Yolked Follicles Research Articles

Addition of the Sea Snake, Hydrophis stokesii (Reptilia: Squamata: Elapidae), to the Herpetofauna of Japan

Hydrophis stokesii was collected in the coastal water of Okinawajima Island on 30 March 2021. This is the first record of the species from Japanese waters, extending its known range of occurrence toward east-northeast by more than 900 km. The snake was an adult female, 1,545 mm in snout-vent length, 203 mm in tail length, and 3,360 g in body mass. It had 11 well-developed yolked follicles in ovaries and a half-digested spiny puffer fish (Diodon sp.) in its stomach. This individual may possibly represent a stable population of H. stokesii in the Okinawan waters.

Female reproductive cycle and batch fecundity in the central-southern Adriatic population of Engraulis encrasicolus (Osteichthyes: Engraulidae)

The European anchovy, Engraulis encrasicolus, is a multiple-spawning small pelagic fish with a comparatively long reproductive season. From April to October 2009, ovary samples were collected from individuals of the southwestern Adriatic Sea in order to examine ovarian histological changes and assess batch fecundity monthly variations throughout the whole reproductive season. To assess monthly variations of the relative batch fecundity, the correlation between batch fecundity (F) – i.e. the number of oocytes released at each spawning act – and ovary-free body mass (W*) was tested by four regression models; the power equation () was found to be the most suitable to describe correlations. The reproductive season of the anchovy of the central-southern Adriatic population lasts from May to September; in this period, all the oocyte development stages were observed, including hydrated oocytes and postovulatory follicles. In April, most fish had only unyolked oocytes; in October, an extensive atresia of yolked follicles was observed. The slope of all the on monthly regressions did not differ significantly from 1, which shows that relative batch fecundity is constant all over the anchovy size range, throughout the spawning season. In the central-southern Adriatic anchovy population, batch fecundity increased from May to July and then gradually decreased until September. Differences in batch fecundity of the anchovy from different areas of the eastern Atlantic and Mediterranean could possibly be due to both environmental parameters and genetic differences among the different populations.

Reproductive Ecology ofQuasipaa verrucospinosa(Bourret, 1937): Living in the Tropical Rain Forests of Central Vietnam

Quasipaa verrucospinosa, the Granular Spiny Frog, is a discoglossid frog endemic to Vietnam and known only from its original description. We report the discovery of three populations of this species and describe the reproductive, fat body, and liver mass cycles for males and females. Results showed that males reached sexual maturity at 98.36 mm snout–vent length (SVL) and an age of nine months. Females reached sexual maturity at 109.45 mm SVL and an age of 11 months. Testes of males began to increase in volume in late June, and maximal testicular activity occurred from September to December. Testis size began to decrease in January and was smallest in April. Histological analyses revealed that sperm were not present throughout the year, indicating discontinuous reproductive activity for adult males. Reproductive females were observed only during the main rainy season months, indicating that females reproduce seasonally. The gonads of females began to increase in volume in July and maximal egg production occurred during the main rainy season (September to December). Females started to lay their eggs in July, and there were significant differences among mean clutch size and numbers of oviductal eggs or yolked follicles, vitellogenic follicles, and nonvitellogenic follicles. Clutch size was correlated significantly with female SVL and varied between seasons and months. The results of multiple regression analyses indicated that precipitation, but not temperature, was associated positively with testicular and ovarian volume.

Assessment of Mercury and Selenium Concentrations in Tissues of Stranded Leatherback Sea Turtles (Dermochelys coriacea)

The impact of mercury (Hg) and selenium (Se) compounds on wildlife health is an issue of concern, especially because anthropogenic practices (e.g., fossil fuel combustion, metal processing) release these trace elements and their compounds into the environment where they become incorporated into food chains. Little is known about the concentrations of these elements in tissues (other than in blood) of most wild reptiles, especially for pelagic species. The purpose of this study was to document Hg and Se concentrations in leatherback sea turtles, Dermochelys coriacea. To assess Hg and Se concentrations in leatherbacks, multiple tissue samples (whole blood, enteric contents from the small intestine, feces, yolked follicles, liver, and salt gland) were collected from dead, stranded male and female leatherbacks that were assigned to three life stage classes (juvenile, subadult, adult) identified at gross necropsy. The tissues were tested for Hg and Se concentrations. The liver exhibited the highest concentrations of both Hg and Se compared with other tissues. Adults had the highest concentrations of Hg in their livers compared with juveniles and subadults; however, Se concentrations did not differ between subadults and adults. Leatherbacks with a larger curved carapace length had greater liver Hg and Se concentrations. The Se:Hg ratio in the liver was highest in juveniles, followed by subadults, and then adults. Because these animals are long-lived, Hg or Se accumulation may become a physiological challenge, especially because of ongoing anthropogenic input of these elements and their compounds into the environment. Further population monitoring of toxicants in marine turtles is warranted to determine whether tissue concentrations of these elements continue to increase long term or vary with age, life stage, sex, or reproductive status.

