![Page 1: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/1.jpg)
Evolution of Populations
![Page 2: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/2.jpg)
A. Genetic drift is a change in allele frequencies due to chance.
• Genetic drift causes a loss of genetic diversity.• It is most common in small populations.• A population bottleneck can lead to genetic drift.
– It occurs when an eventdrastically reducespopulation size.
– The bottleneck effect isgenetic drift that occursafter a bottleneck event.
![Page 3: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/3.jpg)
The founder effect is genetic drift that occurs after start of new population
–It occurs when a few individuals start a new population.
![Page 4: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/4.jpg)
B. Sexual selection occurs when certain traits increase mating success.
• Sexual selection occurs due to higher cost of reproduction for females.– males produce many
sperm continuously– females are more
limited in potential offspring each cycle
![Page 5: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/5.jpg)
C. Isolation can cause speciation.
1. Geographic isolation
• physical barriers divide population
![Page 6: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/6.jpg)
2. Temporal isolation
• timing of reproductive periods prevents mating
![Page 7: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/7.jpg)
3. Behavioral isolation
• includes differences in courtship or mating behaviors
Example: female fireflies only respond to light patterns of males of their own species
![Page 8: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/8.jpg)
History of Life
![Page 9: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/9.jpg)
Fossils can form in several ways. • Permineralization occurs when minerals carried
by water are deposited around a hard structure.
![Page 10: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/10.jpg)
• Trace fossils record the activity of an organism.
![Page 11: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/11.jpg)
• Amber-preserved fossils are organisms that become trapped in tree resin that hardens after the tree is buried.
![Page 12: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/12.jpg)
• Preserved remains form when an entire organism becomes encased in material such as ice.
![Page 13: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/13.jpg)
• Specific conditions are needed for fossilization.
• Only a tiny percentage of living things became fossils.
![Page 14: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/14.jpg)
PETRIFIED WOOD – These trees thrived in a sub tropical forest ecosystem 180-220 million of years ago. When they fell they were covered by volcanic ash that seeped into their cells. Over millions of
years the ash crystallized into a silica-quartz composite that gives it the “stone-like” quality.
Arizona - World’s largest collection of petrified wood
![Page 15: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/15.jpg)
• Relative dating estimates the time during which an organism lived.– It compares the placement
of fossils in layers of rock.– Scientists infer the order in
which species existed.
![Page 16: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/16.jpg)
• Radiometric dating uses decay of unstable isotopes.– Isotopes are atoms of an element that differ in their
number of neutrons.
neutrons protrons
![Page 17: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/17.jpg)
– A half-life is the amount of time it takes for half of the isotope to decay.
• Radiometric dating uses decay of unstable isotopes.
– Isotopes are atoms of an element that differ in their number of neutrons.
![Page 18: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/18.jpg)
Several sets of hypotheses propose how
life began on Earth. • There are two organic molecule hypotheses.
– Miller-Urey experiment
– meteorite hypothesis
electrodes
heat source amino acids
water
“atmosphere”
“ocean”
![Page 19: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/19.jpg)
Microbes have changed the physical and chemical composition of Earth. • The oldest known fossils are a group of marine
cyanobacteria. – prokaryotic cells– added oxygen to
atmosphere– deposited minerals
![Page 20: Evolution of Populations. A. Genetic drift is a change in allele frequencies due to chance. Genetic drift causes a loss of genetic diversity. It is most](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649e415503460f94b33951/html5/thumbnails/20.jpg)
Eukaryotic cells may have evolved through endosymbiosis.
• Endosymbiosis is a relationship in which one organism lives within the body of another.
• Mitochondria and chloroplasts may have developed through endosymbiosis.