Alfredo Salvador

Tail loss reduces mating success in the Iberian rock-lizard, Lacerta monticola

SummaryMany lizards autotomize their tails to escape when grasped by a predator. It is hypothesized that tail loss causes a reduction in social status, thereby potentially lowering their reproductive success. We experimentally induced tail loss in Lacerta monticola in a semi-natural enclosure, and show that tail loss reduced social status and mating access in males. Tailless males increased body mass more rapidly than tailed dominant males, probably due to lower aggression costs. Also, tailless females were courted less and copulated less than tailed females, supporting the hypothesis that tail loss decreases reproduction potential.

Tail loss consequences on habitat use by the Iberian rock lizard, Lacerta monticola

Habitat preferences in lizards are often associated with specific morphological traits and locomotor behavior. Caudal autotomy occurs in many lizards and is often used for escape from predators. Autotomy produces an immediate benefit in terms of survival, although associated costs during tail regeneration may reduce individual fitness. Tail loss may affect the efficiency with which lizards use their habitat. We investigated experimentally the effect of tail loss on microhabitat use in a population of the Iberian rock lizard, Lacerta monticola

Thermoregulatory Behaviour of Rock Lizards in Response To Tail Loss

The consequences of tail loss on the thermal biology of high-altitude rock lizards (Lacerta monticola) were studied by comparing field body temperatures, selected body temperatures in a gradient, and behavioural patterns of thermoregulation of tailed and tailless lizards in the field. Neither field nor selected body temperatures differed significantly between these groups. Time spent basking, mean duration of basking, and basking frequency did not differ between tailed and tailless lizards. Tailless lizards seemingly adjusted for running impairment by using rocks to a greater extent than did tailed lizards, and low morning body temperatures by increasing maximal duration of basking periods and keeping shorter distances to the nearest refuge. Tailless lizards modify thermoregulatory behaviour, but obtain the same thermoregulatory precision as tailed lizards, possibly allowing maximization of physiological processes linked to tail regeneration.

Reproductive effort affects immune response and parasite infection in a lizard : a phenotypic manipulation using testosterone

Life-history theory predicts that there is a trade-off between reproductive effort and several traits that determine fitness. Infectious disease has gained acceptance as a crucial factor linking both variables. In most instances phenotypic manipulation is necessary to convincingly demonstrate a causal relationship of reproductive effort on parasitism. However, experimental studies that manipulate reproductive effort or parasite load have been rarely conducted in reptiles. In this study. we manipulated reproductive effort of male lizards (Psammodromus algirus) through testosterone implants, and measured the associated response in some haematological variables and parasite load. Testosterone-supplemented males had lower scores than control males in factor I of a PCA for different blood parameters. This factor is correlated with the number of white blood cells, especially lymphocytes, and with plasma glucose levels. Experimental males also had higher scores in factor 3 that is mainly related to protein catabolism. Scores of males in component I tended to be correlated negatively with tick load, while scores in component 3 were correlated positively with the number of haemogregarines in the blood. These results suggest that higher investment in reproduction decreases the immune defences. and conduces to the use of structural resources, which may render individuals more susceptible to some haemoparasites. This is consistent with the idea that an increase in reproductive effort mediated by testosterone has a negative effect on the ability to counteract parasite infections.

Microhabitat selection by the Iberian rock lizard Lacerta monticola: Effects on density and spatial distribution of individuals

We describe microhabitat selection in the Iberian rock lizard Lacerta monticola, a species endemic to some high mountains of the Iberian peninsula. This species is potentially threatened, in particular, by changes in habitat conditions on the ski slopes and from associated buildings in resorts that proliferate precisely in areas it favours. We analyse the relationship between habitat physical structure and population densities, in order to establish a predictive habitat-population model. Lizards select large rock screes and Cytisus bushes, but scarcely use Juniperus bushes and grassy areas. Individuals have an aggregated spatial distribution. The application of this habitat model may allow predictions to be made about the response of L. monticola to artificial and natural habitat changes, and could help to manage suitable habitats for populations.

