A trait database and updated checklist for European subterranean spiders

Abstract

Species traits are an essential currency in ecology, evolution, biogeography, and conservation biology. However, trait databases are unavailable for most organisms, especially those living in difficult-to-access habitats such as caves and other subterranean ecosystems. We compiled an expert-curated trait database for subterranean spiders in Europe using both literature data (including grey literature published in many different languages) and direct morphological measurements whenever specimens were available to us. We started by updating the checklist of European subterranean spiders, now including 512 species across 20 families, of which at least 192 have been found uniquely in subterranean habitats. For each of these species, we compiled 64 traits. The trait database encompasses morphological measures, including several traits related to subterranean adaptation, and ecological traits referring to habitat preference, dispersal, and feeding strategies. By making these data freely available, we open up opportunities for exploring different research questions, from the quantification of functional dimensions of subterranean adaptation to the study of spatial patterns in functional diversity across European caves.

Species conservation profiles of the endemic spiders Troglohyphantes (Araneae, Linyphiidae) from the Alps and the North-western Dinarides

“…The ecology and life history of this species is unknown. This spider shows minor specialisation to subterranean life (Mammola et al 2022a).…”

“…- This species shows a high degree of specialisation to deep subterranean habitats, with absence of pigmentation and eye reduction (Mammola et al 2022a).…”

Species conservation profiles of the endemic spiders Troglohyphantes (Araneae, Linyphiidae) from the Alps and the north-western Dinarides

“…The habitats colonised by T. lessinensis are as yet not threatened by direct human activities. Specimens are characterised by a pronounced microphthalmy (Mammola et al 2022a).…”

Towards a mechanistic explanation of Island biogeography using subterranean animal communities

“…Island trait spaces converge across islands First, we explored the functional diversity patterns of the subterranean communities in the Canary Islands relating the properties of each trait space to the age and stage of the geological cycle for each island. Since the subterranean environment imposes a similar ecological filter across islands (i.e., permanent darkness and scarcity of food), we expected a functional convergence of trait spaces across islands (Gibert & Deharveng 2002;Trontelj et al 2012;Mammola et al 2022). Yet, we expect some degree of polarisation of the trait space according to the ontogenetic stage young (La Palma and El Hierro), mature (La Gomera, Tenerife, and Gran Canaria), and senescent (Fuerteventura and Lanzarote) islands.…”

“…Collecting ecological data in these environments is notoriously challenging (Mammola et al 2021a). However, once the exploration and sampling impediments are overcome, our efforts are compensated by the set of unique properties that make subterranean habitats ideal laboratories for eco-evolutionary research (Mammola & Martinez 2021) including their discrete nature largely preventing long-range migration (Mammola,2019) and the presence of relatively simple communities showing high trait convergence (Gibert & Deharveng 2002;Trontelj et al 2012;Mammola et al 2022). Given that subterranean habitats in oceanic islands are de facto "islands within islands" (Esposito et al 2015), they should represent the perfect model system to explore broad questions within the realm of island biogeography (Culver 1970(Culver , 1971Fattorini et al 2016;Balog et al 2020).…”