Which came first?

Which came first, the chicken or the egg?

Answer 1 (to emphasize the value of descriptiveness over brevity): Obviously, the egg came first. Current knowledge dates the domestication of the chicken at no earlier than 10,000 years ago, while reptiles pioneered the hard-shelled egg idea about 300,000,000 years ago when they diverged evolutionarily from Paleozoic amphibians (Carroll, Robert L. “Problems of the Origin of Reptiles”Biol. Rev. 1969, 44, pp. 393-432).

Let’s rephrase the question:

Which came first, the chicken or the chicken egg?

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Save the (empty) rainforests

Today, I am going to challenge the way you think about habitat. A habitat is the place where an animal or plant or other organism lives, like tigers in the jungle, poison ivy in areas of forest floor with generally poor soil, and archaea in the hot springs at Yellowstone National Park and in the rumens of cows. Well, most of the time that’s what it is. There is an important biological exception: metapopulations.

A metapopulation is a group of organisms of the same species that occupies discrete patches of suitable habitat within a continuous range, but which is considered to be a single population because individuals migrate from patch to patch within their lifetimes.

metapopulation

The range of a metapopulation (dotted line) encompasses many patches of suitable habitat (shaded areas).

migration

Organisms can migrate among the patches during their lifetimes.

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Why I wear my lab coat

I work with a soil bacterium, Myxococcus xanthus. All of the safety procedures my lab employs are designed not to protect us from it but rather to protect it from, well, everything. We don’t wear gloves, we don’t use goggles, there’s no strict wash-your-hands-before-you-leave-the-lab policy, and most of us don’t wear lab coats.

There really isn’t a point to wearing a lab coat when you work in an environment where you are the most dangerous thing around. Maybe you’d want it on media-making day if you’re a bit clumsy or if you forgot that it was media-making day and accidentally wore nice clothes, but except for protecting you from agar spills, the coat doesn’t do much.

Physically.

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