Tail Loss and Foraging Tactics of the Iberian Rock-Lizard, Lacerta monticola

Many lizards autotomize their tail to escape when attacked by a predator. The foraging tactics of tailless lizards may be affected by changes in behavior aimed at compensating tail loss per se as well as associated costs of regeneration. We tested this hypothesis in a population of the Iberian rock-lizard (Lacerta monticola), during the reproductive season, by comparing the diet of tailed and tailless lizards with the estimated prey availability in their habitat. We also compared the feeding rates, foraging microhabitat and foraging tactics of tailed and tailled lizards. Tail loss did not affect feeding rates, nor did it alter the foraging tactics of either sex during spring

Reproductive Phenology and Temporal Patterns of Mate Access in Mediterranean Anurans

Acknowledgments.-We are indebted to J. H. Harding for field assistance in obtaining the specimens of Storeria occipitomaculata, to H. A. Dundee for helping to support the fieldwork, to K. M. Brown for sharing his knowledge of snail anatomy, to V. Wallach for critically reading the manuscript, and to K. K. Adler, C. P. Kofron, C. J. McCoy, and A. H. Savitzky for providing copies of some difficult-to-find refer-

Body Size and Microhabitat Affect Winter Survival of Hatchling Psammodromus algirus Lizards

To examine factors related to overwinter survival of Psammodromus algirus hatchlings, we performed a capture-mark-recapture study of a cohort of hatchlings. In this work, we examine the effects of body size, vegetation structure of the home range, tail condition, sex, and estimated hatching date on hatchling survivorship to the next spring. Results of a logistic regression analysis showed that survival was associated with larger body size (SVL), higher cover, and earlier hatching date. Tail condition and sex were not associated with overwinter survivorship.

The role of chemosensory cues in discrimination of prey odors by the amphisbaenianBlanus cinereus

Responses of amphisbaenians (Blanus cinereus) to deionized water, a control for pungency (cologne), and integumental prey odors (coleopteran larvae and adult ants) on cotton swabs were studied in experiments with a randomized blocks design to discover whether amphisbaenians use chemical cues to detect and identify prey. No individual bit the applicators. Amphisbaenians tongue-flicked at lower rates than epigean saurians, which are active foragers. Tongue-flick rate differed among treatments, but responses to prey odors were not significantly different from those to cologne. The number of directed tongue-flicks emitted during the 60-sec trials was, however, lower in response to deionized water than in response to cologne or prey odors. Response details, the low rate of tongue-flick, and absence of biting are discussed in relation to the foraging behavior and fossoriality of amphisbaenians. Evidence from this study indicates that the vomeronasal sense is used by amphisbaenians to identify odors, but our experiments failed to demonstrate that amphisbaenians discriminate between prey and nonprey odors.

Testosterone stress does not increase asymmetry of a hormonally mediated sexual ornament in a lizard

Abstract The theory that fluctuating asymmetry is sensitive to both environmental and genetic stress is gaining acceptance among evolutionary biologists. Most empirical work has focused on ornamental traits on the assumption that they are more susceptible to stress. In tegumentary coloration is a common ornament in nature, and frequently has a hormonal basis. Earlier studies in the lizard Psammodromus algirus indicate that testosterone induces the development of head nuptial coloration in large males and, at the same time, produces an increase of the ectoparasite load and higher mortality. Hence, the manipulation of testosterone levels may be a way to increase ornament expression and simultaneously create conditions that may make symmetrical development difficult. This positive covariation between character size and symmetry is opposite to that expected in theory for sexually selected traits, so the predicted elevation of asymmetry due to the treatment cannot be confounded by any intrinsic association between symmetry and character size. We firstly consider the effect that testosterone supplementation has on two variables that reflect the symmetry of bilateral throat nuptial coloration in large P. algirus males. Also, we examine whether ornament symmetry is positively associated with reproductive success, a prediction of theory of sexually selected symmetry. Testosterone treatment did not increase the fluctuating asymmetry of throat coloration. Size asymmetry increased with character size in individuals with a fragmented colour pattern, but changed suddenly to a highly symmetric pattern in individuals with non-fragmented coloration. Mirror asymmetry decreased steadily with character size. These results suggest that the development of coloration on both sides of the throat midline follows a random pattern. Asymmetry did not correlate with variables that estimated reproductive success, suggesting that asymmetry is not affected by physiological stress and that this trait is not a sexually selected signal in P. algirus.