Evolution Flashcards
Evolution
It’s not a linear progress
It’s not a March of Progress… It’s not linear
STEP #1
We’re all Different
Organisms that reproduce sexually produce genetically unique individuals.
• We are all slightly different from one another.
• New traits are brought about by new genetic combinations either from fertilization or from mutations
• New traits are called mutations
STEP #2 Environmental Changes
• If the environment changes some organisms will be more likely to survive
SELECTION PRESSURE–> something that favors certain traits over others
STEP #3 Survival of the Fittest
If the environment changes some organisms will be more likely to survive
• Not all mutations are beneficial.
– If a mutation helps an organism survive it is
called an adaptation.
– Not all mutations are adaptations.
STEP #4
Dead organisms don’t have sex
Those best adapted to the changed environment will survive to reproduce.
• Their offspring will inherit the gene for their adaptation.
Natural selection
Natural selection: process by which individuals with inherited characteristics well-suited to the environment leave more offspring on average than other individuals
SURVIVAL (and reproduction) OF THE FITTEST
So how did we get so much variation?
Descent with modification: Descendents of earliest organisms spread into various habitats over million of years. In these habitats they accumulated different modifications or adaptations to diverse ways of life example Jack rabbits/snow rabbits
Evidences of evolution
Comparative Anatomy Vestigial Organs Embryo Studies Fossil Evidence Biochemistry -Amino Acid Sequences and DNA studies
Comparative anatomy
The more similar in structure 2 organisms are the closer related they are.
Two types of structures
Analogous Structures:
Same FUNCTION, Different STRUCTURES
WHAT ARE SOME EXAMPLES?
Homologous Structures:
Same STRUCTURE, Different FUNCTIONS
WHAT ARE SOME EXAMPLES?
Not evidence analogous structures
Structures that have the same function but developed differently.
Evidence for evolution homologous structures
Structures that have different functions but developed similarly.
Vestigial organs
Organs that no longer have a purpose
Tailbone 4. Tonsils
Appendix 5. Wisdom Teeth
Body Hair 6. Little Toes
Embryo studies
The more closely related 2 organisms are the more similar their embryo development.
Pangea: Moving Continents
Similar fossils found in different parts of the world suggest those fossils were once together
WHY IS
THIS
EVIDENCE?
