Meta menardi and M. bourneti (Araneae, Tetragnathidae) are well known to biospeleologists as ubiquitous members of the twilight zone of most European caves. Despite the two species being relatively common, little is known about their intra‐cave ecological needs. At the same time, the question of why the two species have never been found in syntopy within the same natural cave remains. In this sense, several authors hypothesize that the two species exhibit different ecological needs in terms of temperature. In order to shed light on the ecology of the two species, we studied several populations of M. menardi and M. bourneti occurring in six caves in the Western Italian Alps (NW Italy). A series of squared plots within each cave were monitored monthly for one year. At each survey, we counted individuals occurring in each sampling squares and we collected the main environmental variables characterizing the plots. In addition, the temperature and relative humidity were continuously logged in each cave. We ran several statistical models (GLMMs) in order to relate the counts of the two species to the environmental parameters collected in the field. The distance from the cave entrance and the presence of potential prey species were the most important factors driving the relative position of both species within the cave. On the other hand, although life cycles appeared very similar, the two species seemed to exhibit different tolerance to the microclimatic variations within the cave, which emerged as the main factors determining the segregation. At least in our study area, M. bourneti tolerates broad microclimatic fluctuations and is potentially able to colonize a wide variety of caves. On the other hand, when the climatic conditions in a cave are suitable for M. menardi (narrow ranges of relatively low temperature and high humidity), M. bourneti is excluded.

Climatic segregation and intra-cave ecology of Meta menardi and M. bourneti (Araneae, Tetragnathidae)

MAMMOLA, STEFANO;ISAIA, MARCO
2014

Abstract

Meta menardi and M. bourneti (Araneae, Tetragnathidae) are well known to biospeleologists as ubiquitous members of the twilight zone of most European caves. Despite the two species being relatively common, little is known about their intra‐cave ecological needs. At the same time, the question of why the two species have never been found in syntopy within the same natural cave remains. In this sense, several authors hypothesize that the two species exhibit different ecological needs in terms of temperature. In order to shed light on the ecology of the two species, we studied several populations of M. menardi and M. bourneti occurring in six caves in the Western Italian Alps (NW Italy). A series of squared plots within each cave were monitored monthly for one year. At each survey, we counted individuals occurring in each sampling squares and we collected the main environmental variables characterizing the plots. In addition, the temperature and relative humidity were continuously logged in each cave. We ran several statistical models (GLMMs) in order to relate the counts of the two species to the environmental parameters collected in the field. The distance from the cave entrance and the presence of potential prey species were the most important factors driving the relative position of both species within the cave. On the other hand, although life cycles appeared very similar, the two species seemed to exhibit different tolerance to the microclimatic variations within the cave, which emerged as the main factors determining the segregation. At least in our study area, M. bourneti tolerates broad microclimatic fluctuations and is potentially able to colonize a wide variety of caves. On the other hand, when the climatic conditions in a cave are suitable for M. menardi (narrow ranges of relatively low temperature and high humidity), M. bourneti is excluded.
XXVIII European Congress of Arachnology
Torino
24-29 Agosto 2014
XXVIII European Congress of Arachnology - Abstract Book
Università di Torino & Museo Regionale di Scienze Naturali
95
95
http://www.eca2014.it
cave dwelling spider; ecological niche; GLMMs; phenology; Western Italian Alps
Mammola S.; Isaia M.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/152612
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact