Natural History of Model Organisms: The big potential of the small frog Eleutherodactylus coqui

The Puerto Rican coquí frog Eleutherodactylus coqui (E. coqui) is both a cultural icon and a species with an unusual natural history that has attracted attention from researchers in a number of different fields within biology. Unlike most frogs, the coquí frog skips the tadpole stage, which makes it of interest to developmental biologists. The frog is best known in Puerto Rico for its notoriously loud mating call, which has allowed researchers to study aspects of social behavior such as vocal communication and courtship, while the ability of coquí to colonize new habitats has been used to explore the biology of invasive species. This article reviews research on the natural history of E. coqui and opportunities for future research.

Fungi of the “Bark Side”

You may not pay much attention to fungi growing on the bark of trees in your neighborhood, but there are many fungal species that scientists know have joined the “bark side.” The fungi living on bark do many interesting and surprising things. For example, bark fungi may prowl the bark in search of resources or new habitats. Fungi create tiny versions of themselves, called spores, which can use “the force” (of nature, like blowing wind, or flowing water) to move from one place to another on the bark. In this article, we introduce the microscopic war waging on the bark of your neighborhood trees, and present some of the fungi warriors of the bark side. We describe how some fungal spores use the force to stalk the bark (and beyond) during storms and discuss why fungi-bark interactions are another important reason to preserve and protect our trees.

Proposals for improvement of Annex I of Directive 92/43/EEC: Sardinia

The ‘Habitats’ Directive (HD 92/43/EEC) is one of the primary legal tools aiming at conserving nature in Europe. Due to the complex iter to revise it, the habitats listed in the Annex I have been seldom updated after the HD adoption. Basing on already available information and expert knowledge, this paper presents a preliminary list of relevant habitats occurring in Sardinia, not yet considered and worth to be placed in the Annex I. Two new habitat proposals, one habitat new for Italy, and nine new subtypes of already existing HD habitats are here described. Most of the proposed new habitats and subtypes have a limited distribution range, due to the high number of narrow, often endangered, endemic species that characterize them. Being neglected, they are consequently poorly investigated, inconstantly monitored and unprotected. Thus, the main aim of this paper is to promote their conservation through implementation of HD and its interpretation manuals.

Proposals for improvement of Annex I of Directive 92/43/EEC: Central Italy

The main purpose of the 92/43/EEC Habitats Directive is to contribute to the conservation of biodiversity, understood as habitat types and species of the flora and fauna of the European Union. To achieve this goal, natural and semi-natural biodiversity as a whole must be recognized and included in its annexes. As for the conservation of biotopes, named habitat types, Italy is unfortunately lacking as it the Annex I does not include important ecosystems that are typical of its territory, rare for biogeographical reasons or threatened. Therefore, the opportunity to identify a first list of significant habitats for central Italy is discussed here. For each of the new proposed types (new habitats or new subtypes) a sheet has been prepared to highlight their salient characteristics. The new proposals concern seven habitat types and one subtype: sedge and reeds formations (Freshwater large sedge and reed beds), willow shrublands (Shrubby willow formations of river banks and fens), Apennine garrigues (Apennine hilly and montane garrigues), a new subtype of Annex I Habitat 6130 (Communities of herbaceous and dwarf shrub-suffrutescent plants of Italian ultramafic substrates), ancient olive groves ("Centuries-old olive groves" with evergreen Quercus spp. and arborescent matorral), secondary meadows (Italian submontane and montane pastured meadows dominated by Cynosurus cristatus), badlands (Pioneer halophilous and sub-halophilous communities of “calanchi” and “biancane” badlands) and hop-hornbeam woods (Italian-Balkan hop-hornbeam woods).

A NEW FINDING OF A RARE FUNGUS PISOLITHUS ARHIZUS (BOLETALES, BASIDIOMYCOTA) ON THE TERRITORY OF ODESA REGION

Problem. The distribution of species from the Red Book of Ukraine has been studied insufficiently. This also applies to the rare fungus Pisolithus arhizus (Scop.) Rauschert. Therefore, the discovery of new habitats of rare species is relevant. Aim. The aim of the work is to characterize the new locality of P. arhizus from Odesa region, found on September 12, 2021. Methods. The site was found during a survey of the coast of the Tyligul estuary by a route method. The determination of the fungus was carried out according to the Determinant of fungi of Ukraine. Results. A new locality of P. arhizus was discovered on the bank of the Tyligul estuary in the vicinity of the village of Liubopol, Lyman district, Odesa region. This finding complements the information on the mycobiota of the regional landscape park "Tyligulskyi" (Odesa region). One carpophore was found, the morphometric parameters of which were known in the literature. It is possible that Pisolithus arhizus is a symbiont of cultured Juniperus sabina L.

Food preference and food type innovation of surface- vs. cave-dwelling waterlouse (Asellus aquaticus) after 60 000 years of isolation

