While extensive research on traditional model species has significantly advanced the biological sciences, the ongoing search for new model organisms is essential to tackle contemporary challenges ...such as human diseases or climate change, and fundamental phenomena including adaptation or speciation. Recent methodological advances such as next-generation sequencing, gene editing, and imaging are widely applicable and have simplified the selection of species with specific traits from the wild. However, a critical milestone in this endeavor remains the successful cultivation of selected species. A historically overlooked but increasingly recognized group of non-model organisms are cave dwellers. These unique animals offer invaluable insights into the genetic basis of human diseases like eye degeneration, metabolic and neurological disorders, and basic evolutionary principles and the origin of adaptive phenotypes. However, to take advantage of the beneficial traits of cave-dwelling animals, laboratory cultures must be established-a practice that remains extremely rare except for the cavefish Astyanax mexicanus. For most cave-dwelling organisms, there are no published culturing protocols. In this study, we present the results of our multi-year effort to establish laboratory cultures for a variety of invertebrate groups. We have developed comprehensive protocols for housing, feeding, and husbandry of cave dwellers and their surface relatives. Our recommendations are versatile and can be applied to a wide range of species. Hopefully our efforts will facilitate the establishment of new laboratory animal facilities for cave-dwelling organisms and encourage their greater use in experimental biology.
Isopods are a diverse group of crustaceans, that inhabit various environments, including terrestrial, freshwater, and marine, both on the surface and in the underground. The biological mechanisms ...underlying their wide range of adaptations to diverse ecological niches remain elusive. In order to unravel the molecular basis of their adaptability, we generated a comprehensive RNAseq dataset comprising 11 isopod species belonging to the three different suborders: freshwater Asellota, marine, brackish and freshwater Sphaeromatidea, and terrestrial Oniscidea, with representatives from families Asellidae, Sphaeromatidae, and Trichoniscidae, respectively. Representatives of each family were collected from both cave and surface environments, representing at least three independent cave colonization events. Three biological replicates were sequenced from each species to ensure data robustness. The 11 high-quality RNAseq datasets will serve as a valuable resource for understanding cave-specific adaptations, comparative and functional genomics, ecological annotation as well as aid in conservation efforts of these non-model organisms. Importantly, transcriptomes of eight featured species have been made publicly accessible for the first time.
The Dinaric Karst is a global hotspot for subterranean diversity, with two distinct peaks of species richness in the northwest and southeast, and an area of a lower species richness in the central ...part. In this article, we present a species list and describe the ecological conditions of the Lukina jama–Trojama cave system, located in the central part of the Dinaric Karst. This cave system is the deepest and one of the most logistically challenging cave systems sampled so far in the Dinaric Karst. Repeated sampling resulted in a list of 45 species, including 25 troglobionts, 3 troglophiles, 16 stygobionts, and 1 stygophile. Most of the recorded species are endemic to the Velebit Mountain, while three species are endemic to the Lukina jama–Trojama cave system. Within the system, species richness peaks in the deepest third of the cave, most likely reflecting the harsh ecological conditions in the upper parts, including ice, cold winds, and occasional waterfalls. Milder and more stable deeper parts of the cave contain a rich subterranean species community, part of which is associated with two very distinct aquatic habitats, the cave hygropetric and the phreatic zone. The newly recognized hotspot of subterranean biodiversity in the central Dinaric Karst, which has emerged between the two known centers of biodiversity, further highlights the species richness in large cave systems, but also challenges the diversity patterns in the Dinaric Karst overall.
In the Dinaric Karst, Alpioniscus (Illyrionethes) is the taxon with the largest number of troglobiotic species (19), one of which is new and described here:
A. busljetai
sp. nov.
, found in two caves ...in the coastal area of North Dalmatia. Both caves are threatened by human activities (IUCN threats 1.1, 9.1.1).
