Loss of species and functions in a deforested megadiverse tropical forest.

Tropical species richness is threatened by habitat degradation associated with land-use conversion, yet the consequences for functional diversity remain little understood. Progress has been hindered by difficulties in obtaining comprehensive species-level trait information to characterize entire assemblages and insufficient appreciation that increasing land-cover heterogeneity potentially compensates for species loss. We examined the impacts of tropical deforestation associated with land-use heterogeneity on bird species richness, functional redundancy, functional diversity, and associated components (i.e., alpha diversity, species dissimilarity, and interaction strength of the relationship between abundance and functional dissimilarity). We analyzed over 200 georeferenced bird assemblages in the Atlantic Forest of Brazil. We characterized the functional role of the species of each assemblage and modeled biodiversity metrics as a function of forest cover and land-cover heterogeneity. Replacement of native Atlantic Forest with a mosaic of land uses (e.g., agriculture, pastures, and urbanization) reduced bird species richness in a nonrandom way. Core forest species, or species considered sensitive to edges, tended to be absent in communities in heterogenous environments. Overall, functional diversity and functional redundancy of bird species were not affected by forest loss. However, birds in highly heterogenous habitats were functionally distinct from birds in forest, suggesting a shift in community composition toward mosaic-exclusive species led by land-cover heterogeneity. Threatened species of the Atlantic Forest did not seem to tolerate degraded and heterogeneous environments; they remained primarily in areas with large forest tracts. Our results shed light on the complex effects of native forest transformation to mosaics of anthropogenic landscapes and emphasize the importance of considering the effects of deforestation and land-use heterogeneity when assessing deforestation effects on Neotropical biodiversity.

Pérdida de especies y funciones en un bosque tropical megadiverso deforestado Resumen La riqueza de especies tropicales está amenazada por la degradación asociada con la conversión del uso de suelo, y aun así entendemos muy poco de las consecuencias que esto tiene para la diversidad funcional. El progreso está obstaculizado por las dificultades para obtener información completa de los rasgos a nivel de especie para caracterizar ensamblajes completos y la apreciación insuficiente de que la heterogeneidad creciente de la cobertura del suelo tiene el potencial para compensar la pérdida de especies. Analizamos el impacto que tiene la deforestación tropical asociada con la heterogeneidad del uso de suelo sobre la riqueza de especies de aves, la redundancia funcional, la diversidad funcional y sus componentes asociados (es decir, diversidad alfa, disimilitud de especies y fuerza de interacción de la relación entre la abundancia y la disimilitud funcional). Analizamos más de 200 ensamblajes georreferenciados de aves en el Bosque Atlántico de Brasil. Caracterizamos el papel funcional de las especies de cada ensamblaje y modelamos las medidas de biodiversidad como función de la cobertura forestal y de la heterogeneidad del uso de suelo. La sustitución del Bosque Atlántico nativo con un mosaico de usos de suelo (p. ej.: agricultura, pastura y urbanización) redujo la riqueza de especies de una manera no aleatoria. Las especies nucleares del bosque, o las especies consideradas como sensibles a los bordes, tendieron a estar ausentes en las comunidades de los ambientes heterogéneas. En general, la diversidad y la redundancia funcionales de las especies de aves no se vieron afectadas por la pérdida del bosque. Sin embargo, las aves en los hábitats con alta heterogeneidad eran funcionalmente distintas a las aves de los bosques, lo que sugiere un cambio en la composición x de la comunidad hacia especies exclusivas de mosaicos llevadas por la heterogeneidad de la cobertura del suelo. Las especies amenazadas del Bosque Atlántico no parecieron tolerar el ambiente degradado y heterogéneo pues permanecieron principalmente en las áreas con grandes extensiones de bosque. Nuestros resultados arrojan luz sobre los efectos complejos de la transformación de los bosques nativos en mosaicos de paisajes antropogénicos y recalcan la importancia de considerar los efectos de la deforestación y la heterogeneidad del uso de suelo cuando se evalúan los efectos de la deforestación sobre la biodiversidad neotropical.

Brain size predicts bees' tolerance to urban environments.

