Evidence of Evolution Topic 7.6 Evolution is supported by - - PowerPoint PPT Presentation

Evidence of Evolution

Topic 7.6

Evolution is supported by scientific evidence from many disciplines (geographical, geological, physical, biochemical, and mathematical data). EVO – 1.M.1, 1.N.1, 1.N.2

Scientific Evidence of Evolution

• Geographical – Distribution of living things on

Earth

• Geological – Examples include fossils
• Physical – Comparative Morphology/Embryology
• Biochemical – Comparison of DNA nucleotide

and protein sequences

• Mathematical – Radiometric Dating of Fossils or

Molecular Clocks

Phylogeny

• Scientific evidence is used to determine

evolutionary relationships between organisms and the evolutionary history of an organism (phylogeny)

• Relationships and history are depicted in

diagrams known as phylogenetic trees or cladograms

Tree of Life Web Project

(Click on this link explore the collaborative effort to discover the phylogeny of every species on Earth)

Phylogenetic Tree

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)

• Scientists can used biogeography to

understand the evolution of a species

Evolution of the Camel Family

Madagascar’s Endemic Species

(Click on this link to read about Madagascar’s endemic species)

• Geographic isolation may lead to the

evolution of endemic species

• Endemic species exist in only one geographic

region and are found nowhere else in the world, usually located in biodiversity hotspots

Geological Evidence

• Examples include fossils and iron oxides in

rock

• Earth core samples show environmental

change over time

Fossils

• Fossils provide a record of early life and

evolutionary history

• Fossils provide physical evidence of an
• rganism that lived long ago

Fossil Dating

• Fossils can be dated by a variety of methods,

including:

– Determining the age of the rocks where a fossil is found – Using the rate of decay of isotopes including carbon-14 – Geographical data

Fossil Dating

• Determine the age
• f a fossil by finding

the age of the rock where the fossil is found (513-512 mya)

Relative Dating

• Determines the relative order of past events
• Law of Superposition – a vertical set of strata

(layers of rock) is a chronological record of the geological history of that strata

• Youngest layers are on top and the oldest are
• n the bottom

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 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

Homologous Structures

• Morphological homologies represent features

shared by common ancestry

Vestigial Structures

• Vestigial structures are remnants of functional

structures that were once useful in the ancestor of the modern day organism

• Evidence of common ancestry

Analogous Structures

(This 2 minute video explains the difference between homologous and analogous)

• Also known as homoplasies
• Structures that shares a common function, but

are not similar in structure

• Demonstrates that species evolved

independently of one another - not from a common ancestor

• Result from convergent evolution

Comparative Embryology

• Comparison of embryos and embryonic

development

• Evidence of common ancestry

Biochemical Evidence

• A comparison of DNA nucleotide sequences

and/or protein amino acid sequences provides evidence of evolution and common ancestry

• Scientists analyze notable genetic similarities

and differences

Sequence Alignment

• DNA, RNA, and amino acid sequences can be

aligned with software to examine similarities and differences between species

Biochemical Evidence

• Genetic code is universal

– All organisms use the same genetic code to operate their cell(s) – Believed to be established early in the history of life – Evidence of common ancestry of all life forms

• Some biochemical pathways are universal

– Similar processes for photosynthesis and respiration between organisms

Universal Genetic Code

Mathematical Evidence

(This 2 minute video explains the molecular clock)

• Molecular clocks use mutations to estimate

evolutionary time and divergence from a common ancestor

• Assume that genetic mutations occur at a

relatively constant rate

Many fundamental molecular and cellular features and processes are conserved across all organisms.

EVO – 2.B.2

Molecular and Cellular 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

• The metabolic pathway glycolysis is evidence

for the relatedness of all domains of life (Eukarya, Bacteria, Archaea)

• Glycolysis is the MOST widespread metabolic

pathway among Earth’s organisms

• Suggests glycolysis evolved very early in the

history of life

Common Ancestry

Topic 7.7

Structural evidence indicates common ancestry of all eukaryotes.

EVO – 2.B.2

Structural Evidence Supports the Relatedness of All Eukaryotes

• All eukaryotic organisms share common

structures such as:

– Membrane-bound organelles – Linear chromosomes – Genes that contain introns

Linear Chromosomes

• All eukaryotes are composed of cells with

linear chromosomes

• Prokaryotes contain a single, circular

chromosome

Genes and Introns

• Eukaryotic genes contain non-coding regions

called introns which are removed during RNA processing

• Prokaryotic genes DO NOT contain introns

Continuing Evolution

Topic 7.8

All species have evolved and populations continue to evolve.

EVO – 3.A.1, 3.A.2

Continuous Change in the Fossil Record

• The fossil record provides physical evidence of

change over time and continuous change

Evolution Continues to Occur

• Evolution of resistance to
• antibiotics
• pesticides and herbicides
• chemotherapy drugs

Pesticide Resistance

Emergent Diseases

• Pathogens (viruses, bacteria, fungi, protozoa,

worms) evolve and cause emergent diseases

• Emergent diseases are infections that have

recently appeared within a population or those whose incidence or geographic range is rapidly increasing