Caves offer some of the best known examples for evolutionary replications where similar morphologies evolve independently as the result of strong natural selection of the extreme environment. We compared the degree of evolutionary change between a cave population from a Slovenian sinking river and Romanian sulfidic caves. Genetic analyses showed that the same study species, Asellus aquaticus, invaded both caves independently. The overall morphology of the new cave populations has changed dramatically compared to the ancestral surface population (50 of 62 morphometric traits). However, only 18 traits changed in a parallel fashion, including eye and pigment loss and antennal elongation. These traits are the most likely candidates for common cave-related adaptations, whereas the remaining two thirds could be adaptations to different ecological aspects of both caves, or traits drifting under relaxed selection. Our results suggest that divergent evolution can be important in caves, although it is often masked by very obvious common changes like eye loss and depigmentation.
COBISS.SI-ID: 3362127
We performed a cytogenetic analysis of the European blind cave salamander, Proteus anguinus, and compared our results to what is known about its closest relative, the North American genus Necturus. All species of Necturus have strongly heteromorphic X-Y sex chromosomes in which the Y chromosome is much smaller than the X and has a distinct pattern of heterochromatic C-bands. We have discovered that Proteus has evolved a unique genetic feature in which a Necturus-like Y chromosome has become translocated to the X chromosome, so that all animals, both male and female, have a pair of combined (or “chimeric”) X-Y chromosomes. We found this translocation in three genetically isolated populations in Slovenia, including both the »white« proteus (P. a. anguinus) and the »black« proteus (P. a. parkelj). The X-Y sex chromosome translocation is associated with a relatively high incidence of reproductive peculiarities, including testes containing developing eggs (“testis-ova”) and even hermaphrodites. We hypothesize that these reproductive peculiarities are consequences of interactions among sex-determining genes on the fused chromosomes, disrupting normal sex differentiation in some individuals, just as seen in clinical cases. Our goal is to try to understand the evolutionary signficance of the X-Y translocation in Proteus. We think that the chromosome translocation affects genes that are involved in certain cave adaptations that are critical for its survival in the harsh cave environment. Our current research is focused on testing this hypothesis.
COBISS.SI-ID: 3936079
Particle specific effects on organisms are one of the main questions ever since the beginning of nanoecotoxicology research. Indeed, literature data provide very few direct proofs that this may be true. The majority of studies indicate that in the case of metal nanoparticles the metal ions are the main inducers of effects. The main reason for this lies in the lack of appropriate methods used to observe the changes and also the exposure doses are unrealistically high. In this study, we have exposed the terrestrial isopods to very low doses of nanoparticles and the subcellular changes were tracked using a Fourier transform infrared spectroscopy. We proved that zinc oxide nanoparticles induce particle specific effects on digestive glands of isopods. This finding is very important for future nanosafety research.
COBISS.SI-ID: 3553103
Skeletal elements that are exposed to heavy mechanical loads may provide important insights into the evolutionary solutions to mechanical challenges. We analyzed the microscopic architecture of dactylus claws in the woodlice Porcellio scaber and correlated these observations with analyses of the claws’ mineral composition with energy dispersive X-ray spectrometry (EDX), electron energy loss spectroscopy (EELS) and selected area electron diffraction (SAED). Extraordinarily, amorphous calcium phosphate is the predominant mineral in the claw endocuticle. Unlike the strongly calcified exocuticle of the dactylus base, the claw exocuticle is devoid of mineral and is highly brominated. The architecture of the dactylus claw cuticle is drastically different from that of other parts of the exoskeleton. In contrast to the quasi-isotropic structure with chitin-protein fibers oriented in multiple directions, characteristic of the arthropod exoskeleton, the chitin-protein fibers and mineral components in the endocuticle of P. scaber claws are exclusively axially oriented. Taken together, these characteristics suggest that the claw cuticle is highly structurally anisotropic and fracture resistant and can be explained as adaptations to predominant axial loading of the thin, elongated claws. The nanoscale architecture of the isopod claw may inspire technological solutions in the design of durable machine elements subjected to heavy loading and wear.
COBISS.SI-ID: 3927887
The ongoing refugee crisis in Europe has seen many countries rush to construct border security fencing to divert or control the flow of people. This follows a trend of border fence construction across Eurasia during the post-9/11 era. This development has gone largely unnoticed by conservation biologists during an era in which, ironically, transboundary cooperation has emerged as a conservation paradigm. These fences represent a major threat to wildlife because they can cause mortality, obstruct access to seasonally important resources, and reduce effective population size. We summarise the extent of the issue and propose concrete mitigation measures.
COBISS.SI-ID: 3923279