Lecture 11: Speciation Flashcards
What is a species?
Species is a population that is capable of interbreeding to produce healthy offspring that can themselves reproduce.
What are 6 reproductive barriers?
- Behavioural Isolation
- Mating Time Differences
- Habitat Isolation
- Mechanical Incompatibility
- Gametic Incompatibility
- Hybrid Weakness
What is behavioural isolation?
Members of a species often identify each other through specific rituals, markings, or smells.
For example: a peahen will only mate with a peacock who displays his large and colourful feathers
What is mating time differences?
Many species are able to reproduce only at specific times. Any attempts by members of another species to mate outside of this time frame will not be successful
For example: different species of toad will only breed at different times of year
What is habitat isolation?
If species live in slightly different habitats, they may never meet.
For example: there are three different species of bristlecone pine tress. Each one grows only in areas that are well separated from the other species by mountains.
What is mechanical incompatibility?
Members of different species often cannot mate because their anatomies are incompatible.
For example: in orchids, the pollen-bearing organs of many species have a specific structure that allows only one specific pollinator species to land and collect pollen
What is gametic incompatibility?
The gametes of different species usually cannot fertilize each other.
For example: multiple species of sea urchins live alongside each other, but the sperm of one species cannot fertilize the egg of another
What is hybrid weakness?
If two members of different species do manage to mate, a hybrid organism may result. Such hybrids may be unfit, or they may be sterile and unable to reproduce themselves, or may produce unfit offspring.
For example: a mule, a hybrid produced from a female horse and a male donkey, is always sterile
Which of the following describes the biological species concept?
A) groups of populations that are similar in body shape and other structures
B) groups of populations that interact in with their environment in similar ways
C) groups of populations that can successfully interbreed with one another
D) groups of populations that are on the same branch of the tree of life
C)
Consider the example of snakes we have discussed (same time, different space). How would you classify this type of reproductive barrier. Select the best response.
A) behavioural isolation
B) mating time differences
C) habitat isolation
D) mechanical incompatibility
E) gametic incompatibility
F) hybrid weakness
C)
Consider the example of the skunks we just discussed (different time, same space). How would you classify this type of reproductive barrier? Select the best answer.
A) behavioural isolation
B) mating time differences
C) habitat isolation
D) mechanical incompatibility
E) gametic incompatibility
F) hybrid weakness
B)
Which of the scenarios below is NOT a good example of pre-zygotic isolation?
A) Salamander species that breed on opposite sides of a lake
B) Sunflower species in the same area that produce flowers at different times of the year
C) Salmon whose eggs recognize the proteins on the sperm of another species and prevent fertilization
D) Nightshade species in the same area that produce zygotes that fail to develop
D)
Consider the post-zygotic examples we just discussed (hybrid inviability and hybrid sterility). Which pre-zygotic barrier is present in these examples?
A) behavioural isolation
B) mating time differences
C) habitat isolation
D) mechanical incompatibility
E) gametic incompatibility
F) none of them
D) mechanical incompatibility
Consider the example of the Threespine Stickleback (sympatric speciation). Which of the following reproductive barriers can you identify given ONLY what you know? Select all that apply.
A) behavioural isolation
B) mating time differences
C) habitat isolation
D) mechanical incompatibility
E) gametic incompatibility
F) hybrid inviability
G) hybrid sterility
A)
