Evolution Flashcards
The change in allele frequencies in a population over time
Evolution
Alleles are the _____ _____ of a particular genetic trait
Different variation/forms
Who was
- a French naturalist
- 1809 published ideas on evolution
- had a (false) hypothesis named after himself
Jean Baptiste Lamarck
Lamarck’s Hypothesis:
- During an organism’s lifetime , physical feathers would ____ in size because of use or ____ in size because of disuse
- organisms pass down _____ traits to offspring
Increase, decrease, acquired
Who thought
- human population was increasing faster than supply of resources
- population growth is limited by disease, famine, and war
Hint : AP HUG
Thomas Malthus
Who was
- a leading geologist of Darwin’s time
- surface of the Earth changed slowly over a long period of time
Charles Lyell
Who was
- a 22 year old HMS naturalist
- spent 5 years observing and collecting 100s of plants and animals from jungles , grasslands, desert, etc
Charles Darwin
After the voyage Darwin concluded that
Variations within some species enable some to survive and reproduce while those with other variations do NOT survive or reproduce
Selective breeding of plants /animals with desirable traits
Artificial selection
Organisms with favorable variations for a certain environment will survive , reproduce, and pass these variations to offspring .
“ survival of the fittest “
Natural selection
Ability of an organism to survive and reproduce in it’s specific environment
Fitness
Any trait that aids the chances of survival and reproduction
Adaptation
What are the 3 types of adaptations ?
- Structural adaptations
- Physiological adaptations
- Behavioral adaptations
What type of adaptation is this :
Changes in the structure of organism’s body parts
E.g., thorns, camouflage, mimicry
Structural adaptations
What type of adaptation is this :
Changes in organisms metabolic processes (jobs body parts )
E.g., super kidneys
Physiological adaptations
What type of adaptation is this :
Changes in organisms response to the environment. Can be learned behaviors or instinctual
E.g., spinning webs , danger signals ,mating rituals ,hibernation
Behavioral adaptations
What is a fossil?
A fossil is any evidence of an organism that lived years ago
What is a paleontologist ?
Scientists who study ancient life and fossils
Most fossils are located in
Sedimentary rock
What determines fossil formation ?
The environment
What are the two ways to date fossils ?
Relative dating and radiometric dating
*Modified structure in different groups of organisms.
* Similar structure, but may have same / different function
* Implies common ancestor
Homologous
- structures with similar function, but different structure
- Shows evolution
- NOT common ancestor
Analogous structures
- structure / organs appear to have little / no use
- May have been used in ancestor
- Indicate evolution
Vestigial structures
- many different animals - same organs as embryos
- Suggest common ancestor
Embryology
Similarities in ___ / ____ sequence . Shows evolutionary relationships
DNA / RNA
Population in which allelic frequency does NOT change over generations
Genetic equilibrium
What are the two main sources of genetic variation ?
Mutation and gene shuffling
- any change in a sequence of DNA
- Caused by mistakes during replication or environmental factors such as radiation or chemicals
- Sources or new phenotypes
Mutations
- mixing of gene during the production of gametes in meiosis
- Recombination ( aka law of Independent Assortment) as homologous chromosomes move independently during meiosis
- Crossing over : the exchange of genetic material during prophase I
Gene shuffling
Entire collection of all the alleles in a population
Gene pool
The number of times an allele appears in the gene pool
Allelic frequency
The change in allele frequency occurs in 3 ways
- gene flow
- Genetic drift
- Natural selection
- the movement of allele into or out of a population of* population’s genetic variation increase when alleles are added to the population ( migration )
- Decrease when alles have ( emigration )
Gene flow
Random change in allelic frequencies due to chance
Genetic drift
What are the two kinds of genetic drift?
Founder effect and bottleneck
*A small group of individuals colonize a new habitat
* Alleles frequencies change due to the random change in the population
Founder effect
- a sharp reduction in the size of a population due to the environmental events ( flooding, earthquake, etc )
- Alle frequencies change due to the random change of surviving the bottleneck event
Bottleneck
Most common source of evolutionary change. Can lead to a increase or decrease in allele frequency I’m single gene traits. Affects are complex in polygenic traits.
Natural selection
One of the extreme phenotype e is selected against
Directional selection
BOTH of the extreme phenotypes are selected against. E.g., baby’s birth weight
Stabilizing selection
The middle phenotype is selected against . E g., Large and small bid beak
Disruptive selection
Natural selection is the key mechanism of evolution that leads to
Specification ( new species )
What is a species ?
A group of organisms that
- can interbreed
- produce fertile offspring
- mate in nature
____ is the evolution of a new species
Speciation
____ is the loss of species
Extinction
Speciation in occurs when
- formerly interbreeding organisms are prevented from mating and producing fertile offspring
- this is called reproductive isolation
Reproductive isolation can lead to speciation in 3 ways. Name all 3
- geographical isolation
- temporal Isolation
- behavioral isolation
- occurs if a physical barrier separates a population into groups
- can be created by any type of physical barrier ( mountains, rivers, even highways )
Geophysical isolation
- temporal means “time “
- occurs when timing prevents reproduction between populations
E.g., seasonal differences in mating habits- one mates in the spring , the other in the fall
Temporal isolation
Caused by differences in courtship or mating rituals
Behavioral isolation
Speciation can occur ____ or ____
Slowly or quickly
Gradualism means
Slow and steady change
- stable period ( stasis ) interrupted by rapid changes
- caused by change in environmental conditions
- also supported by fossil evidence
Punctuated equilibrium
Species with ____ when introduced to a new environment
Diversity
- develops into 2 or more distinct species
- also called divergent evolution
- due to natural selection
Adaptive radiation
- the pattern of evolution is which unrelated organism evolve similar traits
- due to similar environments and similar selection pressures
E.g , dolphins and fish
Convergent evolution
