biol 1307 exam 3

microevolution

change in allele frequency in a population over generations

conditions for microevolution

genetic variation and selection

types of selection

1. random

2. natural

3. sexual

sources of genetic variation

1. mutation

2. sexual reproduction (crossing over, independent assortment, fertilization)

locus

the specific position of a gene on a chromosome

gene pool

allele frequencies in a population

hardy-weinberg principle

expected frequency of genotypes in a population for a single locus with only TWO alleles if evolution is NOT occuring

genetic drift

• random selection

• allele frequency changes without regard to whether traits provide a reproductive advantage

• causes: sudden environmental change

types of genetic drift

1. founder effect

2. bottleneck

gene flow

individuals was a geographically distinct population brings new alleles into the local population

disruptive selection

intermediate phenotype is selected against

directional selection

more extreme phenotype is favored

stabilizing selection

intermediate phenotype is favored

difference between genetic drift and natural selection

genetic drift is random and survivng alleles dont necessarily provide reproductive advantage

calculating genotypes using HW

1. p² x # of individuals

2. 2pq x # of individuals

3. q² x # of individuals

then compare theoretical and actual population to determine is population is at equilibrium

sister taxa

sharing a most recent common ancestor

shared ancestral characters

originated in the ancestor

shared derived characters

characters different from ancestor and unique to the clade

clade

complete group of descendants from a single ancestor

parsimony

tree with the fewest evolutionary changes is most likely

traits to compare

1. morphology

2. biochemistry

3. pattern of embryonic development

4. dna sequence data

homologies

characters shared because they were inherited from a common ancestor BUT function may have changed during evolution

homoplasy

characters with similar function but NOT due to gradual modification of an ancestral structure (due to selection pressure). do NOT share a recent common ancestor

convergent evolution

homoplasies (similar adaptations) evolve due to similar selection pressure, not inheritance (ex: bird and insect wings)

vascular seed plants shared derived traits

• vascular system

• seeds

• pollen and ovules

prokaryotic diversity

1. genetic variation

2. metabolic diversity

3. ecological roles

similarities between bacteria and archea

• can aqcuire new genes thru lateral gene transfer

ways ATP can be produced by prokaryotes

• converting light energy

• oxidizing organic molec. (sugars, hydrocarbons)

• oxidizing inorganic mlc (NH3, H2S)

protista

all major eukaryotes

3 multicellular eukaryote groups

Kingdom Fungi, Animalia, and Plantae

evidence for endosymbiont theory

1. replication, transcription, and translation are similar in archaea and eukarya

2. chromosomes and translation system similar in proteobacteria and mitochondria

3. mitochondria and chloroplasts have charas. of bacteria (double membrane, circular dna, small ribosomes, binary fission)

evolution of multicellular eukaryotes

plants and fungi → first animals (insects) → tetrapod on land

characteristics shared between land plants and green algae

• chlorophyll a and b

• spores

land plants derived shared characters

• cuticle

• pores for gas exchange

nonvascular plants

• no internal support system

• swimming sperm

• gametophyte is most obvious stage

vascular plants have

system of vessels transporting fluids (xylem and phloem)

• sporophyte is most obv stage

xylem and phloem

xylem- water, ions, nutrients

phloem- sugars

shared derived charas for vascular seed plants

• spores → microscopic gametophytes within specialized structure on sporophytes (ovules or pollen)

angiosperms

• vascular seed plant

• flowers, seeds, fruit

porifera

• first multicellular animal

• cells not organized into tissues

• 2 layers of cells held together by collagen

cnidaria and bilateria shared trait

gastrulation and formation of tissues

bilateria traits

1. bilateral symmetry

2. protozomes (1st embryonic opening is mouth)

3. deuterstomes (mouth is second opening)

ecdysozoa

descend from protozomes

ecdysis- shedding of exoskeleton to grow larger

anthropoda

1. exoskeleton and jointed legs

2. 6 legs

descend from lophotrocozoa

lophotrocozoa

1. spiral cleavage pattern of embryonic cells

2. hox genes and genes for cell resp

deuterostomes

1. 2nd embryonic opening is mouth

chordata

descend from deuts

• embryos have notochord; dorsal gollow nerve cord; pharyngeal gill slits; muscular; muscular post-anal tail

niche

range of conditions a species can tolerate and resources it can use

factors affecting distributiona nd abundance

1. abiotic

2. biotic

3. geology

dispersion

spatial dist of indivs

density

#of indivs/area

types of dispersion

1. clumped

2. uniform

3. random

cause of clumped dispersion

habitat is suitable in patches

cause of uniform dispersion

competition for a resource

cause for random dispersion

resources are evenly dist in the habitat

qudarat

count all orgs in a fixed area

transect

count all orgs along a sampling path of a fixed area

mark-recapture

tag idivs repeatedly and recapture

population growth formula in exponential growth

B-D

population growth formula in limited

rn(K-N)/K

K-N=0

pop size is at K

K-N>0

below K

K-N<0

exceeded K → negative growth rate

density indep regulation

• as pop density increase, birth and death rate remain constant

• physical factors affect same proportion of population regardless of pop density

density dependent regulation

• as population density increases, br decreases and/or dr increases

density dependent regulation reasoning

• competition for space

• if breeding territory is necessary, some wont reproduce (br down as density up)

• higher predation at higher density (dr up as density up)