Unit 1 Flashcards
Adaptations
Inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.
Allopatric Speciation
The formation of new species in populations that are geographically isolated from another.
Analogous Structures
Having characteristics that are similar because of convergent evolution not homology.
Bottleneck Effect
- An example of Genetic Drift
- Size of population is reduced
- By natural disaster/human action
- Surviving population does not represent the original population (genetically)
Clades
A group of species that includes an ancestral species and all of its descendants.
Cladistics
- Organisms are placed into groups
- based on common descent
Conjugation
A temporary union of two organisms for the purpose of DNA transfer
Convergent Evolution
Process in which unrelated species from different environments have adaptations that seem very similar.
Directional Selection
- One extreme is favored or another
- To reproduce/survive
- Intermediate is never favored
Divergent Evolution
When two or more species sharing a common ancestor become more different over time
Disruptive selection
- Both extremes are favored
- To survive/reproduce
- Intermediate is not favored
Endosymbiont Theory
The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by host cells. The engulfed cell and its host cell then evolved into a single organism.
Evolution
- Descent with modification
- The change in the genetic composition of a population from generation to generation.
Founder Effect
- Genetic Drift
- When individuals are isolated from a larger population and form a new population
- Not reflective of original population
Gene Flow
- The transfer of alleles from one population to another.
- Immigration/Emigration
Gene Pool
All the genes/alleles present in a population
Genetic Drift
- A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
- More pronounced in sub populations
Hardy-Weinberg Conditions
- Extremely large population
- No Gene Flow
- Random Mating
- No Mutations
- No Natural Selectoin
Hardy-Weinberg Equations
p^2+2pq+q^2 = 1
p + q = 1
Hardy- Weinberg Variable P
Homozygous Dominant
Hardy-Weinberg Variable Q
Homozygous Recessive
Hardy-Weinberg Variable 2PQ
Heterozygous
Heterozygous Advantage
- Preserves generation in a gene pool
- Maintains recessive alleles in a populatoino
Homologous Structures
- Similar structures in different species
- Due to common ancestors
Natural Selection
- Individuals with certain inherited traits survive and reproduce
- Survival of the fittest
Nitrogen Fixation
Process of converting nitrogen gas into ammonia
Phylogeny
The evolutionary history of a species or group of related species
Relative Fitness
The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population.
Reproductive Isolation
The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring.
Shared Derived Character
An evolutionary novelty that is unique to a particular clade.
Speciaton
An evolutionary process in which one species splits into two or more species.
Species
- A group of similar organisms that can breed and produce fertile offspring.
- Sometimes different species can not reproduce
Stabilizing Selection
- Intermediate trait is favored
- Acts against extreme phenotypes
Sympatric Speciation
The formation of new species in populations that live in the same geographic area.
Vestigal Structures
- A structure that is present in an organism
- No longer serves its original purpose
