PubMed · 15931199
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William J Sutherland. 2005-06-02. The best solution.. https://doi.org/10.1038/435569a
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Local adaptation represents a pivotal theme in evolutionary biology. The Opisthopappus genus, comprising Opisthopappus longilobus and O. taihangensis, thrives on the cliffs of the Taihang Mountains. During their evolutionary history, two species are hypothesized to have locally adapted to their cliff habitats. In the present study, we employed a combined approach of whole-genome sequencing of O. taihangensis and population genomic analysis from both species to gain deeper insights into their patterns of local adaptation. Our results revealed that the expansive genome of O. taihangensis (3010.18 Mb), a consequence of a whole-genome duplication (WGD) event, coupled with a high proportion of repetitive sequences (82.70%), was postulated as one of its adaptive strategies. A clear differentiation between O. taihangensis and O. longilobus was observed, with the two species diverging approximately 17.57 million years ago (Mya), with O. longilobus serving as the ancestor. Since their divergence, limited gene flow was observed between the two species. Post-divergence, the effective population sizes of both species expanded, yet underwent a dramatic reduction at approximately 0.07 Mya. Furthermore, a total of 798 adaptive genes were identified, of which 207 overlapped with expanded genes, and eight genes were found to be under positive selection. These genes primarily regulated the growth and development of both species via pathways such as oxidation-reduction and ubiquitin-proteasome, enabling them to withstand climate changes. These findings provide profound insights into the local adaptation of Opisthopappus species to the cliff environments and offer valuable clues for further exploring the local adaptation among various cliff-dwelling organisms.
In this report, we examine the hypothesis that the drivers of latitudinal selection observed in the eastern US Drosophila melanogaster populations are reiterated within seasons in a temperate orchard population in Pennsylvania, USA. Specifically, we ask whether alleles that are apparently favoured in northern populations are also favoured early in the spring, and decrease in frequency from the spring to autumn with the population expansion. We use SNP data collected for 46 metabolic genes and 128 SNPs representing the central metabolic pathway and examine for the aggregate SNP allele frequencies whether the association of allele change with latitude and that with increasing days of spring-autumn season are reversed. Testing by random permutation, we observe a highly significant negative correlation between these associations that is consistent with this expectation. This correlation is stronger when we confine our analysis to only those alleles that show significant latitudinal changes. This pattern is not caused by association with chromosomal inversions. When data are resampled using SNPs for amino acid change the relationship is not significant but is supported when SNPs associated with cis-expression are only considered. Our results suggest that climate factors driving latitudinal molecular variation in a metabolic pathway are related to those operating on a seasonal level within populations.
In a series of environmentally realistic laboratory experiments, toxicokinetics and effects of polychlorinated biphenyls (PCBs) were studied in the Arctic charr (Salvelinus alpinus). Winter fasting and emaciation, which are common among Arctic charr living in high latitudes, resulted in a redistribution of the lipophilic PCBs from lipid-storing tissue such as the muscle, to vital organs that must be considered sensitive toward PCB (liver and brain). This redistribution was accompanied by a significant potentiation of the hepatic cytochrome P-450 (CYP) 1A biomarker response, from low activities in October (within those measured in uncontaminated charr) to a high, probably maximum, induction in May. Performance studies demonstrated a clear effect of environmentally realistic PCB levels on endocrine mechanisms, immune function, and seawater preadaptation (smoltification) in charr that had been feed deprived for several months after contamination with Aroclor 1254, whereas a high PCB dose exerted only minor, if any, effects in charr that had been fed after contamination. These results demonstrate that emaciation results in decreased dose-response relationships in fish, and indicate that arctic animals undergoing seasonal cycles of "fattening" and emaciation may be extra sensitive toward persistent, lipophilic organochlorines. Pilot studies on Arctic charr from Bjørnøya Island revealed marked CYP1A biomarker responses and an upregulation of genes involved in cellular homeostatic mechanisms in charr from Lake Ellasjøen (high PCB levels).