Flashcards in Chapter 24 Deck (43):
How do prezygotic barriers block fertilization from occurring?
-stop different species from trying to mate
-prevent successful mating
-disrupt fertilization if mating works
Consists of changes in allele frequency in a population over time
Refers to broad patterns of evolutionary change above the species level
States that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.
Biological species concept
What does the biological species concept say?
A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring. They do not breed successfully with members of other populations.
The existence of biological factors, or barriers, that impede two species from producing viable, fertile offspring
The offspring of crosses between different species
When two species do not encounter each other at all (or very rarely) because they live in different habitats. They are not isolated by physical barriers,but they still do not encounter each other often because they live in different habitats
When species that breed at different times, seasons, or years cannot mix their gametes.
When behaviors that are unique to a species, such as courtship rituals, are effective barriers to mating.
When morphological differences can prevent successful completion of mating
When the sperm of one species may not be able to fertilize eggs of another species
List 3 post-zygotic barriers
1) reduced hybrid viability
2) reduced hybrid fertility
3) hybrid breakdown
What are the 5 types of isolation?
What are the two types of speciation?
Allopatric and sympatric
Gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations. Give an example.
Allopatric speciation; Example: the flightless cormorant (bird) from the Galapagos probably originated from a flying species on the mainland.
What are the 3 factors that can cause sympatric speciation to occur by reducing gene flow?
2) sexual selection
3) habitat differentiation
Is polyploidy (presence of extra sets of chromosomes) more common in plants or animals?
A species with multiple sets of chromosomes derived from different species
An individual with more than two chromosome sets, derived from a single species
A region in which members of different species mate and produce hybrids
The origin of new species
Broad patterns of changes in species
Speciation that happens in populations that geographically overlap
Extra sets of chromosomes because of accidents during cell division
List the 3 possible outcomes when species meet in a hybrid zone
T or F: Sometimes speciation requires change in one or many genes
Changes in allele frequency in a population over time
How is a hybrid created?
When different species breed
What are two forms of reproductive isolation barriers?
Prezygotic and postzygotic
What are some examples of prezygotic barriers?
Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation
What are some examples of postzygotic barriers?
Reduced hybrid viability, reduced hybrid fertility, hybrid breakdown
Gene flow is interrupted or reduced when a population is divided into geographically isolated sub-populations
Speciation that takes place in geographically overlapping populations
Periods of apparent status punctuated by sudden change
T or F: Regions with many geographic barriers typically have more species than regions with fewer barriers
Give two examples of viable offspring that surpass prezygotic barriers
What do biologists compare when grouping organisms?
Morphology, physiology, and DNA sequence
The making of a new species
What occurs when hybrids survive but are sterile?
Reduced hybrid fertility
Where reinforcement occurs, should reproductive barriers be stronger for sympatric or allopatric species?
Views a species in terms of its ecological niche
Ecological species concept