Jesús Ortega

Interpopulational variations in sexual chemical signals of Iberian wall lizards may allow maximizing signal efficiency under different climatic conditions

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.

Phylogeny of the reptilian Eimeria: are Choleoeimeria and Acroeimeria valid generic names?

Reptiles are the animals with the most described coccidian species among all vertebrates. However, the co‐evolutionary relationships in this host–parasite system have been scarcely studied. Paperna & Landsberg (South African Journal of Zoology, 24, 1989, 345) proposed the independent evolutionary origin of the Eimeria‐like species isolated from reptiles based on morphological and developmental characteristics of their oocysts. Accordingly, they suggested the reclassification of these parasites in two new genera, Choleoeimeria and Acroeimeria. The validity of the genera proposed to classify reptilian Eimeria species remained unresolved due to the lack of species genetically characterized. In this study, we included 18S rRNA gene sequences from seven Eimeria‐like species isolated from five different lizard host families. The phylogenetic analyses confirmed the independent evolutionary origin of the Eimeria‐like species infecting lizards. Within this group, most species were placed into two monophyletic clades. One of them included the species with ellipsoidal oocysts (i.e. Choleoeimeria‐like oocysts), whereas the species with more spheroidal oocysts (i.e. Acroeimeria‐like oocysts) were included in the second one. This result supports the taxonomic validity of the genera Acroeimeria and Choleoeimeria.

Reproductive Activity, Diet, and Microhabitat Use in Bolitoglossa nicefori (Caudata: Plethodontidae)

Abstract Bolitoglossa nicefori is a terrestrial salamander only known from its original description. We report the discovery of two populations of this species; analyze annual reproductive activity, diet, and microhabitat use of one population; and compare this information with that known for other species of Bolitoglossa. Sexually mature males ranged between 29 and 50 mm standard length and females between 39 and 75 mm. Histological analyses of testes and ducts revealed the presence of sperm through the year, indicating continuous reproductive activity for males. Adult females were captured year-round; however, reproductive females were observed only during the driest months of the year (November to February), indicating that females have a seasonal reproductive activity. The contents of 89 stomachs were analyzed, and perch height, type of vegetation, and substrate type were registered. The diet of this population consists of 13 items, with ants and coleopterans accounting for 87% of food ingested by the different age and sex classes. Ants represent 58% of the diet, reflecting their greater availability in this microhabitat. Intra- and intersexual differences in diet were not found. Bolitoglossa nicefori exhibited both terrestrial and arboreal behaviors related to temperature and humidity conditions during the daily cycle. Mature nonreproductive females, males, and juveniles were found perching from 0–60 cm above the ground on Araceae bushes that predominate in the study area, whereas reproductive females were always found within the leaf litter. Life-history features of B. nicefori are determined by environmental conditions; however, they follow common trends shared with other species of Bolitoglossa.

Phylogenetic relationships of Isospora, Lankesterella, and Caryospora species (Apicomplexa: Eimeriidae) infecting lizards

In this study, several species of Isospora infecting lizards were genetically characterized. Specifically, five described and four newly described species of Isospora were included in a phylogeny of the family Eimeriidae. These species were isolated from hosts originally inhabiting all geographic continents except Europe. Phylogenetic analyses of the 18S ribosomal RNA (rRNA) gene grouped these nine species of Isospora with Lankesterella species and Caryospora ernsti. Therefore, within this clade, different evolutionary strategies in oocyst development and transmission occurred. Although the characteristic endogenous oocyst development of the genus Lankesterella may have arisen only once, the reduction in the number of sporocysts observed in the genus Caryospora occurred at least twice during coccidian evolution, as evidenced by the phylogenetic position of Caryospora bigenetica as the sister taxon of the group formed by reptilian Isospora, Lankesterella, and C. ernsti. Within this group, C. ernsti was the sister taxon to the genus Lankesterella. Overall, our results contradict the proposed monophyly of the genus Caryospora, highlighting the need for a thorough taxonomic and systematic revision of the group. Furthermore, they suggest that the recent ancestor of the genus Lankesterella may have been heteroxenous.

Altitudinally divergent adult phenotypes in Iberian wall lizards are not driven by egg differences or hatchling growth rates

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 proximate 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 no 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 or 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 are 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.

