IISc study finds self-fertilization helps plants become invasive

IISc study finds self‑fertilisation helps plants become invasive

Researchers at the Indian Institute of Science (IISc) in Bengaluru have experimentally shown that a plant’s ability to self‑fertilise – reproducing without a partner – is linked to its invasiveness. The work, published in the journal Biological Invasions, examined 28 species from the daisy family (Asteraceae) collected from disturbed roadside and open habitats in Karnataka and Tamil Nadu over a year.

Seeds or cuttings from at least five individuals of each species were cultivated on the IISc campus, while a few hard‑to‑grow native species were observed in the field, giving a total of roughly 900 plants. The investigators, associate professor Saskya van Nouhuys of the Centre for Ecological Sciences and former MSc student Narashiman Nagendra Rao, compared seed set and germination after controlled self‑pollination versus natural cross‑pollination.

All eleven invasive Asteraceae species tested reproduced uniparentally, producing viable seeds when self‑pollinated. By contrast, the majority of the eight non‑invasive alien species and the nine native species remained self‑incompatible, requiring pollen from another individual. Two aggressive invaders, Ageratum conyzoides and Bidens pilosa, which are largely self‑incompatible in their Mexican native range, showed a clear shift to self‑fertility in Indian populations.

"Uniparental reproduction is a conceptually simple trait. It has been exciting to see such clear evidence of its advantage for invasive species,"

Saskya van Nouhuys, associate professor, Centre for Ecological Sciences, IISc (Deccan Chronicle)

"Before our experiments, the idea of reproductive strategies shifting during invasion seemed like a very far‑fetched idea to me and I thought that previous evidences of such shifts were very rare occurrences,"

Narashiman Nagendra Rao, former MSc student, Centre for Ecological Sciences, IISc (Rediff.com)

"The results from our experiments and that of our collaborators absolutely baffled me,"

Narashiman Nagendra Rao, former MSc student, Centre for Ecological Sciences, IISc (Rediff.com)

Van Nouhuys emphasized that invasive species “establish and then flourish in a new location” and that this rapid establishment “changes the whole landscape.” Both authors suggest that reproductive strategy should be incorporated into weed‑risk assessment programmes to help predict which introduced plants are most likely to become future invaders, echoing calls in the original report.

How the finding fits with broader research

A systematic review of 219 peer‑reviewed studies examined the role of asexual (including self‑fertilising) reproduction in invasions. The review found that asexual reproduction is about three times more common in invaded ranges than in native ranges, and that genetic diversity is roughly twenty times more common in home (native) populations than in invaded ones. The authors noted that asexual reproduction “confers several advantages for small founding populations,” such as the ability to establish from a single individual without needing a mate or pollinator.

The review also highlighted a potential downside: asexual reproduction “lacks the genetic mixing needed to respond to heterogeneous environments and natural enemies.” This trade‑off shows that while self‑fertility can aid initial establishment, it may limit long‑term adaptive capacity.

Implications

All sources converge on a practical recommendation: include breeding‑system information in invasive‑species risk assessments. The IISc team proposes routine testing of reproductive mode for newly introduced plants, and the broader literature supports the idea that self‑fertility is a key trait facilitating early invasion success.

Future work will need to test whether the pattern observed in Asteraceae holds across other plant families and ecological contexts, and to investigate the genetic mechanisms that enable rapid shifts toward self‑fertility during invasion.