Reproduction of an Introduced Population of Eleutherodactylus johnstonei at Bucaramanga, Colombia

Comparative ecological data on introduced populations can contribute to understanding why Eleutherodactylus johnstonei is a good invader. We studied the reproductive features of an introduced population of this species and compared them with similar data on other introduced and native populations. Females were larger than males; sexually mature males ranged between 17–29 mm snout vent length and females between 23–32 mm. Reproductive males and females were captured throughout the year and there were no monthly significant differences in their occurrence. Clutches and neonates occurred year-round. The adjusted testicular volume did not vary significantly among months and histological analyses of the testes and ducts revealed the presence of sperm through the year, indicating continuous reproductive activity for males. The ovarian volume did not vary significantly among months and the presence of yolked follicles were observed throughout the year, indicating that females also reproduce continuously. There was a positive relationship between female body size and the number of yolked follicles. Two different relationships associated with reproduction could explain sexual differences in body size; the larger body size in females allows greater clutch sizes, and the energy cost of calling activity and paternal care of the clutch limits male growth. The colonizing success of E. johnstonei appears to be related to its reproductive features, such as flexibility in reproductive activity, direct development, and parental care of the clutch, allowing it to easily occupy disturbed areas that it encounters.

Reproductive and feeding ecology of the amphisbaenian Anops kingii in east-central Argentina

AbstractThe reproductive and feeding ecology of Anops kingii was studied at the pampas mountain range of Argentina. Reproduction occurred from late winter (July) to early summer (December). Mean clutch size, based on the number of oviductal eggs, ranged from 2 to 4 eggs (x¯= 3), whereas mean clutch size based on the number of yolked follicles was 2.2 eggs. Adult females were significantly larger than males and all male individuals had conspicuous precloacal pores, whereas all females lacked them. Diet was not diverse and consisted mainly of coleopteran larvae. Foraging activity decreased during the coldest months of the year. Individuals were found under large rocks predominantly during winter and spring. This seasonal pattern of activity near the surface would seem to be related more to thermoregulatory than to trophic requirements.

Characterization of Rattlesnake Harvest in Florida

Characterization of Rattlesnake Harvest in Florida

Reproduction in the toad Colostethus trinitatus (Anura: Dendrobatidae) in a northern Venezuela seasonal environment

ABSTRACTVarious aspects of the reproductive biology of a montane population of Colostethus trinitatus were quantified during the transition from a prolonged dry season to a wet season with abnormally low rainfall. One-third to three-quarters of the females collected in the dry period (March to June) had mature ovarian follicles. The proportion of ovigerous females did not increase in July or August when the number of rainy days was greater. However, breed-ing and egg laying were only observed in the latter season. The principal environmental change that stimulated oviposition was frequent daily rain which increased humidity in the terrestrial nest sites.Pair formation, nests, and males carrying larvae are reliable criteria that indicate the breeding period of Colostethus trinitatus. The average number of mature ovules (>2 mm) was greater in the wet season (=13.1) than during the dry months (= 11.3). Female standard length and the number of yolked follicles was positively correlated. Five nests contained an average of 13.6 eggs, and males carried only slightly fewer larvae (= 11.5). One female and one individual of unknown sex were found with eggs at two different nests. Five nests were unattended.

Effects of Pentastome Infection on Reproduction in a Southern Texas Population of the Mediterranean Gecko, Hemidactylus turcicus

Forty-three percent of adult Mediterranean geckos, Hemidactylus turcicus, from southern Texas were infected with a pulmonary pentastome, Raillietiella frenatus. Pentastome occurrence and biomass did not affect carcass, liver or testis mass of males or carcass mass of females through the year. However, liver mass in females during the nonreproductive period and fatbody mass in both sexes during the reproductive period was significantly lower in individuals with the highest biomass of pentastomes. Infected females had a higher frequency of medium sized yolked follicles than uninfected females, but the latter had a significantly higher frequency of oviductal eggs than infected female geckos. We estimated that oviductal egg production in this gecko population was reduced by 21% due to the pentastome infection. These data indicated that this macroparasitic infection should be considered as a possible factor in the population regulation of H. turcicus in southern Texas.

Annual Reproductive Patterns in Three Species of Marine Snakes from the Central Phillippines

Monthly samples of three tropical snakes, Acrochordus granulatus, Cerberus rhynchops and Laticauda colubrina from a limited collecting area where they are syntopic in the central Phillippines reveal pronounced diversity in reproductive seasonality. Both sexes of A. granulatus are highly seasonal and synchronized in their reproductive activity. Testis size, spermatogenic activity and plasma androgen levels declined precipitously in the non-breeding season to the same extent as observed in typical temperate species of snakes. Spermatogenesis and androgen secretion occur concomittantly and are prenuptial, coinciding with the appearance of enlarging yolked follicles in females. Gestation time (5-8 months) in this species may repesent one of the longest for a reptile, and females probably do not breed annually. C. rhynchops is also seasonal but to a lesser extent than Acrochordus. In males, testis weight, spermatogenesis and androgen secretion show a significant increase at certain times of year, but testis regression is only partial; there is some spermatogenic activity and epididymal sperm storage in all months. Gestation periods in this ovoviviparous species are probably much shorter (perhaps 3 months) than in Acrochordus, ovulation occurs over a broader season and females probably reproduce annually. In contrast, extensive evidence for male L. colubrina and limited observations on females indicate that this oviparous species is probably completely aseasonal in its reproductive biology. A review of reproductive data on other tropical marine snakes suggests that seasonality is probably the rule with the exception of L. colubrina (and some other species of Laticauda), the only oviparous species examined. Information on climatic conditions in the study area sugests that declining photoperiod and/or temperature may be responsible for testicular regression in Cerberus and Acrochordus. Data for plasma sex steroids (testosterone, estradiol and progesterone) suggest greater variability in ovarian function than previously reported for snakes.

Reproduction in a Nebraska Sandhills Population of the Northern Prairie Lizard Sceloporus undulatus garmani

Reproduction in a Nebraska Sandhills Population of the Northern Prairie Lizard Sceloporus undulatus garmani

Population Structure and Reproductive Characteristics in Cnemidophorus parvisocius (Lacertilia: Teiidae)

Cnemidophorus parvisocius Zweifel is one of the smallest and southernmost species of the sexlineatus species group in Mexico. It occupies the more xeric habitats in the remote Tomellin Canyon in southeastern Puebla and N-central Oaxaca between 518-1692 m elevation. Analysis of snout-vent length data for 457 adults of C. parvisocius revealed the presence of a small northern variant (females, X = 57.4 mm; males, X = 61.3 mm) and a larger southern variant (females, X = 60.3 mm; males, X = 65.5 mm). Males and females are reproductively mature by June following the year of their hatching. Analysis of three geographic samples revealed no variation in clutch size. Clutch size, based upon yolked follicles and oviducal eggs, varied from 1-4 (X = 1.77, 151/85). Cnemidophorus parvisocius has the smallest clutch size reported for a species of the sexlineatus group.

Comparative Reproductive Biology of Two Sympatric Tropical Lizards Chamaeleo jacksonii BOULENGER and Chamaeleo hoehnelii STEINDACHNER (Sauria: Chamaeleonidae)

AbstractThe reproductive biology of two sympatric tropical lizards Chamaeleo jacksonii and C. hoehnelii was investigated from April 1972 to June 1973 in Karatina, Kenya. The smallest gravid female was 80 mm SVL in C. jacksonii, and 67 mm SVL in C. hoehnelii. The smallest male showing enlarged testis, epididymis and as deferens was 90 mm SVL in C. jacksonii and 70 mm SVL in C. hoehnelii. The age at sexual maturity was estimated to be approximately 91/2 months for female C. hoehnelii and 101/2 months for male C. hoehnelii, 131/2 months for female C. jacksonii and 16 months for male C. jacksonii. Both species are viviparous. Monthly means of testis weight/SVL in C. jacksonii revealed a seasonal cycle with a minimum in August and a maximum in February. The monthly means of kidney weight/SVL showed a cyclic pattern slightly different from the testicular cycle, in that kidney size peaked during period in which actual matings were observed. Parturition began in mid-January and persisted into March in C. jacksonii. Post-reproductive quiescence extended from January to March. Vitellogenesis extended from mid-March through August, and the peak of ovulation occurred in August. Gestation began early in July and extended into February. Although female C. jacksonii require more than a year to mature, some apparently gave birth during their first post partum breeding season at an age of 14-15 months. The average litter size was 21.7 in C. jacksonii. Litter size increased strongly with SVL and age, and slightly with reproductive category. Reproductive effort was 46.7%, 51.9%, 46.4%, 42.8%, and 39.7%, respectively for the first, second, third, fourth and fifth year old individuals. Both male and female C. hoehnelii reproduced continuously throughout the year as shown by the testicular and kidney cycles for males, and by the continuous presence of yolked follicles, oviducal ova and fertilized ova every month for females. The average litter size was 13.7 in C. hoehnelii. Litter size correlated positively with SVL. Reproductive effort was 53.6%, 44.6%, 40.4%, and 40.5%, respectively for the first, second, third and fourth year old individuals. Although C. jacksonii and C. hoehnelii are two closely related species, and occur sympatrically, their reproductive patterns are widely divergent, and are found to be on the opposite sides of Tinkle's dichotomy. It is proposed that C. jacksonii and C. hoehnelii evolved in allopatry. The presently known distribution and current theory of lizard reproductive strategy support this proposal.

