Evolution and the Origin of Species Flashcards
Why is evolutionary theory considered to be the unifying theory of biology?
It is the framework that functions on the tenet that all life has evolved and diversified from a common ancestor which is the foundation from which all questions in biology are approached.
Describe how Charles Darwin and Alfred Wallace developed the present-day theory of evolution?
- Both of these individuals proposed the mechanism of natural selection in which prolific reproduction of individuals with favorable traits survive environmental change because of those traits, leading to evolutionary change.
- Charles Darwin’s most important work stems from observations made in the Galapagos Islands (finches / beaks).
- Alfred Wallace traveled the Amazon basin and was considered one of the fathers of biogeography.
(Fun fact: he also came up with a warning coloration that in animals. Fun fact.
What is natural selection?
Darwin’s Postulates:
1) Individuals in the population variant traits and these traits are inheritable
2) More offspring or produced than can survive
3) Individuals with the most favorable traits are more likely to survive and pass on those traits to the next generation
(Note: Fitness is a term used for being more likely to survive and reproduce)
(Summary: The population is the level upon which natural selection acts within a population. There is variation and sent to the individuals with the most adaptive treat survive. The population has more individuals with adaptive trait.)
What is descent with modification?
This is Darwin’s term for evolution, which is essentially natural selection that leads to changes in populations over generations.
Why was the work of Peter and Rosemary Grant so important?
They studied populations in the Galapagos islands since 1976, which provided important evidence for natural selection. After observing the beak sizes of the finches before and after El Niño, they noticed a decrease in size, due to have having to adapt to different food source (small vs. large seeds)?
(Note to self: huge leap from natural selection to evolution - no evidence of change in “kinds”)
How does genetic variation of a population occur? What is its importance on natural selection and evolution?
Mutation and sexual reproduction
Genetic variation is vital in order for selection to lead to change in the next generation.
What is a mutation? What are the three outcomes of mutations regarding natural selection?
Mutation is a change in DNA and the ultimate source of new alleles (alternate version of a gene).
Phenotype Mutation Type I: Reduced fitness
Phenotype mutation Type II: Increased fitness
Phenotype mutation Type III (neutral mutation): No effect on fitness
What is the difference between a genotype and a phenotype?
A genotype is the message on the DNA
Phenotype is the parent or behavior that results.
What is an adaptation and its role in natural selection? Why does this only occur at the level of population and not at the individual level?
A heritable trait that helps an organism’s survival and reproduction.
Adaptation refers to traits that are genetically determined in a species (not a specific individual acclimating) in order for that species to be adapted to the environment.
Describe the relationship between environmental conditions and natural selection
Whether a trait is favorable, depends on environmental conditions. The same traits are not always selective because environmental conditions can change. Therefore whichever traits are advantageous, depends on the environment
What is the difference between divergent and convergent evolution?
Divergent evolution is when two species evolved in diverse directions (different traits) from a common point.
Convergent evolution is where two species that do not share a common ancestry develop similar traits.
Describe the time span, which evolution of a species may occur according to biology?
-Millions of years
What are the four key types of evidence which support the theory of evolution?
The fossil record (preserved remains - demonstrates organisms are not the same today as they were in the past)
The anatomical and embryological record - (similar [homologous] structures and/or non function residual [vestigial] structures infer a common ancestor)
Biogeography - geographic distribution of organisms followed supercontinent (Pangaea) patterns
Molecular biology - DNA, proteins reflect descent with modification (very little diversification in DNA infers common ancestor for all life)
What are four key misconceptions about evolution and why?
- Evolution is just a theory: Misunderstanding of the word theory. In biology theory means something different than in common language.
- Individuals evolve: In biology, adaptation refers to natural selection. Whereas, acclamation is done by the individual.
- Evolution explains the origin of life: evolution only explains what happens after life.
- Organisms evolved on purpose: Evolution explains fitness and inherited genetics traits at the population level. These things are not controlled by the individual or species but instead then environment.
What is a species? What are some similarities, differences and exceptions?
A species is a group of organisms that combine genetic information through sexual reproduction (interbreed) resulting in viable offspring that are also able to successfully reproduce (in nature).
Members of the same species share external and internal characteristics which developed from their DNA
However, there are similarities and differences that occur, resulting in exceptions to this standard.
For example, species that might look the same may not be able to interbreed. Whereas, species that look different may be able to breed (hybrids). There are also species that reproduce through asexual reproduction.
