What does the rest of the hierarchy look like?
Taxonomy refers to the classification of living things by giving unique names to each species, and creating a hierarchy based on evolutionary descent. This is a challenging task, as most species that have ever lived on this planet are now extinct, and many more alive today have yet to be discovered and classified.
In order to achieve the above, though, we need a definition for both species and hierarchy. In the old days, a species was known as a collection of individuals similar enough in resemblance to be put in the same box. This was purely based on physical features. Today we know that similar physical characteristics on their own aren’t enough to define a species.
A species is defined in terms of observable physical features as well as the ability to produce fertile offspring.
What is courtship behaviour? The acts it encompasses are as varied as life itself; a sound, a gesture, an action, etc. The overarching and general attribute all these behaviours have (which makes them courtship) is whether they appear to be connected to successful mating.
The first feature of courtship behaviour is that it enables organisms to identify members of their own species. The central part of the definition of a species is the members’ ability to produce viable offspring. Hence, attempting to mate with members of a different species is not an advantageous behavioural trait in the context of reproductive success.
Courtship behaviours also allow organisms to approach one another without aggression or invasion of their personal space.
Sometimes the outcome of courtship behaviour is the formation of a pair bond. This bond results in a better reproductive success, due to the increased survival probability of the offspring. In some species this is the case, while in others it isn’t. This is tightly related to a specific organism’s physiology. Fish are able to lay a huge number of eggs, while pigeons only lay one or two. Therefore, it is more likely that pigeons would from a pair bond, rather than fish.
Last, but by no means least, is the nature of courtship behaviour which makes it a tool for sexual selection. This is not a mere test of survival (natural selection takes care of that), but a test of relative superiority in a variety of attributes which vary between species, at different times, and even between individual organisms. These attributes can be anything, and in many cases they seem random or peculiar. In others, they seem very much expected.
This is Hercules, the liger. Hercules has a lion father and a tiger mother. Does that mean tigers and lions are really one species? This is one example of the issues surrounding both the definition of species, and taxonomy generally.
What is a hierarchy? A hierarchy, put simply, is a system of..