This study estimated variability in components of reproductive success in female natterjack toads... more This study estimated variability in components of reproductive success in female natterjack toads (Bufo calamita, Laurenti, 1768) as a function of their body size and timing of reproduction. Two components of reproductive success were analysed: fecundity and metamorphic success. Fecundity, as a function of body size, tended to increase exponentially. Age had a negligible effect once body size was statistically controlled. Egg size was also related to female body size but showed greater variation. Metamorphic success depended on the timing of reproduction. Later breeders suffered an exponential decline in metamorphic success because females spawned at recently-filled ponds of ephemeral duration. Since female body size decreased as the breeding season progressed, it may be inferred that larger, early-breeding females would have a differential reproductive success. The inverse relationship between the timing of reproduction and body size may be based on the energetic physiology of vitellogenesis, and on the potential trade-offs between the allocation of energy to growth—higher in smaller females—and reproduction.
I studied size-dependent vulnerability and behavioral responses of tadpoles to pre- daceous divin... more I studied size-dependent vulnerability and behavioral responses of tadpoles to pre- daceous diving beetle larvae (Dytiscus pisanus) in two anuran species (Bufo calamita and Pelobates cultripes) that breed in temporary ponds. Experiments revealed that large tadpoles of B. calamita were preferentially selected by the beetle larvae. Moreover, the average number of strikes to grasp a small tadpole was higher than for large tadpoles. However, in P. cultripes, large tadpoles were less likely to be captured than were small tadpoles. Both species differed in growth history; B. calamita has a short growth period and a small tadpole that is unable to avoid predation, whereas P. cultripes grows to a large size that reduces predation rate. Tadpoles of B. calamita show a reduction in mobility in the presence of the predator, whereas tadpoles of P. cultripes do not show it. Phylogenetic constraints restricting size at metamorphosis for B. calamita may lead to the adoption of alternative antipredatory strategies, such as a reduction in activity or habitat segregation.
Male and female natterjack toads, Bufo calamita, exhibited a high degree of breeding synchronizat... more Male and female natterjack toads, Bufo calamita, exhibited a high degree of breeding synchronization. A polynomial or exponential regression indicated that the operational sex ratio (OSR) between nights increased with number of males in the overall population; hence, OSR varied temporally with chorus size. The comparison of three different groups of calling males within the breeding area, separated from each other and differing in male numbers, revealed similar OSRs between groups. Therefore, OSR did not vary spatially with chorus size. On average, males that attended larger groups obtained higher mating success in one season but not in another. Male movements between groups were directed toward larger groups, with higher OSRs and higher number of calling males, but males did not increase their mating probabilities by moving to another group. Female distribution among groups was correlated with the availability of oviposition sites, but they were not attracted differentially to large male groups or to groups with more callers.
... Different ecological conditions in the Spanish population, with a more explosive breeding sea... more ... Different ecological conditions in the Spanish population, with a more explosive breeding season, may explain the different relationship between male body size and ... Energetic Constraints Hypothesis Chorus attendance was the best predictor of male mating success in ...
... This last protective property has been con-sidered dynamic, decreasing during de-velopment (B... more ... This last protective property has been con-sidered dynamic, decreasing during de-velopment (Brodie et al., 1978). Bufo calamita (the natterjack toad) breeds in temporary ponds. Its clutches are preyed upon by adults of Triturus boscai and T. marmoratus (Diaz-Paniagua, per ...
The climate variability hypothesis posits that increased environmental thermal variation should s... more The climate variability hypothesis posits that increased environmental thermal variation should select for thermal generalists, while stable environments should favor thermal specialists. This hypothesis has been tested on large spatial scales, such as latitude and elevation, but less so on smaller scales reflective of the experienced microclimate. Here, we estimated thermal tolerance limits of 75 species of amphibian tadpoles from an aseasonal tropical mountain range of the Ecuadorian Andes, distributed along a 3500 m elevational range, to test the climatic variability hypothesis at a large (elevation) and a small (microhabitat) scale. We show how species from less variable thermal habitats, such as lowlands and those restricted to streams, exhibit narrower thermal tolerance breadths than highland and pond‐dwelling species respectively. Interestingly, while broader thermal tolerance breadths at large scales are driven by higher cold tolerance variation (heat‐invariant hypothesis), ...
This study estimated variability in components of reproductive success in female natterjack toads... more This study estimated variability in components of reproductive success in female natterjack toads (Bufo calamita, Laurenti, 1768) as a function of their body size and timing of reproduction. Two components of reproductive success were analysed: fecundity and metamorphic success. Fecundity, as a function of body size, tended to increase exponentially. Age had a negligible effect once body size was statistically controlled. Egg size was also related to female body size but showed greater variation. Metamorphic success depended on the timing of reproduction. Later breeders suffered an exponential decline in metamorphic success because females spawned at recently-filled ponds of ephemeral duration. Since female body size decreased as the breeding season progressed, it may be inferred that larger, early-breeding females would have a differential reproductive success. The inverse relationship between the timing of reproduction and body size may be based on the energetic physiology of vitellogenesis, and on the potential trade-offs between the allocation of energy to growth—higher in smaller females—and reproduction.
I studied size-dependent vulnerability and behavioral responses of tadpoles to pre- daceous divin... more I studied size-dependent vulnerability and behavioral responses of tadpoles to pre- daceous diving beetle larvae (Dytiscus pisanus) in two anuran species (Bufo calamita and Pelobates cultripes) that breed in temporary ponds. Experiments revealed that large tadpoles of B. calamita were preferentially selected by the beetle larvae. Moreover, the average number of strikes to grasp a small tadpole was higher than for large tadpoles. However, in P. cultripes, large tadpoles were less likely to be captured than were small tadpoles. Both species differed in growth history; B. calamita has a short growth period and a small tadpole that is unable to avoid predation, whereas P. cultripes grows to a large size that reduces predation rate. Tadpoles of B. calamita show a reduction in mobility in the presence of the predator, whereas tadpoles of P. cultripes do not show it. Phylogenetic constraints restricting size at metamorphosis for B. calamita may lead to the adoption of alternative antipredatory strategies, such as a reduction in activity or habitat segregation.
Male and female natterjack toads, Bufo calamita, exhibited a high degree of breeding synchronizat... more Male and female natterjack toads, Bufo calamita, exhibited a high degree of breeding synchronization. A polynomial or exponential regression indicated that the operational sex ratio (OSR) between nights increased with number of males in the overall population; hence, OSR varied temporally with chorus size. The comparison of three different groups of calling males within the breeding area, separated from each other and differing in male numbers, revealed similar OSRs between groups. Therefore, OSR did not vary spatially with chorus size. On average, males that attended larger groups obtained higher mating success in one season but not in another. Male movements between groups were directed toward larger groups, with higher OSRs and higher number of calling males, but males did not increase their mating probabilities by moving to another group. Female distribution among groups was correlated with the availability of oviposition sites, but they were not attracted differentially to large male groups or to groups with more callers.
... Different ecological conditions in the Spanish population, with a more explosive breeding sea... more ... Different ecological conditions in the Spanish population, with a more explosive breeding season, may explain the different relationship between male body size and ... Energetic Constraints Hypothesis Chorus attendance was the best predictor of male mating success in ...
... This last protective property has been con-sidered dynamic, decreasing during de-velopment (B... more ... This last protective property has been con-sidered dynamic, decreasing during de-velopment (Brodie et al., 1978). Bufo calamita (the natterjack toad) breeds in temporary ponds. Its clutches are preyed upon by adults of Triturus boscai and T. marmoratus (Diaz-Paniagua, per ...
The climate variability hypothesis posits that increased environmental thermal variation should s... more The climate variability hypothesis posits that increased environmental thermal variation should select for thermal generalists, while stable environments should favor thermal specialists. This hypothesis has been tested on large spatial scales, such as latitude and elevation, but less so on smaller scales reflective of the experienced microclimate. Here, we estimated thermal tolerance limits of 75 species of amphibian tadpoles from an aseasonal tropical mountain range of the Ecuadorian Andes, distributed along a 3500 m elevational range, to test the climatic variability hypothesis at a large (elevation) and a small (microhabitat) scale. We show how species from less variable thermal habitats, such as lowlands and those restricted to streams, exhibit narrower thermal tolerance breadths than highland and pond‐dwelling species respectively. Interestingly, while broader thermal tolerance breadths at large scales are driven by higher cold tolerance variation (heat‐invariant hypothesis), ...
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Papers by Miguel Tejedo