Behavioural innovativeness is important for colonising new habitats; however, it is also costly. Along the colonisation event of a simple, stable and isolated habitat offering only new food sources, one could hypothesize that the colonising individuals are more innovative than the average in their source population, showing preference to the new resource, while after colonisation, the adapted population will lose its innovativeness and become specialised to the new resource. To test this hypothesis, we compared food preference and food type innovation of a cave-dwelling waterlouse (Asellus aquaticus) population (genetically isolated for at least 60 000 years) to three surface-dwelling populations, also sampling individuals that have recently entered the cave (‘colonists’). In the cave, the only food sources are endogenous bacterial mats, while surface populations feed on various living and dead plant material together with their fungal and bacterial overgrow. We assayed all populations with the familiar and unfamiliar food types from the natural habitats and two novel food types not occurring in the natural habitats of the species. We found that all populations preferred surface to cave food and consumed the unnatural novel food types. Surface populations avoided cave food and colonists spent the most time with feeding on surface food. We conclude that the cave population maintained its preference for surface food and did not lose its food type innovativeness. We suggest that adapting to the special cave food was a major challenge in colonising the cave. Significance statement Behavioural innovativeness is a key trait for adapting to environmental changes or to colonise new habitats. However, it has developmental and maintenance costs due to the high energy need of the necessary sensory and neural organs. Therefore, we asked whether behavioural innovativeness decreases after colonising an isolated, stable and highly specialised habitat. By comparing food type innovativeness of surface-dwelling populations of waterlouse (Asellus aquaticus) to a population that has colonised a cave at least 60 000 years ago, we found that the high innovativeness towards unnatural food was retained in the cave population. Further, all populations preferred surface food (decaying leaves), with surface populations almost completely avoiding cave food (endogenous bacteria mats). We suggest that (i) food type innovativeness is evolutionary rigid in our system and (ii) the cave food was rather an obstacle against than a trigger of cave colonisation.

Phage co-transport with hyphal-riding bacteria fuels bacterial invasion in a water-unsaturated microbial model system

Nonmotile microorganisms often enter new habitats by co-transport with motile microorganisms. Here, we report that also lytic phages can co-transport with hyphal-riding bacteria and facilitate bacterial colonization of a new habitat. This is comparable to the concept of biological invasions in macroecology. In analogy to invasion frameworks in plant and animal ecology, we tailored spatially organized, water-unsaturated model microcosms using hyphae of Pythium ultimum as invasion paths and flagellated soil-bacterium Pseudomonas putida KT2440 as carrier for co-transport of Escherichia virus T4. P. putida KT2440 efficiently dispersed along P. ultimum to new habitats and dispatched T4 phages across air gaps transporting ≈0.6 phages bacteria−1. No T4 displacement along hyphae was observed in the absence of carrier bacteria. If E. coli occupied the new habitat, T4 co-transport fueled the fitness of invading P. putida KT2440, while the absence of phage co-transport led to poor colonization followed by extinction. Our data emphasize the importance of hyphal transport of bacteria and associated phages in regulating fitness and composition of microbial populations in water-unsaturated systems. As such co-transport seems analogous to macroecological invasion processes, hyphosphere systems with motile bacteria and co-transported phages could be useful models for testing hypotheses in invasion ecology.

Metabolic Response of Aphid Cinara tujafilina to Cold Stress

Climate changes enable thermophilic insect species to expand their ranges, but also force them to adapt to unfavourable environmental conditions in new habitats. Focusing on Cinara tujafilina, we investigated the metabolic changes in the body of the aphid that enabled it to survive the low temperatures of winter. Using GC–MS analysis, differences in the chemical composition of the aphids in summer and winter were found. The metabolic changes were mainly related to the increased activity of the pathways of carbohydrate metabolism, such as glycolysis and the pentose phosphate pathway; a decrease in tricarboxylic acid cycle (TCA); accumulation of polyols; and increased levels of proline, tyrosine, and fatty acids.

Global patterns and rates of habitat transitions across the eukaryotic tree of life

The successful colonisation of new habitats has played a fundamental role during the evolution of life. Salinity is one of the strongest barriers for organisms to cross, which has resulted in the evolution of distinct marine and terrestrial (including both freshwater and soil) communities. Although microbes represent by far the vast majority of eukaryote diversity, the role of the salt barrier in shaping the diversity across the eukaryotic tree is poorly known. Traditional views suggest rare and ancient marine-terrestrial transitions, but this view is being challenged by the discovery of several recently transitioned lineages. Here, we investigate habitat evolution across the tree of eukaryotes using a unique set of taxon-rich environmental phylogenies inferred from a combination of long-read and short-read metabarcoding data spanning the ribosomal DNA operon. Our results show that overall marine and terrestrial microbial communities are phylogenetically distinct, but transitions have occurred in both directions in almost all major eukaryotic lineages, with at least 350 transition events detected. Some groups have experienced relatively high rates of transitions, most notably fungi for which crossing the salt barrier has most likely been an important aspect of their successful diversification. At the deepest phylogenetic levels, ancestral habitat reconstruction analyses suggest that eukaryotes may have first evolved in non-saline habitats, and that the two largest known eukaryotic assemblages (TSAR and Amorphea) arose in different habitats. Overall, our findings indicate that crossing the salt barrier has played an important role in eukaryotic evolution by providing new ecological niches to fill.

Shaping the Ecotone Zone in Forest Communities That Are Adjacent to Expressway Roads

As a result of forest fragmentation, ecotones have become an important contribution to the landscape. The areas that include ecotones are constantly growing, thus creating new habitats for plants and animals. The factor that has the greatest impact on the configuration and extent of an ecotone is called the “edge effect”. The aim of this study was to determine the width of the ecotones in forests that are adjacent to an expressway and to characterize the edge effect they produced. The research was performed along ten transects situated at the edge of a forest and in the interior part of a forest (plots from 0 to 200 m). The structures of the forest stand, trees, shrubs, dwarf shrubs and herbs were determined and data on the species composition and species cover were also collected. Results of the statistical analyses (linear mixed models as well as detrended and canonical correspondence analyses) indicated significant changes in the structure, species composition, and species turnover that were dependent on the distance from the edge of the forest. It was shown that shrubs (cover, density, species richness) were the most affected while vascular plants were the least affected. However, the changes were ambiguous. There was either an increase or decrease in the individual parameters of the forest structure and the coverage of forest species. The extent of the forest edge began at a minimum distance of 0–20 m.