We evaluated helminth parasitism in the alien frog, Polypedates leucomystax, on Ishigakijima and Iriomotejima, Yaeyama Islands, Okinawa, Japan. Among 12 helminth species observed, the parasitic oligochaete, Allodero sp., may have been introduced by this frog to Ishigakijima without spreading to Iriomotejima. Raillietnema rhacophori, a nematode commonly parasitic in P. leucomystax of Okinawajima and Miyakojima, was not observed. Seven helminth species, namely, Mesocoelium sp., Rhabdias sp., Strongyloides sp., Cosmocerca japonica, Meteterakis sp., Oswaldocruzia hoepplii, Oswaldocruzia japalurae, Pseudoacanthocephalus sp. were surmised to be acquired from the endemic anurans and/or saurians in the Yaeyama Islands. This frog also serves as a paratenic host for Physalopteridae sp., Dispharynx sp. and Centrorhynchus sp./spp., in which adults are parasites of birds or snakes.
Habitat fragmentation is one of the major threats to amphibian species. In a previous study, population genetic analyses of the Japanese brown frog Rana japonica were conducted using a mitochondrial DNA (mtDNA) marker in a typical Japanese agricultural landscape (known as satoyama) in Chiba, Japan. This previous study revealed that gene flow was restricted by the roads and cement-walled urban river that divide this site. In the present study, we reanalyzed the genetic structure of the same meta-population using microsatellite markers in comparison with the mtDNA results and elucidated fine-scale gene flow. The genetic structure derived from the microsatellite clustering analysis was almost identical to that of the mtDNA results, although some important details differed. We recognized boundaries of genetic structure are consistent with the major roads and cement-walled river, however, we also detected gene flow across those artificial barriers. We concluded that the current genetic structure was formed in the past when gene flow was strongly restricted. Gene flow among breeding populations is now being restored by the maintenance of breeding sites, although it is not sufficient to erase the signature of historical isolation.
The Japanese giant salamander, Andrias japonicus, is known to exhibit very low genetic diversity, but the number of individuals surveyed in a population is limited by now. We investigated partial sequences (673 bp) of mitochondrial cytochrome b gene in 180 specimens of a population from the Inuyama Head Works on the Kiso River, Central Japan, over nine years so as to clarify the degree of genetic diversity. The result again confirmed a tendency of lack of diversity; only one individual differed from the remaining 179 with an uncorrected p-distance of only 1.5%. The individual had the sequence identical with that reported for an individual from San’in District of Western Japan, far from the Kiso River, and is thought to have been introduced artificially. The healthy condition of the salamander population in spite of highly reduced genetic diversities might be due to possible decrease of inbreeding depression, resulting from the past purging effect of ancestral inbreeding wherein deleterious recessive alleles were eliminated from the gene pool.
Although Fejervarya kawamurai is a common frog in the paddies of western Japan, their larvae seem to be scarce in the paddies where larvae of Hyla japonica and Pelophylax nigromaculatus are abundant. To examine the cause of this phenomenon, we surveyed the reproductive season of these three species at two sites with different irrigation schedules using an automatic recording system. In addition, we conducted several experiments to test three possible explanations; (1) maternal avoidance from P. nigromaculatus larvae in the selection of oviposition site, (2) predation on F. kawamurai eggs by P. nigromaculatus and the larvae of other species, and (3) negative interactions of P. nigromaculatus larvae on the larvae of F. kawamurai. In paddies flooded throughout the year, calling of H. japonica and P. nigromaculatus started far earlier than in F. kawamurai, whereas in paddies irrigated in mid-May, these three species started calling simultaneously. We found significant predation pressures on F. kawamurai eggs from larvae of H. japonica, Rana japonica, P. nigromaculatus, P. porosus brevipodus, Glandirana rugosa, F. kawamurai, and Rhacophorus schlegelii, whereas no significant predation pressures from larvae of B. japonicus was detected. We found no evidence of maternal choice by F. kawamurai for oviposition sites and no effects of P. nigromaculatus larvae on sympatric larvae of F. kawamurai. Our results suggest the possibility that the mortality rate of F. kawamurai eggs might increase through predation at paddies where H. japonica and P. nigromaculatus start oviposition earlier than does F. kawamurai.
