Factors influencing offspring traits in the oviparous multi-clutched lizard,Calotes versicolor (Agamidae)

The determinants of offspring size and number in the tropical oviparous multi-clutched lizard, Calotes versicolor, were examined using both univariate and multivariate (path) analyses. In C. versicolor maternal snout-vent length (SVL) and body condition influence clutch mass and clutch size but have no significant influence on offspring size. The positive effect of maternal SVL and body condition on offspring number is counterbalanced by a negative effect of breeding time on egg mass. In fact, breeding time directly influences the offspring body mass and condition through variation in the egg mass. There is a trade-off between offspring mass and condition with offspring number, and breeding time influences both. Offspring hatched from the eggs of early (May-June) or mid (July-August) breeding periods invariably show lower mass and condition than those hatched from the eggs of late breeding season (September-October). Yet, there is no variation in offspring SVL among early, mid and late clutches. Thus, inC. versicolor offspring SVL is optimized while body mass and condition are not optimized

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

Relative susceptibility of tadpoles of Uperodon taprobanicus (Anura: Microhylidae) and Duttaphrynus melanostictus (Anura: Bufonidae) to predacious Hoplobatrachus tigerinus (Anura: Dicroglossidae) tadpoles: significance of refugia and swimming speed in pre

The relative susceptibility of two closely associated herbivorous tadpole species (Uperodon taprobanicus and Duttaphrynus melanostictus) to their natural carnivorous predatory tadpole, Hoplobatrachus tigerinus and the significance of refugia in predator avoidance was studied in the laboratory. In a total of 50 trials, 10 tadpoles each of U. taprobanicus and D. melanostictus of comparable sizes were exposed to starved H. tigerinus. Twenty-five trials included refugia while 25 did not. The results of this study showed that in both the presence and absence of refugia, D. melanostictus tadpoles fell prey to H. tigerinus more frequently than U. taprobanicus tadpoles. A key difference between the two prey species is the speed of swimming; Vmax of D. melanostictus (13.58 cm/s) tadpoles is significantly lower than that of U. taprobanicus (24.89 cm/s) tadpoles. This is likely to be the main reason why more D. melanostictus tadpoles were preyed upon than were U. taprobanicus tadpoles. It is important to note that the Vmax of the predator (60.21 cm/s) is much greater than those of the two prey species. However, predation risk of both prey tadpole species was affected significantly by the presence of refugia. The susceptibility of both prey tadpole species was lower where refugia were available. The present study clearly demonstrates that the more efficient avoidance of predation by U. taprobanicus tadpoles could be due to better use of refugia and their faster rate of movement.A suscetibilidade relativa de duas espécies de girinos herbívoros intimamente associados (Uperodon taprobanicus e Duttaphrynus melanostictus) ao seu girino predador carnívoro natural, Hoplobatrachus tigerinus, e a importância do refúgio na fuga do predador foram estudadas em laboratório. Em um total de 50 testes, 10 girinos de U. taprobanicus e 10 girinos de D. melanostictus de tamanhos comparáveis foram expostos a girinos de H. tigerinus famintos. Vinte e cinco testes incluíram refúgios, enquanto 25 não incluíram. Os resultados desse estudo mostraram que, tanto na presença como na ausência de refúgios, os girinos de D. melanostictus foram predados com mais frequência do que os girinos de U. taprobanicus. Uma diferença importante entre as duas espécies de presas é a velocidade de natação; a Vmax dos girinos de D. melanostictus (13,58 cm/s) é significativamente menor do que a dos girinos de U. taprobanicus (24,89 cm/s). É provável que esse seja o principal motivo pelo qual mais girinos de D. melanostictus foram predados em relação aos girinos de U. taprobanicus. É importante observar que a Vmax do predador (60,21 cm/s), é muito maior do que a das duas espécies de presas. No entanto, o risco de predação de ambas as espécies degirinos foi afetado significativamente pela presença de refúgios. A suscetibilidade de ambas as espécies de girinos foi menor quando havia refúgios disponíveis. O presente estudo demonstra claramente que a evasão mais eficiente da predação pelos girinos de U. taprobanicus pode ser devida ao melhor uso dos refúgios e à sua taxa de movimento mais rápida

