Shrike predation on the lizard Mesalina adramitana in Qatar; a review of reported reptile and amphibian prey

We report, for the first time, evidence of predation by a shrike (Lanius sp.) on the lizard Mesalina adramitana. This is the first record of predation by shrikes on lizards in Qatar. Whilst we did not directly observe the event, the presence of shrikes in the area and the method of impalement indicate shrikes as the predator. The lizard was found freshly impaled on a palm tree (Phoenix dactylifera), at 150 cm above ground. Bird species of the genus Lanius are well-known predators of lizards, and in arid environments reptiles are likely common prey for these birds. We provide a review of literature concerning predatory events by shrikes on reptiles and amphibians. We suggest inspection of shrubs for animals impaled by shrikes can improve biodiversity inventories, complementing other commonly used methods

Reproductive variation of the lizard Xenosaurus platyceps: comparing two populations of contrasting environments

We studied litter size, size at birth, and relative litter mass (RLM) in two populations of the crevice-dwelling lizard Xenosaurus platyceps: one located in a low-altitude tropical forest; and the other in a high-altitude temperate oak forest. We found a significant relationship between female size and litter size. Females from the temperate site produced significantly larger litters in comparison with those from the tropical site after adjusting for female size. Neither a relationship between female size and offspring size nor a difference between populations in offspring size was detected, which suggests that this trait could be either constrained or optimized. RLM showed the same pattern as litter size: Larger females exhibited greater RLM, and this trait showed significantly larger values in the temperate locality. This pattern is explained by evidence that females in the temperate population are producing more young of similar size than those produced by their tropical counterparts. We did not find significant interannual variation in any of the reproductive traits studied. We suggest reciprocal transplant or common garden experiments to determine the genetic and proximal causes of the observed intraspecific variation

analysis of the population dynamics of an endangered lizard (xenosaurus grandis) through the use of projection matrices

We conducted a demographic analysis from 2000 to 2004 of a population of the crevice-dwelling lizard, Xenosaurus grandis, in Veracruz, Mexico. We used population projection matrices to model its population dynamics. Three of the four annual matrices projected an actively growing population, whereas the matrix corresponding to 2003-2004 projected a declining population, apparently associated with a higher-than-average environmental temperature during this period. Observed population structure differed from that expected at equilibrium, according to the four matrices. Highest reproductive values corresponded to adult categories. The transition of newborns and juveniles to larger categories, as well as adult stasis, were the vital rates that made the largest contribution to population growth rate (lambda). Growth from one size class to the next was the demographic process that contributed the most to lambda, and all size classes had similar elasticities in all years. Stochastic simulations integrating interannual demographic variability projected population growth rates above unity, even under an ecological scenario that consisted of 50% of unfavorable years. Despite this trend toward positive population growth, this X. grandis population faces an imminent threat due to the growing industrial development in the region in which it is endemic. Thus, we suggest this population as a primary target for conservation efforts, as well as a change in the conservation category of this species from "special protection" to "threatened.

Demography of Xenosaurus platyceps (Squamata: Xenosauridae): a comparison between tropical and temperate populations

There appears to be variation in life-history strategies even between populations of the same species. For ectothermic organisms such as lizards, it has been predicted that demographic and life-history traits should differ consistently between temperate and tropical populations. This study compares the demographic strategies of a temperate and a tropical population of the lizard Xenosaurus platyceps. Population growth rates in both types of environments indicated populations in numerical equilibrium. Of the two populations, we found that the temperate population experiences lower adult mortality. The relative importance (estimated as the relative contribution to population growth rate) of permanence and of the adult/reproductive size classes is higher in the temperate population. In contrast, the relative importance for average fitness of fecundity and growth is higher in the tropical population. These results are consistent with the theoretical frameworks about life-historical differences among tropical and temperate lizard populations

Lizard antipredatory behaviours preventing extraction from crevaces.

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Synopsis and taxonomic revision of three genera in the snake tribe Sonorini

Cox, Christian L., Davis Rabosky, Alison R., Holmes, Iris A., Reyes-Velasco, Jacobo, Roelke, Corey E., Smith, Eric N., Flores-Villela, Oscar, McGuire, Jimmy A., Campbell, Jonathan A. (2018): Synopsis and taxonomic revision of three genera in the snake tribe Sonorini. Journal of Natural History 52 (13-16): 945-988, DOI: 10.1080/00222933.2018.1449912, URL: http://dx.doi.org/10.1080/00222933.2018.144991