Genetic divergence among threespine stickleback that differ in nuptial coloration.

Sexual signals are shaped by their intended and unintended receivers as well as the signalling environment. This interplay between sexual and natural selection can lead to divergence in signals in heterogeneous environments. Yet, the extent to which gene flow is restricted when signalling phenotypes vary across environments and over what spatial scales remains an outstanding question. In this study, we quantify gene flow between two colour morphs, red and black, of freshwater threespine stickleback fish (Gasterosteus aculeatus). We capitalize on the very recent divergence of signalling phenotypes in this system to characterize within-species and among-morph genetic variation and to test for levels of gene flow between colour morphs in Oregon and Washington. Despite limited evidence for assortative mating between allopatric red and black populations, we found that black populations are genetically distinct from nearby red populations and that the black morph appears to have evolved independently at least twice in Oregon and Washington. Surprisingly, we uncovered a group of stickleback in one small coastal stream, Connor Creek, which is genetically and morphologically distinct from the red and black colour morphs and from marine stickleback. Historically, both colour morphs have coexisted in this location and sometimes hybridized, raising new questions about the origins and history of these fish, which were first described as anadromous-black hybrids >50 years ago. Understanding how genetic variation is currently partitioned within and among populations and colour morphs in this system should prompt future studies to assess the relative roles of habitat, ecological and pre- and post-reproductive barriers in the genetic divergence and phenotypic patterns we observe in nature.

No genomic repercussions of assortative pairing in a colour polymorphic lizard.

Long-term maintenance of colour polymorphisms often depends on the interplay of multiple selective forces. In the common wall lizard (Podarcis muralis), up to three pure and two mosaic ventral colour morphs co-exist across most of its range. Available evidence suggests that colour morphs in this species are maintained through the interaction between sexual and environment-dependent selection. In particular, colour-assortative pairing has been recorded, suggesting some degree of assortative mating. Here, we combined reduced-representation sequencing (ddRADseq) and fine-scale distribution data to explore the effects of assortative pairing on the common wall lizard. Overall, our results do not support any population structure (FST  = 0 and K = 1) nor a significant effect of colour morph or geographic location on genomic differentiation. Therefore, we argue that assortative pairing may not fully translate into assortative mating and genomic differentiation between colour morphs and discuss possible explanations. Nonetheless, we find potential support for an elevated population size and/or source-sink dynamics and debate the potential contribution of other forms of selection to the maintenance of colour polymorphisms in lacertids.

Review of the genus Calotelea Westwood, 1837 (Platygastroidea: Scelionidae) of India.

The genus Calotelea Westwood, 1837 (Scelionidae) of the Indian region is revised. Fifteen new species of Calotelea - C. andamanensis sp. n., C. aurea sp. n., C. brevinotaularis sp. n., C. hodgsoni sp. n., C. kannagiae sp. n., C. lambodara sp. n., C. longistriata sp. n., C. mandavyai sp. n., C. marykingsleyae sp. n., C. microtrichiana sp. n., C. nigriventris sp. n., C. oloftoreni sp. n., C. sibyllamerianae sp. n., C. sushrutai sp. n. and C. trikona sp. n. - are described and imaged. Images of previously described species, C. auriventria Sharma, 1978 and C. immaculata Sharma, 1982, are also provided. Calotelea cameroni (Masner, 1965) is revalidated and redescribed as Probaryconus cameroni Masner, 1965 status revalidated based on morphological characters. Keys to females and known males of Indian species of Calotelea are furnished. While sexual dimorphism with differently coloured males and females has been reported earlier in some species of Calotelea, intrasexual colour dimorphism among females of a species is reported here for the first time.

A non-coding region near Follistatin controls head colour polymorphism in the Gouldian finch.

Discrete colour morphs coexisting within a single population are common in nature. In a broad range of organisms, sympatric colour morphs often display major differences in other traits, including morphology, physiology or behaviour. Despite the repeated occurrence of this phenomenon, our understanding of the genetics that underlie multi-trait differences and the factors that promote the long-term maintenance of phenotypic variability within a freely interbreeding population are incomplete. Here, we investigated the genetic basis of red and black head colour in the Gouldian finch (Erythrura gouldiae), a classic polymorphic system in which naturally occurring colour morphs also display differences in aggressivity and reproductive success. We show that the candidate locus is a small (approx. 70 kb) non-coding region mapping to the Z chromosome near the Follistatin (FST) gene. Unlike recent findings in other systems where phenotypic morphs are explained by large inversions containing hundreds of genes (so-called supergenes), we did not identify any structural rearrangements between the two haplotypes using linked-read sequencing technology. Nucleotide divergence between the red and black alleles was high when compared to the remainder of the Z chromosome, consistent with their maintenance as balanced polymorphisms over several million years. Our results illustrate how pleiotropic phenotypes can arise from simple genetic variation, probably regulatory in nature.

One gene, multiple alleles: insights into the microevolution of pigmentation polymorphisms.

Understanding how phenotypic variation is generated and maintained, and the evolutionary forces that shape these processes is the main goal of evolutionary biology. Great progress has been made in uncovering the genetic basis of morphological diversity, yet little is known about both the genetics and developmental basis of discrete polymorphisms segregating in wild populations. Exploring variation in developmental mechanisms at the population level can address the long-standing question of whether the mechanisms of change are the same at the micro- and macroevolutionary scale. This integration has been difficult mainly because the study of the evolution of developmental mechanisms and population genetics remain separate (Genetics, 195, 625 and 2013). In this issue of Molecular Ecology, Roberts et al. (Molecular Ecology and 2017) make a significant contribution towards bridging this gap by studying the genetic and developmental basis of an extremely variable pigmentation pattern. A polymorphic blotched coloration is common among females of four genera of Lake Malawi cichlids. The presence of this phenotype associates with a noncoding SNP upstream of the transcription factor pax7a (Science, 326, 998 and 2009). The authors describe in detail the morphs' pigmentation development, showing that phenotypic differences result from alterations in pigment cell development and survival. Next, using controlled crosses and population genetics studies, they identified three putative pax7a dominant blotch alleles that are associated with specific morphs. These different alleles lead to higher levels of pax7a transcript that correlate with different pigment cell composition. Finally, sequence comparison of the locus within populations and between species revealed a common origin of the allele controlling the blotched morph followed by a pattern of sequential appearance of derived alleles that gave rise to morph diversity. The coupling of the evolutionary history of this allelic series with the developmental analysis of the phenotype paves the way for a mechanistic understanding of morphological innovation and diversification.

An allelic series at pax7a is associated with colour polymorphism diversity in Lake Malawi cichlid fish.

Despite long-standing interest in the evolution and maintenance of discrete phenotypic polymorphisms, the molecular genetic basis of such polymorphism in the wild is largely unknown. Female sex-associated blotched colour polymorphisms found in cichlids of Lake Malawi, East Africa, represent a highly successful polymorphic phenotype, found and maintained in four genera across the geographic expanse of the lake. Previously, we identified an association with an allelic variant of the paired-box transcription factor gene pax7a and blotched colour morphs in Lake Malawi cichlid fishes. Although a diverse range of blotched phenotypes are present in Lake Malawi cichlid species, they all appeared to result from an allele of pax7a that produces increased levels of transcript. Here, we examine the developmental and genetic basis of variation among blotched morphs. First, we confirm that pax7a-associated blotch morphs result primarily from modulation of melanophore development and survival. From laboratory crosses and natural population studies, we identify at least three alleles of pax7a associated with discrete subtypes of blotched morphs, in addition to the ancestral pax7a allele. Genotypes at pax7a support initial evolution of a novel pax7a allele to produce the blotched class of morphs, followed by subsequent evolution of that pax7a blotched allele to produce additional alleles associated with discrete colour morphs. Variant alleles of pax7a produce different levels of pax7a transcript, correlating with pigmentation phenotype at the cellular level. This naturally selected allelic series should serve as a case study for understanding the molecular genetic control of pax7a expression and the evolution of sex-associated alleles.

