Evolution of digestive enzyme genes associated with dietary diversity of crabs.

Crabs feed on a wide range of items and display diverse feeding strategies. The primary objective of this study was to investigate 10 digestive enzyme genes in representative crabs to provide insights into the genetic basis of feeding habits among crab functional groups. Crabs were classified into three groups based on their feeding habits: herbivores (HV), omnivores (OV), and carnivores (CV). To test whether crabs' feeding adaptations matched adaptive evolution of digestive enzyme genes, we examined the 10 digestive enzyme genes of 12 crab species based on hepatopancreas transcriptome data. Each of the digestive enzyme genes was compared to orthologous sequences using both nucleotide- (i.e., PAML and Datamonkey) and protein-level (i.e., TreeSAAP) approaches. Positive selection genes were detected in HV crabs (AMYA, APN, and MGAM) and CV crabs (APN, CPB, PNLIP, RISC, TRY, and XPD). Additionally, a series of positive selection sites were localized in important functional regions of these digestive enzyme genes. This is the first study to characterize the molecular basis of crabs' digestive enzyme genes based on functional feeding group. Our data suggest that HV crabs have evolved an enhanced digestion capacity for carbohydrates, and CV crabs have acquired digestion capacity for proteins and lipids.

Cladorhiza corallophila sp. nov., a new carnivorous sponge (Cladorhizidae, Demospongiae) living in close association with Lophelia pertusa and Madrepora oculata (Scleractinia).

In this study, we describe a new species of cladorhizid sponge, which shows a very peculiar mode of life: It always occurs in association with the scleractinian cold-water corals Lophelia pertusa and Madrepora oculata. Although the sponge lives in nutrient-rich areas, we document its carnivorous feeding behavior. The identity of the new species was verified using molecular markers: the species is very closely related to the North-Atlantic Cladorhiza abyssicola, but it differs distinctly, and forms a monophyletic clade. The two species might be considered very close relatives, probably sister species deriving from a common ancestor.

A new species of Abyssocladia (Porifera, Demospongiae, Poecilosclerida, Cladorhizidae) and other carnivorous sponges from the far eastern Solomon Islands.

Two species, one each of Abyssocladia Lévi, 1964, and Asbestopluma Topsent, 1901, are recorded from the far eastern Solomon Islands for the first time. Abyssocladia lakwollii sp. nov. is characterized by the pedunculate disc-shape of the body, the unusually large size of the isochelae I microscleres, and by the shape of the cleistochelae with crossed central teeth. Asbestopluma (A.) desmophora Kelly & Vacelet, 2011, first described from a seamount on Macquarie Ridge (Australia EEZ) and eastern waters to the north and south of New Zealand, is also recorded from the far eastern Solomon Islands. The specimens differ only slightly from their southern counterparts in dimensions of some spicules, and in the ornamentation detail of the basal teeth of the large and small anisochelae. 

Enhanced understanding of predator-prey relationships using molecular methods to identify predator species, individual and sex.

Predator species identification is an important step in understanding predator-prey interactions, but predator identifications using kill site observations are often unreliable. We used molecular tools to analyse predator saliva, scat and hair from caribou calf kills in Newfoundland, Canada to identify the predator species, individual and sex. We sampled DNA from 32 carcasses using cotton swabs to collect predator saliva. We used fragment length analysis and sequencing of mitochondrial DNA to distinguish between coyote, black bear, Canada lynx and red fox and used nuclear DNA microsatellite analysis to identify individuals. We compared predator species detected using molecular tools to those assigned via field observations at each kill. We identified a predator species at 94% of carcasses using molecular methods, while observational methods assigned a predator species to 62.5% of kills. Molecular methods attributed 66.7% of kills to coyote and 33.3% to black bear, while observations assigned 40%, 45%, 10% and 5% to coyote, bear, lynx and fox, respectively. Individual identification was successful at 70% of kills where a predator species was identified. Only one individual was identified at each kill, but some individuals were found at multiple kills. Predator sex was predominantly male. We demonstrate the first large-scale evaluation of predator species, individual and sex identification using molecular techniques to extract DNA from swabs of wild prey carcasses. Our results indicate that kill site swabs (i) can be highly successful in identifying the predator species and individual responsible; and (ii) serve to inform and complement traditional methods.