Weekly Reports

For me one of the most interesting subjects in the scientific world is speciation. Speciation is by definition ‘the evolutionary process by which new species arise’. Although there are different ways that a species will diverge into multiple species, there is one thing that hold true for all speciation events and that is that a new niche needs to become available. A niche is a position in an ecosystem; if you think of nature as a factory there are a multitude of machines and resources and there are positions that need to be filled by employees, if the factory diversifies and adds another component, new positions open up for new workers. Species are the workers in nature’s factory. A species can loosely be defined as a group of individuals capable of reproducing to create fertile offspring. The classification below species is a subspecies. Sometimes a species is split into sub-groups as a result of geographic variation – the individuals can still interbreed if given the opportunity, but some major obstacles, like the Rocky Mountains for example, prevents them from doing so. Prolonged isolation between the subspecies often results in them looking and sounding different for each other although they are still one species. The yellow-rumped warbler is the perfect example of this; on our side of the Rockies we have the myrtle subspecies and west of the Rockies they have Audubon’s. Myrtles and Audubon’s look quite different but they do interbreed and intergrades between the two groups can be found in a narrow strip where the two groups meet. Even as far away from the mountains as we are we see the occasional myrtle with some of the yellow throat feathers of an Audubon’s. If you are wondering if continued isolation will eventually cause subspecies to differentiate to the point of becoming distinct species, the answer is yes. Speciation is a hot-topic in the birding community and there are two main factions: the splitters and the lumpers. As their names imply, the splitters are keen on using genetic testing to tease apart every little species and subspecies conclusively whereas the lumpers are content with status-quo and feel that ‘if you can’t tell them apart by looking at ‘em, they are the same species!’ The most current and heated debate was the splitting of the winter wren species into two different species: the pacific wren and the winter wren. They look identical and sound nearly identical, but genetics have proved that the wrens on the West Coast are not like the wren of the rest of Canada. The reason I picked speciation as today’s topic has to not only with the hybrid warbler I reported on a few weeks ago but also with a yellow-bellied sapsucker that I caught the other day. North American sapsuckers used to be considered all one species with three subspecies, but in the 80’s they were split into three distinct species. There is still some debate over this since the red-naped species (west of Rockies) looks almost identical to the yellow-bellied (east of Rockies) except it has some additional red at its nape (back of head). The two species hybridize quite a bit and lots of intergrades show up – like the one I banded at one of our MAPS sites.