5.1 Evidence for evolution

Question 1

What is evolution?

Answer 1

Evolution occurs when heritable characteristics of a species change over time. These heritable characteristics are in the form of alleles on the chromosomes, which contain genotypes expressed outwardly as phenotypes

Question 2

How does the fossil record provide evidence for evolution?

Answer 2

The fossil record provides evidence of physical and sometimes behavioral changes in species over time, including transitional fossils which display characteristics between ancestral groups and indicate macroevolution. Examples include the Archaeopteryx, showing the transition from prehistoric reptiles to birds

Question 3

How does selective breeding of domesticated animals show that artificial selection can cause evolution?

Answer 3

Selective breeding (artificial selection) demonstrates evolution through human intervention by selecting organisms with desired traits for breeding, leading to significant changes from their ‘wild’ ancestors. Examples include the variety of dog breeds from their wolf ancestors​

Question 4

What are homologous structures?

Answer 4

Homologous structures are similar in position, structure, and evolutionary origin but not necessarily in function, indicating a common ancestor. They show that even if species diverge over time, there can be underlying similarities that point back to a shared lineage.

Question 5

How do homologous structures provide evidence for adaptive radiation?

Answer 5

The pentadactyl limb is a prime example of how homologous structures provide evidence for adaptive radiation, showcasing divergent evolution. Despite different species having limbs that appear different and serve various functions, the fundamental structure shared among them (the pentadactyl limb) points to a common ancestor, demonstrating how species have adapted to their unique environments over time.

Question 6

Compare the pentadactyl limb of mammals, birds, amphibians, and reptiles.

Answer 6

The pentadactyl limb, a limb with five digits, is found in mammals, birds, amphibians, and reptiles, indicating a common ancestral origin. Despite the limb’s similar structure across these groups, it has adapted to different methods of locomotion in each group due to divergent evolution​

Question 7

How can populations of a species gradually diverge into separate species by evolution?

Answer 7

Populations of a species can diverge into separate species through speciation, where genetic differences accumulate to the point they can no longer interbreed. This process can be driven by environmental changes, geographical isolation, and continuous variation within populations

Question 8

How does continuous variation across the geographical range of related populations match the concept of gradual divergence?

Answer 8

Continuous variation across geographical ranges, such as the beak sizes of Galapagos finches, supports gradual divergence by showing how related species adapt to their environments over time, potentially leading to new species. This variation is influenced by environmental factors and showcases microevolution in action

Question 9

Explain the development of melanistic insects in polluted areas.

Answer 9

Industrial melanism, such as in the peppered moth (Biston betularia), shows how environmental changes (e.g., pollution from industrialization) can lead to evolutionary adaptations. Darker moths became more prevalent in polluted areas due to better camouflage, demonstrating natural selection and a shift in allele frequencies towards those favoring melanism​