Terrestrial isopods were studied in the Dubravica peat bog and surrounding forest in the northwestern Croatia. Sampling was conducted using pitfall traps over a two year period. Studied peat bog has ...a history of drastically decrease in area during the last five decades mainly due to the process of natural succession and changes in the water level. A total of 389 isopod individuals belonging to 8 species were captured. Species richness did not significantly differ between bog, edge and surrounding forest. High species richness at the bog is most likely the result of progressive vegetation succession, small size of the bog and interspecific relationships, such as predation. With spreading of Molinia grass on the peat bog, upper layers of Sphagnum mosses become less humid and probably more suitable for forest species that slowly colonise bog area. The highest diversity was found at the edge mainly due to the edge effect and seasonal immigration, but also possibly due to high abundance and predator pressure of the Myrmica ants and lycosid spiders at the bog site. The most abundant species were Trachelipus rathkii and Protracheoniscus politus, in the bog area and in the forest, respectively. Bog specific species were not recorded and the majority of the species collected belong to the group of tyrphoneutral species. However, Hyloniscus adonis could be considered as a tyrphoxenous species regarding its habitat preferences. Most of collected isopod species are widespread eurytopic species that usually inhabit various habitats and therefore indicate negative successive changes or degradation processes in the peat bog.
Darkness is the hallmark of all subterranean habitats and, to some degree, of many surface habitats. Many surface animals that live in semi-dark habitats, such as freshwater benthos, are photophobic. ...Yet, few of them can colonize caves and form subterranean populations. We hypothesize that phenotypic plasticity induced by darkness enables surface crustaceans to colonize caves, as has been previously shown for the cavefish
Astyanax mexicanus
.
Our target organisms were surface species that form distinct subterranean populations with different adaptations to caves and have closely related cave species.
Proasellus
proved to be a good model system, and we selected the surface species
Proasellus coxalis
and its cave relative
P. anophtalmus
to learn what adaptations evolve in subterranean forms. We exposed a randomly selected group of both species to complete darkness (DD) where we could establish breeding colonies. Control breeding colonies are exposed to a 12:12 h light-dark photoperiod (LD). Other conditions are kept as constant and equal as possible, including conditioned
Alnus glutinosa
leaves used for shelter and food.
We examined the molecular phenotypes of both
Proasellus
species, animals originally collected from the wild and preserved after four months under the experimental conditions DD and LD. The number of observed differentially expressed genes (DEGs) was significantly higher between cohorts DD and LD of
P. coxalis
compared to
P. anophtalmus
. The direction of regulation of DEGs also showed the opposite effect, with the cohort of
P. coxalis
DD showing predominant upregulation and the cohort of
P. anophtalmus
DD showing predominant downregulation relative to their cohorts LD. A greater number of DEGs in both species were associated with various metabolic processes such as lipid regulation. In contrast, DEGs related to growth, cell division, rhythmic processes, sensory perception of taste, and sexual reproduction were observed only in
P. coxalis
.
We examined the changes at the phenotypic level in the first generation born in the experiment. Surprisingly,
P. coxalis
showed better fitness under DD conditions (growth rate, fecundity, survival). Other phenotypes were altered in both adaptive and non-adaptive directions i. e. towards vs. opposite of cave adaptations. We conclude that darkness is not a limiting factor in cave colonization and suggest that it may even be a key factor in the evolution of troglomorphy via phenotypic plasticity.
Abstract
Species richness of terrestrial isopods is high in caves of the Dinaric Karst, which hosts ~10% of the world’s nominal oniscidean troglobionts. The most widespread taxon is the southern ...European genus Alpioniscus, which consists of two subgenera: Alpioniscus s.s. and Illyrionethes. Before this study, 14 nominal troglobiotic Illyrionethes taxa were recorded from the Dinaric Karst. Our molecular analyses using two mitochnodrial DNA (16S rRNA and COI) fragments and a nuclear gene (H3) fragment on all known Dinaric taxa identified three distinct lineages: strasseri-, heroldi- and magnus-lineage. Our results confirmed the validity of most nominal species. The exceptions are Alpioniscus balthasari, which consists of two different species including Alpioniscus iapodicus, and Alpioniscus heroldi, which is paraphyletic with respect to Alpioniscus bosniensis. The strasseri-lineage was highly supported by all phylogenetic methods used; therefore, we performed a detailed morphological analysis to distinguish and characterize the species of this group. New morphological characters, such as body part ratios, are proposed for future species identification. In addition, we redescribe three known species (Alpioniscus strasseri, Alpioniscus christiani and Alpioniscus balthasari) and describe two new ones (Alpioniscus hirci sp. nov. and Alpioniscus velebiticus sp. nov.). As a result, 15 nominal species of Illyrionethes are currently known from the Dinaric Karst.
