The haplo-diplontic life cycle expands niche space of coccolithophores

Abstract

Abstract. Coccolithophores are globally important marine calcifying phytoplankton that utilize a haplo-diplontic life cycle. The haplo-diplontic life cycle allows coccolithophores to divide in both life cycle phases, and has been proposed to allow coccolithophores to expand their niche space. To-date research has however largely overlooked the life cycle of coccolithophores, and has instead focused on the diploid life cycle phase. Through a synthesis of global scanning electron microscopy (SEM) coccolithophore abundance data (n = 2534), we show that the haploid life cycle phase contributes significantly to coccolithophore abundance, constituting ≈18 % of species abundance for which haploid-diploid pairs are defined. Using hypervolumes to quantify the niche space of coccolithophores, we furthermore show that the haploid and diploid life cycle phases inhabit contrasting niches, and that this allows coccolithophores to expand their niche space by ≈17 %. Our results highlight that future coccolithophore research should consider both life cycle stages, as omission of the haploid life cycle phase in current research limits our understanding of coccolithophore ecology.

Haplotype-aware multiomics unveils the regulatory basis of haplodiplontic life-cycle differentiation in a cosmopolitan marine alga

“…While animals typically have diplontic life cycles with haploid genomes restricted to gametes, land plants, various algae, and other eukaryotes are characterized by haplodiplontic life cycles, where both diploid and haploid cells can divide by mitosis, express distinct attributes, and form independent populations in microbial species (3). The differentiation in morphological and physiological attributes between life-cycle phases in haplodiplontic life cycles expands the functional scope of these eukaryotes, where diploid and haploid organisms can explore different niches and display distinct life strategies (4,5).…”

“…Coccolithophores are haplodiplontic, calcifying microalgae that are highly abundant and ecologically significant across global oceans (4)(5)(6)(7). They contribute around 10% to global primary production as a major drive of the biological carbon pump (8).…”