Quick Quiz
It looks like your students have some questions about Mechanisms of evolution. Reflect on what you have just learned and see how well you can respond. Just click on their raised hands!
You could respond:
“One reason is that sex introduces genetic variation between individuals, and
selection acts upon variation. This gives a population the flexibility to survive environmental change.”
You could respond:
“No, evolution can occur due to genetic drift. This means
that just by chance, especially in small populations, evolution can occur without specific selective pressure.”
You could respond:
“Variation, differential reproduction, and heredity.”
You could respond:
“Right, we often see cases of co-evolution when different
species have close ecological interactions with one another. The shape of the hummingbird’s bill and long tubular flowers
is a classic example. The form of the bird’s bill was influenced by the shape of the flower, which in turn affected the
evolution of the plant, which affected the evolution of the bird...and so on.”
You could respond:
“No, not really. During some stages of development many living
things look much like the same developmental stages their relatives pass through, but they do not recapitulate adult ancestors.
For example, mammals evolved from ancient fish and embryonic mammals share features with embryonic fish, but at no point do
they closely resemble adult fish.”
You could respond:
“Certainly. Mutation, migration, genetic drift, and natural selection.”
You could respond:
“This shows us that a seemingly small genetic change can cause big differences in how a living thing is built.”
You could respond:
“Yes, and you still do. You are sitting on it and it’s called your coccyx. Having a tail is part of your evolutionary history.”
