“So how does that work? How do you get a bunch of books or whatever into DNA format?” –my Dad
A recent article my Dad read in The Atlantic ("Fun with DNA") about DNA spurred an interesting conversation about the state of genetics, our knowledge of DNA, and even more so, about the depth of (mis)understanding between the scientists and the public.
In reading Marks’ recent post on “New Conservation”, I was struck by some of his closing remarks. In particular, “The majority of people now live in urban environments. With this recognition, there has been a rapidly evolving appreciation for the degree to which these urban populations are disconnected from nature and the importance of a connection to nature to support conservation actions. What do we do in urban environments with respect to conserving nature?”
What is a sensitive species? A dictionary definition of sensitive is “quick to detect or respond to slight changes, signals, or influences.” According to Merriam-Webster, the definition of tolerant/tolerance is “the ability to accept, endure, experience, or survive something harmful or unpleasant”. So what makes a species or group of species such as amphibians, which are now currently considered “sensitive”, actually sensitive? Amphibians are listed as sensitive in many documents, for example, the US Forest Service defines sensitive species as “species that need special management to maintain and improve their status on National Forests and Grasslands, and prevent a need to list them under the Endangered Species Act (ESA)”. But the question should be, what are these organisms “sensitive” to? Amphibians have been around a long time (hundreds of millions of years!) and are surprisingly tolerant and resilient; some species of amphibians can freeze solid!
To really get a sense of this, let’s talk about extremes. Amphibians were of particular interest to early physiologists because of their unusual respiratory and metabolic adaptations. This led to some rather remarkable experiments. For example to determine if respiration could occur via the skin, physiologist W. F. Edwards removed lungs from frogs and found they could survive in cold water saturated with air for over a month (Edwards 1824). In another experiment a geologist (William Buckland) encased toads in sandstone and limestone chambers and buried them for a year to see how long they would survive*. Those in the more porous limestone survived the first year; the others did not (Buckland 1832). Other experiments involved coating frogs in paint or oil to see how it affected respiration (Edwards 1824, Wells 2007). We now have a better understanding of many amphibian adaptations, including their very low metabolism, and the ability to respire and hydrate through their skin, which makes them both resilient and sensitive (according to the dictionary definition) in a wide range of environments.
Macabre examples aside, the point is amphibians possess amazing adaptations that make them quite hardy organisms. We tend to think of them as “sensitive” without understanding they represent 360 million years of successful adaptation. Diversifying around the Devonian extinction event, amphibians successfully weathered the next three major global extinction events (ending the Permian, Triassic and Cretaceous). They are finely tuned to the ecosystems in which they persist, often with amazing resilience to very dynamic environments; from deserts to tropical rainforests to artic conditions where they can freeze solid (I am certainly sensitive to freezing solid). This close link means amphibians are both sensitive and tolerant to changes in their environment (according to the dictionary definition).
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