Average Snout-vent Length Research Articles

Doğu Akdeniz, Türkiye'deki Su Kurbağalarının (Pelophylax ridibundus-complex) Üreme Ekolojisi ve Larval Gelişimi

Reproductive biology of Marsh frogs (Pelophylax ridibundus s.l.) was investigated in the Eastern Mediterranean Region of Türkiye in terms of reproductive phenology, fecundity, clutch size, reproductive effort, and mate choice. Frogs are active for approximately ten months throughout the year and hibernate between November and January. Breeding occurs from mid-January until early June and metamorphosis took 45-65 days, with juveniles observed from the end of March. The tadpole reaches its largest size at stage 38, with a mean total length of 60.61 mm and juveniles have an average snout-vent length of 20 mm at the end of metamorphosis. Secondary sexual characters can be observed on individuals reaching 45 mm snout-vent length and we could not detect any amplexed pairs below this length. The clutch size of spawned egg masses ranged between 144 – 645 and the mean egg size was calculated as 1.73 mm. The mean fecundity was 3853 (ranging between 940 and 6000) eggs and the reproductive effort was 0.094 in females. Females were approximately 16% larger than males and the snout–vent length of males and females of amplexed pairs is significantly different but not correlated. These findings signify random mating instead of size-assortative mating. However, the preference of 6.8% larger females than single ones to mate indicates a size-dependent mating for Western Mediterranean population.

Population structure and dynamics, breeding activity and phenology of the blue‐sided treefrog (Agalychnis annae)

Abstract Agalychnis annae is a species endemic to Costa Rica and Panama with populations shrinking or disappearing from several locations. We studied the reproduction of a relict population of A. annae in a 1,300 m2 natural pond in Costa Rica during 2007–2008. We marked adults with a visible implant alphanumeric tag injected in the thigh. We measured reproductive effort considering calling males per night and per hour, number of pairs in amplexus, and number of egg masses. We summed 366 individual observations: 57% juveniles, 39% adult males, and 4% adult females. Average snout–vent length was 29 mm (juveniles), 63 mm (males), and 78 mm (females). Sex ratio (males:females) was 4.85:1, while operational sex ratio varied between one and six males per female when both sexes were present at the pond. Maximum estimated census population size varied between 27 and 59 individuals, with a Ne = 43.11. Calling activity occurred mostly from 1800–2000 h, and we counted 65 egg masses. Number of adults and calling males were positively correlated with accumulated rainfall and average temperature. Number of egg masses was positively correlated with the number of adults, accumulated rainfall, and average temperature. The causes of the long‐term population decline must be identified to conserve A. annae and similar species, as well as establishing long‐term monitoring programs. Required conservation actions include translocation individuals from risky areas, creation of artificial ponds to increase ecological connectivity, elimination of introduced species, particularly in small habitat remnants, and establishment of ex situ conservation programs.Abstract in Spanish is available with online material.

The Study on the Relationships Between the Age Structure and Body Size of the Bridled Skink, Heremites vittatus, (Oliver, 1804) from Different Altitudes in Turkey

Age structure and body size of Heremites vittatus from three different altitudes (group I: 0-499 m, group II: 500-999 m, and group III: above 1000 m) were investigated using skeletochronology. The mean snout-vent length (SVL) of females in all groups was larger than males. The average SVL was 74.8 mm in females and 66.8 mm in males. Age ranged from three to seven years in females and two to seven years in males. No significant differences were found in mean age between sexes (Mann-Whitney U-test, p=0.324). Among three groups, there was no significant difference between the populations as regards both age and SVL. However, SVL only in groups I and II were statistically significant between sexes. Moreover, there was no significant correlation between age and SVL. The Von Bertalanffy’s model indicated that females had a larger asymptotic body size than males and that there was a significant difference between the sexes in terms of growth rate.

Body size, age and growth in males populations of Boana pulchella (Anura, Hylidae).

Age determination in amphibians is crucial to the investigation of life-history traits. In this context, we studied, for the first time, the life-history traits of Boana pulchella from a sample (63 adult males) of three populations (Las Acequias, Río Cuarto, Alejandro Roca) in central Argentina using the skeletochronological method. All adults of B. pulchella studied showed recognizable bone structures that allowed age determination. The average snout-vent length of sexually mature males was 43.39 mm. The maximum observed longevity was 5 years (5 Las Acequias, 4 Río Cuarto, 3 Alejandro Roca) and minimum age at sexual maturity was 2 years (same in the three populations), with mean of 2.96 years. Body size and age were positively correlated (except in Alejandro Roca populations). The growth patterns, estimated by the von Bertalanffy growth equation, do not show differences between populations, and the growth rate decrease after the attainment of sexual maturity. In conclusion, the determination of the individual age of the different populations of B. pulchella allowed us for the first time to establish the characteristics of the life history of the species, important for future comparisons whit others populations and future conservation biology studies.

