Basic concepts evolution etc. Flashcards
What’s the difference between the scientific and colloquial use of the word theory?
Colloquial theory is a possible explanation unsupported by evidence
Scientific theory is an idea supported by evidence that has not been previously disproven
Define evolution
Descent with modification; a change in the genetic composition of a population from generation to generation
Define microevolution, provide an example
Small, subtle changes within a population within a short amount of time
Ex;
Medium ground finches
Define macroevolution, provide an example
A large, dynamic change at or above the species level over a long time.
This results in speciation and a change in a line of descent
Ex;
Initial galapagos finches speciation into 13 different species
What is the difference between natural, artificial, and sexual selection?
a variation in heritable traits that ….
Natural selection: promote survival and reproduction due to environmental selection pressures
Sexual selection: A variation in traits determined by intra and inter sexual selection to increase reproductive success
Artificial selection: determined by human selection pressures
Dog breeders
What are the two types of sexual selection, provide examples
ntrasexual selection: pressures of the same gender
Males competing w/ males for the right to reproduce with females.
Ex; bigger claws, bigger body sizes, lions mane (intimidation), aggression
Intersexual selection: pressures of the other gender
Males proving to females that they are healthy, have good genes, and have surplus energy. If too exaggerated may lead to death.
Ex; peacock feathers, strong male calls (frogs), elephant spider’s butt & dancing. Female generally involves having more oovum
Define reproductive success
Total sum of offsprings an individual organism has within its lifespan
Define adaptation
Any trait or characteristic (mutated or inherited) that promotes or favors survival and/or reproduction
What is the difference between homologous, analogous, and vestigial structures?
Homologous: similar traits due to a common ancestor with the same trait, derived from the same anatomical structures or tissues
Ex; tetrapod forearms
Analogous: convergent evolution, similarity in form and structure of two structures not due to a common ancestor but due to similar selection pressures
Ex; moths, bats, and birds both have wings
Vestigial: leftover structures due to … reduced selection pressures and/or reduced function
Ex; coccyx in humans, phalanges in most birds
What is heterozygosity and homozygosity, and how do they relate to genetic variation?
The number of individuals with … traits on their loci
Heterozygosity: heterozygous traits, increase genetic variation
Homozygosity: homozygous traits, decrease genetic variation
Difference between convergent and divergent evolution
Convergent evolution: aka analogous evolution / characteristics, is different species adapting similar traits due to similar selection pressures
Divergent evolution: species adapting dissimilar traits and undergoing speciation, the development of new species over time due to selection pressures
Can you provide evidence to support the theory of evolution?
microevolution: Darwins finches, antibiotic resistant bacteria.
Homologous proteins: RuBisCo
Fossils, biogeography, & continental drift
Define population
A group of individual organisms in the same species in a given area that interbreed
Define gene pool
All the genes, including all the different alleles for each gene, that are present in a population at any one time
Define population genetics
The study of gene frequencies in a population (microevolution)
Define relative fitness
How well an individual organism survives and reproduces RELATIVE to others in the population
What are Hardy Weinberg’s
5 assumptions?
Very large population
No new mutations
No migration (emigration or immigration)
No natural selection
No sexual selection
Define, draw, and give an example of directional selection
Selection pressures favor one extreme phenotypic trait, thereby shifting the frequency distribution of one phenotypic range either higher or lower. Commonly occurs due to environmental changes.
Medium Galapagos finches
Define, draw, and give an example of stabilizing selection
Negative selection pressures exist at both phenotypic extremes, favoring intermediate phenotypes. Reduces variation.
Human baby body weight
Define, draw, and give an example of disruptive/divergent selection
Selection pressures favor both extreme phenotypes, and negatively select for intermediate traits. Aka dimorphism.
Peppered moths & cameroon finches
Define, draw, and give an example of frequency-dependent selection
Selection pressures favor the rare phenotype in a population, which will switch between the dimorphic phenotypes
P. microlepis, parasitic fish (left fish and right fish)
Which one of the four selection pressures most often results in speciation?
- Directional: most likely due to its relation to microevolution
- Disruptive: usually it just results in dimorphic species that still mate with each other, unless the phenotypic range is great enough for the longest time or an environmental change
- Stabilizing: reduces genetic variation, so very unlikely
- Frequency-dependent: traits and adaptation is inherently circular, therefore evolving in one way is nearly impossible
Define canalize
Driving the average frequency of a trait down, otherwise known as a negative selection pressure
Define polymorphism and what causes it
The movement of alleles into and out of a population due to immigration or emigration
Insect pollination
Contributes to balancing out species wide genetic diversity and heterozygosity
Define gene-flow
The movement of alleles into and out of a population due to immigration or emigration
Insect pollination
Contributes to balancing out species wide genetic diversity and heterozygosity
Define genetic drift
and its consequences
Change in allele frequencies, a loss or gain, due to a random chance event. Usually negatively affects and constrains evolution by damaging genetic variability by destroying beneficial alleles. Occurs in small pop’ns.
Sometimes, by chance, future evolution is compromised
Ex;
Typhoon hits an island, and a bunch of lizards die. The genes that were lost were random and didn’t represent the selection pressures, and the remaining lizards had a lesser frequency of adaptive traits … go extinct
Define bottleneck effect
and its consequences
A sudden, indiscriminate change in the environment (not a chance event) that may drastically reduce the size of a population - and the remaining genes weren’t adaptive.
Occurs over a generation in relatively large pop’ns
Ex;
Illinois prairie chicken pop’n was reduced over 100 years and the remaining chickens had high frequencies of recessive diseases
Define founder effect
and its consequences
When a few individual organisms get isolated and gene flow between the isolated and the rest of the population, the consequences are an evolutionary limitation due to the genes first introduced, homozygosity, and inbreeding.
Anolis segrei (bahamas lizard)
