Data on aphids indicate that rarity in herbivorous insects may be a consequence of a low rate of potential population growth
Abstract
The most striking and consistent feature of rare aphid species isthat the period suitable for their development and reproductionis shorter than for the common species and, consequently, thepotential yearly rate of increase of these rare species is lower.Thus, in addition to the abundance of host plants determining theabundance of aphids (Dixon & Kindlmann, 1990), their potentialyearly population growth rates are also important.Contrary to current thinking, it is likely that many of thestriking differences in life-history traits of rare species areconsequences, rather than causes, of rarity, and have evolvedbecause they are rare.Like studies on rarity, those on invasiveness have also focusedmainly on differences in life-history traits of closely relatedinvasive and non-invasive species. This raises the question asto whether these differences are also a consequence, rather thanthe cause, of invasiveness.