Increase in membrane thickness during development compensates for eggshell thinning due to calcium uptake by the embryo in falcons.

We compared membrane thickness of fully developed eggs with those of non-developed eggs in different endangered falcon taxa. To our knowledge, membrane thickness variation during development has never been examined before in falcons or any other wild bird. Yet, the egg membrane constitutes an important protective barrier for the developing embryo. Because eggshell thinning is a general process that occurs during bird development, caused by calcium uptake by the embryo, eggs are expected to be less protected and vulnerable to breakage near the end of development. Thus, egg membranes could play an important protective role in the later stages of development by getting relatively thicker. We used linear mixed models to explore the variation in membrane thickness (n = 378 eggs) in relation to developmental stage, taxon, female age, mass and identity (73 females), egg-laying sequence (105 clutches) and the study zone. Our results are consistent with the prediction that egg membranes are thicker in fully developed eggs than in non-developed eggs, suggesting that the increase in membrane thickness during development may compensate for eggshell thinning. In addition, our data shown that thicker membranes are associated with larger, heavier and relatively wider eggs, as well as with eggs that had thinner eggshells. Egg-laying sequence, female age and the study zone did not explain the observed variation of membrane thickness in the falcon taxa studied. As we provide quantitative data on membrane thickness variation during development in falcons not subjected to contamination or food limitation (i.e. bred under captive conditions), our data may be used as a reference for studies on eggs from natural populations. Considering the large variation in membrane thickness and the multiple factors affecting on it and its importance in the protection of the embryo, we encourage other researchers to include measurements on membranes in studies exploring eggshell thickness variation.

Nitrates and herbicides cause higher mortality than the traditional organic fertilizers on the grain beetle, Tenebrio molitor.

We examined experimentally whether fertilizers or herbicides commonly used by farmers affect mortality of the adult grain beetle Tenebrio molitor. After a period of 4 weeks in direct contact with all treatments, a higher percentage of mortality occurred in contact with nitrates than with pig manure or turkey litter. Herbicides (a mixture of glyphosate and 2,4-D: ) caused 100% mortality. Our results also indicate that more beetles escaped from the herbicides and nitrate treatments than from the others, suggesting some kind of behavioural avoidance of toxic environments. The traditional organic fertilizers appear to be less toxic than inorganic fertilizers for Tenebrio molitor.

Thermal biology, microhabitat selection, and conservation of the insular lizard Podarcis hispanica atrata.

We studied aspects of the thermal biology and microhabitat selection of the endangered lizard Podarcis hispanica atrata during autumn in the field and laboratory. Body temperatures (T b ) of active lizards were within a narrow range, were largely independent of ambient temperatures, and exhibited little diel variation. Activity T b s largely coincided with the selected temperatures maintained in a laboratory thermogradient and with T b s that maximize running performance. Alternation of basking with other activities and shuttling between sun and shade were obvious aspects of thermoregulatory behaviour. Lizards shifted microhabitat use throughout the day. During early morning and late afternoon, basking lizards were restricted to rocky sites surrounded by shrubs. Near midday lizards used a wider array of microhabitats, and many moved in open grassy sites. Juveniles maintained lower activity T b s, had lower selected temperatures, and basked less frequently than the adults. Juveniles occupied open grassy patches more often than the adults. We discuss the relevance of our results for the conservation of this extremely rare lizard and the management of its habitats.

Altitudinal variation of the thermal biology and running performance in the lizard Podarcis tiliguerta.

We studied, in the field and laboratory, aspects of the thermal biology in two populations of the lizard Podarcis tiliguerta along a 1450 m altitudinal gradient. Body temperatures (Tb) at high altitudes average lower, are more variable, but are more elevated above environmental temperatures than at sea level. Lizards partially reduced the impact of altitudinal changes in thermal loads through presumable subtle behavioural adjustments. A comparison of the thermal preferences in the laboratory, the maximal operative temperatures predicted from a biophysical model, and the activity Tb's at both sites, indicates that the main response to changing environmental conditions is an active shift in thermoregulatory set points. Integration of field Tb's and laboratory data on temperature specific sprint speeds, predicts that the mountainous lizards experience reduced running abilities that are especially acute in the early morning. Despite this impairment of running performance, the thermal sensitivity of running speed has not evolved to match the Tb's experienced by both populations. This result supports the view that the thermal physiology of this lizard is evolutionarily conservative, but the lack of information on the relation between running performance and fitness components impedes rejection of alternative hypotheses.

