No abstract

Identification of the role of the MC1R gene has provided major insights into variation in skin pigmentation in several organisms, including humans, but the evolutionary genetics of this variation is less well-established. Variation in this gene and its relationship with degree of melanism was analyzed in one of the world’s highest-elevation lizards, Phrynocephalus theobaldi from the Qinghai-Tibetan Plateau. Individuals from the low-elevation group were shown to have darker dorsal pigmentation than individuals from a high-elevation group. The existence of climatic variation across these elevations was quantified, with lower elevations exhibiting higher air pressure, temperatures and humidity, but less wind and insolation. Analysis of the MC1R gene in 214 individuals revealed amino acid differences at five sites between intraspecific sister lineages from different elevations, with two sites showing distinct fixed residues at low elevations. Three of the four SNPs that underpinned these amino acid differences were highly-significant outliers, relative to the generalized MC1R population structuring, suggestive of selection. Transfection of cells with an MC1R allele from a lighter high-elevation population caused a 43% reduction in agonist-induced cAMP accumulation, and hence lowered melanin synthesis, relative to transfection with an allele from a darker low elevation population. The high-elevation allele led to less efficient integration of the MC1R protein into melanocyte membranes. Our study identifies variation in the degree of melanism that can be explained by four or fewer MC1R substitutions. We establish a functional link between these substitutions and melanin synthesis and demonstrate elevation-associated shifts in their frequencies.

No abstract

Nymphoides peltata is an aquatic floating weed widely distributed in the northern hemisphere of Eurasia. To better determine its phylogenetic relationships with other Nymphoides species and other aquatic plant species, the chloroplast genome of N. peltata was sequenced. The chloroplast genome size is 152,198 bp, consisting of a large single-copy region (84,223 bp) and a small single-copy region (17,817 bp) separated by a pair of inverted repeats with a length of 25,079 bp. The chloroplast genome contains 127 genes, including 85 protein-coding genes, 34 tRNA genes, and eight rRNAs. The maximum-likelihood phylogenetic tree showed that N. peltata is more closely related to other Nymphoides species, providing new insight into the evolution and genetic diversity of aquatic weeds.