Last week was the joint conference of the American Ornithologist's Union, the Cooper Ornithological Society and the Society of Canadian Ornithologists in Portland, Oregon. There were many excellent presentations on a variety of topics in ornithology. Below are, in my opinion, some of the highlights from the conference representing the cutting edge of avian research in North America.
- Rosemary Grant of Princeton University presented a plenary lecture summarizing her collaborative work with her husband, Peter Grant, and numerous students and post-docs on the evolutionary biology and ecology of Darwin's Finches in the Galapagos Islands. The Grants' work on selection on bill size in Darwin's Finches is a classic work, arguably the most famous and well supported examples of Darwinian natural selection in the wild. Now the Grants are tackling speciation and presenting their ideas on how Darwin's Finch species arise over time. Whether or not many currently recognized species of Darwin's Finch are indeed true evolutionary species or complex, polymorphic populations was a hot topic of debate behind the scenes in the lobbies of the Hilton and the bars and restaurants on the streets of Portland. It remains to be seen how the Grants' ideas on speciation will stand up to the scrutiny of their ornithological peers.
- Terry Chesser of the National Museum of Natural History along with co-authors from museums around the country such as the University of Kansas and Louisiana State University presented new data on the relationships of one of the largest and most problematic groups of passerine birds, the Neotropical ovenbirds of the family Furnariidae. The woodcreepers were found to be monophyletic (meaning all the birds currently assigned to the woodcreeper group were found to share a single common ancestor). Two main groups were distinguished within the Furnariidae the woodcreepers and the "true" furnariids, or simply the rest of the furnariids.
- Townsend Peterson of the University of Kansas discussed the power of museums in understanding the spread of animal-borne diseases (aka zoonotic diseases). The "bird-flu" or H5N1 virus has the potential for a global pandemic and since 2003 has persisted as a lingering threat to human health, especially in south and south-east Asia. Peterson's group found in surveys of birds collected from south China that H5N1 is not exclusively a disease found in galliform birds (chickens, etc.) and waterfowl but is also found among passerines (i.e. songbirds) and other wild landbirds. Peterson also used bird banding databases to model the potential outbreak of zoonotic, bird-borne diseases, like H5N1, in North America and found that where the outbreak starts can have dramatics effects on the spread and geography of the subsequent spread. All of these findings can only be possible with large museum-led databases of both specimens and large scale sighting and banding records.
- John Wieczorek of the University of California at Berkeley presented an update on the ORNIS database. ORNIS is a distributed database that links together avian data from dozens of museum collections. Today the ORNIS database allows one not only to access holdings on avian specimens but also millions of sighting and banding records, digital photos and sound recordings. Wieczorek also discussed a new online tool, BioGeomancer, to add georeferencing data to existing specimen, photo, recording and sighting records. The power of these online, distributed databases and the georeferencing tools that accompany them was seen in numerous talks during this meeting. With adoption of it's new KE EMu database Cincinnati Museum Center is poised to join these other institutions in making it's collection more accessible and usable by researchers in novel and powerful ways.
- An entire session was devoted to the hot topic of subspecies in ornithology. The traditional way in which scientists name species is the binomial, the familiar genus and species names given to every organism. However, there is variation within species and to incorporate this variation into taxonomy many have adopted a trinomial system of nomenclature consisting of three names for each species, genus, species and subspecies. Kevin Winker of the University of Alaska at Fairbanks gave a good history of the use of trinomial nomclature in ornithology and discussed why divergence in phenotpyes (those characteristics of an organisms most often accessible to direct observation such as size, color, etc.) is not also equal to genetic divergence. This means that often the readily observable, physical traits used to distinguish between different subspecies of birds may not correspond to much genetic variation and thus may be of little evolutionary significance when it comes to distinguishing independent genetic lineages. Susan Haig of the USGS Forest and Rangeland Ecosystem Science Center discussed the problems that differing species concepts and subspecies designations pose for conservation efforts. Haig believes that subspecies designations are critical for conservation and law enforcement purposes even if their biological footing is less than solid. These points were hotly debated in the session and in discussions outside the talks.
