QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online October 10, 2003

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Irschick, D. J. Articles by Andronescu, A. Search for Related Content PubMed PubMed Citation Articles by Irschick, D. J. Articles by Andronescu, A.

Effects of loading and size on maximum power output and gait characteristics in geckos

Duncan J. Irschick^*, Bieke Vanhooydonck, Anthony Herrel and Anemone Andronescu

Department of Ecology and Evolutionary Biology, 310 Dinwiddie Hall, Tulane University, New Orleans, LA 70118, USA

View larger version (13K): [in a new window]   Fig. 1. Theoretical relationships between mass-specific power output (y axis) versus speed (x axis) if (A) mass-specific power output does not limit speed and (B) mass-specific power output limits speed. Different lines represent different loading conditions (Load A < Load B < Load C < Load D). Vmax is defined as the maximal speed the animal can attain under any circumstances; Pmax is defined as the maximal mass-specific power output the animal can attain under any circumstances.

View larger version (105K): [in a new window]   Fig. 2. Large (top, G. gecko) and small (bottom, H. garnoti) geckos with representative loads of 100% body mass. Photograph by Margarita Ramos.

View larger version (12K): [in a new window]   Fig. 3. Maximum values (means ± 1 S.E.M.) of mass-specific power (A) and speed (B) for small (H. garnoti) and large (G. gecko) geckos.

View larger version (23K): [in a new window]   Fig. 4. Scatterplots of stride length (A,C,E) and stride frequency (B,D,F) versus speed (x axis) for various loading conditions during uphill climbing for small (open circles; H. garnoti) and large (filled squares; G. gecko) geckos. Note that in none of the plots does stride length or stride frequency level off as speed increases. Values are log10-transformed.

View larger version (14K): [in a new window]   Fig. 5. Scatterplots of mass-specific power output versus speed for all strides obtained for both gecko species. (A) Mass-specific power output against speed for H. garnoti under five loading conditions (filled circles, unloaded; open squares, 2% BM; filled triangles, 100% BM; grey inverted triangles, 150% BM; grey diamonds, 200% BM). We obtained one extremely high value of mass-specific power output under the 150% loading condition. (B) Mass-specific power output against speed for G. gecko under two loading conditions (filled circles, unloaded; filled triangles, 100% BM). Extrapolation of maximal mass-specific power output to maximal speed (R. Van Damme, unpublished data) gives a value of 14.17 W kg-1 (filled circles). For both species, most of the loading conditions tend to level off near Pmax, supporting the hypothesis that mass-specific power output limits speed in these lizards.