Experimental evidence of impacts of an invasive parakeet on foraging behavior of native birds.

Resource competition is one potential behavioral mechanism by which invasive species can impact native species, but detecting this competition can be difficult due to the interactions that variable environmental conditions can have on species behavior. This is particularly the case in urban habitats where the disturbed environment can alter natural behavior from that in undisturbed habitats. The rose-ringed parakeet (), is an increasingly common invasive species, predominantly associated with large urban centers.

What is macroecology?

The symposium 'What is Macroecology?' was held in London on 20 June 2012. The event was the inaugural meeting of the Macroecology Special Interest Group of the British Ecological Society and was attended by nearly 100 scientists from 11 countries. The meeting reviewed the recent development of the macroecological agenda.

Migratory behavior of birds affects their coevolutionary relationship with blood parasites.

Host traits, such as migratory behavior, could facilitate the dispersal of disease-causing parasites, potentially leading to the transfer of infections both across geographic areas and between host species. There is, however, little quantitative information on whether variation in such host attributes does indeed affect the evolutionary outcome of host-parasite associations. Here, we employ Leucocytozoon blood parasites of birds, a group of parasites closely related to avian malaria, to study host-parasite coevolution in relation to host behavior using a phylogenetic comparative approach.

Speciation and extinction drive the appearance of directional range size evolution in phylogenies and the fossil record.

While the geographic range of a species is a fundamental unit of macroecology and a leading predictor of extinction risk, the evolutionary dynamics of species' ranges remain poorly understood. Based on statistical associations between range size and species age, many studies have claimed support for general models of range evolution in which the area occupied by a species varies predictably over the course of its life. Such claims have been made using both paleontological data and molecular estimates of the age of extant species.

Biogeography of avian blood parasites (Leucocytozoon spp.) in two resident hosts across Europe: phylogeographic structuring or the abundance-occupancy relationship?

Relationships between hosts and parasites represent complex co-evolving systems that can vary both temporally and spatially. This variation may result in different phylogeographic outcomes, ranging from highly geographically structured parasite populations comprised of specialist lineages that are locally abundant but have restricted global occupancy to geographically unstructured parasite populations consisting of widespread parasites. Here, we present results from a large biogeographic study of the Leucocytozoon blood parasites of two nonmigrant bird species, conducted at nine sites across Europe.

The shape and temporal dynamics of phylogenetic trees arising from geographic speciation.

Phylogenetic trees often depart from the expectations of stochastic models, exhibiting imbalance in diversification among lineages and slowdowns in the rate of lineage accumulation through time. Such departures have led to a widespread perception that ecological differences among species or adaptation and subsequent niche filling are required to explain patterns of diversification. However, a key element missing from models of diversification is the geographical context of speciation and extinction.

The environmental limits to geographic range expansion in birds.

The environmental factors limiting species' ranges across broad geographic and taxonomic scales are central to questions regarding the geographic variation in biodiversity and impacts of environmental change. However, our understanding remains relatively limited owing to the small-scale, correlative nature of most previous analyses. In this study, we provide a global test of the environmental determinants of range limits in birds, using both stochastic and environmentally deterministic models of range expansion to simulate spatial patterns in the shape of species' distributions.

Global biogeography and ecology of body size in birds.

In 1847, Karl Bergmann proposed that temperature gradients are the key to understanding geographic variation in the body sizes of warm-blooded animals. Yet both the geographic patterns of body-size variation and their underlying mechanisms remain controversial. Here, we conduct the first assemblage-level global examination of 'Bergmann's rule' within an entire animal class.

4000 years of phenotypic change in an island bird: heterogeneity of selection over three microevolutionary timescales.

Pronounced phenotypic shifts in island populations are typically attributed to natural selection, but reconstructing heterogeneity in long-term selective regimes remains a challenge. We examined a scenario of divergence proposed for species colonizing a new environment, involving directional selection with a rapid shift to a new optimum and subsequent stabilization. We provide some of the first empirical evidence for this model of evolution using morphological data from three timescales in an island bird, Zosterops lateralis chlorocephalus.

