lecture 13 Flashcards
hypothetical examples of natural selection
Hypothetical examples of natural selection: mouse who is diploid and has fur length locus, they live just over one year and each pair of mice prepares some offspring. Half of the alleles are S and half are L alleles.
Evolution:
Evolution: may be defined as a change in allele add from lab manual
Natural selection does not result in what?
Natural selection does not result in evolution does not result in evolution if the characteristic is not inherited
Modes of selection
Directional selection, stabilizing selection, disruptive selection
Directional selection
Directional selection is natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully more than other individuals.
Stabilizing (balancing) selection
Stabilizing (balancing) selection: Naturals selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.
Disruptive selection
Disruptive selection: Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.
What is natural selection the result of?
Natural selection is the result of different rates of reproduction.
Natural selection acts as?
Natural selection often acts through survival because the individual generally must survive to reproduce and can also act through access to mates.
Sexual selection
is natural selection that acts through access to mates. This is a subtype of natural selection.
What term did Darwin coin?
Darwin coined the term sexual selection. Peacock example. But the attractive peacocks are easier to kill. Increases mortality and increases ability to mate.
What drives the evolution of adaptations?
Natural selection (including sexual selection) is the only mechanism that we know about that drives the evolution of adaptations.
Adaptations:
Adaptations: Inherited characteristics of an organism that enhances its survival and reproduction in a specific environment.
What can evolution be driven by?
Evolution can also be driven by genetic drift.
genetic drift
Genetic drift: Changes in allele frequency due to chance.
What type of process is evolution by natural selection?
Evolution by natural selection is an opportunistic process.
It is not a perfecting process
Speciation
Speciation: The evolution of reproductive isolation within an ancestral species, resulting in two or more descendant species. Is often gradual. After many generations, perhaps interbreeding is still possible but sometimes fails. After some more generations, interbreeding may be impossible.
Geographic isolation
Independent evolution:
Each group is evolving on its own, those traits become more and more different with each generation.
Gradual reproductive isolation:
ADD DEFINITION Example of the river separating two populations. Two populations evolving independently.
Species
Species: Biological species concept. A species is a group of organisms that can potentially interbreed successfully. This definition applies to organisms that reproduce sexually.
RNA world hypothesis
There were nucleotides and RNA forms. RNA can act as an enzyme. Some enzymes caused the replication of RNA. Once its copying itself, variation will happen and selection will favour the best RNA. SELF COPYING RNA WAS THE FIRST STEP IN THE DEVELOPMENT OF LIVING UNIT.
Major domains of life
Bacteria, Archaea, and Eukarya are the three major domains of life
Organisms can be characterized by
Organisms may be characterized by their nutrition.
Autotrophs
Auto: self trophs: feeder. They get their carbon by carbon dioxide and it uses that to build its own organic molecules.
Heterotrophs
Other feeders. Obtains organic carbons from organic molecules. Humans are heterotrophs. Heterotrophs get their carbon by consuming food.
Phototrophs
Light eaters. Obtain energy from light. This is chemical energy. Energy that can be used for metabolic reactions. For example, plants.
Photoautotrophs
Obtain carbon from carbon dioxide and energy from light.
Chemoautotrophs
Obtain carbon from carbon dioxide and energy from chemicals.
Chemoautotrophs
Obtain carbon from carbon dioxide and energy from chemicals.
Photoheterotreophs
Obtain carbon from organic molecules and energy from light.
Chemoheterotrophs
Chemoheterotrophs: Obtain carbon from organic molecules and energy from chemicals
Chemotrophs
Chemical eater. Obtain energy from chemicals.
Organisms can be characterized by type of
Organisms can be characterized by type of reproduction: Sexual and asexual
Sexual:
Haploid cells (gametes) fuse to form a zygote.
Asexual:
There is no fusion of haploid cells (gametes).
