Exam 1 Flashcards
Divergent Species
Have common ancestors and have diverged from each other over time
Population bottleneck
Large populations pass through environment events that only a small number survive
Nonrandom mating that does not alter reproductive success does not result in evolutionary change. Why not?
The genotype frequency will be altered but not the allele frequency
Genetic Structure
The frequency of different alleles and genotypes in a population
Conditions in Hardy-Weinberg Equilibrium
- No mutation
- No selection among genotypes
- Population is infinitely large
- Mating is random
Types of selection
Disruptive, stabilizing, and directional
Locus
The point on a chromosome where two alleles exist
Phylogeny
The evolutionary history of the relationships between organisms
Taxon
A group of species that are designated with a name
Clade
A taxon that consists of all the evolutionary descendants of a common ancestor
Homologous features
Features shared by two more species that have been inherited from a common ancestor
Synapomorphies
Derived traits in a group of organisms that are evidence of their common ancestry
Convergent evolution
Independent evolution of similar features from different ancestral traits
Homoplasies
Traits that are present in multiple organisms but not in their common ancestor
Can come from convergent evolution or evolutionary reversal
Evolutionary reversal
The reappearance of an ancestral trait in a group that had previously acquired a derived trait
Data from which phylogenies are constructed
- Morphology
- Development
- Paleontology
- Behavior
- Molecular Data
How are phylogenies used?
- Reconstructing past events
- Understanding the evolution of complex traits
- Revealing convergent evolution
- Reconstructing ancestral states
- Molecular clocks help date evolutionary events
Monophyletic
A biological classification containing the common ancestor and all its descendants
Polyphyletic
A biological classification that contains multiple distantly related organisms but not the common ancestor
Paraphyletic
A biological classification that contains a common ancestor but not all of its descendants
Hardy-Weinberg Equation
(p^2)+2pq+(q^2)
Where p is the dominant allele and q is the recessive allele
How to find p or q
p=(2NAA+NAa)/2N
q=(2Naa+Na)/2N
Speciation
The divergence of biological lineages and the emergence of reproductive isolation between lineages
Species Concepts
- Morphological
- Biological
- Lineage
Cryptic species
Species that are morphologically similar but do not interbreed
Reproductive isolation
A state in which two groups of organisms can no longer exchange genes
Allopatric speciation
Speciation that results when a population is divided by a physical barrier
Sympatric speciation
Speciation that occurs without physical barriers
Polyploidy
The duplication of a set of chromosomes within individuals
Allopolyploidy
The possession of more than two chromosomes that are derived from more than one species
Autopolyploidy
The possession of more than two entire chromosomes sets that are derived from a single species
Examples of pre-zygotic mechanisms of reinforcement
- Mechanical isolation
- Temporal isolation
- Behavioral isolation
- Habitat isolation
- Gametic isolation
Post-zygotic mechanisms of reinforcement
- Low hybrid zygote viability
- Low hybrid adult viability
- Hybrid infertility
Hybrid zones
If reproductive isolation is not complete then closely related species may reproduce in areas where they are in contact
Traits used to classify organisms
- Behavior
- Morphology
- Molecularly
- Paleontology
- Development
Homologous traits
Traits that descended from a common ancestor (in two or more species)
Derived trait
A trait that differs from its ancestral form
Domain
Classification above kingdom
- Archaea
- Bacteria
- Eukarya
Factors influencing speciation rates
- Ecological
- Population bottleneck
- Type of population
- Environmental changes
- Sexual selection
Founder effect
The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestor
Methods of sympatric speciation
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