Chapter 24 Flashcards
Speciation
The process by which one species splits into two or more species
Microevolution
Changes in allele frequencies over time
Macroevolution
the broad pattern of evolution above the species level
Creates new species
Species definition
A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
Morphological species concept
Characterizes species by body shape and other structural features
Useful to use without knowledge of gene flow
Subjective
Ecological Species Concept
Views species within their niche
Categorizes based on interactions with biotic and abiotic components of its niche
Emphasizes natural selection filling new niches (disruptive)
Phylogenic Species Concept
Defined species as the smallest group of individuals that share a common ancestor
Hard to determine when two populations are different enough to be considered new species
Reproductive isolation
The existence of biological factors that impede members of two species from interbreeding and producing fertile offspring
Prezygotic barriers
Block fertilization from occuring
Postzygotic barriers
Contribute to reproductive isolation after a hybrid is formed
Habitat isolation
Two species may occupy different habitats in the same area and rarely encounter each other
Temporal isolation
Species are isolated by time
They breed different different times of the day or year
Behavorial isolation
Courtship rituals attract mates of the same species an d allow for species recognition
Rituals can prevent breeding with other similar types
Mechanical isolation
Mating is attempted by morphological differences prevent its successful completion
Gametic Isolation
Sperm of one species is not able to fertilize the egg of another
Reduced Hybrid Viability
Postzygotic
Genes of different parent species may interact in ways that do not allow hybrids to survive in the wild
Hybrid Breakdown
First generation hybrids are viable, but by the second generation they are frail
Hybrid defintion
Offspring of two separate species
Allopatric Speciation
Occurs when gene flow between a population is interrupted by a barrier
Predicts that populations of the same species that are geographically isolated should accumulate genetic differences
Sympatric Speciation
They are in the same area. Do not have geographic isolation
For example: yellow and orange flowers
Autopolyploid
Sympatric speciation
Creates a viable polyploid offspring
Habitat Differentiation
Sympatric speciation
Example: a new type of apple in an area creates a new species of flies specifically drawn to that new apple
Hybrid zone
The difference between two species. Where hybrids occur
If smaller, there is a better chance for the hybrid to survive
Reinforcement
Strengthening of reproductive barriers
Hybrids are not formed
Species are more and more different
Stability
Continued production of hybrid individuals
Fusion
Weakening of reproductive barriers
the two species fuse together
Punctuated equilibrium
Describes the sudden changes seen in the fossil record followed by long periods of stasis
New species are formed rapidly