Reproduction and Growth of the Mud Turtle, Kinosteron subrubrum (Reptilia, Testudines, Kinosternidae), in Arkansas

Female Arkansas mud turtle (Kinosteron subrubrum) mature between their sixth and eighth winters at a plastron length of 75 to 80 mm. Vitellogenesis apparently begins in early fall and continues until the following nesting season. Ovulation and oviposition occur at least from early May through June and probably from early April to Mid-July. During this period yolked follicles continue to mature, replacing those ovulated. Egg size is not correlated with female plastron length or clutch size. Incubation period averages 106 days. Clutch size ranges from one to six, the mode being three, and is positively correlated with female plastron length. At least three clutches are laid each year. * * *

Reproductive Strategies in Sympatric Whiptail Lizards (Cnemidophorus): Two Parthenogenetic and Three Bisexual Species

Reproductive characteristics in five sympatric Cnemidophorus species were similar. All were multi-brooded with small clutches and low clutch weight/body weight ratios, an estimate of reproductive effort (RE). Interspecific differences in mean clutch sizes and egg weights are attributed partially to female body size differences. RE varies interspecifically perhaps as a result of differential habitat productivity. Intraspecifically, clutch size but not RE was positively correlated with body size. Intraspecific RE variation patterns differ among species. Egg weight-body weight correlation was not significant for the four larger species; however, egg weight was positively correlated with body weight in the smallest species. Smaller species also produced relatively larger eggs. A minimum egg size in Cnemidophorus is suggested. Whiptail RE's are difficult to measure because important costs such as courtship, mating, carrying eggs and locating suitable nest sites are not easily quantified. The reproductive cycle is similar in all species. Males emerge from brumation with enlarged testes which decrease in volume throughout the summer. Females emerge with yolked follicles. Fat bodies are small in in both sexes early in the season, continue to drop during the summer, and rebuild after reproduction ceases. Males possess femoral pegs most commonly during the reproductive season. No difference between bisexual and parthenogenetic species was observed. Unisexual species may simply resemble one of their bisexual parental species. Cnemidophorus reproductive characteristics depend on their body size and ecological position as fast moving, widely foraging species. Such factors could overshadow differential selection operating on the reproductive characteristics of weedy parthenogenetic and nonweedy bisexual species.

The Ovarian Cycle, Reproductive Potential, and Structure in a Population of the Japanese Lacertid Takydromus tachydromoides

A three year study of a population of Takydromus tachydromoides in central Honshu, Japan revealed that yolk deposition in follicles of juvenile lizards begins in the late spring following their first hibernation, at a body length exceeding 41 mm. Adult females emerge from hibernation with yolked follicles. Oviposition of first year lizards begins in early June, reaches a maximum in July and ends before mid-August. Older females begin oviposition in early May, reach their peak in the first half of June, and cease laying in late July. In experimental lizards corpora lutea regressed from an average of 2.1 mm on the day of oviposition to 1.0 mm five days postoviposition. These persist as corpora albicantia apparently for the life of the lizard. Estimates of age groupings by counts of corpora albicantia suggests that first year females contain none in spring and 4-13 in fall; second year lizards, 1-12 in spring and 14-26 in fall; third year females, 14-23 in spring and 26-39 in fall; and fourth year females, 31-40 in spring and 51-69 in fall. The incidence of corpora albicantia in adult lizards collected from 15 August until hibernation is 97%. Clutch size of first year lizards ranges from 1 to 4 for all clutches, with means of 2.6 for the first clutch and 2.4 for the second and third. Clutches

Studies on Reproduction in Costa Rican Ameiva festiva and Ameiva quadrilineata (Sauria: Teiidae)

Male and female Ameiva festiva and A. quadrilineata from Pandora, Costa Rica appear to be reproductively active throughout the year. Mean clutch sizes determined by counts of yolked follicles were 2.29 in A. festiva and 2.05 in A. quadrilineata. Based upon counts of oviducal eggs and/or corpora lutea these averages were 2.22 in A. festiva and 2.07 in A. quadrilineata. No significant increase in clutch size in Ameiva was apparent with an increase in body size. Interuterine migration of eggs was common in both species. Follicular atresia was frequently observed in field samples of both species. Fat body percentages of the total body weight ranged in pooled samples from 0.10 to 2.39 in female A. festiva and from 0.10 to 2.55 in female A. quadrilineata. These percentages ranged from 0.05 to 1.09 in male A. festiva and from 0.07 to 0.89 in male A. quadrilineata. The interval between the initiation of deutoplasmic activity in a set of follicles and ovulation is approximately eight weeks in both species. Oviposition occurs 17-21 days after ovulation.