A preliminary report on the distribution of lizards in Qatar.

We have updated the list of the lizard species present in Qatar and produced the first distribution maps based on two field surveys in 2012 and 2013. We used the QND95/Qatar National Grid with a grid of 10 × 10 km squares for mapping. Our results show the occurrence of 21 lizard species in Qatar, from the 15 species indicated in the last biodiversity report conducted in 2004. The most abundant family found in Qatar is Gekkonidae with nine species (Bunopus tuberculatus, Cyrtopodion scabrum, Hemidactylus robustus, H. flaviviridis, H. persicus, Stenodactylus arabicus, S. slevini, S. doriae, Pseudoceramodactylus khobarensis), followed by Lacertidae with four species (Acanthodactylus schmidti, A. opheodurus, Mesalina brevirostris, M. adramitana), Agamidae with three species (Trapelus flavimaculatus, Uromastyx aegyptia, Phrynocephalus arabicus), Scincidae with two species (Scincus mitranus, Trachylepis septemtaeniata), and Varanidae (Varanus griseus), Sphaerodactylidae (Pristurus rupestris) and Trogonophiidae (Diplometopon zarudnyi) with one species each. The species richness fluctuated largely across Qatar between one and eleven species per grid square. We believe that the lizard fauna records in Qatar are still incomplete and that additional studies are required. However, our study here fills a gap concerning lizard biodiversity knowledge in the Gulf Region.

The effect of developmental stage on eggshell thickness variation in endangered falcons.

We compared eggshell thickness of hatched eggs with that of non-developed eggs in endangered falcon taxa to explore the effect of embryo development on eggshell thinning. To our knowledge, this has never been examined before in falcons, despite the fact that eggshell thinning due to pollutants and environmental contamination is often considered the most common cause of egg failure in falcons. Because of the endangered nature of these birds, and the difficulty in gaining access to the nests and their eggs, there is a large gap in our knowledge regarding eggshell thickness variation and the factors affecting it. We used a linear mixed-effects (LME) model to explore the variation in eggshell thickness (n=335 eggs) in relation to the developmental stage of the eggs, but also in relation to the falcon taxa, the laying sequence and the study zone. Female identity (n=69) and clutch identity (n=98) were also included in the LME model. Our results are consistent with the prediction that eggshell thickness decreases during incubation because of the important effect of calcium uptake by the embryo during development. Our results also show that eggs laid later in the sequence had significantly thinner eggshells. In this study, we provide the first quantitative data on eggshell thickness variation of hatched eggs in different falcon taxa that were not subjected to contamination or food limitation (i.e., bred under captive conditions). Because eggshell thickness strongly influences survival and because the species examined in this study are endangered, our data represent a valuable control for future studies on the effects of pollution on eggshells from wild populations and thus are an important contribution to the conservation of falcons.

Determinants of eggshell strength in endangered raptors.

We compared eggshell strength in a group of falcon taxa including the peregrine falcon (Falco peregrinus peregrinus), the red shaheen falcon (F. peregrinus babylonicus), the saker falcon (F. cherrug), the gyr falcon (F. rusticolus) and some interspecific and intraspecific hybrids. Our results showed that smaller falcons (<1,000 g) of the peregrine group have eggshells that are significantly softer (x=13.3 N) and thinner (x=0.26 mm) (n=107 eggs) than larger falcons (>1,000 g) of the gyr-saker group (x=20.8 N and 0.39 mm, respectively, n=81 eggs). We found a significant positive correlation between egg hardness and eggshell thickness. Linear mixed models showed that clutches from heavier females consisted of larger and harder eggs with thicker shells and thicker egg membranes. Eggs produced by older females and eggs laid later in the laying sequence were relatively smaller and softer and had relatively thin egg membranes and eggshells. Individual females, irrespective of their age, contributed significantly to the observed variation in egg strength. Egg size and hardness of hybrid eggs were similar to that of the pure species suggesting that hybridization does not affect eggshell hardness or thickness. Our study provides quantitative evidence of several factors, other than levels of contamination, which may affect eggshell thickness and hardness in falcons.

