Bio 101 Exam 3 Flashcards
(64 cards)
0
Q
Theory of Evolution by natural selection
A
-variation
-every population produces more #’s than environment can handle
-causes competition
-those that most successfully compete live, others die
-how population evolves
Darwin
1
Q
Evolution
A
- the change in phenotype in a population over time
- change in underlying genotype drives this change
- change in genotype occurs through random natural mutation of DNA
- change in phenotype occurs through natural selection
2
Q
3 possible models for evolution
A
- static
- transformation
- common descent
3
Q
Static
A
species arise separately and do not change over time
4
Q
transformation
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species arise separately but do change over time in order to adapt to the changing environment
5
Q
common descent
A
species do change over time, new species can arise, all species derive from a common ancestor
6
Q
Fossil evidence
A
- provide evidence of form
- provide context to function
- also provide geographical information
Transitional fossils: fossil that is inbetween two different species
7
Q
Homology
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•Similarities in structure between organisms that arose from a common ancestor
-embryonic homology
8
Q
Vestigial
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•Non-functional or reduce remnants remaining from evolutionary history
9
Q
Molecular evidence
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- Comparing the differences or similarities in the DNA sequences of genes that encode proteins of identical function btwn two or more organisms
- If we did not arise from a common ancestor, there is no reason to speculate that gene sequences would be similar
- Mutations arise spontaneously in genes at a given rate
* Molecular clock
10
Q
pseudogenes
A
- Animals from a common ancestor should have remnants of genes they no longer use
* Blind cave fish still have genes for making eyes
* Chickens still have genes for making teeth
* Humans still have vitellogenin gene used for making yolk
11
Q
Endogenous retrovirus (ERV) evidence
A
- Some retroviruses can insert their viral DNA into the genome of the host organism
- If the viral DNA is inserted into germ cell DNA, the viral DNA will be inherited by the offspring
12
Q
Natural selection requirements
A
- variation in traits in a population
- environment cannot sustain unlimited growth
- some traits provide better reproductive fitness than others (these are the ones that are perpetuated)
- heritability of traits
13
Q
Examples of natural selection
A
- peppered moths have variation in pigmentation, and prior to industrial revolution, dark colored moths were rarely observed in nature. It was mostly the speckled ones
- in humans, change favors lower BMR because individuals with higher BMR die before reproducing
14
Q
Antibiotic resistance
A
- bacteria can evolve genes that make them resistant to antibiotics
- widespread exposure to antibiotics causes non-resistant bacteria to die
- resistant bacteria continue to multiply and increase in total proportion of population
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Q
Allele frequency
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- frequencies of alleles within a population are not always equal
- set of any possible alleles for an organism within a population is known as the gene pool
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Q
Fixation
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-eventually only one allele, other allele(s) no longer there
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Q
Genetic drift
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- Variation in allele frequency among small populations that occurs purely by chance
- in a SMALL population
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Q
Migration
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-input of alleles into one population from another
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Q
Founders effect
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-founders to to new place, isolated from old population, so new population is going to differ from the old
20
Q
Genetic bottleneck
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-catastrophic event, wipes out/ changes a population’s allele frequency
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Q
Patterns of selection
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- different conditions may cause selection to have differing effects on a population
- directional selection
- disruptive selection
- stabilizing selection
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Q
Directional selection
A
-shift in direction
Ex) height range. Avg is 5’10 if all the tall people die, the height range shifts direction and the avg is now 5’8
23
Q
Disruptive selection
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-trait in the middle dies off, no middle ground
Ex) tan mouse dies off, only black and white survive
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Stabilizing selection
-only one trait survives
| Ex) white and black die off, only brown left
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How do new genes arise?
