Biology 102 Chapter 3
self pollination or mating with plants that have undergone similiar polyploidy
plants with polyploidy can only reproduce with what?
barriers that allow a zygote to form but do not produce viable fertile adults
what are post-zygotic barriers
reduced hybrid viability, reduced hybrid fertility, hybrid breakdown
what are the three types of post-zygotic barriers
polyploidy, habitat differentiation, sexual selection
what are the three ways sympatric speciation can occur
an area in which members of different species mate and produce hybrids
what is a hybrid zone
when two populations of the same species become geographically isolates from one another due to a physical barrier eventually causing the gene flow between them to be interrupted
what is allopatric speciation
ancestral fish population was split into two by the formation of the isthmus of panama about 3.5 million years ago
what is an example of allopatric speciation
Maggot flies once fed solely on Hawthorn trees, but then as apple trees were introduced, certain populations of flies started to feed on apple trees only. Now, the two populations of flies do not interbreed.
what is an example of habitat differentiation
sperm of one species is not able to fertilize eggs of another species
what is gametic isolation
the apperance of new ecological niches
what is habitat differentiation
the first generation is alive and fertile but the second generation fails
what is hybrid breakdown
physical differences can prevent successful mating
what is mechanical isolation
a random event that leads to the presence of extra sets of chromosomes due to accidents during cell division
what is polyploidy
speciation happening suddenly over a short period of time
what is punctuated equilibrium
the existence of biological barrier that impede two species from producing viable fertile offspring
what is reproductive isolation
a form of natural selection in which individualds with certain heritable characyeristics are more likely than other individuals to obtain mates
what is sexual selection
speciation that occurs without the presence of a physical barrier
what is sympatric speciation
in plants
where does polyploidy most often occur
in geographically overlapping populations
where does sympatric speciation occur
the interruption of gene flow causes the population to evolve independent of one another
why does allopatric speciation occur
hybrids are better fit than purebreed species
why does fusion of barriers occur
neither purebreed species of hybrids are distinctively better
why does stability of barriers occur
a group of populations whose memebers have the potential to interbreed and produce viable fertile offspring
According to the biological species concept, what is a species
a reproductive barrier needs to interrupt gene flow between the existing species
What has to happen in order for speciation to take place
if speciation happens very slowly over several thousand generations
What is a gradual pattern of speciation
the flightless birds found on the galapagos islands
What is an example of speciation
Courtship rituals and other behaviors unique to a species make them not able to mate together
What is behavioral isolation
when species are in different habitats so they never encounter eachother and cant mate
What is habitat isolation
the hybrid is able to develop but are sterile
What is reduced hybrid fertility
the hybrid cannot stay alive
What is reduced hybrid viability
the process by which one speccies splits into two or more species is called speciation
What is speciation
When species are out at different times of the day, different seasons or different years so they don't encounter eachother and can't mate
What is temporal isolation
4,000-40 million years
What is the interval between speciation events
When hybrids are less fit than purebreed species
Why does reinforcement of barriers occur
Isolated from the rest despite the absence of physical barriers because other plants can no longer cross-pollinate to make offsprings with a plant with abnormal chromosomal numbers
after polyploidy happens in a plant, that plants end up being what?
prezygotic barriers, postzygotic barriers
What are the two types of reproductive barriers?
allopatric speciation and sympatric speciation
What are the two types of speciation?
peacocks with elaborate tails, elephants seals fighting over territories, and fruit flies performing dances
What are examples of sexual selection
barrier that block fertilization from occuring or prevent a zygote from forming
What are prezygotic barriers
habitat isolation , temporal isolation, behavioral isolation, mechanical isolation, gametic isolation
What are the five types of prezygotic barriers
reinforcement, fusion, stability
What are the three possible outcomes when closely related species meet in a hybrid zone
gradual pattern and punctuated equilibrium
What are the two rates of speciation
