Friday, April 5, 2013

Biogeography And Teaching Evolution

Joshua Rosenau of the National Center for Science Education, Oakland, CA, USA has a wonderful essay in Evolution: Education and Outreach on how observations of the bio-geographic distribution of species helped Darwin and Wallace to work out independently their theories of evolution through natural selection.

He suggests that many of  today' students who are often reluctant to accept evolution because they see differences between species as unbridgeable gaps can overcome this obstacle by observing the actual patterns of differences between closely related species living amongst them.

From the article:

The greatest challenge many students face in understanding evolution is what Wallace faced in 1846: they haven’t seen the sort of diversity that calls for explanation in terms of evolution. The world most students encounter seems to contain organisms in discrete categories: squirrels and rabbits, robins and sparrows, grass and daisies, oaks and pines. They are unlikely to notice that two ladybird beetles actually represent different species or that there are several species of grass in their lawn, let alone to recognize that there are two local species of chipmunk which can only be distinguished by dissection or DNA analysis. What diversity they notice represents groups that are quite distinct, with differences so large that it is impossible to imagine how their members could share a common ancestry.

As a result, students today, much like Darwin in 1835, tend to see species as distinct entities. Presenting students with a similar experience of the often subtle differences between species can similarly shake this misconception. When they realize how low the barriers can be between different species, they can place lessons on speciation in a more accurate context. Rather than imagining that speciation means turning lions into tigers, or bears into cows, or fish into humans, they will see that speciation involves a subtle divergence in the evolutionary trajectories taken by populations. Because the Gal√°pagos mockingbirds were still early in their divergence, Darwin was able to recognize the process. Students today can learn similar lessons by examining the subtle differences between species on neighboring islands. The Evolution and Nature of Science Institute has a lesson plan in which students compare lizards in the Canary Islands (, while Understanding Evolution offers a lesson plan looking at Anolis lizard biogeography in the Caribbean (

Very relevant advice but applicable only to those students who are willing to examine the evidence with an open mind. People indoctrinated with a fundamentalist ideology are unlikely to be impressed by two very similar species of beetles in their backyard. .

By the way this journal,  Evolution: Education and Outreach is now open access.

So dip into it.

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