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In this study, we investigated the use of wireless ultrasonography as an imaging system to study the reproductive ecology of the asp viper (Vipera aspis), a viviparous snake found in southwestern Europe. Female vipers were captured during the summer and immediately scanned to obtain an estimate of the number of embryos. Ultrasound imaging was performed with a pocket‐sized wireless ultrasound probe interfaced with a tablet with a dedicated app. Vipers were then released at the exact capture site after collecting data on body size and weight. We validate wireless ultrasonography as a non‐destructive, effective tool for ultrasonic investigations in the field. Wireless probes are light and compact, which facilitates carriage in rugged terrain. Moreover, the absence of cables simplifies the maneuvers to be made on a small, potentially dangerous snake. Importantly, ultrasound scans can be performed at the capture site, thus minimizing restraint time and handling of gravid females. Research Highlights: We establish wireless ultrasonography as an effective tool for animal fieldwork.Wireless ultrasound scanners are light and flexible and can be used in harsh environments where power sources are not accessible. [ABSTRACT FROM AUTHOR]

Quantification of genital variation in males and females can inform our understanding of likely copulatory interactions and evolution of genital diversity. However, no studies have quantified genital shape variation within a single snake species or examined the shape and size of both the vaginal pouch and hemipenes. Here, we examine the shape and size of the genitalia of female and male diamondback water snakes, Nerodia rhombifer , using a three-dimensional automated landmark geometric morphometric approach on models of the lumen of the vaginal pouch and inflated hemipenes, applying these techniques for the first time to the genital shape of vertebrates. Vaginal pouch shape is significantly associated with body size and reproductive status. As females grow larger and become reproductive, the vaginal pouch enlarges, widens and becomes more bifurcated. In reproductive males, the shape of the hemipenes is also significantly associated with body size. As males grow larger, the hemipenes enlarge and widen; their bifurcation becomes more defined and the spines at the base become more prominent. Vaginal pouch and hemipenial centroid size are isometric with respect to body length. The centroid sizes of the hemipenes and vaginal pouch are not significantly different from one another, hence the genitalia match in size. Reproductive females and males covary in the degree of bifurcation and size of their genitalia. We demonstrate the utility of three-dimensional analysis in studies of the shape of soft tissues and advocate its use in future studies of genitalia. [ABSTRACT FROM AUTHOR]

Studies on reproductive biology have largely contributed to the understanding of snake ecology. However, detailed reproductive data are scarce for many groups, particularly blind snakes. Here, we describe the reproductive biology of Trilepida koppesi (Leptotyphlopidae), a widely distributed species in the savannas of south-central Brazil. We describe its macro- and microscopic reproductive anatomy, female reproductive cycle, potential clutch size, seasonal activity, and sexual dimorphism of a population from south-eastern Brazil. Males have plurilobulated testes. Spermiogenesis occurs in early spring (October), when gonads and kidneys show a textured surface, the sexual segment of the kidney is hypertrophied, and the ductus deferentia are opaque and packed with sperm. Females have only the right oviduct, which shows developed epithelium and uterine glands in spring. Mating likely occurs in spring (October-December), and females store sperm in infundibular receptacles until ovulation between late spring and early summer. Potential clutch size ranges from three to five eggs. Females grow larger than males. The synchrony between spermiogenesis and mating defines the male cycle as prenuptial, which is considered the ancestral state of Squamata. These results agree with the hypothesis of conservative parameters for the group. [ABSTRACT FROM AUTHOR]

The morphological differences in female genitalia within and between species are little studied and poorly understood, yet understanding patterns of variation in female genitalia can provide insights into mechanisms of genital evolution. The present study aimed to explore the patterns of intraspecific and interspecific variation in female genitalia in two sister taxa of watersnake (Nerodia sipedon and Nerodia fasciata) that have similar genital shape. We used a geometric morphometric (GM) approach to study variation in shape of the vagina between and within two sister species. We examined genital shape in female watersnakes ranging from small, sexually immature females to large reproductive females that had recently given birth. We found that shape variation of genitalia is strongly correlated with body size, where larger but not smaller females have a bifurcation in the vagina. However, we also found significant shape variation in the structure of the vagina between the two species, where N. fasciata has narrower genitalia with more prominent bifurcation, whereas N.sipedon has wider genitalia with less marked bifurcation. Using GM allowed us to detect significant differences in genital shape that were not apparent upon visual examination alone, suggesting that shape variation in female genitalia may be greater than previously assumed. Additional study of morphological differences in male reproductive organs for these species would help to determine whether there has been genital co-evolution, and potentially mechanical reproductive isolation, in these two closely-related and occasionally sympatric species. © 2013 The Linnean Society of London.

The morphological differences in female genitalia within and between species are little studied and poorly understood, yet understanding patterns of variation in female genitalia can provide insights into mechanisms of genital evolution. The present study aimed to explore the patterns of intraspecific and interspecific variation in female genitalia in two sister taxa of watersnake (Nerodia sipedon and Nerodia fasciata) that have similar genital shape. We used a geometric morphometric (GM) approach to study variation in shape of the vagina between and within two sister species. We examined genital shape in female watersnakes ranging from small, sexually immature females to large reproductive females that had recently given birth. We found that shape variation of genitalia is strongly correlated with body size, where larger but not smaller females have a bifurcation in the vagina. However, we also found significant shape variation in the structure of the vagina between the two species, where N. fasciata has narrower genitalia with more prominent bifurcation, whereas N.sipedon has wider genitalia with less marked bifurcation. Using GM allowed us to detect significant differences in genital shape that were not apparent upon visual examination alone, suggesting that shape variation in female genitalia may be greater than previously assumed. Additional study of morphological differences in male reproductive organs for these species would help to determine whether there has been genital co-evolution, and potentially mechanical reproductive isolation, in these two closely-related and occasionally sympatric species. © 2013 The Linnean Society of London.

The author presents a personal narrative of his experiences of traveling India to examine King Cobra, and discussed topics including mating season of king Cobra, Madras Crocodile Bank, India and Snake fishing.

Emergent diseases may result in population declines by inducing mortality directly or through sublethal effects on host reproduction. Snake fungal disease (SFD) is an emerging threat to biodiversity, but the sublethal impacts of disease on host fitness are poorly characterized. The cryptic nature of most snakes makes direct assessment of the fitness consequences of SFD challenging. In such contexts, measurement of sex steroids that correlate positively with seasonal reproductive investment may be useful in inferring the scope of disease impacts. To test the hypothesis that SFD is associated with reproductive suppression, we measured testosterone and estradiol in free‐ranging pygmy rattlesnakes with varying clinical signs of SFD. We also used real‐time PCR to validate the relationship between clinical signs and Ophidiomyces ophiodiicola (Oo) DNA presence on the skin. Infected males had lower testosterone compared to uninfected males during summer spermatogenesis and the fall breeding season. Infected females were less likely to have elevated estradiol compared to uninfected females during spring vitellogenesis. Approximately 85% of individuals with clinical signs were positive for Oo DNA. Our findings are consistent with the hypothesis that coping with SFD comes at a cost to the reproductive success of afflicted individuals, and that seasonal sex steroids may be valuable early indicators of sublethal effects. Snake fungal disease (SFD) is associated with suppression of sex steroid hormones in Pygmy rattlesnakes, Sisturus miliarius. Steroid suppression in infected males and females was only evident during seasonal reproductive events. SFD infection likely has associated sublethal reproductive costs in male and female rattlesnakes. [ABSTRACT FROM AUTHOR]

Animal movements govern most ecological interactions, from predation to reproduction and survival. How animals move through the environment depends on available sensory information. Some snakes are able to perceive infrared (IR) radiation in addition to visible light. Research on this sensory system has been almost exclusively focused on predation, and researchers have largely found that vision and IR compensate for each other when one or the other is absent. However, IR sensing likely has much broader functions, including navigation in the environment. Many features in the environment of pit vipers are both visually and thermally salient and could be used for orientation. Here, we tested how vision and IR sensing interact in sidewinder rattlesnakes, Crotalus cerastes , in a simple navigation task in the field. Unlike in a predatory context, IR sensing did not compensate for the lack of vision. Snake movement paths were more tortuous, and snakes were less likely to encounter landmarks when eyes where occluded but were unaffected when pit organs were occluded. These findings suggest that the interaction between visual and IR cues may depend on context, and have important implications for our understanding of the evolution of IR sensing. Highlights • Rattlesnakes can see both infrared (IR) and visible light. • We tested whether snakes use thermal vision to find warm bushes at night. • We blocked IR organs and/or eyes and observed snake movement paths in an arena. • Snakes relied heavily on their eyes, and not pit organs, to find their way at night. [ABSTRACT FROM AUTHOR]

The Serra da Mantiqueira is one of the least inventoried physiographic areas of southeastern Brazil. There is great potential for detection of endemic species for which little or nothing is known about basic aspects of natural history. The Parque Estadual da Serra do Papagaio (PESP) within the Serra da Mantiqueira is an area of extreme biological importance because it houses mixed formations of grasslands, ombrophilous forests, and enclaves of Araucaria forests (mixed ombrophilous forest). Currently, the mixed ombrophilous forest covers less than 5% of its original range and areas occupied by this forest type, and associated ecosystems constitute refuges, housing several endemic, high altitude species. Between September 2015 and April 2016, field samplings were performed in the PESP using four distinct methods. The objective was to determine the composition and natural history of snakes from an isolated, high altitude area of the Serra da Mantiqueira. In PESP and surrounding areas, 80 individuals representing 24 species, 19 genera, and three families were recorded. Data are presented on abundance, habitat, daily activity, diet, reproduction, and defense. Comparison of the PESP snake assemblage with 30 other Atlantic Forest areas in southeastern Brazil indicate the Serra da Mantiqueira presents particular characteristics regarding snake composition. [ABSTRACT FROM AUTHOR]

To comprehend the state of the art of sponge reproduction science (SRS), we quantified and analyzed the trends in SRS in the last decade, aiming to answer three questions: (i) Were there fewer SRS works presented during the last sponge conference? (ii) Did the number of SRS publications decline in the last decade? (iii) Does the number of abstracts at sponge conferences influence overall SRS publications? In addition, we checked whether the SRS community has answered Ereskovsky's 'five important questions', enabling us to advance SRS enough to be considered as a fourth period of this scientific field. We found that SRS was less represented at the last sponge conference, despite an increase in the number of publications during the last decade. Moreover, the number of abstracts presented at sponge conferences contributed to a small portion (25%) of the published works in this area during the last decade. In addition, we found that two of the five Ereskovsky's questions are still mostly not answered. Thus, we conclude that SRS is healthy and advancing steadily, especially in some subareas (e.g. developmental biology and life history). There are still much to advance, but this is still a strong field of biological science research. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we describe the female reproductive cycle of Philodryas patagoniensis in south Brazil, which was described through morpho‐anatomical and histological analyses. The peak of secondary vitellogenesis occurred during winter–spring (July–December), ovulation in spring (October–December), mating and fertilization in spring–summer (October–February), oviposition in spring–autumn (October–May) and births from late spring to autumn (December–July). The diameter of vitellogenic follicles/eggs was larger in winter–spring than in other seasons. The diameter of the shell glands was also larger in winter–spring. In spite of the clear reproductive peak, gonads only showed reduced activity in the autumn. Therefore, at the individual level, females have a discontinuous cyclical reproduction; in the populational level, the reproductive cycle is seasonal semisynchronous. We support the hypothesis that P. patagoniensis have the ability to produce multiple clutches with long‐term stored sperm. Sexual dimorphism in body size was evident, and females are significantly larger and heavier than males. Larger females were able to produce follicles and eggs in larger amount and size. The maternal body size was positively related to the reproductive effort and fecundity. To conclude, we deliberated about the proximal and distal causes that influence the reproductive traits and patterns of P. patagoniensis. [ABSTRACT FROM AUTHOR]

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 environmental conditions. Neonate body size varied between sites, indicating that local selection may act through predation pressure, prey availability, or other environmental variables. Local selection may lead to differences in life history traits, whereas annual variation in factors such as prey availability might influence reproductive traits. Our study highlights the need for long-term studies to understand the sources of variation in life history. [ABSTRACT FROM AUTHOR]

