There are three main types of natural selection: stabilizing selection, directional selection, and disruptive selection. Stabilizing selection favors average traits so that medium-sized or medium-weight individuals are most likely to survive. Directional selection favors individuals with one extreme trait, like long-necked giraffes or large horses. Disruptive selection favors individuals with opposite extreme traits, so average or intermediate individuals die out while the extremes survive, like with camouflaged light or dark rabbits.

1. Types of Selection(Stabilizing, Directional, Disruptive)

2. Natural SelectionAnimals adapting to environmentAdvantaged animals survive and reproduce

3. Stabilizing SelectionMost CommonAverage survives

4. Stabilizing SelectionExamples:Short flowers die: No sunlightMedium flowers live: Perfect conditionsTall Flowers die: Wind damageLightweight babies have higher mortality rate: weakerAverage weight babies survive more often: healthyHeavyweight babies have higher mortality rate: when being born

5. Directional SelectionOne extreme trait is favoured

6. Directional SelectionExamples…A long time ago…Short neck giraffes died: could not reach leaves on treeMedium neck giraffes died: could not reach leaves on treeLong neck giraffes prospered: leaves were reachableA long time ago…Small horses died: very disadvantageousMedium horses died: disadvantageousLarge horses prospered: advantageous

7. Disruptive SelectionOpposite extreme traits are favouredAverage trait is eliminated

8. Disruptive SelectionExamples…In an environment with black and white rocks…White rabbit lives: CamouflagedGrey rabbit dies: Seen by predatorBlack rabbit lives: CamouflagedIn an environment with deep and shallow flowers…Short beak hummingbird lives: can get pollen from flowerMedium beak hummingbird dies: cannot get pollen from flowerLong beak hummingbird lives: can get pollen from flower

9. Video on Types of Selection

11. Works Cited