Genomic pedigree reconstruction identifies predictors of mating and reproductive success in an invasive vertebrate.

The persistence of an invasive species is influenced by its reproductive ecology, and a successful control program must operate on this premise. However, the reproductive ecology of invasive species may be enigmatic due to factors that also limit their management, such as cryptic coloration and behavior. We explored the mating and reproductive ecology of the invasive Brown Treesnake (BTS: Boiga irregularis) by reconstructing a multigenerational genomic pedigree based on 654 single nucleotide polymorphisms for a geographically closed population established in 2004 on Guam (N = 426). The pedigree allowed annual estimates of individual mating and reproductive success to be inferred for snakes in the study population over a 14‐year period. We then employed generalized linear mixed models to gauge how well phenotypic and genomic data could predict sex‐specific annual mating and reproductive success. Average snout–vent length (SVL), average body condition index (BCI), and trappability were significantly related to annual mating success for males, with average SVL also related to annual mating success for females. Male and female annual reproductive success was positively affected by SVL, BCI, and trappability. Surprisingly, the degree to which individuals were inbred had no effect on annual mating or reproductive success. When juxtaposed with current control methods, these results indicate that baited traps, a common interdiction tool, may target fecund BTS in some regards but not others. Our study emphasizes the importance of reproductive ecology as a focus for improving BTS control and promotes genomic pedigree reconstruction for such an endeavor in this invasive species and others.

DỊ HÌNH KÍCH THƯỚC GIỚI TÍNH VÀ SINH THÁI DINH DƯỠNG CỦA LOÀI CHÀNG XANH (Hylarana erythraea) Ở VÙNG PHÚ LỘC, TỈNH THỪA THIÊN HUẾ

The Common Green Frog, Hylarana erythraea (Schlegel, 1837), is an important species in both terrestrial and aquatic ecosystems. However, information on sexual size dimorphism (SSD) and the feeding ecology of this species in Vietnam is currently lacking. We used the stomach-flushing method to obtain food items from 223 stomach specimens. The results showed that the average snout-vent length was significantly larger in adult females than in adult males, with an SSD index of 0.57. The most important prey categories of H. erythraea were Coleoptera, unidentified insect larvae, Odonata, Orthoptera, and Araneae (occurrence frequency 65.45 %, representing 65.89 % of the number of items, and 81.04 % of the total volume). The mouth width and snout-vent length had significant effects on the prey size and on the volume of food items. However, air temperature and relative humidity did not have significant effects on the prey volume or size of individual food items. These results supported the hypothesis that “the mouth size is the limiting factor on the food size” in anuran species.

Life History of a Unique Asian Plethodontid Salamander, Karsenia koreana.

Using preserved specimens, we studied the basic life history of the topotypic population of the unique Asian plethodontid salamander, Karsenia koreana. Of 51 individuals examined, 11 males and 13 females were judged as mature from the development of gonads. The ovarian eggs were large (diameter 3.7-4.8 mm) and yellow to orange in color, and the clutch size was about 8-10. These values approximate those of actually spawned eggs recently reported. Skeletochronological analyses revealed the average age of males (5.3 years) to be lower than females (7.3 years). The age at maturity and maximum observed longevity were four and nine years in males and five and 10 years in females, respectively. In the growth curves estimated by a von Bertalanffy growth model, the growth coefficient and asymptotic SVL did not differ between the sexes, although males (40.6 mm) were smaller than females (45.3 mm) in the average snout-vent length. The time and place of courtship behavior, oval development, hatching, and especially, whether the species shows aquatic larval stage or direct development, are important topics to be resolved in future.

Filling in the Gaps: Natural History and Conservation of Bolitoglossine Salamanders in Central Panama

The goal of this study was to document the natural history of salamanders in central Panama and assess their response to drought conditions, which are predicted to become more common as a result of climate change. We conducted 123 transect surveys at night along a concrete trail in a natural area protected by the Panamanian national environmental authority Autoridad Nacional Ambiente (ANAM.) We marked 122 individuals, including two genera and three species, Bolitoglossa biseriata, Oedipina complex, and Oedipina parvipes, from 1 June to 30 July 2013, 10 December 2013 to 6 January 2014, and 1 June to 30 July 2014. All three field seasons took place during a long-term Central American drought. The mean mass of B. biseriata, the most common species of salamander encountered, was 0.8±0.4 g with an average snout–vent length (SVL) of 31.45±5.30 mm. A principal component analysis indicated that B. biseriata utilized all of the available ground-level habitats where surveys were conducted. Bolitoglossa biseriata mo...

