History, island area and habitat availability determine land snail species richness of Aegean islands

摘要: Summary Aim We examined the species-area relation of Aegean land snails, comparing different models to describe relation. By examining those factors other than area that may also affect species richness, we tested whether snail fauna was more influenced by equilibrial migration and colonization processes, or rather is conservative relictual. Location The archipelago (Greece). Methods Sixty-five islands were examined. Data taken from own collections literature sources. Multiple regression analysis used test null hypothesis no relationship between richness island area, elevation, distance next larger island, presence extent calcareous substrate. Results single most important factor determining number area. While colonization-extinction dynamics have frequently been cited explain this result, conclusion not tenable in study as it contradicted being related islands’ distances neighbouring islands, after accounting for affecting number. found habitat diversity affected even effects area: both increased elevation greater substrate on resulted higher This effect likely due fact particular ecological conditions probability could survive an island. We compared utility power extreme-value function gave substantially same results. However, fitting model using nonlinear questionable utility. Main conclusions conclude relictual, equilibrial. unusually high Crete consistent with conclusion. a currently united which separated into at least six smaller 7–9 million years during Neogene. Our results are still hosts large endemic these paleoislands, resulting total excess what would be expected based alone. Resume Nous avons examine la d’espece-superficie de mollusques terrestres 65 iles l’archipel egeen (Grece). Le facteur le plus determinant nombre d’especes etait superficie. Tandis que dynamique ete frequemment citee pour expliquer ce resultat, cette n’etait pas dans etude car elle contredite par n’etant lie aux des vers grandes voisines, apres avoir deduit les effets d’autres facteurs affectant d’especes. Nous concluons faune l’Egee est relictuale, non equilibriale. Le exceptionnellement eleve en accord avec une ile actuellement unie qui separee au moins petites periode millions d’annees pendant neogene. Nos resultats sont conformes l’hypothese accueille toujours un grand endemiques ces paleoiles, ayant resultat au-dessus serait prevu etant base seulement sur superficie. Nous egalement constate diversite d’habitats affecte richesse meme soustrait superficie: grande altitude et superficie du substrat calcaire ont eu comme consequence Cet effet tres probablement fait ecologiques particulieres augmentent probabilite l’espece particuliere pourrait survivre ile. Finalement nous compare l’utilite modeles fonction puissance d’extreme-valeur tous deux donne sensiblement memes resultats. Cependant, appliquant lineaire modele d’une utilite incertaine.