Douglas Siegel-Causey

CHAPTER 6 – Phylogeny of the Pelecaniformes: Molecular Systematics of a Privative Group

Phylogenetic hypotheses are the critical framework for understanding macroevolutionary patterns and interpreting comparative evolutionary data. Quantitative comparative analysis of the patterns in molecular, behavioral, and morphological evolution requires detailed phylogenies, particularly when character states and transformation series are incompletely known. For these reasons, a better understanding of higher order phylogenies is crucial when group monophyly is problematic and a major evolutionary change has occurred. Understanding the phylogenetic relationships of the pelecaniform birds, therefore, is central to the larger question of understanding the higher level relationships among nonpasserine birds. Critical assessment of the higher order relationships among nonpasserines is one of the most critical issues in avian systematics, and a crucial problem at present is whether the Pelecaniformes is monophyletic. Molecular studies suggest that Pelecaniformes is not monophyletic and the former members are instead grouped with other early branching groups. If these molecular-based studies are validated and Pelecaniformes is dismantled, then the traditional morphological framework that forms the basis for most phylogenetic assumptions in avian systematics is clearly in need of re-examination, as it pertains to modern systematics research.

Historical diversity of cormorants and shags from amchitka island, Alaska

We studied the historical biodiversity of cormorants and shags in the central Aleutians by examining the presence and abundance of bones deposited in two large Aleut middens located on Amchitka Island, Alaska. The temporal range of discrete strata in these deposits was from Russian-era contact to about 2,650 years before present. We found six species in these middens: Pelagic, Red-faced, and Kenyons Shags (Stictocarbo [Phalacrocorax] pelagicus, S. urile, S. kenyoni), Double-crested (Hypoleucus [Phalacrocorax] auritus), Japanese (Phalacrocorax capillatus) and Pallass Cormorants (Compsohalieus [Phalacrocorax] perspicillatus), ranked in order of abundance. Historical patterns of abundance differed among species. Japanese and Pallass Cormorants were most likely chance arrivals to the island; Double-crested Cormorants were not found post-contact and we hypothesize that Arctic Foxes may have extirpated them here; Pelagic and Red-faced Shags have remained in constant proportion over the years and abundances may relate to environmental or climatic change. Little is known about S. kenyoni. These results suggest that the diversity of the marine coastal avifauna has experienced dynamic change during the late Holocene and that the distributions of shags and cormorants in particular were different than now known.

The western Aleutians : Cultural isolation and environmental change

Recent research in the western Aleutians addresses two primary issues: the nature and extent of cultural exchange along the Aleutian chain, and Holocene environmental change and its effects on the development of Aleut culture. Cultural isolation is a major paradigm of researchers working in the Aleutians. Review of the distribution of several cultural traits suggests the Aleuts adopted many cultural elements originating outside the chain, but the distribution of these to the western islands was uneven.

Molecular variation and biogeography of Rock Shags

Molecular analysis of the present genetic structure of Rock Shags indicates significant population subdivision probably caused by vicariant disjunction associated with the Llanquihue Glaciation (35,000-15,000 ybp). The formerly continuous population was forced into refugia on the Pacific and Atlantic coasts, where they remained without contact for approximately 20,000 years. With amelioration of the climate and consequent glacial retreat, populations recolonized rocky shorelines in the central portion of the present day range and introgressed considerably. The Chubut and Falkland populations serve as genetic sources for the others, whereas the Fuegian population acts as a genetic sink. The population that is resident on Isla Chiloe is enigmatic and in nonequilibrium, possibly the result of indirect effects by a yet unsampled population.

Holocene Records of the Antarctic Shag (Phalacrocorax [Notocarbo] bransfieldensis) in Fuegian Waters

The Antarctic Shag can be discriminated from its congeners by five osteological characters. Using these characters, we were able to identify bones of this species in five shell middens located in southern Fuego-Patagonia. The temporal distribution of these elements extends from historical times (280 YBP) to the middle Holocene (6,100 YBP). These extralimital birds may have reached Fuegian waters through chance events, by postbreeding dispersal, or as vagrants from a yet undiscovered Fuegian colony. We discuss the implication of these and other findings on the specific status of the Antarctic Shag and its sympatry with the Imperial Shag. The current designation of the Antarctic Shag is proposed as Notocarbo bransfieldensis (Friedmann 1945).