BIO311D

Life Cycles

G1 - S (DNA Replication) - G2 - Mitosis - Meiosis

Meiosis

Produces gametes

Meiosis I:
Prophase I
Metaphase I
Anaphase I
Telophase I

Chromosome disjunction during
Anaphase I

Meiosis II:
Prophase II
Metaphase II
Anaphase II
Telophase II

Chromatid Disjunciton during
Anaphase II

Mistakes

Meiotic Nondisjunction
(in Anaphase I or II?)

produces deficient (ex. monosomic)
or duplicate (ex. trisomic) gametes

Polyploidy

Mutations and
Genetic Drift

Mutation:
Random changes in genetic code,
Thus ULTIMATE source of
genetic variation

Evolution arises from advantageous mutations
being selected for (individuals with that mutation
reproduce more offspring, continuing trait)

Hardy Weinberg Equilibrium:
p^2 + 2pq + q^2 = 1
(When GENOTYPIC frequency
stays the same from generation
to generation)

For HWE to exist, must be:

-Need random mating
-No mutations
-Large population size
-No migration
-No selection

For evolution to occur
there must be:

-Nonrandom mating
-Small population size
-Mutations must occur
-Migration
-Sexual selection

sexual selection is ALWAYS phenotypic

p & q are allelelic frequencies

Fixed: allele goes to 1
Lost: allele goes to 0

Most populations either fix or lose an allele by CHANCE, this results in a genetic drift over time.

Genetic Drift:
random changes in gene frequency from
one generation to another due to
SAMPLING ERROR

sampling error= chance variation from the expected value. With a larger population size, there is less of a chance of sampling error.

Issues with sampling error:

Bottleneck Effect

After a catastrophe where populations are greatly reduced in size, more prone to extinction bc LOSS OF HETEROZYGOSITY. Could lose an allele which would reduce the amount of genetic variation.

Founder Effect

(*Within the same generation) New "colonizing" population's gene frequencies not likely to be the same as original population due to sampling error.

Adaptive Radiation

Form of
Divergent Evolution?

Is a result of natural selection

Character
Displacement

selection working in opposite directions. There is compeition at the mean so phenotypes diverge in order to reduce competition. ex) Galapagos Finches Beak Size: separately they are similar, over time beak size diverged to reduce competition in eating the same food.**also: Competitive Exclusion

Adaptive Differentiation

development of different PHENOTYPES from a common ancestor due to adaptations to different environments

Human Evolution

Shared common ancestor with
Apes ~6.5 mya

Ardipithecus
(Bipedal)
over 5 mya

Bipedalism was more beneficial seeing as the African Rift Valley was changing from a tropical to a savannah landscape. Standing upright allowed our ancestors to see above the tall grasses, reach food on trees, cool more efficiently from the sun, and most notably: conserve more energy (as this was more energy efficient than walking long distances on four legs).

Australopithecus
over 4mya

Extinctions caused by ENVIRONMENTAL CHANGES.

A. Afarensis (Lucy)
common ancestor

A. ganhi

Homo habilis
2-1.8mya

First signs of greater encephalization:
(more intelligent beings
had more offspring- thus, larger brains
continued to be passed down)

Homo erectus
1.8mya-350,000
moved out of Africa to
Middle East, Asia...

(Archaic) Homo sapiens
evolved 350,000
years ago

H. sapiens neandertals
(goes to Europe and Middle East)

FoxP2 gene found in neandertal DNA led scientists to believe neandertals could has possibly had a language.

DIES OUT

Possible causes of extinction:-Not advanced enough technology to catch food in order to sustain and maintain food requirements for large bodies.-Lived in cold climates-H. sapiens sapiens were better adapted to enviornment, started out competeing neandertals, leading to their demise.

H. sapiens sapiens
(move from Africa and
Middle East)

H. sapiens sapiens have ~3% neandertal DNA in us.Outlived neandertals due to taller slimmer bodies which require less energy to sustain, more advanced hunting tools (such as throwing spears) allowed them to get food without putting themselves in harm's way.

Traveled to Asia and Australia
60,000 years ago

Traveled to
New World
25,000 years ago

Later reached
South Americas

North America:
extinction of many animals 14,000-6,000
years ago bc hunted to extinction

Presence of humans increases the probability of extinction for animals in the area. Major BIODIVERSITY effect!

Why so little genetic variation today?
Theorized bottleneck effect. All mankind
today derived from ~600 breeding individuals

Reached South Pacific
Islands moving from SE Asia

islands that are much closer geographically have residents that are closer related genetically as well, when compared to islands that are further apart

No major extinctions in Africa
(people were already residing there
from the beginning, thus there was
no major change)

Adaptations such as
endurance running, sweating,
and less body hair were seen here.

lead to "Persistence Hunting"
(needed bigger meaty foods
to support larger bodies and
brains).

Later developed into
present day apes

Global Warming

Green-house Gasses

retardation of heat escaping the atmosphere by certain "greenhouse gases"

CO2 Levels Increasing
(in atmosphere)

CO2 "Sinks"
-photosynthetic plants
-oceans

Positive correlation to
temperature RISE

Methane Gas Increase
(in atmosphere)

Nitrous Oxide

CFCs

Ozone Depletion
(Concentration thinning)

greatest depletion of ozone over SOUTH POLE (ANTARTICA)

allows UV light to more easily penetrate Earth's surface

have seen in increase in skin cancer

In coming years:

Temperature INCREASE

Causing:

Physical Environment Changes:
-warmer ocean temperatures (releases methane gas)
-Higher sea levels (due to glacier melting)
-more intense hurricanes
-change in percipitation

Biological Changes:
-Lattitudinal/poleward shift in species ranges
-earlier spring events/later fall events
-coral bleaching
-species extinctions

ex) Maple tree ranges moving North
Beech tree ranges moving north
Euphydaas editha (butterfly) moving north
along west coast

Most Negatively Effected:
-cold adapted organisms
-severely range restricted species

Pollution

Nuclear Radiation

Nuclear Winter

Causes:
-Temperature decrease
-Darker
-photosynthesis decrease
-productivity decrease (worldwide)

Acid Rain

H2SO4
Sulfuric Acicd

HNO3
Nitric Acid