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August 30, 2013

Charles Darwin and Casuarina

WorldCat, which lists the holdings of libraries all over the world, is now claiming that several hundred libraries have my book, Darwinian Agriculture. Many of these appear to be "electronic access", which won't accelerate the availability of the paperback, but that still seems like a lot.

Among the libraries on the current list are those at Epic Bible College -- what a great name! -- and at Charles Darwin University. Another great name, and it gets better. It's near Darwin, Australia, but actually located in the town of Casuarina, which is named for one of my favorite trees. Casuarina is:

* A nitrogen fixer that isn't a legume.
* A flowering plant that looks like a conifer.
* So salt-tolerant I've seen it growing a few meters from the ocean, on Heron Island.
CasuarinaBranch.JPG

August 20, 2013

NPR's Krulwich celebrates his ignorance

As a long-time supporter of National Public Radio, I was disappointed by Robert Krulwich's incorrect claim that "we don't know" why it took so long for single-celled life to "join with another" and become multicellular.

Multicellularity probably didn't evolve that way. When we exposed unicellular yeast to selection for larger size, clusters descended from single cells (reproducing but not separating) out-competed clusters formed by single cells coming together.

As for why it apparently took so long, the simplest explanations are:
1) multicellularity requires so many simultaneous mutations that the combination only arises every billion years or so, or
2) during the first 2-3 billion years of life on earth, conditions were such that there was little or no benefit to multicellularity.

Our experimental results favor the second hypothesis. With strong selection, simple multicellularity evolved in less than a month from unicellular yeast and in less than a year in other species (not yet published).

August 2, 2013

Carnival of Evolution

Lots of interesting links at Joachim Dagg's Ecology and Evolution Footnotes.

August 1, 2013

Ediacaran Fossils at Mistaken Point, Newfoundland

Plan ahead if you want to see these 500-million-year old fossils!

Access to the Mistaken Point Ecological Reserve is limited to guided tours, which are free and very informative, but can fill up. Call at least a few days ahead. We only had one full day in Newfoundland and the tour was fully booked that day. Fortunately, someone cancelled.
MistakenPointFossils.jpg HumpbackWhaleBackCloseup.jpg

The tour starts at the Edge of Avalon Interpretive Center and is led by Julie Cappleman. The center has a huge cast of some of the fossils and is hoping to display more, if they get World Heritage Site status. The "fossils" are impressions left by soft-bodied species, rather than mineralized bones or shells, so the cast is an impression of an impression. But it's an excellent copy. You can see even more detail in the cast than on the field tour, although I enjoyed seeing the fossils in situ. The cast was made by Research Casting International, run by Peter May. His son, Alex May, who spent a year in my lab working on rhizobia, first told me about Mistaken Point.
MistakenPointFossilCastJulie2.jpg
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The tour was great! Between driving to the trail head, a pleasant and interesting 2-km hike to the coast, viewing the fossils and return, we were there from 1 PM to a bit after 4. You can't get close enough to touch most of the fossils, but Julie lent us binoculars for a good close-up view, while her assistant pointed out some of the more interesting fossils. We did get one closeup view of fossils near the trail. There was a lot of morphological diversity in these early representatives of multicellular life.

The previous day, we went on the Gatherall's boat tour and saw humpback whales and puffins. We stayed at Elaine's Bed and Breakfast and got a good look at a minke whale in the bay, while we were eating breakfast. But I'll let a humpback have the last word.
MistakenPointFossilCloseup.jpg
HumbackWhaleDivingCloseup.jpg