Dorsal Coloration Research Articles

A new species of the genus Scincella (Squamata: Scincidae) from Mount Fansipan, Hoang Lien Son Range, northwestern Vietnam

We describe a new species of the genus Scincella Mittleman, 1950 from northwestern Vietnam, based on a new collection of ground skinks from Mount Fansipan of the Hoang Lien Son Range in Lao Cai Province. Scincella fansipanensis sp. nov. is distinguished from other Scincella species in the Indochina region and southern China by body size (SVL), separation of prefrontals, number of midbody scale rows, paravertebral scale rows, nuchals and subdigital lamellae on toe IV, separation of toe from finger when limbs are adpressed along the body, and dorsal color pattern. The new species is further distinguished from its congeners by uncorrected genetic distances of 14.60–21.41% (COI gene). The new species is currently known only from high elevation areas of Mt. Fansipan in Vietnam.

Altitude and ground brightness explain interpopulation variation in dorsal coloration in a lizard

Abstract Non-signaling functions of coloration include thermoregulation (thermal melanism hypothesis), protection against ultraviolet radiation (photoprotection hypothesis), and concealment from predators (crypsis hypothesis). We investigated whether dorsal coloration in 19 populations of spiny-footed lizards, Acanthodactylus erythrurus, across the Iberian Peninsula varies according to these functions. We captured adult males and females in each population and calculated standardized dorsum brightness estimates from photographs. We also calculated standardized ground luminosity estimates and gathered information on latitude, altitude, mean annual temperature, and mean annual solar radiation for each location. Males showed a higher percentage of black coloration and a more contrasted dorsum than females, suggesting different selection pressures on dorsal coloration in both sexes. Furthermore, males showed a darker dorsum and a higher percentage of black coloration at higher altitudes and when the ground was darker. In contrast, females exhibited a darker dorsum only when the ground was darker and a higher percentage of black coloration only at higher altitudes. We also observed that the variation of dorsum luminosity within males and the variation of dorsum luminosity among females within populations were both positively related to the variation of ground luminosity among different points within locations. Latitude, temperature, and solar radiation were not significantly related to dorsal coloration in either sex. Our results support the photoprotection and crypsis hypotheses in males and, to some extent, in females, whereas the thermal melanism hypothesis is weakly supported in both sexes. These findings suggest that there is local adaptation in the dorsal coloration of the spiny-footed lizard.

The nomenclatural status of “Anoplophallus maculatus” Cope, 1895, its consequences on the systematics of Lycodon subcinctus auctorum, and the description of a new species (Squamata: Colubridae)

The Malayan banded wolf snake, Lycodon subcinctus (F. Boie, 1827) has a complicated taxonomic and nomenclatural history. For almost a century, the combination Anoplophallus maculatus Cope, 1895 has been applied to populations of L. subcinctus from southern China, with various authors recognizing the taxon maculatus as a subspecies (i.e., Lycodon subcinctus maculatus) or junior synonym. A recent study that proposed the elevation of Chinese L. subcinctus to species rank (as Lycodon “maculatus”) prompted us to re-investigate several nomenclatural issues relevant to Anoplophallus maculatus that have not been fully addressed in the literature. We show that Anoplophallus maculatus was not described as a new species, and actually refers to Megalops maculatus Hallowell, 1861, a Neotropical snake currently known as Leptodeira maculata (Dipsadinae). As a consequence, populations of L. subcinctus recently recognized as Lycodon “maculatus”, have no valid binomen applied to them. To resolve this issue, we provide a new species name for populations of L. subcinctus from China and include a morphological description based on specimens collected across all of mainland Southeast Asia. The new species, Lycodon neomaculatus sp. nov., occurs well outside of southern China, and inhabits Indochina (Cambodia, Laos, Thailand, Vietnam) and eastern Myanmar. Lycodon neomaculatus sp. nov. is distinguished from both L. sealei and L. subcinctus by subtle differences in adult dorsal color pattern and body scalation. The distributions of L. neomaculatus sp. nov. and L. subcinctus sensu stricto appear to be allopatric, and the Isthmus of Kra region in peninsular Thailand may act as a biogeographic filter separating the two species.

Detectability of a poison frog and its Batesian mimic depends on body posture and viewing angle.

Aposematic signals warn predators that prey should be avoided due to dangerous secondary defences. However, as warning signals do not always produce avoidance, warning colors may evolve as a trade-off balancing detectability against signal saliency. For Batesian mimics, which display salient signals but lack secondary defenses, the costs of predator encounters are greater, potentially increasing the benefit of crypsis. This raises the question of whether imperfect mimicry may reduce detectability while retaining mimetic efficacy. We tested this hypothesis with the poisonous frog Ameerega bilinguis and undefended Batesian mimic Allobates zaparo, using computational visual modeling and screen-based detection trials with human participants. We found that both species incorporate camouflage into their warning colors, but to different degrees depending on viewing angle and behavior. Contrary to expectation, we found differences in detectability between model and mimic that do not adhere to the hypothesized cryptic mimetic phenotype. To aerial observers, we found the mimic to be more detectable than the model. To terrestrial observers, likely owing to the model's bright ventral color, we found the model more detectable in viewing angles that highlight the ventral coloration, whereas the mimic was more detectable in viewing angles that highlight the dorsal coloration. Consequently, we suggest that in addition to being the result of perceptual or developmental constraints, imperfect mimicry may also evolve as an adaptive strategy which balances camouflage with different signaling functions. Our findings complement the emerging view that aposematic signals may evolve in response to a multitude of selection pressures beyond aversion alone.

How does finishing duration on lucerne pasture influence the muscle and fat spectro-colorimetric properties and dorsal fat firmness in lambs?

There are a number of differences in the meat and carcass quality traits between pasture-raised and concentrate-raised lambs that may further be used to trace back the diet, but the extent to which these differences are modulated by pasture-finishing duration is unknown. In this study, we investigated the changes in longissimus thoracis et lumborum muscle and fat spectrocolorimetric properties, and dorsal fat firmness, in lambs switched from a stall-fed concentrate-based diet to grazing on lucerne for various durations (0, 21, 42, 63 days) pre-slaughter. Stall-fed lambs from the different treatment groups were managed in a single group and lucerne pasture-finished lambs from the different treatment groups also co-grazed in a single group. The level of concentrate fed to stall-fed lambs was adjusted to maintain a similar mean pattern of growth between lucerne pasture-fed and stall-fed lambs. The trial used a total of 141 lambs over two successive years. Dorsal fat was firmer in lambs finished on lucerne pasture, even for the shortest finishing duration (21 days), the difference being of commercial importance. Dorsal fat colour and carotenoid content showed changes at 21 days on lucerne pasture but did not change further for longer lucerne pasture-finishing durations. In contrast, perirenal fat lightness, yellowness, chroma and carotenoid content showed changes at 21 days on lucerne pasture and increased consistently with lucerne pasture-finishing duration. Although these changes in fat spectrocolorimetric properties were not, or barely, visible to the naked eye, they could be of interest for authenticating the duration of lucerne pasture-finishing. Muscle redness increased consistently with the duration of lucerne pasture-finishing, the change becoming significant from 42 days on lucerne pasture and being visible to the naked eye. We observed a consistent decrease of muscle hue angle and perirenal fat redness and a consistent increase in perirenal fat hue angle with lucerne pasture-finishing duration, but these changes only became significant from 63 days on lucerne pasture. The pattern of change in the lamb carcass and meat quality traits measured according to lucerne pasture-finishing duration therefore varied between the tissues and quality traits.

Citizen science and color pattern analysis indicate unreported Batesian mimicry between Neotropical snakes

AbstractBatesian mimics decrease their chance of predation by their resemblance to different, dangerous or unpalatable species but this relationship is often inferred without quantitative approaches. Snakes are notorious Batesian mimics, especially the Neotropical genus Xenodon, which comprises species that are putative mimics of venomous snakes such as coral snakes (genus Micrurus) and lanceheads (or “fer‐de‐lance,” genus Bothrops). Herein, we propose that Xenodon severus is a batesian mimic of the sympatric and highly venomous Amazonian bushmaster (Lachesis muta), the longest viper in the world, and not of lanceheads (Bothrops spp.). We compiled all available photographs of X. severus from citizen science platforms and published literature to test this mimicry through a quantitative dorsal color pattern analysis between this species and both L. muta and a lancehead Bothrops brazili. We classified georeferenced photographs as potential “mimic” or “non‐mimic” and tested whether “mimics” were found on average closer to L. muta's range centroid than “non‐mimics.” The color pattern analysis showed that X. severus is more similar to L. muta than to B. brazili. Furthermore, “mimics” were significantly closer to the centroid of L. muta. Our results suggest that X. severus is likely a mimic of L. muta and that this relationship may vary across their distribution. Our findings highlight the significant role of citizen science platforms in assessing ecological relationships and the importance of using quantitative methods such as dorsal color pattern analysis to test mimicry.Abstract in Portuguese is available with online material.

BIOLOGICAL ASPECTS OF Ameivula nigrigula (SQUAMATA: TEIIDAE): FEEDING HABIT, SEXUAL DIMORPHISM, REPRODUCTION AND MATURATION OF FEMALES

Life history information plays a crucial role in comprehending the evolutionary processes that shape ecological patterns within species, but there is limited information available on the reproductive and other aspects of tropical Squamata. In this study, we present a comprehensive analysis of dietetic and morphometric data, specifically related to the size and sex determination of Ameivula nigrigula, aiming to investigate if there is sexual dimorphism and identify the onset of sexual maturity in female individuals. By thoroughly examining the stomach contents, we observed that the majority of specimens retain food remnants, with a prevalence of small prey items such as Hymenoptera and Isoptera. Our findings reveal a lack of sexual dimorphism in terms of body size, indicating that males and females possess similar dimensions and proportions. Moreover, our investigations suggest that different color patterns do not correspond to distinct stages of female development, as chromatic variations are observed in both juvenile and ovigerous females. Consequently, dorsal coloration may not serve as a reliable indicator of sexual maturity. The observed chromatic variation is likely a form of polymorphism within the population, lacking the potential to determine life stages. Furthermore, our examination of female fertility reveals the presence of one to two eggs per female, consistent with findings in other Teiidae species.

Finotypic plasticity: Predator-induced plasticity in fin size, darkness and display behaviour in a teleost fish.

Fish fins are remarkable devices of propulsion. Fin morphology is intimately linked to locomotor performance, and hence to behaviours that influence fitness, such as foraging and predator avoidance. This foreshadows a connection between fin morphology and variation in predation risk. Yet, whether prey can adjust fin morphology according to changes in perceived risk within their lifetime (a.k.a. predator-induced plasticity) remains elusive. Here, we quantify the structural size of five focal fins in crucian carp (Carassius carassius) following controlled manipulations to perceived predation risk (presence/absence of pike Esox lucius). We also assess if crucian carp respond to increased predation risk by shifts in dorsal fin colouration, and test for differences in how fish actively use their dorsal fins by quantifying the area of the fin displayed in behavioural trials. We find that crucian carp show phenotypic plasticity with regards to fin size as predator-exposed fish consistently have larger fins. Individuals exposed to perceived predation risk also increased dorsal fin darkness and actively displayed a larger area of the fin to potential predators. Our results thus provide compelling evidence for predator-induced fin enlargement, which should result in enhanced escape swimming performance. Moreover, fin-size plasticity may evolve synergistically with fin colouration and display behaviour, and we suggest that the adaptive value of this synergy is to enhance the silhouette of deep-bodied and hard-to-capture prey to deter gape-limited predators prior to attack. Together, our results provide new perspectives on the role of predation risk in development and evolution of fins.

Description of a Remarkable New Skate Species of Leucoraja Malm, 1877 (Rajiformes, Rajidae) from the Southwestern Indian Ocean: Introducing 3D Modeling as an Innovative Tool for the Visualization of Clasper Characters.

A remarkable new deep-water skate, Leucoraja longirostris n. sp., is described based on eight specimens caught during different expeditions to the southern Madagascar Ridge in the southwestern Indian Ocean. The new species differs from all congeners by its remarkably long and acutely angled snout (horizontal preorbital length 17.2-22.6% TL vs. 8.5-11.9% TL and 4.2-6.1 vs. 1.7-3.5 times orbit length, snout angle 65-85° vs. 90-150°). Furthermore, it is apparently endemic to the Madagascar Ridge, distant from the known distribution areas of all congeners. In addition to L. fullonica and L. pristispina, L. longirostris n. sp. is also the only species with plain dorsal coloration. Furthermore, the new species is the only Leucoraja species with an external clasper component dike and, besides L. wallacei, the only one with four dorsal terminal (dt) cartilages. The shape of the accessory terminal 1 (at1) cartilage with four tips is also unique within the genus. A new approach for the visualization of the clasper characters is introduced based on 3D models of all skeletal and external features. This enables a much easier and much more precise interpretation of every single clasper component, of the entire structure, and, in particular, the relationship between external features and skeletal cartilages. A new English translation of the first diagnosis of Leucoraja is provided, along with a revised generic diagnosis and a key to the species of Leucoraja in the Indian Ocean.

Validation of Traditional Species Identification Techniques for Juvenile Mangrove Crabs (Scylla spp.)

Species identification of mangrove crabs at the juvenile stages is crucial for maximizing production. Traditional knowledge in identifying juvenile mangrove crabs (Scylla spp.) is mainstream although the techniques vary with locations and are yet to be validated for their effectiveness. In this study, widespread traditional techniques for identifying juvenile Scylla were validated by looking for patterns through principal component analysis in dorsal carapace features – including bumps, black spots, coloration, and shape – as determined by CL:ICW. The less prominent bumps on the dorsal carapace and the lower CL:ICW of S. olivacea were seen to have the potential for nationwide adoption to distinguish this least preferred species. The dorsal carapace color varies across species but is inconsistent across regions. The presence of black and white spots, texture features such as depression on the center of the dorsal carapace, and growth rates of the samples were found to have no diagnostic applications for juvenile Scylla. This study confirmed the utility of some traditional techniques to identify juvenile S. olivacea without the aid of a device, but no consistent method to differentiate S. serrata from S. tranquebarica was found. Image analysis data on these validated techniques can be added to the machine learning algorithm of existing species identification tools to increase accuracy.

Transcriptome analysis of sexual dimorphism in dorsal down coloration in goslings

BackgroundIn day-old Hungarian white goose goslings, there is a noticeable difference in dorsal down coloration between males and females, with females having darker dorsal plumage and males having lighter plumage. The ability to autosex day-old goslings based on their dorsal down coloration is important for managing them efficiently and planning their nutrition in the poultry industry. The aim of this study was to determine the biological and genetic factors underlying this difference in dorsal down colorationthrough histological analysis, biochemical assays, transcriptomic profiling, and q‒PCR analysis.ResultsTissue analysis and biochemical assays revealed that compared with males, 17-day-old embryos and day-old goslings of female geese exhibited a greater density of melanin-containing feather follicles and a greater melanin concentration in these follicles during development. Both female and male goslings had lower melanin concentrations in their dorsal skin compared to 17-day-old embryos. Transcriptome analysis identified a set of differentially expressed genes (DEGs) (MC1R, TYR, TYRP1, DCT and MITF) associated with melanogenesis pathways that were downregulated or silenced specifically in the dorsal skin of day-old goslings compared to 17-day-old embryos, affecting melanin synthesis in feather follicles. Additionally, two key genes (MC1R and MITF) associated with feather coloration showed differences between males and females, with females having higher expression levels correlated with increased melanin synthesis and darker plumage.ConclusionThe expression of multiple melanogenesis genes determines melanin synthesis in goose feather follicles. The dorsal down coloration of day-old Hungarian white goose goslings shows sexual dimorphism, likely due to differences in the expression of the MC1R and MITF genes between males and females. These results could help us better understand why male and female goslings exhibit different plumage patterns.

Occurrence of Four Freshwater Stingrays (Chondrichthyes: Potamotrygoninae) in the Uatumã River Basin, Amazon Region: A Field Study

The Amazon region has the largest diversity of freshwater stingrays; however, there are still places where information about this group is scarce. The present work aims to record the occurrence of freshwater stingrays in the Uatumã river basin, Amazonas, Brazil. For this, collections were carried out in three municipalities bathed by the Uatumã River, Presidente Figueiredo, Itapiranga, and São Sebastião do Uatumã. The rays were collected through fishing using a hand net and, after capture, were identified through the pattern of the dorsal and ventral color of the disc, the absence or presence of the labial groove, and the organization of the row of spines on the tail, and were also measured, weighed, and sexed. In total, 69 specimens of Potamotrygonines were captured, 59 of which were from the genus Potamotrygon and ten individuals from the genus Paratrygon. The present study provides preliminary information on the characteristics of freshwater stingray species that may occur in the Uatumã River. Furthermore, new research is necessary to improve the identification of specimens to determine the diversity and elucidate aspects related to the biology of elasmobranchs in the Uatumã River Basin, Brazil.

Environmentally associated colour divergence does not coincide with population structure across Lesser Antillean anoles

Abstract Species distributed across heterogeneous environments may undergo local adaptation, which can be limited by the homogenizing effects of gene flow. Lesser Antillean anoles exhibit dorsal colour variation associated with dramatic shifts in environment across small spatial scales, providing an excellent system for studying the maintenance of local adaptation despite ongoing gene flow. The 1995 Soufriere Hills eruption on Montserrat provides an opportunity to understand how natural disasters may influence the evolution of insular species. Thus, our study had two main objectives. First, we collected genetic, phenotypic, and environmental data to investigate whether environmentally associated dorsal coloration reflects underlying population structure in three species of Lesser Antillean anoles. Second, we examined the short-term evolutionary consequences of volcanism by comparing pre- and posteruption samples of Anolis lividus using multilocus sequence data. We found all three species exhibited genetic isolation-by-distance but not isolation-by-environment. Furthermore, phenotypic differences within each species were not predicted by genetic distances, suggesting gene flow across colour morphs. We confirmed the repopulation of A. lividus in the impacted area and found genetic diversity equivalent to pre-eruption sampling. Our findings contribute to our understanding of local adaptation in spatially small-scale systems and the impact of catastrophic natural disasters on population structure.

Winter-ground microhabitat use by differently coloured phenotypes affects return rate in a long-distance migratory bird

Migratory bird populations are declining globally at alarming rates. Non-breeding site conditions affect breeding populations, but generalising non-breeding habitat conditions over large spatial regions cannot address potential fine-scale differences across landscapes or local populations. Plumage characteristics can mediate the effects of environmental conditions on individual fitness. However, whether different phenotypes use distinctive non-breeding sites, and whether they respond to non-breeding site conditions differently remains largely unknown. Stable isotopes (δ13C, δ15N, δ2H) of inert tissues are useful to infer habitat characteristics and geographic origins where those tissues were grown. We collected winter-grown feathers from pied flycatchers (Ficedula hypoleuca) on their breeding grounds over several years from males whose dorsal plumage colouration ranged continuously from brown to black and assessed their stable isotope values as proxies of local habitat conditions. Based on feather δ2H profiles we found that browner males spent their non-breeding season in drier habitats than black males. Assignment to origin analysis shows potential regional non-breeding ground separation between differently coloured males. High within-individual repeatability of both δ13C and δ15N indicate the pied flycatcher males return yearly to similar areas. Blacker males were more likely to return to the breeding grounds after dry years compared with brown males. The opposite was found in wet years. Our study demonstrates that different phenotypes are exposed to different non-breeding site conditions which can differentially affect individual survivorship. This has important ramifications for population dynamics under predicted climate change scenarios where especially brown phenotype pied flycatcher males may be under a risk of decreasing.

The quantitative genetic basis of variation in sexual versus non-sexual butterfly wing colouration: autosomal, Z-linked, and maternal effects.

