Genetic additions to, or subtractions from, a population resulting from the movement of fertile individuals or gametes

Causes different populations to maintain similar allele frequencies

Cuban tree snail

Fruit flies - hetero @ 14% of its loci and any 2 flies typically differ by approx. 1%

Humans vary by approx. 1%

1. Mutation

2. Sexual Recombination

rare, random, often (but not always) deleterious

Deleterious mutant alleles are usually rapidly purged from a pop = lower fitness

After one generation of random mating, genotype frequency for 2 alleles will be:

p² + 2pq + q²

p=dominant, q=recessive, p+q=1

Unpredictable fluctuations in allele frequencies from one generation to the next due to chance (sampling error). It causes allele frequency to drift up and down randomly over time.

*Population size is critical variable

The smaller the pop, the larger the effect

Founder event occurs when a group leaves a population, emigrates to a new area, and starts a new population.

if small, its allele frequencies probably differ from those of the source pop=founder effect

Change in genetic diversity caused by a catastrophic plunge in population size. By chance, some alleles may be lost completely and ratios may be altered

e.g. Northern elephant seal (blubber hunting)=low genetic diversity levels therefore more vulnerable to new pathogens

mating between relatives - reduces frequency of heterozygotes and increases homozygotes in each generation

The reduction halves each succeeding generation 

Observations:

1. Individual Variation

2. Overproduction and competition

Inferences:

1. Unequal reproductive rates 

2. Evolutionary adaptation - increase in frequency of desirable traits

encompassed all life forms living and dead. one common origin for all life on this planet.

evidence so far= almost all organisms use the same 64 mRNA codons to specify the same amino acids

similarity of morphological traits (e.g. same general forelimb structure in vertebrates)

Darwin interpreted structural homologies as product of descent with modification

similarity in embryo morphology and/or pattern of tissue differentiation.

e.g. all vertebrates have gill pouches and tails early in embryonic development

similarity in the DNA sequences of genes from different species.

Produces structural and developmental homologies

(e.g. human and fly genetic sequence are 90% similar!!)

combines darwins theory, mendels theory, and mathematical pop. genetics.

genetic variation occurs spontaneously through random mutation and is constantly reshuffled via meiosis. 

Changes in frequencies of alleles from gene flow and genetic drift, and natural selection

natural selection pattern in which heterozygous individuals have higher fitness than homozygous - increases genetic diversity.

e.g. sickle cell anemia- higher hterozygous fitness in malarial areas is "balanced" by lowered fitness of homozygous recessive

Occurs when natural selection increases frequency of one allele.

reduces pop. genetic diversity over time. 

if continues long enough, favored alleles frequency reaches 100%=fixed

alleles no longer found are lost

e.g. avg body size of swallow increased, Gough island mice devloped larger bodies to eat birds, not used to terrestrial predation

occurs when individuals with intermediate traits reproduce more than others, thereby maintaining intermediate phenotypes in the pop. 

Decreases pops. genetic variation over time but doesn't change avg. trait value.

e.g. very small/large babies are more likely to die, leaving narrow distribution of birth weights

opposite of stabilizing selection; occurs when extreme phenotypes are favored.

maintains genetic variation but does not change the mean value of a trait.

e.g. only long or short beaks, very different snails from bird predation, butterflies (batesian mimicry)

enhanced ability to attract mates, leading to survival. 

directed by female choice or male-male competition. 

According to Bateman-Trivers, SS is strongest in sex that invests least in offspring (usually males)

evolution not always acquisition of new traits/more complexity, based on adapting to environment.

e.g. loss of eyes in cave animals

parasitic barnacles

anagenesis - the accumulation of heritable changes altering the characteristics of species

Cladogenesis ("branching") - process by which new species form

pre-darwinian concept. species were viewed as distinct unchanging entities, characterized by invariable distinguishing features (usually morphological)

Problems=geographical variation and sexual dimorphisms

a species is a reproductive community of populations that occupies a specific niche in nature.

problems= pops. are partially inter-fertile

pops. which are strictly asexual

wish to assess relationship to ancestral forms

the study of connections between all groups of organisms as understood by ancestor/descendant relationships.

Part of larger field of systemics, also including taxonomy

Fossil Record

Morphologies

Genomes of living organisms

genes found in all organisms andh ave been inherited from a common ancestor.

14% of amino acids all present in vertebrates

shared, derived changes among different groupings

Used to form cladograms. can be morphological or molecular

Reading phylogenetic trees

(Branches, nodes, sister taxa, ploytomy, tips)

Branches - represnet populations through time

Nodes - show where ancestral groups split into descendent groups.

sister taxa - adjacent branches (names organisms, top part)

Polytomy - node where more than two descendant groups branch off

Tips - the branch endpoints (living groups or extinctions

Universal ribonucleoprotein particles that translate the genetic code into proteins.

Typical bacterial ribosomes consist of 57 different molecules (3rRNA's and 54 proteins)

Homologous structural backbone RNA in all lifeforms

spherical, rod-shaped, Spiral.

These were the first fossils ever found

photosynthetic bacteria, produce oxygen as waste product.

changed entrie chemistry of the planet from performing photosynthesis which introduced oxygen into the atmosphere

possible that oxygen levels before late proterozoic era, were low enough to suport single-celled eukaryotes but not multicellular animals

multicellular animals cannot esist at levels below 10% but single-celled eukaryotes can survive at lower levels

multicellular algae and apperaed animal embryoes.

earliest animal evolution evidence (570-580 Ma)

dating from 565 million years ago. animals had:

1) simple radial forms

2)many body segments and legs

caused by bacterium streptococcus pyogenes

example of rapid bacteria replication when immune system fails

Antibiotics inhibit bacterial growth, however bacteria rapidly evolve resistance to our antibiotics and pose health threats (i.e. staph infection)

1) Overuse of antibiotics - antibiotics given to livestock, good chance to form resistance and spread to humans from ingestion

2) Spread of resitance genes among diverse bacteria via plasmids

independent, circular, DNA molecules that carry only a few genes and replicate autonomously.

Conjugation is the transfer of plasmids between bacteria (conjugation tube)

makes resitance easier and more widespread

not considered to be alive

infect every type of cell known

cannot perform metabolism on their own so they hijack cell's machinery to reproduce

VERY small

1) entry into host cell

2) Production of viral proteins

3) Replication of viral genome

4) assembly of new generation virus particles

5) exit from infected cell

 Lytic -  described in virus cycle (enter cell replicate and leave)

Lysogenic - virus enters host cell and integrates into genome making virus inheritable and effecting evolution

Influenza

(flu)

made up of 8  segments

spread mainly through coughing/sneezing

1) point mutation - change surface glycoprotein coat of virus, changing our immune system ability to recognize it

2) reassortment - happens when more than one virus infects a cell simultaneously, resulting daughter cells contain RNA segments from both viruses

example: HIV

large fraction of human genome compsed of previous retroviruses

Primary - occurred in plantae lineage enablin photosynthesis

Secondary - spread to 3 other eukartyotic lineages by engulfing organelles

- distribution of lifelong mesquito-repellent nets in endemic areas

- more effective drug therapy

- Vaccines

- Targeting malarial proteins of secondary endosymbiotic origin

unusual because they multiply extracellulary

cell surface typically covered by many copies of a single variable surface glycoprotein (VSG)

*elude immune system reaction (antibody production) by switching VSG's. They have thousands of variants

include all eukaryotes except green plants, fungi, and animals

Many species are photosynthetic while others obtain carbon compunds by ingesting food or parasitizing other organisms