Which statement best explains why some species increase in number after an environmental change?
Which factors can cause changes in population size? (Select 2.)
After irrigation to water crops was introduced in a dry region, mosquito populations increased. What best explains this change?
Why do scientists focus on population-level data rather than individual organisms when studying environmental change?
What is a reproductive barrier?
Which factors can act as reproductive barriers? (Select all that apply.)
Why is reproductive isolation important for the formation of new species?
Look at the picture. It shows how two different species of squirrels developed on the two sides of the Grand Canyon. How did the Grand Canyon contribute to speciation in squirrel populations?
Which of these is an example of how behavior can act as a reproductive barrier?
Reduced gene flow means:
The Central European blackcap is a small bird that spends its summers in Germany and Austria. For a long time, almost all of these birds flew southwest to warm Spain for the winter. But in the 1960s, people in Britain began putting out lots of bird feeders. This created an easy food source for any blackcaps that happened to fly northwest instead.
Birds with genes that pushed them toward Britain were able to survive the winter and return to Europe in the spring. Over many years, more and more blackcaps inherited these northwest‑migration genes.
This new route also changed how the birds find mates. The trip to Britain is shorter, so those birds return to Germany earlier in the summer. Because blackcaps choose mates as soon as they arrive, they usually pair with birds that took the same route. This has started to split the population into two groups based on where they migrate.
Which conclusion is best supported when reproductive barriers persist over many generations?
Which situation is most likely to lead to extinction of a species?
Which environmental change contributed to reproductive isolation in the Central European blackcap?
Which reproductive barriers are present in the blackcap example? (Select all that apply.)
Why do differences in migration timing reduce gene flow in blackcap populations?