Would all groups of species in an ecosystem be as easy to identify (e.g. insects)?

Question

Would all groups of species in an ecosystem be as easy to identify (e.g. insects)?

Answer 1

There is a lot of ways one can identify and categorize species in an ecosystem. One was is to look at physical features and behaviours, another more in depth way is to look at their genome and how different it is from one another. Most times it is relatively easy to distinguish species (a cat is definately different from a dog), but when species are very similar in physiology (the way they look) and behaviour (the way the act), and in genotype then things get a little complicated.

The ultimate question is, at what point does a group of individuals in a species become a new type of species. How much of a difference matters?

These questions usually arise under certain conditions that a species population may encounter. If this population is found spread over a large area, selestion pressure in different regions of this area may favor certain characteristics that other regions don't. Essentially isolating sub-groups of this population. If this population were to encounter a different species an start mating with them, then new alleles are being introduced to the gene pool where the two species meet.  

Speciation is a very dynamic process. Although in most cases people can agree that one species is one species and another is another, it is usually in areas where wild-type (normal or most popular type)  genomes are being disrupted that things get a little grey.