Did Terrestrial Diversification of Amoebas (Amoebozoa) Occur in Synchrony with Land Plants?

Abstract

Evolution of lineage diversification through time is an active area of research where much progress has been made in the last decade. Contrary to the situation in animals and plants little is known about how diversification rates have evolved in most major groups of protist. This is mainly due to uncertainty about phylogenetic relationships, scarcity of the protist fossil record and the unknown diversity within these lineages. We have analyzed the evolutionary history of the supergroup Amoebozoa over the last 1000 million years using molecular dating and species number estimates. After an origin in the marine environment we have dated the colonization of terrestrial habitats by three distinct lineages of Amoebozoa: Dictyostelia, Myxogastria and Arcellinida. The common ancestor of the two sister taxa, Dictyostelia and Myxogastria, appears to have existed before the colonization of land by plants. In contrast Arcellinida seems to have diversify in synchrony with land plant radiation, and more specifically with that of mosses. Detection of acceleration of diversification rates in Myxogastria and Arcellinida points to a co-evolution within the terrestrial habitats, where land plants and the amoebozoans may have interacted during the evolution of these new ecosystems.

Novel Diversity of Deeply Branching Holomycota and Unicellular Holozoans Revealed by Metabarcoding in Middle Paraná River, Argentina

“…This is also in agreement with previous studies that found a large undetected diversity within this lineage, and highlights the importance of unraveling it to understand its evolution (Romeralo et al, 2011;Fiz-Palacios et al, 2013;Tekle et al, 2016;Kang et al, 2017).…”

Testate Amoebae in the 407-Million-Year-Old Rhynie Chert

“…Of course, without fossil calibration points, the error bars in these molecular clocks are necessarily large. That said, the clock estimates of Fiz-Palacios et al [39] and Lahr et al [40] are consistent with the hypothesis that terrestrial arcellinids, diversified as land plants, began to transform terrestrial ecosystems. The position of Leptochlamys within arcellinid phylogeny remains uncertain, as it has not been sequenced and so is absent from modern molecular analyses.…”

Atypical ploidy cycles, Spo11, and the evolution of meiosis

“…Spo11 will doubtless be found to have been lost in a number of lineages, perhaps most frequently in newly asexual lineages. In the social amoeba, the genera Dictyostelium, Polysphondylium, and Acytostelium, Spo11 appears to have already been absent in their most recent common ancestor [17] (and unpublished results), which is thought to have lived several hundred million years ago [58]. This is noteworthy because these organisms are believed to be sexual [59].…”