Proposal (#183) to South American Classification Committee

Change linear sequence of the penguins (Spheniscidae)

Effect on South American CL: This would make changes linear sequence of the penguins to reflect recent genetic data.

Background: Our current sequence of the penguins is a conventional one, based on Falla and Mougin (1979) sequence in Peters Checklist. There is no controversy in the monophyly of this group, or even that of genera.

Our linear sequence is thus:

SPHENISCIDAE (PENGUINS)
Aptenodytes patagonicus King Penguin
Aptenodytes forsteri Emperor Penguin (V) 2
Pygoscelis papua Gentoo Penguin 3
Pygoscelis adeliae Adelie Penguin (V) 4
Pygoscelis antarcticus Chinstrap Penguin (NB) 3
Eudyptes robustus Snares Penguin (V) 5
Eudyptes sclateri Big-crested Penguin (V) 6, 7
Eudyptes chrysocome Rockhopper Penguin 8, 9
Eudyptes chrysolophus Macaroni Penguin 10
Eudyptula minor Little Penguin (V) 11
Spheniscus humboldti Humboldt Penguin 12
Spheniscus magellanicus Magellanic Penguin 12
Spheniscus mendiculus Galapagos Penguin

New information: Baker et al (2005) have constructed a strongly supported phylogeny of this group based on 5851bp of mtDNA and nuclear DNA. They sampled members of all 18 species of penguins, plus two outgroups in their study. Overall branches of the phylogeny are strongly supported (Bayesian posterior probabilities, bootstraps), particularly the basal nodes. They continue by estimating times of divergence and fitting this to a model of climatic cooling as a driving force behind the expansion of the group outside of Antarctica and radiation of more derived genera.

The Antarctic genera, Aptenodytes and Pygoscelis were basal in all trees. Of the remaining penguins, the crested penguins form one clade, while the banded penguins and little penguins form a second clade. The Little Penguins (they consider Eudyptula albosignata the White-flippered Penguin as separate from the Little Penguin E. minor). Within Spheniscus the Pacific species (S. humboldti and mendiculus are sisters) while S. magellanicus is sister to the African demersus. Within the crested penguins, they find that the Erect-crested, Big-crested in our list, Eudyptes sclateri is the basal Eudyptes (Megadyptes is basal to Eudyptes). The Rockhopper (Eudyptes chrysocome) is more closely related to Fiordland (E. pachyrhynchus) and Snares (E. robustus), forming a clade separate from that of the Macaroni (E. chrysolophus) and Royal (E. schlegeli). Nothing here is all that surprising, in fact it is quite well in line with traditional taxonomy with just a few changes here and there. The taxonomic status of species which have been controversial in terms of their status such as Eudyptes schlegeli and Eudyptula albosignata are not tackled in this study.

The suggested sequence is as follows:

SPHENISCIDAE (PENGUINS)
Aptenodytes patagonicus King Penguin
Aptenodytes forsteri Emperor Penguin
Pygoscelis adeliae Adelie Penguin
Pygoscelis papua Gentoo Penguin
Pygoscelis antarcticus Chinstrap Penguin
Eudyptula minor Little Penguin
Spheniscus humboldti Humboldt Penguin
Spheniscus mendiculus Galapagos Penguin
Spheniscus magellanicus Magellanic Penguin
Eudyptes sclateri Big-crested Penguin
Eudyptes chrysolophus Macaroni Penguin
Eudyptes chrysocome Rockhopper Penguin
Eudyptes robustus Snares Penguin

Analysis and Proposal: This phylogeny appears to be solid, and for the most part it matches quite well with published taxonomies of this group. There is nothing revolutionary in the phylogeny itself, the paper's interest is largely the model suggested for expansion of the group out of Antarctica and speciation thereafter. I will note that it is great to have a molecular phylogeny that actually includes all living species of a group.

Recommendation: Because our linear sequence and classification should reflect phylogenetic data, and because the data appear solid, I will vote YES on this new re-arrangement of the penguins.

References:

BAKER, A.J., S.L.PEREIRA, O.P. HADDRATH, AND K-A. EDGE. 2005. Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling. Proceedings of the Royal Society B: 1-7.

FALLA, R. A., AND J.-L. MOUGIN. 1979. Order Sphenisciformes. Pp. 121-134 in "Check-list of birds of the World, Vol. 1, Second Edition" (Mayr, E. & G. W. Cottrell, eds.). Museum of Comparative Zoology, Cambridge, Massachusetts.

Alvaro Jaramillo, October 2005

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Comments from Robbins: "YES. Information by Baker et al. (2005) seems solid."

Comments from Remsen: "YES. Of interest in looking at Baker et al. (2005) is that the previous analyses based on phenotypic characters, from myology to behavior, all differ from one another and from the solid genetic data of Baker et al.; however, Sibley-Ahlquist DNA-DNA hybridization data entirely consistent with the DNA sequence data."

Comments from Stiles: "YES. No problems here, the genetic data seem solid and the change is not profound in any case."

Comments from Zimmer: "YES. The genetic data are convincing."

Comments from Nores: "YES. La secuencia aparece como coherente y está basada en un buen análisis genético. Además no significan cambios importantes que hagan dudar de la veracidad del análisis, como en el caso de Sternidae."

Comments from Pacheco: "YES. A sequência tradicional pode enfim ser alterada com boas razões!"