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Environmental conditions play a major role in shaping the spatial distributions of pathogens, which in turn can drive local adaptation and divergence in host genetic diversity. Haemosporidians, such as Plasmodium (malaria), are a strong selective force, impacting survival and fitness of hosts, with geographic distributions largely determined by habitat suitability for their insect vectors. Here, we have tested whether patterns of fine‐scale local adaptation to malaria are replicated across discrete, ecologically differing island populations of Berthelot's pipits Anthus berthelotii. We sequenced TLR4, an innate immunity gene that is potentially under positive selection in Berthelot's pipits, and two SNPs previously identified as being associated with malaria infection in a genome‐wide association study (GWAS) in Berthelot's pipits in the Canary Islands. We determined the environmental predictors of malaria infection, using these to estimate variation in malaria risk on Porto Santo, and found some congruence with previously identified environmental risk factors on Tenerife. We also found a negative association between malaria infection and a TLR4 variant in Tenerife. In contrast, one of the GWAS SNPs showed an association with malaria risk in Porto Santo, but in the opposite direction to that found in the Canary Islands GWAS. Together, these findings suggest that disease‐driven local adaptation may be an important factor in shaping variation among island populations., We have investigated patterns of fine‐scale local adaptation to malaria between two ecologically divergent populations of an island bird. Our results found contrasting associations with malaria infection at candidate immune loci between the islands, suggesting that disease‐driven local adaptation may be an important factor in shaping variation among island populations.

Understanding the spatial scale at which selection acts upon adaptive genetic variation in natural populations is fundamental to our understanding of evolutionary ecology, and has important ramifications for conservation. The environmental factors to which individuals of a population are exposed can vary at fine spatial scales, potentially generating localized patterns of adaptation. Here, we compared patterns of neutral and major histocompatibility complex (MHC) variation within an island population of Berthelot's pipit (Anthus berthelotii) to assess whether landscape-level differences in pathogen-mediated selection generate fine-scale spatial structuring in these immune genes. Specifically, we tested for spatial associations between the distribution of avian malaria, and the factors previously shown to influence that distribution, and MHC variation within resident individuals. Although we found no overall genetic structure across the population for either neutral or MHC loci, we did find localized associations between environmental factors and MHC variation. One MHC class I allele (ANBE48) was directly associated with malaria infection risk, while the presence of the ANBE48 and ANBE38 alleles within individuals correlated (positively and negatively, respectively) with distance to the nearest poultry farm, an anthropogenic factor previously shown to be an important determinant of disease distribution in the study population. Our findings highlight the importance of considering small spatial scales when studying the patterns and processes involved in evolution at adaptive loci.

Island species provide excellent models for investigating how selection and drift operate in wild populations, and for determining how these processes act to influence local adaptation and speciation. Here, we examine the role of selection and drift in shaping genomic and phenotypic variation across recently separated populations of Berthelot's pipit (Anthus berthelotii), a passerine bird endemic to three archipelagos in the Atlantic. We first characterized genetic diversity and population structuring that supported previous inferences of a history of recent colonizations and bottlenecks. We then tested for regions of the genome associated with the ecologically important traits of bill length and malaria infection, both of which vary substantially across populations in this species. We identified a SNP associated with variation in bill length among individuals, islands, and archipelagos; patterns of variation at this SNP suggest that both phenotypic and genotypic variation in bill length is largely shaped by founder effects. Malaria was associated with SNPs near/within genes involved in the immune response, but this relationship was not consistent among archipelagos, supporting the view that disease resistance is complex and rapidly evolving. Although we found little evidence for divergent selection at candidate loci for bill length and malaria resistance, genome scan analyses pointed to several genes related to immunity and metabolism as having important roles in divergence and adaptation. Our findings highlight the utility and challenges involved with combining association mapping and population genetic analysis in nonequilibrium populations, to disentangle the effects of drift and selection on shaping genotypes and phenotypes.

How the environment influences the transmission and prevalence of disease in a population of hosts is a key aspect of disease ecology. The role that environmental factors play in host-pathogen systems has been well studied at large scales, that is, differences in pathogen pressures among separate populations of hosts or across land masses. However, despite considerable understanding of how environmental conditions vary at fine spatial scales, the effect of these parameters on host-pathogen dynamics at such scales has been largely overlooked. Here, we used a combination of molecular screening and GIS-based analysis to investigate how environmental factors determine the distribution of malaria across the landscape in a population of Berthelot's pipit (Anthus berthelotii, Bolle 1862) on the island of Tenerife (Canary Islands, Spain) using spatially explicit models that account for spatial autocorrelation. Minimum temperature of the coldest month was found to be the most important predictor of malaria infection at the landscape scale across this population. Additionally, anthropogenic factors such as distance to artificial water reservoirs and distance to poultry farms were important predictors of malaria. A model including these factors, and the interaction between distance to artificial water reservoirs and minimum temperature, best explained the distribution of malaria infection in this system. These results suggest that levels of malaria infection in this endemic species may be artificially elevated by the impact of humans. Studies such as the one described here improve our understanding of how environmental factors, and their heterogeneity, affect the distribution of pathogens within wild populations. The results demonstrate the importance of measuring fine-scale variation - and not just regional effects - to understand how environmental variation can influence wildlife diseases. Such understanding is important for predicting the future spread and impact of disease and may help inform disease management programmes as well as the conservation of specific host species.

