1 A 4 Evidence of Evolution Biological evolution

1. A. 4 Evidence of Evolution Biological evolution is supported by scientific evidence from many disciplines, including mathematics.

Scientific evidence of biological evolution uses information from geographical, geological, physical, chemical and mathematical applications.

Molecular, morphological and genetic information of existing and extinct organisms add to our understanding of evolution.

Fossils show change over time.

How rocks and fossils are dated

Relative dating: dating a fossil relative to other fossils, without knowing its actual age. • Strata at one location correlated to strata at another location

Dating fossils using the relationships within phylogenetic trees

Absolute dating: Determining a Fossil’s Age in Years • Radiometric Dating • Mathematical Calculations

Radiometric dating – dating using decay of radioactive isotopes • Radioisotopes have a half-life: the number of years it takes for 50% of the original sample to decay. • Incredibly reliable method for dating; only 1% error rate!

How Radiometric Dating Works:

Carbon-14 is a very important radioisotope • An organism accumulates some carbon-14 in its body when it is alive • When the organism dies, the carbon-14 will start decaying to become nitrogen-14

C-14 is used to date fossils up to 75, 000 years old • For older fossils, radioisotopes with longer half-lives are necessary • Can also date the rocks that fossils are found in

Mathematical calculations can take into account information from chemical properties and/or geographical data. Graph of Uptake of Trace Elements by Diffusion of a Fossil

Magnetic reversals can be used to date rocks when other methods fail. ― Occur when the earth’s north and south magnetic poles reverse.

Morphological homologies represent features shared by common ancestry.

Homologous Structures: arisen from common ancestor. • Same structure, but different function

Analogous Structures: no recent common ancestor; due to convergent evolution. • Same function, but different structure What do all of these organisms have in common?

Vestigial structures are remnants of functional structures, which can be compared to fossils and provide evidence for evolution.

Vestigial Structures in Humans: • Tailbone • Wisdom teeth • Vomeronasal organ (secondary sense of smell found in some animals) • Ear-orienting muscles • Goosebumps • Supernumerary nipples in some humans

Biochemical and genetic similarities, in particular DNA nucleotide and protein sequences, provide evidence for evolution and ancestry.

Example: Analysis of sequence data sets

Phylogenetic tree constructed using nucleotide substitutions per 1 kilobase of genomic sequence.

The universal genetic code: implies that all life on earth ultimately descends from a common ancestor.

Mathematical models and simulations can also be used to illustrate and support evolutionary concepts.

Example: Graphical analyses of allele frequencies in a population

Biogeography: geographic distribution of species • Closely related species are usually found in the same geographic region

Comparative embryology: embryos of vertebrates share many anatomical homologies

Learning Objectives: LO 1. 9 The student is able to evaluate evidence provided by data from many scientific disciplines that support biological evolution. [See SP 5. 3] LO 1. 10 The student is able to refine evidence based on data from many scientific disciplines that support biological evolution. [See SP 5. 2] LO 1. 11 The student is able to design a plan to answer scientific questions regarding how organisms have changed over time using morphology, biochemistry and geology. [See SP 4. 2]

LO 1. 12 The student is able to connect scientific evidence from many scientific disciplines to support the modern concept of evolution. [See SP 7. 1] LO 1. 13 The student is able to construct and/or justify mathematical models, diagrams or simulations that represent processes of biological evolution. [See SP 1. 1, 2. 1]