learning objectives 1 Flashcards
What is a lineage?
The evolutionary history of a certain species, often illustrated through an evolutionary tree.
What is a “trait”?
A measurable characteristic of an organism, which can be physical or behavioral.
What is convergent evolution?
Convergent evolution is when a trait is shared between two species because it evolved independently in both lineages.
Give an example of convergent evolution.
Wings in macaws and dragonflies, which evolved independently in both species.
What is a homologous trait?
A trait shared between two species because they inherited it from a common ancestor.
Give an example of a homologous trait.
The backbone in trout and macaws or wings in macaws and hummingbirds.
Explain “descent with modification and divergence.”
It’s the pattern of evolution where species change over time, becoming more distinct from one another and their common ancestor, often leading to the formation of new species.
What are the three evolutionary processes?
Mutation, genetic drift (both random), and natural selection (not random).
What happens to a population with infinite resources?
It undergoes exponential growth, with population size increasing rapidly without limiting factors.
What are possible long-term outcomes for a rabbit population?
The population could shrink to zero, cycle up and down, or level off.
What factors could limit the growth of a species’ population?
Predation, starvation, emigration, habitat loss, pathogens, natural disasters, insufficient habitat, and pollutants.
Why do populations evolve but individuals do not?
Evolution acts on populations over time as individuals with certain traits survive and reproduce, but it doesn’t change individuals during their lifetimes.
What are the three properties of a trait required for evolution by natural selection?
Variation, heritability, and an impact on survival or reproduction.
Why must a trait be heritable for natural selection to cause evolution?
Heritability ensures that offspring resemble their parents, allowing advantageous traits to spread through a population.
How can there be natural selection without evolution?
If the selected trait is not heritable, natural selection occurs, but it doesn’t lead to evolutionary change in the population.
