A critically endangered dolphin is currently restricted to a relatively small stretch of coastline. The dolphins are "captured" by just collecting samples of DNA and "tagged" by identifying their DNA fingerprint. A 2010-2011 capture-recapture study "captured" and "tagged" 27 dolphins in 2010. In 2011, 29 dolphins were "recaptured" and through their DNA, 9 were identified as having been "tagged" in 2010. Based on the standard capture-recapture formula, estimate the population of dolphins in 2011.

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .