Maternal Snout-vent Length Research Articles

Reproductive Traits of Dusky Rattlesnakes (Crotalus triseriatus) in Central Mexico

Abstract Reproductive aspects of most snake species remain elusive because of secretive habits or rarity. Here, we report data on litters of Crotalus triseriatus from two populations in central Mexico. We made 4-d visits to both study sites every other week from April to June during 2014 and 2015 (Site 1) and during 2015 (Site 2). Surveys were made from 0900 to 1800 h to catch as many gravid females as possible. All adult females were maintained in captivity until parturition. We recorded a total of 16 litters (10 from Site 1 and six from Site 2). Average litter size was 7.2 ± 2.2 (n = 13), higher than previously reported in the species. We found no relationship between maternal snout–vent length (SVL) and litter size, and litter size did not differ between study sites or years. In contrast with other studies, we found no relationship between neonate SVL, body mass, and litter size or between maternal and neonatal traits. Dusky Rattlesnakes demonstrate a plastic reproductive response to changing environme...

Selection for increased maternal body volume does not differ between two Scincella lizards with different reproductive modes

Body size and shape are among the most important determinants of reproductive output in diverse animal taxa. We compared morphology and reproductive output between two Scincella lizards (Scincidae), Scincella modesta (oviparous) and Scincella reevesii (viviparous), to examine whether viviparous females compensate for their lower reproductive output by modifying maternal body size and/or shape. As predicted, reproductive output was lower in S. reevesii than in S. modesta when corrected for body size. The two lizards differed morphologically, but were similar in three aspects: females were the larger sex, the relative head size was greater in adult males, and the relative abdomen size was greater in adult females. Sexual dimorphism in abdomen length (AL) was more evident in S. reevesii than in S. modesta, but this difference was attributable to a smaller sexual difference in AL in S. modesta, rather than to the greater relative maternal AL in S. reevesii. Female S. reevesii on average were larger than female S. modesta in snout–vent length (SVL), but this increase in overall body size cannot be viewed as a way of allowing female S. reevesii to compensate for lower reproductive output, as the linear slope of reproductive output against maternal SVL did not differ between the two species. Our data show that selection for increased maternal body volume does not differ between the two Scincella lizards with different reproductive modes.

Sexual size dimorphism and female reproduction in the white-striped grass lizard Takydromus wolteri

Abstract Sexual size dimorphism (SSD) has long attracted the attention of biologists, and life-history variation is thought to play an important role in the evolution of SSD. Here we quantified SSD and female reproductive traits to identify potential associations between SSD and female reproduction in the white-striped grass lizard Takydromus wolteri. In a population from Chuzhou, China, the largest male and female were 53.0 mm and 57.5 mm in snout-vent length (SVL), respectively. Females were larger in SVL and abdomen length, whereas males were larger in head size and tail length. Females produced up to five clutches of eggs during the breeding season, with large females producing more clutches and more eggs per clutch than small ones. As a result, large females had a higher annual fecundity and reproductive output. Egg size was positively correlated with maternal SVL in the first clutch, but not in subsequent clutches. These results suggest that T. wolteri is a species with female-biased SSD, and that fecundity selection, in which large females have higher fecundity due to their higher capacity for laying eggs, is likely correlated with the evolution of SSD in this species [Current Zoology 58 (2): 236–243, 2012].

Natural history of the slaty grey snake (Stegonotus cucullatus) (Serpentes:Colubridae) from tropical north Queensland, Australia

Slaty grey snakes (Stegonotus cucullatus) are medium to large members of the Colubridae that are common throughout the eastern and northern tropics of Australia. Although intensive field studies have been conducted on populations in the Northern Territory for over 10 years, no ecological data have been presented on free-ranging specimens of populations inhabiting tropical north Queensland. During a 10-year period we collected opportunistic data on 120 free-ranging specimens from the seasonally Wet Tropics in north Queensland. These snakes provided data on body sizes, activity times, food habits and reproduction. Male S. cucullatus were larger than females and had larger heads. More snakes were found during the warmer, humid parts of the year (wet season). S. cucullatus ate a wide range of vertebrate prey, including reptile eggs that were obtained seasonally. Females produced one clutch per year, and no relationship was found between maternal snout–vent length and clutch size.

Female life‐history characteristics of the Mosor rock lizard, Dinarolacerta mosorensis (Kolombatović, 1886) from Montenegro (Squamata: Lacertidae)

Analysis of the female life history of the poorly studied endemic Balkan lizard species Dinarolacerta mosorensis was conducted on three population samples from Montenegro. One clutch is produced annually. Females mature at body sizes of 56–57 mm snout–vent length (SVL), attained at age 3–4 years. SVL increases with age. The average clutch size ranged from 4.3 to 5.2 eggs, and was significantly positively correlated with maternal SVL in two population samples. There were no trade‐offs between egg size/offspring size and clutch size, nor between variation in egg size/offspring size and maternal SVL. The incubation period averaged 26.5 days, while hatching success in captivity was 72%. Significant positive correlations were found between the hatchling mass and egg mass and size, and also between the hatchling total length and egg width and volume. There was a significant negative relationship between the hatchling mass and incubation duration.

Ecology of Wahlberg’s velvet gecko, Homopholis wahlbergii, in southern Africa

We examined 170 museum specimens of the southern African gekkonid lizard Homopholis wahlbergii, to quantify sexual dimorphism, male and female reproductive cycles and diet. The largest male and female we recorded were 116 and 119 mm snout–vent length (SVL) respectively. We compared SVL, tail length, head length, head width and eye diameter and found no evidence of sexual dimorphism in any of these characters. The smallest female with thickened muscular oviducts and follicles, indicating sexual maturity, was 59 mm SVL, but the smallest female we found with fully developed eggs was 85mmSVL. Virtually all females larger than 59 mm appeared to be in some stage of reproduction, suggesting that females reproduce every year once they reach sexual maturity. Egg size ranged from 17–19mm long. Egg size was not correlated with maternal SVL. We found adult females with ready-to-lay eggs during the warmer months of the year, but not during winter and spring. The smallest sexually mature male was 72 mm SVL. Virtually all males larger than this size displayed at least semi-turgid testes and most adult male testes were at least semi-turgid for much of the year. The only significant decrease in testicular activity was in mid-winter (June–August), thus, spermatogenesis is closely tied to female follicular development and ovulation. Velvet geckos are largely insectivorous (92%) and feed on a broad spectrum of prey. Their diet was dominated both numerically (34%) and volumetrically (22%) by beetles. Lepidoptera were the next most important prey category, suggesting that they exploit both terrestrial and flying invertebrates. They are unusual among lizards because they feed on millipedes. Males and females had very similar diets which may be explained by their lack of sexual dimorphism, although females tended to eat a greater volume of prey. Interestingly, less than half (37%) of the lizards examined contained prey items, suggesting that most individuals were not in positive energy balance. We also found evidence of prey size selection as a function of gape size, such that larger geckos took advantage of larger prey items.

Ecology of Wahlberg's velvet gecko, Homopholis wahlbergii, in southern Africa

ABSTRACT We examined 170 museum specimens of the southern African gekkonid lizard Homopholis wahlbergii, to quantify sexual dimorphism, male and female reproductive cycles and diet. The largest male and female we recorded were 116 and 119 mm snout–vent length (SVL) respectively. We compared SVL, tail length, head length, head width and eye diameter and found no evidence of sexual dimorphism in any of these characters. The smallest female with thickened muscular oviducts and follicles, indicating sexual maturity, was 59 mm SVL, but the smallest female we found with fully developed eggs was 85 mm SVL. Virtually all females larger than 59 mm appeared to be in some stage of reproduction, suggesting that females reproduce every year once they reach sexual maturity. Egg size ranged from 17–19 mm long. Egg size was not correlated with maternal SVL. We found adult females with ready-to-lay eggs during the warmer months of the year, but not during winter and spring. The smallest sexually mature male was 72 mm SVL....

Life history and reproductive ecology of White's skink, Egernia whitii

The life history and reproductive ecology of White’s skink, Egernia whitii, was examined in a population in the Australian Capital Territory using both field and genetic studies. Colour pattern polymorphism was evident within the population, with both patterned and plain-back morphs present. Lizards typically took 3 years to reach sexual maturity, with the size at maturity being ~75 mm snout–vent length (SVL) in both sexes. There was an even overall adult sex ratio, although a slight female-bias was evident in plain-back individuals. Sexual dimorphism was evident, with males having longer and wider heads, and females having larger body size. Females generally bred annually, with mating occurring in September–October and parturition in late January–February, although the litter was produced over several days (2–10 days, mean 4 days). Litter size ranged from one to four (mean of 2.5). There was a significant relationship between maternal SVL and both litter size and relative clutch mass, but these trends were not consistent between colour morphs. An inverse relationship between litter size and offspring size (SVL and mass) was found. Comparison of the results with previous investigations of E. whitii indicates substantial geographic variation in life-history traits that is presumably associated with latitudinal variation in climatic conditions.

Factors influencing offspring traits in the oviparous multi-clutched lizard, Calotes versicolor (Agamidae).

The determinants of offspring size and number in the tropical oviparous multi-clutched lizard, Calotes versicolor, were examined using both univariate and multivariate (path) analyses. In C. versicolor maternal snout-vent length (SVL) and body condition influence clutch mass and clutch size but have no significant influence on offspring size. The positive effect of maternal SVL and body condition on offspring number is counterbalanced by a negative effect of breeding time on egg mass. In fact, breeding time directly influences the offspring body mass and condition through variation in the egg mass. There is a trade-off between offspring mass and condition with offspring number, and breeding time influences both. Offspring hatched from the eggs of early (May-June) or mid (July-August) breeding periods invariably show lower mass and condition than those hatched from the eggs of late breeding season (September-October). Yet, there is no variation in offspring SVL among early, mid and late clutches. Thus, in C. versicolor offspring SVL is optimized while body mass and condition are not optimized.

Intrapopulation variation in life history traits of Boa constrictor occidentalis in Argentina

AbstractWe provide data on intrapopulation variation of life history traits of Boa constrictor occidentalis in the District of Pocho, Córdoba, Argentina. A total of 153 individuals were captured. The distribution of individuals among four size classes differed significantly among the five years of study. The proportion of mature individuals did not differ between sexes but it showed variation among years. Females were longer and heavier than males. The mean litter size of the species was 24 and there was a linear relationship between litter size and maternal snout-vent length. Most boas were captured during the dry season. There were no significant sex differences in the time of capture and air temperature in either the wet or the dry seasons. However, we found significant differences in the time of capture and air temperature between the seasons. The long-term monitoring of wild populations should be a priority for the development of conservation and management plans for this boid.

Egg-Laying Activities and Reproductive Traits in Females of Oplurus cuvieri cuvieri

Egg-Laying Activities and Reproductive Traits in Females of Oplurus cuvieri cuvieri

Allometry of Clutch and Neonate Sizes in Monitor Lizards (Varanidae:Varanus)

This paper analyzes data from the published literature with the addition of some new information to explore the relationship between varanid body size and reproductive biology. Incubation time for varanid eggs is positively correlated with egg mass, neonate snout–vent length (SVL), and maximum adult snout–vent length (SVLmax). Incubation period of heavier eggs is proportionally less than for smaller eggs at 30 C. SVLmax is positively correlated with egg mass, clutch size, clutch mass, neonate body mass, and neonate SVL. Neonates of larger species have longer SVL but are smaller as a proportion of SVLmax than for smaller species. Clutch sizes are larger and more variable for larger species; however, clutch sizes for larger species relative to SVLmax are smaller than for smaller species. The intraspecific influence of maternal SVL on clutch size is greater than the interspecific influence of SVLmax on clutch size. These results suggest there are greater fitness advantages for smaller species having relatively larger offspring than for larger species, which concurs with results for snakes and other genera of lizards, as well as optimal offspring size theory. Reproductive output also appears to be influenced by maternal abdominal volume. Analysis of phylogenetically corrected data generally concurs with patterns evident in the nonphylogenetically corrected data. Body size has a much greater influence on reproductive output of Varanus than phylogeny.

