Final answer:
Estimating the total population size by extrapolating from a sample can lead to either an overestimate or underestimate, especially when the species has a clumped distribution. Without additional information about the density variations across all the clumps, it's impossible to determine whether the estimate of 25,000 individuals is accurate.
Step-by-step explanation:
When you sampled a cluster of trees covering 200 km2 and caught 1,000 individuals of the insect species, you found that the density of this insect within that clump was 5 individuals per km2 (since 1,000 divided by 200 equals 5).
If you extrapolate this density to the entire 5,000 km2 without considering possible variations in insect density throughout different clumps or the entire area, you would estimate a total population size of 25,000 individuals (since 5 multiplied by 5,000 equals 25,000).
However, because the trees (and therefore, presumably, the insects) have a clumped distribution, this method of extrapolation might not be accurate. If the density of insects varies significantly between clumps, an overestimate or an underestimate of the total population size can occur. If the sampled clump had a higher density of insects than the average across all clumps, it would result in an overestimate. Conversely, if the sampled clump had a lower density, it would lead to an underestimate.