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In the majority of temperate zone snakes, the mating season is temporally dissociated from the time of fertilization. Similarly, in males, the mating season is often temporally dissociated from spermatogenesis. In temperate zone pitvipers of North America, estrus, the time when females signal that they are receptive to males, occurs at some time during vitellogenesis. In these pitvipers, vitellogenesis is initiated in the late summer or fall. The vitellogenic follicles overwinter at an intermediate size, resume development in the spring, and culminate with ovulation in the spring. The seasonal patterns of estrus (late summer/fall or spring or both seasons) vary among species and rarely among populations within a species. In our model, we assume (i) that females determine the mating season, (ii) that there are significant costs to females during estrus, and (iii) that males adapt their mating season to the combined time when females enter estrus. We propose that the vitellogenic cycle of temperate zone pitvipers is simply a modification of the vitellogenic cycle seen in tropical pitvipers. The major difference being the interruption of vitellogenesis in temperate species by cold temperatures. In tropical pitvipers the vitellogenic cycle is continuous (no winter pause) and the mating season occurs at some time during vitellogenesis. As populations of pitvipers evolved into temperate climates, due to range expansion into temperate regions or climate change in existing ranges, the seasonal vitellogenic cycle was interrupted by winter. Since the mating season occurs during vitellogenesis, having a summer/fall and spring mating season is consistent with the tropical pattern. The different mating patterns we see today reflect a loss of either the summer/fall or the spring mating season. The reason for the loss may be due to the success of one mating season (all the females being fertilized) and the costs associated with having a redundant mating season. Since males also have significant costs associated with being prepared to mate, the loss of the female mating season would result in a corresponding loss of that season in males.
We conducted a nine-year mark-recapture study of a population of Crotalus viridis oreganus at a hibernaculum in north central Idaho from 1982 to 1990. Snakes were captured by hand and drift fence traps and individually marked. We made 627 recaptures from 319 marked snakes (176 males, 143 females). The primary sex ratio did not differ significantly from 1:1. Males were not significantly different in length or mass from females at birth. Estimated average individual growth rates in length beginning at birth (18.2 and 20.5 cm/yr for females and males, respectively) were not significantly different between sexes. However, males grew to a significantly longer estimated average asymptotic length (88.8 cm) than females (69.2 cm). The average annual growth rate in mass did not differ significantly between males and females (49 and 43 g/yr, respectively). The maximum snout– vent lengths of males and females in this study were 96.0 and 79.5 cm, respectively. Snakes underwent ecdysis two to three times during their first year and most shed two more times during their second year of growth. Most known-aged females reached sexual maturity in their fourth summer, but some males matured during their second summer. Clutch size varied from 3 to 8 young per female (mean = 4.8). The predominant female reproductive cycle was biennial. Three females showed an annual cycle, the first documentation of this in a temperate zone pitviper, but only for two successive years. Only one female had a confirmed triennial cycle, but we suspect that this was underestimated. The proportion of females in reproductive condition was significantly related to prey density of the prior year. Survival was highest for adults followed by immatures and newborn, and survival decreased for all age groups over the period of the study (from 82 percent to 55 percent for adults). The decrease in survival may be related to a handling or study effect.
We report on a small collection of parachuting frogs from Sumatra and Java. Three new species are described. Rhacophorus achantharrhena is similar to R. dulitensis and R. prominanus and differs from these species by a suite of characters including morphology of the supratympanic fold, digital webbing, coloration, and morphometrics. These three species are unusual in having white visceral and parietal peritonea. Rhacophorus catamitus is a small species similar to R. angulirostris and differing from this species by having a calcar at the heel and reduced digital webbing. Rhacophorus barisani resembles R. baluensis but differs from this species in color pattern, habitus, webbing of the fingers, and morphology of the dermal appendages. A new specimen of Sumatran R. pardalis is described and compared to the holotype of R. pulchellus. Rhacophorus prominanus is reported from Gunung Rajabasa, Lampung. Two specimens are described and compared to Bornean R. dulitensis and R. prominanus from the Malay Peninsula. Rhacophorus tunkui Kiew is a junior subjective synonym of Rhacophorus prominanus Smith. Finally, we describe new specimens of Rhacophorus margaritifer from Cibodas, Java. Skeletons of the new species and of R. margaritifer are described in detail. Superficial jaw and throat musculature appears to be relatively conservative within the genus.
The phylogenetic relationships among anoles have been much studied and difficult to unravel. Most work has focused on the Caribbean anoles, leaving the phylogenetic relationships among mainland anoles and the majority of Norops (beta Anolis) species virtually uninvestigated. A classification of series, subseries, and species groups within Norops was previously proposed and many workers in the field use this classification, despite a lack of understanding of the phylogenetic relationships within Norops. This paper reviews the taxonomic history and current status of Norops taxonomy. The focus of the study was to evaluate the monophyletic status of five previously described groups of Norops: the auratus, fuscoauratus, grahami, petersi, and sagrei series. Additional subgroupings below these levels were also investigated. The existing classification was tested by examining the relationships among Norops species using nuclear ITS-1 (internal transcribed spacer) DNA sequences. These data resulted in nine most parsimonious trees and supported only the monophyly of the sagrei series; the other four series do not appear monophyletic in these trees. However, in both maximum likelihood and Bayesian analyses the sagrei and grahami series were monophyletic, while the remaining three series (auratus, fuscoauratus, and petersi series) were not monophyletic. The monophyly of the grahami series could not be statistically rejected, but the remaining three series (auratus, fuscoauratus, and petersi series) were statistically rejected. In addition, the monophyly of two subseries and four species groups was statistically rejected, while the monophyly of one species group could not be rejected, and one subseries and three species groups were of ambiguous monophyletic status. The lack of support for these previously described series is not surprising given that the groups were erected largely on phenetic bases and are not observed when these data are analyzed cladistically. I propose continued recognition of the sagrei series, grahami series, and laeviventris species group, but I caution future workers to refrain from assigning species to other previously described groups until support for them is found, or a well supported alternative classification is proposed.
Previous systematic studies of the Bufo peltocephalus Group based on morphology and one on molecular data support the monophyly of this lineage of West Indian toads. Herein, additional phylogenetic evidence supporting the monophyly of the group is presented. Osteological, external morphological, and DNA sequence data were examined and combined to estimate the phylogenetic relationships of the West Indian B. peltocephalus Group (B. cataulaciceps, B. empusus, B. fluviaticus, B. peltocephalus, B. fustiger, B. guentheri, B. gundlachi, B. longinasus, B. lemur, and B. taladai). To assess the hypothesis of monophyly and estimate the placement of these species within Bufo, parsimony analyses including proposed close relatives and a taxonomically diverse sample of congeners were conducted. The nearest relatives of the West Indian toads appear to be the Bufo granulosus Group from South America.