4.5 Species and taxonomy

What is a species?

A group of organisms that can interbreed to produce a fertile offspring

Why cant two different species produce a fertile offspring?

• Different species have different chromosome numbers so offspring might have an odd chromosome number

• Homologous pairs can’t form and meiosis cant occur to produce gametes

How does courtship behaviour result in successful mating?

• Allows recognition of the same species so fertile offspring produced

• Allows attraction of the opposite sex

Describe a phylogenetic classification system

Species arranged into groups called taxa based on their evolutionary origins and relationships

Uses a hierarchy - smaller groups placed within larger groups, no overlap between groups

Name the taxa in the hierarchy of classification

Domain → kingdom → phylum → class → order → family → genus → species

How is each species universally identified?

By a binomial consisting of the name of its genus and species (eg homo sapiens)

What is an advantage of binomial naming of species?

It is universal so there’s no confusing as many organisms have more than one common name

What two advantages have helped clarify evolutionary relationships between organisms?

Advantages in genome sequencing → allows comparison of DNA base sequences

Advances in immunology → allows comparison of protein tertiary structure