The malate dehydrogenase locus (MDH-A*) has been used to genetically identify Redfish species at the individual level and to determine the probability distribution of soft anal fin ray (AFR) counts which are used to estimate species compositions at the catch level. However, both species are morphologically similar and have been identified as "Sebastes spp." in both stock assessments until 2010 and in the fishery. Lawrence (Unit 1) and Laurentian Channel (Unit 2): Sebastes mentella and S. Two species of Redfish are present in the Gulf of St. This dynamic appeared to favour eventual reversion to diploid-only populations as a result either of diploids out-performing triploids, or of triploids out-performing diploids and crashing in the absence of diploid sperm.
Genetically varied invaders of initially large group size increased their representation by more than those of initially small size in contrast, genetically uniform invaders of large group size diminished on average by more than those of small size, supporting the hypothesis that larger genetically varied groups, with greater genetic variation, had greater competitive advantage than smaller groups with less genetic variation.
Further laboratory experiments instigated invasions by small and large groups of genetically varied Daphnia obtusa into large genetically uniform populations of the same species, and vice versa. This small competitive release was predicted to be sufficient for immediate coexistence of sexual and asexual populations of Daphnia pulex. Genetically varied populations had significantly higher birth rates in competition with genetically uniform populations than in competition with themselves.
Laboratory experiments with Daphnia pulex during their parthenogenetic phase set genetically varied and genetically uniform populations in competition for an impure food mix, simulating sexual-asexual coexistence. The model species for these tests were the freshwater crustacean Daphnia, with seasonally sexual and obligately parthenogenetic forms, and the littoral enchytraeid worm Lumbricillus lineatus, which has sexual diploid and pseudogamous triploid reproductive systems. P>The aim of this thesis was to investigate ecological conditions under which the genetic variation inherent to sexual reproduction may confer immediate competitive advantages over asexual reproduction. Characterizing partial DVM provides a more precise picture of aquatic ecosystems which can strongly influence estimates of population growth and trophic interactions. Thus, partial DVM in the population is neither a state-dependent behaviour based on size, nor the result of a genetic polymorphism. Furthermore, Hb-rich and Hb-poor individuals were present within all commonly found genotypes. We found that migration behaviour within Hb-rich and Hb-poor Daphnia was not related to individual size. This variation serves as a marker for differential use of a deep low-oxygen layer, which allows us to concurrently examine the relationships between individual state, genotype, and migration behaviour within the population. The Daphnia at our study site show intraspecific diversity in body hemoglobin (Hb) concentration. Here, we take an observational approach to identify the likely mechanisms maintaining partial DVM in a natural population of Daphnia pulicaria. However, the mechanisms maintaining partial DVM in zooplankton are poorly understood. This behaviour is widespread among aquatic invertebrates and can strongly influence interspecific competition. One example is partial diel vertical migration (DVM), wherein a portion of the population migrates vertically at night while another portion remains deep in the water column.
Daphnia and other zooplankton often harbour substantial intraspecific diversity in migration behaviour.