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David Crews - One of the best experts on this subject based on the ideXlab platform.
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Differences induced by incubation temperature, versus androgen manipulation, in male leopard geckos (Eublepharis macularius).
Physiology & Behavior, 2012Co-Authors: V. Huang, David CrewsAbstract:A fundamental tenet of sexual selection is that in sexually dimorphic traits, there is variation within a sex. In leopard geckos (Eublepharis macularius), a species with temperature-dependent sex determination, embryonic temperature contributes both to sex determination and polymorphisms within each sex. In this study we report that males from different incubation temperatures, one hitherto untested, exhibit significant differences in behavior even when castrated. Further, treatment with dihydrotestosterone increases scent marking, a territorial behavior. This supports previous results indicating that temperature has a direct organizing action on brain and sociosexual behavior independent of gonadal hormones.
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Constraints on temperature-dependent sex determination in the leopard gecko (Eublepharis macularius): response to Kratochvil et al.
Naturwissenschaften, 2008Co-Authors: Victoria Huang, Turk Rhen, Jon T. Sakata, Patricia Coomber, Sarah Simmonds, David CrewsAbstract:Kratochvil et al. (Naturwissenschaften 95:209–215, 2008 ) reported recently that in the leopard gecko ( Eublepharis macularius ) of the family Eublepharidae with temperature-dependent sex determination (TSD), clutches in which eggs were incubated at the same temperature produce only same-sex siblings. Interpreting this result in light of studies of sex steroid hormone involvement in sex determination, they suggested that maternally derived yolk steroid hormones could constrain sex-determining mechanisms in TSD reptiles. We have worked extensively with this species and have routinely incubated clutches at constant temperatures. To test the consistency of high frequency same-sex clutches across different incubation temperatures, we examined our records of clutches at the University of Texas at Austin from 1992 to 2001. We observed that clutches in which eggs were incubated at the same incubation temperature produced mixed-sex clutches as well as same-sex clutches. Furthermore, cases in which eggs within a clutch were separated and incubated at different temperatures produced the expected number of mixed-sex clutches. These results suggest that maternal influences on sex determination are secondary relative to incubation temperature effects.
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Reproductive tradeoffs and yolk steroids in female leopard geckos, Eublepharis macularius
Journal of Evolutionary Biology, 2006Co-Authors: Turk Rhen, David Crews, Albert J. Fivizzani, P. ElfAbstract:Life history theory predicts tradeoffs among reproductive traits, but the physiological mechanisms underlying such tradeoffs remain unclear. Here we examine reproductive tradeoffs and their association with yolk steroids in an oviparous lizard. Female leopard geckos lay two eggs in a clutch, produce multiple clutches in a breeding season, and reproduce for several years. We detected a significant tradeoff between egg size and the number of clutches laid by females during their first two breeding seasons. Total reproductive effort was strongly condition-dependent in the first season, but much less so in the second season. Although these and other tradeoffs were unmistakable, they were not associated with levels of androstenedione, oestradiol, or testosterone in egg yolk. Female condition and egg size, however, were inversely related to dihydrotestosterone (DHT) levels in egg yolk. Finally, steroid levels in egg yolk were not directly related to steroid levels in the maternal circulation when follicles were developing, indicating that steroid transfer to eggs is regulated. These findings suggest that maternal allocation of DHT could mitigate tradeoffs that lead to poor offspring quality (i.e. poor female condition) and small offspring size (i.e. small egg size).
