BUSCADOR RECOLECTA

Despite growing interest in the evolution of enlarged brains, the biological significance of brain size variation remains controversial. Much of the controversy is over the extent to which brain structures have evolved independently of each other (mosaic evolution) or in a coordinated way (concerted evolution). If larger brains have evolved by the increase of different brain regions in different species, it follows that comparisons of the whole brain might be biologically meaningless. Such an argument has been used to criticize comparative attempts to explain the existing variation in whole-brain size among species. Here, we show that pallium areas associated with domain-general cognition represent a large fraction of the entire brain, are disproportionally larger in large-brained birds and accurately predict variation in the whole brain when allometric effects are appropriately accounted for. While this does not question the importance of mosaic evolution, it suggests that examining specialized, small areas of the brain is not very helpful for understanding why some birds have evolved such large brains. Instead, the size of the whole brain reflects consistent variation in associative pallium areas and hence is functionally meaningful for comparative analyses.

Despite the recognised conservation value of phylogenetic diversity, little is known about how it is affected by the urbanisation process. Combining a complete avian phylogeny with surveys along urbanisation gradients from five continents, we show that highly urbanised environments supported on average 450 million fewer years of evolutionary history than the surrounding natural environments. This loss was primarily caused by species loss and could have been higher had not been partially compensated by the addition of urban exploiters and some exotic species. Highly urbanised environments also supported fewer evolutionary distinctive species, implying a disproportionate loss of evolutionary history. Compared with highly urbanised environments, changes in phylogenetic richness and evolutionary distinctiveness were less substantial in moderately urbanised environments. Protecting pristine environments is therefore essential for maintaining phylogenetic diversity, but moderate levels of urbanisation still preserve much of the original diversity.

Environmental variability has long been postulated as a major selective force in the evolution of large brains. However, assembling evidence for this hypothesis has proved difficult. Here, by combining brain size information for over 1,200 bird species with remote-sensing analyses a to estimate temporal variation in ecosystem productivity, we show that larger brains (relative to body size) are more likely to occur in species exposed to larger environmental variation throughout their geographic range. Our reconstructions of evolutionary trajectories are consistent with the hypothesis that larger brains (relative to body size) evolved when the species invaded more seasonal Regions. However, the alternative-that the species already possessed larger brains when they invaded more seasonal regions-cannot be completely ruled out. Regardless of the exact mechanism, our findings provide strong empirical support for the association between large brains and environmental variability.

Theory and evidence suggest that some selective pressures are more common on islands than in adjacent mainland habitats, leading evolution to follow predictable trends. The existence of predictable evolutionary trends has nonetheless been difficult to demonstrate, mainly because of the challenge of separating in situ evolution from sorting processes derived from colonization events. Here we use brain size measurements of >1900 avian species to reveal the existence of one such trend: increased brain size in island dwellers. Based on sister-taxa comparisons and phylogenetic ancestral trait estimations, we show that species living on islands have relatively larger brains than their mainland relatives and that these differences mainly reflect in situ evolution rather than varying colonization success. Our findings reinforce the view that in some instances evolution may be predictable, and yield insight into why some animals evolve larger brains despite substantial energetic and developmental costs.

When it comes to the brain, bigger is generally considered better in terms of cognitive performance. While this notion is supported by studies of birds and primates showing that larger brains improve learning capacity, similar evidence is surprisingly lacking for invertebrates. Although the brain of invertebrates is smaller and simpler than that of vertebrates, recent work in insects has revealed enormous variation in size across species. Here, we ask whether bee species that have larger brains also have higher learning abilities. We conducted an experiment in which field-collected individuals had to associate an unconditioned stimulus (sucrose) with a conditioned stimulus (coloured strip). We found that most species can learn to associate a colour with a reward, yet some do so better than others. These differences in learning were related to brain size: species with larger brains-both absolute and relative to body size-exhibited enhanced performance to learn the reward-colour association. Our finding highlights the functional significance of brain size in insects, filling a major gap in our understanding of brain evolution and opening new opportunities for future research.

Animal personality has become a major topic in animal behaviour. Much recent progress has come from the use of the open-field test, which is routinely used to separate individuals into fast and slow explorers. However, there is no standard way to conduct the test and it is unclear whether the test really measures exploration. Here, we addressed these issues by combining an open-field test with a battery of independent assays intended to assess the convergent and discriminant validity of the behavioural traits suggested to measure exploration in the open-field test. Our study subjects were common mynas, Acridotheres tristis, introduced to Australia. The analyses confirmed that the open-field test allows individuals to be separated according to their propensity to explore, mainly through metrics related to spatial and object examination of the novel cage. However, other metrics classically used to describe exploratory behaviour, such as the latency to enter the novel space, reflected shyness rather than exploration. The open-field test can therefore be a powerful tool to investigate personality, but only if the biological meanings of the metrics derived from the test are properly validated with independent behavioural assays., This work was supported by a Proyecto de Investigación (ref. CGL2013-47448-P) and a DURSI travel grant to D.S.

Despite the recognised conservation value of phylogenetic diversity, little is known about how it is affected by the urbanisation process. Combining a complete avian phylogeny with surveys along urbanisation gradients from five continents, we show that highly urbanised environments supported on average 450 million fewer years of evolutionary history than the surrounding natural environments. This loss was primarily caused by species loss and could have been higher had not been partially compensated by the addition of urban exploiters and some exotic species. Highly urbanised environments also supported fewer evolutionary distinctive species, implying a disproportionate loss of evolutionary history. Compared with highly urbanised environments, changes in phylogenetic richness and evolutionary distinctiveness were less substantial in moderately urbanised environments. Protecting pristine environments is therefore essential for maintaining phylogenetic diversity, but moderate levels of urbanisation still preserve much of the original diversity., This paper is part of the project CGL2013‐47448‐P from the Spanish Government to DS and IB. CG‐L was supported by the grant PUC1203 MECESUP‐Pontifica Universidad Católica de Chile.

