Ontogenetic Color Change Research Articles

Erythrodiplax ana sp. nov. (Odonata: Libellulidae) from Brazilian palm swamps.

Erythrodiplax ana sp. nov. (male holotype, six male and three female paratypes), collected in Vereda wetlands (a unique Neotropical savanna environment) in Uberlândia (Minas Gerais) and Chapada dos Guimarães (Mato Grosso), Brazil, is described and illustrated. The new species fits in Borror's Basalis Group, and can be distinguished from other species by the combination of the following traits: blue pruinosity dorsally on thorax and third to eighth abdominal segments; sides of the thorax olive-green; face ivory or olive-green; wings hyaline with a small apical brown spot on all four wings, well defined in females; male genitalia with sclerotized erectile posterior lobe and inflatable sac-like median process. Last instar larvae were reared in the laboratory, resulting in the description of the larva. We also followed this population for 13 months and present resulting biological notes and comments on ontogenetic color change in males, as well as longevity.

Ontogenetic shifts in risk behaviours are related to body size and coloration in spiny-footed lizards

Ontogenetic colour changes in animals generally involve cryptic juveniles developing conspicuous coloration when they achieve sexual maturity. However, there are several species in which juveniles develop conspicuously coloured tails that become cryptic in adults. In lizards, colourful tails may act as an antipredator mechanism, either by diverting predator attacks from vital body parts to the expendable tail (decoy hypothesis) or, when associated with tail movements, by signalling to the potential predator that it has been spotted and an attack will probably not succeed (pursuit deterrent hypothesis). In both cases, the antipredator function would allow lizards with colourful tails to show more risk-taking behaviours. The aim of this study was to test whether conspicuous coloration was related to risk behaviours in spiny-footed lizards, Acanthodactylus erythrurus, a species with red-tailed juveniles. Behaviour was recorded in free-ranging lizards and several risk-related behavioural indices were calculated. As predicted, risk behaviour and tail coloration were found to be related, as redder (less orange) lizards stayed further from refuge, maybe because redder coloration was associated with a perception of lower predation risk. Coloration was not related to any other behavioural index, including tail displays, but the level of activity was negatively related to lizard size, suggesting a change towards less active behaviour associated with growth, probably because energy and thermoregulatory requirements depend on body size. In conclusion, the link between red coloration and risk-taking behaviour in spiny-footed lizards supports the antipredator function of this coloration that enables more colourful lizards to take more risks when necessary. Moreover, the nonsignificant association between coloration and tail displays is not consistent with the pursuit deterrent hypothesis, thus making the decoy hypothesis more probable.

A colourful youth: ontogenetic colour change is habitat specific in the invasive Nile perch

External body colour is an important trait contributing to phenotypic diversity and individual fitness in fish species. In this study, we use a combination of experimental techniques and field observations to examine patterns of colour divergence in the introduced Nile perch population of Lake Nabugabo, Uganda. We aim to determine whether the proportion of black–brown body colouration of Nile perch differs over a number of size classes, across ecologically distinct wetland edge and forest edge habitats, and whether these differences are the result of rapid (physiological) or ontogenetic (morphological) colour change. We found substantial colour differences in Nile perch between habitats, but trends were not consistent across size classes. Small Nile perch ( 40 cm SL) Nile perch. Inter-habitat differences in colour in the small size class, and shifts in colour from juvenile to adult appear to be the result of morphological colour change associated with distinct ontogenetic shifts in resource use.

From deception to frankness: Benefits of ontogenetic shift in the anti-predator strategy of alder moth Acronicta alni larvae

Abstract Animals can avoid prédation by masquerading as objects that are not food to their predators. Alder moth Acronicta alni larvae go through an impressive ontogenetic change from masquerade to highly conspicuous appearance: early larval stages resemble bird droppings but in the last instar the larval coloration changes into striking yellow-and-black stripes. We hypothesized that such a change may be driven by differential prédation favoring dissimilar anti-predator strategies in different life stages. We show with a series of laboratory assays that larvae are distasteful to birds regardless of their developmental stage, suggesting that ontogenetic color change is not driven by the differential chemical defense. Birds showed higher variance in hesitation toward conspicuous prey; some individuals hesitated long time before attacking whereas all birds attacked instantly masqueraded prey. We also found that the activity level of the larvae increased with age, which fits to the fact that larvae need to move from foliage to pupation sites. In the field by using artificial larvae resembling the two life-history stages we found prédation risk to vary during the season: In early summer larger yellow-and-black larvae were attacked most, whereas later in the summer small ‘bird-dropping-larvae’ suffered the highest prédation. We conclude that the ontogenetic switch from masquerading to aposema-tism is adaptive most likely because actively moving prey cannot mimic immotile objects and thus, aposematism during the active and vulnerable period when larvae are searching for pupation sites becomes beneficial.

Taxonomic review of the tree frog genus Rhacophorus from the Western Ghats, India (Anura: Rhacophoridae), with description of ontogenetic colour changes and reproductive behavior.

A taxonomic revision of the Western Ghats species from the genus Rhacophorus is presented. Based on museum studies and new collections from localities spanning the known range of Western Ghats Rhacophorus, we review the four known species of this genus, their type specimens, current taxonomic status and their geographic distribution on the basis of morphological and molecular data. The holotypes of Rhacophorus calcadensis, R. lateralis and R. nialabaricus are redescribed. The previously unidentified holotype of Rhacophorus inalabaricus is herein fixed. Descriptions of ontogenetic colour change (OCC) in the Western Ghats Rhacophorus are provided and we conjecture the taxonomic utility of OCC. Additionally we provide observations on nesting behaviour of each species, and report multiple male participation during amplexus, oviposition and foam nest construction in R. lateralis and R. malabaricus.

Transcriptomics of morphological color change in polychromatic Midas cichlids

BackgroundAnimal pigmentation has received much attention in evolutionary biology research due to its strong implications for adaptation and speciation. However, apart from a few cases the genetic changes associated with these evolutionary processes remain largely unknown. The Midas cichlid fish from Central America are an ideal model system for investigating pigmentation traits that may also play a role in speciation. Most Midas cichlids maintain their melanophores and exhibit a grayish (normal) color pattern throughout their lives. A minority of individuals, however, undergo color change and exhibit a distinctive gold or even white coloration in adulthood. The ontogenetic color change in the Midas cichlids may also shed light on the molecular mechanisms underlying pigmentation disorders in humans.ResultsHere we use next-generation sequencing (Illumina) RNAseq analyses to compare skin transcriptome-wide expression levels in three distinct stages of color transformation in Midas cichlids. cDNA libraries of scale tissue, for six biological replicates of each group, were generated and sequenced using Illumina technology. Using a combination of three differential expression (DE) analyses we identified 46 candidate genes that showed DE between the color morphs. We find evidence for two key DE patterns: a) genes involved in melanosomal pathways are up-regulated in normally pigmented fish; and b) immediate early and inflammatory response genes were up-regulated in transitional fish, a response that parallels some human skin disorders such as melanoma formation and psoriasis. One of the DE genes segregates with the gold phenotype in a genetic cross and might be associated with incipient speciation in this highly “species-rich” lineage of cichlids.ConclusionsUsing transcriptomic analyses we successfully identified key expression differences between different color morphs of Midas cichlid fish. These differentially expressed genes have important implications for our understanding of the molecular mechanisms underlying speciation in this lineage of extremely young species since they mate strongly assortatively, and new species may arise by sexual selection due to this color polymorphism. Some of the human orthologues of the genes identified here may also be involved in pigmentation differences and diseases and therefore provide genetic markers for the detection of human pigmentation disorders.

Acrossocheilus longipinnis (Wu 1939), a senior synonym of Acrossocheilus stenotaeniatus Chu & Cui 1989 from the Pearl River basin (Teleostei: Cyprinidae)

A detailed morphological comparison of the currently recognized subspecies, Acrossocheilus iridescens longipinnis andA. i. iridescens, shows that there are differences in body coloration of juveniles and some osteological characters, inaddition to the structure of the first branched dorsal-fin ray and the shape of the distal edge of the dorsal fin which arecurrently used to distinguish them. These differences support the taxonomic elevation of the two subspecies to species.Based on examination of the type specimens of Acrossocheilus stenotaeniatus, and comparison with A. longipinnis, it isconcluded that A. longipinnis is a senior synonym of A. stenotaeniatus. Acrossocheilus longipinnis is redescribed. Thecurrent generic classification of the two species is discussed based on the body coloration of juveniles and ontogenetic color change.

Behavioral and ontogenetic colour changes of a poorly known lutjanid

Despite its high economic value to fisheries, little is known about the ecology of the recently described Lutjanus alexandrei. This is the first report on the array of colouration exhibited by this species in its natural habitats: coral reefs, algal beds and mangroves. Five colour patterns occur in L. alexandrei, and they are related to different life phases or behaviour. Variable colouration is shown on the head, body and fin edges. Colour patterns range from uniform to barred and blotched, from white to red and brown. This variable colouration is mostly related to camouflage on different backgrounds. Some of these patterns are also displayed during interspecific associations. Further investigations are necessary to expand our knowledge on the ecology of this recently described species.

Ontogenetic colour change in females as a function of antiharassment strategy

Mate choice by females is an important component of sexual selection in many species. Theoretically, female sexual traits may be influenced by selection acting on the females via male mate choice, while the evolutionary consequences of male mate preferences are largely unknown, especially in the context of sexual conflict. We tested whether male mate choice affects the evolution of female colour in the damselfly Ischnura senegalensis in which females exhibit dimorphism consisting of a gynomorph that experiences ontogenetic colour change and an andromorph that does not. We first quantitatively confirmed that only gynomorphs change their body colour in relation to sexual maturation. In field experiments, males were unwilling to mate with sexually immature gynomorphs, although they attempted to mate with immature andromorphs. This is because males changed their mating preference for female colour depending on previous copulation experiences with sexually mature females. As a result, immature andromorphs received more male harassment than sexually immature gynomorphs, and then showed decreased food intake. Immature-specific colour functioned to avoid costly male harassment during female prereproductive stages, suggesting that ontogenetic colour changes in females have evolved as an antiharassment strategy of females via male mate choice. ► Female damselfly experienced ontogenetic colour change. ► Females with immature-specific colour efficiently avoided male harassment. ► Avoiding harassment increased food intake in females. ► Male choice may lead to the evolution of antiharassment strategy in females.

Morphological, molecular, and in situ behavioral observations of the rare deep-sea anglerfish Chaunacops coloratus ( ), order Lophiiformes, in the eastern North Pacific

In situ observations and collections of Chaunacops coloratus (Garman, 1899) from seamounts in the eastern North Pacific Ocean lend new behavioral, morphological and molecular data to an under-sampled, deep-sea group of fishes in the order Lophiiformes. Seven observations were made at Davidson Seamount, 130km southwest of Monterey, CA, and from the Taney Seamount chain, 290km west of Moss Landing, CA, from depths ranging from 2313 to 3297m. Specimens were collected at both locations. Morphometric and meristic analyses were performed to identify individuals to the species level. These observations of C. coloratus provide greater latitude and depth distributions in the eastern North Pacific Ocean than previously known. Detailed habitat information indicated the fish occurred near manganese-encrusted volcanic talus slopes, a highly rugose habitat. Video observations revealed possible ontogenetic color changes in which small fish were blue and large fish were red. Video recorded rapid, vertical swimming as an escape response and maneuvering, or walking, with pectoral and pelvic fins and esca deployment. Phylogenetic analyses used here verify what has been known since Garman first described C. coloratus in 1899, that Chaunax and Chaunacops are closely related; molecular tools complement previous knowledge and genetic information created has been submitted to GenBank for further use by the scientific community.

Male mate choice based on ontogenetic colour changes of females in the damselfly Ischnura senegalensis

While male mate choice behaviour has been reported in many taxa, little is known about its plasticity and evolutionary consequences. In the damselfly Ischnura senegalensis, females exhibit colour dimorphism (gynomorph and andromorph). The body colour of gynomorphs changed ontogenetically in accordance with sexual maturation, while little change occurred in andromorphs. To test the male mate choice between sexually immature and mature females of both morphs, binary choice experiments were conducted. Virgin males that were reared separately from females after emergence did not show significant preference between sexually immature and mature females for both morphs, indicating that virgin males were unable to discriminate female reproductive status. On the other hand, males that had experienced copulation with gynomorphs preferred sexually mature gynomorphs to sexually immature ones. However, males that had experienced copulation with andromorphs could not discriminate between sexually immature and mature andromorphs, probably due to the absence of significant ontogenetic change in their thoracic colour. Therefore, female body colour is an important cue for males in discriminating between sexual maturation stages. Learned mate discrimination depending on copulation experience might help males to detect potential mates effectively and avoid sexually unreceptive immature female. We finally discuss the adaptive significance of the ontogenetic colour change in females.

Ontogenetic Color Change in the Firemouth Cichlid, Thorichthys meeki

Color pattern changes in fishes can vary from nearly instantaneous changes to long term, developmental (ontogenetic) changes. Species-typical patterns of ontogenetic color change (OCC) can provide insight regarding the behavior, ecology, and evolution of a taxon. Observations performed on laboratory-reared Firemouth Cichlids, Thorichthys meeki, from hatching to age 205 days, revealed 16 dynamic color pattern elements. Color pattern changes were correlated with age, but a significantly better correlation was found with body size. Ontogenetic color change in the Firemouth Cichlid featured the expression of some transitory color pattern elements not found in adults, and several elements and their sequence of expression were similar to those previously described for other cichlid species.

Ontogenetic colour changes in an insular tree species: signalling to extinct browsing birds?

* Animals often use colours to hide from predators (crypsis) or advertise defences (aposematism), but there is little evidence for colour-based defence in plants. * Here, we test whether ontogenetic changes in leaf colour of lancewood (Pseudopanax crassifolius) may have been part of a defensive strategy against flightless browsing birds called moa, which were once the only large herbivores in New Zealand. We tested this hypothesis by conducting spectrographic measurements on different-sized plants grown in a common garden. We also compared these results with observations on a closely related, derived species that evolved in the absence of moa on the Chatham Islands. * Spectrographic analyses showed that birds would have difficulty distinguishing seedling leaves against a background of leaf litter. Conversely, brightly coloured tissues flanking spines on sapling leaves are highly conspicuous to birds. Once above the reach of the tallest known moa, adults produce leaves that are typical in appearance to adult leaves. The Chatham Island species lacks ontogenetic colour changes entirely. * Overall, the results indicate that P. crassifolius goes through a remarkable series of colour changes during development, from cryptically coloured seedlings to aposematically coloured saplings, which may have formed a defensive strategy to protect against giant browsing birds.

Ontogenetic colour change and the evolution of aposematism: a case study in panic moth caterpillars

1. Aposematism is a widely used antipredator strategy in which an organism possesses both warning coloration and unprofitable characters. Theoretical evidence suggests that aposematic colour should develop when high opportunity costs imposed by crypsis force an organism to engage in conspicuous behaviours. Hence, it is expected that ontogenetic colour change (OCC) in larval insects should include aposematism when foraging needs compel behavioural modifications that preclude a continued state of crypsis. 2. To test this idea, I first investigated whether OCC in caterpillars of the panic moth Saucrobotys futilalis was indicative of a switch from cryptic to aposematic coloration. I then examined the context of panic moth OCC as it related to foraging patterns and behavioural conspicuousness. 3. Early Saucrobotys instars are a cryptic green, but later instars become progressively more orange and develop black spots. Early instar larvae forage cryptically on the inner parenchyma of silked-together host plant leaves to avoid predation, but are rapidly forced to engage in conspicuous foraging behaviours as they outgrow the resources afforded by their shelters. Both coloration and behaviour reach maximal conspicuousness in final instar larvae. 4. As predicted, OCC encompassed a change from crypsis to aposematism in Saucrobotys. Aposematic function was demonstrated by changes in both antipredator behaviour patterns and effectiveness of predator deterrence in early and late instars. Moreover, increased opportunity costs of crypsis and behavioural conspicuousness coincided with the onset of aposematic coloration. 5. This pattern of OCC suggests that aposematic coloration in Saucrobotys develops as a response to constraints imposed by crypsis. Moreover, my study illustrates the importance of the study of ontogenetic patterns in determining how behaviour, morphology, and predator responses interact to influence the initial evolution of phenomena such as aposematism.

The adaptive significance of ontogenetic colour change in a tropical python.

Ontogenetic colour change is typically associated with changes in size, vulnerability or habitat, but assessment of its functional significance requires quantification of the colour signals from the receivers' perspective. The tropical python, Morelia viridis, is an ideal species to establish the functional significance of ontogenetic colour change. Neonates hatch either yellow or red and both the morphs change to green with age. Here, we show that colour change from red or yellow to green provides camouflage from visually oriented avian predators in the different habitats used by juveniles and adults. This reflects changes in foraging behaviour and vulnerability as individuals mature and provides a rare demonstration of the adaptive value of ontogenetic colour change.

Life‐history traits and ontogenetic colour change in an arboreal tropical python, Morelia viridis

AbstractThe Pythonidae are a widely distributed group of snakes that fill a variety of niches in Africa, Asia and Australasia. We used mark–recapture techniques to describe the life‐history traits and colour change in the green python Morelia viridis, a species that is popular in the captive pet industry but poorly known in the wild. Modelling of growth rates revealed that males and females reach sexual maturity after 2.4 and 3.6 years, respectively, and are predicted to live for at least 15 years. Extrapolation from small individuals revealed a highly seasonal breeding period with hatching in late November. However, few hatchlings were recorded in any one year, suggesting that adults do not breed every year. The adult sex ratio did not differ from parity, but immature females outnumbered immature males. Approximately 50% of all snakes captured were adult sized. Sexual dimorphism was not detected in the adults, but juvenile females have larger heads than males. Ontogenetic colour change (OCC) from yellow to green occurred between 53 and 59 cm and, based on growth rates, occurs at c. 1 year of age. This change took place rapidly without an associated shedding of skin. Green pythons have a slow life history, and populations may be vulnerable to removal of individuals for the captive pet trade. They also provide excellent opportunities for examining the evolutionary significance of OCC.

Blue tail and striped body: why do lizards change their infant costume when growing up?

Ontogenetic changes in color and pattern that are not directly related to reproduction are very common yet remain a poorly understood phenomenon. One example is conspicuous colors in the tails of fish, amphibians, and reptiles that fade out later in life. We suggest a novel hypothesis: conspicuous tail colors that appear only in juveniles compensate for an increased activity level, deflecting imminent attacks to the tail. We observed blue-tailed, newly hatched lizards (Acanthodactylus beershebensis) in the field and compared 5 behavioral parameters with those of older individuals that had already lost their neonate coloration. In addition, we explored whether tail displays, often assumed to direct a predator’s attention to the tail, disappear with the color change. Striped blue-tailed hatchlings foraged more actively than 3-week-old juveniles, spent a longer time in open microhabitats, and performed deflective tail displays. In comparison, 2 other lacertids that do not undergo ontogenetic change did not switch to safer foraging when growing up. The results suggest that activity alteration may be a major factor affecting the ontogenetic color and pattern change. Active lizards that forage in open habitats increase their probability of attack by ambush predators. Conspicuous colors and deflection displays may shift attacks to the expendable tail, increasing the prey’s overall probability of surviving attacks. The persistence of both striped body pattern and blue tail fits the active foraging period of neonates and hence may be appropriate for other species that display a conspicuous tail accompanied by a striped pattern. Key words: Acanthodactylus beershebensis, antipredatory behavior, autotomy, foraging activity, ontogeny. [Behav Ecol]

Correlations between Ontogenetic Change in Color Pattern and Antipredator Behavior in the Racer, Coluber constrictor

AbstractDifferences in snake color pattern have been demonstrated to affect behaviors involved in antipredator defense. Snakes with blotched or banded color patterns are concealed when not moving, and tend to rely on concealment and aggression for defense. In contrast, snakes with uniform or striped color patterns are easily seen when stationary, but their speed and direction are difficult to track when moving. They tend to rely on flight for protection. Some snake taxa exhibit ontogenetic change in color pattern, but the behavioral consequences of this change have not been investigated. I present results of a behavioral study in the racer, Coluber constrictor, which has a blotched juvenile color pattern but is uniformly colored as an adult. Hatchling racers were significantly more likely than adults to show aggressive behavior when confronted with a model predator, whereas adults were more likely to flee. This supports the hypothesis that changes in behavior and color pattern are correlated in this species to provide effective antipredator defense at different stages of life history. I also examined sprint speed, which may be an important factor in antipredator defense. Juvenile and adult racers showed a similar relationship between length and speed, a pattern also seen in other species that lack color change. This result suggests that sprint speed is not a causal factor in the evolution of ontogenetic color change.

Molecular evolution of the chalcone synthase gene family and identification of the expressed copy in flower petal tissue of Viola cornuta

Chalcone synthase (CHS), the first committed enzyme in the flavonoid biosynthetic pathway, is commonly encoded by multi-gene families with select members of these families accounting for the majority of expression. We have examined the CHS gene family in Viola cornuta, a plant whose flowers undergo ontogenetic color change. Using both RNA and RNA/DNA samples isolated from floral tissues at different pigment stages, we obtained 14 unique sequences from 60 total clones of a 288 bp fragment from the catalytic region of CHS. The V. cornuta sequences were monophyletic when compared to CHS orthologs from other taxa. Substitution models generally indicated unequal rates of transition and transversion as well as significant rate variation among sites. With a Tamura-Nei correction, nucleotide divergence ranged from 0.3 to 10.6% with the vast majority as synonymous changes. The nucleotide divergence pattern suggests designation of three V. cornuta CHS clades; based on divergence of CHS orthologs, these clades are consistent with three CHS orthologs in V. cornuta. Sequences from only a single clade were found to be expressed in all three floral pigment stages.

Coat colour variation in the banded palm civet Hemigalus derbyanus and in Owston's civet Chrotogale owstoni

ABSTRACT 1. Coat colour variation was studied in two viverrid species belonging to the subfamily Hemigalinae, on the basis of museum specimens and observations of live animals. 2. In both species, polymorphism and ontogenetic colour change occur, and in the Owston's civet, sexual dimorphism in coat colour was identified.