Developmental stage affects eggshell-breaking strength in two ground-nesting birds: the partridge (Alectoris rufa) and the quail (Coturnix japonica).

We examined the relationship between embryo development and egg hardness in two ground nesting bird species, the red-legged partridge (Alectoris rufa; n = 165 eggs) and the quail (Coturnix japonica; n = 148 eggs). For both species, we observed a strong effect of developmental stage on egg hardness. Eggs near hatching were significantly weaker than unincubated eggs (partridge: 18 and 23 N, respectively, and the quail 7 and 10 N, respectively). We additionally explored the effect of incubation on egg hardness in a control sample of non-fertilised quail eggs (i.e., without embryo development). The control eggs maintained in the incubator for the full incubation time (17 days) were significantly harder (7-9 N) than eggs containing fully developed chicks (5-7 N). Thus, the incubation conditions of high temperature and humidity alone seem not to have a significant effect on egg hardness, and support the important effect of calcium uptake.

EVOLUTION OF SPRINT SPEED IN LACERTID LIZARDS: MORPHOLOGICAL, PHYSIOLOGICAL, AND BEHAVIORAL COVARIATION.

Organismal performance abilities occupy a central position in phenotypic evolution; they are determined by suites of interacting lower-level traits (e.g., morphology and physiology) and they are a primary focus of natural selection. The mechanisms by which higher levels of organismal performance are achieved during evolution are therefore fundamentally important for understanding correlated evolution in general and coadaptation in particular. Here we address correlated evolution of morphological, physiological, and behavioral characteristics that influence interspecific variation in sprint speed in a clade of lacertid lizards. Phylogenetic analyses using independent contrasts indicate that the evolution of high maximum sprinting abilities (measured on a photocell-timed racetrack) has occurred via the evolution of (1) longer hind limbs relative to body size, and (2) a higher physiologically optimum temperature for sprinting. For ectotherms, which experience variable body temperatures while active, sprinting abilities in nature depend on both maximum capacities and relative performance levels (i.e., percent of maximum) that can be attained. With respect to temperature effects, relative performance levels are determined by the interaction between thermal physiology and thermoregulatory behavior. Among the 13 species or subspecies of lizards in the present study, differences in the optimal temperature for sprinting (body temperature at which lizards run fastest) closely matched interspecific variation in median preferred body temperature (measured in a laboratory photothermal gradient), indicating correlated evolution of thermal physiology and thermal preferences. Variability of the preferred body temperatures maintained by each species is, across species, negatively correlated with the thermal-performance breadth (range of body temperatures over which lizards can run relatively fast). This pattern leads to interspecific differences in the levels of relative sprint speed that lizards are predicted to attain while active at their preferred temperatures. The highest levels of predicted relative performance are achieved by species that combine a narrow, precise distribution of preferred temperatures with the ability to sprint at near-maximum speeds over a wide range of body temperatures. The observed among-species differences in predicted relative speed were positively correlated with the interspecific variation in maximum sprinting capacities. Thus, species that attain the highest maximum speeds are (1) also able to run at near-maximum levels over a wide range of temperatures and (2) also maintain body temperatures within a narrow zone near the optimal temperature for sprinting. The observed pattern of correlated evolution therefore has involved traits at distinct levels of biological organization, that is, morphology, physiology, and behavior; and trade-offs are not evident. We hypothesize that this particular trait combination has evolved in response to coadaptational selection pressures. We also discuss our results in the context of possible evolutionary responses to global climatic change.