Heredity最新文献

Genetics and eugenics co-evolved at the beginning of the twentieth century and remained associated through the 1940s and beyond. Early geneticists were far from unanimous in their views on eugenics; some avidly supported the movement, whereas others openly opposed it or chose to remain detached. Academic institutions and scientific societies are currently reckoning with their past associations with eugenics. This article highlights historical connections between the UK Genetics Society and the eugenics movement in Britain. The complexity of these connections is illustrated through case studies of three notable Genetics Society past Presidents-J. B. S. Haldane, R. A. Fisher, and L. S. Penrose-who represent diverse ways that British geneticists engaged with the eugenics movement, from career-long support to science-based opposition. Their contributions to, and critiques of, eugenics are situated in their scientific and historical contexts. We reflect on the historical role of professional genetics organisations in facilitating the rise of eugenics in the early twentieth century, and the present responsibility of the same organisations to combat its contemporary revival.

The importance of populations inhabiting ecologically marginal areas has been extensively debated and shown to depend largely on their adaptive value. These populations may harbour unique genetic combinations essential for long-term resilience. This study investigates the adaptive value of marginal populations through a multidimensional genomic analysis that integrates selective signals, neutral processes, and temporal scales. Using targeted exome sequencing, we searched for genomic signatures of divergent selection between environmentally marginal and core populations of the Mediterranean alpine species Silene ciliata. We also analysed genetic population structure, demographic history, and selective sweeps at different levels. Populations from core and marginal environments showed similar values of nucleotide diversity, inbreeding, and relatedness. Demographic reconstructions revealed that marginal, low-elevation populations functioned as stable historical rear-edges (refugia) during post-glacial upslope colonization, retaining high effective population sizes despite current demographic decline. We detected putative signals of diversifying selection involving 11 SNPs in nine genes and five gene pathways (e.g., RNA transport and stress-response metabolism), suggesting that local adaptation persists despite high gene flow. Our findings demonstrate that current environmental suitability is a poor predictor of genetic diversity, which is instead primarily shaped by historical stability. These results underscore the critical value of marginal populations as evolutionary reservoirs that can provide the genetic variation necessary for adaptive responses to climate change through gene flow.

Organisms vary in their ability to cope with environmental perturbations, and even closely related species can differ in their resilience to climate change. For example, generalists may be better at accommodating environmental change than specialists with a narrow ecological niche. However, many species are difficult to classify as "specialist" or "generalist", and may be merely adapted to distinct ecological niches. Furthermore, climate resilience may vary between ecological specialists if consequences are more profound for one ecological niche than another. In this study, we employ a multi-locus exon-capture approach and combine phylogeographic and population genetic methods to compare the evolutionary history of four species of Australian Cryptoblepharus lizards. These skinks co-occur in the Australian Monsoonal Tropics (AMT), have persisted despite major changes in Pleistocene climate, and have adapted to arboreal or rock substrates (two arboreal, two rock specialists). We find that phylogeographic structure is idiosyncratic between species and ecomorphs, likely shaped by the complex topography and heterogeneous environment of the AMT. In contrast, demographic analyses recovered largely congruent signals of expansion across populations, suggesting shared responses to past environmental change independent of ecomorph type. These results show that ecological specialization per se is not always a good predictor of demographic history or phylogeographic structure, and highlight the complex interplay between topography and climate history in promoting diversification. Thus, while ecological specialization, niche breadth, and other species-specific characteristics remain of interest, major landscape features that serve as biogeographic barriers or refugia may mask idiosyncratic responses between ecomorphs from the same adaptive radiation.

Very little is known about the origins and history of domestic chickens (Gallus gallus domesticus) in northern Europe due to a lack of existing documentary and ancient DNA evidence from this region. Therefore, we conducted ancient DNA analyses and radiocarbon dating of archaeological chicken bones from the Baltic Sea region (Finland, Estonia, and Lithuania). We sequenced a 201-bp long fragment of the mitochondrial control region as well as SNPs (single nucleotide polymorphisms) from the thyroid-stimulating hormone receptor (TSHR) gene and the β-carotene dioxygenase 2 (BCDO2) gene, comparing with modern Finnish and Estonian landrace chickens, as well as with other ancient and modern chickens. All studied ancient chickens belonged to a prevalent E1 mitochondrial haplogroup, except one individual from the Åland Islands (haplogroup B). Allele frequencies differed between ancient Baltic and Finnish chickens from Åland Islands in TSHR and BCDO2 genes, with Åland harbouring more individuals with grey skin. Interestingly, yellow-skinned chickens were more common in mainland Finland and Baltic countries during ancient times than in central and southern Europe. Mitochondrial haplogroup A was present in modern Finnish landrace chickens but not in ancient samples from the early Finnish Iron Age to the early modern period (3^rd-18^th century CE), indicating later introgression. Both Estonian and Finnish landrace chickens had a higher frequency of the TSHR wild-type allele than the modern reference samples. Based on our results, the ancient chickens from the Åland Islands differed from other ancient chickens from the Baltic Sea region, and the landrace chickens differ from other modern chickens.