Agassiz’s desert tortoise (Gopherus agassizii) reaches the southern edge of its range in the Sonoran Desert of California. The reproductive ecology of this wide-ranging species is understudied here compared to populations in the adjacent Mojave Desert. Understanding potential geographic variation in reproductive ecology is important for effective management of conservation-reliant species like G. agassizii. We studied the fecundity and clutch phenology of female G. agassizii at two study sites in the Sonoran Desert region of Joshua Tree National Park over five years (1997–1999–2015–2016) spanning two of the strongest El Niño events on record and an epic drought. Across all years, mean clutch size was 4.3±1.5 eggs, mean clutch frequency was 1.78 clutches/female/year, and mean X-ray egg width was 36.51±1.56 mm, all of which are comparable to other published studies both in the Sonoran and Mojave deserts of California. Our results generally support earlier published findings that G. agassizii utilize a bet-hedging strategy of consistently producing small clutches almost every year, even during times of low annual primary productivity. A regionally warmer climate in the Sonoran Desert of California appears to have an effect on the timing of egg production, as the earliest dates of egg visibility in our study (April 6) were approximately two weeks earlier than the earliest dates reported for G. agassizii in the Mojave Desert. Shelled eggs were no longer visible in tortoises after mid-June in all years but the El Niño year 1998, when eggs were visible until mid-July.
Body size and age of two populations of the endangered species Pelophylax porosus porosus from the Kanto Plain, Japan (paddy fields in valley bottoms [Zushi] and open plains [Hayamajima]) were investigated. Age was estimated by skeletochronology of the phalanges. Frogs grew rapidly between 0 and 1 year of age in both populations. The asymptotic snout-vent length (SVL) of both sexes peaked at 2 years. Age at sexual maturity was estimated to be 0–1 years for males, but 1–2 years for females. SVL in adults ranged from 45.2 to 67.2 mm in males, and 60.2 to 88.8 mm in females. In both populations, females were significantly larger than males. However, the SVL was not significantly different between the populations or between age classes in both sexes. Lines of arrested growth (LAGs) were observed in the periosteal tissue. Longevity was estimated to be 3 and 4 years in males and females, respectively. Pelophylax p. porosus is suggested to be the most short-lived and the first to reach sexual maturity compared with the other Pelophylax species in Japan, although the age structure differed between the populations. In both sexes, when comparing the age of 1 year old or older frogs, the Zushi population was significantly older than the Hayamajima population, but the longevity of the Hayamajima population was shorter than that of the Zushi population. As the two study sites differed in agricultural management, it is possible that the resulting environmental conditions influenced the longevity of P. p. porosus.
Reproduction was studied in an invasive population of Anolis carolinensis in the Hawaiian Islands, USA. Timing of events in the reproductive cycle was similar between A. carolinensis populations in Hawaii and native populations of the species in the southeastern United States. In Hawaii, males of A. carolinensis undergo a prolonged period of spermiogenesis (sperm formation) starting in November (n=1) and December (n=1) and continuing into August. Gravid A. carolinensis females in Hawaii (n=40) produce one egg in continuous succession from March into August. Reproductive activity in A. carolinensis in Hawaii ceased prior to the colder, wetter, winter months.
Phalotris multipunctatus was previously only known from the type specimens collected from two widely disparate localities in the Cerrado of southeast and central Brazil over 36 years ago. Here, it is documented to occur in Paraguay from two specimens recently collected at the highly diverse Rancho Laguna Blanca. Live coloration is described and notes on unusual defensive behaviors are provided, along with the first live image of the species. It is considered highly likely that the species is critically endangered in Paraguay, and probably globally endangered. The importance of Rancho Laguna Blanca for the conservation of this poorly-known burrowing snake and other rare Cerrado reptiles is highlighted, along with the imminent threats to its existence.
Little is known about mating behaviors in arboreal snakes. We report three observations of mating in wild big-eyed pit vipers (Trimeresurus macrops) in northeast Thailand from 2013 to 2015. Mating occurred at the end of the rainy season, between 20 September and 28 October. One copulation occurred on the ground and two were arboreal (<1.5 m high). Females pulled males up trees during arboreal mating. Observations lasted from 2.2 to 12.9 h, but two of the three observations were initiated after copulation had started and were thus incomplete. Females were larger than males in all copulations. On one occasion a second male attempted to disrupt a mating pair using aggressive body movements and tail wrestling. All mating occurred in human disturbed forests, and two of them were observed in close proximity to human habitations.
The Javelin sand boa, Eryx jaculus, is one of the erycid snakes occurring in Iran. In order to investigate sexual dimorphism in this species, 12 morphological characters were examined in 22 adult specimens (10 males and 12 females) from different localities in western Iran. Results showed that the number of sub-caudal scales, the relative tail length, and snout-vent length are different between sexes. Brief comparison of sexual dimorphism among species of Eryx was presented.