Abstract:
New Zealand sea anemones have received very little taxonomic investigation. Their species diversity
has not been well characterised, the phylogenetic relationships among clades have not been examined,
and the biogeographic origins of our endemic species are largely unknown. Sea anemones do not leave
behind fossils of their structures, which have so often been used as the baselines for the relationships
between extinct taxa of other groups. Historically, the phylogenetic understanding of sea anemones was
based on morphological classification. In many other groups, morphological classifications have been
substantially revised by molecular phylogenetic studies, and many taxa erected on the basis of
morphology have been discovered to be non-monophyletic.
Gene sequences taken, from nine species sampled across 4 regions, targeted several mitochondrial and
nuclear genes which were amplified and sequenced. A concatenated alignment of each sequenced gene
was constructed using BEAST. Geographic distributions were researched and unified with each
species. BioGeoBEARS was used to estimate the biogeographic history on the dated molecular
phylogeny. No morphologically cryptic species were identified, though the most promising grouping
for morphologically cryptic species was the Oulactis muscosa, Aulactinia veratra, and Isactinia
olivacea clade, which remains consistent with other phylogenetic studies. The only evidence for a
distinctly New Zealand clade and species radiation came from Anthopleura rosea, Aulactinia veratra,
and Isactinia olivacea, as the entire clade is endemic to New Zealand and is reciprocally monophyletic.
Biogeographic analysis shows that the origins of New Zealand sea anemone has been shaped by the
dominance of dispersal from the Pacific rather than by Gondwanan vicariant connections.
New genetic sequences for endemic sea anemones were created, along with the first ever sequences for
Anthothoe vagrans and Isoparactis ferax. These sequences produced the first phylogenetic analysis of
endemic New Zealand sea anemones, showing that sea anemones colonised New Zealand multiple
times in many unique events. Final analysis indicates that the driving factor of sea anemone
biogeographic distributions may be extinction. Extant sea anemones show a far more restricted and
regional distribution than the predicted distributions of ancestral species. Therefore, the current
observed distributions are a result of localised extinction events. These localised extinction events
cause reproductive isolation, which leads to speciation. The asexual reproduction and colonisation
abilities of sea anemone may be a result of sea anemones being quite vulnerable to small scale
extinction events and genetic isolation.