Anthro 101 Exam 1 Section 2
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Alfred Russell Wallace
- Independently derived the same ideas about evolution as Charles Darwin
- fieldwork in Southeast Asia when he came up with the same idea
- both Wallace and Darwins papers were read at same time
Came up with the theory of evolution by natural selection:
- English Naturalist
- Published “the origin of species” in 1859
- Traveled on HMS Beagle (a research ship) in 1831 to explore the globe
- He collected data from plants and animals along his voyage
- Collected data in Galapagos islands; local finches
- noticed that domesticated animals bred for desirable traits (Humans in this case are the selective agents of animal domestication via artificial selection)
Those individual organisms who are best suited in an environment will survive and reproduce most successfully.
believed that inheritance is a blending process in which parental characteristics become mixed together and passed to the offspring
What were Darwin's 5 observations of natural selection?
(produce, stable, limited, vary, heritable)
- 1.) All populations can produce lots of offspring
- Crown of thorns starfish spawning
- Spawn 2 million eggs
- Reproductive potential exceeds # of offspring that survive – Starfish produce lots of eggs, but larger lifeforms produce less
- 2.) Population size remains generally stable
- savannah baboons – groups tend to relatively stable in their local habitat bc its in equilibrium with its landscape
- 3.) Plants and animals limited by resources
- Competition between members of same species (conspecifics)
- 2 leopards fighting
- 4.) Individuals in any population vary
- Giraffes: short necked and long necked giraffes
- 5.) Much variation is heritable
- you Get it from parents at birth
- you don’t get any genetic material after
- your genes only get passed when you reproduce
What were darwins 3 inferences?
(fit, differential, favorable)
- 1. Some organisms are more fit than others (survival of the fittest which means those best adapted are more likely to live on and pass their genes to the next generation than those that are less adapted.
- 2. Which in turn, Leads to differential survival and reproductive success(meaning not all of them will make it only the most fit
- 3. Overtime, favorable characteristics accumulate in populations
What did Darwin notice about the process of domestication that helped contribute to his formulation of the theory of Natural Selection?
He noticed that domesticated animals bred for desirable traits
What kinds of things struck Darwin as interesting when he visited the Galapagos Islands?
- He noticed geographic variation with the same species of finches
- Each island had the same range of animals, but all slightly different according to the environment and their subsistence strategy
- there were local modifications of the same species
Which famous theoretician went on a voyage on the HMS Beagle? What is the HMS Beagle?
- Charles Darwin
- A research expedition ship
Who came up with the theory "evolution by natural selection?"
What is artificial selection? Why is it done? Who came up with it?
- intentional breeding of plants and animals done to produce desirable traits
- Charles Darwin
______ does not equal success!
______ equals success!
What is the “unit of selection” and what is it that evolves in the biological world?
- unit of selection = individual
- population evolves in the biological world
describe three examples of Natural Selection “in action” that were discussed in class (one is also discussed in your text).
- Biston Betularia (peppered moth)
- Mus Musculus (mice in missouri)
- Darwins Finches
Biston Betularia example of evolution by natural selection
- the peppered moth
- preindustrial revolution there were white and black mottled moths that lived on the white lichen on trees
- the white moth on white lichen caused this species to be more dominant over the black moths
- then, pollution during the industrial revolution killed the white lichen in trees leaving the white mottled moths now more exposed to selective agents such as birds.
- This caused the darker moths to be adaptive by blending in with their environment, which led to them being the more dominant population
- at the end of the 19th century there was a shift and then the white lichen began to restore on the trees making the white lichen the dominant population again
what are some types of selective agents
- environment/weather change
Between natural selection and artificial selection the environment is more likely to be the selective agent of _______?
_____ are the selective agents for moths, because they apply selective pressure on them.
_____ are the selective agents for dog breeding
What does conspecific mean?
organisms belonging to the same species.
What did Darwin mean by fitness?
- reproductive success
- when an organism is able to pass its genes on to the next generation
what is Sexual Selection?
Why are secondary sexual characteristics referred to as an “evolutionary tradeoff?”
- type of natural selection that operates on one sex usually the male
- ex. male - male competition. gives makes physical traits to up their advantage
- Males: lots of energy invested in big body size, but Costly calories wise
Secondary sex characteristic (peacock) = more flamboyant the feathers the more attractive to mates, but also attractive to predators
- forces in the environment that influence different reproductive success in individuals
- ex. geographic isolation from rivers or natural barriers causes the formation of new species as they begin to adapt to their new environments.
- phenotypic differences between males and females of the same species
- ex. humans: females have wider hip bones than males, males have larger bone structure
generation to generation change
creation of new species over long period of time
Significance of Mice in Missouri
town of sackville Biology students knew Farmer McCroskey’s granary was filled with mice
- experimented with the pop of mice
- mice kept in check with cats
In April the population was: more dark fur than light fur mice bc mice typically active at night and so dark fur is surviving the predation
students moved cats from the equation and found out…more light fur than dark
- Then, let cats back in and almost all mice were dark again
- Predation pressure = selective agent (predation, social & environmental) Predation pressure: cats
Significance of Darwins Finches
Does not have anything to do with Darwins research, just that it was carried out in the Galapagos islands where Darwin did research
Galapagos had major drought in Island of daphne major
Hurricane Wiped out small, soft seeds
Then, Finches: had to switch to eat larger, harder seeds…smaller beaks had a hard time opening these up and spent energy here and could not invest energy in reproduction.
Hence, selection for larger beaks!
After drought, numbers stabalized again
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