This article examines Nicander's description of the mating habits of the viper as an example of how his biological information and his literary engagement with earlier Greek poetry influence each another. Nicander claims that female vipers kill their mates during copulation, and are then in turn killed by their babies during childbirth, "avenging" their father's death. I trace the intertexts that shape the passage from Herodotus to Aeschylus to Lycophron. Allusions to these authors allow Nicander to draw parallels between the violent reproductive cycle of vipers and literary succession of Hellenistic poets engaging with Classical authors of the past. [ABSTRACT FROM AUTHOR]

The freshwater sponge collections of the National Museum of Natural History of Madrid were examined and the presence of Eunapius carteri (Bowerbank, 1863) in the Iberian Peninsula was rediscovered. An approach to its ecology is also presented. This species is not currently considered within the Iberian and Western European fauna. Therefore, its rediscovery changes the conception of this species' biogeographical distribution in Europe linked to its ecology. [ABSTRACT FROM AUTHOR]

Despite the common assumption that most Haplosclerida are viviparous sponges, this study of the reproductive cycle of Haliclona fulva demonstrates that this species is actually oviparous and gonochoric. Intriguingly, not a single male was recorded in 15 months of sampling. Oogenesis is synchronous, starting in late April and terminating in September. Asexual reproduction is represented by cyclic budding, which occurs from late November to early March. During the season of asexual reproduction, the reproductive effort represents from 0.21% to 1.49% of the parental tissue, with the highest values being recorded in winter. During the season of sexual reproduction, the female reproductive effort ranges 0.05-1.15%, with the highest effort appearing in early summer. However, no significant correlation between reproductive efforts and seawater temperature fluctuations could be detected. We describe the ultrastructural morphogenesis of the buds for the first time in this species. This process is asynchronous, with buds of variable size being attached to the maternal apical surface via a short stalk. Young buds lack any particular anatomical organization, whereas bud maturity is characterized by the development of mesohyl and by the appearance of an increasing number and volume of lacunae in the central part of each bud. At this stage, buds harbor numerous small choanocyte chambers scattered throughout the inner region, and all cell types known from the mesohyl of parental sponges: microgranular cells, granular cells, archaeocytes, endopinacocytes and exopinacocytes, central cells, and sclerocytes. [ABSTRACT FROM AUTHOR]

Background: The oviparity-viviparity transition is a major evolutionary event, likely altering the reproductive process of the organisms involved. Residual yolk, a portion of yolk remaining unutilized at hatching or birth as parental investment in care, has been investigated in many oviparous amniotes but remained largely unknown in viviparous species. Here, we used data from 20 (12 oviparous and 8 viviparous) species of snakes to see if the oviparity-viviparity transition alters the partitioning of yolk in embryonic snakes. We used ANCOVA to test whether offspring size, mass and components at hatching or birth differed between the sexes in each species. We used both ordinary least squares and phylogenetic generalized least squares regressions to test whether relationships between selected pairs of offspring components were significant. We used phylogenetic ANOVA to test whether offspring components differed between oviparous and viviparous species and more specifically, the hypothesis that viviparous snakes invest more in the yolk as parental investment in embryogenesis to produce more well developed offspring that are larger in linear size. Results: In none of the 20 species was sex a significant source of variation in any offspring component examined. Newborn viviparous snakes on average contained proportionally more water and after accounting for body dry mass, had larger carcasses but smaller residual yolks than did newly hatched oviparous snakes. The rates at which carcass dry mass (CDM) and fat body dry mass (FDM) increased with residual yolk dry mass (YDM) did not differ between newborn oviparous and viviparous snakes. Neither CDM nor FDM differed between newborn oviparous and viviparous snakes after accounting for YDM. Conclusions: Our results are not consistent with the hypothesis that the partitioning of yolk between embryonic and post-embryonic stages differs between snakes that differ in parity mode, but instead show that the partitioning of yolk in embryonic snakes is species-specific or phylogenetically related. We conclude that the oviparity-viviparity transition does not alter yolk partitioning in embryonic snakes. [ABSTRACT FROM AUTHOR]

Understanding of snake ecology has increased over the past two decades, but is still limited for many species. This is particularly true for the recently described Beni anaconda (Eunectes beniensis). We present the results of a radio-telemetry study of nine (3M:6F) adult E. beniensis, including home range, and habitat use. We located the snakes 242 times in wet season, and 255 in dry season. Mean wet season home range (MCP) was 25.81 ha (6.7 to 39.4 ha); while mean dry season home range was 0.29 ha (0.13 to 0.42 ha). We found no relationship between home range size and either snout-vent length, weight, or sex. Beni anacondas seem to prefer swamps, and patujusal, while avoiding forest, and rice fields. However, habitat use by individual snakes seems to vary based on the habitats available within their respective home range. Notably, rice fields were avoided by most snakes, which suggests that this type of habitat is unsuitable for anaconda management. [ABSTRACT FROM AUTHOR]

The male reproductive cycle of Philodryas patagoniensis in south Brazil was described through morpho-anatomical and histological analysis of individuals deposited in zoological collections. Spermatogenesis occurred during late autumn-winter (June-September) and spermiogenesis occurred in spring-summer (October-March). The volume of the testes was smaller (quiescent) in winter, while the tubular diameter and the epithelial height of the seminiferous tubule were larger in summer (January-March). The ductus deferens presented spermatozoa all over the year and had no seasonal variation in diameter. The length of the kidney was larger in winter-spring (July-December), although the tubular diameter and epithelium height of the sexual segment of the kidney ( SSK) were larger only in winter (July-September). Total testicular regression was observed in late autumn (May), simultaneously with the peak in SSK. Therefore, at the individual level, males exhibit a discontinuous cyclical reproduction. Considering the population level, the reproductive cycle is seasonal semisynchronous, with most of the individuals showing a reproductive peak in spring-summer (October-March). Here, we present evidence to support the importance of the microscopic approach to reproductive cycle studies. Finally, we discuss the intrinsic and extrinsic factors influencing P. patagoniensis reproductive patterns. [ABSTRACT FROM AUTHOR]

