Whittall, J. | bioRxiv Science

bioRxiv2023

Can a flower color ancestral polymorphism transcend speciation?

Polymorphisms are common in nature, but they are rarely shared among closely related species. They could originate through convergence, ancestral polymorphism, or introgression. Although shared neutral genomic variation is commonplace, very few examples of shared functional traits exist. The blue-orange petal color polymorphisms in two closely related species, Lysimachia monelli and L. arvensis were investigated with UV-vis reflectance spectra, flavonoid biochemistry, and transcriptome comparisons followed by climate niche analysis. The similarities in reflectance spectra, biochemistry, and transcriptomes suggest a single shift from blue-to-orange shared by both lineages is possible. Transcriptome comparisons reveal two orange-specific genes are directly involved in both blue-orange color polymorphisms: DFR-2 specificity redirects flux from the malvidin to the pelargonidin while BZ1-2 stabilizes the pelargonidin with glucose, producing the orange pelargonidin 3-glucoside. The climate niches for each color morph are the same between the two species for three temperature characteristics but differ for four precipitation variables. We suggest that this persistent flower color polymorphism may represent an ancestrally polymorphic trait that has transcended speciation with some unique ecological effects.

evolutionary biology↗

bioRxiv2019

Unexpected predicted length variation for the coding sequence of the sleep related gene, BHLHE41 in gorilla amidst strong purifying selection across mammals

There is a molecular basis for many sleep patterns and disorders involving circadian clock genes. In humans, \"short-sleeper\" behavior has been linked to specific amino acid substitutions in BHLHE41 (DEC2), yet little is known about variation at these sites and across this gene in mammals. We compare BHLHE41 coding sequences for 27 mammals. The coding sequence alignment length was 1794bp, of which 55.0% of base pairs were invariant among the sampled mammals. The mean pairwise nucleotide identity was 92.2%. Of the 598 residue amino acid alignment for mammals, 71.7% of amino acids were identical. The pairwise percent identity for amino acids was 94.8%. No other mammals had the same \"short-sleeper\" amino acid substitutions previously described from humans. Phylogenetic analyses based on the nucleotides of the coding sequence alignment are consistent with established mammalian relationships. Significant purifying selection was detected in 66.2% of variable codons. No codons exhibited significant signs of positive selection. Unexpectedly, the gorilla BHLHE41 sequence has a 318 bp insertion at the 5 end of the coding sequence and a deletion of 195 bp near the 3 end of the coding sequence (including the two short sleeper variable sites). Given the strong signal of purifying selection across this gene, phylogenetic congruence with expected relationships and generally conserved function among mammals investigated thus far, we suggest the unexpected indels predicted in the gorilla BHLHE41 may represent an annotation error and warrant experimental validation.

bioinformatics↗