Annual variation of adult survival of a south-temperate House Wren population in Argentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the south.Here,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival estimators.We found that the probability of adult survival decreased as the abundance of breeding adults increased.This density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.

A global consistent positive effect of urban green area size on bird richness

Background: Although the species-urban green area relationship (SARu) has been analyzed worldwide, the global consistency of its parameters, such as the fit and the slope of models, remains unexplored. Moreover,the SARu can be explained by 20 different models. Therefore, our objective was to evaluate which models provide a better explanation of SARus and, focusing on the power model,to evaluate the global heterogeneity in its fit and slope. Methods: We tested the performance of multiple statistical models in accounting for the way in which species richness increases with area, and examined whether variability in model form was associated with various methodological and environmental factors. Focusing on the power model, we analyzed the global heterogeneity in the fit and slope of the models through a meta-analysis. Results: Among 20 analyzed models, the linear model provided the best fit to the most datasets, was the top ranked model according to our efficiency criterion, and was the top overall ranked model.The Kobayashi and power models were the second and third overall ranked models, respectively.The number of green areas and the minimum number of species within a green area were the only significant variables explaining the variation in model form and performance, accounting for less than 10% of the variation. Based on the power model,there was a consistent overall fit (r2=0.50) and positive slope of 0.20 for the species richness increase with area worldwide.Conclusions:The good fit of the linear model to our SARu datasets contrasts with the non-linear SAR frequently found in true and non-urban habitat island systems;however, this finding may be a result of the small sample size of many SARu datasets. The overall power model slope of 0.20 suggests low levels of isolation among urban green patches, or alternatively that habitat specialist and area sensitive species have already been extirpated from urban green areas.

Evolutionary Genetics of Invasive Mammal Species Introduced in Argentina

Evolutionary genetics of invasive species has been unexplored in Argentina. Invasive alien species (IAS) have a wide geographical distribution, characteristic life cycles and great ability to adapt, establish and spread in a new environment. Recent advances in novel molecular technologies, the use of higher resolution genetic markers, and the research development on genetic variation of invasive species consolidated the importance of genetic aspects in the invasion process. Undoubtedly, the growing concern for the disturbances generated by invasive species on biodiversity and functioning of ecosystems was also determinant for the inclusion of the Invasion Biology within the broad field of Evolutionary Biology including relevant examples that address the evolutionary genetic aspects of biological invasions. Recent studies suggest that the invasion success of many species depends on their ability to respond to natural selection. Although the number of invasive species registered in Argentina far exceeds 600, little research has been done on invasive mammal species and only five of them were hitherto genetically analyzed. Presuming that invasion genetics is incorporated into the agenda of control and management organizations, it would allow integrating the ecological, genetic, and evolutionary biology aspects for knowledge of invasive species widely distributed in Argentina. The objective of this article is to highlight the importance of evaluating the genetic structure of invasive species for their management and to inform about the invasive species of mammals that were introduced in Argentina and have been or are being analyzed genetically.

Thermal biology and locomotor performance in Phymaturus calcogaster:are Patagonian lizards vulnerable to climate change?

Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature.In particular,niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions.Lizards of the genus Phymaturus are viviparous,mainly herbivorous,and inhabit only rock promontories in the steppe environments of Patagonia and the Andes.Herein,we examine the vulnerability of the southernmost Phymaturus species to global warming:the endemic Phymaturus calcogaster,which lives in a mesic environment in eastern Patagonia.We studied body temperatures in the field(T_(b)),preferred body temperatures in a thermogradient(T_(pref)),the operative(T_(e))and environmental temperatures,and the dependence of running performance on body temperature.P.calcogaster had a mean T_(b)(27.04℃)and a mean Te(31.15℃)both lower than their preferred temperature(T_(pref)=36.61℃)and the optimal temperature for running performance(T_(o)=37.13℃).Lizard activity seems to be restraint during the early afternoon due high environmental temperatures.However,both,the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming(IPCC report in 2018)would not threaten,but indeed enhance locomotor performance in this population.

Reproductive strategies in males of the world’s southernmost lizards

Reproductive and life history patterns in reptiles are tightly related to the environmental conditions,so male reproductive cycles have been historically characterized as continuous,for tropical lizards,or seasonal,for temperate lizards.However,males of Liolaemus and Phymaturus lizards(Liolaemidae),from cold temperate climates of high altitudes or latitudes in Argentina and Chile,have developed a variety of reproductive cycles to coordinate with the short female reproductive season and to deal with the low frequency of reproductive females in the population.Using gonadal histology and morphological analysis,we describe the male reproductive biology,fat storage and sexual dimorphism of the viviparous lizards Liolaemus sarmientoi and Liolaemus magellanicus that inhabit an austral grass steppe at 51°S,in the southern limit of the American continent.Males of L.sarmientoi and L.magellanicus are reproductively available during the entire activity season of approximately 5 months.In addition,males of both species exhibit greater body sizes than females in morphological variables relevant in sexual selection.Meanwhile,females of both species exhibit larger inter-limb length than conspecific males,which suggests fecundity selection to increase space for a larger litter size.The continuous sperm production throughout the activity season allows these liolaemids to mate at any time when females ovulate,representing a selective advantage to deal with the short activity season and the adversities of the cold environment they inhabit.

Soil fertilization does not alter plant architectural effects on arthropod communities

Aims While a growing number of studies have demonstrated the impor-tance of intraspecific differences within plant species on associ-ated arthropod communities,little is known regarding the relative strength of these effects compared to environmental factors.In this study,we examined whether intraspecific plant differences and nutrient fertilization interact to shape the arthropod community of a dominant coastal shrub,Baccharis pilularis(coyote bush).Methods We overlaid a fertilization treatment on a 12-year-old common garden experiment planted with erect and prostrate architectural morphs of Baccharis in california,USA.to collect the associated arthropod community,we vacuum sampled the crown of each Baccharis and identified individuals to species or morphospecies.Important Findings We found that arthropod richness and abundance were 2-to 3-fold greater on prostrate Baccharis than on erect morphs,but observed no main effects of fertilizer addition on the over-all arthropod communities.Predators responded as strongly as herbivores to plant morph,and both were unaffected by nutrient additions.Only the specialist stem galler,Gnorimoschema bac-charisella,showed an interactive response to plant morph and fertilization.Nitrogen,phosphorous and potassium addition had opposite effects on the two morphs,increasing stem gall abun-dance by 50%on prostrate morphs,but reducing galling by 20%on erect morphs.the architectural complexity of prostrate morphs could be the driving mechanism of differences in arthropod assemblages.Overall,our results demonstrate that communitylevel consequences of intraspecific differences in plants are strong,rather than being context dependent,and are generally maintained under different resource environments.the growing number of studies showing strong genotype than nutrient effects on associated arthropod communities suggests that this might be a generalized pattern.