The α, β, γ diversity decomposition methodology is commonly used to investigate changes in diversity over space or time but rarely conjointly. However, with the ever-increasing availability of large-scale biodiversity monitoring data, there is a need for a sound methodology capable of simultaneously accounting for spatial and temporal changes in diversity.Using the properties of Chao’s index, we adapted Rao’s framework of diversity decomposition between orthogonal dimensions to a multiplicative α, β, γ decomposition of functional or phylogenetic diversity over space and time, thereby combining their respective properties. We also developed guidelines for interpreting both temporal and spatial β-diversities and their interaction.We characterised the range of β-diversity estimates and their relationship to the nested decomposition of diversity. Using simulations, we empirically demonstrated that temporal and spatial β-diversities are independent from each other and from α and γ-diversities when the study design is balanced, but not otherwise. Furthermore, we showed that the interaction term between the temporal and the spatial β-diversities lacked such properties.We illustrated our methodology with a case study of the spatio-temporal dynamics of functional diversity in bird assemblages in four regions of France. Based on these data, our method makes it possible to discriminate between regions experiencing different diversity changes in time. Our methodology may therefore be valuable for comparing diversity changes over space and time using large-scale datasets of repeated surveys.
β-diversity; biodiversity; phylogenetic entropy; Shannon entropy; Hill numbers; diversity partitioning; bird assemblages; large-scale monitoring; turn-over
To define biome-scale hotspots of phylogenetic and functional mammalian biodiversity (PD and FD, respectively) and compare them to ‘classical’ hotspots based on species richness (SR) only.
SR, PD & FD were computed for 782 terrestrial ecoregions using distribution ranges of 4616 mammalian species. We used a set of comprehensive diversity indices unified by a recent framework that incorporates the species relative coverage in each ecoregion. We build large-scale multifaceted diversity-area relationships to rank ecoregions according to their levels of biodiversity while accounting for the effect of area on each diversity facet. Finally we defined hotspots as the top-ranked ecoregions.
While ignoring species relative coverage led to a relative good congruence between biome top ranked SR, PD and FD hotspots, ecoregions harboring a rich and abundantly represented evolutionary history and functional diversity did not match with top ranked ecoregions defined by species richness. More importantly PD and FD hotspots showed important spatial mismatches. We also found that FD and PD generally reached their maximum values faster than species richness as a function of area.
The fact that PD/FD reach faster their maximal value than SR may suggest that the two former facets might be less vulnerable to habitat loss than the latter. While this point is expected, it is the first time that it is quantified at global scale and should have important consequences in conservation. Incorporating species relative coverage into the delineation of multifaceted hotspots of diversity lead to weak congruence between SR, PD and FD hotspots. This means that maximizing species number may fail at preserving those nodes (in the phylogenetic or functional tree) that are relatively abundant in the ecoregion. As a consequence it may be of prime importance to adopt a multifaceted biodiversity perspective to inform conservation strategies at global scale.
phylogenetic diversity area-relationship; functional diversity area-relationship; species area-relationship; conservation biogeography; diversity indices; Hill’s numbers; mammals
We assessed the temporal trends of taxonomic, functional and phylogenetic diversities in the French avifauna over the last two decades. Additionally, we investigated whether and how this multifaceted approach to biodiversity dynamics can reveal an increasing similarity of local assemblages in terms of species, traits and/or lineages.
We analysed a large-scale dataset that recorded annual changes in the abundance of 116 breeding birds in France between 1989 and 2012. We decomposed and analysed the spatio-temporal dynamics of taxonomic, phylogenetic and functional diversities and each of their α-, β- and γ-components. We also calculated the trend in the mean specialization of bird communities to track the relative success of specialist versus generalist species within communities during the same period.
We found large variation within and among the temporal trends of each biodiversity facet. On average, we found a marked increase in species and phylogenetic diversity over the period considered, but no particular trend was found for functional diversity. Conversely, changes in β-diversities for the three facets were characterized by independent and nonlinear trends. We also found a general increase in the local occurrence and abundance of generalist species within local communities.
These results highlight a relative asynchrony of the different biodiversity facets occurring at large spatial scales. We show why a multifaceted approach to biodiversity dynamics is needed to better describe and understand changes in community composition in macroecology and conservation biogeography.
Beta diversity; breeding bird survey; functional traits; homogenization; Rao; species turnover; temporal dynamics
We investigate patterns of phylogenetic diversity in relation to species diversity for European birds, mammals and amphibians, to evaluate their congruence and highlight areas of particular evolutionary history. We estimate the extent to which the European network of protected areas (PAs) network retains interesting evolutionary history areas for the three groups separately and simultaneously.
Phylogenetic (QEPD) and species diversity (SD) were estimated using the Rao’s quadratic entropy at 10′ resolution. We determined the regional relationship between QEPD and SD for each taxa with a spatial regression model and used the tails of the residuals (QERES) distribution to identify areas of higher and lower QEPD than predicted. Spatial congruence of biodiversity between groups was assessed with Pearson’s correlation. A simple classification scheme allowed building a convergence map where a convergent pixel equalled to a QERES value of the same sign for the 3 groups. This convergence map was overlaid to the current PAs network to estimate the level of protection in convergent pixels and compared it to a null expectation built on 1000 randomization of PAs over the landscape.
QERES patterns across vertebrates show a strong spatial mismatch highlighting different evolutionary histories. Convergent areas represent only 2.7% of the Western Palearctic, with only 8.4% of these areas being covered by the current PAs network while a random distribution would retain 10.4% of them. QERES are unequally represented within PAs: areas with higher QEPD than predicted are better covered than expected, while low QEPD areas are undersampled.
Patterns of diversity strongly diverge between groups of vertebrates in Europe. Although Europe has the world’s most extensive PAs network, evolutionary history of terrestrial vertebrates is unequally protected. The challenge is now to reconcile effective conservation planning with a contemporary view of biodiversity integrating multiple facets.
Phylogenetic diversity; protected areas; spatial biodiversity congruence; species diversity; terrestrial vertebrates; Europe
Biotic homogenization (BH) is a process whereby some species (losers) are systematically replaced by others (winners). While this process has been related to the effects of anthropogenic activities, whether and how BH is occurring across regions and the role of native species as a driver of BH has hardly been investigated. Here, we examine the trend in the community specialization index (CSI) for 234 native species of breeding birds at 10 111 sites in six European countries from 1990 to 2008. Unlike many BH studies, CSI uses abundance information to estimate the balance between generalist and specialist species in local assemblages. We show that bird communities are more and more composed of native generalist species across regions, revealing a strong, ongoing BH process. Our result suggests a rapid and non-random change in community composition at a continental scale is occurring, most likely driven by anthropogenic activities.
habitat specialization; community specialization index; breeding bird survey; macroecology
Effects of climate change on species occupying distinct areas during their life cycle are still unclear. Moreover, although effects of climate change have widely been studied at the species level, less is known about community responses. Here, we test whether and how the composition of wader (Charadrii) assemblages, breeding in high latitude and wintering from Europe to Africa, is affected by climate change over 33 years. We calculated the temporal trend in the community temperature index (CTI), which measures the balance between cold and hot dwellers present in species assemblages. We found a steep increase in the CTI, which reflects a profound change in assemblage composition in response to recent climate change. This study provides, to our knowledge, the first evidence of a strong community response of migratory species to climate change in their wintering areas.
