Hierarchical biogeographical processes largely explain the genomic divergence pattern in a species complex of sea anemones (Metridioidea: Sagartiidae: Anthothoe )

GOMEZ-UCHIDA, DANIEL; ACUÑA, FABIÁN H.; SEEB, LISA W.; HÄUSSERMANN, VRENI; GRIFFITHS, CHARLES; SPANO, CARLOS A.

MOLECULAR PHYLOGENETICS AND EVOLUTION

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2018 vol. 127 p. 217 - 228

1055-7903

The phylogeneticresolution provided by genome-wide data has demonstrated the usefulness of RAD-tagsequencing to tackle long-standing taxonomic questions. Cnidarians have recently become a model group in thisregard, yet species delimitation analyses have been mostly performed inoctocorals. In this study,we use RAD tags to test the species hypotheses in a wide-spread complex of seaanemones (genus Anthothoe),contrasting this new line of evidence with their current classification. Thealternative hypotheses were tested using a Bayes Factors delimitation methodand the most probable species tree was then evaluated under differentbiogeographic scenarios. Our results decisively reject the currentmorphology-informed delimitation models and infer the presence of severalcryptic species associated with distinct marine ecoregions. This spatial patternwas remarkably consistent throughout the study, highlighting the role ofgeographic distribution as a powerful explanatory variable of lineages diversification.The southern Gondwana pattern with episodic, jump dispersal events is thebiogeographic historical representation that best fits the Anthothoe species tree. The high population differentiationpossibly amplified by the occurrence of asexual reproduction makes it difficultto identify genes responsible for local adaptation, however, these seem to bemainly associated with cellular and metabolic processes. We propose a new setof species hypotheses for the Southern Hemispheric Anthothoe clade, based on the pronounced genomic divergenceobserved among lineages. Although the link between the genetic and phenotypicdifferentiation remains elusive, newer sequencing technologies are bringing uscloser to understanding the evolution of sea anemone diversity and, therefore,how to appropriately classify them.