Classification of Living Things

• Biodiversity is the number and variety of species and ecosystems on Earth
• Example: a rainforest has more biodiversity than the tundra
• Biodiversity is often understood as the number of types of plants, animals and microorganisms
• The fundamental unit of biodiversity is the species
• A species consists of all organisms capable of breeding freely with each other under natural conditions
• Example: lions breed with lions; robins breed with robins
• Genetic diversity refers to the genetic variability among organisms, usually within individuals of the same species
• Example: human genetic diversity includes differences in hair, skin, and eye color
• Species diversity is a measure of diversity that considers the quantity of each species present, as well as the variety of different species present
• Example: An ecosystem with 10 species each with 500 individuals is more biologically diverse than an ecosystem with 10 species each with 50 individuals
• Structural diversity is the range of physical shapes and sizes within a habitat, critical for biodiversity as it creates microhabitats
• Example: An ecosystem with more structural diversity will have greater biodiversity
• In 2010, 1.75 million different species have been identified, with estimates ranging from 3 million to 100 million species in the world
• Human activity is accelerating the rate of extinction, estimated to be 10000 times greater than without human influence
• Species extinction is a natural process, with biologists estimating a new species becomes extinct after approximately 1 million years
• Early attempts at scientific classification involved grouping organisms into meaningful categories, with categorization becoming more specific and simplified over time
• Variation in Kingdoms:

  • In the US: Monera, Protista, Fungi, Plantae, Animalia
  • In UK and Australia: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia
• Carolus Linnaeus in the 18th Century developed binomial nomenclature for naming organisms, with a proper name consisting of Genus and Species written in italics or underlined
• Example: Ursus americanus (North American Black Bear), Ursus horribilis (Grizzly Bear), Phascolarctos cinereus (Koala Bear), Ailuropoda melanoleuca (Panda Bear)
• Taxonomy involves grouping organisms based on similar features, with taxon representing groups with similar characteristics
• Taxonomic hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, Species