Evidence for evolution

Question 1

Developing the theory of evolution

Answer 1

• Darwin and Wallace helped formulating the theory of evolution by natural selection.
• Darwin observed many different types of finch on the Galapagos Islands but he believed they must be related due to many similarities.
• He concluded a bird born w/ beak more suited to food available would be more likely to survive than one whose beak was less suited.
• Those that survive pass their trait to offspring and over time all finches in the area share the shape of beak.
• This was called natural selection.

Question 2

Palaeontology

Answer 2

• Palaeontology is the study of fossils and the fossil record.
• Fossils are formed when animal and plant remains are preserved in rocks.
• Over time sediment form layers of rock; different layers show diff. eras and most recent is at top.
• So fossils can be arranged in chronological order and gradual changes in organism can be observed and provide evidence.
• Fossil record is not complete as soft bodied organisms decompose quickly before they can fossilise. Conditions needed for fossils are not often present. Fossils can be destroyed by earth movements like volcanoes or still be undiscovered.

Question 3

Comparative anatomy

Answer 3

Comparative anatomy is the study of similarities and differences in the anatomy of different living species by looking at homologous structures.

Question 4

Homologous structures

Answer 4

• Homologous structure is a structure that appears superficially different in different organisms, but has the same underlying structure.
• Presence of homologous structures gives evidence for divergent evolution: this describes how, from a common ancestor, different species have evolved, each with a different set of adaptive features.
• Type of evolution will occur when closely related species diversify to adapt to new habitats as a result of migration/loss of habitat.

Question 5

DNA evidence

Answer 5

• Theory of evolution suggests that all organisms have evolved from shared common ancestors.
• Evolution is caused by gradual changes in the base sequence of organisms’ DNA.
• So organisms that diverged away from each other more recently should have more similar DNA.

Question 6

Molecular evidence

Answer 6

• Sequence of amino acids in proteins and antibodies can be compared.
• Organisms that diverged away from each other more recently have more similar molecules.
• As less time has passed for changes in molecules to happen.