The Evolution of Larger Size in High Altitude Drosophila melanogaster has a Variable Genetic Architecture

Important uncertainties persist regarding the genetic architecture of adaptive trait evolution in natural populations, including the number of genetic variants involved, whether they are drawn from standing genetic variation, and whether directional selection drives them to complete fixation. Here, we take advantage of a unique natural population of Drosophila melanogaster from the Ethiopian highlands, which has evolved larger body size than any other known population of this species. We apply a bulk segregant quantitative trait locus (QTL) mapping approach to four unique crosses between highland Ethiopian and lowland Zambian populations for both thorax length and wing length. Results indicated a persistently variable genetic basis for these evolved traits (with largely distinct sets of QTLs for each cross), and at least a moderately polygenic architecture with relatively strong effects present. We complemented these mapping experiments with population genetic analyses of QTL regions and gene ontology enrichment analysis, generating strong hypotheses for specific genes and functional processes that may have contributed to these adaptive trait changes. Finally, we find that the genetic architectures our QTL mapping results for size traits mirror those from similar experiments on other recently-evolved traits in this species. Collectively, these studies suggest a recurring pattern of polygenic adaptation in this species, in which causative variants do not approach fixation and moderately strong effect loci are present.

The Evolution of Larger Size in High Altitude Drosophila melanogaster has a Polymorphic Genetic Architecture

Important uncertainties persist regarding the genetic architecture of adaptive trait evolution in natural populations, including the number of genetic variants involved, whether they are drawn from standing genetic variation, and whether directional selection drives them to complete fixation. Here, we take advantage of a unique natural population of Drosophila melanogaster from the Ethiopian highlands, which has evolved larger body size than any other known population of this species. We apply a bulk segregant quantitative trait locus (QTL) mapping approach to four unique crosses between highland Ethiopian and lowland Zambian populations for both thorax length and wing length. Results indicated a persistently variable genetic basis for these evolved traits (with largely distinct sets of QTLs for each cross), and at least a moderately polygenic architecture with relatively strong effects present. We complemented these mapping experiments with population genetic analyses of QTL regions and gene ontology enrichment analysis, generating strong hypotheses for specific genes and functional processes that may have contributed to these adaptive trait changes. Finally, we find that the genetic architectures our QTL mapping results for size traits mirror those from similar experiments on other recently-evolved traits in this species. Collectively, these studies suggest a recurring pattern of polygenic adaptation in this species, in which causative variants do not approach fixation and moderately strong effect loci are present.

The taxonomy of two uncultivated fungal mammalian pathogens is revealed through phylogeny and population genetic analyses

Ever since the uncultivated South American fungal pathogen Lacazia loboi was first described 90 years ago, its etiology and evolutionary traits have been at the center of endless controversies. This pathogen infects the skin of humans and as long believed, dolphin skin. However, recent DNA analyses of infected dolphins placed its DNA sequences within Paracoccidioides species. This came as a surprise and suggested the human and dolphin pathogens may be different species. In this study, population genetic analyses of DNA from four infected dolphins grouped this pathogen in a monophyletic cluster sister to P. americana and to the other Paracoccidioides species. Based on the results we have emended the taxonomy of the dolphin pathogen as Paracoccidioides cetii and P. loboi the one infecting human. Our data warn that phylogenetic analysis of available taxa without the inclusion of unusual members may provide incomplete information for the accurate classification of anomalous species.

Cuticular hydrocarbons on old museum specimens of the spiny mason wasp, Odynerus spinipes (Hymenoptera: Vespidae: Eumeninae), shed light on the distribution and on regional frequencies of distinct chemotypes

The mason wasp Odynerus spinipes shows an exceptional case of intrasexual cuticular hydrocarbon (CHC) profile dimorphism. Females of this species display one of two CHC profiles (chemotypes) that differ qualitatively and quantitatively from each other. The ratio of the two chemotypes was previously shown to be close to 1:1 at three sites in Southern Germany, which might not be representative given the Palearctic distribution of the species. To infer the frequency of the two chemotypes across the entire distributional range of the species, we analyzed with GC–MS the CHC profile of 1042 dry-mounted specimens stored in private and museum collections. We complemented our sampling by including 324 samples collected and preserved specifically for studying their CHCs. We were capable of reliably identifying the chemotypes in 91% of dry-mounted samples, some of which collected almost 200 years ago. We found both chemotypes to occur in the Far East, the presumed glacial refuge of the species, and their frequency to differ considerably between sites and geographic regions. The geographic structure in the chemotype frequencies could be the result of differential selection regimes and/or different dispersal routes during the colonization of the Western Palearctic. The presented data pave the route for disentangling these factors by providing information where to geographically sample O. spinipes for population genetic analyses. They also form the much-needed basis for future studies aiming to understand the evolutionary and geographic origin as well as the genetics of the astounding CHC profile dimorphism that O. spinipes females exhibit.

