List of top Ecology and Evolution Questions

Which one of the following makes a species most vulnerable to extinction?
Two sister species of bulbuls have non-overlapping distributions. One is distributed in India and the other in Sri Lanka. Which of the following modes of speciation is the most parsimonious explanation for this pattern?
Which one of the following mammalian DNA regions exhibits the highest level of sequence variation?
In an Arctic Ocean food chain, killer whales feed on sea otters, which feed on sea urchins, which in turn feed on kelp (a type of seaweed). An increase in the abundance of killer whales causes sea otter abundance to decline, leading to higher sea urchin densities, which in turn reduces the abundance of kelp. Which of the following terms describes this phenomenon?
Which one of the following Mendelian disorders is influenced by diet?
Of the following, which one is the most direct measure of Darwinian fitness?