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 Theory?

Regents Biology What we know, so far….  Many different species alive today  All life shares common characteristics  The Earth is very old  Life is very old  Life has changed over time  The changes have been little changes over long periods of time Evolution But how does this work?

Regents Biology DNA Evolution explains Unity & Diversity  Only evolution explains both  unity of life  similarities between all living things  diversity of life  wide variety of different creatures on Earth

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 Robert Fitzroy Voyage of the HMS Beagle  Invited to travel around the world  makes many observations of nature  main mission of the Beagle was to chart South American coastline

Regents Biology Voyage of the HMS Beagle  Stopped in Galapagos Islands  500 miles off coast of Ecuador

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 Darwin asked: Is there a relationship between the environment & what an animal looks like?

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  Speciation- process by which new species arise  Separate into different species

Regents Biology The finches cinched it for Darwin

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

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 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

Regents Biology 5 Principles of Natural Selection  heritable variation variation exists in populations (we are all different!)  over-production of offspring  more offspring than the environment can support  competition  for food, mates, nesting sites, escape predators  differential survival  successful traits = adaptations  differential reproduction  adaptations become more common in population

Regents Biology Survival & Reproduction of the fittest not the strongest… not the bravest… not the fastest… not the biggest… …the fittest! the traits that help an organism fit the environment better to survive & reproduce the traits that help an organism fit the environment better to survive & reproduce Adaptations

Regents Biology Darwin called this… or (change in species over time) Darwin concluded: Each species has descended, with changes, from other species over time. Descent With Modifications

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  Artificial selection  human caused evolution

Regents Biology 1. 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 Law of Superposition  The deeper you dig, the farther back in time you go.  The bottom layer is the oldest.

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

Regents Biology Land Mammal ? ? ? ? Where are the intermediate fossils? Ocean Mammal Someone’s idea of a joke! But the joke’s on them!! Complete series of transitional fossils We found the fossil — no joke!

Regents Biology Evolution from sea to land  2006 fossil discovery of early tetrapod  4 limbs  Missing link from sea to land animals

Regents Biology 3. 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 (anatomical structures)  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  Convergent evolution!! Solving a similar problem with a similar solution How is a bird like a bug?

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  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 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  human tail bone

Regents Biology Comparative embryology  Development of embryo tells an evolutionary story  similar structures during development all vertebrate embryos have a “gill pouch” at one stage of development

Regents Biology 3. Molecular record LampreyFrogBird Dog MacaqueHuman  Comparing DNA & protein structure  everyone uses the same genetic code!  DNA  compare common genes  compare common proteins  compare common genes  compare common proteins number of amino acids different from human hemoglobin

Regents Biology Phylogeny! Building “family” trees Closely related species are branches on the tree — coming from a common ancestor

Regents Biology  How do we know natural selection can change a population?  we can recreate a similar process  “evolution by human selection” 4. Artificial selection “descendants” of wild mustard

Regents Biology Selective Breeding Humans create the change over time “descendants” of the wolf

Regents Biology Artificial Selection …and the examples keep coming! I liked breeding pigeons!

Regents Biology Artificial Selection gone bad!  Unexpected consequences of artificial selection Pesticide resistance Antibiotic resistance

Regents Biology Insecticide resistance  Spray the field, but…  insecticide didn’t kill all individuals  variation  resistant survivors reproduce  resistance is inherited  insecticide becomes less & less effective  Genetic Drift!

Regents Biology