In populations of fish species, polygenic sex determination (PSD) can evolve in different directions, depending on environmental fluctuations and migration rates. The European seabass provides an interesting model to explore such evolutionary phenomena, because it exhibits a PSD, mainly driven by temperature and has three genetically differentiated populations evolving from a common PSD ancestor. We produced experimental offspring of the three populations (AT = Atlantic, WM = Western Mediterranean, and EM = Eastern Mediterranean) and reared them in four thermal regimes mimicking temperatures encountered in the Atlantic (rAT), Western Mediterranean (rWM), Eastern Mediterranean (rEM), plus a husbandry regime maximizing the proportion of females (rAQUA). For AT, we found a relatively balanced sex-ratio and a significantly higher proportion of females than WM and EM. The WM population had male-biased sex-ratios, especially in the colder regimes (rAT, rWM), with no differences from the EM population. The WM had sex-ratios intermediate between AT and EM in the warmer regimes (rEM, rAQUA). Genetic correlations for sex tendencies were high, and the heritability, around 0.62 ± 0.07, was consistent among populations and thermal regimes. Significant interactions of population x thermal regime were found for sexual size dimorphism (SSD), favoring females, where the SSD for AT fish increased with rising temperatures. GWAS showed seven significant SNPs located in LG19 for the AT population, with one QTL region containing one gene involved in fish sex determination. No QTLs were found for WM and EM. Overall, these findings reveal different adaptive evolution of the sex determination system across the populations.

Insects are associated with diverse RNA viruses, including vertically transmitted viruses that form persistent infections without apparent symptoms. One of the first documented vertically transmitted viruses is a sigmavirus (Rhabdoviridae) affecting fitness of Drosophila. Sigmaviruses and related rhabdoviruses have also been detected in pest fruit flies and other arthropods. However, their prevalence, transmission, tissue localisation and fitness effects remain poorly known, despite their potentially common infections in diverse hosts. We investigated Sigmavirus tryoni (BtSV) prevalence, load, transmission across multiple generations and host effects in Queensland fruit fly (Bactrocera tryoni), Australia's most significant horticultural pest, which carries BtSV at low prevalence (13.7%) across field populations. We detected BtSV in 6 of 12 laboratory populations (at a prevalence of 12.5% to 80.4%) where it was transmitted biparentally within embryos. Although incomplete, maternal transmission was more reliable and resulted in higher BtSV load than paternal transmission. Paternally transmitted BtSV was almost entirely lost after two generations. BtSV became detectable in most uninfected individuals cohabiting with infected flies, but this resulted in a low load that was subsequently transmitted to only few offspring. BtSV occurred across developmental stages, digestive and reproductive tissues, albeit its viral load was lower in reproductive tissues when received paternally than maternally, and lower in testes than ovaries. Furthermore, BtSV-infected individuals suffered paralysis and mortality when exposed to high CO₂ concentrations at low temperature, a Rhabdoviridae effect previously reported for Drosophila species, a muscid fly and mosquitoes. Our study suggests that sigmavirus transmission dynamics and fitness effects may apply broadly to arthropod hosts and affect their management.

Theoretical and empirical studies of reinforcement have advanced our understanding of speciation, yet its role in polymorphic species remains understudied. Because morphs differ in behavior, morphology, and reproductive strategies, reinforcement may act unevenly among them, generating asymmetric reproductive isolation. We tested this prediction in the polymorphic damselflies Ischnura elegans and Ischnura graellsii, in which female morphs adopt alternative reproductive strategies. These species form two independent hybrid zones where reinforcement has strengthened mechanical isolation and driven reproductive character displacement in mating-related structures. We quantified five reproductive barriers across female morphs to evaluate how color polymorphism interacts with reinforcement. We found clear asymmetry between morphs: gynochrome females of both species showed reinforced mechanical isolation, whereas androchromes did not, consistent with their contrasting reproductive strategies. Additionally, gametic barriers evolved in opposite directions between species. Fertility isolation was reinforced in I. elegans, while oviposition and fertility barriers relaxed in I. graellsii, but symmetrically between female morphs, likely reflecting gene flow and purging of incompatibilities. Reinforcement strengthened reproductive isolation in a morph-specific manner, as pre-existing differences between female morphs influenced the likelihood of heterospecific mating and therefore the strength of selection against hybridization. Future work should examine whether these asymmetric dynamics generate cascading effects within species and contribute to morph-level diversification.

Small populations face high extinction risks. This can be explained by several non-genetic and genetic factors, the latter including the loss of genetic diversity and evolutionary potential, as well as the accumulation of harmful mutations (genetic load). Using whole-genome data from island populations with different effective sizes, we estimated genetic variation and load and explored the relationship between these quantities. An extremely small population of the Aeolian wall lizard, Podarcis raffonei, likely isolated for tens of thousands of years, shows the lowest genome-wide heterozygosity observed in wild eukaryotes (one polymorphic site every 300 kb on average). Despite this, its realized genetic load is comparable to that observed in another larger and more genetically variable population. Both populations have lower variation and higher load than the much more abundant sister species, the Sicilian wall lizard. These observations are consistent with the hypothesis that populations experiencing severe bottlenecks may persist for extended periods with extremely low genomic variation, provided that their burden of deleterious mutations remains within tolerable bounds.