This bird is evolving in a very weird way

[n2doc]

An acorn-eating island scrub jay. Another population of the species specializes in attacking pine cones, and accordingly has a differently shaped bill. Katie Langin

THE SCRUB JAYS of California’s Santa Cruz Island really love a good peanut. “It’s like crack to them,” says Katie Langin, a biologist at Colorado State University who probably knows these birds better than anyone else. Working with Scott Morrison of the Nature Conservancy, Langin started visiting the peaks and valleys of this wild island in 2007, baiting jays with nuts to trap and tag them for her dissertation. Before she came along, what researchers knew about the island scrub jay came from observations in just a handful of places. Much of this rock is inaccessible, but Langin had a helicopter.

As she gathered more and more data on different populations of the birds around the island, Langin had a revelation: The birds, members of one single species, had split into two varieties in different habitats. Island scrub jays living in oak forests have shorter bills, good for cracking acorns. Their counterparts in pine forests have longer bills, which seem better adapted to prying open pine cones. That may not appear to be something you’d consider a “revelation,” but it really is—if you believe in evolution. Ever since Darwin and his famous finches, biologists have thought that in order for a species to diverge into two new species, the two populations had to be physically isolated. Those finches, for instance, each live on a different Galapagos island, where their special circumstances have resulted in specialized bill shapes. Yet the two varieties of island scrub jay (they haven’t technically speciated—yet) live on the same tiny island. If they wanted to meet each other for a brunch of acorns and/or pine nuts and perhaps later some mating, they could just fly right over.

This is very, very weird. It’s an affront to a sacred tenet of evolution you probably learned in school: Isolation drives speciation. Well, speciation can also come about in a broadly distributed population, with individuals at one end evolving differently than individuals at the other, but nothing kicks evolution into overdrive quite like separation. Without it, two varieties should regularly breed and homogenize, canceling out something like different bill shapes (though rarely the two types of island scrub jay will in fact interbreed). And the island scrub jay isn’t alone in its evolutionary bizarreness. In the past decade, scientists have found more and more species that have diverged without isolation. Langin’s discovery with island scrub jays, published last week in the journal Evolution, is perhaps the most dramatic illustration of this yet.



more

http://www.wired.com/2015/03/jay-evolving-weird-way/

[phantom power]

1. geography is an overly narrow view of "isolation"

Lots of things can cause isolation. Behaviors, diet, etc.

[Panich52]

4. Geo-separation doesn't have to be major, either

Isolation for some species could be caused by something as simple as a road built thru a forest, or cutting old-growth trees and thereby separating crown ecosystem into two.

[dixiegrrrrl]

2. We have blue jays here, and lots of pine trees.

amazing number of pine trees, actually. They are a commercial crop.
Wonder if the jays here eat the acorns or the pine cones?
or
both??

[GeorgeGist]

3. Like jockeys ...

and basketball players.

[Plucketeer]

5. We have Scrub jays here in central California

They DO love peanuts - any kinda nuts really. We live amidst commercial groves of walnuts. Under dead leaves, at the base of weeds or grasses, even under boards or other stuff that lays about - there's walnuts hidden away for later.

When we lived in the LA basin years ago, we had a Scrub jay we named Peanut. We'd see him on our porch, trying vainly to figure how to get to the jar of peanuts we kept on a table by the sliding door. One day I left the door open and with just a bit of caution, Peanut helped himself to the bounty. Then for fun we started setting peanuts on various tables and counters thru our home. Peanut caught on fast. Before long he'd come in, check us out and then fly to the other end of our home in search of the prize - his peanut. He was a blast to watch. I had to start setting that jar somewhere else or Peanut would sit on the porch and beg to be let in. Every hanging and decorative pot we had in our yard was stuffed with peanuts that this flying pack rat would stash against the future!