Age structure and body size of the Strauch’s racerunner, Eremias strauchi strauchi Kessler, 1878

We studied, for the first time, the age structure of Eremias strauchi strauchi (Kessler, 1878) from a sample (18 adults) of a population living in the vicinity of Iğdır (eastern Turkey) using the skeletochronological method. The maximum observed longevity was 7 years for males and 5 years for females. The age of males ranged from 4 to 7 years (mean 4.91, n = 12), while that of females ranged from 4 to 5 years (mean 4.66, n = 6). The average snout–vent length (SVL) was 61.10 mm in males and 60.82 mm in females. The differences in mean age and SVL between sexes were not statistically significant. Intersexual differences in body size were male-biased, but this state was not statistically significant. Age and SVL were positively correlated in both sexes.

Evidence of phoresy by leeches (Hirudinoidea) on Rhinella abei (Anura: Bufonidae) in the Atlantic Rainforest in the state of Santa Catarina, southern Brazil

May. Abstract. In the Atlantic Rainforest of the Parque Estadual da Serra do Tabuleiro, state of Santa Catarina, southern Brazil, we found Rhinella abei (Bufonidae) infested by leeches (Hirudinoidea). We captured 27 toads on the margin of a lagoon both inside and outside water in a survey carried out during one night, and 13 of which had a total of 30 leeches (mean intensity of infestation = 2.3 ± 1.3). We did not observe wounds, scars and/or hemorrhages caused by the leeches on the toads exam- ined, no hemorrhaging after the removal of the leeches, and the leeches removed from the toads were empty of blood. This evidence led us to theorize that the leeches were not parasitizing the toads but had a phoretic relationship. The leeches were found on both dorsal and ventral surfaces (13 on each) of the toads and were predominantly on the toads' axils followed by back and thighs. The average snout-vent length of the toads was 69.2 ± 5.3 mm and their average body mass was 27.1 ± 6.9 g. The number of leeches found on a toad was not related to its snout-vent length or body mass. We are unaware of any previous records of leeches using anurans as dispersal agents, as suggested in the present study.

Morphological Variation ofSordellina punctata(Peters, 1880) with Notes on the Phylogenetic Position of the Genus within the Family Dipsadidae (Serpentes)

Sordellina punctata(Peters, 1880) is a poorly known species from Brazil that, until recently, had an uncertain phylogenetic position. Sixty-one specimens ofSordellina punctatawere examined, representing different localities encompassing the known geographic distribution of this taxon. Eight skulls and five hemipenes were prepared and described in detail and data on scale variation and color pattern as well as morphometric data were analyzed. The skull bones described, as well as the hemipenis ofS. punctata, were compared to available data in the literature referred to members of the tribe Echinanterini and related taxa.Sordellina punctatapresents an average snout-vent length of 31.5 cm for males and 40.2 for females and has an average of 149 ventral scales in males and 157 in females. The data presented here reinforce the necessity of a greater amount of osteological descriptive studies, especially of members of the tribe Echinanterini, in order to evaluate the recently proposed hypothesis of relationship ofS. punctataand these taxa.

Morphology of Vipera palaestinae : Intraspecific Variability and Sexual Dimorphism

I present new data on intraspecific variations in external morphology and sexual dimorphism in different characteristics of Vipers, Vipera palaestinae in Israel. Corporal proportions and scalation pattern of museum specimens of this snake, the most common viperid species in Israel, were recorded and analyzed. Strong sexual dimorphism was found in tail measurements (its relative length, and number of subcaudal scales), head proportions and in the number of ventral scales. The sexual differences were evident in the head scalation – females have significantly more supralabial and sublabial scales; males, in turn exceed females in circumorbital scale counts. There is no sexual size dimorphism (SSD) in average body weight, snout-vent and total length. The sexes display a similar allometry between SVL/head and SVL/tail length; between tail length and the number of subcaudal scales (weak, but significant relationship). There is no correlation between SVL and the number of ventral or dorsal scales. The morphological plasticity caused by reproduction requirements is well registered and was evident in relating to tail measurements and body scalation, although the possible causes and selective forces of the pholidosis intersexual distinctions can be cleared up through future ecological studies.

Growth, size and age at maturity of the agile frog ( Rana dalmatina) in an Iberian Peninsula population

The mean age of a population of agile frogs ( Rana dalmatina) from the Iberian Peninsula was estimated using mark and recapture and skeletochronology. Life-history parameters, including growth rate, body length, age and size at maturity, sexual dimorphism and longevity, were studied. The regression between age and snout–vent length (SVL) was highly significant in both sexes. Males reached sexual maturity at two years of age, although sometimes they can reach it at only one year of age. The average SVL at maturity was 51.75 mm (standard error (SE) = 0.71; n = 45). Females reached sexual maturity at two years of age with an average SVL of 62.14 mm (SE = 2.20; n = 14). A subset of the female population reached sexual maturity at three years of age. Growth was rapid until sexual maturity was reached. There was an overlap of SVL between different age classes. Growth was continuous, fulfilling the conditions of Von Bertalanffy's model. The growth coefficient ( K) was 0.840 in males and 0.625 in females. The maximum SVL was greater in females (73.00 mm) than in males (59.50 mm). Sexual dimorphism was significantly biased towards females in all age classes. The maximum longevity observed was 6 years in females and 8 years in males. Management strategies for agile frogs should take into account factors such as these life-history characteristics.

A multiyear comparison of the male reproductive biology of the brown treesnake (Boiga irregularis) from Guam and the native range

Previous studies have suggested that reproduction in the brown treesnake (Boiga irregularis) is reduced on Guam because of elevated stress hormones caused by limited food availability. This study examined the reproductive anatomy of male brown treesnakes on Guam over a 15-year period (1985–99) to determine whether the size at maturity and development of the testis and sexual segment of the kidney varied between years and to compare these data to those for snakes collected from the native range. On Guam, the average snout–vent length and body mass of B. irregularis has decreased from its high in 1985 and remained stable from 1989 to 1999. The snout–vent length at maturity was similar between years. Mean diameters of the seminiferous tubule and the sexual segment of the kidney were not significantly different between years. However, the number of sexual segment tubules hypertrophied per snake varied greatly. Snakes from the native range matured at smaller snout–vent lengths and had significantly more hypertrophied sexual segment tubules per kidney than populations on Guam. These data suggest that elevated plasma levels of corticosterone, potentially due to an increase in male–male interactions as a result the explosive population growth experienced on Guam, may be negatively influencing male reproduction.

A New Species of Minute Noblella (Anura: Strabomantidae) from Southern Peru: The Smallest Frog of the Andes

We describe a new species of Noblella from the upper Cosñipata Valley in southern Peru (Cusco Region). Specimens were found in the leaf litter of a cloud forest between 3025 and 3190 m elevation. The most distinctive character of the new species is its diminutive size (maximum SVL female 12.4 mm, male 11.1 mm). With an average snout–vent length of 11.4 mm (n = 7) in adult specimens, the new species is the smallest Andean frog, and one of the smallest anurans in the world. The new frog is rare (between 30 and 75 frogs/ ha) and found only in montane scrub and forest habitats near the ecotone with the high-Andean puna grasslands. Although the amphibian fungal infection (Batrachochytrium dendrobatidis) has been recorded in southern Peru, no infections were detected in the new species.

Quantitative analysis of production traits in saltwater crocodiles (Crocodylus porosus): I. reproduction traits

Repeatability and phenotypic correlations were estimated for saltwater crocodile reproductive traits. No pedigree information was available to estimate heritability or genetic correlations, because the majority of breeder animals on farms were wild-caught. Moreover, as the age of the female breeders could not be accounted for, egg-size measurements were used as proxies. The reproductive traits investigated were clutch size (total number of eggs laid), number of viable eggs, number of eggs that produced a live, healthy hatchling, hatchability, average snout-vent length of the hatchlings and time of nesting. A second data set was also created comprising binary data of whether or not the female nested. Repeatability estimates ranged from 0.24 to 0.68 for the measurable traits, with phenotypic correlations ranging from -0.15 to 0.86. Repeatability for whether a female nested or not was 0.58 on the underlying scale. Correlations could not be estimated between the measurement and binary traits because of confounding. These estimates are the first published for crocodilian reproduction traits.