Viability indicator traits are expected to be integrated extensively across the genome yet sex-limited to ensure that any benefits are sexually concordant. Understanding how such expectations are accommodated requires elucidating the quantitative genetic architecture of candidate traits in and across the sexes. Here we applied an animal modelling approach to partition the autosomal, allosomal, and direct maternal bases of variation in sexual versus non-sexual dorsal wing colouration in the butterfly Eurema hecabe. The sexual colour trait-coherently scattered ultraviolet that is under strong directional selection due to female choice-is brighter and more expansive in males, and overlays non-sexual pigmentary yellow markings that otherwise dominate both wing surfaces in each sex. Our modelling estimated high and sexually equivalent autosomal variances for ultraviolet reflectance (furnishing h2 ~ 0.58 overall and ~0.75 in males), accompanied by smaller but generally significant Z-linked and maternal components. By contrast, variation in non-sexual yellow was largely attributed to Z-linked sources. Intersexual genetic correlations based upon the major source of variation in each trait were high and not different from 1.0, implying regulation by a pool of genes common to each sex. An expansive autosomal basis for ultraviolet is consistent with its hypothesized role as a genome-wide viability indicator and ensures that both sons and daughters will inherit their father's attractiveness.

Eastern Black Kingsnake Lampropeltis nigra dorsal scale colouration primarily adapted for thermoregulation

The Eastern Black Kingsnake Lampropeltis nigra exhibits variation in colouration and pattern throughout its range. Drivers behind this colour variation remain largely unknown. To elucidate patterns in the percentage of light pigmentation in L. nigra dorsal scales (% light) we compared two primary hypotheses. Our first hypothesis posited that L. nigra colouration has been adapted for thermoregulation (thermoregulation). Alternatively, we hypothesised that L. nigra colouration has been adapted to avoid detection by predators and prey (crypsis). To test our hypotheses, we modeled L. nigra % light from 46 counties within Mississippi as a function of average temperature, average maximum temperature (thermoregulation) and soil value (darkness of soil colour; crypsis). We included percentage forest cover as a modifying variable in the thermoregulation hypothesis and an interacting variable in the crypsis hypothesis. The best competing model included average temperature and percent forest cover as explanatory variables (LOOIC = -291.3, weight = 0.84, Bayesian R2 = 0.37 [fixed] and 0.55 [total]). There was a positive relationship between % light and average temperature (β = 0.23, 95% CIs = 0.13, 0.34) and average maximum temperature (β = 0.11, 95% CIs = -0.00, 0.21), and a negative relationship with percent forest cover (β = -0.14, 95% CIs = -0.23, -0.04). These results support the thermoregulation hypothesis. The climate in Mississippi, as in most of the world, is expected to experience shifts over the next century. If ambient temperatures experienced through these changes are outside of L. nigra’s thermal optima, as based on colour patterns and relationships observed in our study, then behavioural adaptations may result in some individuals experiencing thermal advantages that influence this species’ distribution. The patterns observed in our study, and expected changes in L. nigra behaviour and distribution, are likely to occur among other ectothermic species with relatively static colouration. Keywords: Colour adaptation, homeostasis, Mississippi

Effects of Different Astaxanthin Sources on Fillet Coloration and Energy Deposition in Rainbow Trout (Oncorhynchus mykiss)

A 9-week feeding trial was conducted to investigate the effects of different dietary sources of astaxanthin on fillet coloration, texture, and nutrient composition in rainbow trout (Oncorhynchus mykiss). Eight diets were formulated to contain 0, 25, 50, 75, 100, and 125 mg/kg astaxanthin from wall-broken Haematococcus pluvialis (WBHPA), 100 mg/kg astaxanthin from wall-unbroken H. pluvialis (WUHPA), or chemically synthesized astaxanthin (CSA). Each diet was fed to triplicate groups of rainbow trout (mean initial weight of 561 g) twice daily (07:00 and 17:00) to apparent satiation for 9 weeks. Results showed that at the 100 mg/kg astaxanthin inclusion level, the CAS group had higher fillet gross energy, dorsal fillet redness, and dorsal fillet color card score compared to the WBHPA-100 group, with both being higher than the WUHPA group (P<0.05). Fillet astaxanthin content, dorsal fillet yellowness, and lateral line redness and yellowness did not differ significantly between the CSA and WBHPA-100 groups (P>0.05), but were higher than the WUHPA group. When WBHPA was used, the inclusion of 50–100 mg/kg decreased fillet lightness but increased fillet redness, while better fillet texture was served at 75–125 mg/kg. Dietary 25–125 mg/kg WBHPA inclusion increased fillet astaxanthin and gross energy concentrations, with minor effects on fatty acid compositions of fillet. Inclusion of over 100 mg/kg astaxanthin regardless of source decreased fillet threonine and serine contents, and the WBHPA-100 group had lower fillet glycine and alanine contents compared to the control group (P<0.05). In conclusion, CSA had the most significant impact on fillet coloration and energy deposition in rainbow trout, while WUHPA had the least favorable effect. Additionally, the wall-breaking treatment of H. pluvialis can improve the effect of astaxanthin on fillet coloration and nutrient composition in rainbow trout, with a recommended dose range of 75–100 mg/kg.

