Its Old World members, the Water, African and Madagascan rails, form a superspecies, and are thought to have evolved from a single invasion from across the Atlantic.
Differences in songs, genetics and morphology suggests that the Azores were colonised in a single invasion in the late Pleistocene, about 100,000 years ago.
Based on evidence of significant genetic variation at the regional level, no differences between habitats, and overlapping haplotypes (Figs. 2 & 3, Table 1), we reject our initial hypothesis that urban populations have become established following a single invasion event with subsequent human-mediated dispersal responsible for a continent-wide distribution.
Relationships among these genera suggest a single invasion from Old World to New World, followed by development of the full adult hindwing eyespot in the Nearctic Paonias and Smerinthus, a shift from monophagy to polyphagy in the former genus and reinvasion of the Palearctic by one or more lineages of the latter.
This phylogeny was consistent with a single invasion of deep-water environments followed by a holarctic expansion by Strongylocentrotus.
To this point we have focused solely on a single invasion event into a resident population consisting entirely of susceptibles.
In experiments over a single invasion cycle the invasion rate for each parasite line cultured in triplicate was determined by dividing the final by the starting parasitaemia.
Although these rather restrictive conditions might lead one to conclude that a single invasion of wSinvictaA into S. invicta seems unlikely, this is not necessarily the case.
Following origination ˜62 Ma (Bernecker & Weidlich, 1990), molecular phylogeny indicates stylasterid corals diversified extensively in the deep sea before making three distinct invasions of the shallow-water tropics and a single invasion of temperate shallow water (Lindner, Cairns & Cunningham, 2008).
It is difficult to draw specific conclusions based on the limited taxon sampling presented herein, but the Ves insertion phylogeny recovers monophyletic clades of Neotropic and Nearctic species, indicating a single invasion into each of these regions.
In other island mice colonization studies, it was found that although mitochondrial patterns similarly suggest only a single invasion, there could still be continued male mediated gene flow [ 15, 18].
