Traits such as clutch size vary markedly across species and environmental gradients but have usually been investigated from either a comparative or a geographic perspective, respectively. We analyzed ...the global variation in clutch size across 5,290 bird species, excluding brood parasites and pelagic species. We integrated intrinsic (morphological, behavioural), extrinsic (environmental), and phylogenetic effects in a combined model that predicts up to 68% of the interspecific variation in clutch size. We then applied the same species-level model to predict mean clutch size across 2,521 assemblages worldwide and found that it explains the observed eco-geographic pattern very well. Clutches are consistently largest in cavity nesters and in species occupying seasonal environments, highlighting the importance of offspring and adult mortality that is jointly expressed in intrinsic and extrinsic correlates. The findings offer a conceptual bridge between macroecology and comparative biology and provide a global and integrative understanding of the eco-geographic and cross-species variation in a core life-history trait.
The effects of different environmental drivers on the changes in species’ population abundances can be difficult to disentangle as they often act simultaneously. Researchers have built statistical ...models that include environmental variables (such as annual temperature) or species attributes (such as a species’ temperature preference), which are assumed to detect the impacts of specific drivers (such as climate change). However, these approaches are often applied separately or, if combined, not explicitly compared.
We show the complementary insights gained by applying both these approaches to a community dataset on Danish terrestrial birds. We use our analysis to compare the relative importance of climate change and agricultural land‐use change for the abundance changes within the community between 1983 and 2013.
Population models were fitted to the community data of species’ annual abundances with predictors comprising: species attributes (species’ temperature and habitat preferences), environmental variables (climatic and agricultural land‐use change variables) or both. Relationships between species’ abundances and environmental variables were used to identify the drivers associated with average abundance changes of species in the community. Relationships between species’ abundances and their attributes were used to understand the drivers causing interspecific variation in abundance changes.
Warmer winters were positively associated with community‐level abundances, and warm‐adapted species had more positive abundance changes than cold‐adapted ones. Agricultural land‐use area was negatively associated with community‐level abundances, and birds using a high proportion of meadow and habitat specialists had more negative abundance changes than birds using other habitats and habitat generalists. Effect sizes of environmental variables were larger for agricultural land‐use change while those of species attributes were larger for climate change.
The environmental data approach suggested that agricultural land‐use change has decreased the average abundances of species in the community, affecting total community size while the species attribute‐based approach suggested that climate change has caused variation in abundance among species, affecting community composition. Environmental variables and species attributes that are hypothesized to link to specific drivers can be used together to provide complementary information on the impacts of different drivers on communities.
Climate change and land‐use change are already known to have affected bird’ population abundances in Europe. By a novel methodology comparing impacts at the community‐level, the authors show that agricultural land‐use change has decreased total community size, while climate change has rather caused changes in community composition.
Wildlife tourism is an important cultural ecosystem service, benefiting regional economies and biodiversity conservation. Many wildlife tourism destinations remain below their visitor and income ...capacities. Management strategies are needed that increase visitor satisfaction and a destination's reputation to attract more visitors. Wildlife tourism can be directly linked to biodiversity, but might also be directly and indirectly influenced by other factors, such as landscape features or infrastructure. We investigated the relationships between visitor numbers and biodiversity, along with other factors, in a major wildlife tourism destination using structural equation modeling and additionally assessed visitors' expectations and viewing preferences. We simultaneously recorded large mammal and visitor data along 78 road transects in Kruger National Park (KNP), South Africa, and conducted interviews with visitors. We also collected data on vegetation cover, visibility, landscape features and infrastructure. We found high visitor numbers at transects with high sighting probabilities of large predators, while other factors, e.g. ungulate densities or infrastructure, were only weakly associated with visitor numbers. Consistently, interview results suggested that seeing wildlife was the main reason for visiting the park, and large predators, especially lions and leopards, ranked highest among the visitors' wildlife preferences. Our results demonstrate that wildlife tourists in KNP are primarily attracted to large predators. To meet visitor expectations and to increase visitor numbers, park management should focus on the conservation of natural savannah ecosystems with large predator and prey populations. With such an ecosystem-based management, biodiversity conservation can be successful while securing wildlife tourism and its revenues.
