understanding evolution
TRANSCRIPT
EVOLUT ION
Charles Robert Darwin
Charles Darwin was born in England on February
12, 1809
After graduating from the best school at Shrewsbury in 1825, Darwin went to the University of Edinburgh to study medicine.
In 1827 he dropped out of medical school and entered the University of Cambridge.
Charles Robert Darwin
Darwin was an avid collector of beetles while at Cambridge
Charles Robert Darwin
In 1831, he joined a 5 year scientific expedition on the survey
ship HMS Beagle as their geologist.
Charles Robert Darwin
The idea of evolution has been around for a long time (even before Darwin)
Charles Robert Darwin
Darwin read a book called “Principles of Geology” by Charles Lyell on the Beagle
Charles Robert Darwin
Lyell suggested that the fossils found in rocks were actually evidence of animals that had lived many thousands or millions of years ago.
Lyell's argument was reinforced in Darwin's own mind by the rich variety of animal life and the geological features he saw during his voyage.
Charles Robert Darwin
Darwin noticed that each island supported its own form of finch which were closely related but differed in important ways.
Charles Robert Darwin
Darwin found that the shapes of tortoise shells corresponded to different habitats.
Charles Robert Darwin
Charles Robert Darwin Another scholar of the time, Thomas Malthus, studied populations
and had a great impact on Darwin’s understanding of finches, other organisms, and his theory of evolution.
Malthus believed that given unlimited resources, a population would grow exponentially.
Under normal conditions, a natural population would be limited by food, water, habitat, etc. resulting in a balancing of population numbers.
Influenced by the ideas of Malthus, Darwin proposed a theory of evolution occurring by the process of natural selection.
Charles Robert Darwin
Survival of the fittest
The animals (or plants) best suited to their environment are more likely to survive and reproduce, passing on the characteristics which helped them survive to their offspring.
Gradually, the species changes over time.
Charles Robert Darwin
Darwin worked on his theory for 20 years.
After learning that another naturalist, Alfred Russel Wallace had developed similar ideas
the two made a joint announcement of their discovery in 1858.
Charles Robert Darwin
In 1859 Darwin published : ‘ The Origin of Species ‘ by Means of Natural Selection
Evolution Change over time
Occurs to species, not individual
Explains diversity on Earth today
Great variety of types of living things
Between species 10 – 100 million species on earth
How Evolution Works :
Explained by Charles Darwin and Alfred Russell Wallace Darwin wrote On the Origin of Species
How Evolution Works
1. Overpopulation • more individuals born than can survive
How Evolution Works
2. Competition • for limited resources some will survive
How Evolution Works
3. Variation • Differences among individuals a result of genetic mutation –
changes in DNA
How Evolution Works
4. Adaptation
some variation gives some individuals a slight
survival advantage these are favorable traits
traits or characteristics that help an organism survive in its ecosystem
three types:
How Evolution Works
1.Structural and Behavioral :
Physical structure that helps organism survive
How Evolution Works
2. Chemical
Chemical that helps organism survive
Octopus Skunk
How Evolution Works
3.Camouflage
Allows an organism to blend with its environment
Owl Frog
Charles Darwin predicted: Darwin's Comet Orchid
The Forces of Evolution
Genetic Drift
Genetic Recombination
Mutation
Gene Flow
Natural selection
The Forces of Evolution
Genetic Drift
A population bottleneck : is a sharp reduction in the size of a population due to environmental events such as: (earthquakes, floods, fires, disease, or droughts)
Genetic Drift
B Founder effect : is the loss of genetic variation that occurs when a new population is formed by a very small number of individuals from a larger population
It was first fully outlined by Ernst Mayr in 1942
Recombination Genetics
Mutation
Gene Flow
Natural Selection That results in the adaptation of an organism
to its environment
Determines the traits that allow organism to multiply and survive
Evolution often occurs as a result of this process
Evidences of Evolution
The Fossil Record
Comparative anatomy
Embryonic Development
Vestigial organs
Molecular biology
The Fossil Record
Comparative anatomy
Embryonic Development
Vestigial Organs
Wisdom Teeth Third Eyelid Darwin’s Point Coccyx Appendix Goose Bumps Jacobson’s Organ Junk DNA Extra Ear Muscles Plantaris muscle
Molecular biology
Universal Codon Code Pseudogenes Vitamin C Human Chromosome 2 Endogenous retroviruses (ERVs)
Universal Codon Code
Pseudogenes Vitamin C
Human Chromosome 2
Endogenous retroviruses (ERVs)
Types of Evolution
Divergent Evolution
• Organisms have a common ancestor
• Changes in environment cause them to adapt
• So they may look/ act differently, but they are still related!
Types of Evolution
Convergent Evolution • Organisms have similar features • However, they don’t have a common ancestor! • So they may look/ act the same, but they are not related!
Types of Evolution
Convergent Evolution • Organisms have similar features • However, they don’t have a common ancestor! • So they may look/ act the same, but they are not related!
Speciation
The most widely accepted definition: A species is a group of individuals capable of interbreeding to produce
fertile offspring
it has a problem : Hybrid Infertility
Horse X Donkey = Mule (Cannot Reproduce and produce Fertile offspring)
Speciation
So a better definition of a species might be: A group of individuals capable of interbreeding to
produce offspring that are fertile and these offspring, in turn, can produce offspring that are fertile.
The process by which new species develop from the
existing species is known as : Speciation.
Speciation
Speciation
Evolution
Microevolution: • genetic change in a population from one generation to the next
Macroevolution: • Processes through which new species arise
Microevolution
Moths : • At the beginning of the Industrial Revolution in England, coal burning
produced soot that covered the countryside in many areas
Microevolution
• What do you think happened?
Microevolution
White moths became easier to see, while the black moths became harder to see.
The black moths were more likely to survive and pass on the gene for dark color to their offspring
Over time, the black moths have become more common
Macroevolution
• Transitional Fossils : Prominent examples:
Archaeopteryx
Tiktaalik
Darwinius masillae
Ardipithecus ramidus
Australopithecus afarensis
Macroevolution
Archaeopteryx : Origin of birds
Temporal range: Late Jurassic, 150.8–148.5 Ma
Macroevolution
Tiktaalik roseae : Fish to Reptile
Temporal range: Late Devonian, 375 Ma
Macroevolution
Tiktaalik roseae
Macroevolution
Darwinius masillae : Origin of Primates
Temporal range: Middle Eocene, 47 Ma
Macroevolution
Australopithecus afarensis: Apes to humans 2.9_3.9 Ma
Human Family Tree
Human Family Tree
Human Family Tree
Human Family Tree
Human Family Tree
Thank you
Samer Hamid