Shared environmental responses drive co‐occurrence patterns in river bird communities

Abstract

Positive or negative patterns of co‐occurrence might imply an influence of biotic interactions on community structure. However, species may co‐occur simply because of shared environmental responses. Here, we apply two complementary modelling methodologies – a probabilistic model of significant pairwise associations and a hierarchical multivariate probit regression model – to 1) attribute co‐occurrence patterns in 100 river bird communities to either shared environmental responses or to other ecological mechanisms such as interaction with heterospecifics, and 2) examine the strength of evidence for four alternative models of community structure. Species co‐occurred more often than would be expected by random community assembly and the species composition of bird communities was highly structured. Co‐occurrence patterns were primarily explained by shared environmental responses; species’ responses to the environmental variables were highly divergent, with both strong positive and negative environmental correlations occurring. We found limited evidence for behaviour‐driven assemblage patterns in bird communities at a large spatial scale, although statistically significant positive associations amongst some species suggested the operation of facilitative mechanisms such as heterospecific attraction. This lends support to an environmental filtering model of community assembly as being the principle mechanism shaping river bird community structure. Consequently, species interactions may be reduced to an ancillary role in some avifaunal communities, meaning if shared environmental responses are not quantified studies of co‐occurrence may overestimate the role of species interactions in shaping community structure.

Competition‐driven niche segregation on a landscape scale: Evidence for escaping from syntopy towards allotopy in two coexisting sibling passerine species

“…Bird communities examined by Royan et al. () or Ricklefs et al. () were represented by sets of phylogenetically distant species for which the interspecific competition does not probably act as a mechanism limiting their coexistence.…”

Specialization and niche overlap across spatial scales: Revealing ecological factors shaping species richness and coexistence in Australian songbirds

“…While niche partitioning is assumed to be most important on fine spatial scales shaping local coexistence of species, the role of abiotic conditions and historical effects should be more prominent on coarser regional scales and thus shaping spatial variation in species richness (Belmaker & Jetz, ; Devictor et al, ; Ferger, Schleuning, Hemp, Howell, & Böhning‐Gaese, ; Fergnani & Ruggiero, ; Hawkins et al, ; Ricklefs, ; Royan et al, ; Whittaker, Willis, & Field, ). However, most studies fail to work across several spatial scales and thus fail to identify relative roles of niche partitioning, abiotic conditions and historical effects on different scales (Belmaker et al, ; Ricklefs, ).…”

Dynamic species co‐occurrence networks require dynamic biodiversity surrogates

“…One of the most recent advances in co‐occurrence has been to quantify the contribution of niche overlap (i.e. the degree of similarity in species–environmental relationships) to co‐occurrence through individualistic species distribution modelling that incorporates both environmental drivers and species interactions (Royan et al ). Models might then be used to derive more realistic networks of co‐occurrence that assist with predicting changes to the community (Gotelli et al , Araújo et al ).…”