•In African savannah, visitor numbers increased with predator sighting probability.•In particular lion and leopard attracted high numbers of visitors.•Landscape and infrastructure were also directly and indirectly related to visitors.•Large predators can only be sustained in near-natural habitats with sufficient prey.•Wildlife management should target the conservation of natural savannah ecosystems.
The species composition of local communities varies in space, and its similarity generally decreases with increasing geographic distance between communities, a phenomenon known as distance decay of ...similarity. It is, however, not known how changes in local species composition affect ecological processes, that is, whether they lead to differences in the local composition of species' functional roles. We studied eight seed-dispersal networks along the South American Andes and compared them with regard to their species composition and their composition of functional roles. We tested (1) if changes in bird species composition lead to changes in the composition of bird functional roles, and (2) if the similarity in species composition and functional-role composition decreased with increasing geographic distance between the networks. We also used cluster analysis to (3) identify bird species with similar roles across all networks based on the similarity in the plants they consume, (i) considering only the species identity of the plants and (ii) considering the functional traits of the plants. Despite strong changes in species composition, the networks along the Andes showed similar composition of functional roles. (1) Changes in species composition generally did not lead to changes in the composition of functional roles. (2) Similarity in species composition, but not functional-role composition, decreased with increasing geographic distance between the networks. (3) The cluster analysis considering the functional traits of plants identified bird species with similar functional roles across all networks. The similarity in functional roles despite the high species turnover suggests that the ecological process of seed dispersal is organized similarly along the Andes, with similar functional roles fulfilled locally by different sets of species. The high species turnover, relative to functional turnover, also indicates that a large number of bird species are needed to maintain the seed-dispersal process along the Andes.
Climate change and other anthropogenic drivers of biodiversity change are unequally distributed across the world. Overlap in the distributions of different drivers have important implications for ...biodiversity change attribution and the potential for interactive effects. However, the spatial relationships among different drivers and whether they differ between the terrestrial and marine realm has yet to be examined.
We compiled global gridded datasets on climate change, land‐use, resource exploitation, pollution, alien species potential and human population density. We used multivariate statistics to examine the spatial relationships among the drivers and to characterize the typical combinations of drivers experienced by different regions of the world.
We found stronger positive correlations among drivers in the terrestrial than in the marine realm, leading to areas with high intensities of multiple drivers on land. Climate change tended to be negatively correlated with other drivers in the terrestrial realm (e.g. in the tundra and boreal forest with high climate change but low human use and pollution), whereas the opposite was true in the marine realm (e.g. in the Indo‐Pacific with high climate change and high fishing).
We show that different regions of the world can be defined by Anthropogenic Threat Complexes (ATCs), distinguished by different sets of drivers with varying intensities. We identify 11 ATCs that can be used to test hypotheses about patterns of biodiversity and ecosystem change, especially about the joint effects of multiple drivers.
Our global analysis highlights the broad conservation priorities needed to mitigate the impacts of anthropogenic change, with different priorities emerging on land and in the ocean, and in different parts of the world.
Abstrakt
Der Klimawandel und andere anthropogene Faktoren, die die biologische Vielfalt verändern, betreffen nicht alle Teile der Erde in gleicher Weise. Während unsere Kenntnisse zu jedem einzelnen Gefährdungsfaktor ständig wachsen, ist unser Verständnis zu den räumlichen Beziehungen zwischen den verschiedenen Faktoren und ihr Zusammenwirken noch sehr mangelhaft. Das betrifft z.B. auch die Unterschiede zwischen terrestrischen und marinen Lebensräumen, die sehr unterschiedlichen Bedrohungen ausgesetzt sein können, selbst wenn sie eng benachbart sind.
In der vorliegenden Studie haben wir globale Datensätze über Klimawandel, Landnutzung, Ressourcenausbeutung, Umweltverschmutzung, biologische Invasionen und Bevölkerungsdichte zusammengestellt. Mit Hilfe multivariater Statistiken haben wir die räumlichen Beziehungen zwischen diesen Ursachen des globalen Biodiversitätswandels und deren Kombinationen untersucht, um deren Einfluss auf verschiedene Regionen der Welt zu charakterisieren.
