BIO Test LAP 10

evolution

3 types of natural selection on polygenic traits

Directional Selection, Stabilizing Selection, Disruptive Selection

Directional Selection

* an extreme phenotype is favored
* Causes allele frequency to shift over time in that direction
* Ex. Peppered Moths
* One phenotype is favored

Stabilizing Selection

* Eliminates the extremes of a phenotype.
* Ex. birth weight in humans - if your baby is too small (not able to survive and thrive) and if your baby is too big (might kill the mom and themselves)
* When the middle phenotype is favored

Disruptive Selection

* Favors the extremes and eliminates the middle phenotype.
* **Can lead to speciation**
* **Can become a new species**
* Ex. Rabbits that live in an environment with black and white rocks
* Grey is a disadvantage.
* When 2 distinct phenotypes, this can lead to a new species forming

Genetic drift

* Random
* When an allele becomes more or less common in a population due to chance
* BY CHANCE
* 2 types:
* Bottleneck Effect and The Founder Effect

Bottleneck Effect

* An externa event (natural disaster) kills off many in the population.
* The new population has different allele frequencies than previously.
* By chance

The Founder Effect

* Random what alleles go to a new place, cause by population starting a new population.
* A few individuals colonize a new habitat.
* Can cause major changes in allele frequencies.

Species

Speciation

* how new species form
* Occurs when gene flow between 2 groups stops
* Known as Reproductive Isolation
* 3 types: Behavioral Isolation, Geographic Isolation, Temporal Isolation

Behavioral Isolation

* Reproductive Isolation #1
* If 2 populations develop different courtship rituals or behaviors, they will stop interacting/mating with each other.
* If I turn left when I dance and you turn right, we don’t match (as birds)
* WE BECOME DIFFERENT SPECIES

Geographic Isolation

* Reproductive Isolation #2
* 2 populations are separated geographically.
* Mountains, rivers, bodies of water
* When something geographical, like a natural barrier separates species causing them to adapt.

Temporal Isolation

* Reproductive Isolation #3
* When populations reproduce at different times, they will eventually diverge into separate species
* Ex. Orchids in the rain forest pollinate at different times, resulting in diverse species.
* Separating by time

Fossil Record

* show us about what date the rock is from
* Relative and radioactive dating

Relative Dating

* Generic method of dating fossils using layers
* Lower layers = older fossils
* Index Fossils - give scientists an approximate date for other things

Radiometric dating

* Absolute dating
* More precise than relative dating
* Relies on radioactive isotopes which break down at a steady rate.
* Half - Life = time required for half of the radioactive atoms to decay
* Carbon - 14

Major events in Earth’s history

* 540 mya - Snowball Earth
* 250 mya - Pangea Forms
* 65 mya - meteor hits Earth

Geological Changes/factors

* Plate Tectonics - created mountains, volcanoes, etc. changing the environment
* Comets/Meteors - destroying ecosystems and killing a lot of animals, letting the animals with the best adaptations survive and thrive.
* Climate Change - makes it too hot or too cold in places for animals to live, either they must adapt or die.

Biological Changes/Factors

* Life on Earth also changed in response to living organisms changing.
* Ex. Photosynthesis is allowed for carbon dioxide levels to drop and oxygen levels to thrive.
* Allowing for more to thrive.
* Things moving from water to land.

Mass extinctions may occur…

Main theory for the extinction of dinosaurs

* May occur during an Ice Age (snowball Earth), Meteor strike, Upset ocean current (Pangea forming)
* When the meteor hit Earth since the dinosaurs were big, meat eaters, etc. they died off leaving the smaller reptiles to thrive.

Macroevolution

* evolution of entire groups of organisms
* Big scale organisms
* Big changes in time
* Ex. Flowering plants evolved 130 mya
* Ex. Dinosaurs appeared 250 mya and existed until 67 mya

Evolutionary Rates

* fossil evidence shows that evolution can occur at different rates and at different times.

