Nymphal colour/pattern polymorphism in the leafhoppers Eupteryx urticae (F.) and E. cyclops Matsumura (Hemiptera: Auchenorrhyncha): spatial and temporal variation in morph frequencies

Variation in colour/pattern morph frequencies in Eupteryx urticae and E. cyclops is described for various field populations. Eupteryx urticae populations in S Wales exhibit a steep morph-ratio cline, such that black morph frequencies are positively correlated with altitude. High melanic frequencies at high-altitude sites, and the absence of the two darker morphs in lowland populations, suggest a similar trend in E. cyclops , but the data are insufficient to confirm this statistically. No differences in morph frequencies were detected on different parts of the primary host plant or on alternative host species. Similarly, there were no consistent trends within or between the two annual generations of either species, although melanic morph frequencies in one E. urticae population were heterogeneous over 10 generations. It is suggested that the polymorphism in E. urticae is strongly influenced by climate selection, darker morphs being at an advantage in cooler environments where their coloration enhances absorption of solar radiation. The advantage gained through thermal melanism is probably balanced by visual selection against black morphs by entomophagous parasitoids.     

The genetics of the mimetic butterfly Hypolimnas bolina (L.).

Hypolimnas bolina is a Nymphalid butterfly having a west to east distribution from Madagascar to Easter Island, and a north to south one from Japan to Australasia. It is highly migratory in some areas. In much of the western part of its range the female is both monomorphic and a mimic of Euploea. Further east it is frequently polymorphic with the majority of the forms being non-mimetic. The polymorphism is sex-limited to the female and controlled by two unlinked loci, one with two allelomorphs, E and e, determining the extent of the dark pigmentation, the other with three allelomorphs, P, Pn and p, determining the presence and distribution of orange-brown. Only butterflies of the genotypes EEpp and to a lesser extent Eepp are satisfactory Batesian mimics of their Euploea models. The details of the mimetic pattern are under multifactorial control, following those of their local model, as is much of the variation within the non-mimetic forms, particularly with regard to the distribution of white and blue scaling.     

Convergence and divergence in lizard colour polymorphisms

Colour polymorphic species are model systems for examining the evolutionary processes that generate and maintain discrete phenotypic variation in natural populations. Lizards have repeatedly evolved strikingly similar polymorphic sexual signals in distantly related lineages, providing an opportunity to examine convergence and divergence in colour polymorphism, correlated traits and associated evolutionary processes. Herein, we synthesise the extensive literature on lizard colour polymorphisms in both sexes, including recent advances in understanding of the underlying biochemical, cellular and genetic mechanisms, and correlated behavioural, physiological and life-history traits. Male throat, head or ventral colour morphs generally consist of red/orange, yellow and white/blue morphs, and sometimes mixed morphs with combinations of two colours. Despite these convergent phenotypes, there is marked divergence in correlated behavioural, physiological and life-history traits. We discuss the need for coherence in morph classification, particularly in relation to ‘mixed’ morphs. We highlight future research directions such as the genetic basis of convergent phenotypes and the role of environmental variation in the maintenance of polymorphism. Research in this very active field promises to continue to provide novel insights with broad significance to evolutionary biologists.     

Search for methylation-sensitive amplification polymorphisms associated with the mantled variant phenotype in oil palm (Elaeis guineensis Jacq).

The methylation-sensitive amplification polymorphism (MSAP) technique has been employed on somatic embryo-derived oil palms (Elaeis guineensis Jacq.) to identify methylation polymorphisms correlated with the "mantled" somaclonal variation. The variant phenotype displays an unstable feminization of male organs in both male and female flowers. Using MSAP, the methylation status of CCGG sites was compared in three normal versus three mantled regenerants sampled in clonal populations obtained through somatic embryogenesis from four genotypically distinct mother palms. Overall, 64 selective primer combinations were used and they have amplified 23 markers exhibiting a differential methylation pattern between the two phenotypes. Our results indicate that CCGG sites are poorly affected by the considerable decrease in global DNA methylation that has been previously associated with the mantled phenotype. Each of the 23 markers isolated in the present study could discriminate between the two phenotypes only when they were from the same genetic origin. This result hampers at the moment the direct use of MSAP markers for the early detection of variants, even though valuable information on putative target sequences will be obtained from a further characterization of these polymorphic markers.     

The Mendelian inheritance of rare flesh and shell colour variants in the black‐lipped pearl oyster (Pinctada margaritifera)

Pinctada margaritifera is French Polynesia's most economically important aquaculture species. This pearl oyster has the specific ability to produce cultured pearls with a very wide range of colours, depending on the colour phenotypes of donor oysters used. Its aquaculture is still based on natural spat collection from wild stocks. We investigated three rare colour variants of P. margaritifera – orange flesh, and red and white shell colour phenotypes – in comparison with the wild‐type black flesh and shell commonly found in this species. The study aimed to assess the geographic distribution and genetic basis of these colour variants. Colour frequencies were evaluated during transfer and graft processes of pearl oyster seed captured at collector stations. Among the collection locations studied, Mangareva Island showed the highest rate of the orange flesh phenotype, whereas Takaroa and Takume atolls had relatively high rates of red and white shell phenotypes respectively. Broodstocks were made of these rare colour variants, and crosses were performed to produce first‐ and second‐generation progenies to investigate segregation. The results were consistent with Mendelian ratios and suggest a distinct model with no co‐dominance: (i) a two‐allele model for flesh trait, whereby the orange allele is recessive to the black fleshed type, and (ii) a three‐allele model for shell trait, whereby the black wild‐type allele is dominant to the red coloration, which is dominant to the white shell. Furthermore, the proposed model provides the basis for producing selected donor pearl oyster lines through hatchery propagation.     

Molecular phylogeny of mangroves. VI. Intraspecific genetic variation in mangrove species Excoecaria agallocha L. (Euphorbiaceae).

Genomic DNA from 84 individuals of Excoecaria agallocha from seven mangrove populations were analysed for random amplified polymorphic DNAs (RAPDs) using 16 random 10-mer primers. Polymorphism within populations varied from 20% to 31%. At the interpopulation level, 111/149 (74%) of RAPDs were polymorphic. Restriction fragment length polymorphism (RFLP) analysis of 21 individuals (3 individuals randomly selected from the 7 populations) using 30 probe-enzyme combinations revealed a high level of interpopulation polymorphism (62.2%) indicating interpopulation genetic divergence. The polymorphic RAPDs and RFLPs were pooled, and clustering was carried out based on mean similarity for individual populations. The dendrogram showed groupings of populations from the West and East Coasts of India into separate clusters, at 60% similarity level. Further, RAPD and RFLP analysis of male and female plants showed approximately the same level of variation in both sexes, and no sex-linked markers were found. These results demonstrate that considerable intrapopulation and interpopulation genetic variations exist in E. agallocha, and that lack of genetic variation is not the reason for the morphological uniformity observed across the range of the species.     

Importance of colour in the reaction of passerine predators to aposematic prey: experiments with mutants of Pyrrhocoris apterus (Heteroptera)

Persistent questions concerning the warning coloration of unpalatable insects address whether the bright aposematic colour itself or its combination with a species-specific dark pattern is the key factor in their protection against insectivorous birds, and how chromatic polymorphism originates and is maintained in aposematics. In the present study, these questions were tested experimentally, using the birds Parus major , Parus caeruleus , Erithacus rubecula , and Sylvia atricapilla as predators, and chromatically polymorphic firebug Pyrrhocoris apterus : red wild form, white, yellow, and orange mutants (all four of them with the same black melanin pattern, the mutants differing in colour of pteridine pigments only) and the nonaposematic brown-painted wild form as prey. The results show that a specific colour is essential for the birds to recognize the specific aposematic prey; the melanin pattern is not sufficient. White mutants were no better protected than nonaposematic firebugs; red wild-type and orange mutants were equally well protected against all bird species; and the reaction of birds to yellow mutants was species-specific. An evolutionary scenario of 'recurrent recessive mutations' is formulated to explain the origin of colour polymorphism in some aposematics.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 143–153.     