We investigated the characteristics of a small smooth snake population in central Germany after it experienced a rapid loss of habitat between 1955 and 1990. We hypothesised that local smooth snakes might demonstrate abnormalities in population characteristics such as age of maturity, growth rates, sex-ratio, reproduction, movement behaviour or in population density, indicating degradation. To address this issue, we analysed data of a 17-year visual encounter survey (VES) accompanied by mark-recapture methods and complemented by a short-term radiotelemetry study of nine adult snakes. We then compared the population and behavioural characteristics with those from other European smooth snake populations. Our results indicated a healthy population despite the severe habitat loss. The population was characterised by a balanced sex-ratio and large litter sizes. Gender specific differences in migration behaviour and home ranges were typical for this species. However, the home ranges were unusually small which agrees with the noticeably high population density and the short time periods tracked. Although adult migration to adjacent habitats was never detected, some migration to and from other suburban sites likely occurred, evidenced annually by the high rate of first-captures of previously unregistered adults. Our results suggested that even a very small area could be sufficient for the survival and maintenance of a viable population of smooth snakes if the habitat provides a high abundance of essential microhabitats. Comparing our population variables with those from other studies help (1) to reduce potential threats at a regional level and (2) to define specific conservation actions for the population. [ABSTRACT FROM AUTHOR]

Male animals should preferentially allocate their time to performing activities that promote enhancing reproductive opportunity, but the need to acquire resources for growth and survival may compete with those behaviors in the short term. Thus, behaviors which require differing movement patterns such as ambushing prey and actively searching for mates can be mutually exclusive. Consequently, males that succeed at foraging could invest greater time and energy into mate searching. We radio-tracked sixteen male massasauga rattlesnakes ( Sistrurus catenatus) and supplemented the diets of half the snakes with mice across an active season. We tested the predictions that reduced foraging needs would allow fed snakes to move (i.e., mate search) more, but that they would consequently be stationary to thermoregulate less, than unfed controls. Contrary to our first prediction, we found no evidence that fed snakes altered their mate searching behavior compared to controls. However, we found controls maintained higher body temperatures than fed snakes during the breeding season, perhaps because fed snakes spent less time in exposed ambush sites. Fed snakes had higher body condition scores than controls when the breeding season ended. Our results suggest the potential costs incurred by devoting time to stationary foraging may be outweighed by the drive to increase mating opportunities. Such instances may be especially valuable for massasaugas and other temperate reptiles that can remain inactive for upwards of half their lives or longer in some cases, and for female rattlesnakes that generally exhibit biennial or more protracted reproductive cycles. [ABSTRACT FROM AUTHOR]

Broad phylogenetic patterns in sexual size dimorphism ( SSD) are shaped by sex differences in net selection pressures (e.g. sexual selection, fecundity selection, survival selection), but environmental and ecological factors can also affect the expression of SSD., Discussions of proximate ecological influences on SSD have focused on niche divergence; for example, increase in a prey type used by only one sex can elevate growth rates of that sex but not the other. Food limitation also can generate spatial and temporal variation in SSD. Under restricted prey abundance, curtailed growth may mask SSD even if the optimal size is greater for one sex than the other. Because an increase in food availability elicits increased feeding and growth by the sex that benefits more from increased body size, variation in prey abundance can generate variation in SSD., We used mark-recapture methods to study growth rates relative to prey (frog) abundance in two species of sexually dimorphic colubrid snake species in tropical Australia., In slatey-grey snakes ( Stegonotus cucullatus), a species in which larger body size enhances reproductive output in both sexes (because larger males win combat bouts, and larger females produce more/heavier eggs), increased abundance of frogs caused equivalent increases in growth rates in both sexes and hence did not affect SSD. In keelbacks ( Tropidonophis mairii), a species in which larger size enhances reproductive output in females more than males (reflecting a lack of male-male combat), increased abundance of frogs elicited higher growth rates of females only. Thus, SSD in keelbacks was modified by prey abundance., Our results show that the magnitude of sex differences in adult body size can be influenced by proximate environmental factors and support the hypothesis of sex-specific targets for maximum feeding rates., A is available for this article. [ABSTRACT FROM AUTHOR]

ABSTRACT Early amniotic vertebrates evolved large-yolked eggs that permitted production of well-developed, terrestrial hatchlings. This reproductive pattern required new mechanisms for cellularizing the yolk and mobilizing it for embryonic use. In birds, cells that line the yolk sac cavity phagocytose and digest the yolk material, a pattern that is commonly assumed to be universal among oviparous amniotes. However, recent evidence challenges the assumption that all squamate reptiles conform to the avian developmental pattern. In this paper, scanning electron microscopy and histology were used to study mechanisms of yolk processing in two colubrid snakes, the kingsnake Lampropeltis getula and the milksnake L. triangulum. Endodermal cells from the yolk sac splanchnopleure proliferate massively as they invade the yolk sac cavity, forming elaborate chains of interlinked cells. These cells grow in size as they phagocytose yolk material. Subsequently, vitelline capillaries invade the masses of yolk-laden cells and become coated with the endodermal cells, forming an elaborate meshwork of cell-coated strands. The close association of cells, yolk, and blood vessels allows yolk material to be cellularized, digested, and transported for embryonic use. The overall pattern is like that of the corn snake Pantherophis guttatus, but contrasts markedly with that of birds. Given recent evidence that this developmental pattern may also occur in certain lizards, we postulate that it is ancestral for squamates. Studies of lizards, crocodilians, and turtles are needed to clarify the evolutionary history of this pattern and its implications for the evolution of the amniotic (terrestrial) vertebrate egg. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate two research hypotheses: H 0 –the embryonic pancreas in grass snakes develops in the same manner as in all previously investigated amniotes (from three buds) and its topographical localization within the adult body has no relation to its development; H 1 –the pancreas develops in a different manner and is related to the different topography of internal organs in snakes. For the evaluation of these hypotheses we used histological methods and three-dimensional (3D) reconstructions of the position of the pancreatic buds and surrounding organs at particular developmental stages and of the final position and shape of the pancreatic gland. Our results indicate that the pancreas primordium in the grass snake is formed by only two buds – a dorsal and a ventral one – that are not connected until the end of stage II. This differs from the majority of vertebrates investigated so far. The gall bladder of the grass snake embryos is connected with the liver only by a thin cystic duct, which also differs from many other vertebrates. Our histological study also indicates a different distribution of the endocrine cells in the embryonic pancreas of the grass snake because the first endocrine cells appeared in the dorsal part of the pancreas in a region located close to the spleen. During the entire developmental period no evidence of these cells was found in the ventral part of the pancreas. The endocrine cells form elongated, large and irregular-shaped islets. They can also form structures resembling “inverted acini”. Such an arrangement is characteristic of snakes only. The differentiating pancreas penetrates the ventral part of the developing spleen and divides it into three separate parts at developmental stage IX. This is unique among vertebrates. At the end of the embryonic development (stage XI), the pancreas, the spleen and the gall bladder are located in close proximity and form the so-called triad. Our results suggest that the untypical topography of the organ systems in snakes may determine the unique development of the pancreas in these animals. [ABSTRACT FROM AUTHOR]

The article reports on the oviposition, the act of laying eggs, by Thelotornis kirtlandii snake in an ant nest. Topics mentioned include the importance of thermoregulation in snake to maintain high and balanced body temperatures throughout their active period, the multiple reproduction seasons for snakes, and the incubation of snake eggs.

One of the current challenges of evolutionary ecology is to understand the effects of phylogenetic history ( PH) and/or ecological factors ( EF) on the life-history traits of the species. Here, the effects of environment and phylogeny are tested for the first time on the reproductive biology of South American xenodontine snakes. We studied 60% of the tribes of this endemic and most representative clade in a temperate region of South America. A comparative method (canonical phylogenetic ordination- CPO) was used to find the relative contributions of EF and PH upon life-history aspects of snakes, comparing the reproductive mode, mean fecundity, reproductive potential, and frequency of nearly 1,000 specimens. CPO analysis showed that PH or ancestry explained most of the variation in reproduction, whereas EF explained little of this variation. The reproductive traits under study are suggested to have a strong phylogenetic signal in this clade, the ancestry playing a big role in reproduction. The EF also influenced the reproduction of South American xenodontines, although to a lesser extent. Our finding provides new evidence of how the evolutionary history is embodied in the traits of living species. [ABSTRACT FROM AUTHOR]

We describe two new aspects of male reproduction in the pit viper Bothrops cotiara: the formation of mating plugs and epididymal sperm storage. Based on histological analyses of specimens (four males and three females), we propose that long-term sperm storage occurs in the ductus deferens, whereas macroscopic hypertrophy indicates that the epididymis may be a short-term sperm storage site. Secretions of the sexual segment of the kidneys probably form the mating plug that males deposit in the female vagina during copulation. A mating plug without sperm was observed in the spring. Future studies should address the functions and longevity of mating plugs and the role of the epididymis in Bothrops reproduction. [ABSTRACT FROM AUTHOR]

Parthenogenesis occurs across a variety of vertebrate taxa. Within squamate reptiles (lizards and snakes), a group for which the largest number of cases has been documented, both obligate and facultative types of parthenogenesis exists, although the obligate form in snakes appears to be restricted to a single basal species of blind snake, Indotyphlops braminus. By contrast, a number of snake species that otherwise reproduce sexually have been found capable of facultative parthenogenesis. Because the original documentation of this phenomenon was restricted to subjects held in captivity and isolated from males, facultative parthenogenesis was attributed as a captive syndrome. However, its recent discovery in nature shifts the paradigm and identifies this form of reproduction as a potentially important feature of vertebrate evolution. In light of the growing number of documented cases of parthenogenesis, it is now possible to review the phylogenetic distribution in snakes and thus identify subtle variations and commonalities that may exist through the characterization of its emerging properties. Based on our findings, we propose partitioning facultative parthenogenesis in snakes into two categories, type A and type B, based on the sex of the progeny produced, their viability, sex chromosome morphology, and ploidy, as well as their phylogenetic position. Furthermore, we introduce a hypothesis (directionality of heterogamety hypothesis) to explain the production of female-only parthenogens in basal alethinophidian snakes and male-only parthenogens in caenophidian (advanced) snakes. [ABSTRACT FROM AUTHOR]

Reproduction involves costs and benefits to a female snake. Costs include increased predation risk as well as lower future survival and reproduction probability, whereas benefits are the current production of offspring. Reproduction also is highly energy demanding: at each reproductive event, a female must decide between the allocation of energy to female condition or to reproductive output. Moreover, energy allocation linked to reproduction may be influenced by environmental features, especially climate and food availability. During 2008 and 2009, we studied the female reproductive tactics of Thamnophis scaliger, a viviparous and earthworm-eating snake distributed at rather high altitudes in central México. Gravid females were collected in the field and maintained in captivity until giving birth. The low percentage of females that were gravid each year suggested they did not reproduce annually. This result probably was driven by the seasonal constrained availability and low-energy content of earthworms, which preclude females from acquiring sufficient energy to fuel more frequent reproduction. Females also produced rather large litter sizes, implying a significant investment in reproduction. Univariate and multivariate analyses (path analysis) found the expected relationships between maternal body size and litter size and mass, and there was no trade-off of energy allocation between postpartum females and their litters. We found, however, a noteworthy relationship between parturition date and postpartum female body condition. Females that reproduced later benefited most from foraging opportunities during the short rainy and high prey-availability period and remained in better body condition. La reproducción implica costes y beneficios para una hembra de ofidio. Los costes incluyen el aumento del riesgo a ser depredada, así como la disminución de la probabilidad de supervivencia y reproducción en el futuro, mientras que los beneficios son la producción de descendencia en el presente. La reproducción también demanda mucha energía, y cada vez que una hembra se reproduce, debe decidir entre la asignación de energía a su condición corporal postparto o al rendimiento reproductivo. Estas tácticas en la reproducción de los ofidios pueden estar condicionadas por factores medioambientales, especialmente el clima y la disponibilidad de alimento. En 2008 y 2009, estudiamos la táctica reproductiva de las hembras de Thamnophis scaliger, un ofidio vivíparo, especialista en el consumo de lombrices, distribuido a bastante altitud en el centro de México. Se colectaron hembras grávidas que se mantuvieron en cautividad hasta el parto. El bajo número de hembras grávidas cada año sugirió que no se reproducían anualmente. Este resultado estuvo probablemente condicionado por la estacionalmente limitada disponibilidad y el bajo contenido energético de las lombrices, que impiden a las hembras adquirir suficiente energía para una reproducción más frecuente. Además, las hembras produjeron camadas relativamente numerosas, lo que implica elevada inversión en reproducción. Análisis univariantes y multivariantes (análisis de vías) encontraron la esperada relación entre tamaño corporal materno, y el tamaño y peso de la camada, pero no hubo una compensación entre la energía asignada a las hembras postparto y sus camadas. Si encontramos una notable relación entre la fecha de parto y la condición postparto de las hembras. Las hembras que se reproducían más tarde se beneficiaban de mayor oportunidad de forrajeo durante el corto periodo lluvioso y de alta disponibilidad de presas, por lo que quedaban con mejor condición corporal. [ABSTRACT FROM AUTHOR]

