That the ties between any obligate subterranean species and the hypogean environment depend on the interplay of a species' own physiological characteristics and all of the ecological characteristics ...of the adjacent epigean habitat(s), including biotic factors, has been emphasized. The reasons why troglomorphy cannot be included within criteria for classifying cave dwellers have been demonstrated. After a review of historic classifications, standardized definitions of the most widely used terms are proposed. The most easily recognized are four categories which are terminological approximations of the classic Schiner-Racovitza terminology: (1) troglobiont is a species or population, strictly bound to a hypogean habitat; (2) eutroglophile is an essentially epigean species, but able to maintain a permanent subterranean population; (3) subtroglophile is inclined perpetually or temporarily to inhabit a subterranean habitat but is bound to the surface for some biological functions (e.g. feeding); (4) trogloxene is a species only occurring sporadically underground.
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Leeches (Hirudinea) constitute a relatively small monophyletic group of highly specialized annelids, but may play important roles as invertebrate predators in freshwater, while others are infamous ...for their ectoparasitic bloodsucking. About 15% of the 680 described species are marine and slightly less have switched to terrestrial life; the rest are freshwater, divided among 91 genera. They are globally distributed on all continents except Antarctica, reaching the highest diversity in the Holarctic region with one-half of all continental species. Known areas of local endemism are the ancient Siberian lake Bajkal and lake Ohrid (about 10 species each) on the Balkan Peninsula, which is an endemicity area in itself. A small number of sanguivorous species known as “medicinal leeches” have played an important role in traditional and modern medicine, most noticeably four Hirudo spp. from the Western Palearctic.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Current theory predicts that a shift to a new habitat would increase the rate of diversification, while as lineages evolve into multiple species, intensified competition would decrease the rate of ...diversification. We used Holarctic amphipods of the genus Gammarus to test this hypothesis. We sequenced four genes (5,088 bp) for 289 samples representing 115 Gammarus species. A phylogenetic analysis showed that Gammarus originated from the Tethyan region with a saline ancestry in the Paleocene, and later colonized the freshwater habitat in the Middle Eocene. Ancestral range reconstruction and diversification mode analysis combined with paleogeological and paleoclimatic evidence suggested that the habitat shift from saline to freshwater led to an increased diversification rate. The saline lineage of Gammarus dispersed to both sides of the Atlantic at 55 million years ago (Ma), because of the few barriers between the Tethys and the Atlantic, and diversified throughout its evolutionary history with a constant diversification rate 0.04 species per million years (sp/My). The freshwater Gammarus, however, underwent a rapid diversification phase (0.11 sp/My) until the Middle Miocene, and lineages successively diversified across Eurasia via vicariance process likely driven by changes of the Tethys and landmass. In particular, the freshwater Gammarus lacustris and Gammarus balcanicus lineages had a relatively high diversification shift, corresponding to the regression of the Paratethys Sea and the continentalization of Eurasian lands during the Miocene period. Subsequently (14 Ma), the diversification rate of the freshwater Gammarus decreased to 0.05 and again to 0.01 sp/My. The genus Gammarus provides an excellent aquatic case supporting the hypothesis that ecological opportunities promote diversification.
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This study determines oxygen consumption (R), electron transport system (ETS) activity and R/ETS ratio in two pairs of epigean and hypogean crustacean species or subspecies. To date, metabolic ...characteristics among the phylogenetic distant epigean and hypogean species (i.e., species of different genera) or the epigean and hypogean populations of the same species have been studied due to little opportunity to compare closely related epigean and hypogean species. To fill this gap, we studied the epigean Niphargus zagrebensis and its troglobiotic relative Niphargus stygius, and the epigean subspecies Asellus aquaticus carniolicus in comparison to the troglobiotic subspecies Asellus aquaticus cavernicolus. We tested the previous findings of different metabolic rates obtained on less-appropriate pairs of species and provide additional information on thermal characteristics of metabolic enzymes in both species or subspecies types. Measurements were done at four temperatures. The values of studied traits, i.e., oxygen consumption, ETS activity, and ratio R/ETS, did not differ significantly between species or subspecies of the same genus from epigean and hypogean habitats, but they responded differently to temperature changes. Higher Q10-values for oxygen consumption of N. stygius than N. zagrebensis in the temperature range 10-20C and higher Ea indicated higher thermal sensitivity in the subterranean species. On the other hand, lower Q10 and Ea-values for ETS activity of N. stygius than N. zagrebensis indicated more thermally stable enzymatic machinery in N. stygius than N. zagrebensis. In Asellus, we observed a similar trend of lower Ea for oxygen consumption and higher Ea for ETS activity in epigean than the troglomorphic subspecies, but the values did not differ significantly between the two. Our most important conclusion is that the low metabolic rate is not a universal property of troglobiotic animals, and the degree of metabolic adaptation is not necessarily in agreement with the degree of morphological adaptation (troglomorphy).
