Dataset Information

Contrasting Mixotrophic Lifestyles Reveal Different Ecological Niches in Two Closely Related Marine Protists.

ABSTRACT: Many marine microbial eukaryotes combine photosynthetic with phagotrophic nutrition, but incomplete understanding of such mixotrophic protists, their functional diversity, and underlying physiological mechanisms limits the assessment and modeling of their roles in present and future ocean ecosystems. We developed an experimental system to study responses of mixotrophic protists to availability of living prey and light, and used it to characterize contrasting physiological strategies in two stramenopiles in the genus Ochromonas. We show that oceanic isolate CCMP1393 is an obligate mixotroph, requiring both light and prey as complementary resources. Interdependence of photosynthesis and heterotrophy in CCMP1393 comprises a significant role of mitochondrial respiration in photosynthetic electron transport. In contrast, coastal isolate CCMP2951 is a facultative mixotroph that can substitute photosynthesis by phagotrophy and hence grow purely heterotrophically in darkness. In contrast to CCMP1393, CCMP2951 also exhibits a marked photoprotection response that integrates non-photochemical quenching and mitochondrial respiration as electron sink for photosynthetically produced reducing equivalents. Facultative mixotrophs similar to CCMP2951 might be well adapted to variable environments, while obligate mixotrophs similar to CCMP1393 appear capable of resource efficient growth in oligotrophic ocean environments. Thus, the responses of these phylogenetically close protists to the availability of different resources reveals niche differentiation that influences impacts in food webs and leads to opposing carbon cycle roles.

SUBMITTER: Wilken S

PROVIDER: S-EPMC7065223 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Contrasting Mixotrophic Lifestyles Reveal Different Ecological Niches in Two Closely Related Marine Protists.

Wilken Susanne S Choi Chang Jae CJ Worden Alexandra Z AZ

Journal of phycology 20191101 1

Many marine microbial eukaryotes combine photosynthetic with phagotrophic nutrition, but incomplete understanding of such mixotrophic protists, their functional diversity, and underlying physiological mechanisms limits the assessment and modeling of their roles in present and future ocean ecosystems. We developed an experimental system to study responses of mixotrophic protists to availability of living prey and light, and used it to characterize contrasting physiological strategies in two stram ...[more]

PMID: 31529498

Similar Datasets

Project description:BackgroundPostzygote isolation is an important part of species isolation, especially for fish, and it can be divided into two aspects: genetic isolation and ecological isolation. With the increase in parental genetic distance, the intensity of genetic isolation between them also increases. Will the increase in parental ecological niche differences also lead to the increase in ecological isolation intensity between them? This question is difficult to answer based on the current literature due to the lack of hybridization cases of contrasting ecological niche parents.ResultsCyprinid fish parents (Schizothorax wangchiachii and Percocypris pingi) with contrasting ecological niches (herbivorous and carnivorous) and their F1 hybrids were used as research objects. Fish and periphytic algae were selected as food corresponding to different parental resources. The foraging-related traits of these hybrids are generally the same between parents; however, the intermediate foraging traits of hybrids did not result in intermediate foraging performance for parental resources, and these hybrids could hardly forage for parental resources. The poor foraging performance of these hybrids for parental resources was caused not only by the decline in the foraging ability of these hybrids but, more importantly, by the decrease in foraging activity. Interestingly, these hybrids initially showed a high interest in foraging small fishes; however, after the first successful capture, these hybrids had difficulty ingesting fish and spit them out, which led to the subsequent decrease in foraging activity. We designed a series of experiments to explore the mechanism of the fish spitting of these hybrids, excluding the taste and the size of prey, and found that the decrease in their pharyngeal tooth puncture ability may be the reason.ConclusionsThis study was the first to demonstrate that these parents with contrasting ecological niches will produce great postzygotic ecological isolation for parental resources. The poor foraging performance of these hybrids for parental resources is mainly due to the decrease in foraging activity. Interestingly, these hybrids have obvious fish-spitting behaviour, which is a typical example of the incompatibility between intermediate traits and genetic behaviors.

Project description:Heterotrophic microbes play a key role in remineralizing organic material in the coastal ocean. While there is a significant body of literature examining heterotrophic bacterioplankton and phytoplankton communities, much less is known about the diversity, dynamics, and ecology of eukaryotic heterotrophs. Here, we focus on the Labyrinthulomycetes, a fungus-like protistan group whose biomass can exceed that of the bacterioplankton in coastal waters. We examined their diversity and community structure in a weekly temperate coastal ocean time series. Their seasonal community patterns were related to temperature, insolation, dissolved inorganic carbon, fungal abundance, ammonia, chlorophyll a, pH, and other environmental variables. Similar to the bacterioplankton, annual community patterns of the Labyrinthulomycetes were dominated by a few persistent taxa with summer or winter preferences. However, like the patterns of fungi at this site, the majority of the Labyrinthulomycetes phylotypes occurred mostly as short, reoccurring, season-specific blooms. Furthermore, some specific phylotypes of Labyrinthulomycetes displayed time-lagged correlations or cooccurrences with bacterial, algal, or fungal phylotypes, suggesting their potentially multifaceted involvement in the marine food webs. Overall, this study reports niche partitioning between closely related Labyrinthulomycetes and identifies distinct ecotypes and temporal patterns compared to bacterioplankton and fungi.IMPORTANCE Increasing evidence has shown that heterotrophic microeukaryotes are an important component in global marine ecosystems, while their diversity and ecological functions remain largely unknown. Without appropriately incorporating these organisms into the food web models, our current understanding of marine microbial community ecology is incomplete, which may further hamper broader studies of biogeochemistry and climate change. This study focuses on a major group of unicellular fungus-like protists (Labyrinthulomycetes) and reveals their distinct annual community patterns relative to fungi and bacteria. Results of our observations provide new information on the community structure and ecology of this protistan group and shed light on the intricate ecological roles of unicellular heterotrophic eukaryotes in the coastal oceans.

Dataset Information

Contrasting Mixotrophic Lifestyles Reveal Different Ecological Niches in Two Closely Related Marine Protists.

Publications

Contrasting Mixotrophic Lifestyles Reveal Different Ecological Niches in Two Closely Related Marine Protists.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets