Cold adaptation drives population genomic divergence in the ecological specialist, Drosophila montana

Funding: UK Natural Environment Research Council (Grant Number(s): NE/L501852/1, NE/P000592/1); Academy of Finland (GrantNumber(s): 267244, 268214, 322980), Ella ja Georg Ehrnroothin Säätiö.Detecting signatures of ecological adaptation in comparative genomics is challenging, but analysing population samples with characterised geographic distributions, such as clinal variation, can help identify genes showing covariation with important ecological variation. Here, we analysed patterns of geographic variation in the cold-adapted species Drosophila montana across phenotypes, genotypes and environmental conditions and tested for signatures of cold adaptation in population genomic divergence. We first derived the climatic variables associated with the geographic distribution of 24 populations across two continents to trace the scale of environmental variation experienced by the species, and measured variation in the cold tolerance of the flies of six populations from different geographic contexts. We then performed pooled whole genome sequencing of these six populations, and used Bayesian methods to identify SNPs where genetic differentiation is associated with both climatic variables and the population phenotypic measurements, while controlling for effects of demography and population structure. The top candidate SNPs were enriched on the X and fourth chromosomes, and they also lay near genes implicated in other studies of cold tolerance and population divergence in this species and its close relatives. We conclude that ecological adaptation has contributed to the divergence of D. montana populations throughout the genome and in particular on the X and fourth chromosomes, which also showed highest interpopulation FST. This study demonstrates that ecological selection can drive genomic divergence at different scales, from candidate genes to chromosome-wide effects.Publisher PDFPeer reviewe

Higgs-mass predictions in the MSSM and beyond

Predictions for the Higgs masses are a distinctive feature of supersymmetric extensions of the Standard Model, where they play a crucial role in constraining the parameter space. The discovery of a Higgs boson and the remarkably precise measurement of its mass at the LHC have spurred new efforts aimed at improving the accuracy of the theoretical predictions for the Higgs masses in supersymmetric models. The "Precision SUSY Higgs Mass Calculation Initiative" (KUTS) was launched in 2014 to provide a forum for discussions between the different groups involved in these efforts. This report aims to present a comprehensive overview of the current status of Higgs-mass calculations in supersymmetric models, to document the many advances that were achieved in recent years and were discussed during the KUTS meetings, and to outline the prospects for future improvements in these calculations

Acoustic preference functions and sexual selection on the male calling song in the grasshopper Chorthippus biguttulus

Klappert K, Reinhold K. Acoustic preference functions and sexual selection on the male calling song in the grasshopper Chorthippus biguttulus. Animal Behaviour 65. 2003;65(1):225-233

Factors affecting male song evolution in Drosophila montana

D. montana (a species of the D. virilis group) has spread over the northern hemisphere, populations from different areas showing both genetic and phenotypic divergence. The males of this species produce an elaborate courtship song, which plays a major role both in species recognition and in intraspecific mate choice. The genetic architecture and physical constraints, as well as the importance of the signal for species recognition, set boundaries within which this signal can vary. Within these limits, courtship song parameters may change, depending on the males' physical condition and on the environment they inhabit. Females are likely to affect song evolution by exerting directional selection toward higher carrier frequencies. Given this complexity, only a comprehensive, multidisciplinary approach, starting with traditional field observation and combining controlled behavioral experiments, biometric measurements, and sophisticated molecular techniques, has the potential of shedding light on the past history and the evolution of this signal, and, eventually, adding to our understanding of the mechanisms, functions, and outcomes of sexual selection in acoustic communication systems. (c) 2005, Elsevier Inc.</p

Immune defence, dispersal and local adaptation

To determine the influence of dispersal on the expression of immune traits, we conducted a reciprocal transfer experiment. Chorthippus biguttulus grasshoppers from two populations were released as juveniles into their native and transfer environments. After recapture as adults, we found that an immune trait, the amount of phagocytically active cells, was significantly reduced in the transfer environments. In contrast, adult body mass differed between the two habitats, but was not reduced in the transfer environments. The results suggest that dispersal to a new environment can reduce the expression of immune traits, while otherwise not influencing body condition. One reason for such an effect could be that the parasite community in the foreign environment might be relatively maladapted, which would lead to reduced demands for resource allocation to immune traits

The attractiveness fragment - AFLP analysis of local adaptation and sexual selection in a caeliferan grasshopper, Chorthippus biguttulus

Klappert K, Butlin RK, Reinhold K. The attractiveness fragment - AFLP analysis of local adaptation and sexual selection in a caeliferan grasshopper, Chorthippus biguttulus. NATURWISSENSCHAFTEN. 2007;94(8):667-674.Genetic variability among males is a necessary precondition for the evolution of female choice based on indirect genetic benefits. In addition to mutations and host-parasite cycles, migration of locally adapted individuals offers an explanation for the maintenance of genetic variability. In a previous study, conducting a reciprocal transplant experiment on a grasshopper, Chorthippus biguttulus, we found that environmental conditions significantly influenced not only body condition but also an important trait of male calling song, the amplitude of song. Although not significant, all other analysed physical and courtship song traits and attractiveness were superior in native than in transferred males. Thus, we concluded that local adaptation has a slight but consistent influence on a range of traits in our study populations, including male acoustic attractiveness. In our present study, we scanned male grasshoppers from the same two populations for amplification fragment length polymorphism (AFLP) loci connected with acoustic attractiveness to conspecific females. We found greater differences in allele frequencies between the two populations, for some loci, than are expected from a balance between drift and gene flow. These loci are potentially connected with locally adapted traits. We examined whether these alleles show the proposed genotype environment interaction by having different associations with attractiveness in the two populations. One locus was significantly related to sexual attractiveness; however, this was independent of the males' population affiliation. Future research on the evolution of female choice will benefit from knowledge of the underlying genetic architecture of male traits under intraspecific sexual selection, and the 'population genomics' approach can be a powerful tool for revealing this structure

Host immune defence, dispersal and local parasite adaptation

Kurtz J, Klappert K, Schneider W, Reinhold K. Host immune defence, dispersal and local parasite adaptation. Evolutionary Ecology Research. 2002;4:431-439

Male courtship song and female preference variation between phylogeographically distinct populations of <em>Drosophila montana.</em>

Understanding the variation within and between populations in important male mating traits and female preferences is crucial to theories concerning the origin of sexual isolation by coevolution or other processes. There have been surprisingly few studies on the extent of variation and covariation within and between populations, especially where the evolutionary relationships between populations are understood. Here we examine variation in female preferences and a sexually selected male song trait, the carrier frequency of the song, within and between populations from different phylogeographic clusters of Drosophila montana. Song is obligatory for successful mating in this species, and both playback and field studies implicate song carrier frequency as the most important parameter in male song. Carrier frequency varied among three recently collected populations from Oulanka (Finland), Vancouver (Canada), and Colorado (central United States), which represent the main phylogeographic groups in D. montana. Males from Colorado had the most distinct song frequency, which did not follow patterns of genetic differentiation. There was considerable variation in preference functions within, and some variation between, populations. Surprisingly, females from three lines from Colorado seem to have preferences disfavoring the extreme male trait found in this population. We discuss sources of selection on male song and female preference.</p