Factors influencing offspring traits in oviparous multi-cluthced lizard, Calotes versicolor (Agamidae

The determinants of offspring size and number in the tropical oviparous multi-clutched lizard, Calotes versicolor, were examined using both univariate and multivariate (path) analyses. In C. versicolor maternal snout-vent length (SVL) and body condition influence clutch mass and clutch size but have no significant influence on offspring size. The positive effect of maternal SVL and body condition on offspring number is counterbalanced by a negative effect of breeding time on egg mass. In fact, breeding time directly influences the offspring body mass and condition through variation in the egg mass. There is a trade-off between offspring mass and condition with offspring number, and breeding time influences both. Offspring hatched from the eggs of early (May-June) or mid (JulyAugust) breeding periods invariably show lower mass and condition than those hatched from the eggs of late breeding season (September-October). Yet, there is no variation in offspring SVL among early, mid and late clutches. Thus, in C. versicolor offspring SVL is optimized while body mass and condition are not optimized

Behavioral responses of tadpoles of Clinotarsus curtipes (Anura: Ranidae) to odor cues of dragonfly larvae

Em ambientes aquáticos, muitas presas, inclusive larvas de anuros, usam predominantemente sinais químicos para avaliar o risco de predação. Nesses sistemas, uma variedade de sinais químicos (por exemplo, cairomônios, alarme, dieta) afeta as respostas comportamentais dos girinos. Muitos girinos são capazes de discriminar diferentes sinais químicos e apresentar respostas comportamentais diferenciadas contra predadores de acordo com o risco percebido. As respostas comportamentais dos girinos de Clinotarsus curtipes às larvas predadoras da libélula Pantala flavescens foram estudadas em laboratório. Os cairomônios do predador (água condicionada por um predador faminto) ou seus metabólitos derivados da dieta liberados nas excretas de um predador após o consumo de girinos conspecíficos (C. curtipes) ou heterogenéricos (Indosylvirana temporalis) foram usados para simular o risco de predação. Os girinos de C. curtipes não apresentaram resposta comportamental aos cairomônios do predador. No entanto, os girinos apresentaram respostas comportamentais anti-predador, ou seja, redução dos movimentos de natação e do tempo total gasto nadando, e maior velocidade de explosão em resposta a sinais transportados pela água e liberados nas excretas de predadores alimentados com presas conspecíficas e heterogenéricas. As respostas comportamentais antipredador dos girinos foram mais intensas em resposta a sinais de predadores alimentados com presas específicas. Os resultados do presente estudo mostram que os girinos de C. curtipes são capazes de avaliar os níveis de ameaça de predação e modular a intensidade de seu comportamento de defesa de acordo com a risco percebido.In aquatic environments, many prey animals, including anuran larvae, predominantly use chemical cues to assess predation risk. In such systems, a variety of chemical cues (e.g., kairomones, alarm, dietary) affect the behavioral responses of the prey tadpoles. Many anuran tadpoles are able to discriminate different chemical cues and exhibit differential antipredator behavioral responses according to the perceived risk. The behavioral responses of tadpoles of Clinotarsus curtipes to predatory larvae of the dragonfly Pantala flavescens were studied in the laboratory. The predator’s kairomones (water conditioned by a starved predator) or its diet-derived metabolites released in excreta of a predator after consumption of conspecific (C. curtipes) or heterogeneric (Indosylvirana temporalis) prey tadpoles were used to simulate predation threat. The tadpoles of C. curtipes had no behavioral response to predator kairomones. However, the tadpoles showed antipredator behavioral responses i.e., reduced swimming movements and overall time spent swimming, and had a higher burst speed in response to water-borne cues released from the excreta of predators fed both conspecific and heterogeneric prey. The antipredator behavioral responses of tadpoles were most intense in response to cues of predators fed on conspecific prey. The findings of the present study show that tadpoles of C. curtipes are capable of assessing levels of predation threat and modulating the intensity of their defense behavior in accordance with the perceived threat

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 ≅ 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

Adaptive plasticity in anuran metamorphosis: response of tadpoles of Polypedates maculatus (Anura: Rhacophoridae) to pond drying

The influence of desiccation on metamorphic traits (larval duration and size at emergence) was studied in Polypedates maculatus under laboratory conditions. Gosner Stage 23 tadpoles were exposed to decreasing water levels (gradual or rapid) until the beginning of metamorphic climax (Stage 42). A control group was reared in constant water levels. Tadpoles reared in decreasing water levels reached the metamorphic climax earlier and metamorphosed at a smaller size than those reared in constant water levels. Further, tadpoles experiencing rapid depletion of water reached the metamorphic climax earlier and metamorphosed at a smaller size than those experiencing gradual depletion of water levels. Tadpoles of P. maculatus showed adaptive plasticity in metamorphosis to pond drying. Survival of tadpoles in treatments and the control was 100%. The study revealed that tadpoles of P. maculatus have plastic development in response to water levels; the trade-off between growth and development favors development, which results in early metamorphosis at a small size.A influência do dessecamento nas características metamórficas (duração do estágio larval e tamanho na emergência) foi estudada em Polypedates maculatus sob condições de laboratório. Girinos no Estágio 23 de Gosner foram expostos a níveis de água decrescentes (graduais ou rápidos) até o início do clímax metamórfico (Estágio 42). Um grupo-controle foi criado em níveis de água constantes. Os girinos criados em níveis de água decrescentes atingiram o clímax metamórfico mais cedo e se metamorfosearam em um tamanho menor do que aqueles criados em níveis de água constantes. Além disso, os girinos que sofreram um rápido esgotamento da água atingiram o clímax metamórfico mais cedo e se metamorfosearam em um tamanho menor do que aqueles que sofreram um esgotamento gradual dos níveis de água. Os girinos de P. maculatus mostraram plasticidade adaptativa na metamorfose em relação ao dessecamento do tanque. A sobrevivência dos girinos nos tratamentos e no grupo-controle foi de 100%. O estudo revelou que os girinos de P. maculatus têm um desenvolvimento plástico em resposta aos níveis d’água; a compensação entre crescimento e desenvolvimento favorece o desenvolvimento, o que resulta em metamorfose precoce em um tamanho pequeno

Perch Associated Expression of Phenotypic Plasticity in Limb Development and Sprint Speed in Agamid Lizard Calotes versicolor: A Laboratory Study

New born hatchlings of Calotes versicolor were reared in terrarium having narrow or wide perches for a period of 4-month and their snout vent length (SVL), tail, fore and hindlimb lengths were measured at monthly intervals. Limb postures (closer to the body or spread away from the body) were also recorded. The sprint speed was recorded in two and four-month old lizards on a 1 m long race track providing 45° or 60° slope. In both the groups, SVL and tail lengths were comparable but the limb lengths and their growth rates were significantly greater in lizards of wider perch group. The lizards reared with narrow perches positioned their limbs closer to the body; while those reared on wider perches spread their limbs away from their body. Further, the latter exhibited significantly higher sprint speed regardless of the slope of the race track over those of narrow perch group. Sprint speeds of lizards in both groups were correlated with the limb sizes. The study showed that the lizards reared on narrow or wide perches exhibited divergent adaptive responses (phenotypic plasticity) by developing longer or shorter limbs and corresponding changes in their sprint speeds. These findings support the idea that availability of perch structure during early development evokes adaptive plasticity in the limb development and associated locomotory performance in arboreal lizards like C. versicolor

Respostas comportamentais de girinos de Polypedates maculatus (Anura: Rhacophoridae) criados em laboratório e capturados na natureza a sinais alimentares dos girinos carnívoros de Hoplobatrachus tigerinus (Anura: Dicroglossidae)

