Hearing in Cavefishes

Caves and associated subterranean habitats represent some of the harshest environments on Earth, yet many organisms, including fishes, have colonized and thrive in these habitats despite the complete absence of light, and other abiotic and biotic constraints. Over 170 species of fishes are considered obligate subterranean inhabitants (stygobionts) that exhibit some degree of troglomorphy, including degeneration of eyes and reduction in pigmentation. To compensate for lack of vision, many species have evolved constructive changes to non-visual sensory modalities. In this chapter we review hearing in cavefishes, with particular emphasize on our own studies on amblyopsid cavefishes. Hearing in cavefishes has not been well studied to date, as hearing ability has only been examined in four species. Two species show no differences in hearing ability relative to their surface relatives, while the other two species (family Amblyopsidae) exhibit regression in the form of reduced hearing range and reduction in hair cell densities on sensory epithelia. In addition to reviewing our current knowledge on cavefish hearing, we offer suggestions for future avenues of research on cavefish hearing and discuss the influence of Popper and Fay on the field of cavefish bioacoustics

Molecular phylogeny of the blind cavefish Phreatichthys andruzzii and Garra barreimiae within the family Cyprinidae

The phylogenetic relationships of two cavefish, Phreatichthys andruzzii and Garra barreimiae, belonging to the family Cyprinidae, were investigated by sequencing the mitochondrial cytochrome b gene. These cavefish species are native to Somalia (eastern Africa) and Oman (southeastern Arabian peninsula), respectively, and so far no molecular support to their taxonomy and phylogenetic position was ever provided. The analysis of cytochrome b sequences showed that the species are monophyletic taxa, closely related to each other and to other species of the genus Garra. Molecular clock calculations allowed to date the origin of these hypogaean species back to the Plio-Pleistocene and support the hypothesis that African cyprinids originated from Miocenic immigrations of Asian ancestors

The invertebrate ecology of the Chalk aquifer in England (UK)

The Chalk is an important water supply aquifer, yet ecosystems within it remain poorly understood. Boreholes (198) in seven areas of England (UK) were sampled to determine the importance of the Chalk aquifer as a habitat, and to improve understanding of how species are distributed. Stygobitic macro-invertebrates were remarkably common, and were recorded in 67 % of boreholes in unconcealed Chalk, although they were not recorded in Chalk that is concealed by low-permeability strata and thus likely to be confined. Most species were found in shallow boreholes (50 m) water tables, indicating that the habitat is vertically extensive. Stygobites were present in more boreholes in southern England than northern England (77 % compared to 38 %). Only two species were found in northern England compared to six in southern England, but overall seven of the eight stygobitic macro-invertebrate species found in England were detected in the Chalk. Two species are common in southern England, but absent from northern England despite the presence of a continuous habitat prior to the Devensian glaciation. This suggests that either they did not survive glaciations in the north where glaciers were more extensive, or dispersal rates are slow and they have never colonised northern England. Subsurface ecosystems comprising aquatic macro-invertebrates and meiofauna, as well as the microbial organisms they interact with, are likely to be widespread in the Chalk aquifer. They represent an important contribution to biodiversity, and may influence biogeochemical cycles and provide other ecosystem services

Delimiting species by reproductive isolation : the genetic structure of epigean and hypogean Trichomycterus spp. (Teleostei, Siluriformes) in the restricted area of Torotoro (Upper Amazon, Bolivia)

Genetic variability of Trichomycterus from the region of Torotoro (Bolivia, Upper Amazon), distributed in the same watershed where the habitat is structured by waterfalls, canyons and a cave, was studied by allozyme (twelve putative loci) and RFLP-mtDNA (DLoop and cytochrome b) analyses. Alloenzymatic variation studied by Correspondence Analysis and Maximum Likelihood Analysis revealed a four-group structure, which was largely congruent with the distribution of the 14 mtDNA haplotypes. Two of these four clusters (I and II) were differentiated by two diagnostic loci (IDH and G3PDH), two semi-diagnostic loci (PGM and 6PGDH) and consequently a very high F-st value (estimator theta = 0.77). Therefore, clusters I and II are reproductively isolated. The distribution limit of these two (sibling) species does not correspond to those of the morphological species of Trichomycterus identified in this region: the epigean T. cf. barbouri and the hypogean T. chaberti. However, hypogean fish exhibited two mtDNA haplotypes, a private one and another shared with the epigean Trichomycterus from upstream reaches

Coordinating knowledge creation: A systematic literature review on the interplay between operational excellence and industry 4.0 technologies

In the process of creating new knowledge, literature has scarcely studied how bodies of knowledge arising from different sources should be coordinated to enhance performance. In particular, the present research focuses on two sources of newly created knowledge, i.e., operational excellence and Industry 4.0, to understand whether they should be implemented sequentially or simultaneously. Operational excellence refers to the implementation of practices such as just in time, total quality management, and Six Sigma that help a firm to create knowledge that facilitates waste reduction and customer value improvement. Industry 4.0 refers to the implementation of new technologies such as artificial intelligence, big data, robotics, Internet of Things, and laser cutting that help a firm to create knowledge to improve overall business performance. We identified and analyzed 30 papers published in 13 peer-reviewed journals and conference proceedings in the field of operations management. Our findings based on the systematic literature review suggest that the interplay between operational excellence and Industry 4.0 can be categorized into four groups: (1) Industry 4.0 supports operational excellence; (2) operational excellence supports Industry 4.0; (3) complementary; and (4) no interdependence. Majority of the papers under study are in the first category, suggesting Industry 4.0 technologies as enabler of operational excellence