evolution Flashcards
(23 cards)
Indigenous concepts
humans originated last of all of the living things and have the most to learn from other plants and animals.
Aristotle
ladder of life
Lamarck
thought individuals could get traits they needed
Cuvier
thought that organisms did not evolve over time because any change in an organism would make it unable to survive.
Malthus
thought that the human population would skyrocket if not for natural controls such as famine and disease
Charles Darwin
Species change, and this change is due to the environment selecting for certain traits, used artificial selection to prove that species can change
James Hutton and Charles Lyell
argued that the formation of Earth’s crust took place through countless small changes occurring over vast periods of time
Adaptive radiation
when many different species come from a common ancestor. Eg, Darwin’s finches that have many beak forms
Allopatric speciation
- when a population of a species is separated by a physical barrier
- the Darwin Finch is an example for allopatric speciation, geographical barrier was the ocean that separated the islands from south America.
Sympatric speciation
- when species form with no geographic barrier in place.
Species
group of living organisms that can interbreed and produce fertile offspring
Hybrid
offspring resulting from the crossbreeding of two different species, humans Intentionally breed for their own needs
Gradual model of speciation
new species arise slowly over time through small genetic changes
punctuated equilibrium model
speciation (a group within a species separates from other members of its species and develops its own unique characteristics) occurs rapidly in isolated populations
- Both Gradual model of speciation and punctuated equilibrium model models can coexist and explain different patterns of speciation in different species.
Micro evolution
Small-scale changes that occur within a population over time. It can be observed through changes in the frequencies of alleles.
Eg, pesticide resistance in insects
macro evolution
evolution on a large scale when enough of those small scale changes happen and new species are made
Mechanisms of Microevolution
Mutation- Random change to a gene’s DNA sequence.
Genetic drift- Random fluctuations in the frequency of alleles in a population over time. can lead to the loss of genetic diversity in a population.
Gene flow- Transfer of genes from one group to another as a result of interbreeding or migration. Can introduce new genetic variation into a population
Evolution acts use all of the following
- natural selection,
- Stabilizing selection, reduction in variation
- Disruptive selection, increases variation
- Directional selection, favors individuals with a particular trait that provides an advantage in a specific environment.
- Sexual selection, secondary sexual traits, like the peacock’s tail, or courtship dances for birds.
Hardy-Weinberg Equilibrium
- Very large population
- no migration
- no mutation
- no natural selection
- random mating
Rates of Macro-Evolution (Gradualism)
Gradualism (evolution by creeps)
- large evolutionary changes in a species occur slowly and steadily due to many small changes
- rate is constant
Rates of Macro-Evolution (Punctuated Equilibrium)
Punctuated Equilibrium (evolution by jerks)
- Major environmental events can cause rapid change/speciation followed by periods of little or no change
Rates of Macro-Evolution (Founder effects)
- Change in allele frequencies that result from a small number of organisms that inhabit a new area
- These organisms will not contain all genes of parent population
Rates of Macro-Evolution (Bottleneck Effect)
- Due to drastic reduction in population (natural disaster)
- Certain alleles will become over- or under-represented in future offspring
