Cryptic invertebrates on subtidal rocky reefs vary with microhabitat structure and protection from fishing

The deployment of flat concrete blocks on subtidal rocky reefs can replicate natural reef microhabitats and provides a means for standardized sampling of cryptic invertebrates. The shape of the cavity beneath the block is related to reef topography and may influence the invertebrate community by affecting the amount of space for cryptic fauna to colonise and influencing the effectiveness of their predator-defence mechanisms. To determine the effect of sub-block reef structure and different levels of external predators on cryptic molluscs and echinoderms, I deployed concrete blocks at locations inside and outside the Maria Island marine reserve in eastern Tasmania, Australia. Relationships between sub-block reef structure and the cryptic invertebrate assemblage were evident between locations, whereas only a small but significant proportion of variation of assemblages between blocks within location was explained by reef surface area. No clear association with external predation pressure was evident in multivariate analyses of variation in assemblage structure. Juvenile abalone Haliotis rubra were not influenced by micro-habitat structure but were significantly less abundant at protected locations, the only species to exhibit such a response. This result follows a decline of emergent adult abalone in the marine reserve and raises the possibility of recruitment failure of abalone at some fully protected locations in the longer term.

Phylogenetic analysis of receptor FgfrL1 shows divergence of the C-terminal end in rodents

FGFRL1 is a member of the fibroblast growth factor receptor (FGFR) family. Similar to the classical receptors FGFR1-FGFR4, it contains three extracellular Ig-like domains and a single transmembrane domain. However, it lacks the intracellular tyrosine kinase domain that would be required for signal transduction, but instead contains a short intracellular tail with a peculiar histidine-rich motif. This motif has been conserved during evolution from mollusks to echinoderms and vertebrates. Only the sequences of FgfrL1 from a few rodents diverge at the C-terminal region from the canonical sequence, as they appear to have suffered a frameshift mutation within the histidine-rich motif. This mutation is observed in mouse, rat and hamster, but not in the closely related rodents mole rat (Nannospalax) and jerboa (Jaculus), suggesting that it has occurred after branching of the Muridae and Cricetidae from the Dipodidae and Spalacidae. The consequence of the frameshift is a deletion of a few histidine residues and an extension of the C-terminus by about 40 unrelated amino acids. A similar frameshift mutation has also been observed in a human patient with a craniosynostosis syndrome as well as in several patients with colorectal cancer and bladder tumors, suggesting that the histidine-rich motif is prone to mutation. The reason why this motif was conserved during evolution in most species, but not in mice, is not clear.