Modelling the future spread of native and alien congeneric species in subterranean habitats — the case of Meta cave-dwelling spiders in Great Britain

Abstract

Abstract:The threshold zones between the epigean and hypogean environments are generally characterized by less harsh ecological conditions than deep subterranean habitats, and usually support a greater abundance of organisms. Transitional habitats such as these should be more easily colonised by alien species, especially by those possessing exaptations suitable for subterranean life. In spite of this, few studies have been conducted to unravel the ecological dynamics between native and alien species in the habitats situated at the epigean/hypogean interface. A unique test case is offered by cave-dwelling Meta orb-weaver spiders in Great Britain (Araneae: Tetragnathidae). One species, M. menardi, is a widespread native, whilst M. bourneti is believed to be a recently introduced (1940s) species, that has since become established in the south-eastern part of the country. Species distribution models (SDM) were used to predict current and future habitat suitability for the two species, generating hypotheses regarding their distribution in different global warming scenarios.Model projections indicate that the two species respond to similar environmental variables. Seasonal temperature variations at the surface and elevation are the main factors explaining the distribution of both species, whereas annual precipitation, daily temperature range and limestone distribution contributed little to the model performance. It is predicted that due to climate change, there will be poleward shifts in the ranges of both species. However, the native species M. menardi will primarily be able to exploit suitable areas which will appear northward to their current distribution, and M. bourneti will colonise empty niches left available by its congeneric. The analytical framework employed in this paper may be easily adapted to other subterranean systems and species, stimulating future studies focusing on the distribution of native and alien species in extreme environments.global warming, species distribution models, cave, alien species, MaxEnt, subterranean biology Mammola S., 2017. Modelling the future spread of native and alien congeneric species in subterranean habitats -the case of Meta cave-dwelling spiders in Great Britain. International

Finding answers in the dark: caves as models in ecology fifty years after Poulson and White

“…Recently, some attention has also been given to investigating biological invasions in subterranean habitats (Wynne et al 2014). Due to their harsh ecological characteristics, deep subterranean habitats have been regarded as significant ecological filters for the establishment of alien species (Mammola 2017) and, thus, the contribution of subterranean studies to the understanding of biological invasions has been limited. Some authors have documented the spread of certain alien species in caves, emphasizing their potential ecological impact on native communities (Table 2).…”

A synthesis on cave-dwelling spiders in Europe

“…Finally, at least three cave‐associated species are alien to Europe, namely Psilochorus simoni (Berland) (Pholcidae), Nesticella mogera (Yaginuma) and Eidmannella pallida (Emerton) (Nesticidae) (Mammola, ; Nentwig, ; Nentwig et al., ). Psilochorus simoni is native to North America and it has been introduced in Europe at least once, being now established in several European countries (Fürst & Blandenier, ; Nentwig et al., ).…”

“…Climatic‐driven changes in the distribution range of most subterranean species have been seldom studied (e.g., Brandmayr & Pizzolotto, ; Brandmayr et al., ; Mammola & Leroy, ; Sánchez‐Fernández et al., ). Regarding spiders, significant latitudinal shifts are expected within high dispersal species (Mammola, ; Mammola & Isaia, ). On the other hand, contractions in the distribution range can be expected within most restricted cryophilic taxa (Mammola, Goodacre, & Isaia., ).…”

Applying species distribution models to caves and other subterranean habitats

“…The majority of SDM studies of above‐ground (epigean) ecosystems are based on the 19 ‘bioclimatic’ variables, which constitute a set of variables derived from monthly means and extreme temperatures and rainfall regimes (Table 3); see Kriticos et al (2012, 2014), Title and Bemmels () and for further additions to the standard set of bioclimatic variables. Bioclimatic variables are available at different spatial resolutions, from coarse (10’) to very fine (30’’), for a current time scale (1970 – 2000; Fick and Hijmans ) and for several past and future scenarios (Hijmans et al 2005, Kriticos et al 2012).…”