Midterm 2 Flashcards
The Hardy-Weinberg Equilibrium requirements
1) No mutations
2) No natural selection
3) No gene flow (no migration)
4) No genetic drift (which requires an infinitely large population size)
5) Random mating
Mendel’s Law of Segregation
When any individual produces gametes, the two copies of a gene separate so that each gamete receives only one copy
Mendel’s Law of Independent Assortment
alleles of different genes assort independently of one another during gamete formation, haploid gametes
Mitosis
Duplicate, all cells except sex cells, identical
Meiosis
Two stages of duplication, not identical to parent cell, only sex cells
Types of Dominance
Complete Dominace, Incomplete Dominance, Codominace
Complete Dominance
A single dominant allele produces the dominant phenotype. The homozygous dominant and heterozygous genotypes have the same phenotype
Incomplete Dominance
the heterozygote phenotype is intermediate between the two homozygous phenotypes
Codominance
the heterozygote shows both the homozygous phenotypes
Recombination
gene crossing over
Linkage
only crossovers happening in a small region
* Recombinant chromosomes do form, but not very often!
Recombination Frequency - eq.
recombinant frequency = recombinants / total offspring
Linkage Mapping
Determining the recombination frequency for numerous genes allows mapping each genes’ location on the chromosomes
Sex-linked inheritance
Females are less likely to exhibit sex-linked inheritance but can be carriers
Pleiotropy
When one gene affects multiple traits
Polygenic Inheritance
One trait is controlled by many genes
Environmental Influences
pH, food abundance, temperature, etc.
Epistasis
When multiple genes interact to determine the phenotype
allele frequencies
the proportion of a particular allele across all individuals, or in the gametes produced by those individuals
- dominant allele
- recessive allele
Genotype frequencies
the proportion of individuals with a particular genotype in a population homozygous dominant homozygous recessive heterozygous hemizygous
Allele frequencies equation
p(dominant) +q(recessive) = 1
Genotype frequencies equation
two alleles -> (p+q)^2
p^2 + 2pq + q^2 = 1
p^2 ( Homozygous dominant) + 2pq (Heterozygous) + q^2 (Homozygous recessive) = 1
three alleles -> (p+q)^3
What is Mutation?
BIS 2A
- Substitution
- Insertion and deletions
- Chromosomal Rearrangements
ex. unequal crossover
Gene Flow (migration)
transfer of alleles through movement of fertile individuals of their gametes
- immigration - into pop
- emigration - out of pop
Gene Flow vs. Migration
Sessile organisms migrate when individuals post fertilization can move before settling down
Inbreeding
mating between relatives with similar genotypes
ex. Charles 2 of Spain
Outbreeding
mating between unrelated individuals with dissimilar genotypes
Stabilizing selection
Individuals nearest the mean have the highest fitness. the mean stays the same, variation is reduced
directional selection
individuals at one extreme have the highest fitness. Mean trends toward that extreme
Disruptive selection
individuals at both extremes have higher fitness than the mean. Variation is increased, a bimodal pattern emerges
ex. Biston betularia
The breeder’s equation
R= h^2 S
R-Evolutionary response
h^2 - Heritability
S - strength of selection
the biological species concept
a species is a group of organisms that can interbreed in nature and produce viable, fertile offsprings
The Phylogenetic species concept
A species is a group of organisms that share a common ancestor and can be distinguished from other organisms by particular traits
The morphological Species Concept
A species is a group of organisms that are similar in appearance
what is a prezygotic barriers
prevent mating or prevent fertilization if mating occurs
what is a postzygotic barriers
prevent a hybrid zygote from developing into a viable, fertile adult
types of prezygotic barriers
- habitat Isolation
- temporal isolation
- behavioral isolation
- mechanical isolation
- gametic isolation
types of postzygotic barriers
- Reduced Hybrid Viability
- Reduced Hybrid Fertility
- Hybrid breakdown
microevolution
changes in allele frequencies across generations
- small-scale changes
- short time frames (human time scales)
macroevolution
accumulation of many microevolutionary changes, such that a new group arises
- large-scale changes
- long time frames
phylogenetic trees
a graphical depiction of the history of relationships among a group of organisms
speciation- creates branches, new lineages
extinction- removes branches, loss of lineages
