Mutation and Genetic Drift
Mutation: random change in the genetic code
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
Genetic Drift: random change in gene frequency from one generation to another
most populations either
fix the alleles
gene frequency of 1
lose the alleles
gene frequency of 0
Selection
Differential Reproduction
means
Given phenotype is giving more or less offsprings as other penotypes
Response to Selection
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
Natural Selection:
Environment is selecting
Stabilizing selection
Intermediates have an advantage
Disruptive selection
Directional selection
The mean shifts to either side
Artificial Selection:
breeder (an individual) is selecting
Sexual Selection
Males compete, females choose
Extinction
Getting rid of diversity
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
The fewer the population, the more vulnerable it goes to extinction
Human Evolution
Australopithecus afarensis
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
The brain size
increased dramatically
Strong selection for brain size
Intelligence is an adaptation
as a result of
Natural Selection
is heritable
Diversification of Language
parallels with the human evolutionaly process
like new species, it arose in isolation accumulating more and more differences over time
Population Regulation
Biotic Potential
Increase population size
rate of reproduction
ability to withstand adverse conditions
defense mechanisms
Environmental Resistance
Decrease population size
insufficient nutrients, food, or water
diseases
predation
competition
insufficient living space
adverse weather conditions
Density Independent Regulator
emigration
Biological Control Techniques of agricultural pests
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
FOOD
Primary regulator of human population
Epidemics
Black Plague in 1348
killed almost all in England
Global Warming
Greenhouse Effect
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
Tropical Diseases with Global Warming
Malaria
Schistosomiasis
Filariasis
Dengue
Biological Impacts
Altitudinal/poleward shift in species ranges
Earlier Spring events
Coral bleaching
warming and acidification
Species Extinctions
tropical frogs
Phenology
Phenological change: change in the timing of life cycle event
such as plants and flowering time