Evolution in action
Fascinating article on speciation on BBC news at the moment. It’s about how separate species actually form, something which I’d never really thought about before.
As you probably know, the basic idea of Darwinian evolution is that with each generation, random mutations or interesting combinations of genes give the individuals different abilities. Those with the best abilities are most likely to survive and breed, hence passing on their abilities to the next generation. In this way, eyes gradually develop from small llight sensitive cells to the amazing things we have today.
But if evolution is always moving forward, why do we end up with different species? Different enviornments is of course important - like fish moving onto the land to avoid the competition from other fish. Or, if you get two groups of animals separated (by say a river, mountains, etc) then each undergoes their own random changes, and develop differently. When they finally meet up, they might no longer be able to breed.
But what about species of, say, butterflies? They all eat the same thing (basically), live in the same places, etc. So why should they end up as different species which can’t interbreed - why not just one species, the best, winner takes all?
What researchers have found is that when closely related species of a certain type of butterfly live nearby, they develop different markings and tend to mateonly with those butterflies who have the “right” type of markings (i.e., of their species). It seems that mating with closely related butterflies produces strong offsprings, whereas mating with close species, although possible, produces weedier offspring that are less likely to survive. In this way, they can concentrate their gene line, and eventually become two separate species!
The article has quite a bit more detail, and is very readable, so go and check it out for more details.