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Is thermal limitation the primary driver of elevational distributions? Not for montane rainforest ants in the Australian Wet Tropics

journal contribution
posted on 2022-08-09, 04:18 authored by Somayeh Nowrouzi, Alan N Andersen, Tom R Bishop, Simon RobsonSimon Robson
Terrestrial ectotherms are likely to be especially sensitive to rising temperatures over coming decades. Thermal limits are used to measure climatic tolerances that potentially affect ectotherm distribution. While there is a strong relationship between the critical thermal maximum (CTmax) of insects and their latitudinal ranges, the nature of this relationship across elevation is less clear. Here we investigated the combined relationships between CTmax, elevation and ant body mass, given that CTmax can also be influenced by body mass, in the World Heritage-listed rainforests of the Australian Wet Tropics. We measured the CTmax and body mass of 20 ant species across an elevational gradient from 350 to 1000 m a.s.l. Community CTmax did not vary systematically with increasing elevation and there was no correlation between elevation and elevational ranges of species. However, body mass significantly decreased at higher elevations. Despite the negative correlation between CTmax and body mass at the community level, there was no significant difference in CTmax of different-sized ants within a species. These findings are not consistent with either the climatic variability hypothesis, Rapoport’s rule or Bergmann’s rule. Models indicated that elevation and body mass had limited influences on CTmax. Our results suggest that the distribution of most montane ants in the region is not strongly driven by thermal limitation, and climate change will likely impact ant species differently. This is likely to occur primarily through changes in rainfall via its effects on vegetation structure and therefore thermal microhabitats, rather than through direct temperature changes.

Funding

Category 3 - Industry and Other Research Income

History

Volume

188

Issue

2

Start Page

333

End Page

342

Number of Pages

10

eISSN

1432-1939

ISSN

0029-8549

Location

Germany

Publisher

Springer

Language

eng

Peer Reviewed

  • Yes

Open Access

  • No

Acceptance Date

2018-03-05

External Author Affiliations

James Cook University; Charles Darwin University; University of Pretoria, South Africa

Era Eligible

  • Yes

Medium

Print-Electronic

Journal

Oecologia