ON SIZE AND AREA - PATTERNS OF MAMMALIAN BODY-SIZE EXTREMES ACROSS LANDMASSES

We describe a biogeographic pattern in which mammalian body size extre mes scale with landmass area. The relationship between the largest and the smallest mammal species found on different landbridge islands, mo untaintops and continents shows that the size of the largest species i ncreases, while that of the smallest species decreases, with increase in the area of the landmass. We offer two possible explanations: (1) t hat the pattern is the result of sampling artefacts, which we call the `statistical artefact hypothesis', or (2) that the pattern is the res ult of processes related to the way body size affects the number of in dividuals that a particular species can pack in a given area, which we call the `area-scaling hypothesis'. Our results point out that the pa ttern is not a statistical artefact resulting from random sampling, bu t can be explained by considering the scaling of individual space requ irements and its effect on population survival on landmasses of differ ent area.