Saturday, October 26, 2013

Bees the Time of Dinosaurs

Did Bees Die and Reach extinction at the same time that Dinosaurs did?

We know that Dinosaurs reached the end of their life cycle 65 million years ago. The havoc on Earth was monumental. And there was a lot of physical evidence to support that claim and scientific observation.
But was that the only species that went extinct at that time?

Perhaps not because some scientists like Sandra Rehan, an assistant professor of biological sciences at University of New Hampshire, and Michael Schwarz at Australia's Flinders University and Remko Leys at the South Australia Museum worked to model a mass extinction in the  bee group Xylocopinae, or carpenter bees.  The extinction occurred at the end of the Cretaceous and beginning of the Paleogene eras, otherwise known as the K-T boundary.

Molecular phylogenetics

Rehan and colleagues overcame the lack of fossil evidence for bees with a technique called molecular phylogenetics. What is that study? For starters, It is the study of organisms on a molecular level to gather information about the phylogenetic relationships between different organisms.

What this accomplishes is that this program maps out the evolutionary history of an organism or group of organisms. The end result is that scientists can be precise about their estimates  involving when various events in evolutionary history occurred.

How it works

This science branch relies on the fact that genetic change is a constant. In effect in each generation, they note that organisms change slightly, but the rate of change tends to be constant and reliable. So now scientists can compare genetic information between different species and determine when they diverged from each other by examining their degree of similarity and dissimilarity. This is important because now researchers can also use this information to construct an evolutionary timeline.

The Bees

How many species of carpenter bees were they looking through? Answer:230.  So the scientists began to analyze DNA sequences of four "tribes" of species of carpenter bees from every continent with the exception of Antarctica. They were looking for evolutionary relationships and connections. The result was that they observed patterns consistent with a mass extinction. Then by combining the fossil records with the DNA analysis, they managed to introduce time into the equation, and it yielded information not only how the bees are related but also how old they were.

So what did they learn?

With the four groups of bees in the fold the data showed the research scientists that something major was happening to these different groups of bees at the same time. Moreover, it happened to be the same time as the dinosaurs went extinct.

The end result is that if Bees went down in that time frame, what other species might have reached an extinction point? ...In process....

  1. Sandra M. Rehan, Remko Leys, Michael P. Schwarz. First Evidence for a Massive Extinction Event Affecting Bees Close to the K-T BoundaryPLoS ONE, 2013; 8 (10): e76683 DOI: 10.1371/journal.pone.0076683

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