Dataset Information

A case of nascent speciation: unique polymorphism of gonophores within hydrozoan Sarsia lovenii.

ABSTRACT: Revealing the mechanisms of life cycle changes is critical for understanding the processes driving hydrozoan evolution. Our analysis of mitochondrial (COI, 16S) and nuclear (ITS1 and ITS2) gene fragments resulted in the discovery of unique polymorphism in the life cycle of Sarsia lovenii from the White Sea. This polymorphic species exhibits two types of gonophores: hydroids produce both free-swimming medusae and attached medusoids (phenotypic polymorphism). Our phylogenetic analysis revealed the intrinsic genetic structure of S. lovenii (genetic polymorphism). Two haplogroups inhabiting the White Sea differ in their reproductive modes. Haplogroup 1 produces attached medusoids, and haplogroup 2 produces free-swimming medusae. Our experiments indicated the possibility of free interbreeding between haplogroups that likely is a rare event in the sea. We propose that inter-haplogroup crossing of S. lovenii in the White Sea may be limited by discordance in periods of spawning or by spatial differences in habitat of spawning specimens. Our finding can be interpreted as a case of nascent speciation that illustrates the patterns of repeated medusa loss in hydrozoan evolution. Life cycle traits of S. lovenii may be useful for elucidating the molecular mechanisms of medusa reduction in hydrozoans.

SUBMITTER: Prudkovsky AA

PROVIDER: S-EPMC6820802 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A case of nascent speciation: unique polymorphism of gonophores within hydrozoan Sarsia lovenii.

Prudkovsky Andrey A AA Ekimova Irina A IA Neretina Tatiana V TV

Scientific reports 20191029 1

Revealing the mechanisms of life cycle changes is critical for understanding the processes driving hydrozoan evolution. Our analysis of mitochondrial (COI, 16S) and nuclear (ITS1 and ITS2) gene fragments resulted in the discovery of unique polymorphism in the life cycle of Sarsia lovenii from the White Sea. This polymorphic species exhibits two types of gonophores: hydroids produce both free-swimming medusae and attached medusoids (phenotypic polymorphism). Our phylogenetic analysis revealed the ...[more]

PMID: 31664107

Similar Datasets

Project description:Background: The Dobzhansky-Muller (D-M) model of speciation by genic incompatibility is widely accepted as the primary cause of interspecific postzygotic isolation. Since the introduction of this model, there have been theoretical and experimental data supporting the existence of such incompatibilities. However, speciation genes have been largely elusive, with only a handful of candidate genes identified in a few organisms. The Saccharomyces sensu stricto yeasts have small genomes, can be easily cultured, and can mate interspecifically to produce sterile hybrids, are thus an ideal model for studying postzygotic isolation. Among them, only a single D-M pair has been found, between S. bayanus and S. cerevisiae, comprising the mitochondrially targeted product of a nuclear gene, AEP2, and a mitochondrially encoded locus, OLI1, the 5' region of whose transcript is bound by Aep2. Thus far, no D-M pair of nuclear genes has been identified between any sensu stricto yeasts. Methods: We report here the first detailed genome-wide analysis of rare F2 progeny from an otherwise sterile hybrid, and show that no classic D-M pairs of speciation genes exist between the nuclear genomes of the closely related yeasts S. cerevisiae and S. paradoxus. Instead, our analyses suggest that more complex interactions may be responsible for their post-zygotic separation. These interactions most likely involve multiple loci having weak effects, as there were multiple significant pairwise combinations of loci, with no single combination being completely excluded from the viable F2s. Conclusions: The lack of a nuclear encoded classic D-M pair between these two yeasts, yet the existence of multiple loci that may each exert a small effect through complex interactions, suggests that initial speciation events might not always be mediated by D-M pairs. An alternative explanation may be that "death by a thousand cuts" leads to speciation, whereby an accumulation of polymorphisms can lead to an incompatibility between the species "transcriptional and metabolic networks, with no single pair at least initially being responsible for the incompatibility. After such a speciation event, it is possible that one or more D-M pairs might subsequently arise following isolation. Genotypes for hybrids between S. cerevisiae and S. paradoxus. A genotyping experiment design type classifies an individual or group of individuals on the basis of alleles, haplotypes, SNP's.

Project description:UnlabelledA large amount of bacterial biomass is transferred from land to ocean annually. Most transferred bacteria should not survive, but undoubtedly some do. It is unclear what mechanisms these bacteria use in order to survive and even thrive in a new marine environment. Myroides profundi D25(T), a member of the Bacteroidetes phylum, was isolated from deep-sea sediment of the southern Okinawa Trough near the China mainland and had high genomic sequence identity to and synteny with the human opportunistic pathogen Myroides odoratimimus. Phylogenetic and physiological analyses suggested that M. profundi recently transitioned from land to the ocean. This provided an opportunity to explore how a bacterial genome evolved to survive in a novel environment. Changes in the transcriptome were evaluated when both species were cultured under low-salinity conditions and then transferred to high-salinity conditions. Comparative genomic and transcriptomic analyses showed that M. profundi altered transcription regulation in the early stages of survival. In these stages, vertically inherited genes played a key role in the survival of M. profundi. The contribution of M. profundi unique genes, some possibly acquired by horizontal gene transfer (HGT), appeared relatively small, and expression levels of unique genes were diminished under the high-salinity conditions. We postulate that HGT genes might play an important role in longer-term adaptation. These results suggested that some human pathogens might have the ability to survive in and adapt to the marine environment, which may have important implications for public health control in coastal regions.ImportanceHorizontal gene transfer (HGT) is considered to be important for bacteria to adapt to a different microhabitat. However, our results showed that vertically inherited genes might play more important roles than HGT genes in the nascent adaptation to the marine environment in the bacterium Myroides profundi, which has recently been transferred from land to ocean. M. profundi unique genes had low expression levels and were less regulated under high-salinity conditions, indicating that the contribution of HGT genes to survival of this bacterium under marine high-salinity conditions was limited. In the early adaptation stages, M. profundi apparently survived and adapted mainly by regulating the expression of inherited core genes. These results may explain in part why human pathogens can easily be detected in marine environments.

Dataset Information

A case of nascent speciation: unique polymorphism of gonophores within hydrozoan Sarsia lovenii.

Publications

A case of nascent speciation: unique polymorphism of gonophores within hydrozoan Sarsia lovenii.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets