Lizard activity and endurance of cold climate is regulated by several factors such as evolutionary potential, acclimatization capacity, physiological tolerance, and locomotion among thermally advantageous microenvironments. Liolaemus lineomaculatus, a lizard inhabiting a wide range of cold environments in Patagonia, provides an excellent model to test interpopulation variability in thermal performance curves (TPCs) and usage of microhabitats. We obtained critical thermal minima and maxima, and performed running trials at eight temperatures using lizards from both a temperate-site (high-altitude) population at 42° S and a cold-site population at 50° S. The availability of environmental temperatures for running performance in open ground and in potential lizard refuges were recorded, and showed that lizards in the temperate site had a greater availability of thermal environments offering temperatures conducive to locomotion. Generalized additive mixed models showed that the two populations displayed TPCs of different shapes in 0.15 m runs at temperatures near their optimal temperature, indicating a difference in thermal sensitivity at high temperatures. However, the rest of the locomotor parameters remained similar between Liolaemus lineomaculatus from thermal and ecological extremes of their geographic distribution and this may partly explain their ability to endure a cold climate.

In environments where the temperature periodically drops below zero, it is remarkable that some lizards can survive. Behaviorally, lizards can find microsites for overwintering where temperatures do not drop as much as the air temperature. Physiologically, they can alter their biochemical balance to tolerate freezing or avoid it by supercooling. We evaluated the cold hardiness of a population of Liolaemus pictus argentinus Müller and Hellmich, 1939 in the mountains of Esquel (Patagonia, Argentina) during autumn. Additionally, we assessed the thermal quality (in degree-days) of potential refuges in a mid-elevation forest (1100 m above sea level (asl)) and in the high Andean steppe (1400 m asl). We analyzed the role of urea, glucose, total proteins, and albumin as possible cryoprotectants, comparing a group of lizards gradually exposed to temperatures lower than 0 °C with a control group maintained at room temperature. However, we found no evidence to support the presence of freeze tolerance or supercooling mechanisms in this species as related to the analyzed metabolites. Instead, the low frequency of degree-days below 0 °C and temperatures never lower than −3 °C in potential refuges suggest that L. p. argentinus might avoid physiological investments (such as supercooling and freeze tolerance) by behaviorally selecting appropriate refuges to overcome cold environmental temperatures.

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Adequate pollination is fundamental to optimize reproduction and yield of most flowering plants, including many staple food crops. Plants depending on insect pollination rely heavily on many wild species of solitary and social bees, and declines or absence of bees often hampers crop productivity, prompting supplementation of pollination services with managed bees. Though honeybees are the most widely deployed managed pollinators, many high-value crops are pollinated more efficiently by bumblebees (Bombus spp.), prompting domestication and commercial rearing of several species. This led to a blooming international trade that translocated species outside their native range, where they escaped management and invaded the ecosystems around their deployment sites. Here, we briefly review the history of bumblebee invasions and their main impacts on invaded ecosystems, and close by discussing alternatives to the use of commercially reared bumblebees to enhance crop pollination. As evidence of widespread negative effects on local ecosystems of bumblebee invasions builds up, bumblebee trade adds to the list of examples of "biological" strategies devised to solve agricultural problems that ended up being far from the "green," eco-friendly solutions they were expected to be.

