Male Coloration Research Articles

ALOG/LSHs, a novel class of transcription factors: Evolutionarily conserved regulators of plant growth and development.

The ALOG/LSH group of proteins is highly conserved across plant lineage, starting from moss to higher flowering plants, suggesting their crucial role in the evolution and adaptation of land plants. The role of ALOG proteins is highly conserved in various developmental responses, such as vegetative and reproductive developmental programs. Their role in meristem identity, cotyledon development, seedling photomorphogenesis and leaf and shoot development has been relatively well established. Moreover, several key pieces of evidence suggest their role in inflorescence architecture and flower development, including male and female reproductive organs and flower colouration. Recent research has started to explore their role in stress response. Functionally, ALOG proteins have been demonstrated to act as transcriptional regulators and are considered a newly emerging class of transcription factors in plants that regulate diverse developmental and physiological processes. This review aims to stimulate discussion about their role in plant development and their role as transcription factors. It also aims to further unravel the underlying molecular mechanism by which they regulate growth and development throughout the plant lineage.

Influence of geographic isolation and the environment on gene flow among phenotypically diverse lizards.

Lizards in the genus Anolis comprise hundreds of species that display a wide range of phenotypic variation closely related to their environment. One example is the Guadeloupean anole (Anolis marmoratus ssp.) that display extreme phenotypic variation, primarily in adult male color and pattern, with twelve described subspecies on the archipelago. Here we examine the relationship between phenotypic and genetic divergence among five subspecies on the two main islands and test the role of geographic isolation and the environment in reducing gene flow. We also examined two offshore island populations to assess the impact of complete geographic isolation on gene flow. We analyzed color phenotypes by measuring spectral reflectance and genomic diversity using SNPs. Genetic divergence was correlated with dorsolateral head and body color phenotypes, and slope and geographic distance were nearly equivalent at explaining this divergence. There was minimal genome-wide divergence at neutral loci among phenotypically disparate subspecies on the two main islands and their differentiation is consistent with a model of divergence with gene flow. Our spatial visualization of gene flow showed an impact of environmental features consistent with a hypothesis of ecologically driven divergence. Nonetheless, subspecies on the two main islands remain interconnected by substantial gene flow and their phenotypic variation is likely maintained at selection-gene flow equilibrium by divergent selection at loci associated with their color phenotypes. Greater isolation, such as inhabiting a remote island, may be required for reducing gene flow. Our findings highlight the role of the environment, adaptation, and geographic isolation on gene flow.

Sexual selection may support phenotypic plasticity in male coloration of an African cichlid fish.

The expression of sexually selected traits, such as ornaments or body coloration, is often influenced by environmental conditions. While such phenotypic plasticity is often thought to precede evolutionary change, plasticity itself can also be a target of selection. However, the selective forces supporting the evolution and persistence of plasticity in sexual traits are often unclear. Using the cichlid fish Astatotilapia burtoni, we show that variation in the level of mate competition may promote plasticity in body coloration. In this species, males can change between yellow and blue colour. We found that experimentally increased competition over mating territories led to a higher proportion of males expressing the yellow phenotype. The expression of yellow coloration was found to be beneficial because yellow males won more staged dyadic contests and exhibited a lower level of oxidative stress than blue males. However, females were more likely to spawn with blue males in mate choice experiments, suggesting that expression of blue coloration is sexually more attractive. The ability to adjust colour phenotype according to the local competitive environment could therefore promote the persistence of plasticity in coloration.

Female cichlids mate with novel androgen receptor mutant males that lack coloration

A key challenge in animal behavior is disentangling the social stimuli that drive conspecific behaviors. For some species, like teleost fish, putative sexual signaling cues are inextricably linked to others, making it difficult to parse the precise roles distinct signals play in driving conspecific behaviors. In the African cichlid Astatotilapia burtoni, males are either dominant or subordinate, wherein bright coloration, territoriality, and courtship behavior inextricably correlate positively with rank. Here, we leveraged androgen receptor (AR) mutant male A. burtoni that lack dominance-typical coloration but not behavior to isolate the role of male coloration in driving female mating behaviors in this species. We found in independent behavioral assays that females behave aggressively towards AR mutant but not WT males, yet still mated with both types of males. Females showed enhanced activation of esr2b + cells in the hypothalamus when housed with either mutant or WT males and this activation scaled with spawning activities. Therefore, there is not a simple relationship between male coloration and female mating behaviors in A. burtoni, suggesting independent sensory mechanisms converge on hypothalamic esr2b cells to coordinate behavioral output.

Diet color affects female preference for mate color in the guppy Poecilia reticulata

It has been argued that a preexisting sensory bias for food color influences female mate preference for male ornament color. However, the effect of diet color over a short period on female preference for color-polymorphic male ornaments has not yet been investigated. In this study, we examined the effect of diet color on female preference for mate color in the guppy Poecilia reticulata, with color-polymorphic ornaments such as orange and black spots. From an early age, females were reared on a diet with orange and black color, respectively. A dichotomous mate choice experiment using females was conducted between males with large orange spots and males with large black spots. Females fed on an orange-colored diet preferred males with large orange spots, whereas those fed on a black-colored diet preferred males with large black spots. Afterward, the diet color treatment for the females was reversed for seven days. This dietary color alteration resulted in the reversal of female preference for male color. These results suggest that diet color has a great influence on female preference for mate color, even within a short period, and environmental gradients may function to maintain color-polymorphic male ornaments in this species.

Orange ornamentation increases sex-specific conspicuousness of juvenile males to conspecifics and predators

Abstract Many animal species have evolved striking colour patterns that attract the opposite sex and intimidate rivals. Although conspicuous coloration is usually restricted to adults in the context of reproduction, this is not always the case. Juvenile collared lizards (Crotaphytus collaris) are sexually dichromatic, wherein males exhibit ‘dorsolateral bars’ that are bright orange and showy, whereas females are light tan and inconspicuous. Given that adult male collared lizards suffer increased predation because of bright adult coloration, we hypothesized that juvenile males might also be more detectable to predators owing to the conspicuousness of their dorsolateral bars. To test this hypothesis, we measured the reflectance of the dorsolateral bars, non-bar background body regions, and the rocky habitat in which the lizards live. We modelled the vision of our study species and its dominant predators to quantify and compare statistically the contrasts of male and female dorsolateral bars against the natural rock background. We also calculated lizard survivorship over a 4 year study period. We found that male orange bars exhibited significantly higher chromatic contrast, but significantly lower achromatic contrast, than female bars when perceived through all visual models. However, the dorsolateral background colour of juvenile males and females did not differ significantly in chromatic or achromatic contrast from rocks in any visual model. Female lizards survived better than male lizards to the yearling (reproductive) stage. Our findings indicate that juvenile male bars are conspicuous both to conspecifics and to predators and that the bars probably increase predation on juvenile males.

Dynamic dichromatism and effects of high temperatures on male coloration plasticity in an ectotherm model

Dynamic dichromatism and effects of high temperatures on male coloration plasticity in an ectotherm model

Variation in nuptial color in relation to sex, individual quality and mating success in the sex-role reversed Phalaropus fulicarius (Red Phalarope)

Abstract In most bird species, males are more ornamented and compete for females, who contribute more to offspring care. In a minority of species, this pattern is reversed, with more colorful females competing for mates and males taking care of parental duties. In such sex-role reversed species, the links between colorful ornamentation, individual quality and mating success are not well established. Phalaropus fulicarius (Red Phalarope) is a colorful sex-role reversed migratory shorebird with regular social polyandry, in which both sexes show considerable color variation. Here, we describe sex differences in color and quantify associations between color variation and indicators of quality and mating success in both sexes. Using a large sample of photos collected across 3 consecutive years on the Arctic breeding grounds, we scored color variation for 4 body parts (bill, crown, cheek, and breast), and analyzed scores separately and combined into an overall color score. Females were more colorful and larger than males, and individuals could be unambiguously sexed by crown color. Nevertheless, there was substantial variation within sexes and some overlap between males and females in bill, cheek, breast, and overall color scores. Assortative mating by color was only found for the bill. Color variation did not correlate with plasma testosterone levels, except for male cheek color. Females in better body condition had yellower bills and higher overall color scores, while early-arriving birds had higher breast and overall scores. Phalaropus fulicarius that bred locally were heavier than those that did not, but they did not have higher color scores. Female color variation did not predict the probability of local social polyandry nor variation in clutch size, and male coloration did not predict the probability of nest predation. In conclusion, P. fulicarius color variation showed modest correlations with individual quality and was unrelated to variation in local reproductive success.

Parental kinship coefficient but not paternal coloration predicts early offspring growth in lake char

The ‘good genes’ hypotheses of sexual selection predict that females prefer males with strong ornaments because they are in good health and vigor and can afford the costs of the ornaments. A key assumption of this concept is that male health and vigor are useful predictors of genetic quality and hence offspring performance. We tested this prediction in wild-caught lake char (Salvelinus umbla) whose breeding coloration is known to reveal aspects of male health. We first reanalyzed results from sperm competition trials in which embryos of known parenthood had been raised singly in either a stress- or non-stress environment. Paternal coloration did not correlate with any measures of offspring performance. However, offspring growth was reduced with higher kinship coefficients between the parents. To test the robustness of these first observations, we collected a new sample of wild males and females, used their gametes in a full-factorial in vitro breeding experiment, and singly raised about 3000 embryos in either a stress- or non-stress environment (stress induced by microbes). Again, paternal coloration did not predict offspring performance, while offspring growth was reduced with higher kinship between the parents. We conclude that, in lake char, the genetic benefits of mate choice would be strongest if females could recognize and avoid genetically related males, while male breeding colors may be more relevant in intra-sexual selection.

Genetic Basis and Evolutionary Forces of Sexually Dimorphic Color Variation in a Toad-Headed Agamid Lizard.

In the animal kingdom, sexually dimorphic color variation is a widespread phenomenon that significantly influences survival and reproductive success. However, the genetic underpinnings of this variation remain inadequately understood. Our investigation into sexually dimorphic color variation in the desert-dwelling Guinan population of the toad-headed agamid lizard (Phrynocephalus putjatai) utilized a multidisciplinary approach, encompassing phenotypic, ultrastructural, biochemical, genomic analyses, and behavioral experiments. Our findings unveil the association between distinct skin colorations and varying levels of carotenoid and pteridine pigments. The red coloration in males is determined by a genomic region on chromosome 14, housing four pigmentation genes: BCO2 and three 6-pyruvoyltetrahydropterin synthases. A Guinan population-specific nonsynonymous single nucleotide polymorphism in BCO2 is predicted to alter the electrostatic potential within the binding domain of the BCO2-β-carotene complex, influencing their interaction. Additionally, the gene MAP7 on chromosome 2 emerges as a potential contributor to the blue coloration in subadults and adult females. Sex-specific expression patterns point to steroid hormone-associated genes (SULT2B1 and SRD5A2) as potential upstream regulators influencing sexually dimorphic coloration. Visual modeling and field experiments support the potential selective advantages of vibrant coloration in desert environments. This implies that natural selection, potentially coupled with assortative mating, might have played a role in fixing color alleles, contributing to prevalence in the local desert habitat. This study provides novel insights into the genetic basis of carotenoid and pteridine-based color variation, shedding light on the evolution of sexually dimorphic coloration in animals. Moreover, it advances our understanding of the driving forces behind such intricate coloration patterns.

Halichoeres sanchezi n. sp., a new wrasse from the Revillagigedo Archipelago of Mexico, tropical eastern Pacific Ocean (Teleostei: Labridae).

A new labrid fish species, Halichoeres sanchezi n. sp., is described from eight specimens collected in the Revillagigedo Archipelago in the tropical eastern Pacific Ocean, off the coast of Mexico. The new species belongs to the Halichoeres melanotis species complex that is found throughout the region, differing by 2.4% in the mtDNA cytochrome c oxidase I sequence from its nearest relative, H. melanotis from Panama, and 2.9% from Halichoeres salmofasciatus from Cocos Island, off Costa Rica. The complex is distinguished from others in the region by having a black spot on the opercular flap and a prominent black area on the caudal fin of males. The juveniles and initial phase of the new species closely resemble those of H. salmofasciatus and Halichoeres malpelo from Malpelo Island of Colombia, differing in having an oblong black spot with a yellow dorsal margin on the mid-dorsal fin of initial-phase adults as well as on juveniles. In contrast, the terminal-phase male color pattern is distinct from other relatives, being vermilion to orangish brown with dark scale outlines, a white patch on the upper abdomen, and a prominent black band covering the posterior caudal peduncle and base of the caudal fin. The new species adds to the list of endemic fish species for the isolated archipelago and is an interesting case of island endemism in the region. The discovery was made during the joint 2022 collecting expedition to the archipelago, which featured a pioneering collaborative approach to an inventory of an island ichthyofauna, specifically including expert underwater photographers systematically documenting specimens in situ, before hand-collection, and then photographed fresh, tissue-sampled, and subsequently vouchered in museum collections.

Using point-of-care devices to examine covariation among blood nutritional-physiological parameters and their relationships with poxvirus infection, habitat urbanization, and male plumage coloration in house finches (Haemorhous mexicanus).

The development of inexpensive and portable point-of-care devices for measuring nutritional physiological parameters from blood (e.g., glucose, ketones) has accelerated our understanding and assessment of real-time variation in human health, but these have infrequently been tested or implemented in wild animals, especially in relation to other key biological or fitness-related traits. Here we used point-of-care devices to measure blood levels of glucose, ketones, uric acid, and triglycerides in free-ranging house finches (Haemorhous mexicanus)-a common songbird in North America that has been well-studied in the context of urbanization, nutrition, health, and sexual selection-during winter and examined (1) repeatability of these methods for evaluating blood levels in these wild passerines, (2) intercorrelations among these measurements within individuals, (3) how blood nutritional-physiology metrics related to a bird's body condition, habitat of origin (urban vs. suburban), poxvirus infection, and sex; and (4) if the expression of male sexually selected plumage coloration was linked to any of the nutritional-physiological metrics. All blood-nutritional parameters were repeatable. Also, there was significant positive covariation between concentrations of circulating triglycerides and glucose and triglycerides and uric acid. Urban finches had higher blood glucose concentrations than suburban finches, and pox-infected individuals had lower blood triglyceride concentrations than uninfected ones. Last, redder males had higher blood glucose, but lower uric acid levels. These results demonstrate that point-of-care devices can be useful, inexpensive ways of measuring real-time variation in the nutritional physiology of wild birds.

Little evidence for color- or size-based mating preferences by male strawberry poison frogs (Oophaga pumilio)

While there are many studies documenting female mating preferences across taxa, male mate choice remains relatively understudied. Male mate choice often develops when there is variation in female quality and thus the fitness benefits of mating with particular females. Specifically, males tend to prefer females with traits that confer direct fitness benefits such as large body size, which may be linked with high fecundity. Prior work has shown that females of the strawberry poison frog, Oophaga pumilio, prefer males bearing certain coloration (most often the female’s own color), and that this preference can be learned through maternal imprinting. Females have been shown to prefer larger males as well. Here we test whether similar mate preferences for color and size exist in males of this species using two-way choice tests on captive bred male O. pumilio. In each test focal males were placed in an arena with two stimulus females: either both of the same size but differing in color, or both of the same color but differing in size. We found only weak evidence for behavioral biases toward particular colors and no evidence for biases toward larger females, suggesting that males of O. pumilio do not predictably choose mates based on these female traits. Despite several aspects of their natural history that suggest males have reasons to be choosy, our findings suggest that the cost of mate rejection may outweigh any fitness benefits derived from being selective of mates. Studies of additional populations, ideally conducted on wild individuals, are needed to better understand the range of conditions under which males may exhibit mate choice and the types of traits on which they base these choices.Significance statementTo fully understand the fitness landscapes and evolutionary trajectories that result from sexual selection, we need to understand when and how the mate preferences of the two sexes act and interact. While female mate choice has been widely studied, male mate choice remains poorly understood. To help bridge this gap, we studied male mate preferences in the strawberry poison frog Oophaga pumilio, a small brightly colored frog for which female preferences for male color and size have been well-documented. We found no evidence that male O. pumilio exhibit mate preferences based on female size and little evidence for male mate preferences based on female color. This is surprising given that larger females are often more fecund, male O. pumilio are known to exhibit color-based behavioral biases in the context of male-male competition, and both sexes provide parental care.

Divergent warning patterns influence male and female mating behaviours in a tropical butterfly.

Traits under divergent ecological selection that also function during mating can be important in maintaining species boundaries. Few studies have considered mutual mate choice, where both males and females base mating decisions on the same trait. Wing colouration in Heliconius butterflies evolved as a warning signal but also functions as a mating cue. We investigated the contribution of visual preference to assortative mating in an aposematic butterfly Heliconius cydno in the context of reproductive isolation with its sympatric, visually distinct relative Heliconius melpomene. Heliconius cydno have conspicuous white bands on their forewings, whereas those of H. melpomene are red in colour. We predicted that both sexes of H. cydno contributed to assortative mating by exhibiting visual preference towards conspecific wing colouration. We analysed published and new data from preference experiments, in which males were presented with conspecific and H. melpomene females. We also recorded female responses and mating outcomes in choice experiments, involving conspecific males with either the original white or artificially painted red forewing bands. Both sexes of H. cydno responded more positively towards the conspecific colouration, and males strongly preferred females of its own colours. In contrast, male colouration did not predict mating outcomes in female choice experiments. As courtships are initiated by males in butterflies, our findings suggest that female visual preference might be of secondary importance in H. cydno. Our data also suggest that the contribution of visual preference to reproductive isolation might be unequal between H. cydno and its sympatric relative H. melpomene.

