The large and diverse genus Penstemon (ca. 271 species) is endemic to North America and has been divided into six subgenera primarily based on anther dehiscence patterns. Species of Penstemon are known to be pollinated by a variety of insects (hymenopterans, lepidopterans, dipterans) and hummingbirds. Nucleotide sequence data from ITS and two noncoding regions of chloroplast DNA were used to reconstruct the phylogeny of Penstemon. Trees generated from nuclear and chloroplast DNA sequences are incongruent, which is probably the result of hybridization, and not fully resolved, which is likely due to a rapid evolutionary radiation. Penstemon represents a recent continental radiation where speciation has resulted primarily from evolutionary adaptations to ecological niches such as pollinator specialization. The results from these analyses show that the current circumscription of subgenera and sections needs revision to reflect more closely the evolutionary relationships of species. Specifically, species in subgenera Saccanthera, Habroanthus, and Penstemon are polyphyletic. These results also confirm the independent origin of hummingbird floral morphology in 10 clades.

Summary 1.In reptiles, growth is subject to proximate environmental influences, such as food availability and temperature, that may be crucial during the early stages of postnatal development. Mediterranean regions, with their severe summer drought, offer an excellent opportunity to examine the effects of environmental variations in precipitation and productivity on the timing of reproduction and growth rates of lizards. 2. In this study, we compared the incubation time, size at hatching, growth rates and changes in juvenile body condition of two nearby populations of the lizard Psammodromus algirus separated by 600-700 m altitude in central Spain. We combined a reciprocal incubation experiment at 27 and 30 ° C with a reciprocal transplant experiment to distinguish between environmental and population-specific sources of geographical variation. 3. At both temperatures, eggs from the high-elevation site hatched sooner. Several important phenotypic traits of juveniles were primarily determined by the growing environment: the high-elevation site provided more food and allowed hatchlings to grow faster and reach larger size. 4. Environmental effects overrode familial ones, as shown by the larger growth rate of half-sibs released at the high-elevation site. However, both the size and the growth rate of juveniles were also influenced by their mother's site of origin, which means that population differences may reflect a genetic differentiation and/or different maternal effects. 5. Low precipitation and associated food scarcity were seemingly the main factors constraining the growth rates of juveniles at the lowland site.

Summary 1.Although thermal factors are of paramount importance to the quality of the habitats occupied by small ectotherms (e.g. lizards), the hypothesis that the relative abundance of squamate populations is related to the thermal quality of their habitats remains untested. If differences in the availability of thermally suitable microhabitats was the primary determinant of the overall quality of a lizard's habitat, population density in a habitat should be proportional to its thermal quality. 2. The influence of the thermal quality of a habitat on thermoregulatory behaviour, body temperatures, expected physiological performance and relative abundance was compared in two populations of the temperate lizard Psammodromus algirus separated by 700 m altitude in central Spain. Habitat thermal quality was estimated with an index of how closely the available operative temperatures in a habitat match the range of body temperatures that lizards attempt to maintain in a laboratory thermogradient (Hertz, Huey & Stevenson 1993). 3. Operative temperatures, measured using copper models, were higher at the lowland site, where a large proportion of readings fell within or above the preferred range, especially in the early morning. Thermal habitat quality was also higher at the low altitude site, with smaller absolute deviations from the preferred range throughout most of the morning hours. Moreover, lizard body temperatures, the accuracy of thermoregulation and the predicted running performance of lizards were somewhat higher at the lowland site, although differences were smaller than expected on the basis of operative temperatures. A log-linear analysis showed that lizard selectivity for basking sites was more pronounced at the thermally inferior montane site. Thus, the observed differences in the thermal quality of habitats appeared to influence the behaviour of lizards. 4. Nevertheless, the relative abundance of lizards, as estimated by repeated transect counts, was higher at the montane site. This unexpected result suggests that thermal constraints may not be the most important factor determining lizard population densities on a regional scale. Alternatively, food availability and/or predation pressure might have a greater impact on the overall quality of a habitat for temperate lizards.