climate change; waders; assemblages; community temperature index; estuaries
Human land use and climate change are regarded as the main driving forces of present-day and future species extinction. They may potentially lead to a profound reorganisation of the composition and structure of natural communities throughout the world. However, studies that explicitly investigate both forms of impact—land use and climate change—are uncommon. Here, we quantify community change of Dutch breeding bird communities over the past 25 years using time lag analysis. We evaluate the chronological sequence of the community temperature index (CTI) which reflects community response to temperature increase (increasing CTI indicates an increase in relative abundance of more southerly species), and the temporal trend of the community specialisation index (CSI) which reflects community response to land use change (declining CSI indicates an increase of generalist species). We show that the breeding bird fauna underwent distinct directional change accompanied by significant changes both in CTI and CSI which suggests a causal connection between climate and land use change and bird community change. The assemblages of particular breeding habitats neither changed at the same speed and nor were they equally affected by climate versus land use changes. In the rapidly changing farmland community, CTI and CSI both declined slightly. In contrast, CTI increased in the more slowly changing forest and heath communities, while CSI remained stable. Coastal assemblages experienced both an increase in CTI and a decline in CSI. Wetland birds experienced the fastest community change of all breeding habitat assemblages but neither CTI nor CSI showed a significant trend. Overall, our results suggest that the interaction between climate and land use changes differs between habitats, and that comparing trends in CSI and CTI may be useful in tracking the impact of each determinant.
Predicting species' responses to the combined effects of habitat and climate changes has become a major challenge in ecology and conservation biology. However, the effects of climatic and habitat gradients on species distributions have generally been considered separately. Here, we explore the relationships between the habitat and thermal dimensions of the ecological niche in European common birds. Using data from the French Breeding Bird Survey, a large-scale bird monitoring program, we correlated the habitat and thermal positions and breadths of 74 bird species, controlling for life history traits and phylogeny. We found that cold climate species tend to have niche positions in closed habitats, as expected by the conjunction of the biogeographic history of birds' habitats, and their current continent-scale gradients. We also report a positive correlation between thermal and habitat niche breadths, a pattern consistent with macroecological predictions concerning the processes shaping species' distributions. Our results suggest that the relationships between the climatic and habitat components of the niche have to be taken into account to understand and predict changes in species' distributions.
Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year growth rates of 62 terrestrial breeding birds in three European countries along the latitudinal gradient of the species ranges. After controlling for factors already reported to affect bird population trends (habitat specialization, migration distance and body mass), we found that populations breeding close to the species thermal maximum have lower growth rates than those in other parts of the thermal range, while those breeding close to the species thermal minimum have higher growth rates. These results were maintained even after having controlled for the effect of latitude per se. Therefore, the results cannot solely be explained by latitudinal clines linked to the geographical structure in local spring warming. Indeed, we found that populations are not just responding to changes in temperature at the hottest and coolest parts of the species range, but that they show a linear graded response across their European thermal range. We thus provide insights into how populations respond to climate changes. We suggest that projections of future species distributions, and also management options and conservation assessments, cannot be based on the assumption of a uniform response to climate change across a species range or at range edges only.
biological traits; breeding bird monitoring; climate warming; climatic niche; population growth rate; thermal maximum
The 2011 meeting of the European Ecological Federation took place in Ávila, Spain, from 26th September to 29th September. The French Ecological Society (SFE) and the Foundation for Research on Biodiversity (FRB) sponsored a session entitled ‘Evolutionary history, ecosystem function and conservation biology: new perspectives’. We report on the main insights obtained from this symposium.
conservation; phylogenies diversity; biodiversity; macroevolution
Range shifts of many species are now documented as a response to global warming. But whether these observed changes are occurring fast enough remains uncertain and hardly quantifiable. Here, we developed a simple framework to measure change in community composition in response to climate warming. This framework is based on a community temperature index (CTI) that directly reflects, for a given species assemblage, the balance between low- and high-temperature dwelling species. Using data from the French breeding bird survey, we first found a strong increase in CTI over the last two decades revealing that birds are rapidly tracking climate warming. This increase corresponds to a 91 km northward shift in bird community composition, which is much higher than previous estimates based on changes in species range edges. During the same period, temperature increase corresponds to a 273 km northward shift in temperature. Change in community composition was thus insufficient to keep up with temperature increase: birds are lagging approximately 182 km behind climate warming. Our method is applicable to any taxa with large-scale survey data, using either abundance or occurrence data. This approach can be further used to test whether different delays are found across groups or in different land-use contexts.
birds; breeding bird survey; climate warming; community composition; global changes; range edges