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Dryad

Data from: Population-level habitat breadth varies with richness in reef fishes

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Nov 05, 2024 version files 25.38 MB
Dec 21, 2024 version files 25.38 MB

Abstract

Aim: It has been hypothesized that niche-breadth should decrease with richness, due to interactions such as competition, forcing species to specialize. This hypothesis has been tested at the community-level using species-level niche breadth estimates. However, evidence for changes in niche-breath among populations of the same species are scant. Examining this relationship among populations is crucial for understanding the role of interactions, as opposed to large-scale climate, in altering realized niche breadth.

Location: The Pacific Ocean

Time period: 1996-2010

Methods: We focus on reef fishes along a large-scale richness gradient that is not accompanied by marked environmental changes. Fishes in each site were surveyed in four distinct habitats which allow to estimate the habitat-breadth for each population. We calculated the habitat-breadth of distinct populations of 154 fish species and tested how habitat-breadth varied with richness, while controlling for the effect of abundance. We further tested the effect of traits and trait-distinctiveness on the richness-sensitivity of habitat-breadth.

Results: Habitat-breadth varied with species traits, as large and mobile species were found to be habitat generalists while schooling species habitat specialists. Importantly, habitat-breadth was negatively correlated to richness for 109 out of the 154 species, and, across all species, the relationship was highly significant. As expected from competition being the major driver, we found that species with distinct traits displayed a wider habitat breadth, but that the relationship was sensitive to the type of  trait-distinctiveness index used.

Conclusions: This is the first large-scale evidence that population-level habitat-breadth changes with richness. Results suggest that the realized niche is population specific, and that niche-breadth is reduced by local interactions such as competition. This implies that populations, specifically in rich areas, are far from using their entire fundamental niche. Therefore, the ability to predict habitat preferences in response to global change based on current habitat associations, but without accounting for species interactions, may be limited.