Agricultural landscapes as habitat for birds in central Chile

Background: Understanding the role of agroecosystems as habitat for wildlife is crucial for long-term conservation planning, as different crop stratification and landscape elements can influence bird communities, which are also affected by seasonality. The goal of our study was to determine how agricultural landscapes varying in land cover characteristics affect bird richness and abundance. Bird surveys were conducted at 110 locations within agricultural landscapes in central Chile. The surveyed areas were characterized by land cover at two scales (50 and 500 m radii) through direct observation and photo-interpretation, during winter and spring seasons. Generalized Linear Mixed Models were used to evaluate the effects of different agricultural land covers on bird species and communities. Results: Our results show that birds were more abundant during winter, in particular for insectivorous and granivorous birds, and that bird species richness was significantly increased due to cover provided by hedgerows at the plot scale. Conclusions: We found that abundance of some bird species in agroecosystems in central Chile was higher in winter than in spring, and that overall bird richness was favored by structural diversity including non-crop structures such as hedgerows, which thus may be relevant for improving bird conservation management in temperate agroecosystems. Our results suggest that native vegetation proximity and area may affect seasonal changes in bird communities at larger scales, relationships which warrant further study.Chilean Commission for Scientific and Technological Research (CONICYT) 2209010

On Reciprocal Causation in the Evolutionary Process

Recent calls for a revision of standard evolutionary theory (SET) are based partly on arguments about the reciprocal causation. Reciprocal causation means that cause–effect relationships are bi-directional, as a cause could later become an effect and vice versa. Such dynamic cause-effect relationships raise questions about the distinction between proximate and ultimate causes, as originally formulated by Ernst Mayr. They have also motivated some biologists and philosophers to argue for an Extended Evolutionary Synthesis (EES). The EES will supposedly expand the scope of the Modern Synthesis (MS) and SET, which has been characterized as gene-centred, relying primarily on natural selection and largely neglecting reciprocal causation. Here, I critically examine these claims, with a special focus on the last conjecture. I conclude that reciprocal causation has long been recognized as important by naturalists, ecologists and evolutionary biologists working in the in the MS tradition, although it it could be explored even further. Numerous empirical examples of reciprocal causation in the form of positive and negative feedback are now well known from both natural and laboratory systems. Reciprocal causation have also been explicitly incorporated in mathematical models of coevolutionary arms races, frequency-dependent selection, eco-evolutionary dynamics and sexual selection. Such dynamic feedback were already recognized by Richard Levins and Richard Lewontin in their bok The Dialectical Biologist. Reciprocal causation and dynamic feedback might also be one of the few contributions of dialectical thinking and Marxist philosophy in evolutionary theory. I discuss some promising empirical and analytical tools to study reciprocal causation and the implications for the EES. Finally, I briefly discuss how quantitative genetics can be adapated to studies of reciprocal causation, constructive inheritance and phenotypic plasticity and suggest that the flexibility of this approach might have been underestimated by critics of contemporary evolutionary biology

The Red Queen Process does not Select for High Recombination Rates in Haplodiploid Hosts

One of the main competing theories to describe the evolution of recombination is the Red Queen Hypothesis (RQH). Presently, many theoretical analyses of the RQH typically examine fitness interactions in host-parasite frameworks. Less emphasis has been placed on understanding the impact of host ploidy in these systems. In this study, we look to investigate the high observed rates of recombination observed in two common haplodiploid species (Apis mellifera and Bombus terrestris). We compared haplodiploid to diploid host populations under infection with haploid asexual parasites, using a Matching Allele (MAM) model. Results from a simulation analysis showed that the Red Queen does not run in haplodiploid hosts and is therefore, probably not responsible for the high recombination rates observed so far in haplodiploid hosts.Deutsche Forschungsgemeinschaft (DFG)as part of the SPP project number 1399.http://link.springer.com/journal/11692hb2013ab201

A STOCHASTIC MODEL FOR SPECIATION BY MATING PREFERENCES

International audienceMechanisms leading to speciation are a major focus in evolutionary biology. In this paper, we present and study a stochastic model of population where individuals, with type a or A, are equivalent from ecological, demographical and spatial points of view, and differ only by their mating preference: two individuals with the same genotype have a higher probability to mate and produce a viable offspring. The population is subdivided in several patches and individuals may migrate between them. We show that mating preferences by themselves, even if they are very small, are enough to entail reproductive isolation between patches, and we provide the time needed for this isolation to occur as a function of the carrying capacity. Our results rely on a fine study of the stochastic process and of its deterministic limit in large population, which is given by a system of coupled nonlinear differential equations. Besides, we propose several generalisations of our model, and prove that our findings are robust for those generalisations

Wild pollinators in arable habitats: trends, threats and opportunities

The dramatic declines in pollinator (social and solitary bees, wasps, flies, beetles, butterflies, and moths) abundance and diversity observed in Europe and globally in recent decades have generated widespread scientific and societal concern. It is particularly important to conserve healthy populations of pollinators in arable landscapes because of the ‘ecosystem service’ they provide to mass flowering crops such as field beans. Changes in land use prior to the 1970s led to declines in more specialist bee species that have now become rare or extinct in arable landscapes, being replaced by a more generalist, resilient pollinator community. Responses of pollinators to agricultural intensification since the 1970s are subtle and need to be interpreted in the context of other drivers including climate change and pathogen load. However, it is incontrovertible that agricultural practices such as the use of pesticides and loss of semi-natural habitat can have a detrimental effect on pollinator communities and the ecosystem service they provide. It is vital, therefore, that arable landscapes are managed in a way that provides sufficient resource and nesting habitat and either avoids or mitigates exposure to pesticides; the efficacy of specific measures to achieve this are reviewed

Functional plasticity in vertebrate scavenger assemblages in the presence of introduced competitors

Introduced species may suppress or enhance ecological functions, or they may have neutral effects in ecosystems where they replace or complement native species. Few studies, however, have explicitly tested for these trajectories, and for the effect these might have for native species. In this study, we experimentally test the trajectory and scale of change in the function of 'carrion removal' at different carrion loads along ocean beaches in Eastern Australia that have different numbers of introduced red foxes (Vulpes vulpes) and several species of native raptors. We hypothesized that the 'positive' effect of foxes on carrion removal would be greatest at high carrion loads, because competition for resources between native and introduced species is lower. Scavenger abundance, fox occurrences, and carrion consumption by these species differed widely between locations and times. Despite distinct spatial differences in the structure of vertebrate scavenger assemblages, total carrion consumption was not significantly different between locations at any carrion load. This lack of variation in functional rates indicates potential functional plasticity in the scavenger assemblage and possible functional accommodation of red foxes. Neutral fox effects on ecological functions or the ecosystem more broadly are, however, very unlikely to extend beyond carrion consumption