The rapid conversion of natural habitats to anthropogenic landscapes is threatening insect pollinators worldwide, raising concern regarding the negative consequences on their fundamental role as plant pollinators. However, not all pollinators are negatively affected by habitat conversion, as certain species find appropriate resources in anthropogenic landscapes to persist and proliferate. The reason why some species tolerate anthropogenic environments while most find them inhospitable remains poorly understood. The cognitive buffer hypothesis, widely supported in vertebrates but untested in insects, offers a potential explanation. This theory suggests that species with larger brains have enhanced behavioural plasticity, enabling them to confront and adapt to novel challenges. To investigate this hypothesis in insects, we measured brain size for 89 bee species, and evaluated their association with the degree of habitat occupancy. Our analyses revealed that bee species mainly found in urban habitats had larger brains relative to their body size than those that tend to occur in forested or agricultural habitats. Additionally, urban bees exhibited larger body sizes and, consequently, larger absolute brain sizes. Our results provide the first empirical support for the cognitive buffer hypothesis in invertebrates, suggesting that a large brain in bees could confer behavioural advantages to tolerate urban environments.

Marine Invertebrates: A Promissory Still Unexplored Source of Inhibitors of Biomedically Relevant Metallo Aminopeptidases Belonging to the M1 and M17 Families.

Proteolytic enzymes, also known as peptidases, are critical in all living organisms. Peptidases control the cleavage, activation, turnover, and synthesis of proteins and regulate many biochemical and physiological processes. They are also involved in several pathophysiological processes. Among peptidases, aminopeptidases catalyze the cleavage of the N-terminal amino acids of proteins or peptide substrates. They are distributed in many phyla and play critical roles in physiology and pathophysiology. Many of them are metallopeptidases belonging to the M1 and M17 families, among others. Some, such as M1 aminopeptidases N and A, thyrotropin-releasing hormone-degrading ectoenzyme, and M17 leucyl aminopeptidase, are targets for the development of therapeutic agents for human diseases, including cancer, hypertension, central nervous system disorders, inflammation, immune system disorders, skin pathologies, and infectious diseases, such as malaria. The relevance of aminopeptidases has driven the search and identification of potent and selective inhibitors as major tools to control proteolysis with an impact in biochemistry, biotechnology, and biomedicine. The present contribution focuses on marine invertebrate biodiversity as an important and promising source of inhibitors of metalloaminopeptidases from M1 and M17 families, with foreseen biomedical applications in human diseases. The results reviewed in the present contribution support and encourage further studies with inhibitors isolated from marine invertebrates in different biomedical models associated with the activity of these families of exopeptidases.

A test of Darwin's naturalization conundrum in birds reveals enhanced invasion success in the presence of close relatives.

Biological invasions pose one of the most severe environmental challenges of the twenty-first century. A longstanding idea is that invasion risk is predictable based on the phylogenetic distance - and hence ecological resemblance - between non-native and native species. However, current evidence is contradictory. To explain these mixed results, it has been proposed that the effect is scale-dependent, with invasion inhibited by phylogenetic similarity at small spatial scales but enhanced at larger scales. Analyzing invasion outcomes in a global sample of bird communities, we find no evidence to support this hypothesis. Instead, our results suggest that invaders are locally more successful in the presence of closely related and ecologically similar species, at least in human-altered environments where the majority of invasions have occurred. Functional trait analyses further confirm that the ecological niches of invaders are phylogenetically conserved, supporting the notion that successful invasion in the presence of close relatives is driven by shared adaptations to the types of niches available in novel environments.

Vultures as an overlooked model in cognitive ecology.

Despite important recent advances in cognitive ecology, our current understanding of avian cognition still largely rests on research conducted on a few model taxa. Vultures are an ecologically distinctive group of species by being the only obligate carrion consumers across terrestrial vertebrates. Their unique scavenging lifestyle suggests they have been subject to particular selective pressures to locate scarce, unpredictable, ephemeral, and nutritionally challenging food. However, substantial variation exists among species in diet, foraging techniques and social structure of populations. Here, we provide an overview of the current knowledge on vulture cognition through a comprehensive literature review and a compilation of our own observations. We find evidence for a variety of innovative foraging behaviors, scrounging tactics, collective problem-solving abilities and tool-use, skills that are considered indicative of enhanced cognition and that bear clear connections with the eco-social lifestyles of species. However, we also find that the cognitive basis of these skills remain insufficiently studied, and identify new research areas that require further attention in the future. Despite these knowledge gaps and the challenges of working with such large animals, we conclude that vultures may provide fresh insight into our knowledge of the ecology and evolution of cognition.

Niche shifts after island colonization spurred adaptive diversification and speciation in a cosmopolitan bird clade.

