Why do we expect that postzygotic isolation will evolutionarily precede prezygotic isolation in the speciation process?
What will be an ideal response?
Postzygotic isolation is fitness-reducing in that mating effort is wasted on offspring that have low survivorship or fecundity. Natural selection should act to reduce this waste by favoring, for example, mate recognition signals or spatial or temporal partitioning that prevent such matings in the first place.
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In multiple sclerosis the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results. How does this disease manifest at the level of the action potential?
I) Action potentials move in the opposite direction on the axon. II) Action potentials move more slowly along the axon. III) No action potentials are transmitted. A) only I B) only II C) only III D) only II and III E) only I and II
Pioneering species inhabiting a disturbed area alter the environment and create new habitats
a. False, the habitat cannot be changed by a living organism. b. True, organisms moving to a disturbed area use the resources and can themselves be a resource or can provide resources such as shade. c. False, pioneering species are very short-lived and so do not invest enough time to change the habitat
What would you expect to observe in a species with a promiscuous mating system?
A. Males remain with females to help raise young. B. Females interfere with any attempts by males to mate with other females. C. Intrasexual selection is very strong, with larger males. D. Intrasexual selection is very strong, with larger females. E. A female mates with a different male in every breeding season.
Assume that a man who carries an X-linked gene has children. Assuming normal meiosis and random combination of gametes, the man would pass this gene to ________
A) all of his sons B) half of his sons C) all of his children D) half of his daughters E) all of his daughters