Identification of the e allele at the Extension locus (MC1R) in Brazilian Creole sheep and its role in wool color variation

The melanocortin 1 receptor (MC1R) gene has been described as responsible for the black color in some breeds of sheep, but little is known about its function in many colored breeds, particularly those with a wide range of pigmentation phenotypes. The Brazilian Creole is a local breed of sheep from southern Brazil that has a wide variety of wool colors. We examined the MC1R gene (Extension locus) to search for the e allele and determine its role in controlling wool color variation in this breed. One hundred and twenty-five animals, covering the most common Creole sheep phenotypes (black, brown, dark gray, light gray, and white), were sequenced to detect the mutations p.M73K and p.D121N. Besides these two mutations, three other synonymous sites (429, 600, and 725) were found. The dominant allele (E(D): p.73K, and p.121N) was found only in colored animals, whereas the recessive allele (E(+): p.73M, and p.121D) was homozygous only in white individuals. We concluded that MC1R is involved in the control of wool color in Brazilian Creole sheep, particularly the dark phenotypes, although a second gene may be involved in the expression of the white phenotype in this breed.     

Geographical variation in the genitalia of three species of Cicadellidae (Hemiptera)

Specimens of three species of Cicadellidae, Agallia laevis Ribaut, Eupteryx stachydearum Hardy and E.urticae Fabricius, are examined from different parts of their distribution in Europe and differences in genital characters are recorded. Variation in Agallia laevis suggests a dine or stepped cline from S.E. to N.W. in the shape of the anal appendages and aedeagus, while E. stachydearum shows a N–S cline, and a similar altitudinal cline, in the length and curvature of the apical processes of the aedeagus. In E.urticae geographical variation in the size and direction of the same processes also clearly occurs, though the exact pattern is not yet clear.     

Inheritance of trunk banding in the tetra (Gymnocorymbus ternetzi Characidae)

The tetra (Gymnocorymbus ternetzi) exhibits two phenotypes associated with trunk banding. Fish possess either a smoky-gray coloration with two prominent black vertical bands located directly behind the operculum (black tetra) or a lighter coloration and lack these bands (white skirt tetra). Segregation patterns observed from the progenies of 11 different crosses suggest that the inheritance of these phenotypes is controlled by two autosomal loci acting in a complementary fashion, with dominance at both loci required for the expression of the darker, banded phenotype.     

Gene genealogies reveal differentiation at sex pheromone olfactory receptor loci in pheromone strains of the European corn borer, Ostrinia nubilalis

Males of the E and Z strains of the European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) are attracted to different blends of the same pheromone components. The difference in male behavioral response is controlled by the sex-linked locus Resp. The two types of males have identical neuroanatomy but their physiological specificity is reversed, suggesting that variation at the periphery results in behavioral change. Differences in the olfactory receptors (ORs) could explain the strain-specific antennal response and blend preference. Gene genealogies can provide insights into the processes involved in speciation and allow delineation of genome regions that contribute to reproductive barriers. We used intronic DNA sequences from five OR-encoding genes to investigate whether they exhibit fixed differences between strains and therefore might contribute to reproductive isolation. Although two genealogies revealed shared polymorphism, molecular polymorphism at three genes revealed nearly fixed differences between strains. These three OR genes map to the sex chromosome, but our data indicate that the distance between Resp and the ORs is >20 cM, making it unlikely that variation in pheromone-sensitive OR genes is directly responsible for the difference in behavioral response. However, differences in male antennal response may have their origin in the selection of strain-specific alleles.     

Promoter polymorphisms of hepatic lipase gene influence HDL(2) but not HDL(3) in African American men: CARDIA study

Hepatic lipase encoded by the hepatic lipase gene (LIPC) is involved in the metabolism of several lipoproteins. Four promoter polymorphisms in LIPC have been found to be in complete disequilibrium and associated with high density lipoprotein cholesterol (HDL-C) and apolipoprotein (apo)A-I levels in both white and black populations. We investigated the association between the promoter polymorphism and lipid profiles as well as anthropometric phenotypes in African American men in the Coronary Artery Risk Development in Young Adults study. We performed serial cross-sectional analyses and longitudinal analyses of lipids from 578 subjects in five examinations over 10 years of follow-up. Results showed that the allele frequency (0.52) in our black population was consistent with that reported in black subjects but much higher than that reported (approximately 0.2) in white populations. Analysis of covariance tests of the three genotypic means in each examination showed that the P values ranged from 0.01 to 0.08 for HDL-C (except P = 0.54 in the fourth examination), from 0.006 to 0.01 for HDL(2)-C, and from 0.06 to 0.07 for apoA-I. Mean HDL(3)-C levels were essentially identical among the three genotypes. Total cholesterol, low density lipoprotein cholesterol (LDL-C), triglycerides, and apoB, which are mainly involved in the very low density lipoprotein-LDL pathway, were not significantly different according to the promoter polymorphism, except for triglycerides in the third examination (P = 0.01). No significant association was found between anthropometric phenotypes and the LIPC polymorphism in any of five examinations. The change of the anthropometric variables was not significantly associated with genotypes. In conclusion, our results indicated that the LIPC promoter polymorphism has exclusive effects on HDL(2)-C but not HDL(3)-C levels.     

Identification of the nucleotide substitution that generates the fourth polymorphic site in human deoxyribonuclease I (DNase I)

In addition to the three polymorphic sites responsible for protein polymorphism, a new polymorphic site has been identified in intron 7 of the human deoxyribonuclease I (DNase I) gene. Three phenotypes were observed on single-strand conformational polymorphism analysis of a 266-bp polymerase chain reaction-amplified fragment containing exon 7 and part of intron 7 of the human DNase I gene. DNA sequencing analysis demonstrated that a C-G substitution occurred at position 1978 in intron 7. This substitution was confirmed by restriction fragment length polymorphism analysis, since a new Msp1 site is created by the substitution. Population and family studies showed that the inheritance of the genotypes for DNase I C1978G polymorphism is controlled by two codominant alleles, tentatively designated DNASE1*1978C and *1978G. The gene frequencies in a Japanese population were significantly different from those in a Caucasian (German) population. The C1978G polymorphism is in linkage disequilibrium with the common DNase I protein phenotypes 1, 1–2, and 2. Received: 20 March 1996 / Revised: 14 May 1996     

Genetical control of phosphoglucose isomerase isozymes in the Japanese quail erythrocytes

Three phenotypes of phosphoglucose isomerase (PGI) from the Japanese quail erythrocytes were observed by horizontal starch gel electrophoresis. Population and family data from one laboratory population of quail was consistent with the theory that PGI polymorphism was controlled by two codominant, autosomal alleles designated PGI^F and PGI^S with gene frequency values 0.25 and 0.75, respectively. The study supported the earlier view that the Japanese quail is highly polymorphic with regard to biochemical variation.     

RAPDs as an aid to evaluate the genetic integrity of somatic embryogenesis-derived populations of Picea mariana (Mill.) B.S.P.

Summary The usefulness of random amplified polymorphic DNA (RAPD) in assessing the genetic stability of somatic embryogenesis-derived populations of black spruce [Picea mariana (Mill.) B.S.P.] was evaluated. Three arbitrary 11-mer primers were successfully used to amplify DNA from both in-vivo and in-vitro material. Twenty-five embryogenic cell lines, additional zygotic embryos and megagametophytes from three controlled crosses involving four selected genotypes of black spruce were used for the segregation analysis of RAPD variants. Ten markers were genetically characterized and used to evaluate the genetic stability of somatic embryos derived from three embryogenic cell lines (one cell line per cross, 30 somatic embryos per cell line). No variation was detected within clones. The utilization of RAPD markers both for the assessment of genetic stability of clonal materials and to certify genetic stability throughout the process of somatic embryogenesis is discussed.     