Reproductive Cycle of the Oviparious Lizard Japalura brevipes (Agamidae: Reptilia) in Taiwan, Republic of China

-Japalura brevipes is an oviparous lizard native to high elevations of Taiwan, Republic of China. A total of 105 lizards (72 males; 33 females) were collected from March, 1992 to September, 1993. Males exhibited testicular recrudescence in spring; maximum spermiogenesis occurred in March-April. Testis somatic indices declined to a minimum in June and July. Fat body somatic indices were smallest in spring. Females lay eggs in late spring and summer. The average clutch size is 5.4. There was no correlation between maternal SVL and clutch size. Female fat body somatic indices declined to a minimum during March and July. Rainfall and temperature are considered the most important environmental factors that regulate J. brevipes reproductive cycles. Data on reproductive cycles, coupled with life history information, help us understand the evolution of lizard life history strategies (Tinkle et al., 1970; Vitt, 1981). Until 1960, research on the 1Present Address: Department of Zoology, National Museum of Natural Science, 1, Kuan Chien RD., Taichung, Taiwan, ROC. ctive cycles, coupled with life atio , help us understand the evoi life history strategies (Tinkle et ; i , 81). ntil 1960, research on the ess: epart ent of Zo logy, Nar productive biology of lizards was conducted almost entirely in north temperate regions (Clerke and Alford, 1993). Recently, there have b en extensive studies of tropical and Australian lizards (James and Shine, 1985; Joss and Minard, 1985; James, 1991; James et al., 1992; Clerke and Alford, 1993); however, investigations of the reproductive biology of lizards from subtropical regions remain scarce (Lin and Cheng, 1986). 22 This content downloaded from 207.46.13.25 on Mon, 12 Sep 2016 04:32:57 UTC All use subject to http://about.jstor.org/terms REPRODUCTIVE CYCLE IN LIZARD The genus Japalura is widespread in southeast Asia, north Borneo, Taiwan, and Ryukyu island (Lin and Cheng, 1990). Reproductive cycles of two species of this genus are known (Japalura swinhonis mitsukurii, Lin and Cheng, 1986; male J. swinhonis formosensis, Cheng and Lin, 1977). The purpose of this study is to provide information on the reproductive cycle of Japalura brevipes in relation to environmental factors that may influence it. MATERIALS AND METHODS The study site was located at Chunyang, Nantou County, about 90 km east of Taichung in central Taiwan (23? 30' N, 121? 08' E; ca. 1100 m above sea level). The site consists of 43 ha of man-made reforestation. The major plant species are the Gymnosperms Pinus taiwanensis, Cryptomeria japonica, and Cunninghamia lanceolata, the Dicotyledons Rhus semialata, Aralia taiwaniana, Rhododendron lasiostylum, Cinnamomum camphora, and Machilus zuihoensis. The average annual rainfall for Chunyang is about 2500 mm, most of which falls from February to September. The maximum air temperature in summer (June-August) ranges from 24 to 26?C, with minimum temperatures ranging from 14?-18?C during winter (November to January). Lizards were caught by noosing at monthly intervals between January 1992 and September 1993. The stage of maturity of males was judged by the appearance of the testes and epididymides which have free sperm in tubules, and were small and without convolutions in immature specimens. Females were considered immature if they had only small follicles in the ovary (diameter 3 mm. The estimation of clutch size was based on the number of vitellogenic follicles and/or oviductal eggs. The presence of vitellogenic follicles and oviductal eggs in the same female was considered evidence of the production of at least two clutches. The male reproductive state was estimated according to the GSI (Gonad-Somatic-Index) and spermatogenetic activity. The right testis from each male was fixed in Bouin's solution, embedded in paraffin, sectioned at 6 um, and stained with hematoxylin and eosin. Spermatogenetic activity was qualitatively assessed according to the classification system of Licht (1967). The stages are: (1) seminiferous tubules involuted with spermatogonia only; (2) primary spermatocytes appearing; (3) secondary spermatocytes and early spermatids abundant; (4) transforming spermatids with few spermatozoa; (5) spermatids and spermatozoa abundant; (6) spermatozoa abundant, (maximal level of spermiogenesis); and (7) spermatozoa abundant, (spermatids and spermatocytes greatly reduced). The presence of spermatozoa in the epididymis was noted. The relationship between clutch size and female body size was examined using a Pearson's correlation analysis. Monthly changes in fat body, liver, and testis mass were assessed using analysis of covariance (ANCOVA) with snout vent length (SVL) as the covariate.