Evolution Flashcards
What are Homologous structures?
Similar structures, different functions
What is divergent evolution?
When structures adapt by natural selection to do different functions
ex. whale fin vs bat wing
Homologous =
Divergent
Analogous =
Convergent
What are Analogous Structures?
Looks different, same function.
ex. wings
Can shape different species into similar forms because of their environment
What is convergent evolution?
When organisms that aren’t closely related, have similar features/behaviors
Ways that natural selection alters the allelic frequency?
- Directional selection
- Disruptive selection
- Stabilizing selection
What is Directional Selection?
Favours one extreme of the phenotype
ex. peppered moths
What is Disrupted Selection?
Favours both extremes of the phenotype
ex. big and small salmon
What is Stabilizing Selection?
Favours the intermediate phenotype
What is sexual selection?
Traits that are inherited to attract a mate
What is sexual dimorphism?
Differences in secondary sexual characteristics between males and females of the same species (ex. small females, big males)
What is intrasexual selection?
Competition within the same sex
What is intersexual selection?
Sexual selection between the sexes
ex. long feathered peacocks
What is balancing selection?
Maintains two or more phenotypes forms in a population
What is frequency-dependent selection? ex. left mouth fish vs right mouth fish
When two phenotypes go back and forth depending on which was higher the previous generation
ex. (favours whichever was least common that year)
What is heterozygote advantage?
When heterozygous individuals have a greater relative fitness compared to homozygous individuals
What are the 4 conditions that made life on earth possible?
- The abiotic synthesis of small molecules (amino acids and nitrogenous bases)
- Joining of molecules into macromolecules (due to the hot surfaces)
- Packaging of these molecules into protocells
- The origin of self-replicating molecules
What is most likely the first genetic material?
RNA
What are sedimentary rocks?
The richest source of fossils
How are rocks dated?
Using Radiometric dating
What is radiometric dating?
Use of radioactive isotops to measure the half life.
Comparing carbon-14 to carbon-12 ratios to determine age
Where did mammals originate?
A group of tetrapods called synapsids
What is the order of the Geological record?
- Prokaryotes
- Atmospheric oxygen
- Single celled eukaryotes
- Multicellular eukaryotes
- Animals
- Colonization of land
- Humans
What are the consequences of mass extinction? (SER)
1.Reduces large number of species
2. Reduces the ecological community
3. Species cannot reappear
What is mass extinction?
The loss of many species over a large expanse in a short amount of time
There have been 5 mass extinction events in earths history
Benefits of mass extinction?
- Adaptive radiations
What are adaptive radiations?
Organisms that form new species in a short amount of time with adaptations to help them survive in environments their ancestors couldn’t