Despite growing appreciation of the importance of considering a pace-of-life syndrome (POLS) perspective to understand how animals interact with their environment, studies relating behavior to life history under altered environmental conditions are still rare. By means of a comparative analysis of flight initiation distances (i.e., the distance at which an animal takes flight when a human being is approaching) across > 300 bird species distributed worldwide, we document here the existence of a POLS predicted by theory where slow-lived species tend to be more risk-averse than fast-lived species. This syndrome largely emerges from the influence of body mass, and is highly dependent on the environmental context. Accordingly, the POLS structure vanishes in urbanized environments due to slow-lived species adjusting their flight distances based on the perception of risk. While it is unclear whether changes in POLS reflect plastic and/or evolutionary adjustments, our findings highlight the need to integrate behavior into life history theory to fully understand how animals tolerate human-induced environmental changes., [Significance statement] Animals can often respond to changing environmental conditions by adjusting their behavior. However, the degree to which different species can modify their behavior depends on their life history strategy and on the environmental context. Species-specific perception of risk is a conspicuous example of adjustable behavior tightly associated with life history strategy. While there is a general tendency of higher risk aversion in rural than city-dwelling birds, it is dependent on the species’ life history strategy. Slow-lived species are more prone to adjust their flight initiation distances based on the perception of risk, allowing humans to approach closer in urban than rural environments. Behavior must therefore be taken into account together with life history to reliably assess species’ vulnerability at the face of ongoing environmental change., DS was supported by the project CGL2013-47448-P from the Spanish Government, AGV by project 2013–4834 from the Swedish Research Council and project IA201716 from PAPIIT, UNAM, IMC by the Fonds de Recherches du Quebec—Nature et Technologies (FQRNT) programme and by Harvard University, and LZG was supported by funds from The Ministry of Economy and Competitiveness (Spain) (CGL2015-70639-P) and The National Research, Development and Innovation Office (Hungary) (K-115970).

Aim: Habitat loss and alteration are widely considered one of the main drivers of current pollinator diversity loss. Yet little is known about habitat importance and preferences for major groups of pollinators, although this information is crucial to anticipate and mitigate the current decline of their populations. We aim to rank and assess the importance of different habitats for bees, to determine the preference for and avoidance of particular habitat types by different bees and to quantify the diversity of bees within and among habitats. Location: North-eastern USA. Time period: The sampling was done over 15 years (2001–2015). Major taxa studied: Apoidea. Methods: We used an unprecedented extensive dataset of >15,000 bee specimens, comprising more than 400 species collected across north-east USA. We extracted habitat information from the sample points and used network analyses, null models comparisons and beta-diversity analysis to assess habitat importance, habitat preference, use and diversity. Results: We found that natural habitats sustain higher bee diversity and a different set of species than agricultural and urban areas. Although many bee species used human-altered habitats, most species exhibited strong preferences for forested habitats and only a few preferred altered habitats over more natural habitats. In contrast to previous studies, landscape composition only had moderate buffer effects on diversity loss. The loss of biodiversity in human-altered environments could have been higher but it was partially compensated by the presence of human commensals and exotic species. Main conclusions: Although human-altered environments may harbour a substantial number of species, our work suggests that preserving natural areas is still essential to guarantee the conservation of bee biodiversity.

When it comes to the brain, bigger is generally considered
better in terms of cognitive performance. While this notion is
supported by studies of birds and primates showing that
larger brains improve learning capacity, similar evidence is
surprisingly lacking for invertebrates. Although the brain of
invertebrates is smaller and simpler than that of vertebrates,
recent work in insects has revealed enormous variation in
size across species. Here, we ask whether bee species that
have larger brains also have higher learning abilities. We
conducted an experiment in which field-collected individuals
had to associate an unconditioned stimulus (sucrose) with a
conditioned stimulus (coloured strip). We found that most
species can learn to associate a colour with a reward, yet
some do so better than others. These differences in learning
were related to brain size: species with larger brains—both
absolute and relative to body size—exhibited enhanced
performance to learn the reward-colour association. Our
finding highlights the functional significance of brain size in
insects, filling a major gap in our understanding of brain
evolution and opening new opportunities for future research, Peer reviewed

[Methods] We gathered presence/absence and abundance data from published studies and reports to characterize avian assemblages. The survey method varied across studies, but the same method was used for each habitat within a particular region, making data comparable using appropriate models., We gathered presence/absence and abundance data from published studies and reports for 319 well-characterized assemblages spanning 50 cities from Africa, Australia, Europe, North America and South America. We focused on cities with comparable survey data within urban habitats and in nearby natural habitat. The final dataset contains almost 10,000 records for 1507bird species, 66 of which are introduced (non-native) in at least one study region. Species abundance per unit area or unit time were available for 269 assemblages from 42 cities, comprising 1353 species. Following Newbold et al. (2015), we used published habitat descriptions to classify the intensity of human use in urban habitats for each assemblage: (1) highly urbanised environments mainly contain densely packed buildings with vegetation scarce or absent; (2) moderately urbanised environments are residential areas with single-family houses and associated gardens; and (3) little-urbanised environments have few buildings and abundant vegetation (e.g. urban parks). The habitats outside the city were assigned to either natural vegetation or rural habitat based on the description of the habitat given in the source paper. Standardised survey methods were used across habitats within each region., Ministerio de Ciencia e Innovación, Award: CGL2013-47448-P. ANID-FONDECYT., Peer reviewed