Sexual signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition. Thus, chemical secretions of lizards might evolve in the evolutionary time to ensure that signals are perfectly tuned to local humidity and temperature conditions affecting their volatility and therefore their persistence and transmission through the environment. We tested experimentally whether interpopulational altitudinal differences in chemical composition of femoral gland secretions of male Iberian wall lizards (Podarcis hispanicus) have evolved to maximize efficacy of chemical signals in different environmental conditions. Chemical analyses first showed that the characteristics of chemical signals of male lizards differed between two populations inhabiting environments with different climatic conditions in spite of the fact that these two populations are closely related genetically. We also examined experimentally whether the temporal attenuation of the chemical stimuli depended on simulated climatic conditions. Thus, we used tongue-flick essays to test whether female lizards were able to detect male scent marks maintained under different conditions of temperature and humidity by chemosensory cues alone. Chemosensory tests showed that chemical signals of males had a lower efficacy (i.e. detectability and persistence) when temperature and dryness increase, but that these effects were more detrimental for signals of the highest elevation population, which occupies naturally colder and more humid environments. We suggest that the abiotic environment may cause a selective pressure on the form and expression of sexual chemical signals. Therefore, interpopulational differences in chemical profiles of femoral secretions of male P. hispanicus lizards may reflect adaptation to maximize the efficacy of the chemical signal in different climates.

Predation has profound effects on the phenotypes of animal prey and, in lizards, the relationship between coloration and antipredatory behaviour has been studied in depth. However, studies that address the relationships between dorsal patterns and tail coloration with escape behaviour in polymorphic lizards are absent in the literature. We describe dorsal morphs and measured tail coloration and escape behaviour in hatchling Iberian wall lizards, Podarcis hispanicus, a species with a previously undescribed female-restricted dorsal polymorphism (reticulated-blotched males, and either striped or reticulated-blotched females) and juvenile tails with conspicuous blue coloration, which is probably used to divert predator attacks towards the autotomizable tail. Overall we provide evidence for the existence of sexual dimorphism in tail ultraviolet reflectance between reticulated females and males, with striped females being intermediate. We identified sex/dorsal morph, body size and tail brightness as predictors of different aspects of escape behaviour and suggest the existence of two alternative escape strategies between striped and reticulated-blotched females that may be dependent on dorsal morph differences, independently of sex. Reticulated-blotched females, and also males (all reticulated-blotched), ran faster and spent less time paused than striped females, which might reflect an escape behaviour strategy based on endurance in striped females. In addition, lowland males displayed tail waving as a 'last resort' antipredator strategy that may be related to fatigue. We concluded that hatchling antipredatory behaviour is influenced by both dorsal pattern and tail conspicuousness.

Between 4 and 16 January 1996, during a period of cool weather, we studied the emergence and foraging behavior of Molossus ater at a site near Akumal, in the Yucatan Peninsula in Mexico. The bats, a colony of at least 32 individuals, roosted in a north‐facing cinder block wall, and emerged about sunset. Emerging bats were usually clustered in time, while those returning usually were not. Radio‐tracking revealed that the bats foraged for short periods (mean 26.8 min) and captures of returning individuals indicated that 27 of 28 had fed, taking, on average, 4.4 g of insects, mainly hydrophilid beetles. On some nights, few or none of the radio‐tagged bats emerged from the roost. Calculations concerning the costs of flight and roosting show that they were more than covered by the energy intake the bats achieved. Molossus ater have high aspect ratio (8.3–9.1) wings and high wing‐loadings of 17.55–24.15 N/m2. When searching for prey, these bats produce long (12.3 ms), narrowband(3.8 kHz), echolocation calls that sweep from 27.6–23.8 kHz. Energy was not limiting for these bats at the time of our study.

Morphological adaptations of amphisbaenians for a fossorial life constrain their ecological demands in a greater way than for epigeal reptiles. Studies on the diet of amphisbaenians suggest that most species are generalists, although others seem more selective. However, there is no information on the diet preferences of almost any species because most studies did not evaluate the availability of prey in the environment. We analysed the spring diet selection of a population of the amphisbaenian Trogonophis wiegmanni from the Chafarinas Islands, in North Africa. We specifically examined diet estimated from faecal material collected from live amphisbaenians and compared diet with the availability of invertebrates in the soil. Results indicate that the diet of T. wiegmanni amphisbaenians consists of some of the types of invertebrates that are more commonly found under rocks used by amphisbaenians, such as insect larvae, snails, isopods, beetles and ants. This diet could be initially considered generalist, and probably opportunistic. However, the comparison of proportions of prey types in the diet and those available in the habitat revealed that T. wiegmanni does not eat prey at random, but selects some particular prey types (insect larvae and pupae and, surprisingly, snails), while others (ants and isopods) are consumed less than expected by their abundance. We did not found differences between sexes or age classes in diet composition. We discuss how diet preferences could be due to selection of the more profitable or easily captured prey. There are many aspects of the feeding and foraging biology of amphisbaenians that remain unknown and further studies are clearly needed.

