Lecture 7 - Phenotypic evolution Flashcards
How have humans harnessed evolution?
Through selective breeding
Allowed us to feed the world
Also have used for pets to make dogs
Quantitative traits
Traits that vary continiously
e.g. height, blood pressure and plumage colour
Quantitative genetics
Study of how quantitative traits are inherited and how they evolve
Phenotypic variance
Variance in a population for a particular trait
What explains phenotypic distributions?
Genes and the environment
Phenotypic plasticity
The capacity of an organism to develop any of several phenotypic states depending on the environment
Example of inducible defences of Crucian carp
With no exposure to predator cues the body shape is shallow which gives a competative advantages in the abscence of predators as more streamlined
With exposure to predator cues changes body shape to a deeper body shape, hey can attain higher speed, acceleration and turning rate. Also harder to be eaten
Reaction norms
Range of phenotypes expressed by a genotype along a range of environments
Why did lizards develop horns?
Birds capture lizards and put them on trees and fences to show off to mates
However the larger the horns the less this occurs
What are the 4 different types of selection outcomes?
Directional
Diversifying
Stabalising
Correlational
Directional selection
Selection towards a particular trait
Example of directional selection?
Finch
There was a major draught causing only large seeds to be available
ONly birds with large beaks could eat the large seeds
Powerful selection event
Diversifying selection
Extreme traits are selected for
Example of diversifying selection
Beaks in birds
Small beaks specialised in smaller food items and large beaks specialise in larger food items
Stabilizing selection
Selection towards the mean