Convergent and environmentally associated chromatic polymorphism in Bryconops Kner, 1858 (Ostariophysi: Characiformes: Iguanodectidae).

Bryconops Kner, 1858, includes two well defined subgenera based on morphological evidence, with each containing at least one species (B. (Bryconops) caudomaculatus and B. (Creatochanes) melanurus) with a very wide distribution, within which regional populations present color variations. To test if phenotypic variation is related to cladogenetic events, we performed tests for phylogenetic independence and determined the strength of convergence for color characters in relation to water type, as the variation between clear, black and white waters is considered to be one of the major driving forces in the evolution of Amazonian fishes. Color characters for fins above the median line of the body were generally found to be independent from phylogeny and the Wheatsheaf test strongly supports convergence of the dorsal fin color between populations of species in the same type of water, with a similar trend suggested for the color of the dorsal lobe of the caudal fin. This means that simple color characters cannot necessarily be relied upon for taxonomic revisions of the genus as local phenotypic variants may represent environmentally determined plasticity or convergent evolution. Further studies are required to determine the validity of these characters.

Molossusmelini Montani et al. 2021 (Chiroptera, Molossidae) in Brazil: new insights for distribuition, morphology and genetics.

The species M.melini has been observed in both the Pampa and Spinal ecoregions of Argentina. Researchers have underscored that distinguishing M.melini from other species within the same genus relies primarily on craniometric and molecular analyses. Morphological measurements alone do not offer a clear differentiation between M.melini and other members of this genus.This study aims to document the presence of M.melini within the Brazilian ecoregion, focusing on its morphological, morphometric and genetic characteristics. By undertaking a comprehensive examination, we seek to contribute valuable insights into the distribution and differentiation of M.melini in this region. Molossusmelini specimens exhibited a forearm length ranging from 39.9 to 40.08 mm. The average intraspecific divergence was 1.2%, with specimens from the Argentine Pampas clustering in the same clade with a 98% bootstrap support and a posterior probability of: Regarding dorsal colouration, the specimens displayed fur with two bands-a Snow White base colour and apex colours ranging from Olive Brown, Broccoli Brown, Wood Brown to Yellowish-Brown. This marks the first record of M.melini in Brazil, expanding its distribution 1,300 km northeastwards into the Curitiba, Paraná, Atlantic Forest Ecoregion. The findings contribute valuable information on the distribution, morphology, morphometrics and genetics of this species.

Dorsal and Ventral Plumage Coloration Evolve as Distinct Modules with Different Environmental Correlations.

AbstractMany animals exhibit contrast between their dorsal coloration and their ventral coloration. If selection acts differently on dorsal versus ventral coloration, ancestral covariance between these traits should break down, eventually leading to independent modules of trait evolution. Here, we compare the evolution of feather color across body regions for a clade of Australasian songbirds (Meliphagoidea). We find evidence for three modules of covarying color regions. Among these modules, ventral feathers evolve with high lability, evolving at three times the rate of dorsal plumage and 20 times the rate of flight feathers. While both dorsal plumage and ventral plumage are darker in areas with more precipitation and vegetation, we find that dorsal plumage is twice as similar to colors in satellite photos of background substrates. Overall, differential selection on ventral and dorsal colors likely maintains these as distinct modules over evolutionary timescales-a novel explanation for dorsoventral contrast in pigmentation.