Testing subspecies hypothesis with molecular markers and morphometrics in the Pacific white tern complex

Abstract

To test the validity of subspecies designations of the white tern, genetic and morphological data were used to assess differences among four putative Pacific subspecies Gygis alba candida, Gygis alba rothschildi, Gygis alba pacifica, and Gygis alba microrhyncha. The origin(s) of a recent colonization of Oahu was also examined using molecular data. Samples were collected from 209 birds, representing island groups of the North and South Pacific. Culmen length and depth, longest and shortest rectrix lengths, and wing chord measurements from an earlier dataset were compared. Mitochondrial DNA variation suggests that there are no phylogenetically distinct species within the Pacific Ocean. The genetic and morphological similarity of G. a. candida and G. a. rothschildi warrants merging them into one subspecies (G. a. candida). Gygis alba microrhyncha and G. a. pacifica are distinctly smaller and larger than the other two subspecies, respectively, but are not completely diagnosable across the morphological characters examined. Although the Pacific subspecies do not exhibit reciprocal monophyly, there is significant genetic differentiation among the two South Pacific groups, G. a. microrhyncha, G. a. pacifica, and all other Pacific subspecies. This differentiation warrants treating these two South Pacific groups as separate management units, but not species or subspecies. Finally, the recently established population of white terns on Oahu shared haplotypes with all subspecies, suggesting multiple origins from populations across the Pacific and confirming contemporary gene flow.

Identifying mechanisms of genetic differentiation among populations in vagile species: historical factors dominate genetic differentiation in seabirds

“…(); 57 , Patirana, Hatch & Friesen (); 58 , Yeung et al . (); 59 , Faria et al . (); 60 , Miller, Mullins & Haig (); 61 , Draheim et al .…”

“…However, (Friesen et al ., ) suggested that geographic distance (‘isolation by distance’) provided only a weak explanation of population genetic differentiation in seabirds, and several species show strong genetic differentiation within single islands or archipelagos (Burg & Croxall, ; Smith & Friesen, ; Wiley et al ., ). However, genetic structure can also exist in the apparent absence of physical barriers to gene flow, suggesting that biotic factors are also important (Burg & Croxall, ; Friesen et al ., ; Yeung, Carlon & Conant, ; Friesen, ).…”

Differentiation of subspecies and sexes of Beringian Dunlins using morphometric measures

“…We used morphological characters that exhibit little variation throughout the annual cycle and that can be quickly measured to determine subspecies and sex in the field. Similar techniques have been used to identify subspecies (Merendino et al 1994, Saitoh et al 2008, Yeung et al 2009) and Fig. 1.…”

“…, Yeung et al. ) and sexes (Shealer and Cleary , Meissner and Pilacka , Dechaume‐Moncharmont et al. ) in a variety of avian taxa.…”

A review of subspecies recognition in polydesmidan millipedes (Diplopoda) with a revision of the subspecies of Euryuridae (Xystodesmoidea)

“…Phylogenetic species concepts vary in operational criteria but rely heavily on genetic information and typically view species as the smallest, indivisible natural unit. Indeed, genetic data are often utilized to test species and subspecies boundaries, sometimes resulting in the dismissal of subspecific taxa by synonymization with the nominate subspecies or elevation to full species (Manier 2004; Mulcahy 2008; Yeung et al. 2009).…”