In which situation is asexual reproduction most advantageous:
a) When the environment is constantly changing and large numbers of offspring are produced
b) When the environment is stable and benefits the species
Hmm I guess you could try and think about punctuated equilibrium to understand this type of question.
When the environment is stable, species use
sexual reproduction, resulting in genetic variability. They do this because
inevitable changes do occur (never assume they don't) and the question implies this if you think logically (since when do we get everlasting stability on Earth?). When these changes occur, the 'equilibrium' or stability is 'punctuated' and the most suitable variations are naturally selected. For this reason, sexual reproduction would be most advantageous in stable environments, and not asexual.
The environment is stable AND benefits the species. Therefore with asexual reproduction, ALL the offspring have the favourable characteristics - genetic variability is NOT needed, as the environment is unchanging and already benefits the species.
You assume that once a stable environment is reached, it lasts forever. If it did, then yes, asexual reproduction is advantageous. But if variations did not arise during stability, we would have nothing being naturally selected when, not if, an adverse change comes through.
Moreover, most forms of asexual reproduction are fast methods of reproducing ones self (e.g. binary fission). Since when is fast reproduction to maintain the survival of a species required in a stable state?
Just one final bit of logic. The environment right now is
relatively stable. Cloning is essentially asexual reproduction. Since this is so, would we clone (using tissue culturing) all of the species of crops we depend on for survival because, right now, the stable conditions favour them? What if the conditions turn - we are out of vital crops.
In MC you choose the
best answer, and in this case, I would agree with your teacher. (by the way, is this prelim? because i remember getting the exact same mc wrong in prelim)
Sorry for the essay, but I hope you will read it and genuinely consider my opinion.
EDIT: I guess you could interpret the question to be a hypothetical situation of perpetual stability... but I would always assume it applies to real life logic so yeah... dunno