Relationships between deep-sea invertebrates and bacterial symbionts, fueled by sulfide and methane, are well known, yet factors influencing symbiont specificity remain cryptic. For animals that obtain their symbionts from the environment, both host identity and geographic location can impact the ultimate symbiont partner. Bacterial symbionts were analyzed for 3 co-occurring species each of Bathymodiolus mussels and vestimentiferan tubeworms, from three deep methane seeps off the west coast of Costa Rica. The bacterial internal transcribed spacer...

Keystone predation can be a determinant of community structure, including species diversity, but factors underlying “keystoneness” have been minimally explored. Using the system in which the original keystone, the sea star Pisaster ochraceus, was discovered, we focused on two potential (but overlapping) determinants of keystoneness: intrinsic traits or state variables of the species (e.g., size, density), and extrinsic environmental parameters (e.g., prey productivity) that may provide conditions favorable for keystone predator evolution. Using a comparative-experimental...

How the microbiome interacts with hosts across evolutionary time is poorly understood. To address this question, datasets comprised of many host species are required to conduct comparative analyses. Here, we have analyzed 142 intestinal microbiome samples from 92 birds belonging to 74 species from Equatorial Guinea, using the 16S rRNA gene. Using four definitions for microbial taxonomic units (97%OTU, 99%OTU, 99%OTU with singletons removed, ASV), we conducted alpha and beta diversity analyses and used phylogenetic...

Background Numerous deep-sea invertebrates have formed symbiotic associations with internal chemosynthetic bacteria in order to harness inorganic energy sources typically unavailable to most animals. Despite success in nearly all marine habitats and their well-known associations with photosynthetic symbionts, Cnidaria remain without a clear dependence on hydrothermal vents and chemosynthetic bacterial symbionts specifically. Results A new chemosynthetic symbiosis between the sea anemone Ostiactis pearseae (Daly & Gusmão, 2007) and intracellular bacteria was discovered at ~3700 m...

Deep-sea methane seeps are dynamic sources of greenhouse gas production and unique habitats supporting ocean biodiversity and productivity. Here, we demonstrate new animal-bacterial symbioses fueled by methane, between two undescribed species of annelid (a serpulid Laminatubus and sabellid Bispira) and distinct methane-oxidizing Methylococcales bacteria. Worm tissue delta 13C of -44 to -58 per mil suggested methane-fueled nutrition for both species and shipboard experiments revealed active assimilation of 13C-labelled CH4 into animal biomass, occurring via engulfment...

Many species of birds show distinctive seasonal breeding and nonbreeding plumages. A number of hypotheses have been proposed for the evolution of this seasonal dichromatism, specifically related to the idea that birds may experience variable levels of sexual selection relative to natural selection throughout the year. However, these hypotheses have not addressed the selective forces that have shaped molt, the underlying mechanism of plumage change. Here, we examined relationships between life-history variation, the evolution of...