Gradualism

* Slow, steady, change over time.
* Ex. Horses

Equilibrium

* stable periods interrupted by rapid change of species.
* Usually seen in mass extinctions.

Adaptive Radiation

* A single species diverges into multiple different species.
* Ex. Darwin’s Finches

Convergent Evolution

* unrelated organisms evolve similar traits due to similar niches - analogous structures
* Ex. Penguins and dolphins have similar body types.

Contributions of Miller and Urey

* Early atmospheric conditions + lightning can form organic compounds.
* Showed life can be made with right chemical components.

Pasteur’s experiment

* Proved that ***spontaneous generation*** did not occur.
* Theory at the time that said life could be created from nothing.
* Boiled liquid in a sterile flask
* Bacteria only able to grow when it was exposed to air.
* Life did not generate on its own.

Taxonomy

* science of classifying and naming organisms
* **Binomial Nomenclature** - Developed by Linnaeus
* “genus species”
* Scientific 2-part naming system

Taxon

group

Binomial Nomenclature

* - developed by Linnaeus
* “genus species”
* Scientific 2-part naming system
* Important because it is easy to communicate.

Hierarchical classification system

Kingdom

Phylum

Class

Order

Family

Genus

Species

* not just based on looks → now Genetics, development/embryology, cell biology

3 domains of life

Bacteria, Archae, Eukarya

Bacteria

* Kingdom Eubacteria
* bacteria in this
* No nucleus - Prokaryotic Cells

Archae

* Kingdom Archaebacteria
* Bacteria that live in extreme environments
* No nucleus - Prokaryotic Cells

Eukarya

* Kingdom Protista
* Kingdom Plantae
* Kingdom Fungi
* Kingdom Animalia
* Only group that has a nucleus

Endosymbiotic Theory

* 2 unicellular organisms joined together in symbiosis to form the first eukaryote

4 Kingdoms

* Kingdom Protista
* Kingdom Planta
* Kingdom Fungi
* Kingdom Animalia

Kingdom Protista

* “grab bag Kingdom” - contains things that don’t fit elsewhere.
* Generally unicellular
* Unicellular organisms that are not bacteria
* Ex. Algae, Amoebas

Kingdom Planta

* Autotrophic - go through photosynthesis.
* Multicellular and have cell walls.
* Eukaryotic
* Ex. Trees, Ferns, Grass

Kingdom Fungi

* Heterotopic
* Multicellular and have cell walls
* Eukaryotic
* Ex. Mushrooms, Mold, Yeast

Kingdom Animalia

* Multicellular
* Eukaryotic
* Heterotrophs

phylogeny

* Study that reconstructs the evolutionary history of a species
* When you reconstruct the evolutionary history of a species
* Adds time into your classification
* Throws in time that the animal diverged

Cladogram

* Shows evolutionary relationships
* “family trees”
* Timeline showing who is related to who

Derived characterisitcs

* trait that arose in the most recent common ancestor
* Everything after has the trait
* Ex. seat belts on cars

Clade

* Group of similar organisms on a cladogram

Outgroup

* most distant organism, not in the larger clade

Major characteristics of a virus

* NOT ALIVE
* only composed of DNA and Protein
* Not made of cells \*\*
* Can only reproduce by infecting living cells
* 2 types of infections

Lytic Infection

* Quick cycle of infections
* Virus injects DNA into cell → Viral copies created → cell bursts → Viruses Escape
* Ex. Ebola, COVID - 19, Rhonavirus (common cold), Influenza

Lysogenic Infection

* Longer cycle due to period of **dormancy**
* Virus injects DNA into cell → Viral DNA incorporates with host cell DNA → the cell copies itself many times (this is dormancy period)
* Then:
* Cell enters Lytic cycle → Viruses created → Cell Bursts → Viruses Escape
* Ex. HIV, Herpes, Chickenpox