Evolution of Stickleback Fish

The video explores the evolution of the three-spine stickleback fish, focusing on their adaptation to freshwater environments after the last glacial period. It highlights the genetic changes, particularly the role of the pitx1 gene, that allowed these fish to lose their pelvic spines, a trait that was disadvantageous in certain environments. The video also discusses the broader implications of these findings for understanding evolutionary processes and genetic regulation in animals.

What event led to the isolation of stickleback fish in freshwater lakes?

• Volcanic eruptions

• Tsunamis

• Receding ice sheets

• Earthquakes

How did the stickleback fish adapt to the absence of large predators in Bearpaw Lake?

• Grew thicker scales

• Developed larger fins

• Lost their pelvic spines

• Became more colorful

What is the role of the pitx1 gene in stickleback fish?

• Determines skin color

• Affects swimming speed

• Regulates spine development

• Controls body size

What did scientists discover about the pitx1 gene in freshwater sticklebacks?

• It was absent in freshwater fish

• Its regulatory switch was mutated

• It was completely inactive

• It had a different protein sequence

How did researchers confirm the role of the pitx1 switch in spine development?

• Through fossil analysis

• By observing fish behavior

• By measuring fish size

• Using reporter genes

What was the result of reintroducing the functional pitx1 switch into freshwater sticklebacks?

• Fish became more aggressive

• Fish regained pelvic spines

• Fish changed color

• Fish developed larger eyes

What does the repeated loss of pelvic spines in different stickleback populations suggest?

• Random genetic drift

• Consistent selective pressures

• Unrelated evolutionary paths

• Unique environmental conditions

What is a key mechanism driving the diversity of animal bodies according to the study?

• Climate variations

• Predator-prey dynamics

• Mutations in regulatory switches

• Changes in diet

How did the fossil record contribute to understanding stickleback evolution?

• By documenting spine loss over time

• By indicating migration patterns

• By revealing size variations

• By showing color changes

What does the study of sticklebacks reveal about evolutionary processes?

• They are unique to each species

• They can repeat under similar conditions

• They are unpredictable

• They are driven by random mutations