BackgroundAvian trichomonosis is known as a widespread disease in columbids and passerines, and recent findings have highlighted the pathogenic character of some lineages found in wild birds. Trichomonosis can affect wild bird populations including endangered species, as has been shown for Mauritian pink pigeons Nesoenas mayeri in Mauritius and suggested for European turtle doves Streptopelia turtur in the UK. However, the disease trichomonosis is caused only by pathogenic lineages of the parasite Trichomonas gallinae. Therefore, understanding the prevalence and distribution of both potentially pathogenic and non-pathogenic T. gallinae lineages in turtle doves and other columbids across Europe is relevant to estimate the potential impact of the disease on a continental scale.ResultsWe examined 281 samples from four wild columbid species for Trichomonas infection and determined the genetic lineages. The overall prevalence was 74%. There were significant differences between the species (P = 0.007). The highest prevalence was found in stock doves Columba oenas (86%, n = 79) followed by wood pigeons Columba palumbus (70%, n = 61) and turtle doves (67%, n = 65), while three of five collared doves Streptopelia decaocto (60%) were infected. We found seven different lineages, including four lineages present in columbids in the UK, one lineage already described from Spain and three new lineages, one of those found in a single turtle dove migrating through Italy and another one found in a breeding stock dove. Stock doves from Germany and collared doves from Malta were infected with a potentially pathogenic lineage (lineage A/B), which is known to cause lesions and mortality in columbids, raptors and finches.ConclusionsGenerally, turtle doves showed high prevalence of Trichomonas infection. Furthermore, the potentially pathogenic lineage A/B (or genotype B according to previous literature) was found in a recovering stock dove population. Both findings are worrying for these columbid species due to the occasional epidemic character of trichomonosis, which can have severe negative effects on populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2170-0) contains supplementary material, which is available to authorized users.

Using immunolocalization of the mismatch-repair protein MLH1 in oocytes and spermatocytes of the Japanese quail and the zebra finch, we estimated the average amount of recombination in each sex of both species. In each case the number of MLH1 foci is statistically equivalent in males and females and the resulting sex-averaged map lengths are 2800 cM in the Japanese quail and 2275 cM in the zebra finch. In the Japanese quail the MLH1 foci are regularly distributed along the macrobivalents and recombination rates per Mb pair are somewhat lower compared to the chicken. In the zebra finch the MLH1 foci on the macrobivalents are substantially reduced in number relative to the Japanese quail and they show remarkable localization in both sexes. It is proposed that the lack of sex-dependent differences in recombination might be an extended feature among birds and that the different recombination patterns observed here reflect different controls of crossing over in spite of similarities regarding karyotypic asymmetry and DNA content. We discussed possible causes of the differences between birds and mammals, which show sex-dependent recombination differences.

BackgroundUnderstanding how past climatic oscillations have affected organismic evolution will help predict the impact that current climate change has on living organisms. The European turtle dove, Streptopelia turtur, is a warm-temperature adapted species and a long distance migrant that uses multiple flyways to move between Europe and Africa. Despite being abundant, it is categorized as vulnerable because of a long-term demographic decline. We studied the demographic history and population genetic structure of the European turtle dove using genomic data and mitochondrial DNA sequences from individuals sampled across Europe, and performing paleoclimatic niche modelling simulations.ResultsOverall our data suggest that this species is panmictic across Europe, and is not genetically structured across flyways. We found the genetic signatures of demographic fluctuations, inferring an effective population size (Ne) expansion that occurred between the late Pleistocene and early Holocene, followed by a decrease in the Ne that started between the mid Holocene and the present. Our niche modelling analyses suggest that the variations in the Ne are coincident with recent changes in the availability of suitable habitat.ConclusionsWe argue that the European turtle dove is prone to undergo demographic fluctuations, a trait that makes it sensitive to anthropogenic impacts, especially when its numbers are decreasing. Also, considering the lack of genetic structure, we suggest all populations across Europe are equally relevant for conservation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0817-7) contains supplementary material, which is available to authorized users.

57 Surprisingly, we found that species trees estimated from interspecific F ST provided better 58 approximations of mtDNA relationships among the studied species than those estimated using D C , 59even though F ST was more affected by null alleles. We observed a significantly non-linear second 60 order polynomial relationship between microsatellite and mtDNA distances. We propose that the loss 61 of linearity with increasing mtDNA distance stems from an increasing proportion of homoplastic allele 62 size classes that are identical in state, but not identical by descent. Therefore, despite high cross-63 species amplification success and high polymorphism among the closely related Pachyptila species, 64we caution against the use of microsatellites in phylogenetic inference among distantly related taxa.

The effects of global glaciations on the distribution of organisms is an essential element of many diversification models. However, the empirical evidence supporting this idea is mixed, in particular with respect to explaining tropical forest evolution. In the present study, we evaluated the impacts of range shifts associated with Pleistocene global glacial cycles on the evolution of tropical forests. In particular, we tested the predictions: (1) that population genetic structure increases with fragmentation variation between the present and the Last Glacial Maximum (LGM) and also (2) with geographical range instability; and (3) that genetic diversity increases with range stability and (4) decreases with fragmentation variation between periods. To address our predictions, we studied population genetic structures and modelled present and past distributions of 15 Atlantic Forest (AF) endemic birds. Afterwards, we evaluated the relationship of population genetic parameters with metrics of species range shifts between the present and the LGM. We found that geographical ranges of AF birds changed in concert with Pleistocene glacial cycles but, unexpectedly, our findings suggest the novel idea that ranges during glacial maxima were slightly larger on average, as well as equally fragmented and displaced from the interglacial ranges. Our findings suggest that range shifts over the late Pleistocene impacted on the diversification of forest organisms, although they did not show that those range shifts had a strong effect. We found that a combination of fragmentation variation across time, small current range size, and range stability increased population genetic structure. However, neither fragmentation, nor range stability affected genetic diversity. Our study showed that evolutionary responses to range shifts across AF birds have a high variance, which could explain the mixed support given by single‐species studies to the action of Pleistocene range shifts on population evolution.

Speciation through homoploid hybridization (HHS) is considered extremely rare in animals. This is mainly because the establishment of reproductive isolation as a product of hybridization is uncommon. Additionally, many traits are underpinned by polygeny and/or incomplete dominance, where the hybrid phenotype is an additive blend of parental characteristics. Phenotypically intermediate hybrids are usually at a fitness disadvantage compared with parental species and tend to vanish through backcrossing with parental population(s). It is therefore unknown whether the additive nature of hybrid traits in itself could lead successfully to HHS. Using a multi-marker genetic data set and a meta-analysis of diet and morphology, we investigated a potential case of HHS in the prions (Pachyptila spp.), seabirds distinguished by their bills, prey choice, and timing of breeding. Using approximate Bayesian computation, we show that the medium-billed Salvin’s prion (Pachyptila salvini) could be a hybrid between the narrow-billed Antarctic prion (Pachyptila desolata) and broad-billed prion (Pachyptila vittata). Remarkably, P. salvini’s intermediate bill width has given it a feeding advantage with respect to the other Pachyptila species, allowing it to consume a broader range of prey, potentially increasing its fitness. Available metadata showed that P. salvini is also intermediate in breeding phenology and, with no overlap in breeding times, it is effectively reproductively isolated from either parental species through allochrony. These results provide evidence for a case of HHS in nature, and show for the first time that additivity of divergent parental traits alone can lead directly to increased hybrid fitness and reproductive isolation.

Hypogeococcus pungens , a mealybug native of southern South America, is devastating native cacti in Puerto Rico and threatening cactus diversity in the Caribbean, and potentially in Central and North America. The taxonomic status of H . pungens is controversial since it has been reported feeding not only on Cactaceae but also on other plant families throughout its distribution range. However, in Australia, where the species had been exported from Argentina to control weedy American cacti, it was never found on host plants other than Cactaceae. These conflicting pieces of evidence not only cast doubt on the species identity that invaded Puerto Rico, but also have a negative impact on the search for natural enemies to be used in biological control programs against this pest. Here we present reproductive incompatibility and phylogenetic evidences that give support to the hypothesis that H . pungens is a species complex in which divergence appears to be driven by the host plants. The nuclear EF1α and 18S and the mitochondrial COI genes were used as markers to evaluate the phylogenetic relationships among H . pungens populations collected in Argentina, Australia and Puerto Rico feeding on Cactaceae and/or Amaranthaceae. Additionally, we conducted reciprocal crosses between mealybugs from both hosts. Species delimitation analysis revealed two well-supported putative species within H . pungens , one including mealybugs feeding on Amaranthaceae ( H . pungens sensu stricto ), and a new undescribed species using Cactaceae as hosts. Additionally, we found asymmetric reproductive incompatibility between these putative species suggesting recent reproductive isolation. The Bayesian species delimitation also suggested that the Australian mealybug population may derive from another undescribed species. Overall, the patterns of genetic differentiation may be interpreted as the result of recent speciation events prompted by host plant shifts. Finally, the finding of a single haplotype in the Puerto Rico population suggests only one invasive event. We still need to identify the geographical origin of the pest in order to enable the use of biological control to reduce the threat to cacti diversity in the Caribbean.

BackgroundIn seabirds, the extent of population genetic and phylogeographic structure varies extensively among species. Genetic structure is lacking in some species, but present in others despite the absence of obvious physical barriers (landmarks), suggesting that other mechanisms restrict gene flow. It has been proposed that the extent of genetic structure in seabirds is best explained by relative overlap in non-breeding distributions of birds from different populations. We used results from the analysis of microsatellite DNA variation and geolocation (tracking) data to test this hypothesis. We studied three small (130–200 g), very abundant, zooplanktivorous petrels (Procellariiformes, Aves), each sampled at two breeding populations that were widely separated (Atlantic and Indian Ocean sectors of the Southern Ocean) but differed in the degree of overlap in non-breeding distributions; the wintering areas of the two Antarctic prion (Pachyptila desolata) populations are separated by over 5000 km, whereas those of the blue petrels (Halobaena caerulea) and thin-billed prions (P. belcheri) show considerable overlap. Therefore, we expected the breeding populations of blue petrels and thin-billed prions to show high connectivity despite their geographical distance, and those of Antarctic prions to be genetically differentiated.ResultsMicrosatellite (at 18 loci) and cytochrome b sequence data suggested a lack of genetic structure in all three species. We thus found no relationship between genetic and spatial structure (relative overlap in non-breeding distributions) in these pelagic seabirds.ConclusionsIn line with other Southern Ocean taxa, geographic distance did not lead to genetic differences between widely spaced populations of Southern Ocean petrel species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-1008-x) contains supplementary material, which is available to authorized users.