Mutation and Genetic Drift

occurs

every 1 in 10,000 to 1 in 100,000 gametes

at different loci at different rates

Age-dependent

As you get older, mutation rate increases

About 95% of all mutations are harmful

which are

Homozygous mutations

most populations either

fix the alleles

gene frequency of 1

lose the alleles

gene frequency of 0

means

Given phenotype is giving more or less offsprings as other penotypes

means

Changes in the mean from one generation to another

which depends on both

Heritability

it is a proportion of the phynotypic vatiation that is genetically based

Selection Differential

it measures the intensity or strength of selection

Stabilizing selection

Intermediates have an advantage

Disruptive selection

Directional selection

The mean shifts to either side

Males compete, females choose

Mass Extinction

65 million years ago, nearly all dinosaurs went extinct

Factors of Mass Extinction

Asteroid Hits

can be traced by rock signature

such as Iridium

Consequences of asteroid hit

Into Orbit

the explosion launches into orbit at 50 times the speed of sound

Choked sky

little sunlight penetrates to the ground for several months

Killer waves

Tsunamis as high as 300 feet

Terrible tremor

million times greater than the strongest tremor recorded in human history

Volcanic Activity

Genera longevity is longer than species longevity

Major causes of contemporary extinction

Diseases

Species Introduction

Hunting

Habitat Destruction

is the common ancestor of other Australopithecus species

Homo habilis

lived between 2.5 - 1.5 million years ago

this species was a toolmaker

Homo erectus

spread out of Africa to Europe and Asia

Neanderthal men

lived between 150,000 - 30,000 years ago

Modern humans

evolved about 50,000 - 35,000 years ago

increased dramatically

Strong selection for brain size

Intelligence is an adaptation

as a result of

Natural Selection

is heritable

parallels with the human evolutionaly process

like new species, it arose in isolation accumulating more and more differences over time

Increase population size

rate of reproduction

ability to withstand adverse conditions

defense mechanisms

Decrease population size

insufficient nutrients, food, or water

diseases

predation

competition

insufficient living space

adverse weather conditions

Density Independent Regulator

emigration

by parasites, predators, or pathogens

prickly pear cacti regulated by cactoblastis

by reproductive control

release of sterile male insects

by hormones

pheromone traps to control insect pests

Primary regulator of human population

Black Plague in 1348

killed almost all in England

reduction of heat lost into atmosphere due to greenhouse gases

which are CO2, methane, and nitrous oxide

leads to warmer global temperatures

Physical environmental changes

change in precipitation

rising sea levels

melting Arctic ice and glaciers

warming oceans

more intense hurricanes

Malaria

Schistosomiasis

Filariasis

Dengue

Altitudinal/poleward shift in species ranges

Earlier Spring events

Coral bleaching

warming and acidification

Species Extinctions

tropical frogs

Phenological change: change in the timing of life cycle event

such as plants and flowering time