A new annual killifish, Moema beltramonorum (Cyprinodontiformes: Rivulidae) from the Amazon basin, Bolivia.

A new annual killifish species, Moema beltramonorum, is described from a seasonal swamp next to arroyo Crespo, belonging to Ro San Martin, a tributary of Ro Itnez, Amazon River basin, Bolivia. The new taxon presents an unique combination of male colour pattern characters not present in any congener, and an unique caudal fin coloration.

Ultrastructural analysis of throat dermal tissue and chromatophore components in the threespine stickleback (Gasterosteus aculeatus).

The threespine stickleback (Gasterosteus aculeatus) is an important model for studying the evolution of nuptial coloration, but histological analyses of color are largely lacking. Previous analyses of one nuptial coloration trait, orange-red coloration along the body, have indicated carotenoids are the main pigment producing this color. In addition, recent gene expression studies found variation in the correlates of throat coloration between the sexes and between populations, raising the possibility of variation in the mechanisms underlying superficially similar coloration. We used transmission electron microscopy (TEM) to investigate the histological correlates of color in the throat dermal tissue of threespine stickleback from Western North America, within and between sexes, populations, and ecotypes. Ultrastructural analysis revealed carotenoid-containing erythrophores to be the main chromatophore component associated with orange-red coloration in both males and females across populations. In individuals where some darkening of the throat tissue was present, with no obvious orange-red coloration, erythrophores were not detected. Melanophore presence was more population-specific in expression, including being the only chromatophore component detected in a population of darker fish. We found no dermal chromatophore units within colorless throat tissue. This work confirms the importance of carotenoids and the erythrophore in producing orange-red coloration across sexes, as well as melanin within the melanophore in producing darkened coloration, but does not reveal broad histological differences among populations with similar coloration.

U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER): Baseline Characteristics of a Trial Cohort Enriched for Risk of Cognitive Decline

AbstractBackgroundU.S. POINTER is a two‐year clinical trial to evaluate whether lifestyle interventions targeting multiple risk factors protect cognitive function in older adults at increased risk for cognitive decline. We describe the baseline characteristics of the U.S. POINTER clinical trial cohort overall, and before and after changes in risk factor enrichment inclusion criteria.MethodU.S. POINTER is a Phase 3, multicenter, randomized 2‐year clinical trial of two lifestyle interventions varying in intensity and format, in older adults at increased risk for cognitive decline and dementia. The study closed enrollment with 2111 individuals at 5 sites (North Carolina, Northern California, Chicagoland, Houston, Rhode Island). Eligible participants were sedentary and consumed a suboptimum diet and met other risk enrichment criteria that included first degree family history of memory impairment, and suboptimum cardiovascular health status (meeting specific cut‐points of systolic blood pressure, LDL cholesterol or hemoglobin A1c). 20 months into enrollment, risk enrichment criteria were revised to account for two other factors: older age (70‐79 years), and African American/Black or Native American race or Hispanic/Latine ethnicity.ResultMean age at baseline is 68.2 years, 31% represent communities of color, 69% are women, and 30% are not college graduates. 58% reported maternal memory loss, mean systolic blood pressure = 131 mmHg, mean total cholesterol = 193 mg/dl, mean HbA1C = 5.9%, and mean body mass index (BMI) = 29.9 kg/m2. Mean adjusted modified Telephone Interview for Cognitive Status (TICSm) score is = 37.6 (max = 50 pts), Geriatric Depression Score (GDS) is = 1.8, and Short Physical Performance Battery Chair Stand Score (SPBC) is = 3.3. Some baseline characteristics (BMI, total cholesterol, SBBP chair stand) vary by clinical site. The change to risk score enrichment criteria (Table 1) increased representation of participants from communities of color and number of males in the study cohort.ConclusionU.S. POINTER successfully enrolled 2111 participants across 5 sites who are at high risk for cognitive decline and dementia, with appropriate representation by groups typically underrepresented in clinical trials, individuals aged 75 or older, and men, with the expansion of risk score enrichment criteria.