The interplay between ecological conditions and life histories has been widely acknowledged in vertebrates, particularly in lizards. Environmental conditions may exert different selective pressures and produce divergent phenotypes even in geographically and genetically close populations. The Iberian wall lizard, constitutes a perfect model organism as it is considered a species complex with a complicated evolutionary history. Here, we focus on two nearby populations in which we examined adult morphology and reproductive investment of wild caught lizards along a 500 m altitudinal gradient with contrasting environmental conditions, where adults show marked morphological differences in spite of being closely related. Also we performed a common garden experiment to examine embryonic and hatchling growth. We focused on reproductive investment per clutch, incubation time, egg size, morphology and growth rate of hatchlings. Results showed clutch size differences between populations that were independent of the larger body size of highland females. However, there were not egg morphological differences between populations, except for egg width, and this difference disappeared after controlling for female body size. Hatchling lizards from both populations did not differ in morphology. Moreover, we did not observe differences between populations nor sexes in hatchling growth. Overall, we provide evidence that the differences in adult body size and clutch size are not driven by size at hatching which is not contributed to by egg size, nor intrinsic hatchling growth rates associated with the environmental conditions experienced in our common garden experiment, suggesting that adult phenotypes are not the result of intrinsic differences between populations.

Limbless animals that burrow head‐first are often considered to be evolutionarily constrained in the development of a large head, due to limitations imposed while penetrating the soil. Whilst animals with a small head experience less resistance when digging, they are believed to have a weak bite, hence restricting their potential dietary spectrum to soft prey. Yet, recent findings established molluscivory in the fossorial worm lizard Trogonophis wiegmanni (Amphisbaenia), suggesting a high bite capacity for this burrowing species necessary to crush snail shells. To tackle this burrow/crush dilemma, we examined the relationship between head morphology, bite force and gastropod diet in T. wiegmanni males and females. In vivo bite force analyses and shell hardness measurements were used to assess the potential dietary spectrum of the amphisbaenians. In addition, phylogenetic analyses were performed to put T. wiegmanni's head size and bite force into an interspecific comparative context. Our results show a strong positive relation between head size and bite force, and we found no evidence for sexual dimorphism. In sharp contrast to other durophagous lizards, T. wiegmanni combines a relatively small body and a (disproportionally) small head with relatively high biting forces. In fact, T. wiegmanni is able to crush a wide array of the most abundant gastropod shells in their environment. However, the head size of the strongest biters imposes a limitation towards a common alternative snail‐feeding strategy: entering the opening of the gastropod shell. This study shows that head size, and consequently bite force, increases the number and variety of gastropods that can be consumed by ‘shell‐crushing’, but reduces the number and variety of snails that can be consumed by ‘shell‐entering’, and vice versa. The cranial design of (durophagous) limbless burrowers may therefore not only evolve under constraints for efficient soil penetration, but also through selection for diet.

Sex-specific colour polymorphisms have been extensively documented in many different taxa. When polymorphism in colour pattern is restricted to females, the condition is known as female-limited pattern polymorphism (FPP), which has been less commonly addressed in vertebrates. FPP is present in several lizard species, although most research on lizards has focused on carotenoid-and pteridine-based coloration and not on melanin-based polymorphisms. In the present study, we focus on Iberian wall lizards, Podarcis hispanicus, where two female melanin-based dorsal patterns can be clearly distinguished: striped and reticulated-blotched. We indirectly tested the hypothesis that selection acts differentially among P. hispanicus female morphs to create alternative morph-specific phenotypic optima at different levels by investigating whether morphs differ in fitness proxies. We specifically examined whether the two female dorsal pattern morphs differed in adult morphology, dorsal coloration, immune response, reproductive investment, and growth. We did not find a relationship between melanin-based coloration and hatchling growth and immune response, despite a correlation between these traits possibly being expected as a result of pleiotropy in the melanocortin system. However, our results show that female dorsal morphs in P. hispanicus differ in terms of adult morphology, dorsal coloration, and reproductive investment. Reticulated-blotched P. hispanicus females had deeper heads and longer femora, less melanin, and more brownish coloration, and also had larger and heavier hatchlings than striped females.

No abstract