The chemical structure and biological functions of chin gland secretions were examined in a group of captive desert tortoises, Gopherus agassizii, housed at the Desert Tortoise Conservation Center near Las Vegas, Nevada. Monthly measurements of the chin glands of 20 adult males were made over one year. Gland volume varied seasonally, reaching a maximum in late summer. The chin glands of socially dominant males tended to be larger than those of socially subordinate males. Among all males, there was a positive correlation between plasma testosterone levels and size of the chin glands. Behavioral experiments demonstrated that tortoises of both sexes discriminate the chin gland secretions of familiar males from those of unfamiliar males, suggesting that chin gland secretions may function in conspecific recognition. Electrophoretic studies of chin gland secretions revealed the presence of 12-17 protein components ranging in size from 25,000115,000 Daltons. Although banding patterns among males were very similar, slight individual differences existed in the number and size of high molecular weight protein components.
{"title":"Studies on the Chemistry and Social Significance of Chin Gland Secretions in the Desert Tortoise, Gopherus agassizii","authors":"A. Alberts, D. Rostal, V. Lance","doi":"10.2307/1467075","DOIUrl":"https://doi.org/10.2307/1467075","url":null,"abstract":"The chemical structure and biological functions of chin gland secretions were examined in a group of captive desert tortoises, Gopherus agassizii, housed at the Desert Tortoise Conservation Center near Las Vegas, Nevada. Monthly measurements of the chin glands of 20 adult males were made over one year. Gland volume varied seasonally, reaching a maximum in late summer. The chin glands of socially dominant males tended to be larger than those of socially subordinate males. Among all males, there was a positive correlation between plasma testosterone levels and size of the chin glands. Behavioral experiments demonstrated that tortoises of both sexes discriminate the chin gland secretions of familiar males from those of unfamiliar males, suggesting that chin gland secretions may function in conspecific recognition. Electrophoretic studies of chin gland secretions revealed the presence of 12-17 protein components ranging in size from 25,000115,000 Daltons. Although banding patterns among males were very similar, slight individual differences existed in the number and size of high molecular weight protein components.","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467075","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68499341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. C. Zimmerman, M. O’connor, S. Bulova, J. Spotila, S. Kemp, C. Salice
We monitored meteorological variables, daily and seasonal patterns of body tem- perature, corresponding operative temperatures, and microhabitat utilization by desert tortoises (Gopherus agassizii) during the 1991 and 1992 activity seasons of tortoises in the eastern Mojave desert. We studied tortoises in enclosures of natural habitat at the Desert Tortoise Conservation Center (DTCC) near Las Vegas, Nevada and a population of free-ranging tortoises in a field site adjacent to the DTCC. Air, ground and operative temperatures coincided with daily and monthly patterns of incident solar radiation. Variation in body temperature was primarily a consequence of microhabitat selection, principally use of burrows. During July-October, in the morning, body temperatures of tortoises in burrows were cooler than those of individuals on the surface. During midday, tortoises remained in burrows where body temperatures were cooler than extreme surface operative temperatures. While tortoises remained in burrows during much of the day, tortoises typically did not sleep in burrows at night. Microhabitat utilization was dictated by avoidance of extreme temperatures during midday, and microhabitat selection corresponded qualitatively to maintenance of energy and water balances. Effective conservation efforts to preserve habitat of desert tortoises will focus upon managing variables associated with integrity of burrows. ulation