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Social experience affects territorial and reproductive behaviours in male leopard geckos, Eublepharis macularius
Animal Behaviour, 2002Co-Authors: Jon T. Sakata, Ajay Gupta, Chien-pei Chuang, David CrewsAbstract:Abstract Social interactions have lasting effects on behaviour and physiology in a variety of organisms. In the leopard gecko, Eublepharis macularius , social experience alters neural metabolism and elevates circulating concentrations of androgens. In this study, we assessed the effects of social experience (housing with females versus housing in isolation) on the expression of social behaviours in male geckos (1) when gonadally intact, (2) following castration and (3) following testosterone administration. Given the neural and endocrine changes following social experience, we hypothesized that social experience would increase the capacity to display territorial and courtship behaviour in male leopard geckos. We found that intact males previously housed with females (experienced males) displayed more territorial marking and more activity when exposed to a neutral test arena relative to males housed in isolation (naive males). Experienced males continued to show more marking and activity in the testing arena relative to naive males following castration. However, the courtship behaviour of castrated naive and experienced males did not differ significantly. Following testosterone administration, experienced males again showed more activity in the empty test arena and tended to show more courtship behaviour. In summary, we found support for the hypothesis that social experience leads to changes in territorial and courtship behaviours and, moreover, found that male leopard geckos share some degree of commonality with other vertebrates in behavioural plasticity following social experience.
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organization and activation of sexual and agonistic behavior in the leopard gecko Eublepharis macularius
Neuroendocrinology, 2000Co-Authors: Turk Rhen, David CrewsAbstract:Gonadal sex is determined by the temperature experienced during incubation in the leopard gecko (Eublepharis macularius). Furthermore, both factors, incubation temperature and gonad
Gregorovičová Martina - One of the best experts on this subject based on the ideXlab platform.
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Význam jednotlivých složek repelentní sekrece Graphosoma lineatum vůči různým druhům predátorů
Univerzita Karlova Přírodovědecká fakulta, 2016Co-Authors: Gregorovičová MartinaAbstract:The chemical defence of Heteroptera is based on the repellent secretion that is very complex and consists of dozens chemical compounds. Heteroptera have good ability to produce/store large amounts of chemical components. The repellent secretion of Graphosoma lineatum is composed of many chemicals, such as short-chained aldehydes, which may signal the unpalatability of the bug to its potential predators or be directly toxic for them. The thesis is aimed at the major components of defensive secretion of Graphosoma lineatum - aldehydes - as well as the whole metathoracic scent-glands secretion of Graphosoma lineatum. The aversive reactions of four selected predators were evaluated: (1) leopard gecko (Eublepharis macularius); (2) green lizard (Lacerta viridis); (3) great tit (Parus major) and (4) blue tit (Cyanistes caeruleus). The following major compounds of the repellent secretion were tested: (1) the mixture of three aldehydes: (E)-hex-2-enal, (E)-oct-2-enal, (E)-dec-2-enal; (2) the mixture of three aldehydes and tridecane; (3) oxoaldehyde: (E)-4-oxohex-2-enal; (4) extracted metathoracic scent-glands secretion of Graphosoma lineatum adults; (5) hexane as a non-polar solvent and (6) pyrazine: 2-isobutyl-3-methoxypyrazine in experiments with leopard geckos as a positive control for excluding the...The chemical defence of Heteroptera is based on the repellent secretion that is very complex and consists of dozens chemical compounds. Heteroptera have good ability to produce/store large amounts of chemical components. The repellent secretion of Graphosoma lineatum is composed of many chemicals, such as short-chained aldehydes, which may signal the unpalatability of the bug to its potential predators or be directly toxic for them. The thesis is aimed at the major components of defensive secretion of Graphosoma lineatum - aldehydes - as well as the whole metathoracic scent-glands secretion of Graphosoma lineatum. The aversive reactions of four selected predators were evaluated: (1) leopard gecko (Eublepharis macularius); (2) green lizard (Lacerta viridis); (3) great tit (Parus major) and (4) blue tit (Cyanistes caeruleus). The following major compounds of the repellent secretion were tested: (1) the mixture of three aldehydes: (E)-hex-2-enal, (E)-oct-2-enal, (E)-dec-2-enal; (2) the mixture of three aldehydes and tridecane; (3) oxoaldehyde: (E)-4-oxohex-2-enal; (4) extracted metathoracic scent-glands secretion of Graphosoma lineatum adults; (5) hexane as a non-polar solvent and (6) pyrazine: 2-isobutyl-3-methoxypyrazine in experiments with leopard geckos as a positive control for excluding the...Department of ZoologyKatedra zoologiePřírodovědecká fakultaFaculty of Scienc
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Význam jednotlivých složek repelentní sekrece Graphosoma lineatum vůči různým druhům predátorů.
