Intraspecific competition, not predation, drives lizard tail loss on islands

Yuval Itescu*, Rachel Schwarz, Shai Meiri, Panayiotis Pafilis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


Tail autotomy is mainly considered an antipredator mechanism. Theory suggests that predation pressure relaxes on islands, subsequently reducing autotomy rates. Intraspecific aggression, which may also cause tail loss, probably intensifies on islands due to the higher abundance. We studied whether tail autotomy is mostly affected by predation pressure or by intraspecific competition. We further studied whether predator abundance or predator richness is more important in this context. To test our predictions, we examined multiple populations of two gecko species: Kotschy's gecko (Mediodactylus kotschyi; mainland and 41 islands) and the Mediterranean house gecko (Hemidactylus turcicus; mainland and 17 islands), and estimated their abundance together with five indices of predation. In both species, autotomy rates are higher on islands and decline with most predation indices, in contrast with common wisdom, and increase with gecko abundance. In M. kotschyi, tail-loss rates are higher on predator and viper-free islands, but increase with viper abundance. We suggest that autotomy is not simply, or maybe even mainly, an antipredatory mechanism. Rather, such defence mechanisms are a response to complex direct and indirect biotic interactions and perhaps, in the case of tail autotomy in insular populations, chiefly to intraspecific aggression.

Original languageEnglish
Pages (from-to)66-74
Number of pages9
JournalJournal of Animal Ecology
Issue number1
StatePublished - 1 Jan 2017


FundersFunder number
Greek Ministry of Environment, Energy, and Climate Change20305/824
Petros Lymberakis and Manolis Papadimitrakis
Israel Science Foundation1005/12
Tel Aviv University


    • autotomy
    • defence mechanisms
    • geckos
    • intraspecific aggression
    • islands
    • lizards
    • population abundance
    • predation pressure


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