Cave exploitation by an usual epigean species: a review on the current knowledge on fire salamander breeding in cave

Raoul Manenti,Enrico Lunghi,Gentile Francesco Ficetola

doi:10.21426/b632136017

Abstract

Author(s): Manenti, Raoul; Lunghi, Enrico; Ficetola, Gentile Francesco | Abstract: The fire salamander (Salamandra salamandra) is a relatively common epigean amphibian, widely distributed throughout Europe, which usually gives birth to aquatic larvae. Even if epigean streams represent the most common places in which the species breeds, in some countries caves with underground waters are also used. To improve our understanding of the habitat features allowing successful breeding of salamanders in underground sites, we combined an exhaustive review of the available literature, especially the grey one, with direct observations performed from 2008 to 2017 in several natural and artificial caves of Lombardy, Liguria and Tuscany (Italy), Ariege and Provence (France). We provide a synthesis of published and unpublished caves in which the fire salamander breeding has been observed, along with a synthesis of the investigated ecological, behavioural and morphological traits. The use of underground sites is reported in several published papers and appears to be a common phenomenon not limited to single karst areas. The absence of predators, the relative stability of the aquatic habitats and the possibility to exploit new ecological resources are environmental factors that favour the breeding of the fire salamander. Our synthesis suggests that breeding of fire salamanders in caves is not a random event, but a widespread phenomenon that may be linked to specific biogeographical factors. Further insights may be obtained by performing genetic analyses on both cave and epigean populations, and considering larger landscape scales for ecological studies as well. Gene flow between salamanders that breed in caves and in streams probably occurs, but on the other hand, assortative mating might limit it, thus allowing the conservation of local adaptations driving successful cave colonisation.

Highlights

Underground systems with groundwater play a fundamental role for humans as they represent a major source of potable water supply in many countries and, globally, the largest source of available freshwater (Culver and Pipan 2014)
Overall the current knowledge on fire salamander breeding in caves, stresses that local adaptations and phenotypic plasticity act in concert during the colonization of caves, highlighting that a strong phenotypic plasticity is a key trait for survival in these extreme environments
Given that fire salamanders are quite mobile, (Ficetola 2012; Schmidt et al 2007; Schulte et al 2007) and caves and streams often occur within the dispersion capability of a single population, gene flow probably occurs between salamanders that breed in caves and in streams

Summary

Introduction

Underground systems with groundwater play a fundamental role for humans as they represent a major source of potable water supply in many countries and, globally, the largest source of available freshwater (Culver and Pipan 2014). Since the prehistory, the interest for groundwater has focused on the operational management for potable or agricultural supply (Balland 1992). Underground environments such as caves and their aquifers, natural springs and draining galleries, can be of particular interest from a zoological perspective (Stoch et al 2009). Many subterranean aquatic habitats contain exceptional communities of organisms (Culver and Pipan 2009), which are receiving an increasing interest by zoologists as they can provide interesting ecological and evolutionary insights. Subterranean habitats have a high potential to permit the investigation of many aspects of modern ecology and biology (Pipan and Culver 2013). It is important to recognize that underground habitats are not a closed system (Romero 2009): besides the exchange of abiotic components (e.g. chemicals, air and water) with outdoor environments, many organisms (more or less occasionally) move in and out caves, being entirely or for a part of their life cycles linked to underground environments (Lunghi et al 2017)

Objectives

Methods

Results

Conclusion