Insbesondere in den terrestrischen Regionen wirken die genannten Gefährdungsfaktoren häufig in der gleichen Richtung, vor allem solche, die zum Teil besonders hohe Belastungen darstellen. Regionen mit stärker ausgeprägtem Klimawandel sind tendenziell solche Gebiete, in denen die Gefährdung durch andere Faktoren eher geringer ist, wie z.B. in der Tundra und im borealen Nadelwald, die stark vom Klimawandel, aber weniger von hoher Nutzungsintensität und Verschmutzung betroffen sind. Dagegen treten in den Meeresregionen gegenteilige Muster auf, wo z.B. im Indopazifik ein sehr ausgeprägter Klimawandel einer hoher Ressourcenausbeutung durch Fischerei zusammenfällt.
Die Regionen der Welt lassen sich in Klassen unterschiedlicher Interaktionen und Intensitäten dieser anthropogenen Gefährungsfaktoren unterteilen. Diese insgesamt 11 verschiedene Faktorenklassen können nun dazu verwendet werden, Auswirkungen auf Biodiversität zu untersuchen und die Gefährdungs‐Hotspots zu identifizieren. Diese Hotspots sind diejenigen großräumigen Meeres‐ und Festlandsregionen, in denen prioritär Naturschutzmaßnahmen angewendet werden müssen, um den Auswirkungen des anthropogenen Biodiversitätswandels entgegenzutreten.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
Aim: An important, unresolved question in macroecology is to understand the immense inter-specific variation in geographic range sizes. While species traits such as fecundity or body size are thought ...to affect range sizes, a general understanding on how multiple traits jointly influence them is missing. Here, we test the influence of a multitude of species traits on global range sizes of European passerine birds in order to better understand possible mechanisms behind macroecological relationships. Location :Global. Methods: We evaluated the effect of life-history traits (fecundity, dispersal ability), ecological traits (habitat niche, diet niche, migratory behaviour, migratory flexibility) and a morphological trait (body size) on the global range sizes of 165 European passerines. We identified hypotheses from the literature relating traits to range size and used path analysis to test them. Results: Fecundity, dispersal ability and habitat niche breadth had a direct positive effect on range size. Diet niche position had a direct negative effect on range size. Habitat niche breadth also had an indirect positive effect via higher fecundity. Migratory behaviour had an indirect positive effect via better dispersal ability. Body size had a strong positive direct effect which was reduced by negative indirect effects via several other traits. Main conclusions: Geographic range sizes of European passerines were influenced by life-history traits (fecundity and dispersal ability), ecological traits (habitat niche breadth, diet niche position and migratory behaviour) and by body size. Traits influenced range size both directly and indirectly. Body size effects were particularly complex, with positive and negative effects acting over different pathways. We show that it is necessary to disentangle the direct and indirect influence of multiple traits on range size to better elucidate the mechanisms that generate macroecological relationships.
The colors of fleshy fruits are considered to be a signal to seed-dispersing animals, but their diversity remains poorly understood. Using an avian color space to derive a sensory morphospace for ...fruit color, we tested four hypotheses of fruit color diversity: fruit colors occupy a limited area of the color space; they are less diverse than flower colors; fruit colors within localities are similar to each other; and fruit color diversity reflects phylogeny.
The global fruit color diversity of 948 primarily bird-dispersed plant species and the color diversity of localities were compared with null models of random, unconstrained evolution of fruit color. Fruit color diversity was further compared with the diversity of 1300 flower colors. Tests of phylogenetic effects on fruit color were used to assess the degree of correspondence with phylogeny.
Global and local fruit color diversity was limited compared with null models and fruits have achieved only half the color diversity of flowers. Interestingly, we found little indication of phylogenetic conservatism.
Constraints resulting from the chemical properties of pigments probably limit global fruit and flower color diversity. Different types of selection on fruits and flowers may further explain the smaller color diversity of fruits.