- Perhaps my favorite talk of the entire conference was by Matt Carling and Rob Brumfield of the Louisiana State University Museum of Natural History. An idea in evolutionary biology known as Haldane's Rule says that in hybrids the sex that contains two different sex chromosomes (the heterogametic sex) should be less fit than the sex that contains two of the same sex chromosomes (the homogametic sex). A bad version of a gene can be overruled by the action of a good version of the same gene on another chromosome. Therefore heterogametic hybrids will be affected by all deleterious alleles on a sex chromosome. Haldane's Rule has been shown to predict the weaker sex in hybrids in everything from insects to mammals. In humans, and most other mammals, males are the heterogametic sex by virtue of having X and Y sex chromosomes while females are the homogametic sex having two X chromosomes. However, in birds females are the heterogametic sex with W and Z chromosomes and males with two Z chromosomes. Lazuli and Indigo Buntings hybridize in the central US. Carling and Brumfield measured the change in gene frequency across a hybrid zone between Lazuli and Indigo Buntings for both nuclear genes and genes linked to the sex chromosomes. They found much smaller genetic clines for sex-linked loci than for autosomal loci (those loci on chromosomes other than sex chromosomes). This is consistent with sex linked genetic incompatibilities in the hybrids. They also identified one locus in particular that contributed very heavily to this narrow genetic cline in Lazuli and Indigo Buntings. This loci was matched to a similar sequence in the chicken genome which, in chickens, contributes to the failure to lay eggs. Essentially Carling and Brumfield have identified an important gene which contributes to the maintenance of Lazuli and Indigo Buntings as discrete species. An amazing study which I hope to hear more about in the future.
- A fantastic symposium was presented on the last day of the conference in which some of the top curators and collections managers in ornithology presented techniques on preparing and managing material in avian collections. University of Kansas curator Mark Robbins and University of Washington Professor Emeritus Sievert Rohwer presented a live demonstration of their study skin preparation techniques. With some relatively minor differences our volunteers in the ornithology collection at Cincinnati Museum Center are preparing specimens like the pros do it, however, I did pick up some useful tips that will improve our specimens. Kimberly Bostwick of the Cornell University Museum of Vertebrates demonstrated her techniques for preparing skeletal material from bird specimens, again as a live demonstration. This was also very useful as here at Cincinnati Museum Center we plan on a major push towards increasing the collection's avian skeletal holdings. Also, Kevin Winker of the University of Alaska at Fairbanks presented a general overview of the tools of the trade for avian collecting from the intricacies of the permitting process to auxillary barrels for a shotgun! All of the talks in this session provided useful tips for the growing bird collection at Cincinnati Museum Center but they also reaffirmed that the changes implemented in our protocols have put us on the right track towards having a world class ornithology collection.
-Finally Irby Lovette of Cornell University presented some interesting, if not troubling, results on measuring genetic diversity using molecular genetic markers. Researchers for various reasons often want to know the genetic diversity of an individual organism. Genetic diversity in an individual is typically measured in terms of heterozygosity. At any particular location in an individual's genome (at least for sexually reproducing organisms) there will be two copies of a particular gene. If those two copies are the same the individual is homozygous at that locus if they differ then the individual is heterozygous a that locus. Researchers use different types of genetic markers to determine the degree to which an individual is heterozygous across it's entire genome. However, Lovette demonstrated that different markers do not agree with one another on genome-wide heterozygosity. A level of heterozygosity determined using one type of marker may not correspond to the same level determined by another marker. Even multiple loci of the same types of markers often do not agree. This work is consistent with previous findings showing that levels of relatedness and inbreeding were only evident using very large numbers of genetic loci and that molecular genetic markers were inferior to good pedigree data in determining genetic diversity. However, there are many correlations in birds between molecular genetic based genetic diversity and various fitness measures, such as hatching success or growth or behavioral measures. The question then is what do these correlations mean? This will be a fertile field for future research for sure!