Hydra of Hawaii: phylogenetic relationships with continental species

Revisiting the age, evolutionary history and species level diversity of the genus Hydra (Cnidaria: Hydrozoa)

“…With 28 delimited main lineages we uncovered a much greater diversity of genetic lineages, which may correspond to species, than suggested by previous studies that were based on subsets of the present dataset (Campbell et al, 2013;Hemmrich et al, 2007;Kawaida et al, 2010;Martínez et al, 2010;Reddy et al, 2011;Wang et al, 2012). This underlines the importance of (1) taking into account all available data and (2) to employ specific and objective criteria for delimiting lineages which may subsequently be translated into species.…”

“…The results of this and previous molecular phylogenetic studies (e.g. Campbell et al, 2013;Hemmrich et al, 2007;Kawaida et al, 2010;Martínez et al, 2010;Wang et al, 2012) are an ideal starting point for future analyses combining morphological and molecular phylogenetic analyses to revise the taxonomy and species descriptions of Hydra. Given the restricted geographic distribution of several main lineages delimited herein, it appears plausible that only a subset of Hydra's total diversity has been included in molecular analyses so far.…”

“…This may explain why genetically identical individuals (or strains) were recovered from different continents (Campbell et al, 2013;Martínez et al, 2010), for example identical genotypes of H. vulgaris 4 in America and New Zealand, of H. viridissima 3 in Australia and Germany and of H. viridissima 5 in Europe, North America and Africa (a potential source of error could be the long-term maintenance of some strains in different laboratories). However, for several species with wide geographic distributions -like H. vulgaris 7 across Eurasia and South Africa or H. oligactis and H. circumcincta 1 & 2 across northern Europe and North America -the recovered genotypes were closely related but not identical as would be expected for recent human-mediated dispersal.…”

“…In the last years several molecular phylogenetic studies shed light on the diversity within Hydra (Campbell et al, 2013;Hemmrich et al, 2007;Kawaida et al, 2010;Martínez et al, 2010;Reddy et al, 2011;Wang et al, 2012). The most detailed studies regarding the number of studied individuals (=strains) were those by Kawaida et al (2010) and Martínez et al (2010).…”

“…those published by Campbell et al, 2013;Hemmrich et al, 2007;Kawaida et al, 2010;Martínez et al, 2010;Reddy et al, 2011 andWang et al, 2012). This extensive dataset was complemented with some newly sequenced strains (mainly of the viridissima group).…”