Islands have long been recognized as key contributors to biodiversity because they facilitate geographic isolation and ecological divergence from mainland ancestors. However, island colonization has traditionally been considered an evolutionary dead-end process, and its consequences for continental biodiversity remain understudied. Here, we use the evolutionary radiation of Columbiformes (i.e. pigeons and doves) to examine if ecological niche shifts on islands shaped biological diversification and community composition on continents. We show that the colonization of islands by continental, terrestrial-foraging lineages led to the exploitation of a new ecological niche (i.e. arboreal foraging). This transition towards arboreal foraging was associated with evolutionary adaptation towards a new morphological optimum. In addition, arboreal-foraging lineages of islands experienced an increase in speciation rates, which was associated with successful range expansions to other islands as well as back colonization of continents. Our results provide empirical evidence that diversification on continents can only be fully understood when studying the diversification processes that took place on islands, challenging the view of islands as mere sinks of evolutionary diversity.

Innovation in solitary bees is driven by exploration, shyness and activity levels.

Behavioural innovation and problem solving are widely considered to be important mechanisms by which animals respond to novel environmental challenges, including those induced by human activities. Despite their functional and ecological relevance, much of our current understanding of these processes comes from studies in vertebrates. Understanding of these processes in invertebrates has lagged behind partly because they are not perceived to have the cognitive machinery required. This perception is, however, challenged by recent evidence demonstrating sophisticated cognitive capabilities in insects despite their small brains. Here, we studied innovation, defined as the capacity to solve a new task, of a solitary bee (Osmia cornuta) in the laboratory by exposing naive individuals to an obstacle removal task. We also studied the underlying cognitive and non-cognitive mechanisms through a battery of experimental tests designed to measure associative learning, exploration, shyness and activity levels. We found that solitary bees can innovate, with 11 of 29 individuals (38%) being able to solve a new task consisting of lifting a lid to reach a reward. However, the propensity to innovate was uncorrelated with the measured learning capacity, but increased with exploration, boldness and activity. These results provide solid evidence that non-social insects can solve new tasks, and highlight the importance of interpreting innovation in the light of non-cognitive processes.

The worldwide impact of urbanisation on avian functional diversity.

Urbanisation is driving rapid declines in species richness and abundance worldwide, but the general implications for ecosystem function and services remain poorly understood. Here, we integrate global data on bird communities with comprehensive information on traits associated with ecological processes to show that assemblages in highly urbanised environments have substantially different functional composition and 20% less functional diversity on average than surrounding natural habitats. These changes occur without significant decreases in functional dissimilarity between species; instead, they are caused by a decrease in species richness and abundance evenness, leading to declines in functional redundancy. The reconfiguration and decline of native functional diversity in cities are not compensated by the presence of exotic species but are less severe under moderate levels of urbanisation. Thus, urbanisation has substantial negative impacts on functional diversity, potentially resulting in impaired provision of ecosystem services, but these impacts can be reduced by less intensive urbanisation practices.

Daily Nest Predation Rates Decrease with Body Size in Passerine Birds.

AbstractBody size evolution is generally framed by the benefits of being large, while costs are largely overlooked. An important putative cost of being large is the need to extend development periods, which should increase exposure to predation and potentially select against larger size. In birds, this selection pressure can be important because predation is the main source of offspring mortality and predators should more readily detect the larger nests associated with larger body sizes. Here, we show for diverse passerine birds across the world that counter to expectations, larger species suffer lower daily nest predation rates than smaller species. This pattern is consistent despite latitudinal variation in predation and does not seem to reflect a tendency of larger species to use more protected nests or less exposed nest locations. Evidence instead suggests that larger species attack a wider array of predator sizes, which could reduce predation rates in nests of large-bodied species. Regardless of the mechanism, the lower daily nest predation rates of larger species yield slightly lower predation rates over the entire development period compared with smaller species. These results highlight the importance of behavior as a mechanism to alter selection pressures and have implications for body size evolution.

Feeding specialization and longer generation time are associated with relatively larger brains in bees.

