Abstract
Biological invaders have long been hypothesized to exhibit the fast end of the life-history spectrum, with early reproduction and a short lifespan. Here, we examine the rapid evolution of life history within the harlequin ladybird Harmonia axyridis. The species, once used as a biological control agent, is now a worldwide invader. We show that biocontrol populations have evolved a classic fast life history during their maintenance in laboratories. Invasive populations also reproduce earlier than native populations, but later than biocontrol ones. Invaders allocate more resources to reproduction than native and biocontrol individuals, and their reproduction is spread over a longer lifespan. This life history is best described as a bet-hedging strategy. We assert that invasiveness cannot be explained only by invoking faster life histories. Instead, the evolution of life history within invasive populations can progress rapidly and converge to a fine-tuned evolutionary match between the invaded environment and the invader.
Highlights
Biological invaders have long been hypothesized to exhibit the fast end of the life-history spectrum, with early reproduction and a short lifespan
A long-standing hypothesis is that invasive populations will display fast strategies[2,3] along the fast–slow continuum[4,5,6], which will be characterized by early reproduction, and a short lifespan
Biocontrol females have a higher average daily fecundity than those from the other origins, but due to their shorter lifespan their total fecundity is lower than American females and not different from the others (Supplementary Table 2)
Summary
Biological invaders have long been hypothesized to exhibit the fast end of the life-history spectrum, with early reproduction and a short lifespan. Invaders allocate more resources to reproduction than native and biocontrol individuals, and their reproduction is spread over a longer lifespan This life history is best described as a bethedging strategy. A long-standing hypothesis is that invasive populations will display fast strategies[2,3] along the fast–slow continuum[4,5,6], which will be characterized by early reproduction, and a short lifespan. A wide cross-species comparison in birds[11] suggested that rather than a fast or slow strategy, a bet-hedging life history characterized by delayed reproduction and longer lifespan is linked to invasion. Research on an individual species enables evaluating whether invasive populations evolve along the fast–slow continuum or shift towards other kinds of life histories when compared with native ones.
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