Evolution (Exam 2) Flashcards
Darwin
- Went to Galapagos islands on world tour where he collected species and noticed the birds differed on each island.
- observed that endemics are usually most closely related to mainland species despite environmental differences.
- He published “on the origin of species by means of natural selection”.
- His beliefs were influenced by fossils
- descent with modification
founder effect
Occurs when a new population is started by only a few individuals that do not represent the gene pool of the larger source population.
Endemics
A species found in a single location, and no one else in the world, usually most closely related to nearest mainland
Empirical thought
Relies on observation to form an idea or hypothesis rather than trying to understand life from a nonphysical/spiritual point of view
“On the origin of species by means of natural selection”
A book published by Charles Darwin where he connected all the known facts of evolution. He made 2 points:
- Today’s organisms transcended from ancestral species
- Natural provided a mechanism for evolutionary change in populations
This challenged beliefs that were centuries old
Classical greek philosophers who opposed evolution
Plato: Believed in two worlds, one real world that is ideal and perfect and an illusory world that we perceive through our senses
Aristotle: Believed that all living forms could be arranged on a ladder of increasing complexity, species are permanent and “perfect”
Georges Cuvier
A french anatomists who largely developed early paleontology. He advocated catastrophism and recognized extinction was common in the history of life.
Catastrophism
Advocated by Cuvier, it is the concept that boundaries between strata in the ground were due to local flood or drought that destroyed the species present at the time. This was later repopulated with species from unaffected areas
Radiometric dating
Method used to determine absolute ages of fossils by analyzing radioactive isotopes
Gradualism
Theory that profound change results from slow, continuous processes. Advocated by James Hutton
James Hutton
A Scottish geologist who advocated gradualism, in contrast to Cuvier and catastrophism. He also proposed that diversity of land forms could be explained by mechanisms currently operating
Uniformitarianism
Theory proposed by Charles Lyell that geological processes had not changed throughout earth’s history
Which scientists had a big influence on Darwin and how?
Hutton and Lyell.
1. If geological changes are gradual, earth must be older than 6000 years old(believed age of earth at the time)
- Slow, subtle processes can add up to substantial change
Lamarck
First to suggest evolution/that species arent fixed, acquired traits, use/disuse
Linneaus
Classification system that assumes species are fixed
Ernst Mayr(general)
Evolutionary biologist who dissected Darwin’s theory into 3 inferences based on 5 observations
Darwin’s observations as described by Mayr
- Large amount of fecundity
- Population tend to be stable in size
- Resources are limited
- No individuals are alike, large amount variety
- Much variation in a population is heritable
3 Inferences of Darwin’s theory as dissected by Mayr
- Only some offspring from each generation survive. Reproducing more than an environment can handle creates a survival struggle
- Survival is not random, survival of the fittest
- Unequal ability of individuals to survive and reproduce will lead to a gradual change in the population, with favorable characteristics emerging
3 main ideas of Darwin
- Natural selection is differential success in reproduction
- Natural selection occurs through an interaction between the environment and the variety inherent among the individual organisms making up a population
- Adaptation is a product of natural selection
Thomas Malthus
Heavily influenced Darwin’s veiws on overreproduction by writing an essay contending that human suffering was the inescapable consequence of human overpopulation
Differential reproduction
Organisms with traits favored by the environment reproduce more than organisms without those traits
Darwinian view of life
- Diverse lifeforms have arisen by descent with modification from ancestral species
- The mechanism of modification has been natural selection working over time
Fecundity
tendency to produce more than the environment can support
Homology
similarities in characteristics resulting from common ancestry
Homologous structures
similar structures in different species because of common ancestry
Vestigial organs
homologous structures that have little or no importance to a current organism but was important in its ancestors
Convergent evolution
2 different species from different lineages show similar characteristics because they occupy similar environments
Analogous structures/species
Similar structures/traits resulting from convergent evolution