CC BY
27
88 • "PROTIST—2016
been used as indicators of freshwater quality, they are rarely used in this capacity in marine waters. Here I will summarize the results of a series of studies carried out in Jiaozhou Bay, on the Yellow Sea coast of NE China, in which we investigate the relationships between ciliate communities, both planktonic and periphytic, and certain physico-chemical parameters that varied at different sites within the Bay. In each study, ciliates were identified and enumerated by direct microscopy, and data were analyzed using various statistical packages mainly within PRIMER. A main aim of this investigation was to develop protocols that maximize the efficiency of sampling and analyses of the ciliate communities. Our main findings were: (1) the 8-sampling events per year may be an optimal sampling strategy for planktonic ciliated protozoan seasonal research in marine ecosystems; (2) 90% of the periphytic community could be recovered on 10 microscope slide replicates immersed at one depth for 3 — 21 days; (3) multivariate (step-best-matching) analysis allows a subset of the most reliable indicator species to be identified without losing accuracy of water quality prediction; (4) applying taxonomic efficiency, i.e., identifying to the highest rank without losing critical bioindicator information, revealed that genus-level identification allows for accurate prediction of water quality; (5) efficiencies of sample analyses can be achieved by omitting ubiquitous groups, and using presence/ absence of others rather than abundance data.
SPECIES CLASSIFICATION AND MATING IN FORAMINIFERA
Weiner A.K.M., Tsuchiya M., Toyofuku T., Kitazato H.
JAMSTEC, Japan Agency for Marine Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Kanagawa, Japan aweiner@jamstec.go.jp
Many groups of foraminifera are characterized by the formation of elaborate shells, which provide detailed morphological features, useful for species classification. Since the majority of works focuses on their fossilized shells, a comprehensive morphotaxonomy has been established. Yet, genetic analyses revealed an even higher diversity on the molecular level, hidden within the traditional morphospecies. These cryptic species are marked by large genetic distances and differentiated distribution patterns, implying that cryptic species rather than morphospecies represent the level of species. As a consequence, today we are facing a conflict between the morphological species concept and the interpretation of genetic diversity. The
biological meaning of both is still unclear and the relationship between genetic divergence and the level of species or populations remains uncertain. In order to overcome this conflict, we try to combine aspects of morphological variability, genetic diversity and reproduction to achieve an integrative approach for species delimitation in foraminifera. To this end, we carry out breeding experiments on benthic foraminifera to observe the mating behavior between genetically divergent lineages to detect the level of divergence that corresponds to reproductive isolation. In addition, we plan to observe the mating behavior among genetically homogenous populations to examine the existence of different mating types within a population. The mating system largely influences the generation of genetic variation and contributes to the process of adaptation. Understanding its mechanisms in foraminifera is thus essential to understand the diversification and evolution of the group.
THE EVOLUTION OF MITOCHONDRIAL MEMBRANE CONTACT SITES Wideman J.G.
Department ofBiosciences, University ofExeter, United Kingdom
jeremy.grant.wideman@gmail.com It is commonly accepted that mitochondria evolved from an alpha-proteobacterial endosymbiont to become the major energy producing organelle of the eukaryote cell. Accounts describing the integration of the pre-mitochondrial symbiont into host cell processes often focus on this transfer of the control of energy production from the symbiont to the host. However, mitochondria are more than mere ATP generators and have several physical and functional links to various cell systems. One such link is manifested in the physical and functional link between mitochondria and the endomembrane system in the form of membrane contact sites (MCSs). These MCSs are important for non-vesicular lipid transport between apposed membranes. Recent progress has identified the protein complexes responsible for maintaining MCSs in Saccharomyces cerevisiae. A surprising number of functionally overlapping mitochondrial MCS tethering complexes have been described, but the extent to which MCS tethers are conserved between distant lineages appears to vary. Thus, while being functionally redundant in S. cerevisiae, MCSs appear to have a high degree of evolutionary plasticity in eukaryotes. Taken together, these data suggest that the last eukaryote common ancestor had a mitochondrion highly connected to diverse endomembranes, but over the course of eukaryote
