Unit 7: Natural Selection Flashcards
(AP key concepts)
When does speciation occur?
When population are reproductively isolated from each other.
What is the biological species concept?
Species are a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring.
What is punctuated equilibrium?
Evolution occurs rapidly after a long period of stasis, periods of minimal to no change.
What is gradualism?
Evolution occurs slowly over hundreds/thousands/millions of years.
What is allopatric speciation?
Evolution of new species through the process of geographic isolation over a long period of time.
What is sympatric speciation?
Evolution of a new species due to individuals being reproductively isolated from a surviving ancestral population.
How do pre-zygotic mechanisms impact speciation?
They prevent sperm and egg from meeting
How do post-zygotic mechanisms impact speciation?
They prevent a zygote from developing into a viable, fertile offspring.
What is speciation?
The creation of new species.
What does speciation result in?
Diversity of life forms.
What are the effects of allopatric speciation?
No gene flow. Exposes populations to different selection pressures.
What are the characteristics of sympatric speciation?
No geographic barrier. Can result from genetic mutations, polyploidy, habitat differentiation, and sexual selection.
What is the stimulus for evolution?
Changing ecological conditions.
What is adaptive radiation?
Evolution of new species that allows empty ecological roles or niches to be filled.
What factors lead to extinction?
Catastrophic changes to an ecosystem; Human activity; Invasive species.
How do environmental changes increase risk of extinction?
Mass destruction can result in habitat loss. Catastrophic events can wipe out many organisms.
How do speciation and extinction rates impact species diversity?
High species biodiversity can result from high levels of speciation and low levels of extinction and vice versa.
How does extinction create new niches?
When a species goes extinct, it leaves an open niche for another species to occupy.
What is extinction?
Complete disappearance of a species
What are the 5 pieces of evidence that support evolution?
geological- fossils; changes of environmental feature
geographical
physical- phenotypes
biochemical- chemical composition of living things
mathematic
How are fossils dated?
dated through age of rock
decay of isotopes
geological data
What demonstrates common ancestry for eukaryotes
membrane bound organelles
linear chromosomes
genes with introns
Lamarck Evolution
evolution through inheritance of acquired traits
Darwinian evolution
natural selection
–> mutation: longer neck giraffes survived and shorter neck died