Are non-native species larger in their invaded range? A test with tropical floodplain fish assemblages following inundation of a biogeographic barrier

作者：Lima Junior Dilermando P; Hoeinghaus David J; Bini Luis M; Agostinho Angelo A

来源：Biological Invasions, 2015, 17(11): 3263-3274.

DOI：10.1007/s10530-015-0951-y

• Body size
• Productivity
• Enemy-release hypothesis
• Natural experiments

There is a purported tendency for non-native species to have larger body sizes in their introduced range, commonly attributed to mechanisms such as enemy release or reduced competition. However, results are equivocal and this tendency may also result from ecosystem differences and/or the selective introduction of larger individuals. For most invasions it is difficult to separate the human from biological influences on body size. In this study, we utilize a natural experiment caused by the elimination of a semi-porous biogeographical barrier to test for body size differences in 12 Neotropical fish species in native and invaded ranges, unbiased by human influence in selecting introduced individuals. Our analyses include an additional 25 fish species native to both basins, enabling tests of consistency of body size patterns across native and non-native species in both ecosystems. Twenty-two species (9 non-native, 13 native), irrespective of life-history or trophic guild, had an interaction of population length-weight relationships which indicated inconsistency in relative body sizes in donor and recipient regions across age classes. Of the 15 species with similar slopes of the length-weight relationships between basins, all non-native species (n = 3) and five species native to both basins exhibited significantly larger body sizes (i.e. body mass at a given length) in the more productive donor ecosystem, and the remaining native species were either larger in the recipient system (n = 3) or were not significantly different between basins (n = 4). Our findings contribute to the growing literature that suggests perceived tendencies of larger body sizes in invaded ranges should not be generalized, especially when environmental conditions differ greatly among regions and when dealing with populations that exhibit significant age structure.

• 出版日期2015-11