Discerning the relative roles of adaptive and non-adaptive processes in generating differences among populations and species, as well as how these processes interact, are fundamental aims in biology. Both genetic and phenotypic divergence across populations can be the product of limited dispersal and gradual genetic drift across populations (isolation by distance), of colonisation history and founder effects (isolation by colonisation) or of adaptation to different environments preventing migration between populations (isolation by adaptation). Here we attempt to differentiate between these processes using island populations of Berthelot's pipit (Anthus berthelotii), a passerine bird endemic to three Atlantic archipelagos. Using microsatellite markers and approximate Bayesian computation, we reveal that the northwards colonisation of this species ca 8,500 years ago resulted in genetic bottlenecks in the colonised archipelagos. We then show that high levels of genetic structure exist across archipelagos, and that these are consistent with a pattern of isolation by colonisation, but not with isolation by distance or adaptation. Finally, we show that substantial morphological divergence also exists and that this is strongly concordant with patterns of genetic structure and bottleneck history, but not with environmental differences or geographic distance. Overall our data suggest that founder effects are responsible for both genetic and phenotypic changes across archipelagos. Our findings provide a rare example of how founder effects can persist over evolutionary timescales, and suggest that they may play an important role in the early stages of speciation. This article is protected by copyright. All rights reserved.

Pathogens can exert strong selective forces upon host populations. However, before we can make any predictions about the consequences of pathogen-mediated selection, we first need to determine whether patterns of pathogen distribution are consistent over spatiotemporal scales. We used molecular techniques to screen for a variety of blood pathogens (avian malaria, pox and trypanosomes) over a three-year time period across 13 island populations of the Berthelot's pipit (Anthus berthelotii). This species has only recently dispersed across its range in the North Atlantic, with little subsequent migration, providing an ideal opportunity to examine the causes and effects of pathogenic infection in populations in the early stages of differentiation. We screened 832 individuals, and identified two strains of Plasmodium, four strains of Leucocytozoon, and one pox strain. We found strong differences in pathogen prevalence across populations, ranging from 0 to 65%, and while some fluctuations in prevalence occurred, these differences were largely stable over the time period studied. Smaller, more isolated islands harboured fewer pathogen strains than larger, less isolated islands, indicating that at the population level, colonization and extinction play an important role in determining pathogen distribution. Individual-level analyses confirmed the island effect, and also revealed a positive association between Plasmodium and pox infection, which could have arisen due to dual transmission of the pathogens by the same vectors, or because one pathogen lowers resistance to the other. Our findings, combined with an effect of infection on host body condition, suggest that Berthelot's pipits are subject to different levels of pathogen-mediated selection both across and within populations, and that these selective pressures are consistent over time., Grant from the Natural Environment Research Council to DSR and LGS, and a Spanish fellowship (Ramón y Cajal program) to JCI.

The Portuguese island of Selvagem Grande (Great Salvage) in Macaronesia is an important seabird breeding station in the eastern Atlantic. Significant populations of Cory's shearwater Calonectris diomedea (Scopoli, 1769), Bulwer's petrel Bulweria bulweria (Jardine & Selby, 1828) and little shearwater Puffinus assimilis baroli (Bonaparte, 1857) are present, and white-faced storm-petrel Pelagodroma marina (Latham, 1790) and Madeiran storm-petrel Oceanodroma castro (Harcourt, 1851) populations are of global significance. Selvagem Grande also provides diverse habitats for an extensive flora, including 11 endemic species. The 270-ha island was also inhabited by two alien invasive mammals: the European rabbit Oryctolagus cuniculus (Linnaeus, 1758) and the house mouse Mus musculus (Linnaeus, 1758). Both are known to have had adverse impacts on breeding seabirds and island vegetation. In 2002, the Natural Park of Madeira conducted a program using brodifacoum bait formulations aimed at rabbit and mouse eradication. Approximately 17 000 individual baiting points were established on a 12.5 × 12.5 m grid. Baits were also applied by hand "seeding" on steep slopes and cliffs where bait stations could not be placed. Rabbits were removed after a month. However, mice persisted for considerably longer and strategic bait applications against them continued for a further six months. Subsequent assessments by trapping, bait takes and systematic observation of signs over three years, has confirmed the removal of both alien invasive species. This paper presents information on these operations, on measures adopted to mitigate adverse impacts of the eradication program on important vertebrate non-target species, including Berthelot's pipit Anthus berthelotii Bolle, 1862 and a species of gecko Tarentola bischoffi Joger, 1984 and on the initial response of the island's ecosystem to the eradication of rabbits and mice.

