Could recent increases in atmospheric CO₂ have acted as a selection factor in Avena fatua populations? A case study of cultivated and wild oat competition

Abstract

Projected increases in atmospheric carbon dioxide concentration [CO 2 ] may lead to differential selection and competition between weeds and crops. Yet, the current level of atmospheric [CO 2 ] already reflects a rapid rise (~25%) from mid-20th century levels. To assess whether this increase could have already resulted in differential selection between weeds and crops, two temporally distinct populations of Avena fatua (wild oat) from the same geographic location, one from the 1960s (WO old ) and one from 2014 (WO new ), were grown with and without a cultivated oat (CO) line, Clintland 64 (Avena sativa) at current and mid-20th century [CO 2 ] levels (ca 320 and 402 lmol mol À1 respectively). Monocultures of each WO population differed in their response to recent increases in atmospheric [CO 2 ], with WO new showing a significantly higher response for all vegetative parameters relative to WO old . Assessment of competitive outcomes indicated that at 315 lmol mol À1 cultivated oat was at a competitive advantage relative to either A. fatua population for leaf area and total above-ground biomass. However, at current levels of CO 2 , an overall increase in WO new competitive ability was observed relative to the cultivated oat line. Overall, these differences are consistent with, but not conclusive for, improved evolutionary fitness and increased early competitive ability of A. fatua relative to cultivated oat as a function of the recent increase in atmospheric [CO 2 ]. While additional empirical studies are needed, these preliminary results indicate that weeds may be adapting rapidly to rising levels of atmospheric carbon dioxide.

Climate Change, Carbon Dioxide, and Pest Biology, Managing the Future: Coffee as a Case Study

“…For example, Rodriguez-Trelles and Rodriguez [130] have documented adaptation to climate change in Drosophila subobscura Collin. Similar evolutionary adaptation has been suggested for plant pathogens [32,34] and weeds [131,132]. In contrast to pests, economic pressures often limit host genotypes to a narrower genetic range [133], limiting evolutionary response to climate and/or CO 2 .…”

Elevated [CO2] effects on crops: Advances in understanding acclimation, nitrogen dynamics and interactions with drought and other organisms

“…There are further concerns that weeds might be evolving more quickly to take advantage of e[CO 2 ] than we are able to achieve in crop breeding programmes, and might thus represent a larger problem in the future (Ziska ). Weed populations generally show high genetic diversity compared to crop plants and are subject to natural reproductive processes and selection pressures.…”

“…As such, weed populations have access to a larger number of alleles to adapt to the e[CO 2 ]. This has raised the question whether weed adaptation to e[CO 2 ] might already be happening (Ziska ). Obviously, evolutionary processes take time, but these early indications, in addition to other concerns raised previously, point to weed problems becoming potentially more important in many cases.…”

Crop Adaptation: Weedy and Crop Wild Relatives as an Untapped Resource to Utilize Recent Increases in Atmospheric CO2

“…Greater seed yields were also recorded for Stuttgart, a CWR to rice, compared to Clearfield, a cultivated rice line, for the same recent CO 2 increase [32]. Similarly, using a resurrection approach [33], seeds of two temporally distinct populations of CWR wild oat (Avena fatua L.) from the same location, one from the 1960s and one from 2014, (a relative CO 2 increase of 80 ppm, or 25% from 1960) demonstrated different competitive abilities against a cultivated oat (A. sativa) line, with the more recent (2014) A. fatua population having greater growth and competitive ability at current CO 2 levels [34].…”