Regents Biology by Natural Selection Evolution…

Regents Biology What is Evolution?  Evolution  changes in living organisms over time  explains how modern organisms have descended from ancient organisms Why do we accept this as a Scientific Principle?

Regents Biology What do we know?  There are many different creatures on Earth How did all these creatures come about? What accounts for all this biological diversity? Biodiversity of Life on Earth

Regents Biology What do we know?  All creatures have common characteristics DNA cells Unity of Life on Earth How could all of life have the same basic features?

Regents Biology Evidence supporting evolution  Fossil record  shows change over time  Anatomical record  comparing body structures  homology & vestigial structures  embryology & development  Molecular record  comparing protein & DNA sequences

Regents Biology Fossil record  Layers of rock contain fossils  new layers cover older ones  creates a record over time  fossils show a series of organisms have lived on Earth  over a long period of time

Regents Biology What has the fossil record shown us?  Many creatures that lived in the past don’t exist today Origin of new species OBSERVATION

Regents Biology What has the fossil record shown us?  The creatures alive today haven’t always been around Different species lived in the past OBSERVATION

Regents Biology What has the fossil record shown us?  Many creatures in the past looked like living ones we see today “Family Tree” Relatives with similar, but not the same traits “Family Tree” Relatives with similar, but not the same traits OBSERVATION

Regents Biology Fossils tell a story… the Earth is old Life is old Life on Earth has changed

Regents Biology Anatomical record Animals with different structures on the surface But when you look under the skin… It tells an evolutionary story of common ancestors

Regents Biology Compare the bones  The same bones under the skin  limbs that perform different functions are built from the same bones How could these very different animals have the same bones?

Regents Biology Homologous structures  Structures that come from the same origin  homo- = same  -logous = information  Forelimbs of human, cats, whales, & bats  same structure  on the inside  same development in embryo  different functions  on the outside  evidence of common ancestor

Regents Biology But don’t be fooled by these…  Analogous structures  look similar  on the outside  same function  different structure & development  on the inside  different origin  no evolutionary relationship

Regents Biology Analogous structures  Dolphins: aquatic mammal  Fish: aquatic vertebrate  both adapted to life in the sea  not closely related Watch the tail!

Regents Biology Vestigial organs  Structures on modern animals that have no function  remains of structures that were functional in ancestors  evidence of change over time  some snakes & whales have pelvis bones & leg bones of walking ancestors  eyes on blind cave fish

Regents Biology Vestigial Organs  Examples:  Human tail bone-but no tails  Appendix  Ostrich wings-they don’t fly!

Regents Biology Vestigial organs  Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? Because they used to walk on land!

Regents Biology  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 Earlier ideas on Evolution

Regents Biology Alred Russel Wallace  Very similar views and conclusions as Darwin…  “Use variations will tend to increase, unuseful or hurtful variations to diminish”  “Those that die must be the weakest-the young, old, diseased-those that prolong their existence will be in most perfect health”

Regents Biology Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches Darwin & Evolution by Natural Selection

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   British naturalist

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

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

Regents Biology Darwin found: Different shells on tortoises on different islands

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 Finch?Sparrow? Woodpecker? Warbler? Darwin found… birds Finch?Sparrow? Woodpecker? Warbler? Darwin found: Many different birds on the Galapagos Islands. He thought he found very different kinds…

Regents Biology Darwin was amazed to find out: All 14 species of birds were finches… Finch?Sparrow? Woodpecker? Warbler? Finch?Sparrow? Woodpecker? Warbler? But Darwin found… a lot of finches Large ground finch Small ground finch Warbler finchTree finch But there is only one species of finch on the mainland!

Regents Biology Finch?Sparrow? Woodpecker ? Warbler? But Darwin found… a lot of finches Darwin asked: If the Galapagos finches came from the mainland, why are they so different now? Finch?Sparrow?