Evolution Flashcards
State the people (in order) who were evolved in developing the theory of evolution
- Jean Baptiste Lamarck (1744-1829)
- Thomas Malthus (1766-1834)
- Charles Lyell (1797 -1875)
- Charles Darwin
- Niles Eldredge and Stephen Jay Gould
What is Lamarckism
Lamarckism is the theory developed by Jean Baptiste Lamarck, concerning adaptations of species.
- he argued that individuals adapt during their lifetimes, and pass on those adapted traits to their offspring (who started where their parents left off)
- Individuals would increase an ability by using it more often (effectively making the organ stronger and larger), whereas they would lose certain abilities by disusing them (making the organ smaller until it disappeared)
EXAMPLE: giraffes with short necks stretched their necks so often to reach the higher leaves that their necks grew. They then passed on the long necks to their offspring
DISPROVEN: evolution takes a long time, individuals can not drastically adapt during their own lifetime; nor can they pass on capabilities
Who was Thomas Malthus? What was his theory? How did this theory impact Darwin’s theory of evolution?
Thomas Malthus was a British scholar, influential in political economy and demography, as well as a professor. He published many works called “an essay on the principle of population.”
He theorized that population growth would always surpass food growth (we can not produce food at the same rate at which our population is growing). He theorized that unless there was a massive war or some outbreak, there would be a mass starvation.
His theory helped Darwin develop the theory of evolution. If there were no constraints on a population (such as disease, predation, etc.- general selective pressure) there would still be a limited amount of food, ensuring that natural selection would still operate. He concluded that natural selection is in effect all the time.
Who is Charles Lyell? What is his theory and how did it influence Darwin?
Charles Lyell was a lawyer and a professor of geology.
He published the book ‘Principles of Geology’, in which he advocated for the idea that the earth was shaped by slow moving forces, still in effect today, over a very long period of time. This led him to believe that the earth is much older than previously thought (contradicting the churches belief).
Lyell was close to Darwin, and was very influential in his life. Darwin read his book aboard the Beagle on his expedition, and was very inspired. The idea that the earth was very old gave enough of a time line to evolutionary processes to happen.
Charles Darwin
(1809- 1882) .
Darwin was born into a wealthy family, his grandfather was in influential scholar in England. He married his cousin. Initially planned on studying medicine, later switched to divinity at Cambridge.
In 1831 he went on a five year scientific exhibition aboard the SM Beagle. On that trip he read Charles Lyells book called ‘The Principles of Geology’, which initially inspired his theory of evolution. While studying the Galapago islands, he gathered evidence about the variety of finches (see other card)
Darwin came back from his exhibition and spent the next 20 years working on his theory and writing his manuscript. After hearing that another naturalist, ALFRED WALLACE had come up with a similar theory and was going to publish it, Darwin finally decided to publish his manuscript, The Origin of Species
Why was Darwins theory so controversial?
- contradicted the churches beliefs about how the earth and animals were created
- a single line in the book indicated that humans too, may have evolved (made everyone mad because it insinuated that humans are animals)
Niles Eldredge and Stephen Jay Gould
- in 1972, they proposed a theory called the ‘punctured equilibrium’ , built on Meyers theory of geographic speciation
- Punctured Equilibrium is a theory that directly contradicts Darwins theory of gradualism
- it insinuates that most of the time, species are in a stable state (not evolvnig).
- Due to some environmental factors there is a rapid burst of change (speciation) and then stability for a long time
-Gradualism is more of a continuous change, insinuating that species are all the time, constantly evolving
Why is Lamarckism disproven
- although one can aquire many characteristics during its life, many features do not change according to use (your eyesight does not improve the more you use your eyes)
- Individual changes for certain characterstics may happen, but they do not alter your DNA
Although Jean Baptiste Lamarck’s theory was flawed, what crucial (and correct) points did he make?