Sympatric speciation in birds is rare: insights from range data and simulations.

Sympatric speciation is now accepted as theoretically plausible and a likely explanation for divergence in a handful of taxa, but its contribution to large-scale patterns of speciation remains contentious. A major problem is that it is difficult to differentiate between alternate scenarios of geographic speciation when species ranges have shifted substantially in the past. Previous studies have searched for a signal of the geographic mode of speciation by testing for a correlation between time since speciation and range overlap.

Pedigree-free animal models: the relatedness matrix reloaded.

Animal models typically require a known genetic pedigree to estimate quantitative genetic parameters. Here we test whether animal models can alternatively be based on estimates of relatedness derived entirely from molecular marker data. Our case study is the morphology of a wild bird population, for which we report estimates of the genetic variance-covariance matrices (G) of six morphological traits using three methods: the traditional animal model; a molecular marker-based approach to estimate heritability based on Ritland's pairwise regression method; and a new approach using a molecular genealogy arranged in a relatedness matrix (R) to replace the pedigree in an animal model.

Spatial turnover in the global avifauna.

Despite its wide implications for many ecological issues, the global pattern of spatial turnover in the occurrence of species has been little studied, unlike the global pattern of species richness. Here, using a database on the breeding distributions of birds, we present the first global maps of variation in spatial turnover for an entire taxonomic class, a pattern that has to date remained largely a matter of conjecture, based on theoretical expectations and extrapolation of inconsistent patterns from different biogeographic realms. We use these maps to test four predictions from niche theory as to the form that this variation should take, namely that turnover should increase with species richness, towards lower latitudes, and with the steepness of environmental gradients and that variation in turnover is determined principally by rare (restricted) species.

Biogeographical basis of recent phenotypic divergence among birds: a global study of subspecies richness.

Theory predicts that biogeographic factors should play a central role in promoting population divergence and speciation. Previous empirical studies into biogeography and diversification have been relatively restricted in terms of the geographical area, phylogenetic scope, and the range of biogeographic factors considered. Here we present a global analysis of allopatric phenotypic divergence (measured as subspecies richness) across more than 9600 bird species.

Topography, energy and the global distribution of bird species richness.

A major goal of ecology is to determine the causes of the latitudinal gradient in global distribution of species richness. Current evidence points to either energy availability or habitat heterogeneity as the most likely environmental drivers in terrestrial systems, but their relative importance is controversial in the absence of analyses of global (rather than continental or regional) extent. Here we use data on the global distribution of extant continental and continental island bird species to test the explanatory power of energy availability and habitat heterogeneity while simultaneously addressing issues of spatial resolution, spatial autocorrelation, geometric constraints upon species' range dynamics, and the impact of human populations and historical glacial ice-cover.

Energy, range dynamics and global species richness patterns: reconciling mid-domain effects and environmental determinants of avian diversity.

Spatial patterns of species richness follow climatic and environmental variation, but could reflect random dynamics of species ranges (the mid-domain effect, MDE). Using data on the global distribution of birds, we compared predictions based on energy availability (actual evapotranspiration, AET, the best single correlate of avian richness) with those of range dynamics models. MDE operating within the global terrestrial area provides a poor prediction of richness variation, but if it operates separately within traditional biogeographic realms, it explains more global variation in richness than AET.

Global distribution and conservation of rare and threatened vertebrates.

Global conservation strategies commonly assume that different taxonomic groups show congruent geographical patterns of diversity, and that the distribution of extinction-prone species in one group can therefore act as a surrogate for vulnerable species in other groups when conservation decisions are being made. The validity of these assumptions remains unclear, however, because previous tests have been limited in both geographical and taxonomic extent. Here we use a database on the global distribution of 19,349 living bird, mammal and amphibian species to show that, although the distribution of overall species richness is very similar among these groups, congruence in the distribution of rare and threatened species is markedly lower.