A new species of Alpioniscus Bedek, Jana; Gottstein, Sanja; Taiti, Stefano
Subterranean biology,
09/2019
3
Journal Article
Recenzirano
In the Dinaric Karst, Alpioniscus (Illyrionethes) is the taxon with the largest number of troglobiotic species (19), one of which is new and described here: A. busljetai sp. nov., found in two caves ...in the coastal area of North Dalmatia. Both caves are threatened by human activities (IUCN threats 1.1, 9.1.1).
Biology Students Association – BIUS (BIUS) from Zagreb, Croatia is a non-government and non-profit association founded in 1999 by biology students from the Faculty of Science, University of Zagreb. ...Aiming to develop future experts in different fields of biology, BIUS is composed of groups that specialize in various subject areas. Besides holding diverse science lectures, workshops, and field trips, the main BIUS' activities are annual student research camps with the participation of up to 130 members.
An integral part of BIUS from the very beginning is the Biospeleology group (Group). During these first 23 years of the Group's existence, many members discovered their interest in cave biology through field research, cabinet work, and educational workshops. The Group organized two student research camps and participated in 16 others. In addition, the Group organized seven independent projects. Throughout all of these projects, cave fauna was collected from over 150 caves and pits at different localities of Croatian karst. The Group's long-term existence is facilitated by the guidance of mentors from the Croatian Biospeleological Society. Altogether, the Group provides numerous skills and valuable opportunities to students and is important for developing future scientific experts in cave biology in Croatia.
So far, 12 Group members have written their master thesis and four have their doctoral thesis in the field of cave biology. Former members currently work at universities, research institutes, government, and civil sector, or as entrepreneurs on topics closely related to cave biology and karst research.
•The terrestrial isopod community in the fen was impoverished due to the high water table, which suppressed colonization from adjacent habitats.•The exception was Ligidium germanicum, which ...maintained stable populations in the fen.•Successional changes promoted higher isopod activity density due to the lower water table and higher vegetation complexity compared to the fen.•Preservation of hydrological conditions in the fen is essential for suppressing colonization of forest and generalist species.
Peatlands in the Western Balkans are becoming rapidly reduced due to vegetation succession, further enhanced by climate change and abandonment of traditional land management practices. Currently, the peatlands of this region act as habitat islands embedded mainly in a forest landscape matrix. This allows them to host more forest and generalist species of animals and plants than would be expected from such ecosystem. We were interested in testing if a taxon, unspecialized for such extreme habitats, can maintain stable populations in a peatland, and how environmental fluctuations affect its spatio-temporal distributions along a successional gradient. Terrestrial isopods were sampled in four habitat types: a fen, two successional habitats and a beech forest, with pitfall traps during two consecutive years. In total, 1069 individuals belonging to five species were recorded. Activity density increased more than four-fold along the successional gradient, from the fen to an older and more complex successional habitat. This pattern was governed by an increase in the structural complexity of the habitat, where succession habitats supported more favourable shelter sites for terrestrial isopods. Soil moisture decreased over 30% along the successional gradient. Additionally, the older successional habitat was more nutrient rich than the fen, providing higher substrate quality for decomposers and enabling the survival of forest species. The fen was inhabited by a single species, Ligidium germanicum, while other species were extremely rare. Its seasonal activity started in the spring, reaching the maximum in June and decreasing at the end of summer. Spatial changes in isopod assemblages along the successional gradient imply that the groundwater level in the fen was sufficiently high to supress the invasion of forest species into the fen. Colonisation of the fen by terrestrial isopods will likely progress as environmental conditions become more suitable by progressive vegetation succession and climate change.
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