Yellow Morph Research Articles

Foraging Benefits in a Colour Polymorphic Neotropical Orb Web Spider

AbstractConspicuous body colouration in sedentary predators such as orb web spiders seems paradoxical as potential prey can see and avoid the webs. Several studies have demonstrated that rather than deterring prey, the colours act as sensory traps for flower‐seeking insects. In chromatically polymorphic species, the existence of more than one colour morph may lead to differing levels of prey attraction. To explore these issues, we studied a neotropical orb web spider, Verrucosa arenata, which shows colour polymorphism with predominantly white or yellow abdomen colours. We asked whether a particular morph is dominant in the population, and whether a particular morph is associated with enhanced foraging success and body condition. Here we showed that although yellow morphs attracted more prey, white morphs were in better body condition. We showed that model prey such as honeybees are able to discriminate between the morphs. We discuss these findings in relation to the functional significance of bright body colouration and colour polymorphism in spiders.

Transcriptome profiling of natural dichromatism in the annual fishes Nothobranchius furzeri and Nothobranchius kadleci.

BackgroundThe annual fish Nothobranchius furzeri is characterized by a natural dichromatism with yellow-tailed and red-tailed male individuals. These differences are due to different distributions of xanthophores and erythrophores in the two morphs. Previous crossing studies have showed that dichromatism in N. furzeri is inherited as a simple Mendelian trait with the yellow morph dominant over the red morph. The causative genetic variation was mapped by linkage analysis in a chromosome region containing the Mc1r locus. However, subsequent mapping showed that Mc1r is most likely not responsible for the color difference in N. furzeri. To gain further insight into the molecular basis of this phenotype, we performed RNA-seq on F2 progeny of a cross between N. furzeri male and N. kadleci female.ResultsWe identified 210 differentially-expressed genes between yellow and red fin samples. Functional annotation analysis revealed that genes with higher transcript levels in the yellow morph are enriched for the melanin synthesis pathway indicating that xanthophores are more similar to melanophores than are the erythrophores. Genes with higher expression levels in red-tails included xanthine dehydrogenase (Xdh), coding for a biosynthetic enzyme in the pteridine synthesis pathway, and genes related to muscle contraction. Comparison of DEGs obtained in this study with genes associated with pigmentation in the Midas cichlid (A. citrinellus) reveal similarities like involvement of the melanin biosynthesis pathway, the genes Ptgir, Rasef (RAS and EF-hand domain containing), as well as genes primarily expressed in muscle such as Ttn and Ttnb (titin, titin b).ConclusionsRegulation of genes in the melanin synthetic pathway is an expected finding and shows that N. furzeri is a genetically-tractable species for studying the genetic basis of natural phenotypic variations. The current list of differentially-expressed genes can be compared with the results of fine-mapping, to reveal the genetic architecture of this natural phenotype. However, an evolutionarily-conserved role of muscle-related genes in tail fin pigmentation is novel finding and interesting perspective for the future.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-754) contains supplementary material, which is available to authorized users.

Positive effect of the yellow morph on female reproductive success in the flower colour polymorphic Iris lutescens (Iridaceae), a deceptive species.

The deceptive Iris lutescens (Iridaceae) shows a heritable and striking flower colour polymorphism, with both yellow- and purple-flowered individuals growing sympatrically. Deceptive species with flower colour polymorphism are mainly described in the family Orchidaceae and rarely found in other families. To explain the maintenance of flower colour polymorphism in I.lutescens, we investigated female reproductive success in natural populations of southern France, at both population and local scales (within populations). Female reproductive success was positively correlated with yellow morph frequency, at both the population scale and the local scale. Therefore, we failed to observe negative frequency-dependent selection (NFDS), a mechanism commonly invoked to explain flower colour polymorphism in deceptive plant species. Flower size and local flower density could also affect female reproductive success in natural populations. Pollinator behaviour could explain the positive effect of the yellow morph, and our results suggest that flower colour polymorphism might not persist in I.lutescens, but alternative explanations not linked to pollinator behaviour are discussed. In particular, NFDS, although an appealingly simple explanation previously demonstrated in orchids, may not always contribute to maintaining flower colour polymorphism, even in deceptive species.

The phylogeography of red and yellow coppersmith barbets (Aves: Megalaima haemacephala)

Understanding the evolution of color in birds is important because it is used for both inter- and intra-specific communication and is often linked to other important traits including life history, behavior, immunology and mate choice. The coppersmith barbet (Megalaima haemacephala) is widely distributed across southern Asia and many islands of the Sunda shelf and the Philippines. It occurs in two well-differentiated and completely allopatric color morphs, a red- and a yellow-headed form. We constructed a phylogeny of coppersmith barbets from both color morphs and from across their range using sequences from two mitochondrial and one nuclear loci. Strong geographical patterns were found, in which India and Sri Lanka, the Philippines and mainland tropical east Asia (TE Asia), and the islands on the Sunda shelf (Sundaland) each formed a divergent group. The red birds formed two clades within the diversity of yellow animals. Major clades were dated using a molecular clock calibrated on a larger phylogeny. The phylogeographic patterns suggest that the species likely originated in TE Asia/ Sundaland and then colonized the Philippines from the south in the mid-Pleistocene, via a now extinct population on Borneo. More recently, coppersmith barbets colonized India and Sri Lanka, also from TE Asia/ Sundaland. Coppersmith barbets were also likely distributed in the past on the Malay Peninsula, but went extinct there too. The population that now inhabits this region derives from a natural recolonization of yellow morph birds about 80 years ago. The red morph evolved at least twice independently from the yellow morph in the late Pleistocene, suggesting that this change does not require very many mutational steps, and thus can arise repeatedly.

Reproductive biology and colour polymorphism in the food-deceptive Iris lutescens (Iridaceae)

Among the diversity of pollination strategies, food deception is intriguing because of the lack of rewards offered for the pollination services. Floral food deception has been frequently recorded in orchids; however, there is little evidence for food deception outside the Orchidaceae. One putative non-orchid candidate is the Mediterranean Iris lutescens, which displays an heritable polymorphism for flower colour, with yellow and purple morphs. Colour polymorphism is frequently thought to be maintained by negative frequency-dependent selection, where rare morphs are visited more frequently than common ones. Here, we present data on reproductive biology and pollination ecology of the species in the light of the deceptive pollination strategy and the maintenance of flower colour polymorphism. There was no difference in sex allocation and flowering phenology between morphs, with a blooming period early in spring. Both colour morphs are equally self-incompatible and they depend on insects for seed production. The most common visitors with pollen loads are small and large Apoids. These were observed foraging for non-existent nectar (rather than pollen) on Iris flowers. Most of them appear to learn to avoid Iris flowers as classically observed for rewardless species, and there was no evidence of an advantage for the rare morph. Instead, we found that in some populations, large bee pollinators appeared to prefer the most common morph (positive frequency-dependent selection). Iris lutescens appears to be a hitherto neglected but relevant candidate to investigate deceptive reproductive strategy and selective pressures in generalist plants.

Color Polymorphism in Spiny Spiders (Gasteracantha fornicata): Testing the Adaptive Significance of a Geographically Clinal Lure

AbstractMany sit‐and‐wait predators use conspicuous displays of color to attract prey. These displays sometimes express discrete polymorphisms; however, the adaptive drivers of such variation are not well understood. Here, we explore a previously unknown color polymorphism in the orb‐web spider Gasteracantha fornicata. We discovered that in North Queensland, Australia, female spiders exhibit dorsal bands appearing (to the human observer) either white or yellow and characterized by sigmoidal spectral curves centered on approx. 447 and 496 nm, respectively. Based on sensory drive theory, we hypothesized that morphs may be alternatively favored by the switch in ambient viewing conditions engendered by sunny vs. cloudy skies. We addressed this hypothesis indirectly by studying morph frequencies across a approx. 200 km geographic gradient of solar exposure (a surrogate for cloudiness), and by investigating the phenotypic signature of catch success via a resource stress experiment and in wild spiders. Our data indicate substantial geographic variation in morph frequency, with white morphs dominating at more cloudy northern locations. Rather than a gradual cline, morph frequency inverted mid‐way along this range and was closely fit by a logistic relationship with latitude. Experimentally restricted access to larger prey caused spiders to lose more mass than size and to exhibit less bright dorsal markings. Wild‐sampled spiders from two localities of divergent morph frequency indicated no differences in residual mass, but intriguingly, the white morph was larger and heavier (than the yellow morph) where it was relatively rare. Our data hint at negative frequency dependence, but remain broadly consistent with a sensory drive explanation based on cloudiness, and we suggest these as worthy avenues for closer investigation.

Substrate preference in a colonial spider: is substrate choice affected by color morph?

AbstractAnimals can show preference for a particular background as a way of decreasing visibility. Species with color polymorphism may have morph‐dependent background preference. I test this hypothesis on the orb‐weaving spider Parawixia bistriata. Adult females of P. bistriata present two distinct morphs characterized by brown and yellow opisthosomata. This nocturnal spider can be found in its retreat on the vegetation during the day. In order to examine whether females exhibit substrate preference dependent on their color morph, I first recorded the distribution of color morphs on different substrates (leaf and branch) and then performed a mark and release experiment. Field censuses indicated that the yellow morph was associated with leaves while the brown morph was found on either substrate type. The results of a mark and reciprocal release experiment agreed with the censuses and suggest that the two morphs differ in their association to substrate type: yellow females were associated with the leaf substrate, while brown females showed no association to a particular substrate type. Possible forces behind these differences in substrate choice are discussed.

No evidence for differential survival or predation between sympatric color morphs of an aposematic poison frog

Because variation in warning signals slows down the predator education process, aposematic theory predicts that animal warning signals should be monomorphic. Yet, warning color polytypisms are not uncommon in aposematic species. In cases where warning signal variants are separated geographically, adaptation to local predators could explain this variation. However, this cannot explain the persistence of sympatric polymorphisms in aposematic taxa. The strawberry poison frog (Oophaga pumilio) exhibits both allopatric and sympatric warning color variation in and around the Bocas del Toro archipelago of Panama. One explanation that has been proposed for the rapid diversification of O. pumilio coloration in this archipelago is low predation; if island populations have few predators, stabilizing selection would be relaxed opening the door for diversification via selection or genetic drift. Using a combination of mark-recapture and clay model studies, we tested for differences in survival and predation among sympatric red and yellow color morphs of O. pumilio from Bastimentos Island. We found no evidence for differential survival or predation in this population, despite the fact that one morph (red) is more common and widely distributed than the other (yellow). Even in an area of the island where the yellow morph is not found, predator attack rates were similar among morphs. Visual modeling suggests that yellow and red morphs are distinguishable and conspicuous against a variety of backgrounds and by viewers with different visual systems. Our results suggest that general avoidance by predators of red and yellow, both of which are typical warning colors used throughout the animal kingdom, may be contributing to the apparent stability of this polymorphism.

Colour variation in the polymorphic common wall lizard (Podarcis muralis): An analysis using the RGB colour system

Intra-specific colour variation may either reflect a discrete polymorphism, potentially related to life-history strategies; a continuous signal, which may be related to individual quality; or a combination of both. Understanding the true nature of this colour variation may thus help to identify the possible selective mechanism producing it. The common wall lizard (Podarcis muralis) exhibits polymorphic colouration, both sexes showing three pure morphs differing in throat and belly colouration (white, yellow and red) and three intermediate morphs (white-yellow, white-red, and yellow-red). In this study we used digital photography and image analysis (RGB system) to investigate colour variation among morphs, sexes and populations. We found that colouration of the six phenotypes results from the combination of three discrete colour tinges (white, red and yellow): pure morphs express a single colour, and no continuous variation exists among them. Similarly, ventral parts of the intermediate white-red and yellow-red morphs present a mixture of two discrete colours resulting from the concurrent expression in different scales of the same colours showed by the corresponding pure morphs. Finally, the white-yellow intermediates show the same colour tinge than pure yellow morph, but with a lower intensity. The finding that white-yellow lizards are smaller than all other ones suggests that they might be subadults not yet expressing the full yellow colouration. Morph colouration significantly varied among sexes, suggesting a possible role for hormone plasma levels in controlling colour expression. It is noteworthy that RGB values varied among sites, indicating that colour expression in this species holds some level of environmental plasticity. Therefore, our results confirmed the presence of discrete colour morphs, which may be genetically based in both sexes of common wall lizards. However, our findings also showed intra-individual variation in colour expression within a morph that is associated with habitat occupancy, which suggests phenotypic plasticity in morphs.

The role of elevation and soil chemistry in the distribution and ion accumulation of floral morphs of Streptanthus polygaloides Gray (Brassicaceae), a Californian nickel hyperaccumulator

Background: The flora of serpentine/ultramafic soils provides an excellent model system for the study of natural selection in plant populations. Streptanthus polygaloides is a nickel hyperaccumulator that is endemic to serpentine soils in the Sierra Nevada of California, and has four floral morphs (yellow, purple, yellow-to-purple and undulate).Aims: We investigate three hypotheses: (1) the purple morph occurs in colder, wetter climates than the yellow morph; (2) tissue–soil ionic relationships differ among morphs; and (3) morphs occur on soils with differing elemental concentrations.Methods: We queried herbarium records to investigate patterns of occurrence among the yellow and purple floral morphs, and analysed soil and tissue samples from wild populations of all four morphs.Results: The purple morph inhabited serpentine outcrops with colder temperatures and greater precipitation levels than the yellow morph. Concentrations of elements in leaf tissue and rhizosphere soil differed little among populations of the morphs, but showed substantial within-site variation.Conclusions: Our results suggest that a climatic gradient may be responsible for divergence in floral colour among populations of S. polygaloides. Because of the large within-site variation in soil and tissue elemental concentrations, plants appear to have a varied physiological response to edaphic factors, regardless of morph membership.

Colour Polymorphism and Alternative Breeding Strategies: Effects of Parent’s Colour Morph on Fitness Traits in the Common Wall Lizard

Colour polymorphism (CP) is widespread in animals, but mechanisms underlying morph evolution and maintenance are not completely resolved. In reptiles, CP is often genetically based and associated with alternative behavioural strategies, mainly in males for most cases. However, female colour morphs also display alternative reproductive strategies associated with behavioural and physiological traits, which may contribute to maintain CP in the population. Both sexes of the common wall lizard (Podarcis muralis) show three pure colour morphs, white, yellow and red. Here, we looked for the effects of male and female colour morphs on fitness traits of captive-breeding pairs. All yellow-throated females laid clutches of many small eggs and produced many light offspring, behaving as r-strategists, whereas white-throated females laid clutches of few large eggs and produced few heavy offspring, behaving as K-strategists. Red-throated females adopted a conditional Kr-strategy depending on their size/age. These basic female strategies were modulated in relation to mate morph: white females had the best fitness gain in terms of viable offspring when mated to red males; mating between yellow morphs yielded a greater breeding success than all other morph crosses, but also lighter offspring; finally, red females produced heavy progeny when paired with red or white males, and light offspring in pair with yellow males. Thus, correlation between CP and traits relevant to fitness combined with non-random mating, either assortative or disassortative, could increase the potential for CP to contribute to divergent evolution in the common wall lizard.

Pollinator‐mediated selection in a specialized hummingbird–Heliconia system in the Eastern Caribbean

Phenotypic matches between plants and their pollinators often are interpreted as examples of reciprocal selection and adaptation. For the two co-occurring plant species, Heliconia bihai and H. caribaea in the Eastern Caribbean, we evaluated for five populations over 2 years the strength and direction of natural selection on corolla length and number of bracts per inflorescence. These plant traits correspond closely to the bill lengths and body masses of their primary pollinators, female or male purple-throated carib hummingbirds (Eulampis jugularis). In H. bihai, directional selection for longer corollas was always significant with the exception of one population in 1 year, whereas selection on bract numbers was rare and found only in one population in 1 year. In contrast, significant directional selection for more bracts per inflorescence occurred in all three populations of the yellow morph and in two populations of the red morph of H. caribaea, whereas significant directional selection on corolla length occurred in only one population of the red morph and one population of the yellow morph. Selection for longer corollas in H. bihai may result from better mechanical fit, and hence pollination, by the long bills of female E. jugularis, their sole pollinator. In contrast, competition between males of E. jugularis for territories may drive selection for more bracts in H. caribaea. Competitive exclusion of female E. jugularis by territorial males also implicates pollinator competition as a possible ecological mechanism for trait diversification in these plants.

Temporal morph frequency changes in sand-dune populations ofCepaea nemoralis(L.)

Changes in morph frequency over time in sand-dune populations of Cepaea nemoralis in the British Isles have been examined using the Evolution Megalab database. Frequencies in colonies on a sand dune at Berrow, Somerset were estimated in 2008–9. This extends a survey started in 1926 by A. E. Boycott and C. Diver and continued in the mid-20th Century by B. C. Clarke and J. J. Murray. An increase in the frequency of the mid-banded morph, noted in earlier work, has continued. The apparent decrease in brown was not confirmed but the yellow frequency has increased. At a range of dunes in the British Isles, comparisons between data from the mid-20th Century and the early 21st Century indicate an increase in yellow and mid-banded morphs and a decrease in banding and brown morphs. These results differ from the overall trends derived from Europe-wide comparison of early data with Evolution Megalab data, in which banded and mid-banded increased in frequency, whereas there was no overall change in yellow. The general pattern of regional variation has been retained, although there is also high heterogeneity between samples, suggesting that a variety of factors are involved in explaining the changes. The mean shifts in frequency are consistent with climatic change over the period. Dunes are probably the most likely habitat in which to detect such a change. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108, 315–322.

Juvenal Plumage Polymorphism in Yellow Warblers Is Not Associated with Sex

Abstract. Polymorphisms of the juvenal plumage in birds have received little study in comparison to other plumages. We investigate a polymorphism in the juvenal plumage of the Yellow Warbler (Setophaga petechia) in southeastern Ontario, Canada. Yellow Warblers in juvenal plumage show either yellow or white plumage on their lower ventral surface of the neck, breast, and belly, and these differences have been speculated to be associated with sex. We tested the hypothesis that juvenal plumage color varies with sex by using blood samples to molecularly sex 10 yellow and 14 white nestlings. We found no relationship between plumage color and sex (yellow nestlings: 70% male, 30% female; white nestlings: 64% male, 36% female). Using the same 24 nestlings that we sexed, we measured feather color with a spectrometer and found that white and yellow morphs differ significantly in reflectance spectra of red and yellow chroma. Of 66 nestlings whose plumage color we visually inspected in the wild, 73% were white and 27%...

The Evolution of Primary Sexual Characters in Animals. Edited by Janet L. Leonard and Alex Córdoba‐Aguilar. Oxford and New York: Oxford University Press. $79.95. xi + 537 p.; ill.; index. ISBN: 978‐0‐19‐532555‐3. 2011.

