Interactions between Males of the Lizard Liolaemus tenuis: Roles of Familiarity and Memory

For territorial organisms, recognition of familiar individuals can reduce the frequency and intensity of aggressive encounters (‘dear enemy’ phenomenon), stabilize social systems, and reduce the cost of territory maintenance. Here, we investigated the behavioural events displayed during contests between familiar and unfamiliar individuals in the lizard Liolaemus tenuis (Liolaemidae), a species in which males are territorial. The behaviours recorded were attack, warning, evasion, and submission, and the latencies to the first aggressive (attack or warning) behaviour. Additionally, we assessed the ability of individuals to remember a familiar conspecific after a period without social interaction. Individual males reduced and delayed aggressive behaviour directed towards socially familiar individuals compared with unfamiliar ones. These results suggest that males distinguished between familiar and unfamiliar conspecific males and are in agreement with the ‘dear enemy’ phenomenon. Other behaviours were similar in the contests between familiar and unfamiliar individuals. Recognition of familiar conspecifics was lost after 20 d without social interactions. This may be relevant for interactions with floater males or with neighbours that lose their territory and subsequently attempt to fight for their ex‐neighbour's territory.     

Comparative analysis of the development of the lizard,Liolaemus tenuis tenuis. II. A series of normal postlaying stages in embryonic development

In this work, we have completed a study of the development of the ovoviviparous lizard Liolaemus tenuis tenuis. Ovoviviparity in this lizard is a condition in which eggs are retained within the reproductive duct for about 60 days. During this period the phases of segmentation, gastrulation, neurulation, presomitic, and somitic embryos transpire. During the months of December and January the eggs are laid, and at this time the embryos are comparable to stage 27 Liolaemus gravenhorsti lizard embryos, or to stage 29 Calotes versicolor lizard embryos. Differentiation of the facial region occurs between Days 12 and 42 after egg laying. Limbs develop rapidly between the 8th and 23rd days. By 53 days the appendicular skeleton is completely formed. After 36 days the mesonephros begins to degenerate, and its function is gradually taken over by the developing metanephros. Newborn lizards do not possess an egg caruncle. During the period up to hatching, there is a great increase of liquid within the egg, presumably amniotic fluid. Cracks develop in the leathery shell shortly before hatching and are, perhaps, the first sign of the onset of hatching. Increase of liquid in the egg during postlaying development accounts for its increase in weight and change in shape. Weight of the embryo at hatching does not exceed 32% of the total weight of the egg.     

Ectoparasitism by Eutrombicula alfreddugesi larvae (Acari: Trombiculidae) on Liolaemus tenuis lizard in a Chilean fragmented temperate forest

We compared parasite load (prevalence and mean intensity) of Eutrombicula alfreddugesi larvae on the lizard Liolaemus tenuis sampled during January 2006 and 2007 from the interior and edges of large forest tracts in the coastal Maulino Forest (35 degrees 59'S, 72 degrees 41'W) and from nearby forest fragments (1.5-20 ha). All lizards were parasitized by chiggers regardless of location (prevalence, 100%); however, mean intensity of infestation was significantly lower at forest fragment edges compared with either large forest interiors or forest edges. We attribute differences in mean intensity to differences in microclimate among localities; maximum air temperature was significantly higher and relative humidity significantly lower in fragment edges compared with either large forest tract interior or edges.     

Cannibalism in the Andean lizard Liolaemus orientalis

Cannibalism is a recurrent behavior across the animal kingdom, with important ecological and evolutionary consequences due to its potential trade-offs on the fitness of involved individuals and demography dynamics. Cannibalism has been reported in eight species of several phylogenetic lineages within Liolaemus, a highly diverse genus of Neotropical lizards. Within the Liolaemus montanus series, two species are reported to eat juveniles in captivity. We observed a female Liolaemus orientalis, another L. montanus series member, which had ingested a juvenile of its own species in the wild. As it generally happens with other lizards, cannibalism in Liolaemus has been suggested to be performed by the larger sex, with L. chiliensis being the only other case observed until now in which the cannibalistic individual was a female. The fact that females are slightly smaller than males in L. orientalis means that our observation is an exception to previously observed trends. We suggest that there is a relationship between this behavior and the presence of a masculine trait in the cannibalistic female: developed precloacal pores. We also discuss how refuge availability may influence demography and the probability of dispersing juveniles encountering adults, increasing the chances for cannibalism to play some role in population density regulation.     