Opsin gene polymorphism predicts trichromacy in a cathemeral lemur

Recent research has identified polymorphic trichromacy in three diurnal strepsirrhines: Coquerel's sifaka (Propithecus coquereli), black and white ruffed lemurs (Varecia variegata), and red ruffed lemurs (V. rubra). Current hypotheses suggest that the transitions to diurnality experienced by Propithecus and Varecia were necessary precursors to their independent acquisitions of trichromacy. Accordingly, cathemeral lemurs are thought to lack the M/L opsin gene polymorphism necessary for trichromacy. In this study, the M/L opsin gene was sequenced in ten cathemeral blue-eyed black lemurs (Eulemur macaco flavifrons). This analysis identified a polymorphism identical to that of other trichromatic strepsirrhines at the critical amino acid position 285 in exon 5 of the M/L opsin gene. Thus, polymorphic trichromacy is likely present in at least one cathemeral Eulemur species, suggesting that strict diurnality is not necessary for trichromacy. The presence of trichromacy in E. m. flavifrons suggests that a re-evaluation of current hypotheses regarding the evolution of strepsirrhine trichromacy may be necessary. Although the M/L opsin polymorphism may have been independently acquired three times in the lemurid-indriid clade, the distribution of opsin alleles in lemurids and indriids may also be consistent with a common origin of trichromacy in the last common ancestor of either the lemurids or the lemurid-indriid clade.     

Genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism

Many polyphenisms are examples of adaptive phenotypic plasticity where a single genotype produces distinct phenotypes in response to environmental cues. Such alternative phenotypes occur as winged and wingless parthenogenetic females in the pea aphid (Acyrthosiphon pisum). However, the proportion of winged females produced in response to a given environmental cue varies between clonal genotypes. Winged and wingless phenotypes also occur in males of the sexual generation. In contrast to parthenogenetic females, wing production in males is environmentally insensitive and controlled by the sex-linked, biallelic locus, aphicarus (api). Hence, environmental or genetic cues induce development of winged and wingless phenotypes at different stages of the pea aphid life cycle. We have tested whether allelic variation at the api locus explains genetic variation in the propensity to produce winged females. We assayed clones from an F2 cross that were heterozygous or homozygous for alternative api alleles for their propensity to produce winged offspring. We found that clones with different api genotypes differed in their propensity to produce winged offspring. The results indicate genetic linkage of factors controlling the female wing polyphenism and male wing polymorphism. This finding is consistent with the hypothesis that genotype by environment interaction at the api locus explains genetic variation in the environmentally cued wing polyphenism.     

Development of microsatellite primers of the largest seagrass, Enhalus acoroides (Hydrocharitaceae)

? Premise of the study: Microsatellite primers were developed for the seagrass Enhalus acoroides to investigate genetic variation and identify clonal structure. ? Methods and Results: Four polymorphic loci and 32 monomorphic loci were developed in E. acoroides. Two to four alleles per locus were observed at the polymorphic loci across 60 individuals of two E. acoroides populations. The observed and expected heterozygosities within populations ranged from 0.100 to 0.5667 and from 0.0977 to 0.5079, respectively. ? Conclusions: Our study revealed very low polymorphism in E. acoroides, even at the polymorphic loci. Nevertheless, these primers are a useful tool to study genetic variation, clonal structure, and mating system.     

Two-dimensional electrophoresis of horse serum proteins: genetic polymorphism of ceruloplasmin and two other serum proteins

Two-dimensional agarose gel (pH 8.6)-horizontal polyacrylamide gel (pH 9.0) electrophoresis of horse serum proteins revealed genetic polymorphism of ceruloplasmin (Cp) and two unidentified serum proteins tentatively designated serum protein 1 (SP1) and serum protein 2 (SP2). Family data were consistent with the hypothesis that the observed Cp and SP1 phenotypes were each controlled by two co-dominant, autosornal alleles. The three common SP2 phenotypes were shown to be controlled by two codominant, autosomal alleles. Population data and limited family data indicated the occurrence of two additional SP2 alleles. Altogether more than 600 horses representing 13 different breeds were typed for Cp, SP1 and SP2, and allele frequency estimates were calculated. SP2 was highly polymorphic in all breeds studied whereas SP1 and Cp showed quite low degrees of polymorphism. SP1 polymorphism was observed in seven breeds while Cp polymorphism was observed only in the Icelandic toelter horse breed.