Bothrops insularis is an endemic and critically endangered snake with an estimated population of 2000 individuals restricted to Queimada Grande Island, in southeastern Brazil. Brazilian researchers established a captive breeding program for the species that includes the application of assisted reproductive technologies. The present study, therefore, aimed to evaluate semen samples from captive B. insularis throughout the year to ascertain seasonal differences in semen traits as well as correlations with body size and weight. Eighteen males with snout-vent length (SVL) ranging from 43.5 to 73.7 cm were collected at quarterly basis between August 2012 and May 2013. Macroscopic analysis revealed semen volumes ranging from 0.5 to 6.0 μL with samples featuring whitish to yellowish color and creamy and thick consistency. Viable sperm was obtained from all males indicating that individuals with SVL equal to or greater than 43.5 cm are sexually developed. However, adult and immature males (estimated by SVL) exhibited different seasonal profiles for motility and progressive motility. Adult males had a decrease in sperm motility and progressive motility during summer and spring, respectively, whereas the same variables did not vary throughout the year in immature snakes. Sperm concentration in all individuals was less (0.5 × 10 9 μL) during the winter, but no seasonal fluctuations were detected in semen volume. These findings are of particular importance to the development of reproductive tools such as male selection, artificial insemination and sperm freezing for the genetic management of this critically endangered snake. [ABSTRACT FROM AUTHOR]

Aim Although most reptiles are oviparous, viviparity is a common mode of reproduction in squamates and has evolved multiple times in different lineages. We test two prevailing hypotheses regarding the biogeography of reptile reproductive modes to evaluate the selective forces driving the evolution of viviparity in snakes. The cold climate hypothesis posits that viviparity is selected for in cold climates, whereas the climatic predictability hypothesis predicts that viviparity is advantageous in seasonal climates. Location Global. Methods We collated detailed distribution maps and reproductive mode data for 2663 species of the world's terrestrial alethinophidian snakes. We studied the relationship between snake reproductive mode and environmental predictors. We applied both an ecological and an evolutionary approach to study snake reproductive mode by performing the analyses at the assemblage level and species level, respectively. We analysed our data at the global and continental scales to learn whether tendencies to viviparity are similar world-wide. Results We found strong support for the cold climate hypothesis and the assumption that viviparity is an adaptation to cold environments. There was little support for the climatic predictability hypothesis. Nonetheless, viviparous species are not restricted to cold environments. Main conclusions We conclude that viviparity is adaptive in cold climates, but not necessarily in unpredictable/seasonal climates. Current distributions may not reflect the climate at the time and place of speciation. We suspect many viviparous snakes inhabiting warm climates are members of lineages that originated in colder regions, and their occurrence in maladaptive environments is a result of phylogenetic conservatism. [ABSTRACT FROM AUTHOR]

Life-history theory predicts that organisms will hedge current reproductive investment against potential costs in terms of survivorship and future fecundity. However, little is known regarding the endocrine mechanisms underlying bet-hedging strategies in free-ranging male vertebrates. We examined the relationships among individual energetic status, steroid hormones, mate search, and reproductive behavior in free-ranging male timber rattlesnakes. Snakes were monitored over four active seasons in order to test two hypotheses: (1) males adjust the amount of time and energy allocated toward reproduction according to the level of individual energy stores, and (2) observed condition-dependent reproductive allocation is associated with circulating concentrations of steroid hormones (testosterone and corticosterone) thought to regulate reproductive behaviors in vertebrates. A positive relationship between body condition and testosterone was observed in both the field and the laboratory. Male mate search effort was positively correlated with both body condition and testosterone. Body condition and testosterone concentrations were negatively related to time allocated toward foraging during the breeding season. A strong effect of year was observed in the analysis of testosterone and search effort, suggesting that multiple environmental factors impact hormone production and reproductive investment. Corticosterone was not related to any measured variable. Therefore, our results did not indicate a clear role of corticosterone in mediating observed relationships between energetic status and behavior. Observed relationships are consistent with the hypothesis that males allocate time and energy toward reproduction according to individual energetic status and that testosterone plays a role in mediating the trade-off between current reproductive investment and residual reproductive value. [ABSTRACT FROM AUTHOR]

