Trait–environment relationships of hydroids (Cnidaria: Hydrozoa) across large spatial and environmental gradients in the Atlantic Ocean

Abstract

AbstractAimThe aim was to test trait–environment relationships in hydroids across large spatial and environmental gradients and to evaluate associations between traits, environmental variables, space and phylogeny.LocationAtlantic Ocean and adjacent polar seas.Time periodPresent day.Major taxa studiedHydrozoa.MethodsTrait–environment relationships and their spatial and phylogenetic contexts were assessed in hydroids by using a combination of a fourth‐corner test and extended‐RLQ approach, in a multivariate ordination method that uses five matrices: (1) species across sites, (2) environmental data across sites, (3) traits across species, (4) latitude and longitude for each site, and (5) phylogenetic distance among species. We based our analyses on 3680 records of 431 species distributed at 1440 sites, 16 species traits, nine environmental variables and a phylogenetic tree of the studied species.ResultsHydroid traits are significantly correlated with environmental variables and geographical space, and hydroid phylogeny is correlated with the environment and geographical space. More evidently, we observed an increased presence of larger species (taller, more branched, with greater base diameter and polysiphonic) at sites richer in nitrate and silicate, with higher dissolved oxygen, lower temperatures, lower salinities and lower current velocities. The observation of phylogenetically related species with similar traits and distributions corroborates that historical processes interact with the environment in determining community assembly and explaining patterns of distribution of species traits.Main conclusionsSeveral environmental variables combined affect the distribution of hydroid traits, which are also influenced by spatial and historical factors. In the first analysis of its kind for hydrozoans, we have provided an overview of how hydroids are distributed across environments according to their traits and revealed the spatial and phylogenetic components of these trait–environment relationships.