Chemical self-recognition in the lizard Liolaemus fitzgeraldi

Social–chemical recognition is exhibited by all the Liolaemus lizards tested to date, except Liolaemus fitzgeraldi, which during post-hibernation did not discriminate chemosignals of same-sex individuals from a control. To clarify if L. fitzgeraldi is unique among the studied Liolaemus in lacking social–chemical recognition or if this was previously undetected, we recorded behavior during pre- and post-hibernation when confronted with chemosignals of conspecifics and from themselves. L fitzgeraldi showed self-recognition and seasonal changes in two exploratory behaviors. Potentially, conspecific recognition in L fitzgeraldi was undetected due to seasonality, but this species may rely comparatively less on chemical communication than congeners.     

Nuclear distribution in Alternaria tenuis

Nuclear distribution and behaviour during vegetative growth and spore formation inAlternaria tenuis was studied utilising the HCl — Giemsa staining technique. The vegetative mycelium and conidia are predominantly monokaryotic. Anastomoses, followed by nuclear migrations, have been recorded. Intercellular nuclear migrations have only been observed in germinating conidia. Nuclear behaviour during conidial formation indicates that the conidia are homokaryotic. Cytological differences have been found in different monocoidal isolates of A. tenuis.     

Environmental correlates of phenotypic evolution in ecologically diverse Liolaemus lizards

Evolutionary correlations between phenotypic and environmental traits characterize adaptive radiations. However, the lizard genus Liolaemus, one of the most ecologically diverse terrestrial vertebrate radiations on earth, has so far shown limited or mixed evidence of adaptive diversification in phenotype. Restricted use of comprehensive environmental data, incomplete taxonomic representation and not considering phylogenetic uncertainty may have led to contradictory evidence. We compiled a 26‐taxon dataset for the Liolaemus gracilis species group, representing much of the ecological diversity represented within Liolaemus and used environmental data to characterize how environments occupied by species'' relate to phenotypic evolution. Our analyses, explicitly accounting for phylogenetic uncertainty, suggest diversification in phenotypic traits toward the present, with body shape evolution rapidly evolving in this group. Body shape evolution correlates with the occupation of different structural habitats indicated by vegetation axes suggesting species have adapted for maximal locomotory performance in these habitats. Our results also imply that the effects of phylogenetic uncertainty and model misspecification may be more extensive on univariate, relative to multivariate analyses of evolutionary correlations, which is an important consideration in analyzing data from rapidly radiating adaptive radiations.     

Alternaria tenuis Auct. in Bombay-Maharashtra

Summary This paper gives an account of distribution, host range and economic importance of the speciesAlternaria tenuis Auct, as it occurs in Bombay-Maharashtra (India). The species has been collected on 51 hosts distributed among 23 host families of which 5 are new host records not previously reported in literature.Part of the author's Ph. D. (Agri.) thesis approved by the University of Poona, Poona (India), 1964.Junior Research Fellow of the University Grants Commission, New Delhi, (India) in Mycology and Plant Pathology.     

Zoophytophagy in the plantbug Nesidiocoris tenuis

1 The zoophytophagy of Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) was characterized in relation to prey availability and environmental factors by: (i) monitoring its population dynamics in tomato greenhouses; (ii) analysis of the influence of N. tenuis and whitefly density, temperature and humidity on the intensity of N. tenuis plant feeding; and (iii) laboratory assays under controlled conditions to determine the intensity of plant feeding in relation to prey availability, temperature and humidity. 2 A negative relationship was found between plant feeding and predated whiteflies in tomato greenhouses. Plant feeding was directly related to N. tenuis density and temperature and inversely related to whitefly density. The significance of prey availability and temperature was corroborated in laboratory assays. The intensification of plant feeding at low prey density indicates switching from zoophagy to phytophagy as prey become scarce. 3 Nesidiocoris tenuis showed a typical predator dynamic in relation to variance in prey density. Populations increased after whitefly outbreaks and decreased after whitefly had been depleted. The rapid decrease of N. tenuis populations after whitefly decreased, however, suggests that plants are a poorer nutrient source than whitefly for this species.     

Ecological species replacement of Liolaemus lizards along a habitat gradient

Summary Ecological species replacement of Liolaemus platei by Liolaemus lemniscatus appears to occur along a north-south oriented herb density gradient. Both congeners are the only ground-dwelling lizards in the area; this suggests that L. lemniscatus is an ecological counterpart of L. platei in herbaceous habitats. Relatively longer legs appear to be associated with the utilization of herb-free habitats by L. platei; the shorter legs possessed by L. lemniscatus are associated with the utilization of habitats of higher herb density. Morphological evidence indicates the presence of intermediate populations in the zone of intermediate herb density. Alternatives of a single-species cline versus interspecific hybridization between the two taxa are discussed.     

Chasing the Patagonian sun: comparative thermal biology of Liolaemus lizards

The importance of the thermal environment for ectotherms and its relationship with thermal physiology and ecology is widely recognized. Several models have been proposed to explain the evolution of the thermal biology of ectotherms, but experimental studies have provided mixed support. Lizards from the Liolaemus goetschi group can be found along a wide latitudinal range across Argentina. The group is monophyletic and widely distributed, and therefore provides excellent opportunities to study the evolution of thermal biology. We studied thermal variables of 13 species of the L. goetschi group, in order to answer three questions. First, are aspects of the thermal biology of the L. goetschi group modelled by the environment or are they evolutionarily conservative? Second, have thermal characteristics of these animals co-evolved? And third, how do the patterns of co-evolution observed within the L. goetschi group compare to those in a taxonomically wider selection of species of Liolaemus? We collected data on 13 focal species and used species information of Liolaemus lizards available in the literature and additional data obtained by the authors. We tackled these questions using both conventional and phylogenetically based analyses. Our results show that lizards from the L. goetschi group and the genus Liolaemus in general vary in critical thermal minimum in relation to mean air temperature, and particularly the L. goetschi group shows that air temperature is associated with critical thermal range, as well as with body temperature. Although the effect of phylogeny cannot be ignored, our results indicate that these thermal biology aspects are modelled by cold environments of Patagonia, while other aspects (preferred body temperature and critical thermal maximum) are more conservative. We found evidence of co-evolutionary patterns between critical thermal minimum and preferred body temperature at both phylogenetic scales (the L. goetschi group and the extended sample of 68 Liolaemus species).     

Plantless rearing of the zoophytophagous bug Nesidiocoris tenuis

Nesidiocoris tenuis Reuter (Heteroptera: Miridae) is widely distributed in the Mediterranean area, where it is used as an augmentative biological control agent of several pests. This zoophytophagous predator maintains a close relationship with its host plants using them not only to feed on, but also as an oviposition substrate. In the present study, a plantless rearing system was developed and developmental and reproductive parameters of bugs that had no access to plant material were compared with their counterparts living on plants. Eggs deposited in an artificial substrate took longer to develop and had lower hatching rates than those laid in tomato leaves. However, the biological parameters of nymphs that had hatched from the artificial substrate did not differ from those of nymphs that had emerged from plants, suggesting that, besides water, no essential nutrients are absorbed from the oviposition substrate during embryogenesis. Our results regarding the role of plant feeding indicate that water acquisition is the critical function of phytophagy in N. tenuis. In addition, supplementary nutrients derived from plants had a positive effect on adult weight and significantly enhanced survival in the absence of prey. Plantless rearing for five generations led to a prolonged preoviposition period and lower egg hatching rates and adult weights, but other developmental and reproductive parameters were not adversely affected. Our experiments suggest that prolonged plantless rearing of N. tenuis is possible provided that the mirid has access to a nutritionally superior food like Ephestia kuehniella eggs.     

Latitudinal comparison of the thermal biology in the endemic lizard Liolaemus multimaculatus

Thermoregulation in ectotherms may be modulated by climatic variability across geographic gradients. Environmental temperature varies along latitudinal clines resulting in heterogeneous thermal resource availability, which generally induces ectotherms to use compensatory mechanisms to thermoregulate. Lizards can accommodate to ambient temperature changes through a combination of adaptive evolution and behavioral and physiological plasticity. We studied the thermal ecology of the endangered endemic lizard Liolaemus multimaculatus at six different sites distributed from the northern to southern areas of the distribution (700 km) in the Atlantic dune barriers of Argentina, and even including the borders areas of the distribution range. Environmental temperatures and relative humidity showed a strong contrast between northern and southern limits of the distribution range. The northern localities had operative temperatures (Te) above the range of preferred temperatures (Tset), instead, the southern localities had large proportion of Tes within the Tset. Although these different climatic conditions may constrain the thermal biology of L. multimaculatus, individuals from all localities maintained relatively similar field body temperatures (XTb = 34.07 ± 3.02 °C), suggesting that this parameter is conservative. Thermal preference partially reflected latitudinal temperature gradient, since lizards from the two southernmost localities showed the lowest Tsel and Tset. Thermoregulatory efficiency differed among localities, since E values in the northern localities (E = 0.53–0.69) showed less variability than those of southern localities (E = 0.14–0.67). Although L. multimaculatus employed a strategy of having a conservative Tb and being able to acclimatize the thermal preference to copes with latitudinal changes in the thermal environment, other local factors, such as ecological interactions, may also impose limitations to thermoregulation and this may interfered in the interpretation of results at wider spatial scale.     

