Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: May 01, 2000

Variation in the Pattern of Predator-Induced Damage to Tadpole Tails

and
Page Range: 390 – 401
DOI: 10.1643/0045-8511(2000)000[0390:VITPOP]2.0.CO;2
Save
Download PDF

Abstract

Tadpoles in nature are often found with injured tails. We introduce a planimetric technique for compiling data on the injuries sustained by individual tadpoles, which allows us to visualize and quantify the tail damage sustained by a population as a whole. We have used this technique to compare the pattern and severity of damage in tadpoles from seven species (Ascaphus truei, Bufo americanus, Phyllomedusa tomopterna, Pseudacris crucifer, Rana catesbeiana, Rana sylvatica, and Rhinophrynus dorsalis) that differ in microhabitat use (benthic vs pelagic), tail morphology (filamentous vs nonfilamentous) and palatability to predators. We also examined differences in tail damage across developmental stages. Finally, we compared interpopulation variation for R. sylvatica tadpoles from six separate ponds. The tail tip was the most commonly damaged area in all tadpoles, although the pattern and severity of injury varied greatly across species. Unpalatable, benthic larvae sustained small nicks around the margin of the tail, whereas pelagic and palatable species more often had the tail tip sheared off caudally. Little damage was found in any species in the anterior portion of the tail, where most thrust is generated during swimming. Only one species, A. truei, exhibited increased tail damage as the tadpoles aged. Later stage P. crucifer and R. sylvatica larvae in contrast, had significantly less tail damage than younger stage conspecifics. Although this could be the result of different healing rates at different stages, alternatively it suggests that for these species, survivorship is ultimately reduced in individuals that lose a substantial part of the tail when they are young.

  • Download PDF
Copyright: The American Society of Ichthyologists and Herpetologists
Fig. 1.
Fig. 1.

Repeatability in scoring tail damage, showing good agreement between two observers in the pattern and amount of tail damage. (A–B) Composite images from Kassina sp. (n = 9); (C–D) Phrynomantis microps (n = 19). Tail damage was scored independently by J. Glos (A,C) and by J. Blair (B,D). The average percent of tail area damaged recorded are (A) 4.1 ± 2.8, (B) 3.5 ± 1.7, (C) 2.5 ± 0.8, (D) 2.8 ± 1.1. Because of the smaller sample size, the opacity was set at a higher level (20% for Kassina and 15% for Phrynomantis) than in the following figures (Tadpole drawings provided by M.-O. Rödel)


Fig. 2.
Fig. 2.

(A) False colored composite images of tail damage for seven species, arranged from the species with the most (Pseudacris crucifer) to the species with the least (Bufo americanus) severely damaged tails. Sample sizes for each species are given in the Appendix. Source of outline drawings: Johnson (1987) for P. crucifer, Rana sylvatica, Rana catesbeiana, and B. americanus; Stebbins (1966) for Ascaphus truei; Duellman and Trueb (1986) for Rhinophrynus dorsalis; and Cannatella (1982) for Phyllomedusa tomopterna. (B) Intraspecific comparison of injury in younger, stage 26–34 (A), versus older, stage 35–43 (B), P. crucifer tadpoles


Fig. 4.
Fig. 4.

Scatterplots of percent of the tadpole tail with damage across developmental stage for Rana sylvatica collected at five sites in Nova Scotia and one site in Maryland


Fig. 5.
Fig. 5.

Scatterplots of the percent of the tadpole tail damaged versus developmental stage for each species. Sample sizes are given in the Appendix


Fig. 3.
Fig. 3.

Composite images of tail damage for Rana sylvatica tadpoles collected in five Nova Scotia ponds (n = 100 for each population)


Accepted: Sep 16, 1999