Project: Impacts of Evolution on the Response of Phytoplankton Populations to Rising CO2

Acronym/Short Name:P-ExpEv
Project Duration:2013-06 - 2019-05
Geolocation:Experiment housed in laboratories at Michigan State University

Description

Note: This project is also affiliated with the NSF BEACON Center for the Study of Evolution in Action.

Project Description from NSF Award:
Human activities are driving up atmospheric carbon dioxide concentrations at an unprecedented rate, perturbing the ocean's carbonate buffering system, lowering oceanic pH, and changing the concentration and composition of dissolved inorganic carbon. Recent studies have shown that this ocean acidification has many short-term effects on phytoplankton, including changes in carbon fixation among others. These physiological changes could have profound effects on phytoplankton metabolism and community structure, with concomitant effects on Earth's carbon cycle and, hence, global climate. However, extrapolation of present understanding to the field are complicated by the possibility that natural populations might evolve in response to their changing environments, leading to different outcomes than those predicted from short-term studies. Indeed, evolution experiments demonstrate that microbes are often able to rapidly adapt to changes in the environment, and that beneficial mutations are capable of sweeping large populations on time scales relevant to predictions of environmental dynamics in the coming decades. This project addresses two major areas of uncertainty for phytoplankton populations with the following questions:
1) What adaptive mutations to elevated CO2 are easily accessible to extant species, how often do they arise, and how large are their effects on fitness?
2) How will physical and ecological interactions affect the expansion of those mutations into standing populations?

This study will address these questions by coupling experimental evolution with computational modeling of ocean biogeochemical cycles. First, cultured unicellular phytoplankton, representative of major functional groups (e.g. cyanobacteria, diatoms, coccolithophores), will be evolved under simulated year 2100 CO2 concentrations. From these experiments, estimates will be made of a) the rate of beneficial mutations, b) the magnitude of fitness gains conferred by these mutations, and c) secondary phenotypes (i.e., trade-offs) associated with these mutations, assayed using both physiological and genetic approaches. Second, an existing numerical model of the global ocean system will be modified to a) simulate the effects of changing atmospheric CO2 concentrations on ocean chemistry, and b) allow the introduction of CO2-specific adaptive mutants into the extant populations of virtual phytoplankton. The model will be used to explore the ecological and biogeochemical impacts of beneficial mutations in realistic environmental situations (e.g. resource availability, predation, etc.). Initially, the model will be applied to idealized sensitivity studies; then, as experimental results become available, the implications of the specific beneficial mutations observed in our experiments will be explored.

This interdisciplinary study will provide novel, transformative understanding of the extent to which evolutionary processes influence phytoplankton diversity, physiological ecology, and carbon cycling in the near-future ocean. One of many important outcomes will be the development and testing of nearly-neutral genetic markers useful for competition studies in major phytoplankton functional groups, which has applications well beyond the current proposal.


DatasetLatest Version DateCurrent State
Data and analysis code used to experimentally evolve representatives of four phytoplankton functional types in co-culture with a heterotrophic bacterium under either present-day or predicted future pCO2 conditions2024-04-25Final no updates expected
Data and code from an examination of growth rates of cyanobacteria co-cultured with a heterotrophic bacterium, Alteromonas, under either present-day or predicted future pCO2 conditions2024-04-24Final no updates expected
Data on laboratory cultures and statistical analysis code associated with the paper "Co-culture with Synechococcus facilitates the growth of Prochlorococcus under ocean acidification conditions" published in Environmental Microbiology2021-02-05Final no updates expected
NCBI accessions of the harmful alga Heterosigma akashiwo (CCMP2393) grown under a range of CO2 concentrations from 200-1000 ppm2018-10-11Final no updates expected
Accessions for clones of heterotrophic "helper" bacterium Alteromonas EZ55 grown at elevated and ambient CO2.2018-05-09Final no updates expected
Clones of Prochlorococcus MIT9312 mixed with clonal isolates of the heterotrophic "helper" bacterium Alteromonas EZ55 (P-ExpEv project)2017-04-24Final no updates expected
Eukaryote transcriptome assemblies and associated metadata available on iMicrobe (P-ExpEv project)2016-05-20Final no updates expected
Literature review of Ocean Acidification (OA) effects on phytoplankton (P-ExpEv project)2015-07-07Final with updates expected

People

Lead Principal Investigator: James Jeffrey Morris
University of Alabama at Birmingham (UA/Birmingham)

Co-Principal Investigator: Sonya T. Dyhrman
Lamont-Doherty Earth Observatory (LDEO)

Co-Principal Investigator: Michael J. Follows
Massachusetts Institute of Technology (MIT-EAPS)

Co-Principal Investigator: Richard E Lenski
Michigan State University (MSU)


Programs

Science, Engineering and Education for Sustainability NSF-Wide Investment (SEES): Ocean Acidification (formerly CRI-OA) [SEES-OA]