Phylogenetics and biogeography of the Balkan ‘sand gobies’ (Teleostei: Gobiidae): vulnerable species in need of taxonomic revision

Within the Atlantic–Mediterranean region, the ‘sand gobies’ are abundant and widespread, and play an important role in marine, brackish, and freshwater ecosystems. They include the smallest European freshwater fish, Economidichthys trichonis, which is threatened by habitat loss and pollution, as are several other sand gobies. Key to good conservation management is an accurate account of the number of evolutionary significant units. Nevertheless, many taxonomic and evolutionary questions remain unresolved within the clade, and molecular studies are lacking, especially in the Balkans. Using partial 12S and 16S mitochondrial ribosomal DNA sequences of 96 specimens of at least eight nominal species (both freshwater and marine populations), we assess species relationships and compare molecular and morphological data. The results obtained do not support the monophyly of Economidichthys, suggesting the perianal organ to be a shared adaptation to hole‐brooding rather than a synapomorphy, and urge for a taxonomic revision of Knipowitschia. The recently described Knipowitschia montenegrina seems to belong to a separate South‐East Adriatic lineage. Knipowitschia milleri, an alleged endemic of the Acheron River, and Knipowitschia cf. panizzae, are shown to be very closely related to other western Greek Knipowitschia populations, and appear conspecific. A distinct Macedonian–Thessalian lineage is formed by Knipowitschia thessala, whereas Knipowitschia caucasica appears as an eastern lineage, with populations in Thrace and the Aegean. The present study combines the phylogeny of a goby radiation with insights on the historical biogeography of the eastern Mediterranean, and identifies evolutionary units meriting conservation attention. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 73–91.     

Region‐wide temporal and spatial variation in Caribbean reef architecture: is coral cover the whole story?

The architectural complexity of coral reefs is largely generated by reef‐building corals, yet the effects of current regional‐scale declines in coral cover on reef complexity are poorly understood. In particular, both the extent to which declines in coral cover lead to declines in complexity and the length of time it takes for reefs to collapse following coral mortality are unknown. Here we assess the extent of temporal and spatial covariation between coral cover and reef architectural complexity using a Caribbean‐wide dataset of temporally replicated estimates spanning four decades. Both coral cover and architectural complexity have declined rapidly over time, with little evidence of a time‐lag. However, annual rates of change in coral cover and complexity do not covary, and levels of complexity vary greatly among reefs with similar coral cover. These findings suggest that the stressors influencing Caribbean reefs are sufficiently severe and widespread to produce similar regional‐scale declines in coral cover and reef complexity, even though reef architectural complexity is not a direct function of coral cover at local scales. Given that architectural complexity is not a simple function of coral cover, it is important that conservation monitoring and restoration give due consideration to both architecture and coral cover. This will help ensure that the ecosystem services supported by architectural complexity, such as nutrient recycling, dissipation of wave energy, fish production and diversity, are maintained and enhanced.     

AFM IMAGING AND ELASTICITY MEASUREMENTS ON LIVING RAT LIVER MACROPHAGES

The authors investigated the morphology and the elastic properties of living cultured rat liver macrophages (Kupffer cells) with an atomic force microscope (AFM). Continuous imaging and elasticity mapping of individual cells in physiological buffer was carried out for several hours without damaging the cells as judged by their persistent undisturbed morphology. Dynamic events such as protrusive activity were observed in time course. The importance of the cytoskeleton for the mechanical properties of the cell has been investigated by measuring the cell's elasticity as a function of position. Chemical disassembly of the actin network by applying 10μg/ml cytochalasin B decreased the cell's average elastic modulus seven-fold within less than 40 minutes. Treating the cells with 0.1μg/ml latrunculin A resulted in a two-fold decrease in the elastic modulus merely in the perinuclear region after 40 minutes, whereas other parts of the cell were not affected.