Friesea grisea is the only springtail species currently described from both East (Victoria Land) and West Antarctica (Antarctic Peninsula), although levels of genetic divergence between the two regions suggest the possibility of cryptic species. Determining the genetic structure of populations in the two regions is necessary in order to compare the effects of the different environmental conditions in the two regions, the different evolutionary histories of their inhabitants, and for assessing any influence of latitude in each region on genetic diversity. We analysed sequences of the mitochondrial COX1 and ATP6 genes from a total of 111 individuals for 17 sites (nine on the Antarctic Peninsula and eight in Victoria Land), to assess levels of genetic diversity. Both regions have their own unique sets of haplotypes, differing by about 20% of their nucleotide sequences. A similar number of haplotypes was found in the two regions, and within each we found two groups of populations sharing no haplotypes. In the Antarctic Peninsula, two, presumably ancestral, haplotypes are dominant in frequency. In Victoria Land, the Cape Hallett population showed a distinct set of haplotypes, genetically different from the southernmost populations, suggesting differentiation on pre-Pleistocene timescales.

Human herpesviruses 6-A and -B (HHV-6A, HHV-6B) are ubiquitous in human populations worldwide. These viruses have been associated with several diseases such as multiple sclerosis, Hodgkin’s lymphoma or encephalitis. Despite of the need to understand the genetic diversity and geographic stratification of these viruses, the availability of complete viral sequences from different populations is still limited. Here, we present nine new inherited chromosomally integrated HHV-6 sequences from diverse geographical origin which were generated through target DNA enrichment on lymphoblastoid cell lines derived from healthy individuals. Integration with available HHV-6 sequences allowed the assessment of HHV-6A and -6B phylogeny, patterns of recombination and signatures of natural selection. Analysis of the intra-species variability showed differences between A and B diversity levels and revealed that the HHV-6B reference (Z29) is an uncommon sequence, suggesting the need for an alternative reference sequence. Signs of geographical variation are present and more defined in HHV-6A, while they appear partly masked by recombination in HHV-6B. Finally, we conducted a scan for signatures of selection in protein coding genes that yielded at least 6 genes (4 and 2 respectively for the A and B species) showing significant evidence for accelerated evolution, and 1 gene showing evidence of positive selection in HHV-6A.

High condition enables individuals to express a phenotype with greater reproductive potential. However, life-history theory predicts that reproduction will trade off with somatic maintenance and viability, and several studies have reported faster age-related decline in performance in high-condition individuals, suggesting that high condition in early life is associated with accelerated somatic deterioration. This trade-off may be especially pronounced in males, which often express condition-dependent secondary sexual traits that can impose viability costs during development and through damage-inflicting adult sexual behaviours. To test this prediction, we reared larvae of the neriid fly Telostylinus angusticollis on diets of varying nutrient content and quantified somatic deterioration in solitary males, males housed in all-male or mixed-sex groups and immobilized males subjected to mechanical stress. We found that males reared on a nutrient-rich larval diet (high-condition males) suffered a higher rate of somatic deterioration with age, particularly when housed in groups. Perhaps as a result of accelerated somatic deterioration, high-condition males did not outlive low-condition males. In addition, high-condition males housed in all-male groups experienced a greater reduction in escape response with age than males housed in mixed-sex groups, suggesting that male-male combat promotes somatic deterioration. However, even when immobilized, high-condition males were still found to be more susceptible to somatic damage than low-condition males. Our findings suggest that a high-condition male phenotype is more prone to somatic damage, both as a result of associated behaviours such as combat, and because of the inherent fragility of the high-condition body.