title: Trematodes with a reproductive division of labour: heterophyids also have a soldier caste and early infections reveal how colonies become structured.
abstract: Recent findings have extended the documentation of complex sociality to the Platyhelminthes, describing the existence of a reproductive division of labour involving a soldier caste among the parthenitae of trematode parasites. However, all species examined to date occupy high positions in trematode interspecific dominance hierarchies and belong to two closely related families, the Echinostomatidae and the Philophthalmidae (Superfamily Echinostomatoidea). Further, the two species documented as lacking soldiers also belong to the Echinostomatidae. Here, we examine four species of intermediate dominance, all belonging to the family Heterophyidae (Superfamily Opisthorchioidea): Euhaplorchis californiensis, Phocitremoides ovale, Pygidiopsoides spindalis and Stictodora hancocki, all of which infect the California horn snail, Cerithideopsis californica (=Cerithidea californica). We quantify morphology, distribution and behaviour of rediae from fully developed colonies. We also provide information on colony structure for three developing heterophyid colonies to better understand colony development. We discuss the implications of our findings, particularly with respect to how they suggest alternatives to the conclusions of other researchers concerning the nature of trematode sociality. Our analyses of morphological, distributional and behavioural patterns of developed colonies indicate that these heterophyid trematodes have a non-reproductive caste whose function is defence of the colony from invading trematodes. Hence, a soldier caste occurs for species lower in dominance hierarchies than previously known, and is present in at least two superfamilies of digenean trematodes, suggesting that selection for a soldier caste may be much more common among the Trematoda than previously recognised.
authors.affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA. Electronic address: vedrenne@lifesci.ucsb.edu.
authors.forename: Ana E
authors.initials: AE
authors.lastname: Garcia-Vedrenne
authors.affiliation: College of Creative Studies, University of California, Santa Barbara, CA 93106, USA; Department of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Durham, NC 27708, USA.
authors.forename: Anastasia C E
authors.initials: AC
authors.lastname: Quintana
authors.affiliation: College of Creative Studies, University of California, Santa Barbara, CA 93106, USA; Department of Animal Science, University of California, Davis, CA 95616, USA.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: DeRogatis
authors.affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA; Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA 24061, USA.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Dover
authors.affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Maribel
authors.initials: M
authors.lastname: Lopez
authors.affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA; College of Creative Studies, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Armand M
authors.initials: AM
authors.lastname: Kuris
authors.affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA; Scripps Institution of Oceanography, Marine Biology Research Division, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Ryan F
authors.initials: RF
authors.lastname: Hechinger
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D044822:Biodiversity; D002140:California; D004450:Echinostomatidae / Q000033:anatomy & histology / Q000145:classification / Q000502:physiology; D006578:Heterophyidae / Q000033:anatomy & histology / Q000145:classification / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D012908:Snails / Q000469:parasitology; D012919:Social Behavior; D013045:Species Specificity; D014200:Trematoda / Q000472:pathogenicity / Q000502:physiology*; D014201:Trematode Infections / Q000469:parasitology
keywords: Colony; Defence; Digenea; Rediae; Sociality; Soldier caste; Trematoda