Exploring the reproductive ecology of the tropical semifossorial snake Ninia atrata

Based on histological analyses and field studies,this research describes the reproductive ecology of a population of Ninia atrata snakes inhabiting an oil palm plantation.Furthermore,through a multivariate approach,we explored the main drivers of reproductive output in N.atrata.Results showed that prey abundance and food intake were crucial variables contributing to reproductive output.Multiple linear regression models showed that neonates had high sensitivity(R2=55.29%)to extreme changes in climate,which was strongly related to slug and snail abundance variability and microhabitat quality.Reproductive cycles were markedly different between the sexes,being continuous in males and cyclical in females.Despite this variation,reproductive cycles at the population level were seasonal semi-synchronous.Constant recruitment of neonates all year,multiple clutches,high mating frequency,and continuous sperm production characterized the reproductive phenology of N.atrata.In addition,a significant number of previtellogenic females presented oviductal sperm as well as uterine scars,suggesting a high precocity in the species.The main drivers of reproductive output also differed between the sexes.In females,clutch size and secondary follicle variability were highly related to stomach bolus volume,fat body area,and body mass.In males,height of piles of palm leaves and body mass,rather than intrinsic reproductive traits,were the main drivers of sperm production.Nevertheless,in both cases,the relationship between body mass,prey abundance,and food intake suggests that N.atrata follows the income breeding strategy to compensate for reproductive costs and to maximize fitness.

Covariation in Insular Life-history Traits of the Rice Frog(Fejervarya limnocharis)in Eastern China

Although shifts in life-history traits of insular vertebrates, as compared with mainland populations, have been observed in many taxa, few studies have examined the relationships among individual life-history traits on islands. Lifehistory theory also predicts that there is a trade-off between body size and reproductive effort, and between egg size and clutch size. We surveyed the rice frog, Fejervarya limnocharis, on 20 islands within the Zhoushan Archipelago and two nearby sites on the mainland of China to compare differences in life-history traits and to explore relationships among those traits. Rice frog females reached a greater body size on half of the smaller islands among the total 20 surveyed islands, and larger egg size, decreased clutch size and reduced reproductive effort on most of the islands when compared to the two mainland sites. Insular body size was negatively correlated with reproductive effort. There was a negative correlation between egg size and clutch size. Results suggest that life-history theory provides a good explanation for co-variation between body size and reproductive effort, and between egg size and clutch size in rice frogs on the islands.

Climate variation, reproductive frequency and acorn yield in English Oaks

Aims Annually variable but synchronous production of large seed crops(‘masting’)is a widespread phenomenon in temperate trees.Mounting concerns about the impacts of anthropogenic climate change(ACC)on plant reproduction gives urgency to our need to understand better the role of climate on tree reproduction,and in particular,mast events.Unlike our understanding of reproductive phenology however,there is little consensus regarding how climate affects plant reproductive effort or indeed the actual environmental triggers that underpin masting behaviour.Methods We used a 27-year record of acorn yield from a population of 12 Quercus robur trees located in southern England to compare mast-ing frequency and post-dispersal acorn yield each year for each tree,with long-term weather data over the same period.We focussed on discrete or sequential climate cues(temperature,precipitation and frost days)as likely predictors of oak reproduction.Important Findings Annual post-dispersal acorn crop varied greatly;i.e.no acorns in 14 of the 27 years,but there was no sequential pattern of crop ver-sus non-crop years indicating that weather,rather than resource limitation alone,dictated the timing of reproduction.Crop years were instead most closely associated with relatively cool late sum-mer conditions in the preceding year,followed by anomalous sum-mer warmth within crop year.Acorn yield increased following dry April and above-average May and June temperatures within crop year.Although our results support a general association between warm late spring and summer conditions,and crop frequency and yield,respectively,the influence of cooler later summer conditions in the year prior to masting highlights how a combination of weather cues may dictate the occurrence of mast years.Consequently,our results corroborate not only the hypothesis that temperature differ-entials between consecutive years,not absolute temperatures,may be the better predictor of mast seeding events but lend support also to the suggestion that reproductive failure and resource accumu-lation resulting from a climate-linked environmental veto,drives future reproductive synchronization in temperate tree species.