Haplonttista

Haplonttista refers to a type of life cycle found in some eukaryotic organisms, particularly in certain algae and fungi. In a haplontic life cycle, the dominant and most conspicuous phase of the organism is the haploid (n) stage. This means that the majority of the cells in the organism possess a single set of chromosomes.

The life cycle begins with haploid individuals. Reproduction typically occurs through asexual means, such as mitosis, producing more identical haploid individuals. Sexual reproduction also occurs in the haploid stage, but it involves the fusion of gametes. These gametes are also haploid. When two gametes fuse, they form a diploid (2n) zygote. This zygote is the only diploid stage in the entire life cycle and is usually short-lived.

Following its formation, the diploid zygote undergoes meiosis. Meiosis is a process of cell division that reduces the chromosome number by half, resulting in the production of haploid spores or gametes. These haploid cells then develop into new haploid individuals, thus completing the cycle. The key characteristic of a haplontic life cycle is that meiosis occurs immediately after zygote formation, and the resulting cells are haploid and can develop into new individuals. This contrasts with diplontic life cycles where the diploid stage is dominant, and meiosis produces haploid gametes.