Thursday, February 11, 2010

Time to Migrate

Its the final day of the joint conference of the Cooper Ornithological Society, the American Ornithologists' Union, and the Society of Canadian Ornithologists in San Diego. It has been a fantastic week. The morning session began with the young professional presentations. Three new professionals were selected to compete for a winning prize. They were provided an extended presentation slot in morning the plenary session.

The first presenter addressed latitudinal gradients in clutch size variation. There are multiple theories explaining this phenomenon including risk of nest predation and availability of food. This study focused trying to resolve this issue. First learning: there is significant variability between taxa. Second: those species with high adult mortality rates did follow the established predation risk hypothesis, but those with lower risk did not. In a controlled study where brood size was decreased it was shown that species with high annual mortality did not decrease per nestling provisioning rate as they were likely trying to ensure this brood was successful (might not get another). Those with low annual mortality rates, and thus many more future reproduction cycles, did decrease provisioning rate, apparently saving energy for future broods.

Second up was a study on suboptimal reproductive sharing in cooperative crows. Why is inbreeding so rare? There are costs. For example inbreeding depression or decreased fitness as compared to non inbred individuals. The benefits of inbreeding include getting a greater percentage of your genes into the next generation. So why is it so rare? The study focused on 30 families of crows over 6 years using nest monitoring, genetics, etc. Findings: 4% incestuously inbred (parent sibling or sibling-sibling), 16% by second order kin (aunts or uncles). Continued monitoring has shown that inbred birds had a much higher and significant mortality, mostly from disease. The researcher went on to define a fitness equation for this type of relationship using the data from the field. The model did not match when run with the most likely costs or the maximum costs of inbreeding, but it did match strongly for the minimum cost of inbreeding. This implies that the costs of inbreeding could be over estimated. Would expect it to be higher as these urban birds have higher populations and higher stress (bad food), but why lower? More questions than answers. Could it be that while most inbreeding pairs lose fitness, occasionally a winning inbred combination occurs? This was a very impressive talk.

The last of the young professionals studied the genetics of high altitude adaptation in Rufous-collared Sparrows. This South American species is distributed from sea level to over 4500 meters! The focus is on two genes, one for oxygen transport (hemoglobin) and one for oxygen processing (mitochondria processes). The high altitude birds did demonstrate a mutation in their hemoglobin which decreased phosphate affinity and increased oxygen affinity. There are two mutations. The low elevation birds had neither, the mid elevation had one, and the high elevation had both. For oxygen processing, early results do show different haplotypes which are related to elevation. The next step looks into gene expression differences as it relates to acclimation. This was performed by transporting birds from native high elevation territory to lower elevations. At there home range these birds had high expression of these critical genes. When moved lower, within a week, the gene expression was drastically altered demonstrating rapid acclimation, much faster than seen in other species. Lots of continued work in this area.

This morning's keynote was much shorter than previous days due to the young professionals presentations. The keynote focused on why species are not more distributed than they are. The focus was on Western Bluebirds which are currently expanding their range. Aggression is functionally correlated with dispersion indicating that more aggressive individuals are more likely to disperse. The researchers have shown that the aggression is higher at the invasion front and lower at more established locations. The Western Bluebird is also very successful at displacing the sister species, the Mountain Bluebird, as a result of its higher aggression. They have also shown that aggression is determined by genetics indicating that the dispersers are truly different than the core of the population. They also demonstrated that aggressive individuals had highest fitness when colonizing and non-aggressive individuals had highest fitness in non-colonizing environments, which is the stabilizing force of this relationship. Bluebirds are dependent upon fire to modify forests for appropriate nest cavities, but this only lasts a few years. As a result, they must have a life history strategy to constantly expand territory to new areas. Bad news for Mountain Bluebird? Not really. Mountain Bluebirds have a higher individual dispersal pattern and higher elevation capabilities. This will be an interesting study to watch going forward.

For the morning sessions I focused on the bio-geography track. There was a study on historical high elevation adaption. This broad study found 4 different strategies based on timing of evolutionary divergence. The most ancient appears consistent with the believed optimized human adaption as represented by the high plateau people in Ethiopia. Next, why do suboscines have higher numbers in Latin America than in other places in the world were it is believed that suboscines are out competed by oscines? Timing of co-existence is believed to be an indicator, but do oscines really out compete suboscines? Metabolic theory - suboscines have restrictive tropical physiological adaptations. This was investigated by looking at summit metabolic rate. Oscines do have higher summit metabolic capacity so have a competitive advantage especially in cold environments. Next, bio-geography of some closely related Manakins. Interesting presentation of gene flow within a narrow scale in Panama which has been influenced by sea level rise in the last 2000 years. What about hummingbirds expanding winter range along the gulf coast? Huge growth of 5 species in past 20 years, probably the result of winter feeding (only found at feeders). Circum-Amazonian distribution of birds - how established, how maintained? Interesting interactions of geography and climate. Fancy tools and cool maps! Shifting to Asia, what about the impact of climate on passerine species in Malaysia and Indonesia. Do the relatedness and population size of birds on the islands relate to when the islands were formed? Hmm, data shows two splitting events instead of one. Did that happen?

For the afternoon it was all about supporting my fellow Boise State representatives. First up, my research adviser, Jay, presented the result of last years Flammulated Owl surveys. These are surveys that I will be performing starting this May. Interesting new learnings about the habitat preferences of this owl species. Eric then presented his preliminary findings about hawkwatch efficiency using a double observer method. I participated in this survey last fall as one of the hawkwatchers at Lucky Peak. Both presentations were well attended and well delivered. Alison had the late afternoon slot which decreased attendance at her presentation on the breeding preferences of Snowy Plovers in the Florida Panhandle. Her study was looking at why Plover appear not to favor engineered beaches. Lots of potential factors, but in the end it does not appear to be the engineering but the human presence which is discouraging them. She delivered a great talk.

The afternoon sessions also included a summary of Mexican Spotted Owl monitoring in Grand canyon where they have identified preferred habitats and preliminary data shows higher than expected productivity. Another talk focused on the Williamson's Sapsucker in Canada. Identifying the specific habitat structure which promotes strong productivity in the sapsucker - a specific combination of Aspen density and Ponderosa Pine density in the west, and Larch stem density in the east. A study of Snowy Plovers on the Los Angeles beaches, their native wintering beaches, has shown a number of declines and problems, primarily people. There is a common theme here. The group is investigating conservations measures that are acceptable to the human population but provide some protection for the birds. The team is gaining valuable experience in the minimum size of a protected environment and how they enable movement and provide adequate nesting materials. Tough problem.

That's the end of the sessions. Tonight is the final banquet then I fly home very early in the morning. It has been a very educational week. I definitely learned more than I would have in class. Now I have to try to catch up with those classes after missing a full week. Three exams next week. Ouch...

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