Pollinator‐mediated interactions between plants can play an important role for the dynamics of plant communities. Pollination services depend on the abundance and the foraging behaviour of ...pollinators, which in turn respond to the availability and distribution of floral resources (notably nectar sugar). However, it is still insufficiently understood how the ‘sugar landscapes’ provided by flowering plant communities shape pollinator‐mediated interactions between multiple plant species and across different spatial scales. A better understanding of pollinator‐mediated interactions requires an integrative approach that quantifies different aspects of sugar landscapes and investigates their relative importance for pollinator behaviour and plant reproductive success. In this study, we quantified such sugar landscapes from individual‐based maps of Protea shrub communities in the Cape Floristic Region, South Africa. The 27 study sites of 4 ha each jointly comprise 127 993 individuals of 19 species. We analysed how rates of visitation by key bird pollinators and the seed set of plants respond to different aspects of sugar landscapes: the distribution of nectar sugar amounts, as well as their quality, taxonomic purity and phenology. We found that pollinator visitation rates strongly depended on phenological variation of site‐scale sugar amounts. The seed set of focal plants increased with nectar sugar amounts of conspecific neighbours and with site‐scale sugar amounts. Seed set increased particularly strongly if site‐scale sugar amounts were provided by plants that offer less sugar per inflorescence. These combined effects of the amount, quality, purity and phenological variation of nectar sugar show that nectar sugar is a common interaction currency that determines how multiple plant species interact via shared pollinators. The responses of pollinator‐mediated interactions to different aspects of this interaction currency alter conditions for species coexistence in Protea communities and may cause community‐level Allee effects that promote extinction cascades.
Although it is generally recognized that global biodiversity is declining, few studies have examined long‐term changes in multiple biodiversity dimensions simultaneously. In this study, we quantified ...and compared temporal changes in the abundance, taxonomic diversity, functional diversity, and phylogenetic diversity of bird assemblages, using roadside monitoring data of the North American Breeding Bird Survey from 1971 to 2010. We calculated 12 abundance and diversity metrics based on 5‐year average abundances of 519 species for each of 768 monitoring routes. We did this for all bird species together as well as for four subgroups based on breeding habitat affinity (grassland, woodland, wetland, and shrubland breeders). The majority of the biodiversity metrics increased or remained constant over the study period, whereas the overall abundance of birds showed a pronounced decrease, primarily driven by declines of the most abundant species. These results highlight how stable or even increasing metrics of taxonomic, functional, or phylogenetic diversity may occur in parallel with substantial losses of individuals. We further found that patterns of change differed among the species subgroups, with both abundance and diversity increasing for woodland birds and decreasing for grassland breeders. The contrasting changes between abundance and diversity and among the breeding habitat groups underscore the relevance of a multifaceted approach to measuring biodiversity change. Our findings further stress the importance of monitoring the overall abundance of individuals in addition to metrics of taxonomic, functional, or phylogenetic diversity, thus confirming the importance of population abundance as an essential biodiversity variable.
Climate and land-use change interactively affect biodiversity. Large-scale expansions of bioenergy have been suggested as an important component for climate change mitigation. Here we use harmonized ...climate and land-use projections to investigate their potential combined impacts on global vertebrate diversity under a low- and a high-level emission scenario. We combine climate-based species distribution models for the world’s amphibians, birds, and mammals with land-use change simulations and identify areas threatened by both climate and land-use change in the future. The combined projected effects of climate and land-use change on vertebrate diversity are similar under the two scenarios, with land-use change effects being stronger under the low- and climate change effects under the high-emission scenario. Under the low-emission scenario, increases in bioenergy cropland may cause severe impacts in biodiversity that are not compensated by lower climate change impacts. Under this low-emission scenario, larger proportions of species distributions and a higher number of small-range species may become impacted by the combination of land-use and climate change than under the high-emission scenario, largely a result of bioenergy cropland expansion. Our findings highlight the need to carefully consider both climate and land-use change when projecting biodiversity impacts. We show that biodiversity is likely to suffer severely if bioenergy cropland expansion remains a major component of climate change mitigation strategies. Our study calls for an immediate and significant reduction in energy consumption for the benefit of both biodiversity and to achieve the goals of the Paris Agreement.
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