Selection-Evolution

Giraffe height increased over time

• Directional Selection

• Disruptive Selection

• Stabilizing Selection

• Artificial Selection

On average, human offspring are 7.2 pounds

• Directional Selection

• Stabilizing Selection

• Disruptive Selection

• Artificial Selection

Panthers had an increase in melanin over time

• Directional Selection

• Stabilizing Selection

• Disruptive Selection

• Artificial Selection

Frogs with very short toes and very long toes have an advantage

• Directional Selection

• Disruptive Selection

• Stabilizing Selection

• Artificial Selection

Snails with a forward spiral and snails with a reverse spiral have an advantage

• Directional Selecion

• Disruptive Selection

• Stabilizing Selection

• Artificial Selection

Elephants who are too large can't move efficiently and small elephants can't compete with large elephants

• Directional Selection

• Disruptive Selection

• Stabilizing Selection

• Artificial Selection

Aspen trees that are over 25 meters tend to blow over in high winds and aspen trees that are under 15 meters don't receive enough sun

• Directional Selection

• Stabilizing Selection

• Disruptive Selection

• Artificial Selection

Rhinos continue to increase in size over a long period of time

• Disruptive Selection

• Stabilizing Selection

• Artificial Selection

• Directional Selection

Bacteria that are too large can't move nutrients around efficiently and bacteria that are too small can't compete

• Directional Selection

• Stabilizing Selection

• Stabilizing Selection

• Artificial Selection

Producing 1,000 cactus spines requires too much energy but producing lower than 500 spines puts the cactus at risk of being eaten

• Directional selection

• Stabilizing Selection

• Disruptive Selection

• Artificial Selection