Evidence of Evolution

• Evolution is a continuous process of gradual modifications or changes in organisms.

• Patterns of evolution can be detected by viewing species in relation to one another.

• Evidence of evolution can be found through different fields of science.

Fossil Evidence

Bones, Molds, Casts, Amber

Fossil Record

• Fossils in the lower layers were present on earth before fossils in the upper layers.

• Law of superposition.• Descent with

modification (Darwin’s first law of evolution).

• Fossils show similarities and differences.

Biogeography

• Involves the mapping and study of the patterns of distribution of fossils and living organisms within and between the world's regions.

Embryological Development

• Compares the similarities of developing vertebrate embryos indicating common ancestry.

Homologous and Analogous Structures

•Modified structure that is seen among different groups of descendents–Provide strong evolutionary

relationships–Shows that several different species

have one common ancestor–Also known as comparative

anatomy

Comparative Anatomy

•Wings are analogous, though bones are homologous

Homologous Structures• Differences – appearance and function• Similarities – skeletal structure, derived from

same embryological development

•Forelimbs of the following organisms are homologous because they have the same internal skeletal structure even though they look different externally and have different functions.

Analogous Structures

• Butterfly wings and bird wings are analogous because they have the same function and appearance even though they have a different internal structure and develop differently.

•Similarities – function and appearance•Differences – embryological development and internal structure

Vestigial Structures (useless feature)

• Body structure that is greatly reduced in function that may have been useful to an ancestor.– Ex: human appendix, whale femur, coccyx

ear muscles, wisdom teeth

Biochemistry (Similarities in Macromolecules)

• Scientists can compare DNA sequences, amino acids sequences or proteins to view similarities and differences among organisms.

•The amino acid sequence in human hemoglobin and gorilla hemoglobin differ by one amino acid, while human and frog hemoglobin differs by 67 amino acids.

Mechanisms/Patterns of Evolution

Mechanisms/Patterns of Evolution

• Divergent Evolution-occurs when isolated populations of a species evolve

independently– Ex: Different food available in different

habitats (Galapagos Finches)-Eventually, separated populations will become so

different they can no longer interbreed (results in new species)

Mechanisms/Patterns of Evolution

• Convergent Evolution-When different species with different ancestors develop similar characteristics-Environment selects similar phenotypes-Ex: Sharks and porpoises (fish vs. mammal) develop streamlined bodies and fins (analogous structures)

Mechanisms/Patterns of Evolution• Coevolution - two or more species evolve

in response to each other– Flowers & pollinators