Even with a diversity of primary research projects,
there are still many research interests which don't fit into
any of the other categories. So, here are some brief descriptions
of additional efforts.
Novel Origin of Song Learning in Suboscine Passerine Birds
Song learning was previously known from three clades of birds– oscine passerines (song birds), parrots and hummingbirds. In collaboration with Don Kroodsma, Deb Hamilton, and George Powell, we have applied population genetic methods to test the hypothesis that one species of suboscine passerine– the Three-watttled Bellbird Procnias tricarunculata– has independently evolved social song learning. The results show that breeding population of P. tricarunculata that have very diverse songs are not genetically distinct, strongly supporting the conclusion that song variation is socially determined. This constitutes the fourth origin of song learning in birds, and only the seventh amongst all animals.
Saranathan, V., Hamilton, D., Powell, G., Kroodsma, D., and Prum, R. O. 2007. Genetic evidence supports song learning in the Three-wattled Bellbird Procnias tricarunculata (Cotingidae). Molecular Ecology 16: 3689-3702.
Suboscine Syringeal Morphology
The syrinx, or vocal organ, of suboscine passerines
is extremely diverse in morphology. Having described the syringeal
morphology of manakins (Pipridae) and broadbills (Eurylaimidae),
and having nearly completed description of the syringes of
Cotingas (Cotingidae), I am interested in a monograph on the
syringeal morphology of the entire suboscine bird clade.
Syringeal Complexity and Vocal Complexity
The suboscine birds are distinct from the oscine
passerines (or songbirds) in lacking extensive song learning
capability. Consequently, their syringeal diversity provides
a great opportunity to investigate the relationship between
syringeal structure and vocal complexity. Within the suboscines,
there are multiple independent origins of intrinsic syringeal
musculature, fused tracheal drums, and many other morphologies.
Comparative analyses of structural diversity and vocal complexity
(e.g. rapidity of vocal modulations) could document for the
first time how selection on vocal features contributes to
morphological diversification in birds.
Syringeal Complexity and Neural Complexity
The syringes of suboscine birds vary tremendously
in the complexity of musculature, but almost nothing is known
about the complexity of the neural system that is required
to drive that diversity of muscles. Do more complex syringes
with 1-3 pairs of intrinsic muscles also require derived neural
circuits to drive them? I am interested in exploring the diversity
of suboscine syringeal muscles, vocalizations, and brain organization
to test these hypotheses.
Clique or Compatibility Analysis in Historical
Component analysis, Brooks Parsimony analysis,
and other methods provide different options in reconstruction
of vicariance. But these methods can lead to errors when data
reflecting alternative biotic histories are combined. Because
biota do not have singular histories as organismal phylogenies
do, phylogenetic techniques are not appropriate for historical
biogeographic reconstruction of areas with complex histories.
An alternative method is clique or compatibility analysis.
We are a compatibility analysis based on the ranges of Neotropical
lowland forest birds to test the efficacy of these methods.