Sunday, January 18, 2015

strange familiar birds

Their beaks are brown for winter, their plumage blurry with stars. They convene on the sidewalk for a brief bird-minute, and I stare at them as if I will be able to see urban evolution in action. I haven’t seen it yet, but I know that it is there; in their genes, in their bones, and in that walk - that rises and falls with a graceless bounding pride. What can we learn from these strange familiar birds?

The concept for this project grew out of a basic evolutionary question I had about how populations evolve. We know that a dramatic and prolonged decrease in population size results in lower genetic diversity, and stronger genetic drift 
for succeeding generations. But what happens to morphology under these conditions? I don’t think there is one answer for all taxa. Variation differs from species to species, and from trait to trait. Because of the stunning history of starlings in our country, I am deeply curious about the diversity of their skeletons, feathers and beaks. By bringing a cage full of lively birds from England to the US and releasing them in Central Park, an accidental evolutionary experiment began in the winter of 1890 - one that we are following up on today.

The data are coming in. Our sturnus vulgaris mitochondrial DNA sequences look clean and strong. One goal of our project is to better understand the genetic diversity of North American (NA) starlings, and compare that to other sturnus vulgaris populations around the globe. The expectation is that genetic diversity will be low in NA starlings because of the small size of their founding population (60 individuals in 1890), and their rapid expansion (to 200,000,000 in just 125 years). It is too early to tell how much, or how little variation, we have yet. I am highly hopeful that we will get solid results this year. We are lucky to have the great help of wildlife authorities throughout the country for suppling birds. And I am working together with two conscientious students who are doing careful lab work. We have started a database for recording information about each specimen. It is exciting to see it grow. Data accumulation is one of the great thrills of doing science, it’s work made visible.

No comments:

Post a Comment