Geographic and Annual Variation in Life-History Traits in a Temperate Zone Australian Skink

Wapstra, Erik; Swain, Roy

doi:10.2307/1566108

Cited by 51 publications

(39 citation statements)

References 57 publications

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“…This finding is not in accordance with the prediction from intraspecific comparisons of species with wide geographic ranges that larger offspring should be produced in colder localities (Parker and Begon, 1986;Forsman and Shine, 1995;Mathies and Andrews, 1995;Rohr, 1997;Wapstra and Swain, 2001;Ji et al, 2002). Why do females of P. korros from the CZ and DH populations not differ in population egg mass?…”

Section: Discussioncontrasting

confidence: 61%

Reproductive traits of the gray ratsnake Ptyas korros from three geographically distinct populations

Mao

Chen

et al. 2012

Current Zoology

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We collected gravid gray rat snakes Ptyas korros from three geographically distinct populations in China, Chenzhou (CZ), Jiangshan (JS) and Dinghai (DH), to study geographical variation in female reproductive traits. Egg-laying dates differed among the three populations such that at the most northern latitude egg-laying was latest, and earliest at the most southern latitutde. Clutch size, clutch mass, egg mass, egg shape, within clutch variability in egg sizes and relative clutch mass differed among the three populations, whereas post-oviposition body mass did not. Except for egg-laying date, none of the traits examined varied in a geographically continuous trend. CZ and DH females, although separated by a distance of approximately 1100 km as the crow flies, were similar in nearly all traits examined. JS females were distinguished from CZ and DH females by their higher fecundity (clutch size), greater reproductive output (clutch mass) and more rounded eggs. Our data do not validate the prediction that larger offspring should be produced in colder localities. The absence of an egg size-number trade-off in each of the three populations presumably suggests that P. korros is among species where eggs are well optimized for size within a population [Current Zoology 58 (6): 820-827, 2012].

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Section: Discussioncontrasting

confidence: 61%

Reproductive traits of the gray ratsnake Ptyas korros from three geographically distinct populations

Mao

Chen

et al. 2012

Current Zoology

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“…Palpation of the abdomen can be used to detect follicular development, ovulation, and pregnancy in reptiles [Cree et al, 1991;DeNardo, 1996;Wapstra and Swain, 2001]. Follicles are reported as firm, spherical structures that can be differentiated from the softer embryos.…”

Section: Discussionmentioning

confidence: 99%

“…Similar constraints to ultrasound occur in some species (e.g., tuatara) because their ribs extend along the abdominal cavity [Cree at al., 1991]. Palpation has been used to assess the number of embryos in small skinks [Olsson et al, 1993;Wapstra and Swain, 2001] but is unreliable in larger lizards and does not allow any assessment of embryonic development or viability [DeNardo, 1996]. Palpation was effective in our animals as they were docile and easily handled, but would be much less effective in tense or larger viviparous reptiles.…”

Section: Discussionmentioning

confidence: 99%

Comparison of noninvasive methods for the evaluation of female reproductive condition in a large viviparous lizard, Tiliqua nigrolutea

et al. 2002

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We compared the diagnostic value of three noninvasive methods (radiography, ultrasound, and palpation) of evaluating reproductive status in females of a large viviparous skink, the blotched blue-tongued lizard (Tiliqua nigrolutea). Radiography could be used to identify postovulatory females during the periovulatory period. However, in early to mid-gestation, radiography did not allow differentiation of the relatively homogenous structures within the abdomen. In late gestation, once calcification of the embryonic skeleton had occurred, gestation could be diagnosed and embryos counted. Ultrasound allowed differentiation between preovulatory, postovulatory, and nonreproductive females during the periovulatory period. Ultrasound also allowed visualisation of follicles during the early and middle stages of gestation. However, the level of operator experience, and the misdiagnosis of artefacts limited the accuracy of diagnosis. In the later stages of gestation, ultrasound did allow the detection of identifiable features of the developing foetal unit (fluid-filled foetal membranes, independent movement of the embryo, and visualisation of the heartbeat). Colour Doppler imaging could be used to visualise embryonic blood flow. Ultrasonography was not useful in detecting the number of embryos present. Palpation during the periovulatory period could be used to detect follicles and determine whether ovulation had occurred. However, during the remainder of the gestation period, palpation was unable to differentiate reproductive condition. This study provides a basis for the diagnosis of reproductive condition and problems in viviparous reptiles. Each of the diagnostic techniques is useful at different stages of gestation, and the use of a combined approach will give the most information throughout the reproductive cycle.

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“…Daily and seasonal patterns of environmental temperature affect profiles of body temperatures in both thermoregulators and thermoconformers. Consequently, thermal environments determine the duration and effectiveness of foraging (Grant and Dunham 1990;Ayers and Shine 1997;Wapstra and Swain 2001), consumption and assimilation (Ji et al 1995;Kingsolver and Woods 1997;Angilletta 2001). These thermal constraints on behavioral and physiological processes generate latitudinal and altitudinal variation in the growth, development, and maturation of ectotherms (Beaupre 1995;Niewiarowski 2001;Sears and Angilletta 2004).…”

mentioning

confidence: 99%

CONVERGENT EVOLUTION OF EMBRYONIC GROWTH AND DEVELOPMENT IN THE EASTERN FENCE LIZARD (SCELOPORUS UNDULATUS)

Oufiero

Angilletta

2006

Evolution

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Abstract. Theory predicts that cold environments will select for strategies that enhance the growth of ectotherms, such as early emergence from nests and more efficient use of resources. We used a common garden experiment to detect parallel clines in rates of embryonic growth and development by eastern fence lizards (Sceloporus undulatus). Using realistic thermal conditions, we measured growth efficiencies and incubation periods of lizards from five populations representing two distinct clades. In both clades, embryos from cold environments (Indiana, New Jersey, and Virginia) grew more efficiently and hatched earlier than embryos from warm environments (Florida and South Carolina). Because eggs from cold environments were larger than eggs from warm environments, we experimentally miniaturized eggs from one population (Virginia) to determine whether rapid growth and development were caused by a greater maternal investment. Embryos in miniaturized eggs grew as efficiently and incubated for the same duration as embryos in unmanipulated eggs. Taken together, our results suggest countergradient variation has evolved at least twice in S. undulatus.

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Geographic and Annual Variation in Life-History Traits in a Temperate Zone Australian Skink

Cited by 51 publications

References 57 publications

Reproductive traits of the gray ratsnake Ptyas korros from three geographically distinct populations

Reproductive traits of the gray ratsnake Ptyas korros from three geographically distinct populations

Comparison of noninvasive methods for the evaluation of female reproductive condition in a large viviparous lizard, Tiliqua nigrolutea

CONVERGENT EVOLUTION OF EMBRYONIC GROWTH AND DEVELOPMENT IN THE EASTERN FENCE LIZARD (SCELOPORUS UNDULATUS)

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