The Subhabitat Dependence of Biogeographic Pattern

Ricardo A Scrosati,Julius A Ellrich,Matthew J Freeman

doi:10.3389/fevo.2020.550612

Ricardo A Scrosati, Julius A Ellrich + Show 1 more

Open Access

https://doi.org/10.3389/fevo.2020.550612

Copy DOI

Abstract

We introduce and test the subhabitat dependence hypothesis (SDH) in biogeography. This hypothesis posits that biogeographic pattern within a region differs when determined with species abundance data from different subhabitat types. It stems from the notion that the main abiotic factors that drive species distribution in different subhabitat types across a biogeographic region often vary differently across space. To test the SDH, we measured the abundance of algae and sessile invertebrates in two different subhabitats (high intertidal zone and mid-intertidal zone) at eight locations along the Atlantic Canadian coast. We conducted multivariate analyses of the species abundance data to compare alongshore biogeographic pattern between both zones. For both subhabitat types, location groupings based on community similarity not always responded to geographic proximity, leading to biogeographic patchiness to some extent. Nonetheless, both biogeographic patterns were statistically unrelated, thus supporting the SDH. This lack of concordance was most evident for southern locations, which clustered together based on high-intertidal data but showed considerable alongshore patchiness based on mid-intertidal data. We also found that the ordination pattern of these eight locations based on sea surface temperature data was significantly related to biogeographic pattern for the mid-intertidal zone but not for the high intertidal zone. This finding supports the rationale behind the SDH due to the longer periods of submergence experienced by the mid-intertidal zone. Overall, we conclude that biogeographic pattern within a region can depend on the surveyed subhabitat type. Thus, biological surveys restricted to specific subhabitats may not properly reveal biogeographic pattern for a biota as a whole or even just for other subhabitats. As many studies generate biogeographic information with data only for specific subhabitats, we recommend testing the SDH in other systems to determine its domain of application.

Highlights

A central goal of biogeography is to understand species distribution patterns within biogeographic regions
We identified 22 sessile species in total, 12 of which occurred at both elevation zones, one only at the high intertidal zone, and nine only at the mid-intertidal zone (Table 2)
At the mid-intertidal zone, the biogeographic pattern along the northern half of the studied coastal range was not too different from that at the high intertidal zone, as L2 and L4 clustered together while L1 and L3 differed from that cluster, differing between themselves more

Summary

Introduction

A central goal of biogeography is to understand species distribution patterns within biogeographic regions. A first step typically involves describing biogeographic pattern in terms of spatial groupings of locations based on species abundance data. Many terrestrial and aquatic environments have been surveyed around the world. For reasons related to scientific interest or logistical constraints, comprehensive surveys are not always done. Biogeographic patterns for regional biotas are sometimes necessarily inferred based on subsets of data. Many biogeographic surveys have focused only on specific groups of organisms, such as birds

Methods

Results

Conclusion