Sunday, April 21, 2013

[Ornithology • 2008] Convergent Evolution of Hawaiian and Australo-Pacific Honeyeaters from Distant Songbird Ancestors


Until the 1980s, when the last one went extinct, five species of Hawaiian honeyeaters sipped nectar from Hawaii's flowers. These songbirds, illustrated at lower left (Hawaii ‘o’o) and upper center (kioea), have always been considered Australasian honeyeaters (family Meliphagidae; two on right branch) and share many similarities in form, behavior, and ecology. However, DNA sequence analysis of museum specimens by Fleischer, James, and Olson reveal that the Hawaiian species are distantly related to meliphagids and instead form a new songbird family, the Mohoidae, related to Holarctic waxwings (shown at upper left), neotropical silky flycatchers, and related families. The mohoids and meliphagids are a remarkable example of convergent evolution and are the only bird family known to go extinct over the past few centuries.

Summary
The Hawaiian “honeyeaters,” five endemic species of recently extinct, nectar-feeding songbirds in the genera Moho and Chaetoptila, looked and acted like Australasian honeyeaters (Meliphagidae), and no taxonomist since their discovery on James Cook's third voyage has classified them as anything else. We obtained DNA sequences from museum specimens of Moho and Chaetoptila collected in Hawaii 115–158 years ago. Phylogenetic analysis of these sequences supports monophyly of the two Hawaiian genera but, surprisingly, reveals that neither taxon is a meliphagid honeyeater, nor even in the same part of the songbird radiation as meliphagids. Instead, the Hawaiian species are divergent members of a passeridan group that includes deceptively dissimilar families of songbirds (Holarctic waxwings, neotropical silky flycatchers, and palm chats). Here we designate them as a new family, the Mohoidae. A nuclear-DNA rate calibration suggests that mohoids diverged from their closest living ancestor 14–17 mya, coincident with the estimated earliest arrival in Hawaii of a bird-pollinated plant lineage. Convergent evolution, the evolution of similar traits in distantly related taxa because of common selective pressures, is illustrated well by nectar-feeding birds, but the morphological, behavioral, and ecological similarity of the mohoids to the Australasian honeyeaters makes them a particularly striking example of the phenomenon.


On the cover: Until the 1980s, when the last one went extinct, five species of Hawaiian honeyeaters sipped nectar from Hawaii's flowers. These songbirds, illustrated at lower left (Hawaii ‘o’o) and upper center (kioea), have always been considered Australasian honeyeaters (family Meliphagidae; two on right branch) and share many similarities in form, behavior, and ecology. However, DNA sequence analysis of museum specimens by Fleischer, James, and Olson reveal that the Hawaiian species are distantly related to meliphagids and instead form a new songbird family, the Mohoidae, related to Holarctic waxwings (shown at upper left), neotropical silky flycatchers, and related families. The mohoids and meliphagids are a remarkable example of convergent evolution and are the only bird family known to go extinct over the past few centuries.
Illustration by John Anderton.

Figure 2. Illustrations of Three of the Five Species of Hawaiian “Honeyeaters” and Three Representative Meliphagid Honeyeaters 
The three Hawaiian taxa represent the three primary morphological types found in Hawaiian “honeyeaters” (Mohoidae: [A], Moho nobilis; [C], Chaetoptila angustipluma; and [E], Moho braccatus). The three meliphagids include one from New Zealand ([B], Prosthemadera novaeseelandiae), one from Australia ([D], Anthochaera carunculata), and one from Samoa ([F], Gymnomyza samoensis).

Paintings by John Anderton 

R Fleischer, H James, S Olson. 2008. Convergent Evolution of Hawaiian and Australo-Pacific Honeyeaters from Distant Songbird Ancestors. Current Biology. DOI: http://dx.doi.org/10.1016/j.cub.2008.10.051

When is a Honeyeater not a Honeyeater& The Tricks of Convergent Evolution http://on.natgeo.com/11bsyFs   
Picture of the Week — Hawaiian Honeyeaters http://blogs.smithsonianmag.com/science/2008/12/picture-of-the-week%e2%80%94hawaiian-honeyeaters via @SmithsonianMag

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