U8 Concept 3: Evidence for Evolution

​Concept 3: Evidence for Evolution

Overview

• Evolution is considered to be the “unifying theme

of biology” because it ties together evidence and
research from many branches, including:
– Paleontology: study of prehistoric life through the

fossil record.

– Morphology: study of the form of living things.
– Biogeography: study of the geographic distribution

of plants and animals.

• Looks at where living things are located.

– Embryology: study of embryo development.
– Biochemistry: study of chemical processes in living

things.

• Evidence has also come from Direct Observation.

Evidence in Paleontology

• Fossils = preserved remains of organisms

(bones, footprints, feces, etc.)
– The fossil record reveals a history of the types of

organisms that have lived on Earth (including now
extinct species) and the ages of those fossils.

– Transitional fossils = link

ancestral species to their
descendants.

• Critical for piecing together

evolutionary history.

• Ex. Archaeopteryx, the transitional

fossil between birds and dinosaurs

Evidence in Morphology

• Homologous structures = similar structures

that suggest evidence of common ancestry.
– Similar structure, but different function, due to being

used in different environments.

– Result of divergent evolution.

Multiple Choice

14. The similarity of these structures is one form of evidence that the organisms ________.

• a. share a common ancestor

• b. all grow at different rates

• c. evolved instantaneously

• d. do not share a common ancestor

Evidence in Morphology

• Vestigial structures= structures with little or no

function to an organism.
– Could be leftover from an ancestor that had used the

structure, and thus could provide evidence of
divergent evolution.

Multiple Choice

15. Anatomical structures that appear to be derived from a functional structure in an ancestor, but that currently do not serve an important function, are called ________ structures.

• a. homologous

• b. analogous

• c. vestigial

• d. fossilized

Evidence in Morphology

• Analogous structures= similar structures that

evolved independently in different organisms due
to serving similar purposes.
– Different structurally but same functionally, due to

living in similar environments.

– Result of convergent evolution, therefore are not

related.

Multiple Choice

16. The phylogenetic tree illustrates the relationship between humans and our closest living relatives. The tree was based on biochemical comparisons, including DNA and amino acid sequences. What statement COULD we make about the four species based on the phylogenetic tree?

• a. The orangutan has nothing in common with the other three organisms.

• b. The four have molecular similarities, but have their own unique traits.

• c. The is no evidence of any connection between the four organisms.

• d. Humans are in no way similar to the other three organisms.

Evidence in Biogeography

• The distribution of organisms lines up with what has

been discovered about continental drift and Pangea.
– Species in nearby geographic areas often resemble

each other, with variation for their specific
environments.

• Ex. Island species are more closely related to mainland

species than they are to species on similar islands on the
other side of the world.

– Potential evidence of

divergent evolution.

– Endemic species =

species that exist only
in one geographic
region.

• Ex. Galapagos tortoises

Evidence in Embryology

• Similarities in the

embryos of vertebrates
early in development
suggests common
ancestry among
vertebrates.

​This site is AWESOME at showing how indistinguishable embryos can be!  https://www.pbs.org/wgbh/nova/evolution/guess-embryo.html

Evidence in Biochemistry

• Analyzing DNA and proteins

from different species allows
us to compare similarities to
predict common ancestry.
– Closely related species would

have similar DNA sequences.

• Pseudogenes also provide

evidence of divergent
evolution.
– Nonfunctional genes

• Think of them as the vestigial

structures of your DNA.

Ex. Hippopotamus vs.

Humpback whale

Multiple Choice

17. The fact that many of the proteins produced by humans have identical or nearly identical counterparts in chimpanzees suggests that...

• a. all proteins are basically the same.

• b. humans and chimps actually belong to the same species.

• c. humans and chimps share a common ancestor.

• d. humans and chimps have convergently evolved.

Evidence from

Direct Observation

• Microevolution that has been directly observed due

to occurring in populations with short life cycles that
reproduce quickly.
– Examples:

• Peppered moths
• Mosquitos resistant to pesticides like DDT
• MRSA = a type of antibiotic-resistant bacteria

Multiple Choice

21. While the shark and dolphin are similar in appearance, dolphins evolved from ancestors that were very different from sharks. The current similarity between sharks and dolphins is an example of _________.

• a. coevolution

• b. biogeography

• c. convergent evolution

• d. divergent evolution

Multiple Choice

What type of selection is pictured here?

• Directional

• Disruptive

• Stabilizing

Multiple Choice

What type of selection is pictured here?

• Directional

• Disruptive

• Stabilizing

Multiple Choice

A particular bird species lays an average of 4 eggs per nesting season. If more than four eggs are produced, the parents may not be able to feed the hatchlings. If less than 4 eggs are produced, there is an increased risk that predators will take all the young that have been produced.

• Directional

• Disruptive

• Stabilizing

Multiple Choice

A lizard population lives in a very rocky area consisting of black rocks and white rocks. Black lizards can hide from predators by living on black rocks, and white lizards can hide from predators by living on white rocks. The intermediate grey colored lizard is found in fewer numbers because of its inability to hide from predators in this environment.

• Directional

• Disruptive

• Stabilizing

Multiple Choice

During the ice ages, the black bears of Europe increased in size.

• Directional

• Disruptive

• Stabilizing