Chapter 17- Speciation Flashcards
Biological Species Concept
Based on reproduction
Morphological Species Concept
Based on appearance alone (phenotype). But is not reliable due to the subtle variations that are displayed
Species
One or more populations of individuals that are interbreeding under natural conditions and producing fertile offspring and are reproductively isolated from other such populations
Genetic changes between populations can only be encountered by what?
Gene Flow
Genetic Divergence
Differences build up between the gene pools of genetically separate populations
Reproductive Isolating Mechanisms
Any heritable feature of body, form, functioning, or behavior that prevents breeding between one or more genetically divergent populations
Pre-Zygotic Isolation
Mating or zygote formation is blocked
List the 5 types of Pre-Zygotic Isolations
- Temporal Isolation
- Behavioral Isolation
- Mechanical Isolation
- Ecological Isolation
- Gamete Mortality
Temporal Isolation
Different groups may not be reproductively mature at the same month, year, or season.
Behavioral Isolation
Patterns of courtship may be altered to an extent that sexual union is not achieved
Mechanical Isolation
Differences in reproductive organs prevent successful breeding
Ecological Isolation
Potential mates may be in the same general area but not in the same habitat where they are likely to meet
Gamete Mortality
Incompatibilities between egg and sperm prevent fertilization
Post-Zygotic Isolation
Occurs after members of two different species have mated and produced a hybrid offspring
Zygotic Mortality
Egg is fertilized but zygote or embryo dies
Hybrid Inviability
First generation hybrid forms but shows low fitness
Hybrid Infertility
Hybrid is fully or partially sterile
Allopatric Speciation
Physical barrier prevents gene flow between populations of a species
Sympatric Speciation
New species forms within a home range in the absence of physical barrier
Parapatric Speciation
Neighboring populations become distinct species. Hybrid Zone, daughter species formed by a common geographical border
Cladogenesis
Lineage splits resulting in genetic isolation and branching of species
Background Extinction
Local changing conditions
Mass Extinction
Catastrophic global event
Ex. Temperature changes, asteroids