Statoblast ultrastructure and genetic identity ofPectinatella magnificapopulation, based on COI gene, from three different watersheds in Korea

Abstract

Pectinatella magnifica, one of the most common freshwater bryozoans in the world, is an indicator species of eutrophic waters. This species was a major source of concern in 2014 in Korea due to uncertainty surrounding its toxicity to humans and the aquatic biota. Few studies of its morphology and of its physiological characteristics have been conducted in Korea. To investigate the ultrastructural features and molecular phylogeny of P. magnifica, we used scanning electron microscopy (SEM) analysis and the molecular approach with mitochondrial cytochrome c oxidase subunit I gene (COI) sequence data from 20 colonies in three watersheds. Our morphological analysis of colonies and statoblasts indicates that this species has distinct taxonomic features, including a couple of white spots on the lophophora, a red pigmented mouth, and multiple statoblasts bearing hooked spines. The ultrastructure of the statoblasts, including the annular surface features, pore morphology, and inner chamber distribution, was confirmed using SEM. All of the newly generated P. magnifica COI sequences were identical to one another, regardless of geographic location. The application of a maximum likelihood analysis showed the phylogenetic position and the sister relation with Cristatella mucedo. The results of this molecular analysis of P. magnifica in Korea using a barcode gene provide a means to reliably classify this species. This study, which is the first of its kind, also contains detailed information on the morphology and phylogenetic relationships of P. magnifica.

AFLP reveals low genetic diversity of the bryozoan Pectinatella magnifica (Leidy, 1851) in the Czech Republic

“…The colonies are covered on their surface with rosettes, each containing 12–18 genetically identical zooids and can lead to considerable dimension and weight, as in the case of nearly 1 m diameter and 70 kg colony described by Balounová et al [ 7 ]. Recent studies have focused on the determination of evolutionary relationships within P. magnifica , incorporating morphological traits (such as the morphology of the statoblasts, white spots on lophophora, pigmented mouth), molecular approaches, or a combination of both morphological traits and genetic data [ 8 ]. Most systematic (phylogenetic) studies including P. magnifica have used nuclear ribosomal ( ssrDNA, lsrDNA ) and mitochondrial ( rrnL, rrnS, cox1, cox3, cytb ) genes [ 9 – 13 ].…”

“…Most systematic (phylogenetic) studies including P. magnifica have used nuclear ribosomal ( ssrDNA, lsrDNA ) and mitochondrial ( rrnL, rrnS, cox1, cox3, cytb ) genes [ 9 – 13 ]. However, to determine intraspecific relatedness, ribosomal and mitochondrial genes are not sufficient, as demonstrated for instance in the case of using mitochondrial cytochrome c oxidase subunit I gene ( cox1 ) for intraspecific analysis of geographically distinct colonies of P. magnifica in Korea [ 8 ]. AFLP markers are considered as one of the most popular tools for genetic analysis in the fields of evolutionary genetics, ecology and conservation of genetic resources [ 14 ].…”

“…Recent studies show that the level of expansion of the non-native Pectinatella magnifica is increasing not only in Europe and Asia, but also within the country of its native origin [ 2 , 4 , 5 , 8 , 20 ]. The AFLP technique is very popular in population and evolutionary genetic studies of organisms with no prior sequence knowledge, aiming to assess the degree of variability and genetic structure among tested individuals.…”

“…Also, STRUCTURE results support the hypothesis that a single metapopulation exists without any significant genetic differentiation. In the study of Kang and An [ 8 ], the comparison of 20 sequences of the cox1 gene from P. magnifica colonies collected from three different watersheds in Korea did not show any variation between the colonies. Low genetic diversity was also observed in other plant and animal invaders, including species which utilize both, sexual and asexual reproduction [ 21 – 24 ].…”

Influence of Weir Construction on Chemical Water Quality, Physical Habitat, and Biological Integrity of Fish in the Geum River, South Korea

“…Under the current conditions, the river bed structure and functions have been affected by habitat simplification and hypoxia at the bottom of the system [10]. At the Sejong Weir, biological health has degraded rapidly due to the dominance of exotic species [11], habitat simplification due to silt accumulation [12], and increased frequency of fish kills.…”