discourse on species ecology
We don't have to be able to say exactly where/when a transition between two species occurs to identify the separate entities, we only need to know that there is some transitional gradient or point, beyond which we have switched from one entity to the other. That is the concept of species. In fact, that is the nature of most ecological concepts.
Like I said, most of ecology is based on things that have fuzzy boundaries. Above all else, ecology teaches us that the natural world is interconnected in more complex ways than we can even imagine. If the requirement for a natural entity is that there must be perfect boundaries between one entity and the next, then much of what we measure in ecology is imaginary. I agree that species are messy things to determine because in many cases we can't say precisely when one species transitions to another. And because of that, there will always be arguments about where those lines should be drawn. But that doesn't make the phenomena that organisms tend to segregate gene pools into units we call species not real.
Not being perfect is not the same thing as not being good.
The species concept has been modified for a long time. Linnaeus thought
species were immutable. Several scholars said they were transmutable.
Darwin showed us the mechanism that caused transmutation over space and
time. Mendel showed us the patterns of inheritance that explained the
natural variation within species that puzzled Darwin. Through all of this
the species concept has been modified to reflect our growing knowledge.
When Watson and Crick revealed the structure of DNA, they brought us the
molecular age leading to our being able to read the genetic code directly.
Sure, this has created many surprises and we know that in many cases species
lines are even more blurry than previously known. But much of what
molecular biology reveals actually supports the species concept.
We would depend on the same system of evidence, argument, and consensus that
we have now. Unless some wild revelation comes along, that's the way it
will be.
Brent Brock
In nature there is no such 'transition'. There are no species. Populations, however, change their genetic setup the whole time.
Lars Osterdahl
Chorus:18-19 April 2010