Univerzita Karlova Přírodovědecká fakulta, 2015Co-Authors: Gregorovičová MartinaAbstract:The chemical defence of Heteroptera is based on the repellent secretion that is very complex and consists of dozens chemical compounds. Heteroptera have good ability to produce/store large amounts of chemical components. The repellent secretion of Graphosoma lineatum is composed of many chemicals, such as short-chained aldehydes, which may signal the unpalatability of the bug to its potential predators or be directly toxic for them. The thesis is aimed at the major components of defensive secretion of Graphosoma lineatum - aldehydes - as well as the whole metathoracic scent-glands secretion of Graphosoma lineatum. The aversive reactions of four selected predators were evaluated: (1) leopard gecko (Eublepharis macularius); (2) green lizard (Lacerta viridis); (3) great tit (Parus major) and (4) blue tit (Cyanistes caeruleus). The following major compounds of the repellent secretion were tested: (1) the mixture of three aldehydes: (E)-hex-2-enal, (E)-oct-2-enal, (E)-dec-2-enal; (2) the mixture of three aldehydes and tridecane; (3) oxoaldehyde: (E)-4-oxohex-2-enal; (4) extracted metathoracic scent-glands secretion of Graphosoma lineatum adults; (5) hexane as a non-polar solvent and (6) pyrazine: 2-isobutyl-3-methoxypyrazine in experiments with leopard geckos as a positive control for excluding the...Skupina ploštice (Heteroptera) má vynikající schopnost produkovat/uchovávat velké množství chemických látek, jež tvo í základ jejich komplexní repelentní sekrece. Mezi nejlépe prostudované repelentní sekrece pat í sekrece Graphosoma lineatum skládající se z mnoha složek, které mohou p sobit jako iritanty nebo p ímo jako toxiny. Mezi hlavní chemické složky sekrece pat í aldehydy s krátkými et zci. Diserta ní práce se zam uje na hlavní chemické složky této repelentní sekrece - aldehydy - stejn jako na extrahovanou sekreci metathorakálních pachových žláz Graphosoma lineatum. Celkem byly testovány aversivní reakce ty vybraných druh predátor : (1) gekon ík no ní (Eublepharis macularius); (2) ješt rka zelená (Lacerta viridis); (3) sýkora ko adra (Parus major) a (4) sýkora mod inka (Cyanistes caeruleus). Vybrané druhy predátor byly konfrontovány s majoritními složkami obranné sekrece Graphosoma lineatum: (1) sm s t í aldehyd : (E)-hex-2-enal, (E)-oct-2-enal, (E)-dec-2-enal; (2) sm s t chto t í aldehyd obohacená o tridekan; (3) oxoaldehyd: (E)-4-oxohex-2-enal; (4) extrahovaná sekrece metathorakálních pachových žláz dosp lé Graphosoma lineatum; (5) hexan, jakožto nepolární rozpoušt dlo a (6) pyrazín: 2-isobutyl-3-methoxypyrazín u experiment s gekon íky no ními jako pozitivní kontrola k vylou ení efektu...Department of ZoologyKatedra zoologieFaculty of SciencePřírodovědecká fakult
Leonid Kruglyak - One of the best experts on this subject based on the ideXlab platform.
