mortality of frozen hatchlings is correlated with the increase in whole‐body lactate. Factors that may contribute to the observed correlation include a compromised capacity for individual organs to cope with the lactic acidosis that accompanies anaerobic metabolism and organ‐specific depletion of energy reserves. Individual organs must rely on buffering and glucose r...
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Cold-tolerance of hatchling painted turtles (Chrysemys picta bellii) from the Southern limit of distribution
Journal of Herpetology, 2002Co-Authors: Gary C. Packard, Mary J. Packard, Carrie L. Morjan, Fredric J. JanzenAbstract:Painted turtles (Chrysemys picta) have a natural history unlike that of other chelonians from the northern United States and southern Canada. Although neonates of other freshwater turtles usually emerge from their subterranean nests in late summer or autumn and move to nearby marshes, lakes, or streams to spend their first winter, hatchling painted turtles typically remain inside their shallow (8-14 cm) nests throughout their first winter and do not emerge above ground until the following spring (Ernst et al., 1994). This behavior commonly causes neonatal painted turtles from Nebraska (Packard, 1997; Packard et al., 1997a), northern Illinois (Weisrock and Janzen, 1999), and New Jersey (DePari, 1996) northward to the limit of distribution in southern Canada (Storey et al., 1988)
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Developmental plasticity in Painted Turtles, Chrysemys picta
Functional Ecology, 2000Co-Authors: Gary C. Packard, Mary J. PackardAbstract:1. The contents of newly constructed nests of Painted Turtles, Chrysemys picta, were manipulated by reciprocal transplant, so that each of several nests received a complement of eggs from each of several females. The eggs were recovered from nests after 8 weeks and allowed to complete incubation under standard conditions in the laboratory. 2. Live mass, dry mass and water content of carcasses, and dry mass of unused yolk, varied significantly among hatchlings from eggs that incubated in different nests. Indeed, hatchlings from different nests sometimes differed as much in size or physiological condition as animals from different clutches. 3. Stepwise linear regression indicated that size of hatchlings and water content of their carcasses were positively correlated with water exchanges by eggs whereas mass of the unused yolk was negatively correlated with water exchanges. Although the statistical procedure is only correlative, the findings accord well with results of laboratory studies documenting a relationship between uptake of water by eggs, metabolism and growth by embryos, and size and condition of hatchlings. 4. Developmental plasticity, coupled with variation in the physical environment within and among nests, probably accounts (minimally) for 19% of the variation in live mass of hatchlings in the field; 24% of the variation in dry mass of carcasses; 11% of the variation in hydration of carcasses; and 26% of the variation in dry mass of unused yolk. Such variation may impact survival by neonatal animals, and needs to be addressed explicitly by models for the evolution of life history in Painted Turtles.
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Resistance to freezing in hatchling painted turtles (Chrysemys picta)
Canadian Journal of Zoology, 1999Co-Authors: Gary C. Packard, Jeffrey W Lang, Leslie D. Lohmiller, Mary J. PackardAbstract:We assessed the ability of hatchling painted turtles (Chrysemys picta) from northern Minnesota to resist freezing when exposed to conditions like those occurring in natural hibernacula (natal nests). We placed animals individually into artificial hibernacula constructed in jars of damp, loamy sand and then lowered the temperature to approximately -0.4°C, which was below the equilibrium freezing point for water in the soil (approximately -0.1°C) but above that for body fluids of the turtles (approximately -0.7°C). Next, ice was used to initiate freezing of water in the soil, after which the substratum was allowed to freeze to an equilibrium temperature of -0.4°C. The minimum temperature then was reduced by 1°C/day to either -2.5 or -6.5°C. The minimum was maintained for 9 days in the former treatment and for 5 days in the latter, so that turtles in both treatments were exposed for the same length of time to temperatures below the equilibrium freezing point for their body fluids. Some animals in each treatm...
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Cold Tolerance in Hatchling Painted Turtles (Chrysemys picta): Supercooling or Tolerance for Freezing?
Physiological zoology, 1997Co-Authors: Gary C. Packard, Jeffrey W Lang, Leslie D. Lohmiller, Mary J. PackardAbstract:ABSTRACT We studied tolerance for cold in hatchling painted turtles (Chrysemys picta) from Lake Metigoshe, Bottineau County, North Dakota, to determine whether neonates in populations near the northern limit of distribution rely on a tolerance for freezing or on a capacity for supercooling to survive their first winter of life. We placed hatchlings individually into artificial hibernacula constructed in jars of damp, loamy sand and then cooled the jars to approximately −0.45°C, which was below the equilibrium freezing point for water held by the sand but above that for body fluids of the neonatal turtles. A piece of ice next was placed on the surface of the sand in each jar to induce freezing of the soil water. After the soil water had frozen to an equilibrium, the temperature in the jars was lowered by 1°C/d to minima averaging −2.5°C, −4.5°C, −6.5°C, and −10.5°C in different treatments. These temperatures were maintained for varying periods, so that animals in each treatment were exposed to temperatures...