A new subspecies of Сryptocephalus ergenensis Morawitz, 1863 (Coleoptera, Chrysomelidae) from Kazakhstan and significance of colour pattern polymorphism examination

Cryptocephalus apicalis species group is introduced and defined within the subgenus Asionus Lopatin, 1988. Cryptocephalus ergenensis Morawitz, 1863 from this group is first recorded in Eastern Kazakhstan and this form with unusual colour pattern is described herein as a new subspecies kalbensis Mikhailov, ssp. nov. The members of Cryptocephalus apicalis species group are keyed and illustrated. Significance of the colour pattern polymorphism in taxonomy is discussed.

Dissecting supergene: evidence for recombination suppression among multiple functional loci within inversions.

Supergenes are genetic architectures associated with discrete and concerted variation in multiple traits. It has long been suggested that supergenes control these complex polymorphisms by suppressing recombination between set of coadapted genes. However, because recombination suppression hinders the dissociation of the individual effects of genes within supergenes, there is still little evidence that supergenes evolve by tightening linkage between coadapted genes. Here, combining an landmark-free phenotyping algorithm with multivariate genome wide association studies, we dissected the genetic basis of wing pattern variation in the butterfly Heliconius numata. We showed that the supergene controlling the striking wing-pattern polymorphism displayed by this species contains many independent loci associated with different features of wing patterns. The three chromosomal inversions of this supergene suppress recombination between these loci, supporting the hypothesis that they may have evolved because they captured beneficial combinations of alleles. Some of these loci are associated with colour variations only in morphs controlled by inversions, indicating that they were recruited after the formation of these inversions. Our study shows that supergenes and clusters of adaptive loci in general may form via the evolution of chromosomal rearrangements suppressing recombination between co-adapted loci but also via the subsequent recruitment of linked adaptive mutations.

Genetic diversity in several genotypes of Algerian lentil using biochemical markers

Hammadi H, Hammouda-Bousbia D, Chaib G, Tir A. 2021. Genetic diversity in several genotypes of Algerian lentil using biochemical markers. Biodiversitas 22: 3494-2500. Studying seed storage proteins in legumes (Fabaceae) is very important besides its economic value; seed storage proteins play an important role in plant taxonomy because of the stability of their contents. The grain protein content and protein profiles of 12 lentil genotypes (Lens culinaris Medik.) were characterized based on protein profiling through SDS-PAGE. The obtained gel has shown forty bands ranged from 13 to 21 with molecular weight 10 to 120 KDa. Of which six monomorphic bands, thirty-four polymorphic bands and five unique bands in Flip90-31, Idlep3, idlep2, Idlep4 and Radjas genotypes. The protein banding pattern polymorphism (84%) revealed an inter-genotypic variability. The Idlep3 genotype is characterized by specific bands (or a specific marker), followed by the Flip90-31 genotype. So these two genotypes can be considered as valuable gene resources for further breeding programs.

Simple inheritance of color and pattern polymorphism in the steppe grasshopper Chorthippus dorsatus

The green–brown polymorphism of grasshoppers and bush-crickets represents one of the most penetrant polymorphisms in any group of organisms. This poses the question of why the polymorphism is shared across species and how it is maintained. There is mixed evidence for whether and in which species it is environmentally or genetically determined in Orthoptera. We report breeding experiments with the steppe grasshopper Chorthippus dorsatus, a polymorphic species for the presence and distribution of green body parts. Morph ratios did not differ between sexes, and we find no evidence that the rearing environment (crowding and habitat complexity) affected the polymorphism. However, we find strong evidence for genetic determination for the presence/absence of green and its distribution. Results are most parsimoniously explained by three autosomal loci with two alleles each and simple dominance effects: one locus influencing the ability to show green color, with a dominant allele for green; a locus with a recessive allele suppressing green on the dorsal side; and a locus with a recessive allele suppressing green on the lateral side. Our results contribute to the emerging contrast between the simple genetic inheritance of green–brown polymorphisms in the subfamily Gomphocerinae and environmental determination in other subfamilies of grasshoppers. In three out of four species of Gomphocerinae studied so far, the results suggest one or a few loci with a dominance of alleles allowing the occurrence of green. This supports the idea that brown individuals differ from green individuals by homozygosity for loss-of-function alleles preventing green pigment production or deposition.