Molecular evidence for a species complex in the patagonian lizard Liolaemus bibronii and phylogeography of the closely related Liolaemus gracilis (Squamata: Liolaemini)

The lizard genus Liolaemus is endemic to temperate South America and includes 190 species. Liolaemus bibronii has a large geographic distribution and inhabits a great diversity of habitats, including the Monte, Steppe, and high Andean grassland environments. Liolaemus gracilis has a similar body size and shape to L. bibronii; the two are parapatrically distributed, and L. gracilis is also widely distributed. Here we use the mtDNA cytb sequence data of these two species to investigate lizard phylogeographic patterns in southern South America. L. bibronii is paraphyletic with respect to L. gracilis, Liolaemus ramirezae, Liolaemus robertmertensi and Liolaemus saxatilis; it is composed of many genetically different allopatric haploclades, some of which are reciprocally monophyletic. We also found evidence for introgression between L. bibronii and L. gracilis in the same area that introgression was hypothesized in the Liolaemus darwinii complex. We discuss the distribution of the major haploclades with inferences of their population histories, the concordance of these clades' distributions and histories with other lizard complexes studied with the same markers and methods, and taxonomic implications of these results.     

Variability in the Assessment of Snake Predation Risk by Liolaemus Lizards

The ability to assess and respond to predation risk is a strong selective force. Detection of predators is carried out by one or more sensory modalities, but the use of chemoreception has significant advantages. This study examines the chemosensorial assessment of snake predation risk and corresponding behaviours in different species and populations of Liolaemus lizards naturally exposed to different levels of snake predation pressure. The species studied were sympatric (Liolaemus lemniscatus), parapatric (L. nigroviridis) and allopatric (L. fitzgeraldi) to the saurophagous snake, Philodryas chamissonis. Additionally, two populations of L. lemniscatus from areas differing in snake densities were compared. Chemo‐assessment of predation risk was determined by comparing the number of tongue‐flicks (TF) and the behavioural responses of lizards submitted to three treatments (with semiochemicals of snake, conspecifics, and without semiochemicals – control). The results suggest that Liolaemus lizards can chemo‐assess snake predation risk, but this was modulated by the predation pressure experienced by lizards in their natural habitats. When exposed to snake semiochemicals, the sympatric prey showed less chemical exploratory behaviour (i.e. lower number of TF), a higher frequency of antipredator behaviours that would reduce its detection by a predator, and did not show the behaviour triggered by conspecific semiochemicals. The parapatric prey showed similar number of TF across different treatments, suggesting an absence of recognition of snake semiochemicals; however, it did show antipredatory behaviours when confronted with snake semiochemicals. The allopatric prey showed similar behaviour in all treatments. Both populations of the sympatric species, L. lemniscatus, showed a similar ability to detect predation risk when confronted with snake semiochemicals (i.e. similar number of TF), but antipredatory behaviours were diminished, and marking behaviours were present in the population subject to lower predation pressure. Relaxed predation pressure from a predator that releases and detects semiochemicals had similar consequences at species and population levels.     

The fine structure of the planarianPolycelis tenuis ijima

Summary The fine structure of the pharynx is presented and demonstrates that the pharyngeal epithelial system is a continuous one. The epithelial lining of the pharyngeal cavity with its characteristic fibrous secretory bodies merges with the outer pharyngeal epithelium at the point of anchorage of the pharynx. A few of these cells are insunk, the nuclei occurring beneath the underlying muscular layers. The nature of the outer epithelium changes towards the free end of the pharynx; the cells become ciliated and in contents come to resemble the inner epithelium which it joins at the tip.The gut cells merge at a transitional zone with the inner pharyngeal epithelium and at this point both bear microvilli and contain rod-shaped apical bodies. Some of these cells are also insunk. Towards the mouth the epithelium shows a greater degree of insinking and exhibits microapocrine secretion. Both inner and outer epithelia bear sense receptors which are concentrated at the lip.At the point of pharyngeal insertion, the sub-epithelial tissue resembles planarian parenchyma, but is rich in gland cells. These glands open on to the outer epithelium especially towards the free end of the pharynx.This research was supported by the Scientific Research Council. Grant No. B/RG/086.