As respostas comportamentais de girinos de Polypedates maculatus criados em laboratório e capturados na natureza aos girinos predadores de Hoplobatrachus tigerinus foram estudadas em laboratório. Os metabólitos derivados da dieta do predador liberados na excreta do predador após o consumo de girinos de P. maculatus foram usados para simular a ameaça de predação. Tanto os girinos de P. maculatus criados em laboratório como os capturados na natureza apresentaram respostas comportamentais contra predadores, ou seja, reduziram os movimentos de natação e o tempo total gasto na natação e tiveram uma velocidade de explosão mais alta em resposta a sinais alimentares de predadores na água. Além disso, as respostas anti-predação dos girinos capturados na natureza foram significativamente maiores do que as exibidas pelos girinos criados em laboratório. O estudo mostra, portanto, que o comportamento anti-predação desses girinos é inato. Além disso, um comportamento anti-predação aprimorado dos girinos capturados na natureza pode sugerir sua experiência anterior com predadores em águas naturais.The behavioral responses of laboratory-reared and wild-caught tadpoles of Polypedates maculatus to predatory tadpoles of Hoplobatrachus tigerinus were studied in the laboratory. The predator’s diet-derived metabolites released in excreta of predator after consumption of P. maculatus tadpoles were used to simulate predation threat. Both laboratory-reared and wild-caught tadpoles of P. maculatus showed antipredator behavioral responses i.e., reduced swimming movements and overall time spent in swimming and had a higher burst speed in response to water borne dietary cues of predators. Further, the antipredator responses of wild-caught tadpoles were significantly higher than those exhibited by laboratory-reared tadpoles. The studythus shows that antipredator behavior in these tadpoles is innate. Further, an enhanced antipredator behavior of wild-caught tadpoles may suggest their prior experience with predators in natural waters

Expressão da plasticidade fenotípica em filhotes do lagarto Calotes versicolor (Squamata: Agamidae): influência da umidade do ninho.

Calotes versicolor se reproduz do final de maio ao início de outubro. A atividade de reprodução começa logo após a monção sul-oeste. Os ovos depositados no início da estação reprodutiva experimentam condições mais úmidas do que aqueles do final da estação. Nós estudamos a influência do nível de umidade do ninho sobre as características fenotípicas dos filhotes recém-eclodidos enterrando os ovos em ninhos de areia de 5 cm de profundidade com ~50% (ninho úmido) ou ~20% (ninho relativamente seco) de umidade para simularas condições de nidificação do início e do final da estação reprodutiva. Um grupo de ovos foi submetido a um  procedimento padronizado de incubação laboratorial em que os ovos são semienterrados na areia úmida enquanto a outra metade permanece exposta ao ar. O tempo de eclosão eo tamanho corporal dos filhotes recém-eclodidos variaram com o tratamento. Os ovos dos ninhos secos eclodiram mais tarde e os filhotes foram os maiores, mas possuíam menor quantidade de vitelo residual comparados com os grupos de ''ninhos úmidos'' e também de ''incubação laboratorial''.Nesses filhotes, os tamanhos da cabeça e dos membros foram significativamente maiores do que os dos outros dois grupos. Os resultados mostram: (1) uma plasticidade de desenvolvimento no lagarto, (2) que sob condições de baixa umidade um tamanho corporal maior é preferível e (3) que ocompromisso entre o crescimento somático dos embriões e as reservas energéticas futuras (vitelo residual) dos filhotes é influenciado pela umidade do solo em C. versicolor.Calotes versicolor breed from late May to early October. The breeding activity begins with the onset of the southwestmonsoon. The eggs laid in early breeding season experience more wet conditions than those of the late breeding season. We studied the influence of nest moisture levels on thephenotypic traits of hatchlings by burying the eggs in 5-cm-deep sand nests with ~50% (wet nest) or ~20% (relatively dry nest) moisture to simulate nesting conditions of early and late breeding seasons. A group of eggs were subjected to standard laboratory incubation procedure in which eggs are half-buried in the moist sand and the other half exposed to air. Hatching time and hatchling body size varied with the treatment. The eggs from dry nests hatched later and hatchlings were the biggest but possessed least amount of residual yolk compared to those of ''wet nest'' and also ''lab incubated'' groups. In these hatchlings head and limb sizes were significantly larger than that of the other two groups. The findings show: (1) a developmental plasticity in the lizard, (2) that under low moist conditions larger body size is preferred, and (3) that the trade-off between somatic growth of embryosand future energy reserves (residual yolk) of hatchlings is influenced by the soil moisture in C. versicolor