A large and diverse autosomal haplotype is associated with sex-linked colour polymorphism in the guppy

Colour polymorphism provides a tractable trait that can be harnessed to explore the evolution of sexual selection and sexual conflict. Male colour patterns of the Trinidadian guppy (Poecilia reticulata) are governed by both natural and sexual selection, and are typified by extreme pattern colour variation as a result of negative frequency dependent selection. Since guppy colour patterns are often inherited faithfully from fathers to sons, it has been historically presumed that colour genes are physically linked to sex determining loci as a supergene on the sex chromosome. Yet the actual identity and genomic location of the colour pattern genes has remained elusive. We phenotyped and genotyped four guppy Iso-Y lines, where colour was inherited along the patriline, but backcrossed into the stock population every 2 to 3 generations for 40 generations, thereby homogenising the genome at regions unrelated to colour. Using an unbiased phenotyping method to proportion colour pattern differences between and among the Iso-Y lines, we confirmed that the breeding design was successful in producing four distinct colour patterns. Our analysis of genome resequencing data of the four Iso-Y lines uncovered a surprising genetic architecture for colour pattern polymorphism. Genetic differentiation among Iso-Y lines was repeatedly associated with a large and diverse haplotype (~5Mb) on an autosome (LG1), not the sex chromosome (LG12). Moreover, the LG1 haplotype showed elevated linkage disequilibrium and exhibited evidence of sex-specific diversity when we examined whole-genome sequencing data of the natural source population. We hypothesise that colour pattern polymorphism is driven by Y-autosome epistasis, and conclude that predictions of sexual conflict should focus on incorporating the effects of epistasis in understanding complex adaptive architectures.

Quantitative analysis of carapace pattern polymorphism in the grapsid crab Hemigrapsus penicillatus (De Haan, 1835) (Decapoda, Varunidae)

Many shore crabs exhibit juvenile colour pattern polymorphism on their carapace, which helps avoid predation through camouflage. However, colour pattern polymorphism has been described only in a limited number of species, and its quantitative descriptions are rare. Here, we studied the Asian grapsid crab Hemigrapsus penicillatus to describe its polymorphic dichromatic carapace patterns. We specifically examined how dichromatic patterns and the degree of pattern polymorphism change as size increases and whether sexual/size differences exist in carapace patterns. Our results showed that H. penicillatus exhibits polymorphic forms in both the juvenile and adult stages. Additionally, compared with males, females were more likely to exhibit dichromatic carapace patterns and had a larger light-coloured area on their carapace. Estimation of the likelihood of the carapace being light or dark coloured suggested that certain areas on the carapace are less variable than other areas. We discuss potential adaptive explanations for our results.

Mutation accumulation in chromosomal inversions maintains wing pattern polymorphism in a butterfly

While natural selection favours the fittest genotype, polymorphisms are maintained over evolutionary timescales in numerous species. Why these long-lived polymorphisms are often associated with chromosomal rearrangements remains obscure. Combining genome assemblies, population genomic analyses, and fitness assays, we studied the factors maintaining multiple mimetic morphs in the butterfly Heliconius numata. We show that the polymorphism is maintained because three chromosomal inversions controlling wing patterns express a recessive mutational load, which prevents their fixation despite their ecological advantage. Since inversions suppress recombination and hamper genetic purging, their formation fostered the capture and accumulation of deleterious variants. This suggests that many complex polymorphisms, instead of representing adaptations to the existence of alternative ecological optima, could be maintained primarily because chromosomal rearrangements are prone to carrying recessive harmful mutations.

Conservation and flexibility in the gene regulatory landscape of Heliconiine butterfly wings

BackgroundMany traits evolve by cis-regulatory modification, by which changes to non-coding sequences affect the binding affinity for available transcription factors and thus modify the expression profile of genes. Multiple examples of cis-regulatory evolution have been described at pattern switch genes responsible for butterfly wing pattern polymorphism, including in the diverse neotropical genus Heliconius, but the identities of the factors that can regulate these switch genes have not been identified.ResultsWe investigated the spatial transcriptomic landscape across the wings of three closely related butterfly species, two of which have a convergently-evolved, co-mimetic pattern, the other having a divergent pattern. We identified candidate factors for regulating the expression of wing patterning genes, including transcription factors with a conserved expression profile in all three species, and others, including both transcription factors and Wnt pathway genes, with markedly different profiles in each of the three species. We verified the conserved expression profile of the transcription factor homothorax by immunofluorescence, and showed that its expression profile strongly correlates with that of the selector gene optix in butterflies with the Amazonian forewing pattern element ‘dennis’.ConclusionsHere we show that, in addition to factors with conserved expression profiles like homothorax, there are also a variety of transcription factors and signaling pathway components that appear to vary in their expression profiles between closely related butterfly species, highlighting the importance of genome-wide regulatory evolution between species.