Biology Midterm Flashcards
Lamarck’s Hypothesis of Evolution
-Change through use and disuse: whatever was being used evolve on and whatever wasn’t being used disappeared
Example: Giraffes were constantly stretching their necks for leaves so they evolved long necks
Darwin’s Theory of Natural Selection & Evolution
- There must be variation in traits
- Traits must be heritable
- Survival must be non-random
If all of these are met, then a population may evolve over time
Information About Darwin
- Failed out of med school
- Naturalist on the HMS Beagle
- Created hypothesis about the Galapagos Finches
Descent with Modification
The theory that all organisms are related and descend from a common ancestor
Vestigal Structures
Structures that serve no purpose to the organism now but did for its ancestor
Convergent evolution
evolution of similar, analogous features in distant relatives
Endemic Species
Exist only in one geographic region
Ex) Darwin’s finches
Microevolution
A change in allele frequency in a population over generations
3 mechanisms that cause allele frequency change
- Natural selection
- Genetic drift
- Gene flow
Hardy-Weinberg Equation
Allele frequency = frequency of particular allele / total frequency
Genetic Drift
Random changes in allele frequencies from one generation to the next
Ex) founder effect and bottleneck effect
Founder Effect
Occurs when few individuals become isolated from a larger population
Bottleneck Effect
A sudden reduction in population size due to a change in environment
Relative Fitness
Contribution an individual makes to the gene pool of the next generation
Directional Selection
Favours individuals at one end of the phenotypic range
Disruptive Selection
Favours individuals at both extremes of the phenotypic range
Stabilizing Selection
Favours intermediate variants and acts against extreme phenotypes
Microevolution
Consists of changes in allele frequency in a population over time
Macroevolution
Refers to broad patterns of evolutionary change above the species level
Mechanical Isolation
Physical barriers like the shape of genitals
Postzygotic Barriers
Prevent the hybrid zygote from developing into a fertile adult
Morphological Species Concept
Defines a species by structural features
Ecological Species Concept
Views a species in terms of its ecological niche
Phylogenetic Species Concept
Defines a species as the smallest group of individuals on a phylogenetic tree
