Differences in life-cycle stage components between native and introduced ranges of five woody Fabaceae species.
Understanding differences in the components of life-cycle stages of species between their native and introduced ranges can provide insights into the process of species transitioning from introduction to naturalization and invasion. We examined reproductive variables of the germination (seed predation, seed viability, time to germination), seed output (crown projection, seed production, seed weight) and dispersal (seed weight, dispersal investment) stages of five woody Fabaceae species, comparing native and introduced ranges. We predicted that each species would differ in reproductive variables of at least one life-cycle stage between their native and introduced ranges, thus allowing us to determine the life-cycle stage most associated with invasion success in the introduced range. Acacia melanoxylon and Paraserianthes lophantha had reduced seed predation in their introduced ranges while P. lophantha also had higher seed viability indicating that the germination life-cycle stage is most strongly associated with their invasion success in the introduced range. Only Acacia longifolia varied between ranges for the seed output stage due to larger plant size, greater seed production and smaller seed size in its introduced range. Similar to A. longifolia, Acacia cyclops had smaller seed size in its introduced range but did not have any other variable differences between ranges suggesting that the dispersal stage is best associated with its invasion success in the introduced range. Surprisingly, Acacia saligna was the only species without a clear life-cycle stage difference between ranges despite it being one of the more invasive acacia species in Australia. Although we found clear differences in reproductive variables associated with life-cycle stages between native and introduced ranges of these five species, these differences were largely species-specific. This suggests that a species invasion strategy into a novel environment is complex and varies among species depending on the environmental context, phenotypic plasticity and genotypic variation in particular traits.