Introduction to Systematics:

• phylogeny: evolutionary relationships among species
• systematics: study of evolutionary relationships (phylogeny) and of species identity
• studied based on characteristics
• homology: characteristics in common because of common ancestry; show relationships
• convergent evolution: characters in common because have independently evolved; do not show relationships (a problem for studies of systematics.)
• rates of evolution: if variable, characters can be misleading, especially if based on a measure of overall how similar species are

Morphological traits such as:

• palate type; skeletal structure; syringeal structure; limb muscles

• vocalizations; courtship displays; nest structure

• DNA-DNA hybridization : used by Sibley & Ahlquist to derive phylogeny of bird orders, families, some species.

• hybridize single DNA strands from two different species
• determine temperature at which 50% of the DNA forms stable hybrids this temperature is proportional to the similarity of the DNA strands
• DNA-DNA hybridization examines overall similarity of DNA between species so it will give an accurate estimate of phylogeny only if evolutionary rates are on average constant
• DNA sequencing
• mitochondrial DNA (non-coding: species, subspecies; protein coding: genera, families
• nuclear DNA (various levels)
• ribosomal DNA/RNA (early divergences among avian groups)

• DNA-DNA hybridization: all of genome used
• other traits (DNA sequence or behavior or morphology): traits reflect only a small part of the genome

• DNA-DNA hybridization: unknown.
• DNA sequence, behavior, morphology: since use discrete characteristics, can calculate statistics to evaluate the level of convergence; have more confidence in tree if convergence is low

• DNA-DNA hybridization: strongest dependence on uniform average rate of DNA evolution

• Different studies where pair-wise comparisons have been done for DNA-DNA hybridization differ in whether condition met:
• Sibley and Ahlquist's ratite data: condition is met
• Houde's results: for two groups (old world warbler species, thrush species) for which data available, condition is NOT met

Some proposed relationships among avian orders:

Relative well-supported relationships (supported by more than one kind of data):

• Paleognathae (ratites and timamous) vs. Neognathae (all other birds):  Supported by palate structure and DNA-DNA hybridization
• Close relationship between Anseriformes and Galliformes: supported by DNA-DNA hybridization and some morphological characters
• Close relationship between Gruiformes and Charadriiformes suggested by DNA-DNA hybridization and hind-limb muscles; both these methods suggest that some groups currently placed in the Gruiformes may belong in the Charadriiformes
• Close relationship between Apodiformes and Passeriformes supported by DNA-DNA hybridization and hind-limb muscles. The Apodiformes (swifts and hummingbirds) may belong together as suggested by the classification, or one or the other might be more closely related to the Passeriformes

• Strigiformes.  DNA-DNA hybridization places them with Caprimulgiformes; hind-limb muscles and some other morphological traits place them with Falconiformes.
• Phoenicopteriformes.  DNA-DNA hybridization and some leg muscle data place them with Ciconiiformes; other leg muscle data and skeletal characters place them with Charadriiformes
• Some other orders (ex: Columbiformes, Psittaciformes) each have so many of their own unique characteristics that finding traits that link them to other groups has been difficult; their relationships to other groups are thus not known

Suboscines: worldwide group; New World Flycatchers, manakins, cotingas, woodcreepers, antbirds, pittas, ovenbirds, and allie.  Share characteristics of syrinx; simpler song than oscines

Oscines: worldwide group; unique complex syrinx; often have complex, learned song.  Main oscine groups (based on DNA-DNA hybridization; some also confirmed by hind-limb muscles and some other morphological characters):

• crow relatives: crows, jays, Old World orioles, drongos, shrikes, vireos, numerous Australasian groups.  Crows & jays worldwide; others primarily old world.
• thrush relatives: thrushes, waxwings, dippers, starlings, mockingbirds, old world warblers, old world flycatchers.  Worldwide group.
• Old World insecteaters: worldwide group (probably originated in the Old World then spread); nuthatches, creepers, wrens, babblers, chickadees, swallows, etc.
• Weaver relatives: worldwide with most diversity in old world. Larks, old world sparrows, accentors, weavers, sunbirds, etc.
• Nine-primaried oscines: primarily new world group, some members in old world, none in Australasia.  New world warblers,  new world sparrows, buntings, cardinals, finches, blackbirds & allies.