Reproductive Mode of Fejervarya limnocharis (Anura: Ranidae) Caught from Mae Sot, Thailand Based on Its Gonadosomatic Indices

Ovarian control and monitoring in amphibians

Amphibian evolution spans over 350 million years, consequently this taxonomic group displays a wide, complex array of physiological adaptations and their diverse modes of reproduction are a prime example. Reproduction can be affected by taxonomy, geographic and altitudinal distribution, and environmental factors. With some exceptions, amphibians can be categorized into discontinuous (strictly seasonal) and continuous breeders. Temperature and its close association with other proximate and genetic factors control reproduction via a tight relationship with circadian rhythms which drive genetic and hormonal responses to the environment. In recent times, the relationship of proximate factors and reproduction has directly or indirectly lead to the decline of this taxonomic group. Conservationists are tackling the rapid loss of species through a wide range of approaches including captive rescue. However, there is still much to be learned about the mechanisms of reproductive control and its requirements in order to fabricate species-appropriate captive environments that address a variety of reproductive strategies. As with other taxonomic groups, assisted reproductive technologies and other reproductive monitoring tools such as ultrasound, hormone analysis and body condition indices can assist conservationists in optimizing captive husbandry and breeding. In this review we discuss some of the mechanisms of ovarian control and the different tools being used to monitor female reproduction.

Digestive tract length is positively correlated with altitude across Fejervarya limnocharis populations

In animals, the amount of nutrients acquired through foraging and the proportion of metabolisable energy gained is reflected in the digestive tract length. This digestion theory predicts that the consumption of food with high content of indigestible material will lead to increased gut dimensions. Here, we analyzed geographic variation in digestive tract length related to diet among 14 Fejervarya limnocharis populations to test the digestion theory. Relative digestive tract length significantly differed between males and females and among populations. The relative length of the digestive tract increased with altitude. We also found a positive correlation between the proportion of plant material and digestive tract length for both sexes, which is consistent with the prediction of the digestion theory. Our findings suggest that variation in temperature associated with altitude affects food composition, and, thereby ultimately gut morphology of individuals.