BioClim variables used in modelling the bioclimatic niches.

<p>0.7, 0.8, 0.9 refer to threshold of the maximum correlation (Spearman’s rank) between BioClim variables value beyond which the data were considered as independent.</p><p>*Isothermality = [Mean Diurnal Range (Mean of monthly (max temp–min temp)) / Temperature Annual Range]</p><p>BioClim variables used in modelling the bioclimatic niches.</p

Bayesian phylogenetic trees of the focal species complexes using concatenated alignments for 28S and COI gene fragment.

<p>The numbers on nodes indicate posterior probabilities for Bayesian trees and bootstrap support values for maximum likelihood trees. Patristic, K2P and uncorrected p-distances between A and B species within <i>N</i>. <i>krameri</i> and <i>N</i>. <i>spinulifemur</i> are 0.34, 0.14, 0.12 and 0.36, 0.19, 0.16, respectively. Coloured dots at some terminals indicate localities of co-occurrences with the respective species. The species are: <i>Niphargus krameri</i> A (NKA, red), <i>Niphargus krameri</i> B (NKB, blue), <i>Niphargus spinulifemur</i> A (NSA, green), and <i>Niphargus spinulifemur</i> B (NSB, yellow).</p

Evidence for clumped distribution of focal species.

<p>* NN Ratio = observed mean distance/expected mean distance, if NNR<1 then distribution is clumped, if NNR>1 then distribution is equally dispersed.</p><p>Evidence for clumped distribution of focal species.</p

Ecological similarity between species pairs along individual niche axes and the joint niche.

<p>¹Overall morphological similarity calculated from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134384#pone.0134384.t002" target="_blank">Table 2</a>, normalized values.</p><p>²Difference in preference for surface habitats, normalized values.</p><p>^{0.7, 0.8, 0.9} The values denote maximum Spearman’s rank correlation between BioClim variables allowed in calculation of Schoener’s D index. For calculations of the joint niche values of D index were standardized.</p><p>*A statistically significant difference in values of selected BioClim variables for the species pair.</p><p>Ecological similarity between species pairs along individual niche axes and the joint niche.</p

Distribution of focal species and the studied area (the Istrian Peninsula).

<p>The inset map indicates the geographic position of the study area within Europe. Species presence records were superimposed on a SRTM Shaded Relief (Central North) layer available from ESRI.</p

Species`differences in morphological traits related to feeding biology.

<p>*diagnostic character between <i>N</i>. <i>krameri</i> A and <i>N</i>. <i>krameri</i> B.</p><p>Species`differences in morphological traits related to feeding biology.</p

Epi-hypogean distribution of the studied species, corrected for geological basement.

<p>Epi-hypogean distribution of the studied species, corrected for geological basement.</p

Summary of all results.

<p>¹ Numbers rang species pairs according to the similarity of the species ecological niche: 1- little difference, 6—maximum differences.</p><p>² All species exhibit a clumped distribution (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134384#pone.0134384.t004" target="_blank">Table 4</a>).</p><p>Summary of all results.</p

Comparative study of acetylcholinesterase and glutathione S-transferase activities of closely related cave and surface <i>Asellus aquaticus</i> (Isopoda: Crustacea)

<div><p>The freshwater isopod crustacean <i>Asellus aquaticus</i> has recently been developed as an emerging invertebrate cave model for studying evolutionary and developmental biology. Mostly morphological and genetic differences between cave and surface <i>A</i>. <i>aquaticus</i> populations have been described up to now, while scarce data are available on other aspects, including physiology. The purpose of this study was to advance our understanding of the physiological differences between cave <i>A</i>. <i>aquaticus</i> and its surface-dwelling counterparts. We sampled two surface populations from the surface section of the sinking Pivka River (central Slovenia, Europe), i.e. locality Pivka Polje, and locality Planina Polje, and one cave population from the subterranean section of the sinking Pivka River, i.e. locality Planina Cave. Animals were sampled in spring, summer and autumn. We measured the activities of acetylcholinesterase (AChE) and glutathione S-transferase (GST) in individuals snap-frozen in the field immediately after collection. Acetylcholinesterase is likely related to animals’ locomotor activity, while GST activity is related to the metabolic activity of an organism. Our study shows significantly lower AChE and GST activities in the cave population in comparison to both surface <i>A</i>. <i>aquaticus</i> populations. This confirms the assumption that cave <i>A</i>. <i>aquaticus</i> have lower locomotor and metabolic activity than surface <i>A</i>. <i>aquaticus</i> in their respective natural environments. In surface <i>A</i>. <i>aquaticus</i> populations, seasonal fluctuations in GST activity were observed, while these were less pronounced in individuals from the more stable cave environment. On the other hand, AChE activity was generally season-independent in all populations. To our knowledge, this is the first study of its kind conducted in <i>A</i>. <i>aquaticus</i>. Our results show that among closely related cave and surface <i>A</i>. <i>aquaticus</i> populations also physiological differences are present besides the morphological and genetic. These findings contribute to a better understanding of the biology of <i>A</i>. <i>aquaticus</i> and cave crustaceans in general.</p></div

Water temperature and dissolved oxygen concentration at sampling localities.

<p>Water temperature and dissolved oxygen concentration at sampling localities.</p