What is a cheetah?
Applies to all living species including humans
A cheetah is a mammal characterized by few evolutionary traits that distinguishes it from other feline species. The species is the result of 3500 myr of evolution where more than 99% of its characteristics have evolved in species that are now extinct and less than 1% of its features are unique. Thus the cheetah is mainly the result of the history of its ancestors than its own history.
What are the types of scientific reasoning, and what are they?
- Inductive Reasoning is linked to a descriptive-based approach which is to make a generalization based on numerous specific observations. Making a broader reason, particular to general. Ie. you make an assumption (generalization) from what you saw(observation)
- Deductive Reasoning is linked to a hypothesis-based approach which involves stating a hypothesis to draw conclusions after experimenting or observing hypothesis. Making a specific reason, general to particular.
What is an if-then statement?
A prediction.
What is an assumption?
A hypothesis
How is the scientific process conducted?
- Observation
- Hypothesis
- Predictions
- Tests
5a. If hypothesis is refuted then a new a hypothesis must be made
5b. If the hypothesis is not refuted additional tests must be made to ensure that the hypothesis is not refuted
What is the scientific process?
The contract between science and knowledge.
What are the four clauses of the scientific process
- Initial skepticism on facts
- Realism
- Rationality: Logic and Parsimony
- Methodological Materialism
What is skepticism?
Asking honest questions on facts and hypothesis. Always retesting what has been found.
What is realism?
The world is older and exists independently from my perception of it where the realm of ideas doesn’t have the priority over the real world.
What is rationality?
Logic: demonstrations from a scientist must be the result of
coherent steps.
Parsimony: methodological principle which states that acceptable theories are hypothetically the most economical in assumptions.
What is methodological materialism?
All that is experimentally accessible in the real world is material or has a material origin.
How does Darwin comprehend the resemblance of species & what does it lead him towards?
Darwin comprehended resemblance of species through phylogenetic trees that species show resemblance to each other because they share a common ancestor not a common environment. Darwin’s phylogenetic terres confirmed what he knew through observation but not yet the mechanism of evolution. Darwin rejects Lamarck’s evolutionary mechanism of environmental determinism. Darwin rejects the fixity (no change) of species and accepts the concept of descent with modifications (evolution). Darwin also begins to have a very materialistic view of life that is in contradiction to the religious dogma of the time. This leads him to begin the search for an evolutionary mechanism.
What did Darwin observe in the finches of the Galápagos Islands?
The finches show morphological similarities because they share a COMMON ANCESTOR which clarifies their link to South America.
What are fossils helpful towards?
Fossils fill in the important gap in morphology. Fossils explain morphological variability/differences and the evolution of morphology. Since most of the evolutionary branches finish in extinction where 99% of species are extinct and 1% of species are living which is why fossils help us corroborate.
(All share common ancestor: Rock hyrax, African elephant, dugong)
What book did Darwin read in 1838?
Darwin read “An Essay on The Principle of Population” written by Thomas R. Malthus. Thomas R. Malthus wrote that every human population has a tendency to increase geometrically (exponentially) whereas the available resources to feed these populations increase arithmetically (linear). Where the human population increases faster than its capacity to feed itself leading to a crisis point (of chaos, famine sickness, war). During that period the individual population will want to secure itself where there will be a winner/loser situation where the losers will have no food, unable to reproduce, and die. Eventually the population will collapse to a substantial reduction in size. This reading became one of the main sources to inspire him to formulate his famous theory on natural selection.
What does Thomas R. Malthus’ principle of population graph look like?
The human population is increasing concave up and intersects with the linear growing resources where the human population goes through a turning point increasing concave down then decreases concave down to then hit the linear growing resources where the situation returns back to normal.
What are Darwin’s observations?
