Quantifying troglomorphism in hyperspace

Many ecological and evolutionary studies require to quantify the degree of adaptation subterranean species caves or other systems. In 1962, Kenneth A. Christiansen (1924–2017) coined term “troglomorphism” illustrate process suite adaptive traits organisms (“troglomorphic traits” “troglomorphies”) (Christiansen 1962). Although this was proposed in a paper published French, its derivatives (e.g. “troglobiomorphism”) became widely adopted jargon biology. Yet, after decades work countless discussions around subtle meanings term, there is still no consensus on how best troglomorphism simple operational way support eco-evolutionary research. recent interview, Boris Sket made excellent point that “ nothing [makes] sense speleobiology without comparison cave animals with 'normal' epigean ones ” (Lu?i? 2021). Building idea, we contend one could continuous scale within given group (e.g., family genus) as functional distance each phylogenetically closest surface “average” (depending whether phylogenetic information available not). We approach using spiders genus Troglohyphantes , well-studied for which both phylogeny are (Isaia et al. 2017, Mammola 2020) . tested two approaches: i) quantifying morphological surface-dwelling relative; ii) kernel density n-dimensional hypervolume ( sensu Blonder 2014) construct morphospace occupied by all their from centroid species. To test effectiveness these alternative methods, compare varies relation habitat (deep vs entrances interstitial habitats) range size. suggest our be applied any relative known, allowing explore questions specialization community relates local environmental conditions, interspecific interactions, more.