- DNA is subjected to spontaneous mutations
- despite the cell having extensive repair mechanisms, mutations still get transmitted to offspring
- humans have about 170 mutations per generation
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Gene duplication
- most common way new genes arise involves gene duplication
- genes that carry out essential functions cannot endure mutations that disrupt that function
- duplicated genes can tolerate mutations since original copy is present to perform intended function
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Radiocarbon dating
Has to do with Decay of carbon 14
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Convergent evolution
Process by which organisms that are not closely related to one another independently evolve similar traits due to similar environmental circumstances
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Linnaean Classification System
* Domain – Eukarya, Prokarya, or Archea
* Kingdom – Animalia, Plantae, Fungi, Protista
* Phylum – Ranking based largely on body plan (Chordata)
* Class – Based on more general similarities (Mammalia)
* Order – Even more general similarities (Primate)
* Family – Minor differences between members (Hominidae)
* Genus – Very closely related members
* Species – Members that are ummm…
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Species
- traditionally defined as organisms that could interbreed to produce fertile offspring
- however: doesn't allow for things like bacteria that don't reproduce sexually
- currently no universal definition
- commonly considered a group of organisms to which change in allele frequencies for all their genes are confined (gene pool)
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Gene flow
- spread of an allele through a species gene pool
- in sexually reproducing species, occurs through meiosis and fusion of gametes
- in asexually reproducing organisms occurs most often through mitosis
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Speciation
-happens because gene pool becomes isolated
(Given common descent, how does one species become another)
-gene pools must become isolated
-mutation and selection must occur to isolated populations independently
-reproductive isolation must occur
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Types of speciation
- allopatric speciation
- chromosomal reproductive isolation
- sympatric speciation
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Allopatric Speciation
- 2 populations become reproductively isolated by a PHYSICAL barrier
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Chromosomal Reproductive Isolation
-genomes of two organisms are too different to align during meiosis
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Sympatric speciation
-populations are reproductively isolated by behavioral or temporal barriers NOT physical barriers
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H. Erectus
- 1st hominid to have modern body proportion
- left Africa and colonized Asia
- made stone tools and used fire
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H. Heidelbergensis
- migrated to Europe
- developed shorter, stockier proportions to conserve heat
- 1st species known to bury dead, cared for sick and elderly
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H. Neanderthalensis
- likely specialized from reproductively isolated european population of h. Heidelbergensis
- gave offerings to dead and wore symbolic jewelry
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H. Sapiens
- likely speciated from African population of h. Heidelbergensus that was reproductively isolated
- May have interbred with h. Neanderthalis
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Human genetic diversity
-sampling of SNPs from two humans shows differences in approx 1 per 1000 bases
•Greatest variation in African genomes consistent with theory of origination
•Indels also affect genetic diversity
•The majority of human genetic diversity is evolutionarily neutral
•Some SNPs and indels cause phenotypic changes
•Skin pigment
•Lactose tolerance
•Disease resistance
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Biodiversity
- variety within all living organisms
- ~1.6 mil diff species identified
- ~10 mil total species (bcuz many aren't identified)
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Domains
- broadest classification of life
- eukarya
- prokarya or bacteria
- archaea
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Eukarya
-organisms with a membrane bound nucleus
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Prokarya or bacteria
Lack of membrane bound nucleus. membrane contains peptidoglycan
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Archaea
- lack membrane bound nucleus and lack peptidoglycan in membrane. Complex RNA pol similar to eukaryotes
- live in extreme environments that would kill of anything else
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Phylogenetic tree of life
-Look at slide
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Endosymbiosis
How mitochondria came into existence
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Eukaryotic kingdoms
- Protista
- fungi
- plants
- animals
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Protista
```
1.5 billion years
Take in or make food
Most one celled, but not all
Only kingdom not grouped by lineage
Has members similar to members in the other three eukaryotic kingdom
```
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Fungi
1.5 billion years
Generally resemble plants
But at the cellular, genetic, and biochemical levels resemble animals
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Plants
700 million years
450 million years ago appeared on land
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Animals
600 million years
400 million years ago appeared on land
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Chordates
Has a spine
| 500 million years
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Viruses
•Not accepted as “living” because they cannot maintain homeostasis and cannot reproduce or grow without a host
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Permian extinction
•~95 % of life on Earth went extinct at the end of the Permian era
* Volcanic eruptions emitted CO2 into atmosphere
* Coal burning from volcanoes emitted more CO2
* Warming thawed frozen methane releasing it into atmosphere
* Oceans became anoxic due to warming
* All life on Earth today is descended from the 5% that survived
* It took ~30 million years for life to recover
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Triassic-Jurrasic Extinction
* More than half of all life on Earth went extinct
* Allowed dinosaurs to become dominant life on Earth
* Thought to be caused by massive volcanic eruptions
* Possible asteroid impact
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Cretaceous-tertiary extinction
* ~75% of all life on Earth went extinct
* Caused by combination of volcanic eruptions, asteroid impact, and changing ocean currents
* Allowed mammals to become dominant form of life on planet
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Sixth entinction?
* Since 1850, the extinction rate of mammals and birds has increased 100 fold
* Up to 140,000 species may be going extinct per year
* Currently 29% of amphibians; 21% of mammals; 12% of birds; and 3% of plants are in danger of extinction
* Causes of extinction are all man-made
* Habitat destruction
* Pollution
* Invasive species introduction
* Exploitation
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How does an ancestral prokaryote become an ancestral eukaryote?
- An invagination of the plasma membrane resulted in the formation of the nucleus and endoplasmic reticulum
- the cells later engulfed endosymbiotic heterotrophs and autotrophs to give rise to mitochondria and chloroplasts, respectively
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Major theme in plant and animal evolution
Adapt to life outside of water
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Mass extinction
Abnormally large number of species die off in a geologically short amount of time
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Major events of animal evolution based on developmental body plan formation
- multicellularity
- formation of germ layers
- development of tube-within-a-tube body plan
- formation of coelom
- development of either a mouth or anus from the blastopore
