Evolution of natural algal populations at elevated CO₂

Abstract

Over the next century, it is expected that the concentration of CO(2) in the atmosphere will roughly double (Watson et al., 2001, Climate Change 2001: the Scientific Basis, Intergovernmental Panel on Climate Change, Geneva). Microbial populations, which have large population sizes and short generation times, may respond to CO(2) enrichment through genetic change. Here we describe microalgae isolated from the soil of natural CO(2) springs and compare these strains with lines of Chlamydomonas that were selected at elevated CO(2) in the laboratory. Both the laboratory and natural populations failed to evolve specific adaptations to elevated CO(2), and contain populations that grow poorly at ambient levels of CO(2). Laboratory and CO(2) spring populations also include lines whose growth rates are insensitive to CO(2). This demonstrates that, although laboratory selection experiments use simplified environments, the evolutionary responses that are seen following long-term CO(2) enrichment correspond to those found in natural populations that have experienced similar conditions.

Adaptation by macrophytes to inorganic carbon down a river with naturally variable concentrations of CO 2

“…Genotypic change is possible given the potentially large number of 334 generations that could have occurred at this site over thousands of years. However, a study 335 of soil algae at two high CO 2 (aerial) springs, found little evidence for genetic adaptation to 336 high CO 2 concentrations (Collins and Bell, 2006). The ability of plants such as B. erecta to 337 grow well in rivers is strongly linked to the high concentrations of CO 2 that can sometimes be A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t M a n u s c r i p t A c c e p t e d M a n u s c r i p t M a n u s c r i p t M a n u s c r i p t Table 1.…”

Long-term culture at elevated atmospheric CO2fails to evoke specific adaptation in seven freshwater phytoplankton species

“…Some lines evolved higher rates of photosynthesis, but these were offset by photorespiration and carbon leakage from the cell [23]. Some high-CO 2 selection lines grew slowly at ambient CO 2 concentration, as do natural populations of soil algae collected from CO 2 springs [23]. Further experiments suggest that the evolution of strains differing in their response to elevated CO 2 is constrained by competition with other strains [24].…”

“…Long-term experiments with the unicellular chlorophyte Chlamydomonas reinhardtii failed to show any specific adaptation to elevated CO 2 [10]. Some lines evolved higher rates of photosynthesis, but these were offset by photorespiration and carbon leakage from the cell [23]. Some high-CO 2 selection lines grew slowly at ambient CO 2 concentration, as do natural populations of soil algae collected from CO 2 springs [23].…”

Phytoplankton responses and associated carbon cycling during shipboard carbonate chemistry manipulation experiments conducted around Northwest European shelf seas

“…The temporal scales applied in all field experiments to date (Table 1) are many orders of magnitude smaller than those which will characterise the ocean acidification process driven by slow uptake of anthropogenic CO 2 over many decades. The ocean acidification timescale will be comparable to many thousands of microbial generations, suggesting that evolutionary processes are highly likely to have an influence on system-level responses (Collins and Bell, 2006;Lohbeck et al, 2012;Jin et al, 2013;Reusch and Boyd, 2013). Indeed, culture studies performed to date over longer timescales indicate the potential influence of evolutionary adaptation to increased pCO 2 over modest (< 1.5 yr) periods (Lohbeck et al, 2012;Jin et al, 2013).…”