A new study led by the University of Iowa has found that, for some invasive species aiming to conquer new territory, their success may lie in living fast and dying young. By examining a type of invasive snail that has become established in a variety of freshwater ecosystems worldwide, the experts discovered that the most successful invaders matured and reproduced much faster than their non-invasive conspecifics.
The freshwater mud snails studied by the scientists are native to New Zealand, and have spread all over the world (most likely through commercial ships at first), coming to dominate numerous lake and river ecosystems in North America, Europe, and Asia. Since the invasive snails reproduce both sexually and asexually, it can be used to better understand the advantages and disadvantages of sexual reproduction.
The scientists found that the asexual snails – with females reproducing without males by making genetic copies of themselves – have been the most successful invaders, although they have lower genetic diversity than those reproducing sexually. Moreover, these highly successful invaders had slower growth rates and were smaller in size than the sexual snails.
“It’s like these snails have this unusual constellation of traits that becomes almost ubiquitous in the invaders. So, that gets to the core question we’re asking, ‘What makes an invasive lineage invasive?’” said study senior author Maurine Neiman, a professor of Biology at Iowa. “I think the data suggest there seems to be a real advantage to this combination of slow growth rate and early reproductive maturity. Their generation times are faster, and they are likely to outcompete other snail lineages that mature more slowly.”
In the laboratory, Professor Neiman and his team grew populations of freshwater snails originally collected in Belgium and in six regions of the United States and examined their “life history traits” – the features related to their fitness and reproductive success that allows them to thrive in new environments.
“They grow up substantially faster than their New Zealand counterparts,” reported study lead author Carina Donne, a doctoral student in Biology at the Colorado State University. “That just shortens the whole life cycle. If you can make babies at a younger age, then all things being equal, your populations will grow faster.”
Further research is needed to discover the life history traits that make other invasive species successful. “A lot of invasive species research focuses on prevention measures. We have so many invasive species, once they’re there and established, it’s harder to get rid of them. If we can find some way to predict what would be good invasive species, we could implement prevention measures,” Professor Nieman concluded.
The study is published in the journal Oecologia.