• Srinivas K Saidapur

      Articles written in Journal of Biosciences

    • Foraging behaviour in tadpoles of the bronze frogRana temporalis: Experimental evidence for the ideal free distribution

      Dheeraj K Veeranagoudar Bhagyashri A Shanbhag Srinivas K Saidapur

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      The ability of bronze frogRana 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 equationSi =Bifi (di) whereBi 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, anddi is the density of tadpoles in habitati. 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 ofR. temporalis tadpoles matched ideally with habitat profitability (undermatching indexK ≜ 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.

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

      Lilly Margaret Eluvathingal Bhagyashri A Shanbhag Srinivas K Saidapur

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      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.

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