Despite their miniature brains, insects exhibit substantial variation in brain size. Although the functional significance of this variation is increasingly recognized, research on whether differences in insect brain sizes are mainly the result of constraints or selective pressures has hardly been performed. Here, we address this gap by combining prospective and retrospective phylogenetic-based analyses of brain size for a major insect group, bees (superfamily Apoidea). Using a brain dataset of 93 species from North America and Europe, we found that body size was the single best predictor of brain size in bees. However, the analyses also revealed that substantial variation in brain size remained even when adjusting for body size. We consequently asked whether such variation in relative brain size might be explained by adaptive hypotheses. We found that ecologically specialized species with single generations have larger brains-relative to their body size-than generalist or multi-generation species, but we did not find an effect of sociality on relative brain size. Phylogenetic reconstruction further supported the existence of different adaptive optima for relative brain size in lineages differing in feeding specialization and reproductive strategy. Our findings shed new light on the evolution of the insect brain, highlighting the importance of ecological pressures over social factors and suggesting that these pressures are different from those previously found to influence brain evolution in other taxa.

Fast attrition of springtail communities by experimental drought and richness-decomposition relationships across Europe.

Soil fauna play a fundamental role on key ecosystem functions like organic matter decomposition, although how local assemblages are responding to climate change and whether these changes may have consequences to ecosystem functioning is less clear. Previous studies have revealed that a continued environmental stress may result in poorer communities by filtering out the most sensitive species. However, these experiments have rarely been applied to climate change factors combining multiyear and multisite standardized field treatments across climatically contrasting regions, which has limited drawing general conclusions. Moreover, other facets of biodiversity, such as functional and phylogenetic diversity, potentially more closely linked to ecosystem functioning, have been largely neglected. Here, we report that the abundance, species richness, phylogenetic diversity, and functional richness of springtails (Subclass Collembola), a major group of fungivores and detritivores, decreased within 4 years of experimental drought across six European shrublands. The loss of phylogenetic and functional richness was higher than expected by the loss of species richness, leading to communities of phylogenetically similar species sharing evolutionary conserved traits. Additionally, despite the great climatic differences among study sites, we found that taxonomic, phylogenetic, and functional richness of springtail communities alone were able to explain up to 30% of the variation in annual decomposition rates. Altogether, our results suggest that the forecasted reductions in precipitation associated with climate change may erode springtail communities and likely other drought-sensitive soil invertebrates, thereby retarding litter decomposition and nutrient cycling in ecosystems.

Semisynthesis, cytotoxicity, antimalarial evaluation and structure-activity relationship of two series of triterpene derivatives.

In this report, we describe the semisynthesis of two series of ursolic and betulinic acid derivatives through designed by modifications at the C-3 and C-28 positions and demonstrate their antimalarial activity against chloroquine-resistant P. falciparum (W2 strain). Structural modifications at C-3 were more advantageous to antimalarial activity than simultaneous modifications at C-3 and C-28 positions. The ester derivative, 3ß-butanoyl betulinic acid (7b), was the most active compound (IC50 = 3.4 µM) and it did not exhibit cytotoxicity against VERO nor HepG2 cells (CC50 > 400 µM), showing selectivity towards parasites (selectivity index > 117.47). In combination with artemisinin, compound 7b showed an additive effect (CI = 1.14). While docking analysis showed a possible interaction of 7b with the Plasmodium protease PfSUB1, with an optimum binding affinity of -7.02 kcal/mol, the rather low inhibition displayed on a Bacillus licheniformis subtilisin A protease activity assay (IC50 = 93 µM) and the observed accumulation of ring forms together with a delay of appearance of trophozoites in vitro suggests that the main target of 3ß-butanoyl betulinic acid on Plasmodium may be related to other molecules and processes pertaining to the ring stage. Therefore, compound 7b is the most promising compound for further studies on antimalarial chemotherapy. The results obtained in this study provide suitable information about scaffolds to develop novel antimalarials from natural sources.

Urbanisation and the loss of phylogenetic diversity in birds.

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.

Tropical insect diversity: evidence of greater host specialization in seed-feeding weevils.

