Low-intensity management benefits solitary bees in olive groves

One of the current challenges for applied ecologists is to understand how to manage/restore agroecosystems in a sustainable and cost-effective way. The intermediate landscape complexity hypothesis (ILCH) predicts that the effectiveness of agri-environmental measures (AES) on biodiversity and ecosystem services recovery is often largest in landscapes of intermediate complexity. This hypothesis has rarely been tested in savanna-like permanent agroecosystems. Focusing on pollinators, we test the ILCH at the regional scale in Mediterranean olive orchards, one of the most important permanent agroecosystems in the world. We inferred abundance of cavity-nesting pollinators in 40 paired olive orchards (extensively vs. intensively managed herbaceous cover) in 20 localities selected across a landscape complexity gradient. We also studied how different magnitudes in local management switches may affect pollinators by considering organic and intensive fields as management extremes in olive orchards. We used 208 trap nests for solitary bees to measure colonization rates. Additionally, we conducted pollinator surveys to ascertain that colonization rate was a representative proxy for pollinator activity. Our results showed that (a) changes in colonization rates due to local herb cover management peaked at intermediate landscape complexity, with extensively managed fields rendering higher colonization rates. (b) Organic fields had higher colonization rates than their control farms regardless of landscape complexity. (c) There was a highly significant correlation between nest colonization rates and density of pollinators foraging on flowers, which suggests that colonization rate is a good estimator of pollinator activity. Policy implications. The maintenance of ground herb cover (main agri-environmental measure in olive orchards) is a cost-effective investment allowing recuperation of pollinators when targeting olive farms located in landscapes of intermediate complexity. Additionally, fostering organic farming (still minority in olive groves) for the conservation of solitary bees should be a priority for policymakers since its effects are beneficial in any landscape.Ministerio de Ciencia e Innovación. Grant Number: BES‐2016‐078736 Ministerio de Economía y Competitividad. Grant Number: CGL2015‐68963‐C2 European Commission. Grant Number: LIFE14 NAT/ES/00109

Landscape-moderated biodiversity effects of ground herb cover in olive groves: Implications for regional biodiversity conservation

Studies assessing the effect of extensive versus intensive agricultural practices and addressing how biodiversity patterns and the effectiveness of agri-environmental practices (AES) to recover biodiversity are moderated by the landscape complexity (LMB framework), underlie large-scale biodiversity conservation programs and policies in anthropogenic landscapes. Such studies are numerous with annual crops and grasslands yet infrequent in more complex and structurally stable arboreal croplands, where high capacity to retain biodiversity is expected. Here, we explore to what extent landscape complexity and extensification of agricultural practices enhance biodiversity in olive groves of Andalusia (southern Spain). We monitored birds, ants and herbs in paired olive farms (extensive versus intensive ground herb cover management) from 20 localities spread over Andalusia and along a landscape complexity gradient. For each biological group, we obtained gamma diversity (diversity at the olive farm level), beta diversity (between the productive and unproductive areas located within the olive farm) and infield alpha diversity (in the productive area within the olive farm). We tested for multi-diversity, and for each group separately, three major hypotheses of the LMB: the intermediate-landscape complexity, the dominance of beta diversity, and the landscape species pool hypotheses. These hypotheses were corroborated with multi-diversity, which was affected by intensification of weed management and landscape simplification, suffering a combined impact of 26% of gamma biodiversity loss. The effectiveness of extensification to recover biodiversity depended on the landscape context and peaked at intermediate-complexity landscapes. Beta multi-diversity and infield alpha-diversity increased with landscape complexity. Birds, ants and weeds responded differently but were negatively affected either by landscape simplification or by management intensification. Birds mirrored better than other groups the multi-diversity pattern and were the best candidates for a rapid indicator of the impact of agriculture and land conversion on biodiversity. We provide recommendations for biodiversity conservation in olive groves-dominated landscapes and show that, if adequately managed, olive groves’ landscapes have potential for the conservation of biodiversity in the Mediterranean region. Our results illustrate the need to reformulate the future EU-Common Agricultural Policy and particularly, to adapt AES to each landscape.This study was funded by the LIFE project OLIVARES VIVOS (LIFE14 NAT/ES/1001094) of the European Commission, the project CGL2015-68963-C2-1-R of the Ministerio de Economía y Competitividad (MINECO, Spain Government) and FEDER

A gain-of-function polymorphism controlling complex traits and fitness in nature

Identification of the causal genes that control complex trait variation remains challenging, limiting our appreciation of the evolutionary processes that influence polymorphisms in nature. We cloned a quantitative trait locus that controls plant defensive chemistry, damage by insect herbivores, survival, and reproduction in the natural environments where this polymorphism evolved. These ecological effects are driven by duplications in the BCMA (branched-chain methionine allocation) loci controlling this variation and by two selectively favored amino acid changes in the glucosinolate-biosynthetic cytochrome P450 proteins that they encode. These changes cause a gain of novel enzyme function, modulated by allelic differences in catalytic rate and gene copy number. Ecological interactions in diverse environments likely contribute to the widespread polymorphism of this biochemical function