Exam 1 Flashcards
(48 cards)
What different ideas from the idea of special creation did Darwin publish On The Origin of Species by Means of Natural Selection in 1859
- Species are independent
- Life on earth is young
- Species are immutable (incapable of change)
What 2 components are scientific theories comprised of
- Pattern (observations abt natural world)
- Process (mechanism that produce that pattern)
What were Plato’s thoughts
Every organism was an example of a perfect essence, or type, created by God (typological thinking)
What were Aristotle’s thoughts
- Great chain of being
A. Sequence started with minerals and lover plants
B. Humans were at the top of the chain
Species were fixed types as Plato proposed
Some species are higher in the sense of being more complex/better - than others
Lamarck’s ideas on evolution
Suggested that the process responsible for this pattern was the inheritance of acquired characters
Ex: giraffes develop long necks from stretching to reach food and produce offspring with long necks
What are homologous
A similarity that exists in species descended from a common ancestor
The 3 different levels of
1. Genetic
2. Developmental
3. Structural
Genetic homology
A similarity in the DNA nucleotide sequences, RNA nucleotide sequences or amino acid sequences
Developmental homology
Seen in embryos of different species
Ex: tails & gill puches found in the embryos of chickens, humans, and cats
Structural homology
A similarity in adult morphology
Ex: most vertebrates have a common structural plan in the limb bones
Speciation
A process that that results in one species splitting into 2 or more descendant species
Darwin’s 4 postulates
- Variation- Individuals in a population vary in their traits
- Heritability- Some of these differences are heritable; they are passed on to offspring
- Overproduction- In each generation many more offspring are produced than can survive
- Differential survival- Individuals with certain heritable traits are more likely to survive and reproduce
Biological fitness
The ability of an individual ti produce surviving fertile offspring relative ti that ability in other individuals in the population
Biological adaptation
A heritable trait that increases an individual’s fitness in a particular environment relative to individuals lacking that trait
Biological selection
Differential reproduction as a result of heritable variation
Natural selection
Increases the frequency of alleles that contribute to reproductive success in a particular environment
Genetic drift
Causes allele frequencies to change randomly
Gene flow
Occurs when individuals leave one population, join another, and breed
Mutation
Modified allele frequencies by continually introducing new alleles
Natural selection occurs when
Heritable variation leads to differential survival and reproduction
If the favored phenotype is associated with certain alleles
Genetic variation
The number and relative frequency of alleles that are present in a particular population
What variety of patterns or modes does natural selection occur?
- Directional selection
- Stabilizing selection
- Disruptive selection
- Balancing selection
Directional selection
Changes the average phenotype in the population in one direction (tends to reduce the genetic diversity of populations)
Stabilizing selection
Reduces genetic variation in a trait but does not change average value of a trait over time (reduce both extremes in a population)
