FReD: the floral reflectance database--a web portal for analyses of flower colour

Background

Flower colour is of great importance in various fields relating to floral biology and pollinator behaviour. However, subjective human judgements of flower colour may be inaccurate and are irrelevant to the ecology and vision of the flower''s pollinators. For precise, detailed information about the colours of flowers, a full reflectance spectrum for the flower of interest should be used rather than relying on such human assessments.

Methodology/Principal Findings

The Floral Reflectance Database (FReD) has been developed to make an extensive collection of such data available to researchers. It is freely available at http://www.reflectance.co.uk. The database allows users to download spectral reflectance data for flower species collected from all over the world. These could, for example, be used in modelling interactions between pollinator vision and plant signals, or analyses of flower colours in various habitats. The database contains functions for calculating flower colour loci according to widely-used models of bee colour space, reflectance graphs of the spectra and an option to search for flowers with similar colours in bee colour space.

Conclusions/Significance

The Floral Reflectance Database is a valuable new tool for researchers interested in the colours of flowers and their association with pollinator colour vision, containing raw spectral reflectance data for a large number of flower species.     

The Hemipepsis wasp‐pollination system in South Africa: a comparative analysis of trait convergence in a highly specialized plant guild

Pollinator‐mediated convergence in floral traits is the fundamental basis for pollination syndromes, but it has seldom been rigorously analysed. Here we synthesize information on a guild of South African plants that are pollinated by functionally similar pompilid wasps in the genus Hemipepsis and investigate the extent of trait convergence in guild members. The guild includes members from three plant families (Apocynaceae, Orchidaceae and Asparagaceae subfamily Scilloideae) and contains remarkably high levels of functional specialization with 18 of the 23 known guild members being pollinated exclusively by Hemipepsis wasps. The distribution of the guild is centred in the moist upland grasslands of eastern South Africa. Qualitative similarities among guild members include dull greenish‐ or brownish‐white flowers, often with purple blotches, mid‐summer flowering, sweet spicy scent and exposed nectar. To assess the extent of convergent evolution within the guild, we compared floral traits of guild members with those of congeneric non‐wasp‐pollinated species. Guild members typically produce moderate volumes (> 4 µL per flower per day) of concentrated (> 50% sugar by weight) sucrose‐dominant nectar. The nectar properties of guild members did not, however, differ significantly from those of congeneric species pollinated by other vectors. Non‐metric multidimensional scaling of scent data for 15 guild members and 17 congeners (obtained through gas chromatography–mass spectrometry of headspace samples and supplemented with published data) yielded little evidence for convergent evolution in the overall scent composition of guild members. However, convergence in floral spectral reflectance was evident in the guild members; in particular, loci for colours of guild members were significantly closer to the guild centroid than loci for colours of congeners, and they formed a distinct cluster in the blue to blue–green region of the hymenopteran colour hexagon. The colours of guild members were also significantly closer to the colour of background vegetation than those of congeneric species, suggesting a role for cryptic colouring in this system. These results confirm convergence in the floral colours of plants that are pollinated by Hemipepsis spider‐hunting wasps, but also suggest that other traits, such as nectar properties, do not necessarily evolve during shifts between pollination systems. Identification of particular scent compounds and non‐sugar nectar constituents that influence wasp behaviour will be essential for illuminating the extent of biochemical convergence in the guild members. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 278–299.     

Colour plasticity and background matching in a threespine stickleback species pair

Examining differences in colour plasticity between closely‐related species in relation to the heterogeneity of background colours found in their respective habitats may offer important insight into how cryptic colour change evolves in natural populations. In the present study, we examined whether nonbreeding dorsal body coloration has diverged between sympatric species of stickleback along with changes in habitat‐specific background colours. The small, limnetic species primarily occupies the pelagic zone and the large, benthic species inhabits the littoral zone. We placed benthic and limnetic sticklebacks against extremes of habitat background colours and measured their degree of background matching and colour plasticity. Benthics matched the littoral background colour more closely than did the limnetics, although there was no difference between species in their resemblance to the pelagic background colour. Benthics were able to resemble both background colours by exhibiting greater directional colour plasticity in their dorsal body coloration than limnetics, which may be an adaptive response to the greater spectral heterogeneity of the littoral zone. The present study highlights how habitat‐specific spectral characteristics may shape cryptic coloration differences between stickleback species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 902–914.     

Morphological and plumage colour variation in the Réunion grey white‐eye (Aves: Zosterops borbonicus): assessing the role of selection

The Réunion grey white‐eye (Zosterops borbonicus), a small passerine endemic to the island of Réunion (Mascarene archipelago), constitutes an extraordinary case of phenotypic variation within a bird species, with conspicuous plumage colour differentiation at a microgeographical scale. To understand whether natural selection could explain such variability, we compared patterns of variation in morphological and plumage colour traits within and among populations. To quantify morphological variation, we used measurements obtained by Frank Gill in the 1960s from 239 individuals collected in 60 localities distributed over the entire island of Réunion. To quantify colour variation, we measured the reflectance spectra of plumage patches of 50 males from a subset of Gill's specimens belonging to the five recognized plumage colour variants and used a visual model to project these colours in an avian‐appropriate, tetrachromatic, colour space. We found that variants occupy different regions of the avian colour space and that between‐variant differences for most plumage patches could be discriminated by the birds. Differences in morphology were also detected, but these were, in general, smaller than colour differences. Overall, we found that variation in both plumage colour and morphology among variants is greater than would be expected if genetic drift alone was responsible for phenotypic divergence. As the plumage colour variants correspond to four geographical forms, our results suggest that phenotypic evolution in the Réunion grey white‐eye is at least partly explained by divergent selection in different habitats or regions. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 459–473.     

Thrips see red – flower colour and the host relationships of a polyphagous anthophilic thrips

Abstract 1. The common blossom thrips, Frankliniella schultzei, is a polyphagous anthophilic species that colonises a wide range of host‐plant species across different plant taxa. The environmental cues used by these polyphagous insects to recognise and locate host plants are not known. We therefore determined if colour is an important environmental signal used by F. schultzei to recognise flowers of eight of its more significant host‐plant species. 2. The effect of flower colour on the colonisation of different host plant species by F. schultzei was investigated by collecting and analysing the following: (a) numbers of thrips from different heights and aspects of the primary host plant Malvaviscus arboreus, (b) thrips distribution within flowers of Hibiscus rosasinensis, (c) colour reflectance from flowers of eight different host‐plant species, and (d) reflectance from different coloured sticky traps and the number of thrips trapped on them at different times of the day and on different dates. 3. The results indicate that: (a) the thrips (both sexes) concentrate towards the top of the primary host plant M. arboreus and are not distributed differentially according to sunny or shady aspect of the plant, (b) the number of female thrips on H. rosasinensis was higher in anthers compared to petals (corolla) and the basal parts of the flower, and males were as numerous on the petals as were females, and (c) there is a common floral reflectance pattern (but with different intensities) across the eight host plant species, mainly in the red part of the spectrum (600–700 nm). 4. Results of colour sticky trapping show that red attracts more female thrips compared to any other colour and that most were caught between 09.00 and 11.00 hours. By contrast, more male thrips were trapped between 07.00 and 09.00 hours. Males were more evenly distributed across the different colours but the highest numbers were associated with the yellow traps. 5. The higher densities of thrips at the top of their host plant may be related to the early morning (07.00–11.00 hours) activity of the thrips, when the top portions of the plant are more exposed to sunlight. The sex‐related distributions of F. schultzei thrips across time, coloured sticky traps, and various parts of the flowers seem to be related to mating swarm formation by the males, on the one hand, and the relative frequency and intensity of the use of M. arboreus by the females, on the other, as a feeding and oviposition site. Frankliniella schultzei females respond more strongly to red than to any other colours, so it is predicted that the spectral properties of colour recognition by this species will correlate with the predominant red reflectance of its primary host, M. arboreus, and that there may well be a sex‐related difference in colour recognition within this species.     

Visual signalling of nectar‐offering flowers and specific morphological traits favour robust bee pollinators in the mass‐flowering tree Handroanthus impetiginosus (Bignoniaceae)

Mass flowering is a widespread blooming strategy among Neotropical trees that has been frequently suggested to increase geitonogamous pollination. We investigated the pollination ecology of the mass‐flowering tree Handroanthus impetiginosus, addressing its breeding system, the role in pollination of different visitors, the impact of nectar robbers on fruit set and the function of colour changes in nectar guides. This xenogamous species is mainly pollinated by Centris and Euglossa bees (Apidae) seeking nectar, which are known to fly long distances. The flowers favour these bees by having: (1) a closed entrance in newly opened flowers which provides access only to strong bees capable of deforming the flower tube; and (2) a nectar chamber that is accessible only to long‐tongued bees. Only first‐day flowers with yellow nectar guides produce nectar. Pollinators prefer these flowers over second‐ and third‐day flowers with orange and red nectar guides, respectively. Nectar robbers damage two‐thirds of the flowers and this robbing activity decreases fruit set by half. We attribute the low fruit set of H. impetiginosus to the intense nectar robbing and hypothesize that visual signalling of nectar presence in newly opened (receptive) flowers reduces geitonogamy by minimizing bee visits to unrewarding (non‐receptive) flowers. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 396–407.     

Defining the colour pattern phenotype in bumble bees (Bombus): a new model for evo devo

Few insects exhibit the striking colour pattern radiation found in bumble bees (Bombus), which have diversified globally into a wide range of colours and patterns. Their potent sting is often advertised by conspicuous bands of contrasting colour commonly mimicked by scores of harmless (Batesian mimics) and noxious species (Müllerian co‐mimics). Despite extensive documentation of colour pattern diversification, next to nothing is known about the genetic regulation of pattern formation in bumble bees, hindering progress toward a more general model of the evolution of colour pattern mimicry. A critical first step in understanding the colour pattern genotype is an unambiguous understanding of the phenotype under selection, which has not been objectively defined in bumble bees. Here, we quantitatively define the principal colour pattern elements that comprise the phenotype array across all species. Matrix analysis of meticulously scored colour patterns of ～95% of described species indicates there are 12 discrete primary ‘ground plan’ elements in common among all species, many of which correspond to segmentation patterning. Additional secondary elements characterize individual species and geographical variants. The boundaries of these elements appear to correspond to expression patterns of Hox genes in Drosophila and Apis but also suggest novel post‐Hox specialization of abdominal patterning. Our findings provide the first foundation for exploring candidate genes regulating adaptive pattern variation in bumble bees and broaden the framework for understanding common genetic mechanisms of pattern evolution in insects. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 384–404.     

Colour evolution within orchids depends on whether the pollinator is a bee or a fly

• Orchids are a classic angiosperm model for understanding biotic pollination. We studied orchid species within two species‐rich herbaceous communities that are known to have either hymenopteran or dipteran insects as the dominant pollinators, in order to understand how flower colour relates to pollinator visual systems.
• We analysed features of the floral reflectance spectra that are significant to pollinator visual systems and used models of dipteran and hymenopteran colour vision to characterise the chromatic signals used by fly‐pollinated and bee‐pollinated orchid species.
• In contrast to bee‐pollinated flowers, fly‐pollinated flowers had distinctive points of rapid reflectance change at long wavelengths and a complete absence of such spectral features at short wavelengths. Fly‐pollinated flowers also had significantly more restricted loci than bee‐pollinated flowers in colour space models of fly and bee vision alike.
• Globally, bee‐pollinated flowers are known to have distinctive, consistent colour signals. Our findings of different signals for fly pollination is consistent with pollinator‐mediated selection on orchid species that results from the distinctive features of fly visual systems.

     

Condition and brightness of structural blue‐green: motmot tail‐racket brightness is related to speed of feather growth in males,but not in females

Coloration plays an important role in sexual and social communication, and in many avian species both males and females maintain elaborate colours. Recent research has provided strong support for the hypothesis that elaborate female traits can be maintained by sexual or social selection; however, most research on female ornamentation has focused on pigment‐based colours, and less is known about how structural colours are maintained. Both sexes of the turquoise‐browed motmot (Eumomota superciliosa) have a blue‐green racket‐tipped tail, and it remains unknown if tail coloration serves as a sexual or social signal in one or both sexes. Here, we describe sexual dichromatism in the blue‐green portion of the tail racket, and we test for a relationship between coloration and condition, as indicated by growth bars. Tail colour of both sexes has a similar spectral shape, and there is significant, although moderate, sexual dichromatism: males are brighter than females, and males have marginally greater blue‐green saturation than females. The length of feather grown per day is positively related to overall feather brightness, but this relationship is only present in males. The relationship between male coloration and condition suggests that tail colour has the potential to convey information about individual quality during mate choice or contest competition. The lack of a similar relationship in females suggests that female tail colour does not convey the same condition‐dependent information that we suggest may be reflected by male colour. Female tail colour may therefore reflect other aspects of condition, be involved in other (non‐condition‐dependent) forms of communication, or be expressed as a non‐functional byproduct of genetic correlation between the sexes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 673–681.     

Interpreting patterns of resource utilization: randomness and selectivity in pollen feeding by adult hoverflies

Summary Adult syrphid flies feed primarily on pollen and nectar from flowers and may be regarded as suitable models for the investigation of resource partitioning in a plant/pollinator system. The present study examines the extent to which a small group of six species are selective in their diets and investigates the role of flower colour as a means by which such selectivity may occur. Flower feeding preferences were determined by pollen analyses of gut contents and an extensive flower sampling programme was under-taken to provide information on the relative abundances of the food resources available to the insects. Flower colours were defined by their reflectance spectra, and the inherent colour preferences of the flies were determined by field experiments in which natural flowers were simulated using painted plastic discs. The results reveal that some hoverfly species are highly selective in their pollen diets, while others have a more generalist approach to their foraging. The division of flower resources by the more selective species is shown to be dependent, at least partially, on the colours of the flowers. The findings are discussed in relation to the theories of Competition and Optimal Foraging and the mechanistic approach to ecology. The use of learning models is suggested as an alternative means of investigating patterns of resource use in future research.     

Red oilseed rape? The potential for manipulation of petal colour in control strategies for the pollen beetle (Meligethes aeneus)

The pollen beetle (Meligethes aeneus) is a major pest of oilseed rape (Brassica napus) at the inflorescence stage and is well known to prefer colours called yellow by human observers over many other colours. While commercial cultivars of oilseed rape have yellow flowers, little is known about the potential to manipulate host plant location and reduce subsequent infestation by this pest through variation in flower colour. We investigated the responses of pollen beetles to flowers of a white-petalled oilseed rape variety that had been dyed different colours in semi-field arena and field experiments. Flowers dyed blue or red were less heavily infested than those dyed yellow or the white flowers, indicating that blue and red flowers were less attractive than yellow and white ones. This response was most likely due to differences in petal colour because olfactometer studies showed that beetle responses to the odours of the coloured treatments did not differ. The comparatively high infestation of untreated white flowers is interpreted as a consequence of their high UV reflectance; the presence of a UV receptor in M. aeneus is suggested, and its role in visually guided insect–plant interactions in this species described. The potential for manipulation of petal colour in control strategies for the pollen beetle is discussed.     

Flower colours along an alpine altitude gradient, seen through the eyes of fly and bee pollinators

Alpine flowers face multiple challenges in terms of abiotic and biotic factors, some of which may result in selection for certain colours at increasing altitude, in particular the changing pollinator species composition, which tends to move from bee-dominated at lower elevations to fly-dominated in high-alpine regions. To evaluate whether growing at altitude—and the associated change in the dominant pollinator groups present—has an effect on the colour of flowers, we analysed data collected from the Dovrefjell National Park in Norway. Unlike previous studies, however, we considered the flower colours according to ecologically relevant models of bee and fly colour vision and also their physical spectral properties independently of any colour vision system, rather than merely looking at human colour categories. The shift from bee to fly pollination with elevation might, according to the pollination syndrome hypothesis, lead to the prediction that flower colours should shift from more bee-blue and UV-blue flowers (blue/violet to humans, i.e. colours traditionally associated with large bee pollinators) at low elevations to more bee-blue-green and green (yellow and white to humans—colours often linked to fly pollination) flowers at higher altitude. However, although there was a slight increase in bee-blue-green flowers and a decrease in bee-blue flowers with increasing elevation, there were no statistically significant effects of altitude on flower colour as seen either by bees or by flies. Although flower colour is known to be constrained by evolutionary history, in this sample we also did not find evidence that phylogeny and elevation interact to determine flower colours in alpine areas. Handling editor: Neal Williams     

Stable correlation structure among multiple plumage colour traits: can they work as a single signal?

The presence of multiple distinct ornamental traits in the same species is frequently explained by context‐specificity and different information content. However, the expression of multiple ornaments is often correlated, and such traits may therefore function as a single, integrated signal. Delayed use of an integrated signal relative to production requires temporal stability in integration, which has seldom been examined. We used autumn and spring reflectance data from the breast, breast stripe, and crown of great tits (Parus major) to assess the stability and mating implications of colour signal integration, as well as the repeatability of any integrated colour trait and its correlation with condition during moult. We found high levels of stability between seasons, years, sexes, and ages in the correlation patterns of colour measures across the three plumage areas. The first principal component colour axis described joint variation of ultraviolet (UV) reflectance on the crown and the breast stripe, thereby representing an among‐trait UV chroma axis. However, only breast yellow chroma showed condition‐dependence, whereas temporally consistent and significant assortative mating was restricted to crown UV chroma. Our results therefore do not support the idea that the overall UV chroma of the breast stripe and the crown is special in condition‐dependence and repeatability, or that it plays a specific role in mutual sexual selection as an integrated signal. The results show that stable association between display traits is an existing phenomenon. They also indicate that, even in the presence of correlated traits, functional trait integration among these requires further scrutiny. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 92–108.     

Biological significance of distinguishing between similar colours in spectrally variable illumination: bumblebees (<Emphasis Type="Italic">Bombus terrestris</Emphasis>) as a case study

Individual bumblebees were trained to choose between rewarded target flowers and non-rewarded distractor flowers in a controlled illumination laboratory. Bees learnt to discriminate similar colours, but with smaller colour distances the frequency of errors increased. This indicates that pollen transfer might occur between flowers with similar colours, even if these colours are distinguishable. The effect of similar colours on reducing foraging accuracy of bees is evident for colour distances high above discrimination threshold, which explains previous field observations showing that bees do not exhibit complete flower constancy unless flower colour between species is distinct. Bees tested in spectrally different illumination conditions experienced a significant decrease in their ability to discriminate between similar colours. The extent to which this happens differs in different areas of colour space, which is consistent with a von Kries-type model of colour constancy. We find that it would be beneficial for plant species to have highly distinctive colour signals to overcome limitations on the bees performance in reliably judging differences between similar colours. An exception to this finding was flowers that varied in shape, in which case bees used this cue to compensate for inaccuracies of colour vision.     

Parallel evolution of angiosperm colour signals: common evolutionary pressures linked to hymenopteran vision

Flowering plants in Australia have been geographically isolated for more than 34 million years. In the Northern Hemisphere, previous work has revealed a close fit between the optimal discrimination capabilities of hymenopteran pollinators and the flower colours that have most frequently evolved. We collected spectral data from 111 Australian native flowers and tested signal appearance considering the colour discrimination capabilities of potentially important pollinators. The highest frequency of flower reflectance curves is consistent with data reported for the Northern Hemisphere. The subsequent mapping of Australian flower reflectances into a bee colour space reveals a very similar distribution of flower colour evolution to the Northern Hemisphere. Thus, flowering plants in Australia are likely to have independently evolved spectral signals that maximize colour discrimination by hymenoptera. Moreover, we found that the degree of variability in flower coloration for particular angiosperm species matched the range of reflectance colours that can only be discriminated by bees that have experienced differential conditioning. This observation suggests a requirement for plasticity in the nervous systems of pollinators to allow generalization of flowers of the same species while overcoming the possible presence of non-rewarding flower mimics.     

Colour and size of flowers in relation to pollination of Erica species

Summary Data on flower colour polymorphism were recorded for 341 of some 426 species of Erica occurring in the south-western Cape, South Africa. Thirty-eight per cent of these Erica species are colour polymorphic, the incidence of polymorphism being greater than expected for ornithophilous species and lower than expected for anemophilous species. Both altitude and season of flowering are correlated with the incidence of colour polymorphism, with most polymorphs occurring in species which have relatively large altitudinal ranges and extended flowering periods. The mean corolla length for each of pink, purple and white flowers is significantly shorter than that for each of red, orange, yellow and green flowers, suggesting that these two sets of colours correspond with entomophily and ornithophily, respectively. There are no Erica species with blue flowers. We suggest that the patterns of colour polymorphism, because of their relationships with the behaviour of pollinators, may reflect patterns of speciation in the genus.     

Staminal hairs enhance fecundity in the pollen‐rewarding self‐incompatible lily Bulbine abyssinica

Flowering plants typically use floral rewards to attract animal pollinators. Unlike nectar, pollen rewards are usually visible and may thus function as a signal that influences landing decisions by pollen‐seeking insects. Here we artificially manipulate the presence of both pollen and staminal hairs (a putative false signal of pollen reward availability) in the hermaphroditic lily Bulbine abyssinica (Xanthorrhoeaceae) to investigate their effects on bee visitation and fecundity, and also test for trade‐offs between pollen production and seed production. Honeybees, the primary floral visitors, are probably not able to distinguish between colours of petals, staminal hairs and pollen of B. abyssinica, according to analysis of reflectance spectra in a bee vision model. Flowers with both pollen and hairs removed had the lowest levels of bee visitation, seed set and seed abortions. Flowers containing hairs had an ～50% increase in visitation rate and seed set compared with emasculated flowers, while intact controls had the highest seed abortion rate. Ovule discounting in intact flowers is probably due to ovarian self‐incompatibility (or strong early inbreeding depression) as ovules penetrated by tubes from self‐pollen uniformly failed to develop into seeds. These results show that staminal hairs can enhance plant fecundity by increasing attraction of pollen‐seeking insects to flowers without increasing the risk of ovule discounting through pollinator‐mediated self‐pollination. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 481–490.     

Lack of association between winter coat colour and genetic population structure in the Japanese hare,Lepus brachyurus (Lagomorpha: Leporidae)

Seasonal changes in fur colour in some mammalian species have long attracted the attention of biologists, especially in species showing population variation in these seasonal changes. Genetic differences among populations that show differences in seasonal changes in coat colour have been poorly studied. Because the Japanese hare (Lepus brachyurus) has two allopatric morphotypes that show remarkably different coat colours in winter, we examined the population genetic structure of the species using partial sequences of the SRY gene and six autosomal genes: three coat colour‐related genes (ASIP, TYR, and MC1R) and three putatively neutral genes (TSHB, APOB, and SPTBN1). The phylogenetic tree of SRY sequences exhibited two distinct lineages that diverged approsimately 1 Mya. Although the two lineages exhibited a clear allopatric distribution, it was not consistent with the distribution of morphotypes. In addition, six nuclear gene sequences failed to reveal genetic differences between morphotypes. Population network trees for 11 expedient populations divided the populations into four groups. Genetic structure analysis revealed an admixture of four genetic clusters in L. brachyurus, two of which showed large genetic differences. Our results suggest ancient vicariance in L. brachyurus, and we detected no genetic differences between the two morphotypes. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 761–776.     

Optimising coloured pan traps to survey flower visiting insects

Colour is an important attractant for many flower-visiting insects (anthophiles). Consequently, coloured pan trapping is an efficient technique that can be easily and cost-effectively used to quantitatively sample assemblages of anthophiles. However, colour preferences of anthophiles is an important source of bias that needs to be considered in pan trap surveys. By drawing sub samples comprised of different colour combinations from a database of pan trap surveys in the lowlands of the Cape Floristic Region, we examine the effects of colour on pan trap catches and determine which combinations of colours might provide better estimates of diversity when sampling with multi-colour sets of pan traps. Pan trap catches included the major groups of anthophiles in the region (Coleoptera, Diptera and Hymenoptera), but butterflies (Lepidoptera) were strongly under-represented. Colour played an important role in determining the species richness and composition of pan trap catches, with colour sets that included high reflectance yellow and white generally having catches with the highest species richness. While all colour combinations provided reasonable estimates of proportional species richness, proportional abundance of taxa varied among different colour sets, and did not accurately reflect actual proportions of different taxa in the entire dataset. For comparative biodiversity surveys and assessments we recommend the use of high reflectance colours such as white and yellow traps, while for full inventory surveys, it may be necessary to include other colours to catch rarer species that are excluded by the high reflectance colours alone.     

Population genetics, phylogeography and speciation of Cystodytes (Ascidiacea) in the western Mediterranean Sea

Several morphotypes that so far have been attributed to the allegedly cosmopolitan ascidian Cystodytes dellechiajei occur in the Mediterranean Sea. Colour variation is the difference most frequently reported. In this study, we addressed the genetic structure of this ascidian in relation to geographical location and colour morph. Partial sequences of the gene cytochrome  c oxidase subunit 1 (COI) were obtained from seven populations of the western Mediterranean, encompassing eight colour varieties. All population genetic analyses (exact test, pairwise F _ST, hierarchical analysis of molecular variance, multidimensional scaling, nested clade analysis) indicated clearly that differences between colour morphs are large enough to obscure any geographical differentiation when colours are combined within localities. When variance due to colour divergence was removed, however, a significant geographical variability between localities remained. The genetic divergence between the colour morphs analysed was significant in comparisons of the brown and purple forms with the others, but not among the green, blue, and white morphs. Phylogeographic analyses suggest that population fragmentation and range expansions have shaped the present-day distribution of the haplotypes. Taken together with existing chemotype information, our results indicate that several species are present in the area, and that a thorough revision of the genus is necessary.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 203–214.