Diet selection by the threatened Chafarinas' skink Chalcides parallelus in North Africa

Abstract Studies of diet suggest that skinks are opportunistic predators. However, there is little information on actual diet preferences because most studies do not evaluate the availability of prey in the environment. We analysed the diet selection of a population of the little-known skink Chalcides parallelus from the Chafarinas Islands in North Africa. This species is considered highly threatened, and diet selection is an important basic point on which to support the design of conservation plans. We specifically examined diet estimated from faecal material collected from live skinks, and compared diet with availability of invertebrates in the microhabitats used by skinks (under rocks and in the leaf litter). Results indicated that the diet of C. parallelus skinks consisted of the same types of invertebrates that are more commonly found in the habitat such as beetles (54.8% of prey), cockroaches, spiders and snails. This diet could be considered generalist, and probably opportunistic. However, the comparison of proportions of prey types in the diet and those available in the habitat revealed that C. parallelus did not eat prey at random, but selected some particular prey types (beetles, cockroaches, and pseudoscorpiones) while others (ants and isopods) were consumed less than expected by their abundance. Invertebrates available and consumed did not differ in size, but skinks consumed beetles that were smaller than the average size of those available. We discuss how diet preferences could be due to selection of the more profitable or easily captured prey.

Chemosensory Prey Detection by the Amphisbaenian Trogonophis wiegmanni

Abstract Foraging underground poses a number of important challenges for fossorial animals, such as amphisbaenians. For instance, visual detection and identification of prey is often hampered by low light conditions and poor eye sight. In response, many fossorial animals have switched to other sensory systems, such as chemoreception. We tested the ability of the amphisbaenian Trogonophis wiegmanni to detect and discriminate between different prey types based on chemical cues alone. Results of a laboratory experiment showed that amphisbaenians were able to detect prey using chemoreception, as indicated by an increase in chemosensory tongue-flick responses to swabs bearing chemicals from prey in comparison with blank controls. Also, differential tongue-flick rates to chemicals from different prey types indicated that at least some prey types may be discriminated from others based on chemosensory cues. These results suggest that T. wiegmanni amphisbaenians use chemoreception when foraging.

Chemical Compounds from the Preanal Gland Secretions of the Male Tree Agama (Acanthocercus atricollis) (Fam. Agamidae)

Chemical signals have an important role in the reproductive behaviour of many lizards. However, the compounds secreted by their femoral or preanal glands, which may be used as sexual signals, are mainly known for lizard species within the Scleroglossa clade, whereas compounds in secretions of lizards within the Iguania clade are much less studied. Based on mass spectra, obtained by GC-MS, we found 60 lipophilic compounds in preanal gland secretions of the male tree agama (Acanthocercus atricollis) (fam. Agamidae), including steroids (mainly cholesterol, cholest-3-ene, and some of their derivatives), fatty acids ranging between n-C12 and n-C18 (mainly hexadecanoic and octadecenoic acids), ketones from n-C17 to n-C25, and other minor compounds, such as tocopherol, squalene, waxy esters, and furanones. We compare the compounds found with those present in other lizard species and discuss their potential function in social behaviour

Interpopulational and seasonal variation in the chemical signals of the lizard Gallotia galloti

Communicative traits are strikingly diverse and may vary among populations of the same species. Within a population, these traits may also display seasonal variation. Chemical signals play a key role in the communication of many taxa. However, we still know far too little about chemical communication in some vertebrate groups. In lizards, only a few studies have examined interpopulational variation in the composition of chemical cues and signals and only one study has explored the seasonal effects. Here we sampled three subspecies of the Tenerife lizards (Gallotia galloti) and analyze the lipophilic fraction of their femoral gland secretions to characterize the potential interpopulational variation in the chemical signals. In addition, we assessed whether composition of these secretions differed between the reproductive and the non-reproductive season. We analyzed variations in both the overall chemical profile and the abundance of the two main compounds (cholesterol and vitamin E). Our results show interpopulational and seasonal differences in G. gallotia chemical profiles. These findings are in accordance with the high interpopulational variability of compounds observed in lizard chemical signals and show that their composition is not only shaped by selective factors linked to reproductive season.

Experience may allow increasing accuracy of the innate chemosensory recognition of snake predators by Iberian wall lizards

Many animals can recognize chemical cues of predators and show defensive responses, but antipredatory behavior can be costly and should be modulated depending on the level of risk posed by each predatory species. Recognition ability may be innate, but it is not clear whether there might also be local adaptation to predation pressure levels or some learning component. We examined the chemosensory ability of naïve and adult Iberian wall lizards, Podarcis hispanicus, to detect chemical cues of two closely related Coronella snake species in two localities within the same continuous population. Lizards in each locality are sympatric with only one of the two snake species. Our results showed an innate chemosensory discrimination of predatory snake cues, as both adult lizards and captive reared naïve hatchlings, which had not had any previous experience with the snake cues, had short latencies to the first tongue-flick, increased tongue-flick responses, and active escape behavior from the scent of either of the two snake species. Moreover, adult lizards, but not naïve hatchlings, showed differential responses to the two different snake species, with higher responses to the snake species that is sympatric in each locality. This strongly suggests that there is a learning component acquired through previous lifetime experiences that may increase accuracy of the discrimination of the sympatric snake. Therefore, through learning of local conditions, lizards may modulate their innate antipredatory responses to the risk level posed by each snake species.