Reproductive Biology of a Blue-tail Skinks(Plestiodon)Population from a Temperate Forest,East-central Puebla,México

We studied the cycles of reproduction and fat bodies of a blue-tailed skink population of an undescribed species of the Plestiodon brevirostris group.Sexual maturity is attained by females and males as they both reach about 59 mm of SVL.Vitellogenesis started in June-July,with ovulation occurring during late-October to mid-November,and parturition in mid-spring.Litter size varied from two to six,with a mean of 3.86±0.15 embryos in uterus,and showed a positive correlation with female body mass and SVL.During gestation,a significant increase in the average wet mass of embryos in uterus was evident.In comparison,there were no notable changes in the average dry mass.Juvenile growth data suggest that sexual maturity,both males and females,is reached at 16-17 months of age.Testicles and epididymides exhibited maximal weight during August-September.Testicular regression occurred in September.Mating apparently takes place from mid-summer to early fall.Lipids stored in female fat bodies are used for vitellogenesis and for nutrition during the winter months.In males,the stored lipids appear to be used in reproductive activities during the mating season.

Highly divergent sympatric lineages of Leptotila verreauxi(Aves:Columbidae)suggest a secondary contact area in the Isthmus of Tehuantepec,Mexico

Due to a complex geological and biotic history,the Isthmus of Tehuantepec(IT),has been long recognized as a driver for the evolutionary divergence of numerous lowland and highland taxa.Widely distributed in the lowlands of the American continent,the White-Tipped Dove(Leptotila verreauxi)is a polytypic species with 13 recognized subspecies.Four of these have been recorded in Mexico,and the distribution of three abuts at the IT,suggesting a contact zone.To estimate phylogenetic patterns,divergence times and genetic differentiation,we examined two mt DNA(ND2 and COI)and one n DNA(β-fibint 7)markers.We also used correlative ecological niche models(ENM)to assess whether ecological differences across the IT may have acted as a biogeographical boundary.We estimated paleodistributions during the Middle Holocene,Last Glacial Maximum and Last Interglacial,to evaluate the influence of climate changes on the distribution and demographic changes.Our results showed genetically distinct lineages that diverged approximately 2.5 million years ago.Climatic and ecological factors may have played a dual role in promoting differentiation,but also in the formation of a secondary contact zone in the southern IT.Our ecological niche comparisons indicated that the ecological niche of sympatric lineages at the IT are not identical,suggesting niches divergence;in addition,environmental niche models across the region indicated no abrupt biogeographic barriers,but the presence of regions with low suitability.These results suggest that genetic differentiation originated by a vicariant event probably related to environmental factors,favored the evolution of different ecological niches.Also,the absence of a biogeographic barrier but the presence of less suitable areas in the contact regions,suggest that secondary contact zones may be also maintained by climatic factors for the eastern group,but also by biotic interactions for the western group.

Phylogeography and morphometric variation in the Cinnamon Hummingbird complex:Amazilia rutila(Aves:Trochilidae)

Background:The Mesoamerican dominion is a biogeographic area of great interest due to its complex topography and distinctive climatic history.This area has a large diversity of habitats,including tropical deciduous forests,which house a large number of endemic species.Here,we assess phylogeographic pattern,genetic and morphometric variation in the Cinnamon Hummingbird complex Amazilia rutila,which prefers habitats in this region.This resident species is distributed along the Pacific coast from Sinaloa—including the Tres Marías Islands in Mexico to Costa Rica,and from the coastal plain of the Yucatán Peninsula of Mexico south to Belize.Methods:We obtained genetic data from 85 samples of A.rutila,using 4 different molecular markers(mtDNA:ND2,COI;nDNA:ODC,MUSK)on which we performed analyses of population structure(median-joining network,STRU CTU RE,FST,AMOVA),Bayesian and Maximum Likelihood phylogenetic analyses,and divergence time estimates.In order to evaluate the historic suitability of environmental conditions,we constructed projection models using past scenarios(Pleistocene periods),and conducted Bayesian Skyline Plots(BSP)to visualize changes in population sizes over time.To analyze morphometric variation,we took measurements of 5 morphological traits from 210 study skins.We tested for differences between sexes,differences among geographic groups(defined based on genetic results),and used PCA to examine the variation in multivariate space.Results:Using mtDNA,we recovered four main geographic groups:the Pacific coast,the Tres Marías Islands,the Chiapas region,and the Yucatán Peninsula together with Central America.These same groups were recovered by the phylogenetic results based on the multilocus dataset.Demography based on BSP results showed constant population size over time throughout the A.rutila complex and within each geographic group.Ecological niche model projec-tions onto past scenarios revealed no drastic changes in suitable conditions,but revealed some possible refuges.Mor-phometric results showed minor sexual dimorphism in this species and statistically significant differences between geographic groups.The Tres Marías Islands population was the most differentiated,having larger body size than the remaining groups.Conclusions:The best supported evolutionary hypothesis of diversification within this group corresponds to geo-graphic isolation(limited gene flow),differences in current environmental conditions,and historical habitat fragmen-tation promoted by past events(Pleistocene refugia).Four well-defined clades comprise the A.rutila complex,and we assess the importance of a taxonomic reevaluation.Our data suggest that both of A.r.graysoni(Tres Marías Islands)and A.r.rutila(Pacific coast)should be considered full species.The other two strongly supported clades are:(a)the Chiapas group(southern Mexico),and(b)the populations from Yucatán Peninsula and Central America.These clades belong to the corallirostris taxon,which needs to be split and properly named.