Previous articleNext article No AccessNew Biological BooksThe Evolution of Primary Sexual Characters in Animals. Edited by Janet L. Leonard and Alex Córdoba‐Aguilar. Oxford and New York: Oxford University Press. $79.95. xi + 537 p.; ill.; index. ISBN: 978‐0‐19‐532555‐3. 2011.Göran ArnqvistGöran ArnqvistAnimal Ecology and Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden Search for more articles by this author Animal Ecology and Evolutionary Biology Centre, Uppsala University, Uppsala, SwedenPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 86, Number 2June 2011 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/659916 Views: 26Total views on this site Citations: 1Citations are reported from Crossref Copyright © 2011 by The University of Chicago Press. All rights reserved.PDF download Crossref reports the following articles citing this article:Shao-Kun Guo, Ya-Jun Gong, Jin-Cui Chen, Pan Shi, Li-Jun Cao, Qiong Yang, Ary Anthony Hoffmann, Shu-Jun Wei Increased density of endosymbiotic Buchnera related to pesticide resistance in yellow morph of melon aphid, Journal of Pest Science 93, no.44 (Jun 2020): 1281–1294.https://doi.org/10.1007/s10340-020-01248-0

Colour differentiation in a coral reef fish throughout ontogeny: habitat background and flexibility

Colour polymorphism is widespread in animals but, in contrast to other types of poly- morphism, has been little explored during ontogeny. Among coral reef fish, the surge damselfish Chrysiptera leucopoma settles in the larval stage as a yellow morph, whereas 2 colour morphs (yellow and brown) are apparent in adults at Rangiroa Atoll, French Polynesia. To understand this dimorphism, we tested, under controlled conditions, the hypotheses that: (1) environmental cues (habitat background and conspecific density) play important roles in morph differentiation during ontogeny and (2) morph colouration is reversible. Our first experiment showed that a dark habitat background induced the formation of the brown morph, while C. leucopoma larvae kept their yellow morph when placed in aquaria with a bright habitat background. Colour change from yellow to brown also occurred within the bright habitat, but only at high conspecific densities. Our second experiment showed that colour change was reversible within 15 d post-settlement, but not at the adult stage. Overall, our results highlighted that the studied polymorphism may be environmentally induced and reversible during the first post-settlement days of this coral reef fish.

Interaction between female mating preferences and predation may explain the maintenance of rare males in the pentamorphic fish Poecilia parae

Variation in mating preferences coupled with selective predation may allow for the maintenance of alternative mating strategies. Males of the South American live-bearing fish Poecilia parae fall in one of five discrete morphs: red, yellow, blue, stripe-coloured tail (parae) and female mimic (immaculata). Field surveys indicate that the red and yellow morphs are the rarest and that their rarity is consistent across years. We explored the role of variable female mating preference and selective predation by visual predators in explaining the rarity of red and yellow males, and more generally, the maintenance of this extreme colour polymorphism. We presented wild-caught P. parae females and Aequidens tetramerus, the most common cichlid predator, with the five male colour morphs in separate trials to determine mating and prey preferences, respectively. We found that a large proportion of females shared a strong preference for the rare carotenoid-based red and yellow males, but a distinct group also preferred the blue and parae morphs. The cichlid predator strongly preferred red and yellow males as prey. Together, these results suggest that the interaction between premating sexual selection favouring and predation acting against the red and yellow morphs may explain their rarity in the wild. The trade-off between sexual and natural selection, accompanied by variation in female mating preferences, may therefore facilitate the maintenance of the striking colour polymorphism in P. parae.

