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 Finches

The finches beaks were different based on the type of food they ate.

Actual photos of the finches

Niches of Darwin’s Finches

Keep in mind……

• Populations or species evolve, not individuals

Major pieces of Evidence for Evolution1. Fossils2. Comparative Anatomy (homologous structures)3. Selective Breeding of Animals and Plants

1. Fossil EvidenceFossils: 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-ancestral descent and lineages can be generated

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

Evolution Evidence: 2. Comparative AnatomyTypes of Structures:• A. Homologous

structures (same structure, diff. use)

• Shows possible descent from a common ancestor

Homologous Structures

6. Selective Breeding• We have bred various animals and plants

for specific purposes, selecting the traits WE want them to acquire.

• The process in which humans select which plants or animals to reproduce based on certain desired traits is called selective breeding.

• Ex- horses, dogs, strawberries, corn• This is controlled evolution.

Darwin’s Theory1. Variation- There is a natural variation in any

population. Every individual has its own combination of traits.

2. Overproduction- more offspring are born than survive.

3. Struggle to Survive- members of a species compete for food, habitat, etc. (limits population)4. Reproduction- individuals that are best adapted to their environment are likely to have many offspring that survive.

Natural selection- “survival of the fittest”- The species most fit for their environment will survive to pass on their traits.

Darwin’s Theory of Natural Selection

What Is Natural Selection? Darwin proposed the theory that evolution happens through a process that he called natural selection. Individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals.

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

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!

Final words…...

• “Absence of evidence is not evidence of absence.”