Absence of kin discrimination in cannibalistic Anuran tadpoles of the frog Hoplobatrachus tigerinus (Daudin).

Kin discrimination was tested in the cannibalistic H. tigerinus tadpoles to know whether cannibalism is selectively directed towards non-kin members or it is indiscriminate. The association choice tests were conducted using satiated as well as starved subjects with the assumption that they will associate near non-sibs rather than near sibs with the intention of preferentially cannibalizing them. However, test tadpoles, fed or starved showed a random association choice with sibs and non-sibs, as in the end-bias stimulus blank tests. Therefore it is suggested that cannibalistic H. tigerinus tadpoles do not discriminate sibs from non-sibs and cannibalize on both rather indiscriminately.

Association preference and mechanism of kin recognition in tadpoles of the toad Bufo melanostictus.

In experiments with specially designed choice tanks, tadpoles of Bufo melanostictus spend significantly greater amounts of time near kin than near non-kin. However, in the absence of kin members, they prefer to spend more time near non-kin rather than stay away in isolation in the opposite blank zone with no company. This implies that association of toad tadpoles with their kin is due to attraction rather than repulsion from non-kin. Experiments designed to elucidate the sensory basis of kin recognition showed that toad tadpoles recognize their kin based on chemical cues rather than visual cues. They can also discriminate between homospecific non-kin and heterospecific (Sphaerotheca breviceps) tadpoles since the tadpoles spent significantly greater amounts of time near the former than near the latter. These findings suggest that where kin members are unavailable, selection may have favoured living with non-kin so as to derive benefits from group living and that a phenotype-matching mechanism may operate for both kin and species discrimination in B. melanostictus.

Taxonomic relationships within the pan-oriental narrow-mouth toad Microhyla ornata as revealed by mtDNA analysis (Amphibia, Anura, Microhylidae).

A molecular phylogenetic survey was conducted using mtDNA sequences of 12S and 16S rRNA, and cyt-b genes to examine taxonomic relationships among populations of the Pan-Oriental microhylid, Microhyla ornata, from India, Bangladesh, Thailand, Laos, China, Taiwan, and the Ryukyu Archipelago of Japan. Two discrete clades are recognized within this species, one consisting of populations from India and Bangladesh, and the other encompassing the remaining populations. In the latter clade, populations from the Ryukyu Archipelago are clearly split from the rest (populations from Taiwan and the continent) with considerable degrees of genetic differentiations. Each of the three lineages is judged to represent a good species, and the name Microhyla ornata is restricted to the South Asian populations. For the populations from Taiwan and a wide region from China to Southeast Asia, the name Microhyla fissipes should be applied, whereas the Ryukyu populations are most appropriately referred to as Microhyla okinavensis, although further substantial genetic differentiations are recognized among some island group populations within this last species.

Yolk partitioning in embryos of the lizard, Calotes versicolor: maximize body size or save energy for later use?

The hatchlings of Calotes versicolor and other congeners retain residual yolk for immediate post-hatching needs. Excision of 8% yolk (approximately equal residual yolk) from the eggs resulted in smaller hatchlings when compared to those emerging from sham operated eggs. However, hatchlings in both groups retained the same amount of residual yolk. The findings suggest that residual yolk in hatchlings of C. versicolor is an important part of the energy budget set aside by developing embryos and that the advantages of large hatchling size are counter balanced by selection for residual yolk.

Foraging behaviour in tadpoles of the bronze frog Rana temporalis: experimental evidence for the ideal free distribution.

The ability of bronze frog Rana temporalis tadpoles (pure or mixed parental lines) to assess the profitability of food habitats and distribute themselves accordingly was tested experimentally using a rectangular choice tank with a non- continuous input design. Food (boiled spinach) was placed at two opposite ends of the choice tank in a desired ratio (1 : 1, 1 : 2 or 1 : 4) to create habitat A and B. The tadpoles in Gosner stage 28-33, pre-starved for 24 h, were introduced in an open ended mesh cylinder placed in the center of the choice tank, held for 4 min (for acclimation) and then released to allow free movement and habitat selection. The number of tadpoles foraging at each habitat was recorded at 10, 15, 20, 25 and 30 min time intervals. The actual suitability, Si (the food available in a habitat after colonization of tadpoles) of each habitat was obtained from the equation Si = Bi - fi (di) where Bi is basic suitability (amount of food provided at each habitat before release of tadpoles), fi is the rate of depletion of food (lowering effect) with introduction of each tadpole, and di is the density of tadpoles in habitat i. The expected number of tadpoles at each habitat was derived from the actual suitability. With no food in the choice tank, movement of the tadpoles in the test arena was random indicating no bias towards any end of the choice tank or the procedure. In tests with a 1 : 1 food ratio, the observed ratio of tadpoles (11.71 : 12.28) was comparable with the expected 12 : 12 ratio. The observed number of tadpoles in the habitats with a 1 : 2 food ratio was 8.71 : 15.29 and 7.87 : 16.13 for pure and mixed parental lines respectively. In both cases, the observed ratios were close to the expected values (7 : 17). Likewise, in experiments with a 1 : 4 food ratio, the observed number of tadpoles in the two habitats (10.78 : 37.22) did not differ significantly from the expected ratio of 7 : 41. In all tests, the number of R. temporalis tadpoles matched ideally with habitat profitability (undermatching index K approximate, equals 1). The study shows that tadpoles of the bronze frog exhibit an ideal free distribution while foraging regardless of whether they are siblings or non-siblings in a group, which correlates well with their group living strategy in nature

Lowering body temperature induces embryonic diapause during prolonged egg retention in the lizard, Calotes versicolor.

The lizard Calotes versicolor delays oviposition of oviductal eggs for as long as 6 months or more under unfavourable conditions. During this period of prolonged egg retention, the growth of oviductal embryos is arrested at stage 34. The present study shows for the first time among reptiles that the "embryonic diapause" is manifested by the gravid females by lowering their body temperature ( T(b)) by 3-5 degrees C during the period of egg retention by mechanism(s) presently unknown.