Exam 1 Flashcards
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Define population genetics.
Genetic differences within and between populations.
Define allelic frequency.
Fraction of all chromosome frequencies in a population.
Define genotype frequency.
Number expressed as a percent of individuals with a specific genotype.
Define Phenotypic frequency.
Number expressed as a percent of individuals in a population who express a specific phenotype.
Define Hardy-Weinberg equilibrium.
Genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
Five agents of evolutionary change.
Genetic drift, non random mateing, mutation, gene flow, natural selection.
What is genetic mutation?
Random change in a gene making it different from the parent gene.
What is gene flow?
The movement of genetic material from one population to another.
What is non random mateing?
When the chances of mating with a specific trait are higher then others.
What is genetic drift?
in a small population gentic variation can disappear due to chance occurrences.
Define evolution.
Change in heritable characteristics of populations over successive generations.
Define natural selection.
Organisms best adapted to their environments tend to survive and transmit their genetic information.
What is Darwin’s theory?
All species and organisms arise from natural selection of an individual’s ability to survive and reproduce.
What is Lamarcks theory?
Physical changes in an organism can be transmitted to offspring
Criteria necessary for natural selection to occur.
1) genetic variation must exist
2) genetic variation much be heritable
3) organism must survive to pass genetics to offspring.
Define fitness.
Organisms ability to survive mate and produce offspring.
What is selection pressure?
External agents which affect an organisms ability to survive in a given environment.
3 Types of selection.
- Stabilizing Selection (section against extremes)
- Directional Selection (selection towards one extreme)
- Disruptive Selection (selection towards extremes)
Define artificial selection.
Intentional breeding of plants and animals for select traits.
Describe heterozygous advantage.
The case in which heterozygotes have a higher fitness then homozygotes.
Define sexual selection.
Selection which sexes acquire distinct forms.
Define intrasexual selection.
Members of the same sex compete for mates.
Define Intersexual selection.
Females choose mates.
Define convergent evolution.
Species developed the same traits due to being exposed to the same selective pressures but do not come from a common ancestor.
Define divergent evolution.
Species with a same common ancestor evolve differences resulting in a new species.
Define adaptive radiation.
Organisms diversify and change rapidly to fill open niches.
Describe the biological species concept.
Group of Organisms that are reproductively isolated from other groups of organisms
Describe the process of speciation.
When groups in a species become reproductively isolated from the rest of the group and become genetically different from the rest.
What is the importance of reproductive isolation in the terms of speciation.
When a group is reproductively isolated from the rest of the population mutations occur and stabilize in a population making them genetically different from the rest.
Define allopatric speciation.
When a species becomes geographically isolated from eachother and prevents gene flow between the population’s.
Define Sympatric speciation.
Speciation occurs within a population due to new niches becoming available and causing reproductive isolation.
Describe vicariance derived allopatric speciation.
When a population is divided by the appearance of a geological barrier.
Describe dispersal derived allopatric speciation.
Occurs when a group of a population crosses a barrier that already exist.
Describe polyploidy speciation
Instantaneous speciation can occur when offspring is born with more chromosomes then the rest of the population, reproductively isolating them from the rest of the population.
Define prezygotic reproduction isolation
Mechanism that Prevents the fertilization of an egg.
Define postzygotic reproductive isolation.
Mechanism preventing the formation of a fertile, and or viable offspring.
3 postzygotic isolation Mechanism
1) hybrid inviability
2) hybrid sterility
3) hybrid breakdown
5 prezygotic isolation mechanisms
1) ecological isolation (ex; eats different stuff, lives in tree vs on ground)
2) temporal isolation (sexually active at different times)
3) behavioral isolation (mating dances, displays of color ect)
4) mechanical isolation (penis does not fit into vagina)
5) geographical isolation ( not in the same area)
3 problems with the biological species concept.
1) is not applicable to fossil species
2) not applicable to asexually reproducing species
3) not applicable to species with open mateing systems.
Define taxonomy
The science of nameing defining and classifying groups of organisms baised on shared characteristics.
Describe the taxanomical hierarchy from largest to smallest
Domain Kingdom Phylum Class Order Family Genus Species
Define phylogeny
The evolutionary history and development of a species or group of organisms.
Define systematics
The study of the diversification of living forms and their relationships
Define clade
A grouping that includes a common ancestor and all descendants
Define monophyletic grouping
Group that includes all descendants of the most recent common ancestor
Define paraphyletic group
Group that includes an ancestor but not all of its descendants.
Define polyphyletic group
Groups that does not share a common ancestor
Define homology.
Similarity in structure, physiology or, development of different species baised upon their decent from a common ancestor.
Define analogy.
Similarity in function or resemblance of structures in organisms that have different ancestor origins
Define homoplasy.
A trait shared by a set of species that is not present in their common ancestor.
What is the principal of parsimony?
Given a set of possible explanations, the simplest explanation is the most likely to be correct.
How are fossils created?
An organism dies in a wet area and is covered by mud or silt. The soft bits decay and bones or shells are left and covered in hardened build up sediment.
How are fossils relatively dated?
Compared to rocks and fossils of a known age.
How are fossils absolutely dated?
Useing the half life of radioactive elements, a precise range can be made as to how old a fossil is.
How are fossils used as evidence for evolution?
Comparing fossils to live organisms can show how change has occurred through time.
What are the domains used to classify prokaryotes?
Bacteria and archaea.
Difference between prokaryotic and eukaryotic cells?
Prokaryote cells do not have:
- a nucleus
- membrain bound organelles
- mitochondria
What is the general structure of a bacterial cell?
- capsule(outside of cell)
- cell wall
- cytoplasmic membrain
- cytoplasm
- nucleoid
- scillia or flagella (locomotion)
- pili (hairs on outside of cell)
- ribosomes
Difference between gram positive and negative forms of bacteria.
Gram+ have a thick peptidoglycan layer and no outer lipid layer. Gram- have a thin peptidoglycan layer and do have an outer lipid layer.
How does genetic variation occur in prokaryotes?
Transformation- the take up of dna floating in environment.
Transduction- dna is moved from one to another by a virus
Conjugation- dna is transferred by tube between 2 cells
Mutation- random errors in replication.
Differences between bacteria and archaea?
- Different ribosomal RNA
- Archaea dont have peptidoglycan in cell walls
- archaea use ether linked lipids in cell membrain, bacteria use ester linked lipids.
What are protists?
Organisms that dont belong in any catagory of taxonomy and are out into protista. Protists include protozoa, unicellular algae and slime molds.
7 super groups of eukaria.
Excavates Alveolates Stramenopiles Amebozoans Rhizarians Archaeplastids Opisthokonts
Characteristics of Excavates?
Unicellular Heterotrophic Altered mitochondria Unusual flagella Cannot make ATP
Describe characteristics of Alveolates.
Sacs of fluid under the cell membrain called alveoli
Describe characteristics of Stramenopiles.
Textured or hairy flagellum
Additional smooth flagellum
Describe characteristics of Amoebozoans.
Pseudopodia (foot for movement)
Describe characteristics of Rhizarians
Thread like or needle like pseudopodia.
Describe characteristics of Archaeplastids
Cells lack cenrioles
Mitochondria with flat cristae
Describe characteristics of Opisthokonts
Propelled by a single Flagellum. (Animal sperm)