monophyletic clads
a group that includes ALL of the taxa descended from a specific common ancestor
Paraphyletic clades
a group that excludes some of the descendants from a specific common ancestor (part of a monophyletic group)
Polyphyletic
a group that does not contain the most recent common ancestor of its members (parts of multiple monophyletic groups)
Modes of Speciation
- Allopatric (vicariance) ex. panama canal
- Allopatric (Founder Effect) ex. Oahu tree snail
- Parapatric
- Sympatric
Polyploidy
having more than 2 sets of chromosomes
Allopolyploidy
The polyploid carries the combined genomes of two separate species
Autopolyploidy
The polyploid carries the duplicated genome of a single species
Parthenogenesis
Development of an embryo in a female from an unfertilized egg (no sperm, no male)
ex. lizards that cuddle
competition
everybody loses
amensalism
one species is not affected and the other is negatively affected
rare because if none of the species are benefiting the negatively impacted
Predation Parasitism
one species is + impacted and the other is - impacted
Commensalism Facilitation
one species is + impacted and the other is not affected
ex. birch tree and douglass fir seedling
Mutualism
everybody wins
Fundamental Niches
the abiotic conditions in which a species can survive and reproduce (temperature, precipitation, soil type)
Realized Niches
The biotic conditions (interactions with other species) that determine where the species occurs
Fundamental Niches
the abiotic conditions in which a species can survive and reproduce (temperature, precipitation, soil type)
where it is physically able to occupy
Realized Niches
The biotic conditions (interactions with other species) that determine where the species occurs
where it physically occupies when competing with other species
Lotka-Volterra Model
prey -> dV/dt= rV - pVP
predator -> dP/dt = cpVP - d(predator death)P
what is competition
when individuals require the same shared limiting resource
intraspecific
competition for resources between members of the same species
ex. self thinning, less surviving but larger mass survives
interspecific
competition for resources between members of different species
ex. self thinning larger/ better competitors survive, purple plant is larger than the other plant therefore survives more
Competitive Exclusion Principle
two species competing for the same limiting resource cannot coexist. Eventually the stronger competitor will drive the weaker competitor extinct
ex. P. aurelia and P. caudatum both - impacted
coexistence
occurs when resource partitioning is applied
ex. p. bursaria and P. caudatum separates in vial, however lower carrying capacities than when grown alone
ex. different parts of a tree
resource partitioning
different parts of a tree vs. different parts of the resource (kinds of flowers different wavelength)
ex. south african bats
character displacement
species competing for the same limiting resource diverge in morphology due to natural selections
ex. galapagos finches
intermediate disturbance hypothesis
Species diversity is highest at intermediate levels of disturbance because competition reduces diversity at low levels of disturbance and death reduces diversity at high levels of disturbance
facilitation
a relationship between species where one benefits
ex. limber pine and douglas fir seedling
Obligate mutualism
a relationship that benefits both species that are reliant on the relationship for reproduction or function
ex. yucca plant and yucca moth
Facultative Mutualism
a relationship between species where both benefit but are not reliant for reproduction or function
ex. plants and mycorrhizae
Conditional Interactions
relationships that can shift from one interaction to another
ex. Mycorrhizae is always + impacted but the plant can be - impacted when it is able to acquire enough nutrients from the soil with its own roots and the mycorrhizae continues to take the sugar from the plant
low vs high elevations
at low elevations species interactions are usually competition and at high elevations the relationships turn mutualistic. they must work together to survive harsh conditions
primary succession
new land , bare rock, NO soil
takes time to develop
ex. lava (new island)
secondary succession
when an environmental catastrophe occurs and kills everything, however soil is PRESENT
*soil allows colonization of the environment faster, also some seeds depending on ecosystem can survive within the soil
pioneer species
ones that can disperse very well, can survive harsh environments, short life spans and reproduce really quickly (r-selected)
