Unit 1 Flashcards
Darwin & Wallace Idea
organisms share common ancestries. adaptations lead to diversity in life
Views before 1800
species = constant
variation not important; just imperfection
William Paley
The watch maker design argument. Adaptations are on purpose. species constant
Lamarck
1744-1829 1st to believe evolution occurs inheritance of acquired characteristics use/ disuse drives evolution spontaneous generation a drive for perfection
Extinction
Georges Cuvier (1769-1832)
-Catastrophism
founded the study of paleontology
established extinction as a fact: caused by localized catastrophes
Cuvier & Ibises
saw no evidence of change over time; believed in functional integration; function determines form- similarities due to common functions- not connected
Hutton
FATHER OF GEOLOGY (1726-1797)
Gradualism and an old earth
- planted idea of gradual change over long periods of time based on ancient maps and modern coastlines
Charles Lyell
expanded button’s idea of gradual change over periods of time
uniformitarianism
uniformitarianism
geological processes are so uniform that their rates & effects must balance through time
Gradualism
gradual change over long periods of time
Charles Darwin
life long naturalist
trained in medicine and for the clergy
interested in variation & biogeography
studied finches and saw VARIATION
Darwin’s basic argument
- variation- observable, but under appreciated
- heritable variation
- struggle to exist
- differential survival
- change in population’s characteristics
decent with modification
unity of life
diversity of life
match between organisms and their environment
Order of the Theories
Linnaus-taxonomy hutton-gradualism lamarck-evolution malthus-populations cuvier- paleontology Lyell- uniformitarianism darwin mendel-inheritance wallace
Evidence for Evolution
- homology
- fossil record
- vestigial structures
- biogeography
- Biochemical
- Direct observation or strong inference of evolutionary change
homology
structures with different uses but strikingly similar features–suggests “tinkering”
ex. shared developmental patterns
fossil record
simpler organisms first, then more complex
biogeography
study of distribution of organisms
Natural Selection
- variation
- heritable variation
- struggle
- differential
reproduction
5.changes in heritable characteristic of the population- evolution
Darwinian Fitness
capacity to pass on genes to reproducing offspring Depends on: survival to RD age mating success fecundity survival to RD age by offspring
fecundity
number of offspring
evolution
changes in allele frequencies in a population over time
mechanisms of evolution
natural selection
mutation
migration
genetic drift
natural selection
traits are selected for within a population can be: directional stabilizing disruptive density dependent sexual
gene
discrete unit of DNA on chromosomes
allele
alternative versions of a gene
locus
the location of the gene on the chromosome
diploid
individuals have two copies of each chromosome
called homologous pairs
can have two different alleles
sister chromatids
2 DNA molecules attached together
meiosis
halving the number of chromosomes when forming gametes (1n)
chiasma
site of crossing over
mechanisms for diversity of gametes
- segregation
- independent assortment
- crossing over
- random fertilization
law of segregation
alleles segregate into different gametes at meiosis= variation from parent to offspring
law of independent assortment
for genes on different chromosomes, alleles will segregate independently=all combinations are possible
character
heritable features of organism that can vary
trait
each variant for a character
genotype
the genetic makeup of the organism BB;Bb;bb
phenotype
the discernible features of an organism
incomplete dominance
blending of the phenotypes
centromere
connecting point of chromatids
penetrance
frequency expressed
polydactyly
complete dominance
extra finger
achondroplasia
complete dominance
Huntington’s Disease
autosmal dominant
chromosome 4
cystic fibrosis
autosomal recessive
Tay-Sachs
chromosome 15
autosomal recessive
lack of enzyme= brain degeneration
Blood types
multiple alleles:
A,B codominant
O is recessive
pleiotrophy
one gene may affect many traits e.g. HGP finding coloration and crossed eyes in siamese cats marfan syndrom sickle cell
epistasis
gene at one locus alters phenotype of gene at another locus
e.g
coat color in mice
Dog coat colors: brown is recessive, yellow is recessive and epistatic
polygenic inheritance
one trait is affected by many genes e.g skin color, height
variation between gene and pheno
the environment
epigenetic inheritance
the transmission of non-DNA sequence information through either meiosis or mitosis
genomic imprinting
parent of origin specific allele silencing, or relative silencing one parental allele compared with the other parental allele. due to methylation
linkage
tendency of genes on the same chromosome to end up together in the same gamete
x-linked recessive genetic disorders
color blindness
Duchenne Muscular Dystrophy
Hemophilia
more common in males because they only inherit one x chromosome
Ichythosis
x-linked recessive
severely scaly extremities
menkes
cells can’t absorb copper
silent
code for same amino acid
missense
code for wrong amino acid
monosomy
missing one chromosome
trisomy
one extra chromosome
nondisjuction
members of a pair of homologous chromosomes do not move apart properly during meiosis one OR sister chromosomes fail to separate during Meiosis II
Nondisjuction disorders
down syndrome, turner syndrome, klinefelter
gene pool
all the individual alleles in a population for a given locus
HWE Conditions
- large populations
- no mutations
- random mating
- isolated from other populations
- all individuals survive & reproduce equally
3 reasons to NOT have sex
inefficient
costly
risky for survival
protandrous
male 1st
protogynous
female 1st
sexual dimorphism
differences in characteristics between males and females of a species
intersexual selection
traumatic insemination
infanticide
sperm competition
combat
3 types of intersexual variation
handicap
parasite
developmental stability
Darwinian view of disease
history matters
evolving pathogens
evolution of virulence
Evolution of Virulence
virulent diseases will eventually evolve towards reduced severity
Pathogens must:
reproduce
disperse to new hosts
