The Atavism has some thoughts on speciation in response to a high school teacher’s query. He uses the following nice diagram to indicate what some of the core species definitions mean:
It’s neat, and therefore… wrong. By which I mean that given the rule that biological organisms do what they damned well please, sometimes speciation will not involve allele frequency change (but rather reorganisation of the same alleles), and sometimes the new species won’t occupy a distinct niche, and sometimes hybrids remain viable, and sometimes different species do not have “monophyletic DNA” (which I take to be the claim that some of the DNA is unique to that species). Life is unkind … to taxonomists.
Hi John,
You are of course right. I should have been more explicit that this is an example of what might happen in one case not ‘the one true path to speciation’ – if you find a universal truth in biology you are almost certainly wrong
The idea was to highlight De Queiroz’s ideas about species concepts as species delimination concepts.
(And yes “monophyletic DNA” was my shorthand for species having completely sorted lineages for at least one gene)
Don’t get me wrong – I like the diagram. I was just making a passing observation. It has to do with essentialist definitions failing in biology.
I strongly recommend Speciation By Jerry A. Coyne, H. Allen Orr. It will provide a more technical discussion of the various ways that it can happen, along with some aspects of the way the word means different things in different contexts, and really nothing at all when you look to closely.