BIOL 102 Flashcards
What did Darwin and Wallace hypothesize?
Species evolve due to changes in a population from one generation to the next (shared ancestry)
How to measure survival of the fittest?
number of mates, number of offspring, number of grandchildren
What are adaptations
anatomical, physiological, or behavioral traits that are inheritable, increase an individuals survival/reproduction to its environment, is functional, variations of population, and increases fittness
Natural selection
process by which certain inherited traits make it easier for some individuals to survive/reproduction by changing the genetic makeup of population overtime.
Evolution
genetic makeup of a population that changes overtime, sometimes resulting in the adaptations to new environments
Homologous traits
traits similar across species because their common ancestor passed down those traits to its descendants
transitional features
are intermediate traits that are present in extinct species
pedigrees
track inheritance of a trait across generations and make predicitons
carrier
an individual who has one copy of the allele but is not expressed phenotypically
express the trait
shown phenotypically
recessive or dominant in pedigree?
recessive often skip a generation
Chiasmata is…
formed between homologous chromosomes
autosomal
neither male of female; only 1 pair of sex chromosomes
X-linked inheritance?
only effects the X in males and females
co-dominant
Fully expressed in different parts (patches of black, patches of white on a cow) use all capital letters (3 phenotypes)
incomplete dominance
red, white create pink (3 phenotypes)
Y-linked ?
biological males have only 1 Y chromosome- 1 allele; males only pass down their Y-linked traits to their songs
Mutations….
introduce permanent changes to an individual’s genetic material
deleterious mutation
harmful
neutral mutations
dont really know they are there
advantageous mutation
helps one survive and reproduce
Hardy-weinberg equilibrium means no what?
no evolution is occuring
5 assumptions of HW E?
- no natural selection
- no migration
- no genetic drift
- no mutations
- random mating
- large populations
gene pool?
double the amount of alleles (150—-300)
allele frequencies
f(a)=
f(A)=
p+q=1
genotype frequencies
p2+2pq+q2=1
p2
frequency of AA
q2
frequency of aa
2pq
frequency of Aa
fixed allele
not equal to 1 or 100%
particulate inheritance
hereditary determinants (genes) of a trait maintain their integrity from parents to their offspring
Alleles
an individual has 2 particles of a trait, one inherited by each mom and dad
genotype
combination of alleles (AA, Aa, aa)
phenotype
physical characteristics shown
homozygous
AA or aa
heterozygous
Aa
hetero x homo dominant
Aa x AA
hetero x homo recessive
Aa x aa
alleles segregate
a parent passes down one allele to an offspring at random (50/50)
genes assort independently
traits are often inherited independently from other traits
do both parents contribute equally to the genotype of their offspring?
yes
vestigial traits are common
such a wisdom teeth
Clarifications about evolution via natural selection
- populations evolve and adapt overtime
- small differences from one generation to the next accumulate as more time passes
- natural selection is not random
- natural selection is not goal-driven and does not result in perfection
- species that have more traits in common are more likely to be related to one other than to other species
- we look for transitional features present in extinct species
Mendel was interested in?
how traits are passed down from parents to offspring
what were mendel’s hypotheses
- blending inheritance- offspring are perfect mix of their two biological parents
- acquired characteristics- are passed down
conclusions of mendel-
- genes passed down from parent to offspring
- both parents contribute equally to the genotype offspring
- some alleles are dominant in expression to others
what did mendel observe?
see color/shape
pod color/shape
plant height
flower shape/color
did mendel hypotheses work?
no they didnt
what book did darwin write
on the origin of species
what did darwin book do
species showed evident from “descent with modification” from common ancestors; natural selection is a mechanism behind descent with modification
darwin saw what
how individuals were suited for environment are more likely to survive and reproduce
what is directional selection?
one survives better than the other
expected:
AA= 0.25
Aa=0.50
aa= 0.25
observed:
AA- 0.35
Aa- 0.45
aa- 0.10
change was in the homo dominant better survival
Stabilizing selection (best of natural selection)
Expected:
AA-0.25
Aa- 0.50
aa-0.25
observed:
AA-0.20
Aa-0.65—– better survival with the heterozygous
aa-0.15
low variation in population average phenotype
the average might not change
disruptive selection
acts against the average phenotype, high variations
expected:
AA- 0.25
AB-0.50
BB- 0.25
observed:
AA- 0.35 increase
AB- 0.30 lower
BB- 0.35 increase
recombination is the mixing of alleles
Fb; fB
somatic mutations
cell in body; cant be passed on (cancer)
germ-line mutations
cells and plants; can be passed on to offspring
alleles…
different forms of genes and different genetic sequence
genotypes
genetic makeup of a gene
phenotype
display the physical characteristics and can be influenced by genotypes and environment
Artificial selection
the identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations
