Variations within a species are most likely the result of Aim: Darwin’s Natural Selection Enter Date Warm-up: Variations within a species are most likely the result of  (1.) mutations and sexual reproduction   (2.) mitosis and asexual reproduction   (3.) synapsis and disjunction  (4.) overpopulation and recombination HW: Regents Biology

Lamarck Was born in 1744 in Northern France Dedicated his life to studying how animals grow. He is the first to propose mechanisms explaining how organisms change over time. Regents Biology

Use and Disuse The theory that an organism could alter the size or shape of a particular organ by using their bodies in new ways. Example – by trying to use their feet for flying, birds could eventually grow a second set of wings. Example – if a bird did not use its wings, it would lose it. Regents Biology

Inheritance of Acquired Traits The theory that during if an animal acquires a trait during its lifetime, it can pass it to its offspring. Example – You dye your hair red, your children will be born with red hair. Regents Biology

Charles Darwin Proposed a way how evolution works How did creatures change over time? by natural selection Collected a lot of evidence to support his ideas What did Darwin say? What evidence supports Evolution by Natural Selection? What impact did Evolution have on biology? Regents Biology

Natural Selection The idea that individuals that are better suited for their environment will survive and reproduce most successfully. For example – a fish will survive better in the ocean than a human will.

Voyage of the HMS Beagle Invited to travel around the world 1831-1836 (22 years old!) makes many observations of nature main mission of the Beagle was to chart South American coastline After graduation Darwin was recommended to be the conversation companion to Captain Robert FitzRoy, preparing the survey ship Beagle for a voyage around the world. FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain. Darwin noted that the plants and animals of South America were very distinct from those of Europe Robert Fitzroy Regents Biology

Voyage of the HMS Beagle Stopped in Galapagos Islands 500 miles off coast of Ecuador The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled Darwin. On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland. It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified on the different islands Regents Biology

Galapagos Recently formed volcanic islands Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland Regents Biology 800 km west of Ecuador

Darwin found…many unique species Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands? Regents Biology

Darwin found…clues in the fossils present day Armadillos Darwin found…clues in the fossils Darwin found: Evidence that creatures have changed over time ancient Armadillo Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent? Regents Biology

Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like? Regents Biology

Darwin found… birds He thought he found very different kinds… Many different birds on the Galapagos Islands. He thought he found very different kinds… Regents Biology

But Darwin found… a lot of finches Darwin was amazed to find out: All 14 species of birds were finches… But there is only one species of finch on the mainland! Darwin asked: If the Galapagos finches came from the mainland, why are they so different now? Large ground finch Small ground finch Finch? Sparrow? Regents Biology Warbler finch Tree finch Woodpecker? Warbler?

The finches cinched it! different beaks are inherited variations serve as adaptations that help birds compete for food these birds survive & reproduce The finches cinched it! Darwin found: The differences between species of finches were associated with the different food they ate Large ground finch Big seed eater Small seed eater Small ground finch Regents Biology Warbler finch Insect eater Tree finch Leaf & bud eater

Relationship between species (beaks) & food Regents Biology

Darwin’s finches Darwin’s conclusions variations in beaks differences in beaks in the original flock adaptations to foods available on islands natural selection for most fit over many generations, the finches were selected for specific beaks & behaviors offspring inherit successful traits accumulation of winning traits: both beaks & behaviors separate into different species Regents Biology

From 1 species to 14 species… Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous Vegetarian Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground Insect eaters Bud eater Seed eaters Cactus eater Warbler Tree finches Ground finches natural selection for best survival & reproduction variation Regents Biology

Who is the Fittest? Who would survive the best in the arctic? A. Polar Bear B. Grizzly Bear C. Brown Bear

Darwin’s Great Journey While he was observing animals, Darwin discovered many things about the way animals adapt. He noticed: 1. Overproduction 2. Competition 3. Variation 4. Adaptation 5. Speciation

Overproduction Producing far more offspring than your environment can handle Leads to a struggle for survival.

Competition Each individual in an environment must compete in order to survive. For example – if we were stranded in the high school and they had a pizza in the gym, each person would compete to get there and eat before the rest of the class.

Fitness The ability an individual has to compete in an environment. For example – If you and Bear Grylls were stranded in Alaska, who is more fit to survive?

Variation Our genes make us different from one another. Variation gives a species a bigger chance of survival. For example – some humans are natural swimmers. If Long Island sank and we had to swim across to Connecticut, the swimmers would survive.

Adaptation Inherited characteristic that increases an organism’s chance of survival. For example – The mud skipper adapted the ability to breathe out of water because his habitat changed.

Speciation Formation of a new species For Example – before homo sapiens, homo rhodensiensis could not speak. A new species evolved that could speak called homo sapiens.