Date of Award
Master of Science
Dr. Alec Lindsay
Avian phylogenetic analysis based on DNA sequences, rather than morphological characters, has been used in recent decades to resolve systematic relationships. Advancements in molecular techniques have improved avian phylogenetics and have led to new insights on the relationships between and within taxa. Loons (Aves: Gaviiformes) are one of the oldest living lineages of birds, and the order includes five extant species. The morphological cladogram of Gavia placed G. arctica as a sister species to G. pacifica. However, a more recent study based on mtDNA resulted in a discordant tree splitting the G. arctica/G. pacifica clade, and placed G. pacifica as sister to the (G. immer, G. adamsii) clade. These hypotheses were tested using next-generation sequencing (NGS) data in the form of a RAD-tag dataset comprising 232,094 bps from 2502 variable loci. Bayesian inference, Maximum Likelihood, and Maximum Parsimony phylogenetic analyses of a concatenated dataset strongly supported the traditional phylogeny (G. stellata, ((G. arctica, G. pacifica), (G. adamsii, G. immer))), and differed from the largely mitochondrially-based hypothesis that placed G. pacifica sister to the (G. immer, G. adamsii) clade. Both internally- and externally-calibrated molecular clock based estimates of divergence dates placed the most recent common ancestor of modern loons in the early Miocene, which is earlier than previously thought, ~21.4 mya (20-22.8 mya) provides a more parsimonious explanation for body size evolution in loons.
Sprengelmeyer, Quentin D., "A PHYLOGENETIC REEVALUATION OF THE GENUS GAVIA (AVES: GAVIIFORMES) USING NEXT-GENERATION SEQUENCING" (2014). All NMU Master's Theses. 1.