Evolution Descent with Modification: A Darwinian View of Life

Evolution Defined Evolution: gradual hereditary changes in groups of living organisms over time. November 24, 1859

Lamarck’s Theory Jean Baptiste de Lamarck, 1809 First theory of evolution- how species change

Lamarck’s Theory **Inheritance of acquired characteristics- The changes acquired during an animals lifetime from use and disuse may be passed on to its offspring. Law of use and disuse- parts used by animal become stronger, parts used less become weaker

Darwin vs. Lamarck

Charles Darwin Father of Evolution Developed the theory of evolution after his trip on the H.M.S Beagle Published the Origin of Species on November 24,1859

Darwin’s Voyage

Galapagos Islands Noted subtle differences in finches & tortoises, by island & compared to mainland

Actual photos of the finches

Niches of Darwin’s Finches

Darwin’s Theory Variation- There is a natural variation in any population. Overproduction- more offspring are born than survive. Competition- members of a species compete for food, habitat, etc. (limits population) Adaptations- any inherited trait that improves survival. Natural selection- “survival of the fittest”- The species most fit for their environment will survive to pass on their traits. Speciation- If enough changes take place, new species may be formed

Keep in mind…… Populations or species evolve, not individuals

Major pieces of Evidence for Evolution Fossils Comparative Anatomy (homologous structures, vestigial structures, analogous structures) Comparative Embryology Biochemical Evidence Biogeography Selective Breeding of Animals and Plants Post Darwin: 7. Molecular Genetics: DNA/Amino acid Sequencing 8. Chromosomal Changes (Mutations)

1. Fossil Evidence Fossils: remains and traces left behind by organisms -most direct evidence for evolution -provides a record of ancient organisms that have existed -able to generate a timeline -observe the presence of vestigial structures -ancestral descent and lineages can be generated -more aquatic fossils vs. terrestrial have been found Types of Fossils: imprints, hair, nails, tissue, and other remains Locations: sedimentary rock, ice, amber, tar, quicksand, petrification

Evidence: 1. The Fossil Record Shows succession of forms over time Transitional links Vertebrate descent

Ex- Evolution of the Horse Horse Evolution: The fossil record shows: Size: Smaller to larger Toes: 3 toes on back foot/4 on front 1 toe bigger/2 toes reduced = HOOF! Molars: Eating leaves to grazing = bigger teeth

Dating Fossils Location within the rock strata (use index fossil) Radioactive isotopes (half-life) K40 half life is 1.3 billion years argon U235 half life is 704 million years → lead U238 half life is 4.5 billion → lead C14 half life is 5730 years  nitrogen

Evolution Evidence: 2. Comparative Anatomy Homologous Structures 3 Types of Structures: A. Homologous structures (same structure, diff. use) Shows possible descent from a common ancestor B. Vestigial structures (no apparent use today) Ex: whale/snake hindlimbs; wings on flightless birds

Extinct Whale w/ small hind limbs- Vestigial Structure

Analogous Structures C. Analogous Structures- Same function, but different structure. -see examples here. Show Convergent Evolution due to similar niches.

Evolution Evidence: . 3. Comparative Embryology Vertebrate embryos- look very similar during early development. Pharyngeal pouches (gills), ‘tails’ as embryos Indicates common ancestors.

Evolution Evidence: 4. Comparative Biochemistry Biochemistry is used to support evidence about evolutionary relationships Similar molecules in different species determine how much difference there is between the species. More differences = longer time span since common ancestor Less differences = shorter time span since common ancestor

Evidence: Molecular Biology Mutations in a genome occur at a predictable rate. Therefore, base pair sequences in two populations can be compared, in particular amino acid sequences, and by looking at the number of mutagenic differences between the two, and inference can be made as to how long ago the two populations diverged reproductively. ATTGCCAAGCCT ATTGCGAAGCCT

Evolution evidence: 5. Biogeography Geographical distribution of species Examples: Islands vs. Mainland Australia Continents

Specific molecules can indicate phylogeny! Phylogeny: is the line of evolutionary descent

Common Ancestory- Phylogenic Tree

Phylogenic Tree with humans

Molecular evidence for common Ancestry

6. Selective Breeding For millenia, we have bred various animals and plants for specific purposes, selecting the traits WE want them to acquire. Ex- horses, dogs, strawberries, corn This is controlled evolution.

7. Examples of Natural Selection Peppered moth antibiotic resistance

Examples of Modern (Recent) Evolution Peppered Moth- during day sits on tree trunk. More active at night. Before 1850 tree trunks were light in color, and most moths were gray. After 1850 (industrial revolution), the predominant color of moth was black, which matched the soot on the trees. peppered moth activity

Percentage of Antibiotic Resistant Gonorrhea Strains 1980-1990

Key Points to Remember A population evolves not an individual organism The accumulation of small changes over long periods of time results in larger changes A new species emerges with slightly different characteristics usually because of being isolated. How and why organisms are able to transmit heritable traits to the next generation was not explained by Darwin. Common Ancestry!

Evidence for evolution!! includes Evidence of Evolution Physical remains of organisms Common ancestral species Similar genes which is composed of which indicates which implies The fossil record Geographic distribution of living species Homologous body structures Similarities in early development

Final words…... “Absence of evidence is not evidence of absence.”