Phenotypic characterization and genetic diversity of indigenous chickens of Jordan in comparison with native and commercial breeds ‎for conservation and breeding purposes

Indigenous chickens of Jordan are facing extinction and need genetic conservation because they were unable to commercially compete in poultry industry because of low genetic ability ‎compared to commercial layers. The study aimed to investigate phenotypic and genetic diversity ‎of village chickens in the Jordan using discriminant analyses procedures to provide a basis for ‎sustainable genetic conservation and utilization program to overcome any possible extinction. The ‎sampled chicken population of 578 one-year old chickens (125 males and 433 females) was ‎phenotypically characterized for 15 biometric and plumage traits from major cities of the three ‎regions; Middle, North, and South. The traits variations within and between breeds were detected ‎statistically by stepwise discriminant and canonical-discriminant of uni- and multivariate analyses. ‎The results showed the sampled population as village chickens in Jordan is comprised of ‎indigenous (Baladi) breed (85%) and few exotic and commercial breeds. The breeds were distinct ‎and differentiated based on phenotypic traits indicating high genetic variability. The major ‎phenotypic traits that showed significant power to differentiate breeds were comb type, body ‎weight, comb size, earlobe color, wattle size, face color and breast size in males and comb type and ‎size, body weight, face and breast size, leg color and wattle size in females. Recent and past ‎crossings, admixture or migration from exotic and commercial breeds were noted. Moreover, low ‎levels of phylogeographic structure were observed across the studied breeds. In conclusion, there is need to conserve the indigenous breed in situ and in vivo for its adaptive gene pool in coming ‎days of persisted climate change and diseases threats.

Taxonomic status of the Central Asian damselfly Calopteryx samarcandica Bartenev, 1912 (Odonata: Calopterygidae)

The taxonomic status of the Central Asian damselfly Calopteryx samarcandica was determined on the basis of molecular and phenotypic data from the Kugitang Mountains, SE Uzbekistan. Molecular analyses (COI and 18S rDNA, ITS1-5.8S rDNA-ITS2) revealed that C. samarcandica forms part of a clade that includes taxa treated in the literature as subspecies of Calopteryx splendens and/or related species. However, both mitochondrial and nuclear DNA confirmed that C. samarcandica deserves separate species status. The COI distance to C. splendens (including C. xanthostoma) is moderate (3.47%, K2P), but much greater than the internal distances between the sequences qualified in C. splendens (0.4%); this difference is supported by the low values of the barcoding gap in this genus. The rather distant separation of C. samarcandica from both C. splendens (ancilla, taurica, intermedia) and C. orientalis and the length of the samarcandica-branch recognisable in nuclear rDNA strengthen the independent position of the first species. The phylogenetic position of C. samarcandica in the genus Calopteryx remains unclear due to the low variability of nuclear rDNA markers and insufficient and partly incomparable data for other taxa. The molecular data support the phenotypic and ecological specificity of C. samarcandi­ca, defined by a diagnostic combination of its traits (male and female wing colours and large size and basal diffusion of the wing spot in males) and the conservative association with groundwater-fed natural watercourses in the mountains and foothills fringing the vast Central Asian mountain block.

Losses of sexual dichromatism involve rapid changes in female plumage colors to match males in New World blackbirds.

Differences in coloration between the sexes (sexual dichromatism) can increase or decrease in a species through evolutionary changes in either or both sexes diverging or converging in their colors. Few previous studies, however, have examined the relative rates of such changes, particularly when dichromatism is lost. Using reflectance data from 37 species of the New World blackbird family (Icteridae), we compared evolutionary rates of plumage color change in males and females when dichromatism was either increasing (colors diverging) or decreasing (colors converging). Increases in dichromatism involved divergent changes in both sexes at approximately equal rates. Decreases in dichromatism, in contrast, involved changes in females to match male plumage colors that were significantly more rapid than any changes in males. Such dramatic changes in females show how selection can differ between the sexes. Moreover, these evolutionary patterns support the idea that losses of dimorphism involve genetic mechanisms that are already largely present in both sexes, whereas increases in dimorphism tend to involve the appearance of novel sex-specific traits, which evolve more slowly. Our results have broad implications for how sexual dimorphisms evolve.