Summary 1.We studied seasonal changes in the thermoregulatory behaviour of the lacertid lizard Psammodroums algirus in a Mediterranean evergreen forest. Body temperatures ( T b ), environmental operative temperatures ( T e ) and upper and lower limits of the selected thermal range ( T sel ) were lower in May than in July. 2. On average, mean deviations of T b from T sel (0·7 ° C in both seasons) were much smaller than those of T e (8·3 ° C in both seasons). Thus both the accuracy (average difference between T b and T sel ) and effectiveness (the extent to which T b are closer than T e to T sel ) of thermoregulation were high, and similar in both seasons. 3. However the thermoregulatory contribution of two distinct behavioural mechanisms varied markedly between seasons. Daily activity contributed significantly to the regulation of T b in May (when a population of T e thermometers matching lizard activity patterns would be, on average, 1·0 ° C closer to T sel than were randomly available T e ), but not in July (when such a population would be only 0·2 ° C closer to T sel than were randomly available T e ). The selection of sun-shade patches, the contribution of which was larger than that of daily activity in both seasons, was more important in July (when it produced a distribution of T e that would be, on average, 3·1 ° C closer to T sel than were randomly distributed T e ) than in May (when a population of thermometers matching the lizards' pattern of exposure to sunlight would be 1·3 ° C closer to T sel than were randomly available T e ). 4. These changes are discussed in the light of seasonal differences in the daily patterns of among-patch variation in T e . In spring, lizard activity was low in the early morning because even the selection of sunlit patches was of limited utility to attain T b within T sel ; in summer, lizards could remain active at midday, despite low overall thermal suitability, by selecting shaded patches. Thus the contribution of patch selection to thermoregulation was important in the early basking period of both seasons, and at summer midday hours. 5. Our data suggest that shuttling between sun and shade, rather than selecting sun or shade, may be an additional mechanism of behavioural thermoregulation, the importance of which would be greatest at times of day when lizards use patches at random (e.g. spring midday hours), and that their mean T b is closer to the grand mean of full sun and full shade T e than to the mean equilibrium T e within any type of patch.

The influence of Pr ion on the structural and dielectric properties was studied in Sr1−xPrxTiO3 for 0<x<0.075 composition from room temperature to 375°C. X-ray diffraction and x-ray photoelectron spectroscopy studies revealed that the praseodymium ion enters substitutionally in the Sr site with mixed valence in a Pr+3∕Pr+4=2:1 ratio. This substitution yields compressive chemical pressure in the lattice. The polarization measurements at room temperature display hysteresis loops, indicating that the Pr ion induces ferroelectric behavior at room temperature. The permittivity shows a well-defined peak at about 240°C, indicative of a ferroelectric-paraelectric transition with Curie temperature of ∼118°C.

We studied the distribution of a common Mediterranean lacertid lizard, Psammodromus algirus (L.) 1758, on nineteen sites within a regional gradient of homogeneous yet contrasted habitats. This scale was large enough to allow line-transect estimates of lizard abundance, which were related to quantitative (and when possible multivariate) measurements of the structure and floristic composition of vegetation, the abundance of arthropod prey, the relative density of other lizard species, and the climatic data obtained from nearby meteorological stations. Neither the climate not the abundance of other lizards seemed to condition the quantitative distribution of the species. The positive influence of broad-leaved forests on the abundance of P. algirus appeared to be a consequence of structure attributes

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Body temperatures, heat exchange rates, behavioral thermoregulation, and movement behavior (as an index of foraging mode) were studied in two widely distributed medium—sized lacertid lizards (Acanthodasctylus erythrurus and Psammodromus algirus). P. algirus mainly inhabits broad—leaved forests, whereas A. erythrurus prefers open, sandy areas with sparsely distributed vegetation. These habitat preferences parallel differences between the areas in which both genera presumably originated: Eurosaharian xeric steppes with high operative temperatures (Te) for Acanthodacylus, and Mediterranean open Forest with lower Te for Psammodromus. Field observations showed that percentage of time spent basking and basking rate (number of basks per minute) were negatively related to Te, although average bask duration was not. Percentage of time spent moving, moving rate (number of moves per minute), and the average duration of individual moves were inversely related to Te and were higher in P. algirus. The percentage of total locomotion time that was spent moving in the shade was also higher in P. algirus. Behavioral thermoregulation strategies differed in laboratory thermogradient, where P. algirus basked more often and for shorter periods and selected warmer patches than did A. erythrurus. Selected body temperatures (Tb) in a laboratory thermogradient were significantly higher in A. erythrurus than in P. algirus. Shade Seeking Tb was higher in A. erythrurus, but Resume Basking Tb did not differ significantly between the two species. Heating and cooling rates also differed in the two species: A. erythrurus warmed more slowly and cooled faster than did P. algirus. Our data support the existence of a complex syndrome that combines aspects of the behavior, physiology, and ecology of both species. The thermal consequences of inhabiting a certain type of habitat can be counterbalanced by behavioral and physiological means that, in turn, affect movement and, hence, foraigng behavior. Thus, the more active species (P. algirus) heated faster, cooled more slowly, and basked more often but for shorter periods and at warmer patches than thee less active species (A. Erythrurus).