Ch 17- Speciation Flashcards
This Species Concept assumes that a species is compromised of individuals that look alike, species classified on basis of appearance
Morphological species concept
The divergence of biological lineages and the emergence of reproductive isolation between lineages
Speciation
Two or more species are morphologically indistinguishable but do not interbreed
Cryptic species
Two groups of an organism can no longer exchange genes
Reproductive isolation
Concept that says that “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from such groups”
Biological species concept
What does the biological species concept not apply to?
Asexual organisms
What does the “actually” and “potentially” in the biological species concept mean?
Actually- the individuals live in the same area and breed with one another
Potentially- the individuals do not live I the same area but would breed together if they did
Concept that thinks of species as branches on a tree of life
Lineage species concept
An ancestor- descendant series of populations followed over time
Lineage
What are the two modes of speciation?
Allopatric and Sympatric
Speciation that results when a population is divided by a physical barrier (ex. Mountains, water)
Allopatric speciation
What is the other name for allopatric speciation?
Geographic speciation.
Speciation without physical isolation
Sympatric speciation
What is the most common mode of speciation?
Allopatric
What is the most common type of Sympatric speciation?
Polyploidy
What is polyploidy?
Duplication of sets of chromosomes within individuals
Type of polyploidy that arises from chromosomal duplication in a single species
Autopolyploidy
Type of polyploidy that arises from the combining of the chromosomes of two different species
Allopolyploidy
Mechanisms that prevent hybridization form occurring
Prezygotic Isolating mechanisms
Mechanisms that reduce the fitness of hybrid offspring
Postzygotic isolating mechanisms
Isolation due to the difference in the size and shapes of reproductive organs
Mechanical isolation
Isolation due to species mating at different times of the year or day
Temporal isolation
Isolation due to individuals failing to recognize other species as potential mating partners
Behavioral isolation
Isolation because the sperm of one species may not attach to the eggs of another species because the eggs do not release the appropriate attractive chemicals
Gametic isolation
A region of overlap in the ranges of two closely related species where the species may hybridize
Hybrid zone
Isolation due to two closely related species evolve preference for living or mating in different habitats
Habitat isolation
What is the most important factor in long term isolation of sexually reproducing lineages?
Reproductive isolation
