"nothing in biology makes sense except in the light of evolution” ~Theodosius Dobzhansky (1900-1975)

What is a Theory? It is a well-supported, testable explanation of phenomenon observed in the natural world Can be used to make predictions Are not absolute, can be changed as new evidence is found

Geologic Time Scale The timeline of life on Earth Represents evolutionary time Divided into eons, eras & periods Each represents a major event First appearance Height of diversity Extinction Precambrian (oldest) Cenozoic (modern time) It shows us that life has changed over time

What is evolution? Let’s watch: Stated Clearly - What is Evolution

Several people tried to explain how or more so WHY organisms have changed over time. Jean-Baptiste Lamarck – Acquired traits (Use it or Lose it) were passed down by ancestors Charles Darwin – Evolution occurred through Natural Selection (Survival of the Fittest) Descent with Modification

Lamark's Theory of Acquired Characteristics Thought that you would gain or lose features if you overused or didn't use them Proven to be wrong! Photo courtesy of ucumari, creative commons, flickr

Charles Darwin developed the THEORY OF EVOLUTION BY NATURAL SELECTION  It explained how organisms changed over time  (ADAPTED)

Lamarck vs Darwin

Darwin was a British naturalist He traveled the world & made observations and sketches of many species His most famous travels were aboard the H.M.S. Beagle where he traveled to the Galapagos Islands These isolated islands are home to species that of plants and animals not found anywhere else in the world

Marine Iguana, photo courtesy of mtchm, flickr creative commons Blue-footed booby, photo courtesy of stirwise, flickr creative commons

Finch, photo courtesy of stirwise, flickr, creative commons Giant tortoise, photo courtesy of Planetgordon, flickr creative commons

Darwin noted that there existed many finches on the islands, but while they had similarities, each was adapted to eating a particular type of island food He concluded that the finches all came from one ancestral species and evolved into many new species Cactus finch, photo courtesy of zrim, flickr creative commons

Turtles? What about the turtles? Tortoises, actually (they live on land) Darwin noticed differences in the shell shape of tortoises on each island. Low vegetation – Dome-shape High & sparse vegetation – Saddle-back shape (allows for neck to stretch)

Darwin published this work to explain the variety of species that exist on the planet He proposed the “Theory of Evolution by Natural Selection”

A little info about Darwin The Father of Evolution Charles Darwin's Ideas

1. Variation exists among individuals in a species. 2 1. Variation exists among individuals in a species. 2. Individuals will compete for resources (food, mates, and space) 3. Competition would lead to the death of some individuals while others would survive 4. Individuals that had advantageous variations are more likely to survive and reproduce. This process came to be known as Natural Selection The favorable variations are called Adaptations Photo courtesy of digitalART2, flickr creative commons

Say in a species of blob… Say in a species of blob….there exists blobs of all shapes and sizes (variation) Blobs eat the little purple organisms that live underground and on the surface.

During a particularly hot year, food became less abundant (competition), blobs that had the ability to dig into the soil to get food had a better chance of survival. Many blobs died that year…….

The ones that survived mated and passed their genes to the next generation. (reproduction)

The next generation had move blobs with the pointed noses The next generation had move blobs with the pointed noses. That is NATURAL SELECTION. Variation Competition Survival Reproduction

What is Natural Selection? Natural Selection vs Artificial Selection What is Natural Selection

Fossil Evidence Shows numbers extinct animals Shows similarities between extinct animals and animals that are alive today The earth’s layers show a time scale of species and when they appeared on earth (and when they died out)

Dinosaurs have always fascinated us, movies such as Jurassic Park capitalize on that fascination. How do we know what dinosaurs looked like? We create a picture based on the bones we find (fossils) and use modern reptiles to guess at their texture and skin color.

Homologous structures – these are parts of the body that are similar, but have different functions ex. The flippers of whales, and the wings of birds All forelimbs of vertebrates have the same pattern of bones • Common ancestry

Ex. Bat & Butterfly wings Analogous Structures – these are body parts that evolved for similar function, but not from a common ancestor Ex. Bat & Butterfly wings Both for flight Not related

Vestigial Organs – these are organs or parts that seem to have no function Whales have pelvic bones that do not attach to legs

Biochemistry and DNA When comparing the DNA of one species to another, more similarities are found in species that are more closely related. Lion photo credit: ucumari Tiger photo credit: digitalART2

Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks

Direct observation of species change Bacteria become resistant to antibiotics Wolves were bred over many generations to become dogs (artificial selection) • and then bred further to create a variety of breeds very different from ancestor

What is a species anyway? Organisms that can interbreed with on another, and produce fertile offspring

If 2 organisms are closely related enough & they CAN mate, the offspring is called a HYBRID & is sterile!! Example:  ligers and mules

Evidence Evidence for Evolution Evolution Evidence