Intrasexual competition facilitates the evolution of alternative mating strategies in a colour polymorphic fish

BackgroundIntense competition for access to females can lead to males exploiting different components of sexual selection, and result in the evolution of alternative mating strategies (AMSs). Males of Poecilia parae, a colour polymorphic fish, exhibit five distinct phenotypes: drab-coloured (immaculata), striped (parae), structural-coloured (blue) and carotenoid-based red and yellow morphs. Previous work indicates that immaculata males employ a sneaker strategy, whereas the red and yellow morphs exploit female preferences for carotenoid-based colours. Mating strategies favouring the maintenance of the other morphs remain to be determined. Here, we report the role of agonistic male-male interactions in influencing female mating preferences and male mating success, and in facilitating the evolution of AMSs.ResultsOur study reveals variation in aggressiveness among P. parae morphs during indirect and direct interactions with sexually receptive females. Two morphs, parae and yellow, use aggression to enhance their mating success (i.e., number of copulations) by 1) directly monopolizing access to females, and 2) modifying female preferences after winning agonistic encounters. Conversely, we found that the success of the drab-coloured immaculata morph, which specializes in a sneak copulation strategy, relies in its ability to circumvent both male aggression and female choice when facing all but yellow males.ConclusionsStrong directional selection is expected to deplete genetic variation, yet many species show striking genetically-based polymorphisms. Most studies evoke frequency dependent selection to explain the persistence of such variation. Consistent with a growing body of evidence, our findings suggest that a complex form of balancing selection may alternatively explain the evolution and maintenance of AMSs in a colour polymorphic fish. In particular, this study demonstrates that intrasexual competition results in phenotypically distinct males exhibiting clear differences in their levels of aggression to exclude potential sexual rivals. By being dominant, the more aggressive males are able to circumvent female mating preferences for attractive males, whereas another male type incorporates subordinate behaviours that allow them to circumvent male aggression and female mating preferences. Together, these and previous results indicate that exploiting different aspects of social interactions may allow males to evolve distinct mating strategies and thus the long term maintenance of polymorphisms within populations.

The historical frequency of head-colour morphs in the Gouldian Finch (Erythrura gouldiae)

The endangered Gouldian Finch (Erythura gouldiae) possesses a genetic colour polymorphism in the form of three genetically determined head-colours (yellow, black and red) that coexist in the same population. The spatial and temporal pattern of morph ratios within this species provides insight into the selective pressures acting on and maintaining the different forms. To investigate spatial and temporal patterns in the relative historical abundance of the different Gouldian Finch morphs, we surveyed museum collections around the world, identifying 614 wild-caught skins and obtaining accurate data on the morphs of 552 of these. The yellow morph was found at very low numbers (only 15 skins), consistent with its rarity in contemporary populations. Red-and black-morph individuals were found at relatively constant ratios across the geographical range over which they were sampled, and across the 140-year period during which these skins were collected, although this differed slightly for males and females (males: 62.6% black, 37.4% red; females: 79.1% black, 20.9% red). Spatial and temporal stability in the frequency of alternative morphs is extremely rare. These results suggest that the genetic architecture underlying the trait and selective pressures acting on the separate morphs of the Gouldian Finch differ between the sexes, but are fairly constant across highly variable environmental conditions.

No barriers to gene flow among sympatric polychromatic ‘small’Telmatherina antoniae from Lake Matano, Indonesia

Genetic divergence, assortative courtship and intermale aggression were assessed between sympatric colour morphs of the sailfin silverside Telmatherina antoniae, endemic to Lake Matano, Indonesia. Genetic analysis using microsatellite markers showed no barriers to gene flow among T. antoniae primary colour morphs (blue and yellow) within sampling sites, sympatric populations or at the lake-wide level. Low but significant genetic differentiation was found between yellow morphs and mixed (blue-yellow) morphs. Behavioural surveys indicated assortative courtship does occur along primary colour lines; however, intermale aggression among paired and intruding male morphs appeared equal with respect to male colour. These observations support the hypothesis that males view other males as threats to their courtship regardless of their colour. This study supports recent work suggesting that assortative mating is present in T. antoniae despite a lack of reproductive isolation among colour morphs.