Evolution doesn't really have anything to do with religion, except that many people decide that it doesn't mesh with theirs and they deny it is real without ever learning how it works. It is really a shame because many religious people do believe in evolution. It seems totally reasonable to me to believe in both and I wish more believers would be willing to follow the evidence where it leads.
I have never studied evolution formally, but I do find in fascinating and read about it now and then. Some of the things I read about are really cool and I thought it would be fun to describe them here. Hopefully I will get all of the important details right, but as I said I have never studied this formally so I might make mistakes. If I do please point it out.
Today I want to talk about ring species. Before I get into why I think ring species are so cool, I want to talk a little bit about speciation. There are a few different ways that speciation can occur, but I want to talk about something that was described in "On the Origin of Species" (It might have been "The Selfish Gene", I read them at around the same time a few years ago).
Let's say you have some type animal who lives in one particular place, let's just say it is all the way to the west of a large land mass. This animal is doing very well and starts spreading out over new territory to the east. Even though the animal is all over the place on this land mass, the animals to the far west and the animals to the far east do not breed with one another. There is breeding all through the continent, so there is some gene transfer, but generally the animals from the west and east can have separate genes and the ones in the middle are hybrids.
Now, let's suppose there is some kind of selection pressure which is different east and west. Eventually you might get animals well suited for the east and other animals well suited for the west and the in between animals wouldn't really fit well in either setting and will eventually die off, giving you two separate species.
I remember when I first read this little hypothetical story I wasn't really sure what to make of it. It seemed to make sense well enough I guess, but I wasn't sure I completely followed why the genes from one side wouldn't just propagate to the other and it didn't really make sense why the middle species would die. For the first thing, I think I wasn't thinking of a large enough land mass, and the second, there are a huge number of reasons why a population of animals might die.
So anyway, I had this situation sitting in the back of my mind somewhere, and then I read about ring species, which seem to be this process in the middle of happening, but there is also a twist, the extremes live in the same place (or maybe just nearly the same place?). Let's say you have a species that lives in a mountain surrounded by a valley, such as this salamander. As we go along the mountain range around the valley there are different populations of the animal. Any two adjacent populations can interbreed no problem, but the populations from the beginning and end cannot interbreed.
This is really cool for a couple of reasons.
1. Are the salamanders the same species or not? They can't interbreed so we should say no. However, there are 19 populations of the things that can each interbreed. So population 1 and 2 are the same species, pop 2 and 3 are the same, etc, but then pop 1 and 19 are not the same. The point is, our definition of species is a little fuzzy.
2. Suppose a bunch of the middle populations died out before we thought to look for it (say populations 4-17). We would just see 2 separate species of salamander in the same place and not think too much about it. This is a really neat demonstration of how new species could form.
That was fun. I hope I got most of the details correct here. At the very least, I hope it is clear why I think ring species are so cool.