Population Genetic Analyses of Botrytis cinerea Isolates From Michigan Vineyards Using a High-Throughput Marker System Approach

As sequencing costs continue to decrease, new tools are being developed for assessing pathogen diversity and population structure. Traditional marker types, such as microsatellites, are often more cost effective than single-nucleotide polymorphism (SNP) panels when working with small numbers of individuals, but may not allow for fine scale evaluation of low or moderate structure in populations. Botrytis cinerea is a necrotrophic plant pathogen with high genetic variability that can infect more than 200 plant species worldwide. A panel of 52 amplicons were sequenced for 82 isolates collected from four Michigan vineyards representing 2 years of collection and varying fungicide resistance. A panel of nine microsatellite markers previously described was also tested across 74 isolates from the same population. A microsatellite and SNP marker analysis of B. cinerea populations was performed to assess the genetic diversity and population structure of Michigan vineyards, and the results from both marker types were compared. Both methods were able to detect population structure associated with resistance to the individual fungicides thiabendazole and boscalid, and multiple fungicide resistance (MFR). Microsatellites were also able to differentiate population structure associated with another fungicide, fluopyram, while SNPs were able to additionally differentiate structure based on year. For both methods, AMOVA results were similar, with microsatellite results explaining a smaller portion of the variation compared with the SNP results. The SNP-based markers presented here were able to successfully differentiate population structure similar to microsatellite results. These SNP markers represent new tools to discriminate B. cinerea isolates within closely related populations using multiple targeted sequences.

Review of Uvarovistia (Orthoptera: Tettigoniidae; Tettigoniinae): genetic data indicate a new cryptic species, Uvarovistia munzurensis sp.n.

Genus Uvarovistia ranged along the Zagros Mountain belt. We presented first genetic data from three species of the genus and a taxonomic rectification indicated by these data. Sequences of three mitochondrial and two nuclear gene segments were obtained from different populations. Phylogenetic and automatic species delimitation analyses consistently suggested three distinct phylogroups as U. zebra, U. satunini and the third a new species, U. munzurensis Uluar & Yahyaoğlu sp. n. Time estimation and population genetic analyses supported consistent results. The following conclusions were reached: (i) five species in the genus constitute two distinct species groups named as Zebra Group and Satunini Group, (ii) data suggest intra generic relationships as U. zebra + ((U. satunini + U. munzurensis) + (U. bakhtiara +U. iraka)), (iii) molecular clock estimations indicated a deep divergence time and no gene flow between U. satunini and U. munzurensis, (iv) although these two species cannot be clearly distinguished by morphology, range of U. munzurensis seems to be isolated from other by lowlands of Euphrates Valley, and (v) age of generic ancestor is around five million years a time corresponding to connection of Anatolian and Zagros plates, and genus radiated along Zagros belt after dispersal of ancestral stock here.

Unravelling the Habenaria repens (Orchidaceae) complex in Brazil: a biosystematic and molecular phylogenetic approach

Habenaria repens (Orchidaceae) represents a species complex distributed from the southern USA to northern Argentina, including several morphological variants, here referred to as morphotypes. To investigate and clarify the morphological and genetic relationships between these morphotypes and resolve the taxonomy of the complex, we applied a biosystematic multi-population approach using molecular phylogenetic, morphometric and population genetics analyses in the group. We sampled 31 (phylogenetic analyses) and 20 (morphometric and microsatellite analyses) populations of Habenaria aranifera and H. repens from Brazil and the USA, including six morphotypes of H. repens. Bayesian and maximum parsimony phylogenetic analyses of nuclear ribosomal (ITS and ETS) and plastid (matK, trnK and rps16-trnK) markers revealed that the complex is polyphyletic, subdivided into three distantly related clades. Population genetic analyses using microsatellites showed a remarkably similar structure to the phylogenetic analyses, but both were different from the morphometric analyses of floral characters, indicating cases of diversification and convergence, probably due to pollination processes. Habenaria aranifera is embedded in a paraphyletic and polymorphic H. repens with a broad geographical distribution and other attributes of an ochlospecies, probably constituting a progenitor–derivative pair. Our results support the recognition of H. aranifera, H. repens and three or four new species.