Abstract Detail

Ecological Section

Muir, Christopher [1].

Constraint around quarter-power allometric scaling in wild tomatoes (Solanum sect. Lycopersicon; Solanaceae).

The West-Brown-Enquist (WBE) metabolic scaling theory posits that many organismal features scale predictably with body size because of selection to minimize transport costs in resource distribution networks. Many scaling exponents are quarter-powers, as predicted by WBE, but there are also biologically significant deviations that could reflect divergent adaptation. A central but untested prediction of the WBE model is that wide deviation from optimal scaling is penalized, leading to a pattern of constraint on scaling exponents. Here we demonstrate using phylogenetic comparative methods that variation in allometric scaling between mass and leaf area across 17 wild tomato taxa is weakly constrained around a value indistinguishable from that predicted by WBE, but significantly greater than 2/3 (geometric similarity model). The allometric scaling exponent was highly correlated with fecundity, water use, and drought response, suggesting that it is functionally significant and therefore could be under selective constraints. However, scaling was not strictly log-log linear, but rather declined during ontogeny in all species, as has been observed in many plant species. We caution that although our results supported one prediction of the WBE model, it did not strongly test the model in other important respects. Nevertheless, phylogenetic comparative methods like those used here are powerful, but underutilized tools for metabolic ecology that complement existing methods to adjudicate between models.

1 - University of British Columbia, Biodiversity Research Centre, 2212 Main Mall, Vancouver, BC, V6T 1Z4, Canada

Keywords:
Allometry
Metabolic scaling theory
Phylogenetic comparative metods
Solanum
Ornstein-Uhlenbeck.

Presentation Type: Oral Paper:Papers for Sections
Session: 35
Location: Salon 6/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 10:15 AM
Number: 35009
Abstract ID:1357
Candidate for Awards:None