{"title":"THERMAL ECOLOGY OF DESERT TORTOISES IN THE EASTERN MOJAVE DESERT: SEASONAL PATTERNS OF OPERATIVE AND BODY TEMPERATURES, AND MICROHABITAT UTILIZATION","authors":"L. C. Zimmerman, M. O’connor, S. Bulova, J. Spotila, S. Kemp, C. Salice","doi":"10.13016/M2M84H","DOIUrl":"https://doi.org/10.13016/M2M84H","url":null,"abstract":"We monitored meteorological variables, daily and seasonal patterns of body tem- perature, corresponding operative temperatures, and microhabitat utilization by desert tortoises (Gopherus agassizii) during the 1991 and 1992 activity seasons of tortoises in the eastern Mojave desert. We studied tortoises in enclosures of natural habitat at the Desert Tortoise Conservation Center (DTCC) near Las Vegas, Nevada and a population of free-ranging tortoises in a field site adjacent to the DTCC. Air, ground and operative temperatures coincided with daily and monthly patterns of incident solar radiation. Variation in body temperature was primarily a consequence of microhabitat selection, principally use of burrows. During July-October, in the morning, body temperatures of tortoises in burrows were cooler than those of individuals on the surface. During midday, tortoises remained in burrows where body temperatures were cooler than extreme surface operative temperatures. While tortoises remained in burrows during much of the day, tortoises typically did not sleep in burrows at night. Microhabitat utilization was dictated by avoidance of extreme temperatures during midday, and microhabitat selection corresponded qualitatively to maintenance of energy and water balances. Effective conservation efforts to preserve habitat of desert tortoises will focus upon managing variables associated with integrity of burrows. ulation","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66548301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Comparative Anatomy and Phylogeny of the Cloacae of Salamanders (Amphibia: Caudata). VII. Plethodontidae","authors":"D. Sever","doi":"10.2307/1467083","DOIUrl":"https://doi.org/10.2307/1467083","url":null,"abstract":"","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467083","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68499669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Ruby, L. C. Zimmerman, S. Bulova, C. Salice, M. O’connor, J. Spotila
We tested the effect of water stress on behavior of desert tortoises in semi-natural enclosures. Populations of adult and immature desert tortoises were established at relatively high density in 4.1 ha pens at the Desert Tortoise Conservation Center near Las Vegas, Nevada. Pairs of pens received different levels of food (sod and forb patches) and water supplementation. We postulated that the relatively high densities of tortoises and the different levels of resources created different levels of environmental stress on the populations. Behavior was systematically observed during June-August 1991 and April-September 1992 for differences due to treatment (food and water supplementation versus no food and water supplementation). Behavioral observations were collected during 30 minute focal periods and periodic scan censuses of pens. Animals in the unsupplemented treatments, particularly males, moved further during focal periods than animals with supplemented diets. Movement varied significantly among months. There were no differences in feeding rates among treatments, although monthly effects were important in both treatments. Some differences between years in feeding rates appear related to rainfall patterns and presumably changes in resource availability. Interactions among animals were highest in May and September and were more frequent in unsupplemented pens. Length of morning activity period was shorter in unsupplemented pens for all months. Within treatments, supplemented females were more visible and were seen for longer periods of time during a morning activity period. Home ranges were not significantly different between treatments but showed significant sex effects. Males have larger home ranges than females, and both have larger home ranges than immature animals. When stressed by lack of water and food resources, tortoises reduced the length of above-ground activity time but attempted to compensate for this decreased time by increasing amounts of movement and feeding while active.
