Exam 1 Flashcards
Evolution
Change in population’s genetic structure throughout time
Natural Selection
reproduction of the fittest/best adapted individuals, causes evolution through unequal reproductive success
adaptation
trait that increases fitness of individual
Evolutionary Fitness
- contribution of individual to next generation, relative to contribution of others
- individuals can have adaptations, populations evolve
Darwin
- Published in 1859
- Darwin & Wallace independently concluded the same thing
Directional selection
- natural selection favoring a shift towards more extreme phenotypes to adapt to conditions
- Darwin’s finches-measured thickness of finch beaks. Thick beaks would survive and flourish in dry seasons to open hard shelled nuts, thick beaks lived
Diversifying selection
- selective pressure against intermediate phenotype. For fur, darker or lighter fur, not inbetween color
- If it keeps up, and groups separate and not interbreed, speciation would occur
Stabilizing selection
- Selective pressure against extreme phenotypes
- example: human birthweight: big babies are healthy until they’re too big
Natural selection
Natural selection that results in reproductive success directly rather than indirectly. More offspring means that the traits will be favored in future generations
Intersexual selection
Intersexual selection happens between both sexes, it’s a selection that favors reproductive output that favors sexual dimorphism (difference in appearance between sexes)
mate choice-female chooses mate based on mating rituals/appearance
Intrasexual selection
Intrasexual selection happs between single sex. Characteristics that favor competition between same sex. Example: male seals fight and compete for beach turf
Genetic Drift
- how evolution can occur
- random change exaggerated in small population
- bottleneck effect
- founder effect
- Gene flow
- Mutation
bottleneck effect
The chance that survivors with a certain phenotype of a catastrophic population decrease will repopulate and spread that phenotype
fixed alleles-only 1 allele is left (for a given trait)
founder effect
a few individuals from a population start a new population with a different allele frequency than the original population
Ex. red and yellow ladybugs on island A, red bugs hop on island B and repopulate
Gene flow
sample of other genes gets carried into a new group and offspring are made with new traits
increase gene flow, increase similarity between populations
decrease in gene flow means decrease in similarity
no gene flow means speciation occurs
Mutation
Changes in DNA that create new alleles (versions of genes)
Ultimate source of genetic diversity in populations
Beneficial mutations that are actually adaptations sprout through population by natural selection
Evidence for evolution
Direct observation
Fossil Record
Biogeography
Comparative anatomy
Anatomic homologies
-indicative of evolution from a common ancestor
homologous structures
built the same way due to common ancestry differ in function, show evidence of evolution, adapt to different needs
Ex. tetrapods: 4 footed
analogous structures
look similar because of similar selection pressure, not common ancestry. Adapt to similar needs
Rudimentary
vestigial
evolutionary left overs, non adaptive or useless structures
Comparative embryology
Evolutionary-development
evolution of development one cell to an adult
Conserved molecular characters
DNA, RNA, proteins
Specific enzymes, e.g. RuBisCo
Turns carbon into sugar in all photosynthetic organisms
specific enzyme pathways, e.g. glycolysis
DARWINIAN EVOLUTION: The Modern Synthesis
- helping us use population genetics and evolutionary theory to see how population generation changes
- combines field of population genetics with theory of natural selection
Theoretical non-evolving population populations in Hardy Weinberg
Very large population size (no genetic drift)
No gene flow (no migration)
no mutations
Random mating (no mate choice)
No selection, all individuals are equal in reproductive success
Hardy Weinberg
The point is that sexual reproduction alone (recombining genes) won’t cause evolution in order for the allele frequencies to change, other factors must influence the population
Phenotype
outward appearance of a trait (i.e. purple flowers)
genotype
alleles present for a trait
AA Homozygous dominant
Aa heterozygous dominant
aa Homozygous recessive
Hardy Weinberg Equilibrium
genotype frequencies
p2+2pq+q2=1
p2-homozygous dominant frequency AA% genotype
2pq-heterozygous frequency Aa% genotype
q2-homozygous recessive frequency aa% genotype
p+q=1
p=frequency of dominant allele in population’s gene pool A
q=% of alleles that are “a” recessive
Allele Frequencies
p+q=1
p=frequency of dominant allele in population’s gene pool
q=% of alleles that are “a” recessive
SPECIES
-Species include at least 1 or more populations of organisms with the potential to interbreed with one another but NOT with members of other species
Morphological species
based on anatomy/appearance
biological species
based on ability to interbreed, concept is based on infertility rather than physical similarity
Prezygotic barriers
(Before zygote is formed)
mechanical isolation-ex. black sage pollen structures are different thatn white sage
Genetic isolation
incompatible gamete structures will deny genetic proteins
Postzygotic isolation
- Hybrid inviability, hybrid sterility, hybrid breakdown
- hybrid breakdown-1st generation of hybrids do fine, subsequent hybrid gens don’t do well
- hybrid inviability-hybrids just die
- hybrid sterility
WHAT LEADS TO A NEW SPECIES?
Genetic isolation and genetic divergence
Allopatric speciation
Sympatric diversifying selection
Polyploidy
Sympatric diversifying selection
could eventually lead to 2 separate species
ecological isolation
division of resources
Polyploidy
having extra sets of chromosomes
involves error in meiosis
auto polyploidy-self fertilization
alloplooidy-hybridization and self fertilization
Types of natural selection
Directional selection
Diversifying selection
Stabilizing selection
Types of sexual selection
Intersexual selection
Intrasexual selection
Natural selection
Comparative anatomy
- Anatomic homologies
- Rudimentary
what keeps species separate
- Prezygotic barriers
- Genetic isolation
- Postzygotic isolation
WHAT LEADS TO A NEW SPECIES?
Genetic isolation and genetic divergence
Allopatric speciation
Sympatric diversifying selection
Polyploidy-having extra sets of chromosomes
PLANT EVOLUTION
Nonvascular plants –> seedles vascular ferns –> gymnosperms –>Angiosperms
Nonvascular plants
- vascular system of plant is used for transport of water and nutrients
- plants rely on water for reproduction
seedles vascular ferns-large, tree sized
reproduce with spores, rely on water for reproduction, swimming sperm
gymnosperms-conifers and needle plants
1st seed plants, but they still have spores like all other plants. Deeds are better at dispersal and are free from water for reproduction. Pollen carries sperm in the air
Angiosperms-flowering plants
Dominant. Includes flowers and fruits, they are faster reproducers
EUDICOTS
- 2 cotelydons in seeds (usually part of an embryo)
- Usually 4-5 floral parts
- usually a netlike array of leaf veins
- basically 3 pores of furrows in pollen grain
- vascular bundles arranged as a ring in stem
- palm trees, corn, grasses, orchids, lillies, and tulips are eudicots
MONOCOTS
- multiples of 3 petals
- in seeds, only 1 cotyledon
TISSUE SYSTEMS IN PLANTS
(all run continually through plant)
dermal
ground tissue
vascular
dermal plant tissue
protection, water loss prevention
ground plant tissue
middle layer, bulk/meat of plant. Food storage, supports the plant, protects the plant
vascular plant tissue
located most internally in plant, moves nutriends, water
ROOTS
anchor in soil absorb water and nutrients conduct water and nutrients to shoot storage monocots & eudicots stolon roots
storage in roots
carb chain of glucose molecules, easy to break down
monocot roots
have fibrous roots
eudicot roots
have trap roots
stolon roots
horizontal stems that allow plants to reproduce asexually
cuticle on leaf
made of wax, lipid, hydrophobic
xylem
transports water and minerals up plant, is dead at maturity. It leaves cell walls behind
phloem
transports sugars both up and down plant, alive at maturity
collenchyma cells in leaf
flexible, elastic, stringy, and provide support in body parts and growing areas
Stopped at GROUND
stopped at GROUND