- species evolve over time
- A species evolves in response to it’s environment, and becomes more adapted to it
- changes are passed down from generation to generation
What are the mechanisms for evolution
- natural selection
- sexual selection
- artificial selection
- genetic variation
- genetic drift
- mutations
What is evidence for evolution
- paleontology (fossil records)
- microbiology/physiology (universal biochemical organization)
- anatomy (homologues vs analogous)
- early embryonic development
what is evolution
- process of biological change over time
- based on relationships between species and their environments (environmental pressures etc)
- central idea of biological evolution is that we all stem from a common ancestor
- evolution is responsible for the amount of diversity we have on earth
DECENT WITH MODIFICATION
-evolution only occurs when their is a change in genetic material in a species over a period of time (genetic differences are heritable)
KEYPOINT- long term change (ie. evolution) happens due to genetic inheritance
decent with modification
how Darwin defined evolution
- an evolutionary mechanism
- change in genetic material over a period of time
Darwins Finches
On his exhibition aboard the SM Beagle, Darwin spent a large portion of time in the Galapagos Islands where he saw all the variety of finches (finches later became his main example of evolution)
- all of the finches appeared to have a common ancestor on the mainland, yet each island had a finch with a specific adaptation catered to the type of food on the island
- the most distinguishable adaptations are the beaks
- Large strong beaks = nuts
- narrow thin beaks = insects
- parrot like = fruit
****** 13 species evolved from one finch - original species had a medium sized beak for feeding on medium sized seeds 1. leaves (pointy triangle) 2. insects (long thin point) 3. tool using (thicker stronger) 4. grubs/worm things (short) 5. fruit (parrot like, strong thick)
What is natural selection
- **mechanism for evolution
- process by which, individuals that are better adapted to their environments are more likely to survive and reproduce
Elements of natural selection
- there is variation in characteristics
- individual members of a species vary in physical characteristics
- ^so that variations can be passed down from generation to generation
EXAMPLE. Some beetles are green, others are brown - Survival of the fittest
- who can reproduce the best/most
- environments cant support unlimited growth, therefore only some individuals will reproduce to their full potential (those who are fertile, best at surviving etc)
EXAMPLE. green beetles survive better because they blend in with leaves, and are able to then reproduce - Competition
- members of species compete for limited resources
- some are better at getting resources than others - Adaptation
- natural selection forces populations to become better adapted to their environment
- each generation will be better adapted than the last
**Natural selection does not anticipate change, it is situational (environment changes —–> selection takes place)
**Really the only requirement for natural selection is that the individual must be able to survive and reproduce
What is the key to natural selection?
reproductive success
Peppered moths
EXAMPLE OF NATURAL SELECTION
- before the 1800s, tree bark was relatively light, therefore the moths were lighter in colour
- after the industrial revolution, waste darkened the trees, killing off the lichen
- light moths could not adapt to the change, so darker moths became more abundant due to selective pressure from birds
Artificial selection
- **mechanism for evolution
- occurs when humans exert environmental pressures, as opposed to the environment doing it naturally
- done to isolate a specific trait
- Selective breeding and artificial selection are a type of biotechnology
- humans bred wolves that were more docile, eventually turning them into dogs
Genetic Variation
- **mechanism for evolution
- variations occur in a species as a result of the variety of combinations of alleles
- sexual reproduction results in higher genetic diversity and variance
Mutations
- **mechanism for evolution
- the source of new alleles, is mutations
- mutations are generally harmful or neutral
DELETION
DUPLICATION
INVERSION
TRANSLOCATION
Gene flow/migration
- ***mechanism for evolution
- parts of a population migrate, effectively making the gene pool smaller or larger
ie. a group of finches leave the mainland to go to an island; the alleles of future genrations are limited to the allels of the original group that came to the island
ie. A town has a population of brown bunnies. If a white bunny comes to town, there are now more alleles
Genetic drift - bottle neck vs founder
**mechanism for evolution
Genetic drift occurs when there is suddenly a smaller population
BOTTLENECK: severe natural disastor, surviving organisms survive by chance. Allele pool is smaller, consists of only survivng organisms. (pure chnce)
FOUNDER: small group leave original population, go to start new population (results in a smaller allele frequencey). example, galapagos finchesd
ADAPTAIONS TABLE
animals - coping with abiotic factors, obtaining food
plants - coping with abiotic factors, obtaining food
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animals coping with abiotic factors
- heavy fur, hibernation, flying south
obtaining food
- quick moving tongues, longer necks, long snouts
plants coping with abiotic factors
- deciduous habitat, bulbs, cold hardiness
obtaining food
- root hairs, larger leaves
Fossils. What are they? How are they formed
***evidence for evolution
fossils are hard impressions in solid rock (thin filaments such as leaves, or entire organisms stuck in amber, footprints, bones etc)
Formation:
- bodies usually decompose. But if they are in a situation where there is a lack of oxygen (ie. buried by sediments, stuck in amber) decomposition is prevented.
- layers of sediment over the organism increase pressure over time, body becomes compressed, and very gradually chemical changes occur that result in the body being mineralized