{"title":"BEHAVIORAL RESPONSES AND TIME ALLOCATION DIFFERENCES IN DESERT TORTOISES EXPOSED TO ENVIRONMENTAL STRESS IN SEMI-NATURAL ENCLOSURES","authors":"D. Ruby, L. C. Zimmerman, S. Bulova, C. Salice, M. O’connor, J. Spotila","doi":"10.2307/1467068","DOIUrl":"https://doi.org/10.2307/1467068","url":null,"abstract":"We tested the effect of water stress on behavior of desert tortoises in semi-natural enclosures. Populations of adult and immature desert tortoises were established at relatively high density in 4.1 ha pens at the Desert Tortoise Conservation Center near Las Vegas, Nevada. Pairs of pens received different levels of food (sod and forb patches) and water supplementation. We postulated that the relatively high densities of tortoises and the different levels of resources created different levels of environmental stress on the populations. Behavior was systematically observed during June-August 1991 and April-September 1992 for differences due to treatment (food and water supplementation versus no food and water supplementation). Behavioral observations were collected during 30 minute focal periods and periodic scan censuses of pens. Animals in the unsupplemented treatments, particularly males, moved further during focal periods than animals with supplemented diets. Movement varied significantly among months. There were no differences in feeding rates among treatments, although monthly effects were important in both treatments. Some differences between years in feeding rates appear related to rainfall patterns and presumably changes in resource availability. Interactions among animals were highest in May and September and were more frequent in unsupplemented pens. Length of morning activity period was shorter in unsupplemented pens for all months. Within treatments, supplemented females were more visible and were seen for longer periods of time during a morning activity period. Home ranges were not significantly different between treatments but showed significant sex effects. Males have larger home ranges than females, and both have larger home ranges than immature animals. When stressed by lack of water and food resources, tortoises reduced the length of above-ground activity time but attempted to compensate for this decreased time by increasing amounts of movement and feeding while active.","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68498799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A behavioral inventory of the desert tortoise was compiled from observations on confined tortoises in experimental pens and free-ranging tortoises within semi-natural enclosures. We describe 80 actions. Much of a tortoise's active time outside burrows is spent in feeding behavior. Display sequences have both visual and olfactory components. Aggressive and courtship sequences have similar beginnings but proceed differently as animals respond to each other. Aggressive behavior involves much headbobbing, sniffing, biting and ramming. A pushing match enables tortoises to assess body mass and determine dominance. Courtship behavior may involve trailing, circling of the female by the male, and biting and sniffing sequences before mounting. There is no rejection display by females of courting males. Comparisons between Gopherus species and related tortoise groups suggest a very conservative evolution of behavior within the Gopherus group.
{"title":"A Behavioral Inventory of the Desert Tortoise: Development of an Ethogram","authors":"D. Ruby, H. Niblick","doi":"10.2307/1467073","DOIUrl":"https://doi.org/10.2307/1467073","url":null,"abstract":"A behavioral inventory of the desert tortoise was compiled from observations on confined tortoises in experimental pens and free-ranging tortoises within semi-natural enclosures. We describe 80 actions. Much of a tortoise's active time outside burrows is spent in feeding behavior. Display sequences have both visual and olfactory components. Aggressive and courtship sequences have similar beginnings but proceed differently as animals respond to each other. Aggressive behavior involves much headbobbing, sniffing, biting and ramming. A pushing match enables tortoises to assess body mass and determine dominance. Courtship behavior may involve trailing, circling of the female by the male, and biting and sniffing sequences before mounting. There is no rejection display by females of courting males. Comparisons between Gopherus species and related tortoise groups suggest a very conservative evolution of behavior within the Gopherus group.","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467073","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68499283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gerrhonotus liocephalus is demonstrated to consist of at least three species rather than the single polytypic species currently recognized. Of the seven currently recognized subspecies, G. 1. aguayoi, G. 1, infernalis and G. 1. taylori become G. infernalis; G. 1. ophiurus and G. 1, loweryi become G . ophiurus; and G . 1, austrinus and G . 1. liocephalus retain the name G . liocephalus. No subspecies are recognized within any of these three species. Certain populations from western Mexico (Durango, Sinaloa, Jalisco, and Colima) remain of uncertain identity, but are tentatively referred to as G . cf, liocephalus. Evidence for these conclusions is derived from an analysis of scalation, coloration, and morphometric variation. The taxonomic history in Gerrhonotus also is discussed
{"title":"Species Limits in the Genus Gerrhonotus (Squamata: Anguidae)","authors":"D. A. Good","doi":"10.2307/1467080","DOIUrl":"https://doi.org/10.2307/1467080","url":null,"abstract":"Gerrhonotus liocephalus is demonstrated to consist of at least three species rather than the single polytypic species currently recognized. Of the seven currently recognized subspecies, G. 1. aguayoi, G. 1, infernalis and G. 1. taylori become G. infernalis; G. 1. ophiurus and G. 1, loweryi become G . ophiurus; and G . 1, austrinus and G . 1. liocephalus retain the name G . liocephalus. No subspecies are recognized within any of these three species. Certain populations from western Mexico (Durango, Sinaloa, Jalisco, and Colima) remain of uncertain identity, but are tentatively referred to as G . cf, liocephalus. Evidence for these conclusions is derived from an analysis of scalation, coloration, and morphometric variation. The taxonomic history in Gerrhonotus also is discussed","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467080","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68499418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We conducted tests on the behavioral responses of captive desert tortoises (Gopherus agassizii) to barriers and highway obstacles. Desert tortoises are slow-moving but persistent wan- derers in their natural habitat. Consequently, they move substantial distances when they meet a barrier that they cannot go around. Tortoises responded differently to solid and non-solid barriers when placed in small pens constructed of various materials. Our tests indicated that a screen mesh with small enough openings to exclude a tortoise's head was the most suitable barrier material. When tortoises were tested for 2 h periods or after an overnight stay in a barrier pen, rates of responses with barriers declined with time but tortoises continued movement along the barrier. In a choice situation, we found no preference by tortoises for following either solid or mesh barrier fences. Tortoises quickly walked past openings in a barrier which were too small to enter but easily escaped from a barrier pen within 30 min when openings of an appropriate size were available. We found tortoises willingly entered culverts under large highways and retreated from concrete highways barriers.
{"title":"BEHAVIORAL RESPONSES TO BARRIERS BY DESERT TORTOISES: IMPLICATIONS FOR WILDLIFE MANAGEMENT","authors":"D. Ruby, J. Spotila, S. K. Martin, S. Kemp","doi":"10.13016/M2R27T","DOIUrl":"https://doi.org/10.13016/M2R27T","url":null,"abstract":"We conducted tests on the behavioral responses of captive desert tortoises (Gopherus agassizii) to barriers and highway obstacles. Desert tortoises are slow-moving but persistent wan- derers in their natural habitat. Consequently, they move substantial distances when they meet a barrier that they cannot go around. Tortoises responded differently to solid and non-solid barriers when placed in small pens constructed of various materials. Our tests indicated that a screen mesh with small enough openings to exclude a tortoise's head was the most suitable barrier material. When tortoises were tested for 2 h periods or after an overnight stay in a barrier pen, rates of responses with barriers declined with time but tortoises continued movement along the barrier. In a choice situation, we found no preference by tortoises for following either solid or mesh barrier fences. Tortoises quickly walked past openings in a barrier which were too small to enter but easily escaped from a barrier pen within 30 min when openings of an appropriate size were available. We found tortoises willingly entered culverts under large highways and retreated from concrete highways barriers.","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66548678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The seasonal reproductive cycles of male and female desert tortoises (Gopherus agassizii) were studied under semi-natural conditions. Tortoises were maintained in outdoor pens subject to ambient weather conditions and received supplemental food and water. Heparinized blood samples were collected monthly using jugular puncture. Ovarian follicular growth and egg development were monitored using ultrasonography. Mating was observed in the fall (following nesting) and the spring (prior to nesting). Vitellogenesis occurred during the fall prior to hibernation. Nesting was observed from May-early July with females producing one or two clutches. Clutches ranged from 2-7 eggs. Both males and females displayed seasonal testosterone cycles.