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Ecological performance of animals depends on physiological and biochemical processes that are adjusted to the environment. The responses to hypoxia or anoxia have been frequently studied in ...subterranean aquatic organisms in order to find potential adaptations to restrict oxygen conditions occurring in the underground habitats. However, some previous studies have compared phylogenetic distant epigean and hypogean species or the epigean and hypogean populations of the same species due to little chance to compare closely related epigean and hypogean species. Therefore, in this study, we compared the effects of exposure to hypoxia, followed by reoxygenation, and increased temperature on oxygen consumption, potential metabolic activity, and antioxidant activities in closely related epigean and hypogean species:
Niphargus zagrebensis
and
N. stygius
. Oxygen consumption of
N. stygius
increased similarly during post-hypoxic recovery at 10 and 20°C (approx. 5-times), while
N. zagrebensis
increased its oxygen consumption for 9.7 and 4.4-times at 10 and 20°C, respectively. We observed higher exploitation of metabolic potential for current oxygen consumption during reoxygenation in
N. zagrebensis
than
N. stygius
. Exposure to hypoxia and subsequent reoxygenation at 20°C increased catalase (CAT) activity in
N. stygius
, but not in
N. zagrebensis.
We observed increased glutathione reductase activity in both
Niphargus
species. We concluded that respiratory and antioxidant responses to severe hypoxia and increased temperature differed between closely related epigean and hypogean
Niphargus
species. Hypogean
Niphargus
species possess physiological and biochemical characteristics that are advantageous in temperature stable subterranean environments which support inhabiting of species that have low energetic demands, while epigean
Niphargus
species can successfully inhabit specific surface habitats.
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It is known that electron donating groups have quite a different effect on the π-delocalization of a conjugate system when bonded at ortho and para as compared to meta positions in the phenyl ring. ...In the present work, the BF2 complex of 1-phenyl-3-(3,5-dimethoxyphenyl)-propane-1,3-dione (1), a molecule with two methoxy groups in one of the phenyl rings at meta positions, was prepared. Compound 1 exists as two polymorphs having different mutual orientations of the two methoxy groups: in polymorph A away from each other (termed anti), while in polymorph B one methoxy group is oriented toward the other (syn–anti). In both crystals, the molecules which are antiparallel (the subPh rings as well as dioxaborine are on opposite sides) form stacks through face-to-face π–π interactions, while in polymorph A the crystal packing is further stabilized by intermolecular C(phenyl)–H···F and C(methoxy)–H···F hydrogen bonds. Solid A possesses numerous chromic effects, including mechano-, thermo-, and chronochromism, though the latter to a lesser extent, as well as the effect of rearrangement of the amorphous phase into a more stable crystalline phase A, associated with crystallization-induced emission enhancement (CIEE). The solid-state emission can be repeatedly switched regarding its color and efficiency with excellent reversibility by external stimuli. On the other hand, crystalline solid B undergoes thermal interconversion of syn–anti to the anti conformer. Compound 1 shows a solvatochromic effect (SE), is aggregation-induced emission (AIE) active, and through the sublimation process displays self-assembling crystalline platelike microstructures or microfibers that reveal an obvious optical waveguide effect.
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1. Various groundwater habitats have exceptionally high levels of endemism caused by strong hydrographical isolation and low dispersal abilities of their inhabitants. More than 10% of ...macro-stygobiotic species nevertheless occupy relatively large ranges, measuring from some hundred to over 2000 km in length. These species represent a challenge because their distributions disregard hydrographical boundaries, and their means to disperse and maintain long-term gene flow are unknown. 2. Based on mitochondrial and nuclear gene sequences, we examined the phylogeographic structure of six formally recognised stygobiotic species (Niphargus virei, N. rhenorhodanensis, Troglocaris anophthalmus, T. hercegovinensis, Spelaeocaris pretneri, Proteus anguinus) and searched for cryptic lineage diversity in a genus-wide phylogeny of Niphargus. Using tree-based criteria as well as comparative divergence measures, we identified cryptic lineages, which may tentatively be equated with cryptic species. 3. Fourteen analysed nominal stygobiotic species with large ranges emerged as highly diversified, splitting into 51 tentative cryptic lineages. The degree of divergence was within the range or larger than the divergence of other related pairs of sister species. A substantial part (94%) of the cryptic lineages had ranges <200 km in length. One half of them were recorded at single sites only. The largest range recorded was that of a cryptic N. virei lineage (700 km), while none of the very large traditional ranges (e.g. Niphargus aquilex- 2300 km, N. tauri- 1900 km) could be corroborated. 4. These data suggest that small ranges of macro-stygobionts are the rule, and ranges over 200 km are extremely rare. 5. The implications of this result for groundwater biodiversity assessment and conservation include a considerable increase in overall diversity at the regional and continental scale and a strong decrease in faunal similarities among regions, coupled with greater endemism.
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The present study explores the utility of mitochondrial COI gene sequences to reveal phylogenetic and phylogeographic relationships for the entire European freshwater crayfish genus
Austropotamobius. ...The two traditional taxa,
Austropotamobius pallipes and
Austropotamobius torrentium, were monophyletic, showing similar genetic diversity, with 28 and 25 haplotypes, respectively, and an uncorrected average pairwise divergence of 0.059 and 0.041. A third distinct haplotype clade, in sister relation to
A. torrentium, was discovered at the Upper Kolpa drainage in the northern Dinaric area. All populations north and west of the Alps are genetically impoverished (nucleotide diversity (
π)
=
0.000–0.001), while southern populations are more diverse (
π
=
0.001–0.034).
A. pallipes reaches the highest diversity in the region of Istra, probably its primary center of radiation. The genetic diversity center for
A. torrentium is the southern Balkan peninsula. Other potential glacial refugia were identified in Southern France, Northwestern Italy, the Apennine Peninsula, and in the northern Dinaric area. The Iberian Peninsula has been stocked artificially from Northern Italy. Three main periods of radiation were tentatively identified: late Miocene/early Pliocene for the divergence of species and main lineages, the Pleistocene for the divergence within populations south from Alps, and a postPleistocene expansion north and west from Alps.
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