ABSTRACT The majority of lizards and snakes produce permeable parchment-shelled eggs that require high moisture conditions for successful embryonic development. One clade of gekkotan lizards is an exception; females produce relatively impermeable rigid-shelled eggs that normally incubate successfully under low moisture conditions. I tested the hypothesis that the rigid-shell increases egg survival during incubation, but only under low moisture conditions. To test this hypothesis, I incubated rigid-shelled eggs of Chondrodactylus turneri under low and under high moisture conditions. Eggs were incubated with parchment-shelled eggs of Eublepharis macularius to insure that incubation conditions were suitable for parchment-shelled eggs. Chondrodactylus turneri eggs had very high survival (>90%) when they were incubated under low moisture conditions. In contrast, eggs incubated under high moisture conditions had low survival overall, and lower survival than those of the parchment-shelled eggs of E. macularius. Mortality of C. turneri and E. macularius eggs incubated under high moisture conditions was the result of fungal infection, a common source of egg mortality for squamates under laboratory and field conditions. These observations document high survival of rigid-shelled eggs under low moisture conditions because eggs escape from fungal infection. Highly mineralized rigid shells also make egg survival independent of moisture availability and may also provide protection from small invertebrates in nature. Enhanced egg survival could thus compensate for the low reproductive output of gekkotans that produce rigid-shelled eggs. J. Exp. Zool. 323A: 607-615, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Snakes introduced to islands can be devastating to naïve native fauna. However, introduced populations must establish before range expansion (invasion) can occur. The factors that can determine successful invasion are those associated with the introduction event (e.g., characteristics of the founding population), the location (e.g., suitable environment and prey availability) and the species (e.g. life history characteristics). Here, we collected morphometric, ecological and genetic data on the recently introduced California Kingsnake ( Lampropeltis californiae) in Gran Canaria. We found that snakes occurring at two locations a few 10 s of km apart do not represent the same population. Genetic analyses confirmed significant genetic difference ( F = 0.184; D = 0.341), and that despite being inbred ( F = 0.245-0.257) the populations had high levels of diversity ( H = 0.485-0.490; allelic richness = 4.875-6.364). Snakes at the different Gran Canaria locations were significantly different in morphology (colouration, mass, length and age), fitness (egg production) and diet (rodents, skinks, lizards and geckos), supporting a hypothesis of separate founding groups in combination with local environmental heterogeneity leading to variation between these populations. We concluded that one population was more successful than the other in reproduction and recruitment, and may be having a greater impact on endemic reptiles. We recommend greater eradication effort for this population, as well as monitoring of local fauna at all locations to access the impact of predation. [ABSTRACT FROM AUTHOR]

There is a surprising lack of data available on snake demography. This is largely because snakes are cryptic and difficult to detect. To address this problem, researchers often use nonrandom sampling methods (which can result in sampling artifacts) or pool capture occasions (which results in a loss of information). We conducted two spatially and temporally overlapping mark-recapture studies on Milksnakes ( Lampropeltis triangulum). Both studies used fixed trap locations (artificial cover objects) but varied in their sampling duration and intensity. We used multimodel inference within an information-theoretic approach to estimate adult annual survival (0.72 ± 0.160 standard error [SE]) and abundance ( N = 85 ± 35.2 SE). To estimate density, we used a spatially explicit model (1.19 individuals/ha ± 0.331 SE). We applied a novel approach to address sampling bias that resulted from the use of fixed trap locations. This involved modeling maximum detection frequency as a covariate, which better accounted for individual heterogeneity in detection probabilities than did mixtures, sex, behavior, or month. This approach allowed for the recovery of information that was lost when capture occasions were pooled to account for low detection. We found support for this technique via reanalysis of datasets of known population size. This approach may be useful for mark-recapture studies that rely on fixed trap locations. [ABSTRACT FROM AUTHOR]

Studies of previous authors on snake skull embryogenesis have been performed on embryos obtained from eggs after oviposition. The aim of this study was to investigate the initial stages of chondrocra-nium development in Grass snake Natrix natrix Linnaeus, 1758, embryos before oviposition. Natrix natrix embryos at early developmental stages (24-27 according to the table of normal development by D. Zehr (1962)) were obtained by means of caesarean section. At developmental stages 25-27, previously undescribed structures were found in the region of future skull formation. These structures exist during one or two stages and then disappear. Therefore, we call them 'temporary structures.' The assumption about the nature of these structures is based on their topography and comparison with the structures of developing or fully formed chondrocranium in other vertebrates. It is hypothesized that the temporary structures in Natrix natrix chon-drocranium are vestiges of primary chondrocranium of ancestral vertebrate forms, and they indicate the exist-ence of several variants in the formation of chondrocranium in the historical vertebrates' development. [ABSTRACT FROM AUTHOR]

The article offers information the "New records of the Amazon banded snake Rhinobothryum lentiginosum (Serpentes: Colubridae) from Mato Grosso State, Brazil, with natural history notes" by the authors. Topics discussed include the distribution map of R. lentiginosum in the Brazilian state of Mato Grosso, reproductive study of males and females of species, and terrestrial and arboreal habits of the species.

Data on reproductive activity of fossorial species are limited because the specimens are difficult to be observed and captured. Here in, we present the reproductive cycle of female Atractus pantostictus, a fossorial neotropical species, and the sexual maturity of males and females in south-eastern Brazil. The female reproductive cycle of A. pantostictus is seasonal, with vitellogenic follicles being found from September to April and eggs in November, February, March and April with the number varying between two and four. Spermatozoa were found in the lumen of the glandular and non-glandular uterus in females collected during the rainy season. Sperm storage tubules were found in the posterior infundibulum of the females, where the storage of sperm occurs for a short time. The storage may occur because mating and ovulation are dissociated. [ABSTRACT FROM AUTHOR]

One popular concept used to explain the high biodiversity of some ecosystems is the Janzen-Connell hypothesis, which states that the distribution of conspecifics is controlled by species-specific pathogens or predators that are attracted to adults or to their reproductive output. The distribution of the affected species would then display a distinct pattern, with survivorship increasing at greater distance from the conspecific adult (negative density dependence), leaving a vacant area around the adult where other species can survive. The giant barrel sponge, Xestospongia muta, is an abundant and long-lived sponge on Caribbean coral reefs that is actively grazed by sponge-eating fishes and is susceptible to disease. We tested the Janzen-Connell hypothesis on barrel sponges on Conch Reef, Florida, by examining their distribution as a function of size using spatial point pattern analyses. Clark and Evans tests and a series of Ripley's K function analyses revealed no consistent distribution pattern, with most analyses resulting in a random pattern of sponge distribution. While predation by sponge-eating fishes has recently been discovered to structure sponge communities on reefs across the Caribbean, these top-down effects do not translate to spatial distributions of X. muta that support Janzen-Connell predictions. [ABSTRACT FROM AUTHOR]

We evaluated whether Batesian mimicry promotes early-stage reproductive isolation. Many Batesian mimics occur not only in sympatry with their model (as expected), but also in allopatry. As a consequence of local adaptation within both sympatry (where mimetic traits are favored) and allopatry (where nonmimetic traits are favored), divergent, predator-mediated natural selection should disfavor immigrants between these selective environments as well as any between-environment hybrids. This selection might form the basis for both pre- and postmating isolation, respectively. We tested for such selection in a snake mimicry complex by placing clay replicas of sympatric, allopatric, or hybrid phenotypes in both sympatry and allopatry and measuring predation attempts. As predicted, replicas with immigrant phenotypes were disfavored in both selective environments. Replicas with hybrid phenotypes were also disfavored, but only in a region of sympatry where previous studies have detected strong selection favoring precise mimicry. By fostering immigrant inviability and ecologically dependent selection against hybrids (at least in some habitats), Batesian mimicry might therefore promote reproductive isolation. Thus, although Batesian mimicry has long been viewed as a mechanism for convergent evolution, it might play an underappreciated role in fueling divergent evolution and possibly even the evolution of reproductive isolation and speciation. [ABSTRACT FROM AUTHOR]

Parent-offspring conflicts are likely to occur when resources are limiting either at pre- or post-natal stages due to intergenerational trade-offs over resources. Current theory posits that such conflicts may influence the evolution of parental allocation as well as reproductive modes. While energy allocation to the offspring has received considerable attention, the distribution of water - another potentially limited vital resource to both the mother and offspring - and the resulting outcomes remain grossly understudied., Here, we explored the intergenerational trade-off related to water resources in the viviparous aspic viper ( Vipera aspis) by examining the effects of water deprivation on female physiology (body mass, haematocrit and osmolality), water transfer to developing embryos and reproductive performance., As a result of water deprivation, females became dehydrated, with the effects more pronounced in pregnant compared to nonreproductive females. Among pregnant females, the impacts of water deprivation on water balance were correlated with fecundity. In contrast, water deprivation had no effect on water transfer to the offspring or on reproductive performance., Our results demonstrate that, under water-constraining conditions, female water balance is compromised in favour of the developing embryos, highlighting a significant intergenerational trade-off for water. Although ectothermic reptiles are particularly tolerant in water balance perturbations, our results suggest that, like energy, water can be a conflicting resource between mother and offspring. Parent-offspring conflict over water should therefore be further investigated to better understand reproductive modes and reproductive trade-offs in terrestrial organisms. [ABSTRACT FROM AUTHOR]

Among reptiles, reproduction in the absence of males is often assumed to result from long-term sperm storage. Through the application of molecular genetic tools, biologists are beginning to recognize that facultative parthenogenesis can also explain such reproductive events in snakes. We observed a Copperhead ( Agkistrodon contortrix) give birth to a stillborn neonate and four infertile ova after 9 yr in isolation from male snakes. To test the hypothesis that the neonate was produced asexually, we screened a panel of 10 microsatellite loci to genotype the mother and her offspring, as well as wild-caught individuals in the mother's population of origin, to assess the probability of paternity. Confirming prior research on Copperheads that suggests parthenogenesis by terminal fusion automixis, we found that four heterozygous maternal loci were homozygous in the neonate. We calculated the probability of a random male from the population as a sire to the neonate to be 2.32 × 10−13 by using the population allele frequencies and the genotype of the neonate. These results further confirm that Copperheads are facultatively parthenogenetic and suggest that this reproductive mode may be general within the species. [ABSTRACT FROM AUTHOR]

Pair-bonding between sexes is common in vertebrate taxa, yet it has been noted far less frequently in some groups such as reptiles, and snakes in particular. Evidence to date indicates that many snake mating-systems are polyandrous, with both males and females having multiple partners in a single breeding season, and thus unlikely to exhibit lengthy pair-bonds. Wittenberger and Tilson (1980) suggested that pair-bonding exists when pairs remain intact for a consecutive period equaling at least 25% of the breeding season. Using this criterion, we present evidence of pair-bond formation in a North American pitviper, Agkistrodon contortrix (Copperhead), a species with a polyandrous mating system. [ABSTRACT FROM AUTHOR]

European vipers are typical capital breeders and most studies have revealed that females usually reproduce once every two or three years and that, in some cases, females reproduce once during their lifetime. This paper presents evidence, based on monitoring marked snakes in consecutive years, that several female adders ( Vipera berus) from a montane environment from the Northern Romanian Carpathians reproduced annually (2007-2008), and also gives preliminary data on other female reproductive traits. Reproductive females and their offspring were smaller and lighter than V. berus individuals from most previously studied populations. Maternal traits were not significantly correlated with litter and offspring characteristics. [ABSTRACT FROM AUTHOR]

The article discusses the results of a field observation on the timing of reproduction of an Eastern small-eyed snake in coastal north Queensland. A brief information about the Eastern small-eyed snake's ecological behavior, impacts of climatic change to its diet and sexual reproduction is presented. It conclude that the Eastern small-eyed snake prefers in lowland tropical populations from September to December.

Steroid hormones regulate many aspects of reproductive physiology and behavior, including parental care. Reptiles display a variety of egg- and neonate-directed parental behaviors, yet few studies have addressed their endocrine correlates. Viviparous female pitvipers remain at the birth site with their young for one to two weeks until neonates complete their first shed cycle (‘ecdysis’). To study possible relationships between steroid hormones and these behaviors, we conducted a captive study on wild-caught pregnant cottonmouths. Females were divided into two treatment groups: Maternal Attendance (MA) – females were allowed a maternal attendance period, where neonates were left with the mother until they completed ecdysis and then were removed; Separated (SE) – females had their neonates removed within 24 h of birth. Serial blood samples were collected from MA females at various points during and after attendance; SE females had samples collected on a similar temporal schedule. Plasma levels of progesterone (P), estradiol (E2), testosterone (T), and corticosterone (CORT) were measured in all samples. We did not find a difference in the overall pattern of P, E2, or T between MA and SE females; however, MA females exhibited a significant peak in CORT on the day that neonates shed that was not observed in SE females. It is possible that the elevated CORT observed in MA females was stimulated by increased activity and/or changing chemical cues of shedding neonates. Based on evidence that free-ranging pitvipers cease MA when all offspring complete ecdysis, we hypothesize that CORT has a role in signaling mothers to terminate care and disperse. [ABSTRACT FROM AUTHOR]