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AP Bio Unit 7 Vocabulary - Evolution Unit
Phylogenetic Tree: Node (point)
Common Ancestor
Abiotic
Non-living part of ecosystem
Biotic
Living Part of Ecosystem
Darwin’s Postulates
Members of a species vary from one another
Some phenotypic variation is heritable
Organisms compete for resources in nature, driving evolution
Variations that increase survival and reproduction will be passed on
Convergent Evolution
Process by which two different species with no recent common ancestor evolve similar traits in response to similar environmental pressures
Stabilizing Selection
Selects for the status quo instead of extremes, keeping a stable, average trait over time
Directional Selection
As the environment changes, selective pressure pushes certain traits in a direction.
Disruptive Selection
Favors extremes over intermediates, (like different feeding months), eventually leads to speciation
Artificial Selection
Process by which humans select for traits, breeding
Sexual Selection
Form of selection that finds and selects traits that increase an individual’s ability to find mates.
Intrasexual Selection
Competition (typically between males) to attract females, leading to evolution of certain traits (ones that winning males have)
Evolutionary Fitness
Depends on the ability to have offspring who can reproduce for more offspring
Germ-line cell mutations
Passed down to offspring
Somatic Cell Mutations
Just in the parent, not passed to offspring
Genetic Drift
Chance decides which organisms survive, not adaptability
Bottleneck Effect
Random event kills like half the population → disproportionate alleles represented in the ones that survived not because adaptability
Small populations much more affected
Founder’s Effect
The few organisms that founded a population in a new environment may be disproportionally represented in the population (genotype)
Extinction: Who’s more vulnerable?
Inbred populations, small populations, low genetic variability → less genetically varied organisms have less of a chance that one makes it through pressures and reproduces
Balancing Selection
Two or more alleles maintained in a population at an intermediate rate (heterozygotes and malaria)
Oxidative atmosphere
Our current atmosphere with oxygen
Reductive Atmosphere
Ancient earth, no oxygen gas
Miller Experiment
Primitive gasses + spark = amino acids
RNA World Hypothesis
Natural evolution in RNA, traits were selected for → RNA forms a complement DNA strand → DNA is more stable
Cambrian Explosion
Ice caps melted and many marine organisms developed
Homologous Evolution
Similar traits because of a common ancestor
Analogous Evolution
Traits similar because of convergent evolution
Evidence for Evolution
Fossilization
Vestigial structures
The genome (everything has ribosomes, same AA coding)
Biogeography
Embryology (same development process)
DNA vs Protein for common ancestry evidence
DNA, exons can be spliced and same protein can be made by diff. DNA
Molecular Clock
Tool used to estimate rate of evolution
Problems with the Fossil Record
Needs to be buried shortly after death, needs hard tissues
Speciation: Biological Species Concept
Species are groups of species that are able to interbreed, can exchange genetic material through offspring
Problems: Biological Species Concept
Asexually reproducing organisms, practicality (how can we test if they will mate), regions where species may interbreed but not others
Speciation: Morphospecies Concept
Looks at phenotypes of species to classify them, similar DNA sequences
Morphospecies Concept: Problems
Different species may look the same, same looking may not be able to breed because different species → contrasts the BSC
Reproductive Isolation: Prezygotic Factors
Before/During Fertilization: geographic, ecological, temporal (reproduces at diff. times), behavioral, gametic (gametes are incompatible), mechanical
More efficient, doesn’t use energy to make bad offspring
Reproductive Isolation: Postzygotic Factors
Hybrid Invariability - embryo doesn’t fully develop
Hybrid Sterility - sterile offspring produced (ex. mules)
Allopatric Speciation
“Different Place” populations
Adaptive Radiation
Rapid speciation into many diverse groups after a major disaster or extinction
Sympatric Speciation
A new species develops within the same habitat because of growing changes in behavior (ex. because of disruptive selection)