{"title":"Seasonal Reproductive Cycle of the Desert Tortoise (Gopherus agassizii) in the Eastern Mojave Desert","authors":"D. Rostal, V. Lance, J. S. Grumbles, A. Alberts","doi":"10.2307/1467071","DOIUrl":"https://doi.org/10.2307/1467071","url":null,"abstract":"The seasonal reproductive cycles of male and female desert tortoises (Gopherus agassizii) were studied under semi-natural conditions. Tortoises were maintained in outdoor pens subject to ambient weather conditions and received supplemental food and water. Heparinized blood samples were collected monthly using jugular puncture. Ovarian follicular growth and egg development were monitored using ultrasonography. Mating was observed in the fall (following nesting) and the spring (prior to nesting). Vitellogenesis occurred during the fall prior to hibernation. Nesting was observed from May-early July with females producing one or two clutches. Clutches ranged from 2-7 eggs. Both males and females displayed seasonal testosterone cycles.","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467071","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68499125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reproductive characteristics and lipid cycles of two tropical populations of the insectivorous lizard Sceloporus variabilis inhabiting different elevations were compared. Compared to phylogenetically related temperate zone species, S. variabilis demonstrates reproductive characteristics predicted in the literature for lizards inhabiting relatively aseasonal environments: small clutch size (4.3-4.6) relative to body size (60-61 mm SVL), highest clutch frequency (4.5-6), earliest age at maturity (4-7 months), longest reproductive season (8-9.5 months) and smaller relative clutch mass (0.203-0.212). Most of these trends are also found in the comparison of lizards from the high elevation population (1000 m above sea level), where seasonality is more conspicuous, with lizards from the low elevation population (45 m above sea level) where the environment is more equable. At low elevation, the reproductive season is longer, permitting reproductive potential to be higher. In addition, incubation time of eggs is shorter at low elevation and thus, some females are able to reproduce at the end of the same reproductive season in which they were born. Seasonal shifts in egg size in the high elevation population are analyzed regarding the bet-hedging and the parental investment models. Lizards at both elevations store lipids in fat bodies and in body tissues that are used at the beginning of the reproductive season. Higher and more suitable ambient temperature and abundant food later in the reproductive season allow lizards to get the energy necessary for reproduction directly from the environment, until the "nortes" (northern storms) season restricts lizard activity. Juveniles use all energy from food for growth and do not store lipids until shortly before reaching maturity.
比较了不同海拔地区热带食虫蜥蜴Sceloporus variabilis的生殖特征和脂质循环。与系统发育相关的温带物种相比，变异蜥蜴表现出了文献中预测的相对季节性环境蜥蜴的生殖特征:相对于体型(60-61 mm SVL)，最小的产蛋数(4.3-4.6)，最高的产蛋频率(4.5-6)，最早的成熟年龄(4-7个月)，最长的繁殖季节(8-9.5个月)和较小的相对产蛋质量(0.203-0.212)。在高海拔种群(海拔1000米以上)和低海拔种群(海拔45米以上)的蜥蜴之间的比较中也发现了这些趋势，高海拔种群(海拔1000米以上)的季节性更为明显，而低海拔种群(海拔45米以上)的环境更为平等。在低海拔地区，繁殖季节较长，因此繁殖潜力较高。此外，在低海拔地区，卵的孵化时间较短，因此，一些雌性能够在它们出生的同一繁殖季节结束时繁殖。利用投注对冲模型和亲本投资模型分析了高海拔种群卵大小的季节变化。在这两个海拔高度的蜥蜴将脂肪储存在脂肪体和身体组织中，在繁殖季节开始时使用。在繁殖季节后期，更高、更适宜的环境温度和丰富的食物使蜥蜴能够直接从环境中获得繁殖所需的能量，直到“北方风暴”季节限制了蜥蜴的活动。幼鱼利用食物中的所有能量来生长，直到成年前不久才储存脂质。
{"title":"Reproduction and Lipid Utilization of Tropical Populations of Sceloporus variabilis","authors":"M. Benabib","doi":"10.2307/1467079","DOIUrl":"https://doi.org/10.2307/1467079","url":null,"abstract":"Reproductive characteristics and lipid cycles of two tropical populations of the insectivorous lizard Sceloporus variabilis inhabiting different elevations were compared. Compared to phylogenetically related temperate zone species, S. variabilis demonstrates reproductive characteristics predicted in the literature for lizards inhabiting relatively aseasonal environments: small clutch size (4.3-4.6) relative to body size (60-61 mm SVL), highest