Chapter 24: The Origin of Species Flashcards
Speciation
- Process by which one species splits into two or more species
- The “Mystery of Mysteries”
Microevolution
Changes over time in allele frequencies in populations
Macroevolution
Broad pattern of evolution above the species level
Biological Species Concept
- Concept that states a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
- These groups do not produce such offspring with other groups
Species
Population or group of populations whose members can interbreed and produce fertile offspring but do not produce viable, fertile offspring with members of other such groups
Reproductive Isolation
- Existence of biological factors (barriers)
- Hinders members of two different species from interbreeding and producing viable, fertile offspring
Hybrids
Offspring that result from interspecific mating
Prezygotic Barriers
- Block fertilization from occurring
- Impede the attempt of mating
- Prevent an attempt of mating from being completed successfully
- Prevent fertilization directly
Post Zygotic Barriers
Barriers to help reproductive isolation if the prezygotic barriers are bypassed and a zygote is formed
Morphological Species Concept
- Emphasizes the unity within a species
- Distinguishes a species by body shape and other structural features
- Mainly used by scientists but relies on subjective judgement
Ecological Species Concept
Defines a species in terms of its ecological niche
Ecological Niche
Sum of how members of a species interact with the nonliving and living parts of their environment
Phylogenetic Species Concept
Defines a species as the smallest group of individuals that can share a common ancestor
Allopatric Speciation
When gene flow is interrupted by populations being isolated into geographic subgroups
Sympatric Speciation
Speciation occurs in populations that occupy the same environmental area
Polyploidy
A chromosomal alteration in which the organism possesses more than two complete chromosome sets
Autopolyploid
- An individual that has > 2 chromosome sets that are all derived from a single species
- Can cause reproductive isolation without geographic separation
Allopolyploid
- A fertile individual that has > 2 chromosome sets as a result of two different species interbreeding and combining their chromosomes
- Fertile with each other but not with either parent species
Hybrid Zone
- Region where members of different species will meet and mate, which produces offspring with mixed ancestry
- Caused by a species with incomplete reproductive barriers coming in contact with another
Adaptive Radiation
Organisms diversify quickly from a common ancestor
Reinforcement
Process where natural selection strengthens prezygotic barriers because of the hybrids’ unfitness to the environment
Punctuated Equilibrium
- Pattern of evolution
- Long stable periods are interrupted by periods of more rapid change
Gradual Speciation
Species diverge gradually over time in small steps
Analogous Structures
Body parts that share a common function but not structure
Convergent Evolution
When different organisms independently evolve similar traits
Divergent Evolution
Process by which interbreeding species diverged into two or more evolutionary groups
Homologous Structures
Structures in different species that are similar because of common ancestry
Coevolution
Process by which two species evolve in response to changes in each other
