Macroevolution Flashcards
What 5 “sub-theories” does Ernst Mayr claim Darwin’s Theory of evolution is composed of?
- Evolution as such
- Common descent
- Multiplication of Species
- Gradualism
- Natural Selection
What scale did Darwin stress that natural selection occurs at?
The organismal level
What contraints might channel evolution?
- Structural
- Developmental
Macroevolution
The study of the processes that cause biological lineages to split and the historical patterns that result from those splits.
- Lineages may consist of protein domains, tissues, species, or any other level of biological organization.
What two points does Steve Gould focus on within Darwinism?
- Gradualism
- Natural Selection
Hardy-Weinberg Equation
p2 + 2pq + q2
(When assumptions are met)
What are the major deviations from the Hardy-Weinberg Hypothesis?
- Natural Selection
- Gene Flow
- Genetic Drift
What are the consequences of gene flow?
Homogenize populations
- Homogeneous populations exchange alleles.
- Heterogeneous populations are isolated from each other.
Genetic Drift
The change in the frequency of a gene variant (allele) in a population due to random sampling.
What are the four postulates of natural selection?
- Individuals vary
- Some variation is heritable
- Not all individuals survive
- Differential fitness
What are some common misunderstandings of natural selection?
- Selection acts of individuals, though the consequences are seen in populations
- Selection acts on phenotypes but microevolution is the change in gene frequencies.
- Natural selection is not forward looking.
- Natural selection acts on existing traits.
- Natural selection is not random.
- Fitness is not circular (it is a statistical process).
What are two general ways to measure “evolutionary time”?
- Fossil/Stratigraphic record approximates evolutionary time
- Phylogeny
Operational Taxonomic Unit (OTU)
Complicated term for the name of a species at the end of a phylogenetic branch.
Polytomy
More than two branches stemming from a single node.
Trichotomy
A special type of polytomy involving three branches stemming from a single node.
Cladogram
A phylogeny in which branch lengths have no meaning.
Phylogram
A phylogeny in which branch length is proportional to change.
Ultametric Phylogram
Branch lengths are proportional to change or time (tips / leaves are at the same point)
Ancestral State
Any characteristic shared between one or more species and a common ancestor.
Why are phylogenetic trees used in biogeography?
To reconstruct the history of where species have lived.
Parsimony
A criterion used for creating phylogenies, where the fewest number of changes during evolution is the favored explanation.
Dollo’s Law
Complex characteristics are usually assumed to evolve the same way only one time.
- Exceptions (multiple origins of complex traits) indicate interesting evolutionary traits.
- One exception is that some distantly related fish have placentas (a complex trait whereby the mother nourishes her unborn young).
What are the five main uses of phylogenetic trees?
- Biogeography
- Ancestral State Reconstruction
- Tempo of evolution / timing
- Correlated Evolution
- Measure Biodiversity
Felsenstein Zone
Conditions under which parsimony is “positively misleading”.