Diplontista

Diplontista is a group of single-celled eukaryotes that exhibit a diplontic life cycle. In this type of life cycle, the only haploid phase is represented by the gametes. The vegetative cells of a diplontic organism are diploid, meaning they contain two complete sets of chromosomes. Meiosis occurs during gamete formation, reducing the chromosome number by half. Fertilization then restores the diploid state when two gametes fuse.

Key characteristics of diplontista include their unicellular nature and the dominance of the diploid stage. This is in contrast to haplontic organisms, where the haploid stage is dominant, and alternations of generations, where both haploid and diploid multicellular stages exist. Examples of organisms with a diplontic life cycle can be found across various eukaryotic lineages, though the term "diplontista" specifically refers to a proposed clade encompassing certain protists.

Research into diplontista often focuses on understanding the genetic and cellular mechanisms that regulate their life cycle, particularly the precise timing and control of meiosis and gametogenesis. The study of these organisms contributes to our broader understanding of eukaryotic evolution and the diversity of reproductive strategies found in nature.