Human impacts and the global distribution of extinction risk.

Understanding the global geographical distribution of extinction risk is a key challenge in conservation biology. It remains controversial, however, to what extent areas become threat hotspots simply because of high human impacts or due to predisposing ecological conditions. Limits to the taxonomic and geographical extent, resolution and quality of previously available data have precluded a full global assessment of the relative roles of these factors.

Ecology predicts large-scale patterns of phylogenetic diversification in birds.

One of the most striking patterns in evolutionary biology is that clades may differ greatly in the number of species they contain. Numerous hypotheses have been put forward to explain this phenomenon, and several have been tested using phylogenetic methods. Remarkably, however, all such tests performed to date have been characterized by modest explanatory power, which has generated an interest in explanations stressing the importance of random processes.

Intake rates and the functional response in shorebirds (Charadriiformes) eating macro-invertebrates.

As field determinations take much effort, it would be useful to be able to predict easily the coefficients describing the functional response of free-living predators, the function relating food intake rate to the abundance of food organisms in the environment. As a means easily to parameterise an individual-based model of shorebird Charadriiformes populations, we attempted this for shorebirds eating macro-invertebrates. Intake rate is measured as the ash-free dry mass (AFDM) per second of active foraging; i.

Where is behavioural ecology going?

Since the 1990s, behavioural ecologists have largely abandoned some traditional areas of interest, such as optimal foraging, but many long-standing challenges remain. Moreover, the core strengths of behavioural ecology, including the use of simple adaptive models to investigate complex biological phenomena, have now been applied to new puzzles outside behaviour. But this strategy comes at a cost.

Direct versus indirect sexual selection: genetic basis of colour, size and recruitment in a wild bird.

Indirect and direct models of sexual selection make different predictions regarding the quantitative genetic relationships between sexual ornaments and fitness. Indirect models predict that ornaments should have a high heritability and that strong positive genetic covariance should exist between fitness and the ornament. Direct models, on the other hand, make no such assumptions about the level of genetic variance in fitness and the ornament, and are therefore likely to be more important when environmental sources of variation are large.

Global patterns of geographic range size in birds.

Large-scale patterns of spatial variation in species geographic range size are central to many fundamental questions in macroecology and conservation biology. However, the global nature of these patterns has remained contentious, since previous studies have been geographically restricted and/or based on small taxonomic groups. Here, using a database on the breeding distributions of birds, we report the first (to our knowledge) global maps of variation in species range sizes for an entire taxonomic class.

The comparative method in conservation biology.

The phylogenetic comparative approach is a statistical method for analyzing correlations between traits across species. Whilst it has revolutionized evolutionary biology, can it work for conservation biology? Although it is correlative, advocates of the comparative method hope that it will reveal general mechanisms in conservation, provide shortcuts for prioritizing conservation research, and enable us to predict which species will experience (or create) problems in the future. Here, we ask whether these stated management goals are being achieved.

Are subspecies useful in evolutionary and conservation biology?

The taxonomic rank of subspecies remains highly contentious, largely because traditional subspecies boundaries have sometimes been contradicted by molecular phylogenetic data. The most complete meta-analysis to date, for instance, found that only 3% of traditional avian subspecies represented distinct phylogenetic lineages. However, the global generality of this phenomenon remains unclear due to this previous study's narrow geographic focus on continental Nearctic and Palearctic subspecies.

Genetic covariance between indices of body condition and immunocompetence in a passerine bird.

Background: Condition-dependence is a ubiquitous feature of animal life histories and has important implications for both natural and sexual selection. Mate choice, for instance, is typically based on condition-dependent signals. Theory predicts that one reason why condition-dependent signals may be special is that they allow females to scan for genes that confer high parasite resistance.