Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Evolutionary predictors of the specific colors of birds.(National Academy of Sciences, 2023-08-14) Delhey K; Valcu M; Muck C; Dale J; Kempenaers B; Losos JAnimal coloration is one of the most conspicuous aspects of human-perceived organismal diversity, yet also one of the least understood. In particular, explaining why species have specific colors (e.g., blue vs. red) has proven elusive. Here, we quantify for nearly all bird species, the proportion of the body covered by each of 12 human-visible color categories, and test whether existing theory can predict the direction of color evolution. The most common colors are black, white, gray and brown, while the rarest are green, blue, purple, and red. Males have more blue, purple, red, or black, whereas females have more yellow, brown, or gray. Sexual dichromatism is partly due to sexual selection favoring ornamental colors in males but not in females. However, sexual selection also correlated positively with brown in both sexes. Strong social selection favors red and black, colors used in agonistic signaling, with the strongest effects in females. Reduced predation risk selects against cryptic colors (e.g., brown) and favors specific ornamental colors (e.g., black). Nocturnality is mainly associated with brown. The effects of habitat use support the sensory drive theory for camouflage and signaling. Darker colors are more common in species living in wet and cold climates, matching ecogeographical rules. Our study unambiguously supports existing theories of color evolution across an entire class of vertebrates, but much variation remains unexplained.Item Wildlife trade targets colorful birds and threatens the aesthetic value of nature(Elsevier Inc, 2022-10-10) Senior RA; Oliveira BF; Dale J; Scheffers BRA key component of nature's contribution to people is aesthetic value. Charismatic species rally public support and bolster conservation efforts. However, an insidious aspect to humanity's valuation of nature is that high value also drives wildlife trade, which can spearhead the demise of prized species. Here, we explore the antagonistic roles of aesthetic value in biodiversity conservation by using novel metrics of color to evaluate the aesthetics of the most speciose radiation of birds: passerines (i.e., the perching birds). We identify global color hotspots for passerines and highlight the breadth of color in the global bird trade. The tropics emerge as an epicentre of color, encompassing 91% and 65% of the world's most diverse and most uniquely colored passerine assemblages, respectively. We show that the pet trade, which currently affects 30% of passerines (1,408/5,266), traverses the avian phylogeny and targets clusters of related species that are uniquely colored. We identify an additional 478 species at risk of future trade based on their coloration and phylogenetic relationship to currently traded species-together totaling 1,886 species traded, a 34% increase. By modeling future extinctions based on species' current threat status, we predict localized losses of color diversity and uniqueness in many avian communities, undermining their aesthetic value and muting nature's color palette. Given the distribution of color and the association of unique colors with threat and trade, proactive regulation of the bird trade is crucial to conserving charismatic biodiversity, alongside recognition and celebration of color hotspots.