Description of a new species of the Petrolisthesgalathinus complex from the Caribbean Sea, and resurrection of Petrolisthesoccidentalis from the East Pacific (Crustacea, Anomura, Porcellanidae).

The Petrolisthesgalathinus complex currently consists of six American species distributed in the West Atlantic, including the amphi-American P.galathinus. All species in the complex are similar in their adult morphology but differ in colour, size, larval morphology, and shape of the adult sternal plate. The West Atlantic species have different geographic ranges, which overlap in the southern Caribbean. Previously published molecular data support the monophyly of the complex, and the reciprocal monophyly of each described species and further clades corresponding to different colour morphs. Here, the morph P.caribensis "Blue" is described as Petrolisthescoeruleussp. nov., and Petrolisthesoccidentalis is formally resurrected for the Pacific individuals of P.galathinus. By adding these two species to the P.galathinus complex, this now consists of eight species. Colour illustrations of all species and colour morphs are provided and their geographic distributions and ecological ranges are discussed and updated.

Molecular tracking and prevalence of the red colour morph restricted to a harvested leopard population in South Africa.

The red leopard (Panthera pardus) colour morph is a colour variant that occurs only in South Africa, where it is confined to the Central Bushveld bioregion. Red leopards have been spreading over the past 40 years, which raises the speculation that the prevalence of this phenotype is related to low dispersal of young individuals owing to high off-take in the region. Intensive selective hunting tends to remove large resident male leopards from the breeding population, which gives young male leopards the chance to mate with resident female leopards that are more likely to be their relatives, eventually increasing the frequency of rare genetic variants. To investigate the genetic mechanisms underlying the red coat colour morph in leopards, and whether its prevalence in South Africa relates to an increase in genetic relatedness in the population, we sequenced exons of six coat colour-associated genes and 20 microsatellite loci in twenty Wild-type and four red leopards. The results were combined with demographic data available from our study sites. We found that red leopards own a haplotype in homozygosity identified by two SNPs and a 1 bp deletion that causes a frameshift in the tyrosinase-related protein 1 (TYRP1), a gene known to be involved in the biosynthesis of melanin. Microsatellite analyses indicate clear signs of a population bottleneck and a relatedness of 0.11 among all pairwise relationships, eventually supporting our hypothesis that a rare colour morph in the wild has increased its local frequency due to low natal dispersal, while subject to high human-induced mortality rate.

The invasion history, distribution and colour pattern forms of the harlequin ladybird beetle Harmonia axyridis (Pall.) (Coleoptera, Coccinellidae) in Slovakia, Central Europe.

The harlequin ladybird beetle Harmonia axyridis (Coleoptera, Coccinellidae) has invaded and established in Slovakia. Following unintentional introduction in 2008, the spread of the alien coccinellid was very fast. By the end of 2009, it was recorded across the whole country, and by the end of 2012 it was widely distributed and common in various habitats, particularly gardens, orchards and urban areas, where it was most frequent on trees. The rate of eastward spread was approximately 200 km year(-1), similar to the overall rate of spread in Europe. Between 2008 and 2012, the coccinellid was recorded in a total of 153 localities, in altitudes ranging from 98 to 1,250 m. Most records of this species were made in lowlands, hilly areas and valleys separating mountain ridges. However, it was only rarely documented in areas above 700 m a.s.l. The non-melanic colour form (f. succinea) was dominant along a longitudinal transect including eight urban areas across Slovakia, with the frequency of melanic forms (f. spectabilis and f. conspicua together) between 6.3 and 19.2% and a median equal to 10.5%. The invasion history and distribution of H. axyridis in Slovakia are discussed with regard to the time sequence of records, rate of spread, altitudinal distribution, anthropogenic dispersal, effective recording, proportion of melanic forms and other relevant aspects associated with the spread of this successful invader.