NATURAL HISTORY OF THE MASSASAUGA, SISTRURUS CATENATUS EDWARDSII, IN SOUTHEASTERN COLORADO

A BSTRACT Studies of natural history are important for determining baseline information, particularly for species that might be threatened or endangered. We collected 254 (141M:94F:19UNK) massasauga, Sistrurus catenatus edwardsii, from May 1995 through October 1996. The average snoutvent length (SVL 6 SD) for adult males (355 6 45 mm) was not significantly different than the SVL of adult females (364 6 24 mm). Habitat descriptions indicate that the massasauga in Colorado is a semi-arid grassland species that utilizes areas of relatively open shortgrass prairie. Massasaugas were active between 14 and 308C, with an average ambient temperature during activity of 22.1 6 2.58C. The time of observed activity shifted through the season, with primarily diurnal activity during the cooler months (April and late September to October) and primarily early evening activity during the hotter months (May through August). Massasaugas in Colorado gave birth to litters of 5 to 7 young between late August and late September, and reproduction appeared to be biennial. Populations of S. c. edwardsii in Colorado are scattered but population size appeared to be relatively large based on number of captures and low recapture rates, particularly in Lincoln County. However, due to habitat loss and fragmentation resulting from agricultural expansion, these populations might become increasingly threatened in the future.

NATURAL HISTORY OF THE TEXAS HORNED LIZARD, PHRYNOSOMA CORNUTUM (PHRYNOSOMATIDAE), IN SOUTHEASTERN COLORADO

Abstract Colorado Division of Wildlife currently considers the Texas horned lizard a species of special concern. From May 1995 to October 1997, Texas horned lizards were captured or collected during the active season from 6 counties in Colorado to document abundance and distribution of the species. We captured or collected 290 Texas horned lizards (170 alive and 120 dead on road). In Colorado, average snoutvent length (SVL) for adult males was not significantly different from females; the largest male and female lizards measured 84.9 mm SVL and 90.4 mm SVL, respectively. The sex ratio of adult males to adult females is 1M:1.4F. Results of distribution and habitat analysis indicated that the Texas horned lizard in Colorado is locally common in arid shortgrass and sand-sage prairie lacking ground litter. Activity of the Texas horned lizard in Colorado is diurnal in spring and fall and bimodal (almost crepuscular) in the summer. Texas horned lizards in Colorado apparently breed in May and June, and hatchling...

Reproductive characteristics of a lowland population of an alpine lizard: Lacerta monticola (Squamata, Lacertidae) in north-west Spain

Abstract We studied the reproductive ecology of a population of the lacertid lizard Lacerta monticola at a lowland location in A Coruña (NW Spain) from 1997 to 2002. The timing of the reproductive cycle was examined based on mark-recapture records of individual lizards in the field. The characteristics of the eggs and hatchlings were obtained from clutches laid in the laboratory by pregnant females that were temporarily removed from the study area. Our results indicate that mating took place between late March and July. The smallest female with signs of sexual maturity had a snout-vent length (SVL) of 52.4 mm and the smallest male was 50.7 mm. Sexual maturity was attained at the age of 2 years by 41% of the individuals, while the remaining 59% of the lizards matured at the age of 3 years. The laying period occurred between June and the beginning of August considering all years. About 61% of the reproductive females produced a single clutch annually, while 39% of the females produced two clutches per year. Females that produced two clutches were generally larger (average SVL = 70.9 mm) than those that laid a single annual clutch (average SVL = 62.6 mm). The mean clutch size was 6.4 eggs (range 4-9). Both clutch size and clutch mass increased significantly with female SVL. The mean egg mass in a clutch decreased significantly with clutch size. Hatching occurred between August and September. Hatching success in the laboratory was 71.7%. The mean SVL was higher in female hatchlings than in males.

Population Dynamics of Eleutherodactylus coqui in Cordillera Forest Reserves of Puerto Rico

Various aspects of population structure and dynamics of Eleutherodactylus coqui in two forest reserves (Maricao and Guilarte) of the central mountain range of Puerto Rico were determined between July 1997 and June 1998. Adult density ranged from 8–25 animals/100 m2 for the wet season and 3–19 animals/100 m2 for the dry season. Abundance of froglets and juveniles was also greater in the wet season compared to the dry season. By contrast, egg mass counts were greater in the dry season compared to the wet season. Adult body size increased from wet to dry season as population density declined and was found to differ significantly between forests. Adult E. coqui trapped at similar elevations were larger in Guilarte compared to those in Maricao. Average body size for Maricao and Guilarte populations were smaller than those reported for populations in eastern Puerto Rico. Comparing average snout–vent length among frogs from the Luquillo Mountains, Guilarte Forest, and Maricao Forest, a gradient of decreasing body size was observed from east to west across the island.