Micro Life Zone
Asked by pnemonoultramicroscopicsillicovolcanoconiosis to Arti, Chris, Dustin, James, Steven on 21 May 2012.
Keywords: species, subspecies
Interesting question. Humans like to categorise things and most science starts out as classification. If you can’t explain something, count stuff and give groups of things names. So, we have species, sub-species, varieties, orders, kingdoms etc etc when it comes to categorising life on Earth. But these are just names that roughly describe the genetic separation between organisms. The theory of evolution is perhaps my favourite scientific theory because it is so intuitive and elegant. It basically states that if a niche exists for life, a form of life will evolve to fill it. That is the life form evolves in order to take advantage of the environment, and the individuals most successful in doing this have the best chance of passing on their genes, hence propagating the characteristics that allow the exploitation. Evolution is continuous but is generally supposed to be slow, with a continuum of outcomes. We choose to place a border at some point and assign some outcomes the label of subspecies or another label.
As Steven has said, we like to put things into categories. While most of the classification is arbitrary, meaning we just put it in a place that seems to make sense, species are real provided you provide a spatial and temporal context. That is you have to refer to a species by it location and time period.
Depending on what sort of question a researcher is asking, may alter the way they interpret a species. But the generally accepted definition of a species is that “a species is a naturally occurring interbreeding population that produces viable offspring with no loss of fecundity (ability to reproduce)”.
So what about a subspecies? Well you can never have one subspecies of a species, it has to be two or more in the species group in order to have a subspecies, it wouldn’t make sense otherwise. Often the case with subspecies is that their geographic ranges overlap, and so there are two semi-distinct populations, with some interbreeding in a hybrid zone.
A good example of this is the carpet python species of Australia. Diamond pythons are referred to as Morelia spilota spilota and they occupy the east coast from the Victorian border up to about the QLD border. Coastal carpet pythons are Morelia spilota mcdowelli, and they occupy from northern QLD down to the NSW border. Around the border area these two subspecies interbreed in what is referred to as a hybrid zone, and the two extremes are consider subspecies.
These classifications though will often change as taxonomists change the way they define the species and the sub-species. To someone like me, in many senses I do not care much for the label we put on an organism, I am more interested in what it does in that environment.
Nice answers by Steven and Dustin.
Pnemo, people really do love to categorise things. The classification system is pretty fluid and does change quite a bit (even at the Kingdom level), as people discover new organisms, and also more similarities and differences between different organisms. Sometimes organisms that are categorised as subspecies at one time eventually become classified as separate species later on, if they are no longer interacting in a hybrid zone and become distinct enough that, if they do interbreed, their offspring can no longer reproduce.
Great question and well handled by the others
By BRIDGE8 under license from Mangorolla CIC 2020