by Ali Siddiqui
Rühl et al. (2015) writing in Biological Conservation attempted to determine whether predicted changes in temperature as caused by global warming would be detrimental to the survival of endangered arable weed species, which play an important role in increasing biodiversity. The results of the study were multiple. The authors concluded that endangered arable weed species germinated significantly less than the common arable weed species under increased temperature conditions and preferred lower optimal germination temperatures (24°C ± 3.5) than common arable weed species (31°C ± 0.5).
The researchers also found that common arable weed species tended to have greater flexibility when it came to changes in water potential for the seeds. The conditions for endangered arable weed species to germinate successfully were therefore much narrower than the common arable weed species. In fact, the scientists even discussed different germination strategies employed by common arable weed species to avoid complete failure of all seedlings’ germination.
The importance of temperature change on species’ ability to germinate was extended to incorporate long-term consequences. The authors showed how flexibility to temperature change for germination by some species has allowed those species to maintain population size, whereas other species have undergone a reduction.
The arable weed species have an unfavorable genetic structure comprising of low genetic diversity and high differentiation between populations, which leaves them to an unpromising future with predicted climate change. The evolutionary response of the common arable weed species to become more flexible to rapidly changing environments as a consequence of coexisting with crops was suggested a possible explanation for the difference between the germination success of the endangered arable weed species that does not coexist with crops, and the common weed arable species.
The paper ended by drawing on the larger question as to how this complex interplay between climate change and the survival of endangered species with unfavorable genetic structures will play out.
Rühl, Theresa A., Eckstein, Lutz R., Otte, Annette, Donath, Tobias W. 2015., “Future challenge for endangered arable weed species facing global warming: Low temperature optima and narrow moisture requirements.” Biological Conservation 182, 262-269.