Social-ecological cascade effects of land use on vertebrate pest dynamics in arid agricultural communities.

Extensive land conversion to agriculture in drylands and associated resource use have wide-ranging impacts on desert ecosystems globally. Incorporating the impacts of human-social aspects is thus imperative in examining ecological interactions. The provision of agricultural inputs in these resource-scarce regions supports invasive and pest species, negatively impacting both agricultural productivity and native desert ecosystems. Understanding the spatial dynamics of invasive and pest species requires analyzing both bottom-up resource availability factors underlying animal distributions and top-down biological controls. Here, we evaluate the social-ecological cascading effects of dryland agriculture on vertebrate pest communities in dryland agricultural communities of Israel. Our study region is characterized by 18 agricultural cooperatives with distinct crop regimes due to contrasting social decision-making and resource allocation schemes (i.e., communal kibbutzim vs. privatized moshavim). Crop choices further affect land management (e.g., enclosed vs. open farm systems) and resource intensity. This system is ideal for studying trophic mechanisms underlying animal assemblages between agricultural regimes. We examine the role of agricultural land-use practices on pest spatial distributions based on multiyear vertebrate pest observations with agricultural data sets. We use structural equation modeling (SEM) to quantify the relative importance of added agricultural resources underlying bottom-up and top-down trophic processes regulating vertebrate pest assemblages. Results reveal that crop choices determine pest distributions through bottom-up processes directly, while simultaneously driving pest competitive interactions through indirect top-down cascades impacting pest communities. For example, due to the indirect negative effect of wolves on mesopredators (foxes and jackals) mediated by livestock, the total positive effect of livestock on the abundance of mesopredators is reduced. Our study illustrates the social-ecological cascading effects of agricultural regimes on pest community assemblages mediated by contrasting agricultural land-use practices. Considering the expansion of dryland agroecological systems globally, understanding the intricate cascading pathways of predator- and prey-pest communities has important implications for agricultural management, biological invasions in drylands, and fragile desert environments.

Global evaluation of current and future threats to drylands and their vertebrate biodiversity.

Drylands are often overlooked in broad conservation frameworks and development priorities and face increasing threats from human activities. Here we evaluated the formal degree of protection of global drylands, their land vertebrate biodiversity and current threats, and projected human-induced land-use changes to drylands under different future climate change and socioeconomic scenarios. Overall, drylands have lower protected-area coverage (12%) compared to non-drylands (21%). Consequently, most dryland vertebrates including many endemic and narrow-ranging species are inadequately protected (0-2% range coverage). Dryland vertebrates are threatened by varied anthropogenic factors-including agricultural and infrastructure development (that is, artificial structures, surfaces, roads and industrial sites). Alarmingly, by 2100 drylands are projected to experience some degree of land conversion in 95-100% of their current natural habitat due to urban, agricultural and alternative energy expansion. This loss of undisturbed dryland regions is expected across different socioeconomic pathways, even under optimistic scenarios characterized by progressive climate policies and moderate socioeconomic trends.

The effect of capture-and-handling stress on carotenoid-based beak coloration in zebra finches.

Stress can have widespread effects on animal behaviors and phenotypes, including sexually selected traits. Ornamental colors have long been studied as honest signals of condition, but few studies have been conducted on how the physiological stress response (i.e., corticosterone (CORT) elevation) impacts color expression. We used a traditional capture-and-restraint technique to examine the effect of repeated handling stress on carotenoid-dependent beak coloration in male and female zebra finches (Taeniopygia guttata). Birds subjected to daily, 10-min handling treatments, which elevated circulating CORT levels, for a four-week period displayed deeper orange/red beak coloration than did control animals. Stressed males lost body mass during the experiment and marginally decreased in circulating carotenoid concentrations. Hence, handling stress may have reduced food intake or induced mobilization of body stores (i.e., fat) of carotenoids. In contrast to males, stressed females maintained orange beak color, while control females faded in color. This study highlights sex- and pigment-specific mechanisms by which stress may temporarily enhance the expression of sexual traits, but at the expense of other key fitness traits (e.g., body mass maintenance, reproduction).

Publisher Correction: The global distribution of tetrapods reveals a need for targeted reptile conservation.

In this Article originally published, owing to a technical error, the author 'Laurent Chirio' was mistakenly designated as a corresponding author in the HTML version, the PDF was correct. This error has now been corrected in the HTML version. Further, in Supplementary Table 3, the authors misspelt the surname of 'Danny Meirte'; this file has now been replaced.

The global distribution of tetrapods reveals a need for targeted reptile conservation.

The distributions of amphibians, birds and mammals have underpinned global and local conservation priorities, and have been fundamental to our understanding of the determinants of global biodiversity. In contrast, the global distributions of reptiles, representing a third of terrestrial vertebrate diversity, have been unavailable. This prevented the incorporation of reptiles into conservation planning and biased our understanding of the underlying processes governing global vertebrate biodiversity. Here, we present and analyse the global distribution of 10,064 reptile species (99% of extant terrestrial species). We show that richness patterns of the other three tetrapod classes are good spatial surrogates for species richness of all reptiles combined and of snakes, but characterize diversity patterns of lizards and turtles poorly. Hotspots of total and endemic lizard richness overlap very little with those of other taxa. Moreover, existing protected areas, sites of biodiversity significance and global conservation schemes represent birds and mammals better than reptiles. We show that additional conservation actions are needed to effectively protect reptiles, particularly lizards and turtles. Adding reptile knowledge to a global complementarity conservation priority scheme identifies many locations that consequently become important. Notably, investing resources in some of the world's arid, grassland and savannah habitats might be necessary to represent all terrestrial vertebrates efficiently.