Evolution

Adaptations Variations are Differences in a species Example: long necks on giraffes Adaptation is When an organism becomes better suited to its environment Examples (give 3): Body Structure/Function Coloration Behavior

Adaptations

Geological Time Evolution is Change over a period of time and is based on present scientific data Evidence of evolution is found in remains called Fossils Formation of fossils: Imprint: formed from soft body parts Molds or casts: a cavity in the shape of the organism Petrified: hard parts replaced by minerals Amber: Hardened sticky plant resin (captures small organisms)

Geological Time Paleontologists They reasoned that the arctic was once Look for and study fossils They reasoned that the arctic was once Warm and humid (petrified forests)

Geological Time There are 3 eras: Paleozoic, Mesozoic, and Cenozoic The timeline of life that scientists made by studying fossils is the Fossil record There are 3 eras: Paleozoic, Mesozoic, and Cenozoic Each is broken down into periods. Then broken down into epochs. Precambrian period lasted 4 billion years and there is evidence of Bacteria and algae

Evidence for Evolution Homologous organs or body parts are Similar in structure Examples: forelimbs of whales, human arm, Hox Genes

Evidence for Evolution Analogous organs or body parts have Same function but different structure Examples: wing of fly vs. wing of bird

Evidence for Evolution Human appendix provides evidence of Evolution and the structure is called Vestigial

Evidence for Evolution Embryological evidence of vertebrates is similar in The early stages

Evidence for Evolution Biochemical evidence suggests that Living things share many of the same amino acids Molecular evidence suggests that the genetic code is nearly universal Biochemical and molecular evidence are studying the same thing!

Theories of Evolution Hutton and Lyell recognized that Earth is millions of years old, not thousands Processes that changed Earth in the past are still happening today These processes can explain how things can be built up or eroded away over millions of years

Theories of Evolution Example: giraffe long necks Lamarck’s Theory: believed that traits acquired in one generation could be inherited by the next Acquired = actions of the organism causes Example: giraffe long necks

Theories of Evolution Lamarck’s Theory

Theories of Evolution Darwin’s Theory of Natural Selection: organisms that are best suited to their environment survive and reproduce “survival of the fittest”

Theories of Evolution Darwin’s Theory based on 4 facts: Overproduction: To produce more offspring than could survive Struggle for existence: Competition for survival (food, water)

Theories of Evolution Darwin’s Theory based on 4 facts: Variations: Differences Natural selection & the Origin of New Species: Helpful variations, some neutral

Theories of Evolution

Theories of Evolution DeVries claimed that new species arose From “mutations”

Adaptive Shifts Changes in the frequency or occurrence of certain genes as environment changes Examples (give 2): peppered moth and black moth

Adaptive Shifts Changes in the gene pool of a population may also be a result of migration, which is the movement of an organism into or out of a population

Adaptive Shifts Isolation occurs when a population is separated from the other memebers of the same species As a result it is possible for speciation to occur Ex. Galapagos finches

Adaptive Shifts Divergent Evolution is where many different species develop from a common ancestor Ex: birds, whales, and bears Common ancestor

Adaptive Shifts Convergent Evolution is a process of unrelated species developing similar characteristics Ex: whales & porpoises, dolphins & sharks Unrelated species

Genetic Drift A random change in allele frequency is called genetic drift Bottleneck Effect: Change in allele frequency following a dramatic reduction in the size of a population Founders Effect: Allele frequency changes due to the migration of a small subgroup of a population

Genetic Drift Bottleneck Effect

Genetic Drift Founders Effect

Genetic Equilibrium Is when allele frequencies in a gene pool do not change for a population Hardy-Weinberg principle: Mathematically proves evolution 5 conditions that can disturb genetic equilibrium and cause evolution to occur:

1. nonrandom mating: individuals select mates sexual selection: genes for the selected for or against are not in equilibrium 2. small population size: evolution change due to genetic drift happens more easily in small population

3. immigration/emigration: individuals coming into a population bring new alleles, while individuals leaving a population remove alleles from the gene pool

4. mutations: can introduce new alleles into a gene pool Changes allele frequencies Causes evolution to occur 5. Natural Selection: genotypes that are better suited to an environment will disrupt genetic equilibrium causing evolution to happen.

Isolation Mechanisms: When some members of a population stop breeding with other members Gene pool splits

Reproductive Isolation Behavioral Isolation: differences in courtship rituals or other behaviors Geographical Isolation: when 2 populations are separated by geographic barriers Ex: rivers, mountains, bodies of water

Reproductive Isolation Temporal Isolation: when two or more species reproduce at different times Ex: flowers blooming

***Darwin’s Finches & Speciation*** Occurred by: Founding a new population, geographic isolation, changes in the new population’s gene pool, behavioral isolation, and ecological competition. You Better KNOW This!!!!

***Darwin’s Finches & Speciation***

***Darwin’s Finches & Speciation***

Rate of Evolution p. 549-552 Evidence shows: evolution occurs at different rates for different organisms at different times Gradualism: slow and steady evolution

Rate of Evolution p. 549-552 Punctuated Equilibrium: equilibrium interrupted by brief periods of more rapid change

Two Types of macroevoluation Adaptive Radiation: evolution over short time into different forms that live in different ways Modern Examples: Galapagos finches Finches evolved different beaks & behaviors to enable them to eat different kinds of food

Two Types of macroevoluation

Coevolution Coevolution: when two species evolve in response to changes in each other over time Examples: flowers/pollinators