Host specialization has long been hypothesized to explain the extraordinary diversity of phytophagous insects in the tropics. However, addressing this hypothesis has proved challenging because of the risk of over-looking rare interactions, and hence biasing specialization estimations, and the difficulties to separate the diversity component attributable to insect specialization from that related to host diversity. As a result, the host specialization hypothesis lacks empirical support for important phytophagous insect clades. Here, we test the hypothesis in a radiation of seed-feeding insects, acorn weevils (Curculio spp.), sampled in temperate and tropical regions (California and Nicaragua, respectively) with an equivalent pool of oak host species. Using DNA sequences from three low-copy genes, we delimited to species level 778 weevil larvae extracted from host seeds and assessed their phylogenetic relationships by Maximum Likelihood and Bayesian inference. We then reconstructed the oak-weevil food webs and examined differences in alpha, beta and gamma diversity using Hill numbers of effective species. We found a higher alpha, beta and gamma diversity of weevils in Nicaragua compared to California despite similar richness of host species at both local and regional level. By means of Bayesian mixed models, we also found that tropical weevil species were highly specialized both in terms of host range and interaction strength, whereas their temperate congeners had a broader taxonomic and phylogenetic host spectrum. Finally, in Nicaraguan species, larval body size was highly correlated with the size of the acorns infested, as would be expected by a greater host specialization, whereas in California this relationship was absent. Altogether, these lines of evidence support the host specialization hypothesis and suggest contrasting eco-evolutionary dynamics in tropical and temperate regions even in absence of differences in host diversity.

Relative Brain Size and Its Relation with the Associative Pallium in Birds.

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.

Template Synthesis, Metalation, and Self-Assembly of Protic Gold(I)/(NHC)2 Tectons Driven by Metallophilic Interactions.

A new protocol for the synthesis of protic bis(N-heterocyclic carbene) complexes of Au(I) by a stepwise metal-controlled coupling of isocyanide and propargylamine is described. They are used as tectons for the construction of supramolecular architectures through metalation and self-assembly. Notably a unique polymeric chain of Cu(I) with alternate Au(I) /bis(imidazolate) bridging scaffolds and strong unsupported Cu(I) -Cu(I) interactions has been generated, as well as a 28-metal-atoms cluster containing a nanopiece of Cu2 O trapped by peripheral Au(I) /bis(imidazolate) moieties.

Urbanisation tolerance and the loss of avian diversity.

Urbanisation is considered an important driver of current biodiversity loss, but the underlying causes are not fully understood. It is generally assumed that this loss reflects the fact that most organisms do not tolerate well the environmental alterations associated with urbanisation. Nevertheless, current evidence is inconclusive and the alternative that the biodiversity loss is the result of random mechanisms has never been evaluated. Analysing changes in abundance between urbanised environments and their non-urbanised surroundings of > 800 avian species from five continents, we show here that although random processes account for part of the species loss associated with urbanisation, much of the loss is associated with a lack of appropriate adaptations of most species for exploiting resources and avoiding risks of the urban environments. These findings have important conservation implications because the extinction of species with particular features should have higher impact on biodiversity and ecosystem function than a random loss.

Light conditions and the evolution of the visual system in birds.

Despite vision being an essential sense for many animals, the intuitively appealing notion that the visual system has been shaped by environmental light conditions is backed by insufficient evidence. Based on a comprehensive phylogenetic comparative analysis of birds, we investigate if exposure to different light conditions might have triggered evolutionary divergence in the visual system through pressures on light sensitivity, visual acuity, and neural processing capacity. Our analyses suggest that birds that have adopted nocturnal habits evolved eyes with larger corneal diameters and, to a lesser extent, longer axial length than diurnal species. However, we found no evidence that sensing and processing organs were selected together, as observed in diurnal birds. Rather than enlarging the processing centers, we found a tendency among nocturnal species to either reduce or maintain the size of the two main brain centers involved in vision-the optic tectum and the wulst. These results suggest a mosaic pattern of evolution, wherein optimization of the eye optics for efficient light capture in nocturnal species may have compromised visual acuity and central processing capacity.

Toward a unified framework for studying behavioural tolerance.

Behavioural responses are widely held to allow animals to cope with human-induced environmental changes. Less often appreciated is that the absence of behavioural response can also be advantageous. This is particularly true when animals become tolerant to situations that may be perceived as risky, although the actual risk is nonexistent. We provide a framework to understand the causes and consequences of behavioural tolerance. Tolerance can emerge from genetic, epigenetic, or learning mechanisms, each exerting different degrees of influence on its speed of acquisition, reversibility, specificity, and duration. The ultimate impact on fitness hinges on the interplay between these mechanisms and the nature of the stressor. Mechanistic clarity is therefore essential to better understand and manage human-wildlife interactions in the Anthropocene.

Addressing a critique of the TEASI framework for invasive species risk assessment.

We address criticism that the Transport, Establishment, Abundance, Spread, Impact (TEASI) framework does not facilitate objective mapping of risk assessment methods nor defines best practice. We explain why TEASI is appropriate for mapping, despite inherent challenges, and how TEASI offers considerations for best practices, rather than suggesting one best practice.