CC BY
29
Protistology ■ 85
sampling depth on the performance of a transfer function using an independent test-set from four Sphagnum-dominated sites in European Russia (Penza Region). We focus on transfer function performance along localised hydrological gradients, which is a useful analogue for predictive ability through time. The performance of the transfer function with the independent test-set was generally weaker than for the leave-one-out or bootstrap cross-validations. However, the transfer function was robust for the reconstruction of relative changes in water-table depth, provided the presence ofgood modern analogues and overlap in water-table depth ranges. When applied to subsurface samples, the performance of the transfer function was reduced due to selective decomposition, the presence of deep-dwelling taxa or vertical transfer of shells. Our results stress the importance of thorough testing of transfer functions, and highlight the role of taphonomic processes in determining results. Further studies of stratification, taxonomy and taphonomy of testate amoebae will be needed to improve the robustness of transfer function output. This research was funded by the Russian Scientific Fund (grant 14-14-00891) and grant ofthe President of Russian Federation (MD-7930.2016.4).
CELL COAT EVOLUTION AND PHYLOGENY OF DACTYLOPODID AMOEBAE (AMOE-BOZOA, DISCOSEA) Udalov Ilya A.
DepartmentofInvertebrate Zoology, Faculty ofBiology, Saint-Petersburg State University, Universitetskaya nab. 7/9,199034 St. Petersburg, Russia [email protected]
An amoebae order Dactylopodida was established on the base ofthe results of the molecular phylogenetic analysis. To date it includes genera Vexillifera, Cunea, Pseudoparamoeba, Korotnevella, Paramoeba and Neoparamoeba. All representatives of this order share the ability to form non-furcating finger-shaped subpseudopodia (dactylopodia), which considered as morphological synapomorphy for this group. Up to now all these genera were distinguished by morhological features: peculiarities of locomotive form, presence or absence of kinetoplastid endo-symbiont (Perkinsela amoebae-like organism, or PLO) and structure ofthe cell coat. The details ofthe cell coat evolution in Dactylopodida are still unclear. Recent studies shown that situation with generic distinctions in this group actually is much more complex. One of the studied species formally fits the diagnosis of the genus Korotnevella, because it has scales and lacks PLO. At the same time its
18S rRNA gene sequence robustly groups with Pseudoparamoeba pagei (which lacks both PLO and scales) and never branches among those of Korotnevella spp. Thus the situation described above shows that to the moment the boundary between two genera Pseudoparamoeba and Korotnevella can be correctly drawn only on the basis of 18S rDNA sequence. Our data probably mean that actually the presence of scales is a primitive feature for a whole clade, which unifies genera Pseudoparamoeba, Korotnevella, Paramoeba and Neoparamoeba. Within this group scales retained in some species and lost in others.
ECOLOGICAL STUDY OF THRAUSTOCHY-TRIDS (LABYRINTHULEA, STRAMENO-PILES)
Ueda M.12, Doi K.12, Nomura Y.3, Nakajima M.4, Honda D.32
1 - Graduate School of Natural Science, Konan University, Japan
2 - Institute for Integrative Neurobiology, Konan University, Japan
3 - Faculty of Science and Engineering, Konan University, Japan
4 - Research Institute ofEnvironment, Agriculture and Fisheries, Osaka Prefecture, Japan [email protected]
Thraustochytrids have been recognized as important decomposers in the marine ecosystem. However, in many cases, this recognition is based on the short investigation of the biomass of whole thraustochytrids without distinguishing the species. In this study, we investigated the seasonal changes of biomass and species composition ofthraustochytrids by continuous monitoring at river mouths and coastal areas in Japan for five years. Remarkable peaks of cell numbers of the thraustochytrids were observed in early summer and/or summer at the river mouths. This phenomenon was named "thraustochytrid spikes". Thraustochytrid biomass didn't correlate with chlorophyll a, but it seemed that the peaks occurred after the decrease in salinity. This phenomenon probably suggested that the thraustochytrid biomass is affected by the supply of the terrestrial organic matter from river water. Although thraustochytrid biomass was only 1.59% that of bacterial biomass, the fixed energy (as biomass) transferred directly from thraustochytrids to zooplankton was estimated to be 15.9% of that transferred from bacterioplankton via phagotrophic protists. Moreover, a clear seasonal succession of thraustochytrid species was repeatedly observed every year. However, species composition differs
