Sequential introgression of a carotenoid processing gene underlies sexual ornament diversity in a genus of manakins.

In a hybrid zone between two tropical lekking birds, yellow male plumage of one species has introgressed asymmetrically replacing white plumage of another via sexual selection. Here, we present a detailed analysis of the plumage trait to uncover its physical and genetic bases and trace its evolutionary history. We determine that the carotenoid lutein underlies the yellow phenotype and describe microstructural feather features likely to enhance color appearance.

Spread of yellow-bill-color alleles favored by selection in the long-tailed finch hybrid system.

Carotenoid pigments produce the yellow and red colors of birds and other vertebrates. Despite their importance in social signaling and sexual selection, our understanding of how carotenoid ornamentation evolves in nature remains limited. Here, we examine the long-tailed finch Poephila acuticauda, an Australian songbird with a yellow-billed western subspecies acuticauda and a red-billed eastern subspecies hecki, which hybridize where their ranges overlap.

Detection of Porphyrins in Hair Using Capillary Liquid Chromatography-Mass Spectrometry.

Unlike humans, some animals have evolved a physiological ability to deposit porphyrins, which are pigments produced during heme synthesis in cells, in the skin and associated integument such as hair. Given the inert nature and easiness of collection of hair, animals that present porphyrin-based pigmentation constitute unique models for porphyrin analysis in biological samples. Here we present the development of a simple, rapid, and efficient analytical method for four natural porphyrins (uroporphyrin I, coproporphyrin I, coproporphyrin III and protoporphyrin IX) in the Southern flying squirrel Glaucomys volans, a mammal with hair that fluoresces and that we suspected has porphyrin-based pigmentation.

A combination of red structural and pigmentary coloration in the eyespot of a copepod.

While the specific mechanisms of colour production in biological systems are diverse, the mechanics of colour production are straightforward and universal. Colour is produced through the selective absorption of light by pigments, the scattering of light by nanostructures or a combination of both. When copepods were fed a carotenoid-limited diet of yeast, their orange-red body coloration became faint, but their eyespots remained unexpectedly bright red.

A response to Justen et al. 2020: Estimating hybridization rates in the wild: Easier said than done?

We consider four key challenges related to estimating per-individual rates of hybridization in wild birds: (1) what is the meaning of the term "hybrid"?, (2) the importance of distinguishing between shared DNA sequences and on-going hybridization between populations, (3) the perils of focusing exclusively on known hybrid zones, and (4) the implications of very low rates of per individual hybridization. Because our focus is on using phenotype to recognize hybrids, we define a hybrid as an individual with a phenotype that is intermediate between two parental species. We emphasize the value of quantifying the rate of between-species mating that is ongoing in current populations and distinguish this endeavor from estimates of gene flow between populations based on genomic analysis, which can reflect both current and ancient hybridization.

Ultraviolet irradiation alters the density of inner mitochondrial membrane and proportion of inter-mitochondrial junctions in copepod myocytes.

The efficient production of energy via oxidative phosphorylation is essential to the growth, survival, and reproduction of eukaryotes. The behavior (position of, and communication between, mitochondria) and morphology of mitochondria play key roles in efficient energy production and are influenced by oxidative stressors such as ultraviolet (UV) radiation. We tested the hypothesis that mitochondria change their behavior and morphology to meet energetic demands of responding to changes in oxidative stress.

Birds rarely hybridize: A citizen science approach to estimating rates of hybridization in the wild.

The rate of hybridization among taxa is a central consideration in any discussion of speciation, but rates of hybridization are difficult to estimate in most wild populations of animals. We used a successful citizen science dataset, eBird, to estimate the rates of hybridization for wild birds in the United States. We calculated the frequency at which hybrid individuals belonging to different species, families, and orders of birds were observed.

Spiders have rich pigmentary and structural colour palettes.

Elucidating the mechanisms of colour production in organisms is important for understanding how selection acts upon a variety of behaviours. Spiders provide many spectacular examples of colours used in courtship, predation, defence and thermoregulation, but are thought to lack many types of pigments common in other animals. Ommochromes, bilins and eumelanin have been identified in spiders, but not carotenoids or melanosomes.