The effect of variation in developmental mode on the population dynamics of a spionid polychaete (Pygospio elegans) in a heterogeneous environment

A new haemocyanin in cuttlefish (Sepia officinalis) eggs: sequence analysis and relevance during ontogeny

Abstract Background Haemocyanin is the respiratory protein of most of the Mollusca. In cephalopods and gastropods at least two distinct isoforms are differentially expressed. However, their physiological purpose is unknown. For the common cuttlefish Sepia officinalis, three isoforms are known so far, whereas for only two of them the complete mRNA sequences are available. In this study, we sequenced the complete mRNA of the third haemocyanin isoform and measured the relative expression of all three isoforms during embryogenesis to reveal a potential ontogenetic relevance. Results The cDNA of isoform 3 clearly correlates to the known Sepia officinalis haemocyanin subunits consisting of eight …

Droplet digital PCR as a tool for investigating dynamics of cryptic symbionts

Abstract Interactions among symbiotic organisms and their hosts are major drivers of ecological and evolutionary processes. Monitoring the infection patterns among natural populations and identifying factors affecting these interactions are critical for understanding symbiont–host relationships. However, many of these interactions remain understudied since the knowledge about the symbiont species is lacking, which hinders the development of appropriate tools. In this study, we developed a digital droplet PCR (ddPCR) assay based on apicomplexan COX1 gene to detect an undescribed agamococcidian symbiont. We show that the method gives precise and reproducible results and enables detecting cryp…

Seasonal variation in diversity of marine benthic invertebrates leads to a positive species-genetic diversity correlation (SGDC)

Species-genetic diversity correlations (SGDCs) are useful indicators of processes that simultaneously affect diversity at multiple biological levels. We combined spatial and temporal sampling of 4 study sites in the Danish Isefjord-Roskilde Fjord Estuary at 4 time points over 1 yr to investigate the effect of seasonal variation on SGDCs. Species diversity was estimated as species richness from samples comprising 20752 individuals representing 51 benthic invertebrate taxa. Genetic diversity was estimated for a single focal taxon, the polychaete Pygospio elegans, as mean allelic richness at 7 microsatellite loci. Combining all samples, a significant positive correlation between species richne…

Seasonal genetic variation associated with population dynamics of a poecilogonous polychaete worm

Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegans at four sites in the Danish Isefjord‐Roskilde‐Fjord estuary at six time points, from March 2014 until February 2015. We found genetic differentiation between our sampling sites as well as seasonal differentiation at two of the sites. The seasonal genetic shift correlated with the appearance of new s…

Population and reproductive dynamics of the polychaete Pygospio elegans in a boreal estuary complex

Pygospio elegans is an opportunistic, wide-spread spionid polychaete that reproduces asexually via fragmentation and can produce benthic and pelagic larvae, hence combining different developmental modes in one species. We documented the density, size distribution, and reproductive activity of P. elegans at four sites in the Danish Isefjord-Roskilde Fjord estuary complex, where all modes of reproduction were reported. We compared population dynamics of this species to environmental parameters such as salinity, temperature, and sediment characteristics (grain size, sorting, porosity, water content, organic content, C/N). We observed that new cohorts—resulting either from sexual or asexual rep…

Acute and chronic response to a change in salinity of the euryhaline polychaete Pygospio elegans (Claparède)

Abstract Estuaries are thought to be very harsh environments because their physico-chemical parameters, such as salinity, temperature and oxygen, can fluctuate substantially. The distribution of species living in an estuary is largely determined by how well they can cope with such fluctuations. The spionid polychaete Pygospio elegans is common in boreal estuarine habitats that show strong salinity fluctuations, living in habitats ranging from fully marine salinities to brackish environments with salinities as low as 5. In this study we investigated the abilities of P. elegans to cope with an acute as well as a long-term change in salinity. Specimens originating from a salinity of about 15 w…

Data from: Seasonal genetic variation associated with population dynamics of a poecilogonous polychaete worm

Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegans at four sites in the Danish Isefjord-Roskilde-Fjord estuary at six time points, from March 2014 until February 2015. We found genetic differentiation between our sampling sites as well as seasonal differentiation at two of the sites. The seasonal genetic shift correlated with the appearance of new s…