clutch frequency (4.5-6), earliest age at maturity (4-7 months), longest reproductive season (8-9.5 months) and smaller relative clutch mass (0.203-0.212). Most of these trends are also found in the comparison of lizards from the high elevation population (1000 m above sea level), where seasonality is more conspicuous, with lizards from the low elevation population (45 m above sea level) where the environment is more equable. At low elevation, the reproductive season is longer, permitting reproductive potential to be higher. In addition, incubation time of eggs is shorter at low elevation and thus, some females are able to reproduce at the end of the same reproductive season in which they were born. Seasonal shifts in egg size in the high elevation population are analyzed regarding the bet-hedging and the parental investment models. Lizards at both elevations store lipids in fat bodies and in body tissues that are used at the beginning of the reproductive season. Higher and more suitable ambient temperature and abundant food later in the reproductive season allow lizards to get the energy necessary for reproduction directly from the environment, until the \"nortes\" (northern storms) season restricts lizard activity. Juveniles use all energy from food for growth and do not store lipids until shortly before reaching maturity.","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/1467079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68499198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Spotila, L. C. Zimmerman, Christopher A. Binckley, J. S. Grumbles, D. Rostal, A. List, E. C. Beyer, Kelly M. Phillips, S. Kemp
Incubation temperature has a direct effect on sex determination of the desert tortoise. Low temperatures (26.0-30.6 C) produce males and high temperatures (32.8-35.3 C) produce females. Pivotal temperature is approximately 31.8 C. Macroscopic and microscopic anatomy of the gonads is similar to that of other turtles. Hatching success and survival is very good between 28.1 and 32.8 C in dry sand (-5000 kPa). Incubation at 35.3 C is lethal for 72% of the eggs and produces weak hatchlings that die within 45 days. Wet sand (-5 kPa) is lethal for desert tortoise eggs. Hatchling size was dependent upon egg size and incubation condition. Hatchlings from eggs incubated at 32.8 and 35.3 C were significantly smaller than hatchlings from eggs incubated at 28.1 and 30.6 C. Hatching mass had no effect on growth rate of hatchlings. Thus, large eggs produced large hatchlings that were larger than their siblings at 120 days of age. Hatchlings from
{"title":"EFFECTS OF INCUBATION CONDITIONS ON SEX DETERMINATION, HATCHING SUCCESS, AND GROWTH OF HATCHLING DESERT TORTOISES, GOPHERUS AGASSIZII","authors":"J. Spotila, L. C. Zimmerman, Christopher A. Binckley, J. S. Grumbles, D. Rostal, A. List, E. C. Beyer, Kelly M. Phillips, S. Kemp","doi":"10.13016/M2GK2M","DOIUrl":"https://doi.org/10.13016/M2GK2M","url":null,"abstract":"Incubation temperature has a direct effect on sex determination of the desert tortoise. Low temperatures (26.0-30.6 C) produce males and high temperatures (32.8-35.3 C) produce females. Pivotal temperature is approximately 31.8 C. Macroscopic and microscopic anatomy of the gonads is similar to that of other turtles. Hatching success and survival is very good between 28.1 and 32.8 C in dry sand (-5000 kPa). Incubation at 35.3 C is lethal for 72% of the eggs and produces weak hatchlings that die within 45 days. Wet sand (-5 kPa) is lethal for desert tortoise eggs. Hatchling size was dependent upon egg size and incubation condition. Hatchlings from eggs incubated at 32.8 and 35.3 C were significantly smaller than hatchlings from eggs incubated at 28.1 and 30.6 C. Hatching mass had no effect on growth rate of hatchlings. Thus, large eggs produced large hatchlings that were larger than their siblings at 120 days of age. Hatchlings from","PeriodicalId":56309,"journal":{"name":"Herpetological Monographs","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66547736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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