Courtship & Ancestry
Biology: IB Diploma Higher Level, topic 4.1.3
Courtship Behaviour
Species are defined as two organisms that can interbreed to produce fertile offspring. Courtship behaviour is an important factor to consider when classifying species.
Mating
- Organisms within the same species can mate to produce fertile offspring.
- It is important that organisms only breed with individuals of the same species so that they can pass their genes to their offspring.
Identifying mates
- Potential mates of the same species can be identified through courtship behaviours.
- Courtship behaviours are complex displays that help an individual attract a mate.
- E.g. The male superb bird of paradise spreads its wing and dances to attract a female.
Species-specific
- Courtship behaviours are useful when classifying species because they are species-specific.
- Individuals of the same species will do the same courtship behaviour.
- Only individuals within the same species will respond to the courtship behaviour.
- And so, courtship behaviours are a useful tool for classifying species.
E.g. Peacocks
- Peacocks have beautiful patterns on their tails.
- The peacocks display their tails to females (peahens) to attract a mate.
- Only male peacocks have this specific pattern on the tail and only female peahens will respond to this pattern.
Phylogeny
Phylogenies are used to understand the evolutionary relationships between organisms. Phylogenies can help classify organisms.
Shared ancestry
- The evolutionary relationship of an organism or group of organisms is called its phylogeny.
- Phylogenies are based on the fact that all organisms share a common ancestor.
- More closely related organisms will share a more recent common ancestor than more distantly related organisms.
Phylogenetic tree
- A phylogenetic tree shows the evolutionary relationship between different species and their most recent common ancestor.
- Each branch on a phylogenetic tree shows a different species.
- The point that two branches join together is the common ancestor of the two species.
Test yourself on Courtship & Ancestry
Which of the following statements about courtship behaviours are true?
Why are courtship behaviours useful when classifying species?
In a phylogenetic tree, what does the point where two branches join represent?
Which of the following statements about phylogeny are true?