Why classify organisms?
• With over a million species so far identified and estimates of up to 30 million species on Earth there is a great need to organise this biodiversity. • Systematics tells us about the patterns in nature, the way organisms are related and how they evolve. • Systematics can be used to identify organisms, which are important to us. Useful organisms which could be sources of materials for us (e.g. pharmaceuticals). Harmful organisms which may cause disease in ourselves or in livestock and crops. The unit of taxonomy: The SPECIES. It has biological significance: Species form populations of individuals which may interbreed to form fully fertile offspring. Problem: Some species only use asexual reproduction or rarely use sexual reproduction. Taxonomists compare a new specimen with given characteristics: morphology, anatomy, behaviour, embryology, protein structure, karyotypes, DNA sequence (DNA fingerprints). The binomial system of classification Species are grouped by levels of relationship
