| 1. |
|
|
| 2. |
- Qu, Yanhua, 1974-, et al.
(författare)
-
The evolution of ancestral and species-specific adaptations in snowfinches at the Qinghai-Tibet Plateau
- 2021
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 10.1073/pnas.2012398118:13, s. e2012398118-e2012398118
-
Tidskriftsartikel (refereegranskat)abstract
- Species in a shared environment tend to evolve similar adaptations under the influence of their phylogenetic context. Using snowfinches, a monophyletic group of passerine birds (Passeridae), we study the relative roles of ancestral and species-specific adaptations to an extreme high-elevation environment, the Qinghai–Tibet Plateau. Our ancestral trait reconstruction shows that the ancestral snowfinch occupied high elevations and had a larger body mass than most nonsnowfinches in Passeridae. Subsequently, this phenotypic adaptation diversified in the descendant species. By comparing high-quality genomes from representatives of the three phylogenetic lineages, we find that about 95% of genes under positive selection in the descendant species are different from those in the ancestor. Consistently, the biological functions enriched for these species differ from those of their ancestor to various degrees (semantic similarity values ranging from 0.27 to 0.5), suggesting that the three descendant species have evolved divergently from the initial adaptation in their common ancestor. Using a functional assay to a highly selective gene, DTL, we demonstrate that the nonsynonymous substitutions in the ancestor and descendant species have improved the repair capacity of ultraviolet-induced DNA damage. The repair kinetics of the DTL gene shows a twofold to fourfold variation across the ancestor and the descendants. Collectively, this study reveals an exceptional case of adaptive evolution to high-elevation environments, an evolutionary process with an initial adaptation in the common ancestor followed by adaptive diversification of the descendant species.
|
|
| 3. |
- Liu, Han, et al.
(författare)
-
A Chromosome-Level Assembly of Blunt Snout Bream (Megalobrama amblycephala) Genome Reveals an Expansion of Olfactory Receptor Genes in Freshwater Fish
- 2021
-
Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 38:10, s. 4238-4251
-
Tidskriftsartikel (refereegranskat)abstract
- The number of olfactory receptor genes (ORs), which are responsible for detecting diverse odor molecules varies extensively among mammals as a result of frequent gene gains and losses that contribute to olfactory specialization. However, how OR expansions/contractions in fish are influenced by habitat and feeding habit and which OR subfamilies are important in each ecological niche is unknown. Here, we report a major OR expansion in a freshwater herbivorous fish, Megalobrama amblycephala, using a highly contiguous, chromosome-level assembly. We evaluate the possible contribution of OR expansion to habitat and feeding specialization by comparing the OR repertoire in 28 phylogenetically and ecologically diverse teleosts. In total, we analyzed > 4,000 ORs including 3,253 intact, 122 truncated, and 913 pseudogenes. The number of intact ORs is highly variable ranging from 20 to 279. We estimate that the most recent common ancestor of Osteichthyes had 62 intact ORs, which declined in most lineages except the freshwater Otophysa clade that has a substantial expansion in subfamily beta and epsilon ORs. Across teleosts, we found a strong association between duplications of beta and epsilon ORs and freshwater habitat. Nearly, all ORs were expressed in the olfactory epithelium (OE) in three tested fish species. Specifically, all the expanded beta and epsilon ORs were highly expressed in OE of M. amblycephala. Together, we provide molecular and functional evidence for how OR repertoires in fish have undergone gain and loss with respect to ecological factors and highlight the role of beta and epsilon OR in freshwater adaptation.
|
|
