The genus Cyclops (Copepoda, Cyclopoida) in Europe

Abstract

Kraj ı cek, M., Fott, J., Miracle, M.R., Ventura, M., Sommaruga, R., Kirschner, P., Cern y, M. (2015). The genus Cyclops (Copepoda, Cyclopoida) in Europe. -Zoologica Scripta, 45, 671-682. Although copepods of the genus Cyclops are among the most common and dominant plankton taxa of lakes in the northern temperate zone, their taxonomy is still unclear. We analysed an extensive array of Cyclops populations from Europe by means of molecular methods and evaluated morphological characters. Altogether, 68 populations of Cyclops species were sampled, assigned to morphospecies and sequenced for the 12S rRNA gene. Selected populations of each morphospecies were additionally sequenced for three mitochondrial (16S rRNA, cytochrome b, COI) and two nuclear genes (18S rRNA, ITS1) and analysed for micromorphological traits. Our analysis revealed fifteen lineages that can be regarded as separate species. Thirteen of these match currently accepted species, while the remaining two lineages were distinct from the other described species. Thus, their taxonomic status is open to further studies. Besides taxonomy, our study gives new insights into the ecology, distribution and phylogenetic relationships of these species. Finally, a set of morphological traits was selected to facilitate identification.

Towards a phylogeny ofCyclops(Copepoda): (in)congruences among morphology, molecules and zoogeography

“…Since the 1980s, it has become standard in copepod taxonomy to include the “microcharacters” (spinule ornamentation of the limbs, seta setulation, integumental pore signature) along with the classic gross characters (limb segmentation, body proportions). Interestingly, these fine structures frequently show less intraspecific variation than the morphometric characters and correlate well with other (gross) morphological features, molecular markers and the presence of reproductive isolation (Baribwegure & Dumont, ; Fiers & Van de Velde, ; Karaytug, ; Krajíček et al, ; Van de Velde, ). The utility of some surface ornamentation characters for species diagnoses has been explored in the genus Cyclops as well (Einsle, ; Hołyńska, ; Hołyńska & Dahms, ; Hołyńska & Dimante‐Deimantovica, ).…”

“…Y, ” C. mauritaniae , C. divergens , C. bohater and C. lacustris (Table , Figures , a, b) , and also support sister relationships between the divergens ‐ and abyssorum ‐clade. The “unscaled” trees show the divergens ‐group paraphyletic and C. lacustris and C. bohater as basal offshoots of the genus (Supporting information Figure ), yet such a topology is not supported by either the “unordered” and “scaled” reconstructions, nor the phylogeny inferred from molecular characters (Krajíček et al, ). The divergens ‐clade is characterized by the occurrence of the 7‐setae state on the second endopodal segment of the antenna in the male (with the exception of C. lacustris in which 8 setae are present), and the pilose medial expansion of the P4 basipodite (fixed in Cyclops sp.…”

“…The first phylogenetic analysis of Cyclops , conducted by Krajíček et al (), used partial nuclear (18S rRNA) and mitochondrial (12S rRNA, 16S rRNA, cytochrome b and cytochrome c oxidase I) genes and the nuclear internal transcribed spacer region 1, and addressed the evolutionary relationships within the European (14) species. Their results showed a close correspondence between lineages defined by the genetic markers and morphospecies defined by microcharacters, and also supported conspecificity of widely separated populations of the boreo/arctic‐alpine Cyclops abyssorum .…”

“…Their results showed a close correspondence between lineages defined by the genetic markers and morphospecies defined by microcharacters, and also supported conspecificity of widely separated populations of the boreo/arctic‐alpine Cyclops abyssorum . Due to the lack of fossil calibration points, Krajíček et al () used the “standard evolutionary rate for crustacean mitochondrial DNA” and estimated a Middle‐ to latest Miocene divergence of the basal clades in the European Cyclops. Radiation of the basal lineages was suggested to have coincided with the Late Miocene climate cooling and the onset of drying in the mid‐latitude continental interior of Eurasia (Krajíček et al, ; Popova, Utescher, Gromyko, Bruch, & Mosbrugger, ).…”

“…Supplementing the morphological analyses are phylogenetic reconstructions utilizing molecular characters (partial nuclear 18S and 28S ribosomal genes, mitochondrial cytochrome oxidase I and complete internal transcribed spacer regions I and II), albeit with considerably limited taxon sampling. These markers were selected for their ability to provide valuable phylogenetic information based on previous investigations of cyclopoid systematics (Krajíček et al, ; Mayor, Galimova, Sheveleva, Sukhanova, & Kirilchik, ; Mayor, Sheveleva, Sukhanova, Timoshkin, & Kiril'chik, ; Wyngaard et al, ; Wyngaard, Rocha, & Pepato, ; Zagoskin, Lazareva, Grishanin, & Mukha, ). The molecular characters are used in combination with morphology, and alone, laying the foundation for the first such study that examines congruences and incongruences between the morphological and molecular data sets in a phylogenetic analysis of a cyclopid genus.…”