- Darwin’s first observation: All species can produce more offspring than their environment can sustain and many of these offspring fail to survive and reproduce. Ex. Mushroom puffball reproduces a spore cloud which contains billions of spores, maple trees reproduce samaras, and the mola mola- ocean sunfish will produce over 300 million eggs
- Darwin’s second observation: Members of a population often vary in their inherited traits. (Dots from the Asian ladybird beetle and the shell colour of amphidromus adamsii are genetic traits)
What is natural selection? What are its inferences?
Natural selection enables the emergence of adaptations. They infer that:
- Individuals whose inherited traits gives them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals
- In generational shifts there is an unequal capacity of survive and reproduce called a differential reproductive success which results in an accumulation of favourable traits in a population essentially greater proportion and frequency will increased of a certain phenotype/genotype limiting genetic variability
What are important notions linked with natural selection?
1.Individuals do not evolve only populations evolve
(Individuals are only carriers of gene) (Lamarckism: individual ≠Darwin: population)
2. Only hereditary traits are subjects to natural selection
3. Genetic variability is needed for evolution to occur
4. Natural selection corresponds to differential reproductive success within a population from generation to generation (like a change in frequency of genotype)
5. With time, natural selection enables individuals to become better adapted to their environment
6. Environmental factors vary in time and space thus the selective forces are variable (summer vs winter, white-tail deers in Ontario+Quebec vs Costa Rica)
7. Traits in populations will change and can modify the species (change in morphology ie use of utensils means less pressure on our jaws thus they are becoming smaller)
How did Darwin justify the mechanism of natural selection as valid?
(What is differential reproductive success)
- Natural selection respects the principle of uniformity of Lyell and Hutton
- The results of natural selection are visible in nature
- Natural selection can be verified on current populations through artificial selection
- It is a materialistic concept (no need for divine intervention) because of two things, that:
a. Natural selection is not a random process and it enables individuals that are better adapted to their environment to become more abundant in the population than those who are not which is the idea of differential reproductive success
b. Natural selection is not a quest for perfection, evolution is not a directed process. It does not lead to the appearance of “perfect” traits. Organisms only adapt to their environment, some become more abundant in an environment or some traits are selected due to a predation factor ONLY TO ADAPT & SURVIVE
What is the difference between artificial selection and natural selection?
Artificial selection is finalized because the goal or objective, is fixed well in advance, and it precedes the cause. The end result can be obtained in a few generations. Natural selection is not finalized as it can take a long time for changes to occur, functions through geological time scale.
Provide an example for artificial selection.
Our food is artificially selected. A wild mustard plant that is artificially selected for its leaves is kale, for its apical buds is cabbage, for its auxiliary buds is Brussels sprouts. A mop dog is achieved by artificially selecting dogs with longer coats to breed.
Provide three examples of natural selection.
- Humans: adaptation to altitude in:
a. Andes: mutation for increase in hemoglobin concentration
b. Tibet Plateau: mutation (involving multiple genes) deeper breath, larger pulmonary capacity and increased blood flow
: genetically favoured in Plateau, as the abundance of individuals withstanding (genetic traits allowing for survival and reproduction in) high altitudes increased through time as they had differential mortality and reproductive rates - Medium Ground Finches: Climate (drought) in Daphne Major Galápagos Islands substantially decreased population because selection favoured individuals that had bigger and stronger beaks to break Available seeds during drought thus lowered abundance from small-beaked birds as limited reproduction and many died.
- Moths: selected in way of feeding. Dark morphs were more frequent on soot-infested trees (urban) while grey morphs were more frequent in countryside because of lighter coloured trees and predators were attracted to eating more vibrant food as it also easier to see (black/grey hereditary trait helped them camouflage depending on tree colour)
What do all cases of natural selection provide?
Natural selection provides the hereditary traits that give a reproductive advantage to individuals in a population will be favoured. Thus from generation to generation there will be a higher percentage of individuals carrying the adaptation. That is natural selection, Darwin’s descent with modification, evolution. These adaptations can sometimes redefine a species and rarely define into a new species.
