Evidence for Evolution

Scientific evidence of biological evolution uses information from

geographical, geological, physical, chemical and mathematical

applications.

1.A.4

Evidence of Biological Evolution

• Geographic – Distribution of living things on Earth

• Geological – Examples include fossils

• Physical – Comparative Morphology/Embryology

• Chemical – Comparison of DNA nucleotide and protein sequences

• Mathematical – Radiometric Dating of Fossils or Molecular Clocks

Phylogenetics

• Evidence is then used to determine evolutionary relationships between organisms and the evolutionary history of an organism (this is called phylogeny)

• Relationships and history are depicted in diagrams known as phylogenetic trees

Tree of Life Web Project

Phylogenetic Tree

Geographic Evidence

Geographic Evidence

• Distribution of living things around the globe provides information about the past history of living things and the surface of the Earth (biogeography)

• Use biogeography to understand the evolution of a species

Evolution of the Camel Family

Madagascar’s Endemic Species

• Click on the hyperlink above to read about the endemic species of Madagascar

Geological Evidence

Geological Evidence

• Examples include fossils and iron oxides in rock

• Earth core samples show environmental change over time

Geological Evidence (Fossils)

• Fossils can be dated by a variety of methods that provide evidence for evolution

• Provide a record of early life and evolutionary history

• Physical evidence of an organism that lived long ago

Fossil Dating

• Law of superposition – “relative” age of fossils

Fossil Dating

• Determine the age of a fossil by finding the age of the rock where the fossil is found

(513-512 mya)

Fossil Dating • Determine the absolute age of a fossil by

looking at the rate of decay of isotopes (radiometric dating)

• Carbon-14: half life of 5730 years

• Uranium-238: half life of 4.56 billion years

Carbon Dating

Physical Evidence

Physical Evidence

Physical evidence of evolution includes:

• Comparative Anatomy

1. Morphological Homologies

2. Vestigial Structures

3. Analogous Structures

• Comparative Embryology

Homologous Structures

• Homologous structures are structural features that originated in a common ancestor

• Similar in structure but may differ in function

Vestigial Structures

• Vestigial structures are remnants of functional structures that were once useful in the ancestor of the modern day organism

Analogous Structures (Homoplasies)

• Structures that shares a common function, but are not similar in structure

• Demonstrates that species evolved independently of one another, not related

• Result from convergent evolution

Comparative Embryology

• Comparison of embryos and embryo development

• Evidence of common ancestry

Chemical Evidence

Chemical Evidence

• Biochemical and genetic similarities: DNA nucleotide and protein sequences

• Show evidence for evolution and ancestry

• Analyze notable genetic similarities or differences

• All domains of life rely on the same genetic code (this is evidence of common ancestry for ALL life)

DNA Sequence Alignment

Species of Beetles

Universal Genetic Code

Mathematical Evidence

Mathematical Evidence

• Molecular clocks use mutations to estimate evolutionary time (assume that genetic mutations occur at a constant rate)

• Estimate divergence

Molecular and genetic evidence from extant and extinct organisms

indicates that all organisms on Earth share a common ancestral

origin of life. 1.D.2

Evidence for Relatedness of All Life

• Structural and functional evidence supports the relatedness of all domains (Eukarya, Bacteria, Archaea

Structural and Functional Evidence • DNA and RNA are carriers of genetic

information

• Genetic code is shared by all modern living systems

• Conservation of metabolic pathways

Conservation of Metabolic Pathways

• Glycolysis is the MOST widespread metabolic pathway among Earth’s organisms

• Suggests glycolysis evolved very early in life

Structural Evidence Supports the Relatedness of All Eukaryotes

• Cytoskeleton

• Membrane-bound organelles

• Linear chromosomes

• Endomembrane system (ER, Golgi, Nuclear envelope)

HOX Genes

• Body plan genes in animals (common ancestry)

Populations of organisms continue to evolve.

1.C.3

How do we know that evolution has occurred in all species?

• Geological record of Earth’s history through the study of fossils

• If the Earth has changed over time, then the organisms which inhabit the Earth must have the ability to evolve or they will die

Evolution Continues to Occur

• Mutations that cause chemical resistance:

- resistance to antibiotics (super cool video)

- resistance to pesticides and herbicides

- resistance to chemotherapy drugs

Pesticide Resistance

Emergent Diseases

• Mutations of existing viruses

• Spread of existing viruses from other animals