Cryptic diversity and colonization processes in Ophryotrocha inhabiting mammal bones in the shallow-water Mediterranean Sea

SERGI TABOADA; NANCY SCHULT; MARIA BAS; CARLOS LEIVA; DAMHNAIT MCHUGH

Conferencia; 12th International Polychaete Conference; 2016

Mammal carcasses represent extraordinary marine benthic habitats that harbor diverse polychaete communities, including several members of the dorvilleid genus Ophryotrocha. We studied the colonization patterns of two species of Ophryotrocha (O. puerilis and O. alborana) on mammal bones deployed in the NW Mediterranean: (i) experimental bones deployed at ~20 m for a year near Blanes, with samples collected at 3-month intervals; and ?control? bones deployed (ii) at Blanes harbor (10 m) and (iii) at the head of a nearby submarine canyon (53 m). Molecular analyses for organisms identified as O. puerilis indicate the occurrence of two cryptic species (based on COI divergences and on phylogenetic and species delimitation analyses of COI, 16S rRNA, and Histone 3), one on the experimental bones and another appearing at the head of the submarine canyon. This is the second time that cryptic diversity of Ophryotrocha has been observed on mammal bones and, most importantly, it is found in one of the most widespread groups in the genus across the Mediterranean, which challenges the validity of previous morphologically based identifications of O. puerilis. COI sequences for the most common cryptic species in the survey (experimental bones) revealed shared haplotypes among the different bones and trimesters suggesting continuous recruitment across time, whereas COI sequences for O. alborana revealed unique haplotypes for worms from different bones and trimester samples, indicating three separate recruitment events. Our study suggests that different species of Ophryotrocha have different patterns of bone colonization despite sharing similar life histories.