Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Hologenome theory of evolution wikipedia , lookup
Sexual selection wikipedia , lookup
Saltation (biology) wikipedia , lookup
Natural selection wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
Theistic evolution wikipedia , lookup
On the Origin of Species wikipedia , lookup
Starter #46 and Objectives Table of Content: Darwin’s Theory of Evolution by Natural Selection • Starter: What do you think of when you think of the word Evolution? • Objectives: –Explain the process of Evolution by Natural Selection Homework and Reminder Homework: None but there is a writing assignment I’ll tell you at the end of class Reminder: Cell phone should be off and out of sight! Evolution •Evolution is the change in the allele frequency and heritable characteristics of a population over many successive generations over time. 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 – 1809-1882 – British naturalist 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 Robert Fitzroy Voyage of the HMS Beagle • Stopped in Galapagos Islands – 500 miles off coast of Ecuador 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. 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? Darwin found…clues in the fossils Darwin found: Evidence that creatures have changed over time present day Armadillos Darwin asked: Glyptodonts ancient Armadillo Why should extinct armadillos & modern armadillos be found on same continent? Darwin found… more fossils Darwin found: Evidence that creatures have changed over time present day Sloth (extinct) Giant ground sloth Darwin asked: Why should extinct sloths & modern sloths be found on the same continent? Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like? Darwin found… birds Darwin found: Many different birds on the Galapagos Islands. He thought he found Finch? very different kinds… Sparrow? QuickTime™ and a Photo - JPEG decompressor are needed to see this picture. Woodpecker? Warbler? But Darwin found… a lot of Darwin was amazed tofinches find out: All 14 species of birds were finches… But there is only one species of finch on the mainland! Large ground Small ground Finch? Sparrow? Finch? Sparrow? QuickTime™ and a - JPEG decompressor finch arePhoto finch needed to see this picture. Darwin asked: If the Galapagos finches came from the mainland, why are they so different now? Warbler finch Woodpecker? Woodpecker? Tree finch Warbler? Warbler? The finches cinched it! different beaks are Darwin found: inherited variations The differences serve as adaptations between species of that help birds said: compete Darwin finches were for food associated with the Ahaaaa! these birds survive & different food they Big Aeater flock of South Large seed ground Small Small seed ground eater Finch? Sparrow? reproduce ate. finch finch American finches QuickTime™ and a Photo - JPEG decompressor are needed to see this picture. pass on the genes for were stranded on the those more fit beaks Galapagos… over time nature selected for different species with different beaks Warbler Insect eater finch Woodpecker? Leaf Tree & bud finch eater Warbler? Relationship between species (beaks) & food 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 From 1 species to 14 species… Warbler finch Cactus finch Woodpecker finch Sharp-beaked finch Small insectivorous tree finch Large insectivorous tree finch Small ground finch Cactus eater Insect eaters Seed eaters Vegetarian tree finch variation Bud eater Medium ground finch Large ground finch natural selection for best survival & reproduction Earlier ideas on Evolution • LaMarck – evolution by acquired traits • creatures developed traits during their lifetime • give those traits to their offspring – example • in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring – not accepted as valid Darwin’s view of Evolution • Darwin – giraffes that already have long necks survive better – leave more offspring who inherit their long necks •variation •selection & survival •reproduction & inheritance of more fit traits Natural Selection Darwin developed the idea of: natural selection – organisms with favorable traits are more likely to survive and reproduce; “survival of the fittest” Natural Selection fitness – combination of physical traits and behaviors that allow an organism to be more successful in its environment adaptation – any inherited characteristic that increases an organism’s fitness for survival Natural Selection Lamarck – thought acquired traits could be passed on to future generations ex: giraffe neck length • Darwin published this • work to explain the variety of species that exist on the planet He proposed the “Theory of Evolution by Natural Selection” 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….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. That is NATURAL SELECTION. 1.Variation 2.Competition 3.Survival 4.Reproduction Asking Questions is a good adaptation! 2006-2007