The phylogenetic relationships of Berthelot's Pipit Anthus berthelotii, which is endemic to three groups of North Atlantic islands, have puzzled ornithologists for more than a century. A total of 1041 base pair cytochrome b mitochondrial DNA sequences from Berthelot's Pipit are compared with homologous sequences from the Tawny Pipit Anthus campestris, Richard's Pipit Anthus novaeseelandiae, the Meadow Pipit Anthus pratensis, the Red-breasted Pipit Anthus cervinus, the Tree Pipit Anthus trivialis, Rock and Water Pipits Anthus spinoletta and the White Wagtail Motacilla alba. In the resulting phytogeny, the sister taxon of Berthelot's Pipit is unambiguously the Tawny Pipit, with Richard's Pipit forming a deeper branch on the same clade. Sequences of a Danish Rock Pipit and a Swiss Water Pipit support a close relationship between these two species, but more comprehensive studies of intra- and interpopulation variation are required before considering their taxonomic ranking. Some preliminary inferences are made regarding phylogenetic tendencies in the genus Anthus.

We describe the density, breeding and foraging ecology of the Berthelot's Pipit ( Anthus berthelotii ), an endemic passerine to the Atlantic islands, in the semi-arid coastal scrub of Tenerife. Furthermore, we analyse the effects of temperature and rainfall in the onset of reproduction and the behaviour (nest site and foraging site selection). The average density of the Pipit (using DISTANCE methodology) in the semi-arid coastal scrub was 7.1 birds 10ha –1 , and the overall density estimate in grassland was 3.3 birds 10ha –1 . The Pipit bred early (mean average first-egg laying date 12 February) and in response to rainfall (but not temperature). By the Mayfield method, the probability of the nests surviving the egg stage was 0.77 and of and the nests surviving the chick stage 0.67 — assuming an incubation period of 13 days and a chick stage of 12.5 days — based on the European average for the similar-sized Meadow Pipit Anthus pratensis . Overall nest survival pooling stages were 0.51. The Pipits had a low clutch size (3.3 eggs, range of 2–4). Nest damage by heavy rainstorms was the major cause of nest failures (three out of five failures). The Pipits nested preferentially in grass with relatively low densities of Euphorbia balsamifera bushes. Birds selected grassy areas as their main foraging site but also preferred to forage on large rocks during nesting: caterpillars were the main food items (14 out of 17 prey captures). Ostrich 2007, 78(3): 583–589

The fauna of oceanic islands provide exceptional models with which to examine patterns of dispersal, isolation and diversification, from incipient speciation to species level radiations. Here, we investigate recent differentiation and microevolutionary change in Berthelot's pipit (Anthus berthelotii), an endemic bird species inhabiting three Atlantic archipelagos. Mitochondrial DNA sequence data and microsatellite markers were used to deduce probable colonization pathway, genetic differentiation, and gene flow among the 12 island populations. Phenotypic differentiation was investigated based on eight biologically important morphological traits. We found little mitochondrial DNA variability, with only one and four haplotypes for the control region and cytochrome b, respectively. However, microsatellite data indicated moderate population differentiation (FST = 0.069) between the three archipelagos that were identified as genetically distinct units with limited gene flow. Both results, combined with the estimated time of divergence (2.5 millions years ago) from the Anthus campestris (the sister species), suggest that this species has only recently dispersed throughout these islands. The genetic relationships, patterns of allelic richness and exclusive alleles among populations suggest the species originally colonized the Canary Islands and only later spread from there to the Madeiran archipelago and Selvagen Islands. Differentiation has also occurred within archipelagos, although to a lesser degree. Gene flow was observed more among the eastern and central islands of the Canaries than between these and the western islands or the Madeiran Islands. Morphological differences were also more important between than within archipelagos. Concordance between morphological and genetic differentiation provided ambiguous results suggesting that genetic drift alone was not sufficient to explain phenotypic differentiation. The observed genetic and morphological differences may therefore be the result of differing patterns of selection pressures between populations, with Berthelot's pipit undergoing a process of incipient differentiation.

Understanding the relative role of different evolutionary forces in shaping the level and distribution of functional genetic diversity among natural populations is a key issue in evolutionary and conservation biology. To do so accurately genetic data must be analyzed in conjunction with an unambiguous understanding of the historical processes that have acted upon the populations. Here we focused on diversity at toll-like receptor (TLR) loci, which play a key role in the vertebrate innate immune system and, therefore, are expected to be under pathogen-mediated selection. We assessed TLR variation within and among 13 island populations (grouped into three archipelagos) of Berthelot's pipit, Anthus berthelotii, for which detailed population history has previously been ascertained. We also compared the variation observed with that found in its widespread sister species, the tawny pipit, Anthus campestris. We found strong evidence for positive selection at specific codons in TLR1LA, TLR3 and TLR4. Despite this, we found that at the allele frequency level, demographic history has played the major role in shaping patterns of TLR variation in Berthelot's pipit. Levels of diversity and differentiation within and across archipelagos at all TLR loci corresponded very closely with neutral microsatellite variation, and with the severity of the bottlenecks that occurred during colonization. Our study shows that despite the importance of TLRs in combating pathogens, demography can be the main driver of immune gene variation within and across populations, resulting in patterns of functional variation that can persist over evolutionary timescales. This article is protected by copyright. All rights reserved.

We identified microsatellite sequences of potential utility in the house sparrow (Passer domesticus) and assigned their predicted genome locations. These sequences included newly isolated house sparrow loci, which we fully characterized. Many of the newly isolated loci were polymorphic in two other species of Passeridae: Berthelot’s pipit Anthus berthelotii and zebra finch Taeniopygia guttata. In total, we identified 179 microsatellite markers that were either isolated directly from, or are of known utility in, the house sparrow. Sixty-seven of these markers were designed from unique sequences that we isolated from a house sparrow genomic library. These new markers were combined with 36 house sparrow markers isolated by other studies and 76 markers isolated from other passerine species but known to be polymorphic in the house sparrow. We utilized sequence homology to assign chromosomal locations for these loci in the assembled zebra finch genome. One hundred and thirty-four loci were assigned to 25 different autosomes and eight loci to the Z chromosome. Examination of the genotypes of known-sex house sparrows for 37 of the new loci revealed a W-linked locus and an additional Z-linked locus. Locus Pdol2, previously reported as autosomal, was found to be Z-linked. These loci enable the creation of powerful and cost-effective house sparrow multiplex primer sets for population and parentage studies. They can be used to create a house sparrow linkage map and will aid the identification of quantitative trait loci in passerine species.

Between January 2002 and November 2003, 50% (n = 395) of short-toed larks (Calandrella rufescens) and 28% (n = 139) of Berthelot's pipits (Anthus berthelotti) examined on the islands of Fuerteventura and Lanzarote, Canary Islands, had gross lesions compatible with avian pox. However, Spanish sparrows (Passer hispaniolensis, n = 128) and trumpeter finches (Bucanetes githagineus, n = 228), which inhabit the same steppe habitats associated with goat husbandry, did not have poxlike lesions. Histopathology and electron microscopy confirmed poxvirus in the lesions, whereas serology using standard, fowl poxvirus- and pigeon poxvirus-based diagnostic agar gel immunodiffusion techniques was negative, likely because of the limited (74.6% pipit; 74.9% lark) similarity between the viruses in our species and fowlpox virus on which the serologic tests rely. On the basis of polymerase chain reaction analyses, the virus isolated from dried lesions of C. rufescens has 80.5% similarity with the virus isolated from A. berthelotti and 91.3% similarity with canarypox, whereas A. berthelotti poxvirus has only 80% similarity with canarypox. We have two distinct and possibly new avian poxviruses. Both poultry and the wild birds on the farms were heavily infested by fleas, which may have acted as vectors in transmission of poxvirus. Disease prevalence in these Canary Island passerines is higher than that described in song birds in Hawaii that are now threatened, endangered, or extinct. Environmental and biological factors contributing to increased disease susceptibility of these isolated populations must be investigated.

Berthelot’s Pipit Anthus berthelotii Bolle, 1862a, an endemic to Macaronesia (see e.g. Garcia-Talavera Casanas 1999 for this term), is closely related to the widespread Palearctic Anthus campestris (Linnaeus, 1758) (Alstrom & Mild 1993; Arctander et al. 1996; Illera et al. 2007; Voelker 1999a,b). Carl August Bolle (1821–1909), German traveler and naturalist, visited Macaronesia in 1851–1853 and again in 1856–1857 (Salinger & Strehlow 1891; see also Bolle 1854a,b, 1857, 1858a,b, 1862a,b). He described Anthus berthelotii in two papers (Bolle 1862a,b), providing a morphological description of the species and referring to several authors who, he believed, recorded the same species under different names. However, he did not mention specific specimen(s) or collection(s) at which he had studied Anthus specimens. Thus, we restudied the original description of Anthus berthelotii to identify its type series.