Why Don't We Celebrate New Species?

I have previously linked to Olivia Judson's New York Times column called "The Wild Side". Her column is always illuminating and written with an infectious enthusiasm for the incredible variety of life on our planet. It is unfailingly lucid in explaining concepts in evolutionary biology in clear and concise prose. The column today is called "All Hail the Apple Maggot" and discusses a wonderful example of how a new species gets created from an existing one (including a great little primer on the definition of species). She also reflects on why we tend to more easily focus on lamenting extinction of species as opposed to celebrating the creation of new ones.

There is an unending stream of misinformation and outright lies being churned out on the topic of evolution and natural selection (see Zakintosh's blog post on November 17th called "The CREaTIoNist" for another unfortunate example; a supposedly scientific book by the Turkish author Harun Yahya). Given the constant hostility toward this scientifically sound but revolutionary principle I always like to link to good writing on evolution for laypeople so that at least anyone reading this blog can gain access to credible writing on the subject.

The appearance of a new species is not so dramatic. The first members of a new species will typically be indistinguishable — to us — from the species they have evolved from. And while extinction has a clear final moment — the last member of a species dies — the formation of a new species does not usually happen in a single recognizable instant. Which is why we haven’t yet raised our glasses to celebrate, say, Rhagoletis pomonella, the apple maggot fly.

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The most common way to define a species is a group of individuals that breed with each other successfully. For example, dogs, despite their vastly different looks, can breed with each other, so they are are considered one species. Horses and donkeys are counted as different species because their offspring (mules and hinnies) are sterile. For individuals to be considered as belonging to separate species thus means that they are “reproductively isolated”: they can’t, won’t, or don’t breed with each other.

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I can sense your excitement. And perhaps that’s the real reason we don’t celebrate apple maggots, or any of the other new species (and there are many we know about) that are in the process of evolving. For when a new species does appear, it’s just not that different from the old species. To evolve the flamboyant differences that distinguish a swan from a duck, or a human from a chimpanzee — that takes thousands, even millions, of years.
That is what we lose with extinction.

Photograph: Rhagoletis pomonella, the apple maggot fly. (Wikimedia
Commons)