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genetics of white color and iridophoroma in lemon frost leopard geckos
PLOS Genetics, 2021Co-Authors: Longhua Guo, Joshua S Bloom, Steve Sykes, Elaine Huang, Zain Kashif, Elsie Pham, Ana Alcaraz, Xinshu Grace Xiao, Sandra Duartevogel, Leonid KruglyakAbstract:The squamates (lizards and snakes) are close relatives of birds and mammals, with more than 10,000 described species that display extensive variation in a number of important biological traits, including coloration, venom production, and regeneration. Due to a lack of genomic tools, few genetic studies in squamates have been carried out. The leopard gecko, Eublepharis macularius, is a popular companion animal, and displays a variety of coloration patterns. We took advantage of a large breeding colony and used linkage analysis, synteny, and homozygosity mapping to investigate a spontaneous semi-dominant mutation, "Lemon Frost", that produces white coloration and causes skin tumors (iridophoroma). We localized the mutation to a single locus which contains a strong candidate gene, SPINT1, a tumor suppressor implicated in human skin cutaneous melanoma (SKCM) and over-proliferation of epithelial cells in mice and zebrafish. Our work establishes the leopard gecko as a tractable genetic system and suggests that a tumor suppressor in melanocytes in humans can also suppress tumor development in iridophores in lizards.
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genetics of white color and iridophoroma in lemon frost leopard geckos
bioRxiv, 2020Co-Authors: Longhua Guo, Joshua S Bloom, Steve Sykes, Elaine Huang, Zain Kashif, Elsie Pham, Ana Alcaraz, Xinshu Grace Xiao, Sandra Duartevogel, Leonid KruglyakAbstract:Coloration patterns promote survival and reproductive success in the animal kingdom. Despite their importance, wide gaps exist in our understanding of the genetic and evolutionary mechanisms that underpin them. The leopard gecko, Eublepharis macularius, is a popular companion animal, and displays a variety of coloration patterns. We investigated a spontaneous semi-dominant mutation, known as "Lemon Frost", that causes extensive white color in leopard gecko skin. Although "Lemon Frost" individuals are aesthetically appealing, more than 80% of them develop tumors of white color (i.e., iridophoroma) 0.5 to 5 years after birth. To identify the gene that regulates white color and is likely also responsible for the iridophoroma, we genotyped 220 animals, including 33 homozygous mutants, with short-read sequencing. We used synteny, linkage analysis and homozygosity mapping to localize the mutation to a strong candidate gene, SPINT1, a tumor suppressor previously implicated in human skin cutaneous melanoma (SKCM) as well as in over-proliferation of epithelial cells in mice and zebrafish. Our work establishes the leopard gecko as a tractable genetic system and suggests that a tumor suppressor in melanocytes in humans can also suppress tumor development in iridophores in lizards.
Turk Rhen - One of the best experts on this subject based on the ideXlab platform.
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Constraints on temperature-dependent sex determination in the leopard gecko (Eublepharis macularius): response to Kratochvil et al.
Naturwissenschaften, 2008Co-Authors: Victoria Huang, Turk Rhen, Jon T. Sakata, Patricia Coomber, Sarah Simmonds, David CrewsAbstract:Kratochvil et al. (Naturwissenschaften 95:209–215, 2008 ) reported recently that in the leopard gecko ( Eublepharis macularius ) of the family Eublepharidae with temperature-dependent sex determination (TSD), clutches in which eggs were incubated at the same temperature produce only same-sex siblings. Interpreting this result in light of studies of sex steroid hormone involvement in sex determination, they suggested that maternally derived yolk steroid hormones could constrain sex-determining mechanisms in TSD reptiles. We have worked extensively with this species and have routinely incubated clutches at constant temperatures. To test the consistency of high frequency same-sex clutches across different incubation temperatures, we examined our records of clutches at the University of Texas at Austin from 1992 to 2001. We observed that clutches in which eggs were incubated at the same incubation temperature produced mixed-sex clutches as well as same-sex clutches. Furthermore, cases in which eggs within a clutch were separated and incubated at different temperatures produced the expected number of mixed-sex clutches. These results suggest that maternal influences on sex determination are secondary relative to incubation temperature effects.