RESUMEN.Dado el rol fundamental de los artrópodos y los insectos en el funcionamiento de los ecosistemas áridos, para manejar estos ambientes resulta necesario conocer su relación con las características de la vegetación local. Dentro de la región fitogeográfica del Chaco, en Los Llanos de la provincia de La Rioja, Argentina, existen grandes cambios en la vegetación en distancias cortas, lo que determina un gradiente de heterogeneidad vegetal. El objetivo de este estudio fue analizar la respuesta de los artrópodos epígeos a estos cambios. En este gradiente se seleccionaron 3 ambientes (Salinas, Interfaz y Monte) en los que se recolectaron artrópodos y, dentro de éstos, insectos mediante trampas de caída durante 7 días en la temporada cálida. Se determinó la abundancia total de artrópodos e insectos y la riqueza de especies/morfoespecies de insectos. Se evaluó la asociación entre los ambientes y la abundancia y riqueza de especies mediante un ANOVA de medidas repetidas. Para evaluar la completitud del muestreo se utilizaron estimadores de riqueza no-paramétricos (Chao 1 , Jackniffe 1 y Bootstrap) y curvas de acumulación de especies. Para evaluar la estructura de la comunidad se usaron curvas de rango-abundancia y análisis multivariados. Se recolectaron en total 8380 artrópodos, de los cuales 5902 fueron insectos que se agruparon en 14 órdenes, 31 superfamilias, 35 familias y 114 especies/morfoespecies. El ambiente con mayor heterogeneidad vegetal (Monte) presentó la mayor abundancia de artrópodos y la mayor abundancia y riqueza de insectos. Las familias de insectos más abundantes y de mayor riqueza fueron Formicidae (Hymenoptera) y Tenebrionidae (Coleoptera). Chao 1 y Bootstrap fueron los mejores estimadores de riqueza. En este estudio se encontró que la abundancia, la riqueza y la composición de especies de artrópodos, y particularmente insectos, estuvo asociada a un gradiente de vegetación.[Palabras clave: variabilidad, entomofauna epígea, indicadores, suelo, región chaqueña, La Rioja] ABSTRACT. Of arthropods and plants: Arthropod fauna diversity in a vegetation gradient in Los Llanos of La Rioja province (Argentina).Given the fundamental role of arthropods and insects in the functioning of arid ecosystems, it is of key importance to understand their relationships with the environment, particularly for the development of future conservation efforts. Within the phytogeographic region of Chaco, in Los Llanos (La Rioja province, Argentina), great changes in vegetation occur within short distances, determining a pronounced gradient of plant heterogeneity. The aim of this study was to analyse the response of epigaeic arthropods to these changes. In this gradient, three environments were selected (Salinas, Interface and Monte), in which we collected arthropods and insects using fall traps during seven days during the warm season. Total abundance of arthropods and insects, and richness of insect species/morpho-species were determined. The association between the environments and the abundance and richness of species wa...

In temperate, polar and montane environments, ectotherms must fi nd ways to endure throughout the coldest months of the year. Lizards search for microsites where temperatures remain warm or alter their biochemical balance to tolerate freezing or avoid it by supercooling. We evaluated the cold hardiness and potential winter refuges of two populations of Liolaemus lineomaculatus, from a temperate site (42°S) and a cold site (50°S). We analysed the role of possible cryoprotectants by comparing a group of cooled-down lizards with a control group of lizards that were not exposed to cold.The populations of this study are not freeze tolerant and the biochemical analysis showed no evidence of metabolites signifi cantly changing concentration after exposure to cold. However, the species remained several hours at their Supercooling Point (SCP), suggesting they can supercool. The analysis of potential winter refuges showed that lizards using these potential refuges would spend almost no time at all at temperatures close to or below their SCP. Furthermore, lizards from the cold site were able to survive below 0°C temperatures with a lower SCP than lizards from the temperate site. Liolaemus lineomaculatus developed physiological mechanisms that can help them survive when temperatures drop sharply, even when lizards are in suitable shelters.

Immature individuals move from their natal area to the area where they settle and reproduce, and this may take several years. This process is essential for long-lived species such as vultures and condors, which spend long periods as immature and move extensively. We studied the movement behavior of 26 GPS-tagged immature Andean condors (Vultur gryphus) from northwestern Patagonia throughout the immature stage, analyzing whether these patterns differed according to age, sex and season. We found that season and age influenced home range size and flight distances, the warm season being when immature condors move most; movement patterns were greater in sub-adults than in juveniles. The age effect was associated with the sex of individuals, with males increasing their home range more than females. Our results provide the first description of how immature Andean condor movement patterns are affected by internal and external factors. This information could be key to understanding condor responses to environmental change and threats at different stages during their immature phase. Until now, condor conservation efforts have not considered the areas used by dispersing individuals. Our results increase our understanding of ranging behavior during the immature stage of this threatened bird, enabling us to improve the conservation policies and management strategies designed to protect them.