Evolution (copy)

evolution

change in allele frequencies over time in a species or a population

these changes come from mutations typically and affect how these species adapt to the non static environment

Lamarck

these changes come from mutations typically and affect how these species adapt to the non static environment

What was Lamarck right about?

was right abt use and disuse

giraffe necks grew due to it being __used__

and the human appendix shrunk due to __disuse__

What was Lamarck wrong about?

falsely held the idea that acquired characteristics are inherited (while this is sometimes true it is mostly wrong)

Who is Darwin?

\-traveled around the world and theorized natural selection.

\-Published Origin of Species book

three takeaways from darwins’s book

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1. Resources are limited.
2. Organisms compete for survival.
3. There is variation among individuals in a population.

How was Darwin’s thinking impacted by his voyage?

he gathered evidence and made observations that led to his theory of evolution

saw many different species and evonirments and how those organisms lived

this led to him writing a book

What was Darwin’s theory?

his theory is that evolution occurs because of natural selection

Darwin’s book and why it took him so long to publish it

His first book was *On the Origin of Species* and it was published in 1859

it took him so long due to the fear of the reaction to this theory of evolution and how it went against the church

he also put it off to gather more evidence for his theory

8 characteristics of his book

1. Populations have enormous __reproductive__ potential.
2. Population sizes tend to remain relatively __stable__.
3. Resources are __limited__.
4. Organisms __compete__ for survival.
5. There is __variation__ among individuals in a population.
6. Much variation is __heritable__.
7. __Fit__ individuals are able to produce more offspring that survive longer.
8. __Evolution__ occurs as advantageous traits accumulate over time.

5 main pieces of evidence for evolution

homologous/analogous structures, biogeography paleontology, molecular biology, and embryology

homologous structures

structures found in different organisms that all evolved from a common ancestor

over time the structures developed

ex. upper limb bones of human, bat, dog, and whale

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starts from one ancestor; ends up in various

analogous structures

structures in various species that are similar but they evolved from very different ancestors

ex. penguin and porpoise

opposite of homologous

vestigial

remnants of once useful traits that have shruken due to disuse

ex. appendix

paleontology

the study of fossils that are usually found in sedimentary rocks

isotope dating

is a technique that is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed

compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay

2 main types → carbon isotopes vs uranium isotopes

Carbon isotope dating

measuring age of fossil by how much carbon is left;

In C-14;

if starting with 10 grams; it would take 1 half-life (5730) years to decrease by half.

IF MORE THAN 23K YEARS OLD: Uranium isoptope

half life

the time taken for the __radioactivity__ of a specified __isotope__ to fall to half its original value.

uranium isotopes

(like U-238) has a half-life of 4.5 billion years

fossil types

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molecular biology

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comparisons of DNA/RNA/amino acids sequences in various species indicates how closely (or distantly) related they are to each other

ex. comparing __hemoglobin__ amino acid sequences in various vertebrates

ex. comparing __cytochrome-c__ (a protein found in mitochondria and chloroplasts) in species

ex. comparing gene sequences

DNA percentage similarities for these:

embryology

the study of embryos and their development

vertebrates share a surprising number of similarities when they are embryos

stages of development happen in the same sequence in vertebrates (timing and size in each stage varies)

many vestigial structures in some species

vestigial

leftovers from ancestors (highly reduced in size/functionality)

Common structures in vertebrate embryos:

limb buds

gill folds

tail

yolk sac (doesnt actually contain yolk in us because of the umbilical cord)

adaption

the process of adapting to something (such as environmental conditions)

divergent evolution

various species arising from one common ancestor over time

ex.

A = ancestral bird, B = hummingbird, C = ostrich

A = ancestral fish, B = dogfish, C = hammerhead shark

A = ancestral desert plant, B = saguaro cactus, C = organ pipe cactus

convergent evolution

two species becoming more like in morphology over time

ex.

A = ancestral amphibian, B = ancestral reptile, C = salamander, D = gecko

A = ancestral marsupial, B = ancestral placental mammal, C = sugar glider, D = flying squirrel 

coevolution

a symbiotic relationship that causes two species’ evolutions to affect each other over time

Examples → Bees/flowering plants, predator/prey relationships, parasite/host

sexual selection

the phenomenon in which varying traits are present in males vs. females in many animals species (corresponding to something that indicates “increased fitness’) - it comes down to what’s more/less attractive in potential mates

Examples →  lion’s manes in males, peacock feathers, horns or antlers in many mammals, birds (dances, feather displays, songs)

adaptation

a heritable trait that helps an organism take advantage of its surroundings

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better adapted individuals = individuals with more/better traits

natural selection

process by which organisms that are more fit, or adapted, to its environment survive to produce offspring

organisms “selected” to live on

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Over production +variation => natural selection + inheritance

Normal distribution

ex. human height

no pressure at all

(unlike stabilizing no pressure that causes a certain height to considered perfect.)

Stabilizing distribution

both extremes have less survival vs middle; just right

ex. plant height; too short = not enough sun; too tall= susceptible to breaking easily

Directional distribution

(can shift to either end of spectrum)

less survival in one extreme vs the other

ex. Beak sizes

Disruptive distribution

ex. lightest and darkest furred organisms are preferred in an ares with dark and white sand

artificial selection

humans manipulating breeding of plants, animals, etc. for our own wants/needs

Ex. = domesticated dogs, cats, livestock, silkworms

Ex. = agriculture (every fruit/veggie you’ve ever eaten)

heterozygote advantage

the case where heterozygous individuals have “the best of both worlds” in a sense - providing the opportunity for offspring to inherit different traits (and keep in mind, the phenotypes that are most fit can change over time due to environmental change or circumstances changing!)

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ex. sickle cell anemia (recessive=affected with lack of nutrients; hetero= immune to malaria and have normal blood for functionality: dominant= not immune at al; normal

ex. can have a chance of passing on a beneficial trait that is recessive.

adaptive radiation

numerous species **radiating** from a single ancestor over a long period of time and spreading out across a lot of different regions

Ex. → Darwin’s Galapagos finches

Ex. → The Silversword Alliance (plants) of Hawai’i

gene flow

immigration and emigrations of individuals in/out of a population

genetic drift

when the allele frequencies of a population change, not due to natural selection, but due to genetic probabilities

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ex. blue birds become more common for no reason; population with 1/2 black and white rabbits, but most black rabbits die in an accident not due to their trait which causes the probability of white rabbits to increase.

bottleneck

huge reduction in number of individuals of a population/species; resulting reduced population will begin to evolve quickly to survive and regenerate.

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founder effect

individuals arrive at a new territory or recently formed landmass → their genes set the stage; initiate it all

Hardy-Weinberg theorem/equilibrium

**The formulas:**

**p + q = 1**

**p^2 + 2pq + q^2 = 1**

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p = frequency of the dominant allele (ex. = 0.3 would be 30%)

q = frequency of the recessive allele (ex. = 0.7 would be 70%)

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p^2 = frequency of homozygous dominant individuals

2pq = frequency of the heterozygous individuals

q^2 = frequency of the homozygous recessive individuals

5 requirements for Hardy-Weinberg theorem

1. No natural selection
2. No mutations
3. No sexual selection (random mating)
4. No immigration/emigration (no gene flow)
5. No small populations 

reproductive isolation

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences; can cause speciation

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ex. two populations of birds begin to separate as each begin to have a diff preference of dance patterns.

how reproductive isolation leads to new species

if a part of a species is isolated from the other than the isolated part can reproduce and evolve without any input from the other part resulting in new **allele frequencies** (evolution) over time which eventually result in a new species

speciation

the formation of new species due to reproductive isolation

Prezygotic isolation (type of reproductive isolation)

Habitat isolation

Temporal isolation

Behavioral isolation

Mechanical isolation

Gametic isolation

Postzygotic isolation (type of reproductive isolation)

Reduced hybrid viability

Reduced hybrid fertility

Hybrid breakdown

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Divergent Evolution

Convergent evolution

Coevolution