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Reproductive tradeoffs and yolk steroids in female leopard geckos, Eublepharis macularius
Journal of Evolutionary Biology, 2006Co-Authors: Turk Rhen, David Crews, Albert J. Fivizzani, P. ElfAbstract:Life history theory predicts tradeoffs among reproductive traits, but the physiological mechanisms underlying such tradeoffs remain unclear. Here we examine reproductive tradeoffs and their association with yolk steroids in an oviparous lizard. Female leopard geckos lay two eggs in a clutch, produce multiple clutches in a breeding season, and reproduce for several years. We detected a significant tradeoff between egg size and the number of clutches laid by females during their first two breeding seasons. Total reproductive effort was strongly condition-dependent in the first season, but much less so in the second season. Although these and other tradeoffs were unmistakable, they were not associated with levels of androstenedione, oestradiol, or testosterone in egg yolk. Female condition and egg size, however, were inversely related to dihydrotestosterone (DHT) levels in egg yolk. Finally, steroid levels in egg yolk were not directly related to steroid levels in the maternal circulation when follicles were developing, indicating that steroid transfer to eggs is regulated. These findings suggest that maternal allocation of DHT could mitigate tradeoffs that lead to poor offspring quality (i.e. poor female condition) and small offspring size (i.e. small egg size).
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organization and activation of sexual and agonistic behavior in the leopard gecko Eublepharis macularius
Neuroendocrinology, 2000Co-Authors: Turk Rhen, David CrewsAbstract:Gonadal sex is determined by the temperature experienced during incubation in the leopard gecko (Eublepharis macularius). Furthermore, both factors, incubation temperature and gonad
Longhua Guo - One of the best experts on this subject based on the ideXlab platform.
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genetics of white color and iridophoroma in lemon frost leopard geckos
PLOS Genetics, 2021Co-Authors: Longhua Guo, Joshua S Bloom, Steve Sykes, Elaine Huang, Zain Kashif, Elsie Pham, Ana Alcaraz, Xinshu Grace Xiao, Sandra Duartevogel, Leonid KruglyakAbstract:The squamates (lizards and snakes) are close relatives of birds and mammals, with more than 10,000 described species that display extensive variation in a number of important biological traits, including coloration, venom production, and regeneration. Due to a lack of genomic tools, few genetic studies in squamates have been carried out. The leopard gecko, Eublepharis macularius, is a popular companion animal, and displays a variety of coloration patterns. We took advantage of a large breeding colony and used linkage analysis, synteny, and homozygosity mapping to investigate a spontaneous semi-dominant mutation, "Lemon Frost", that produces white coloration and causes skin tumors (iridophoroma). We localized the mutation to a single locus which contains a strong candidate gene, SPINT1, a tumor suppressor implicated in human skin cutaneous melanoma (SKCM) and over-proliferation of epithelial cells in mice and zebrafish. Our work establishes the leopard gecko as a tractable genetic system and suggests that a tumor suppressor in melanocytes in humans can also suppress tumor development in iridophores in lizards.
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genetics of white color and iridophoroma in lemon frost leopard geckos
bioRxiv, 2020Co-Authors: Longhua Guo, Joshua S Bloom, Steve Sykes, Elaine Huang, Zain Kashif, Elsie Pham, Ana Alcaraz, Xinshu Grace Xiao, Sandra Duartevogel, Leonid KruglyakAbstract:Coloration patterns promote survival and reproductive success in the animal kingdom. Despite their importance, wide gaps exist in our understanding of the genetic and evolutionary mechanisms that underpin them. The leopard gecko, Eublepharis macularius, is a popular companion animal, and displays a variety of coloration patterns. We investigated a spontaneous semi-dominant mutation, known as "Lemon Frost", that causes extensive white color in leopard gecko skin. Although "Lemon Frost" individuals are aesthetically appealing, more than 80% of them develop tumors of white color (i.e., iridophoroma) 0.5 to 5 years after birth. To identify the gene that regulates white color and is likely also responsible for the iridophoroma, we genotyped 220 animals, including 33 homozygous mutants, with short-read sequencing. We used synteny, linkage analysis and homozygosity mapping to localize the mutation to a strong candidate gene, SPINT1, a tumor suppressor previously implicated in human skin cutaneous melanoma (SKCM) as well as in over-proliferation of epithelial cells in mice and zebrafish. Our work establishes the leopard gecko as a tractable genetic system and suggests that a tumor suppressor in melanocytes in humans can also suppress tumor development in iridophores in lizards.