title: Isolation by Time During an Arctic Phytoplankton Spring Bloom.
abstract: The arctic phytoplankton spring bloom, which is often diatom-dominated, is a key event that provides the high latitude communities with a fundamental flux of organic carbon. During a bloom, phytoplankton may increase its biomass by orders of magnitude within days. Yet, very little is known about phytoplankton bloom dynamics, including for example how blooming affects genetic composition and diversity of a population. Here, we quantified the genetic composition and temporal changes of the diatom Fragilariopsis cylindrus, which is one of the most important primary producers in the Arctic, during the spring bloom in western Greenland, using 13 novel microsatellite markers developed for this study. We found that genetic differentiation (quantified using sample-specific FST) decreased between time points as the bloom progressed, with the most drastic changes in FSToccurring at the start of the bloom; thus the genetic structure of the bloom is characterized by isolation by time. There was little temporal variation in genetic diversity throughout the bloom (mean HE= 0.57), despite marked fluctuations in F. cylindrus cell concentrations and the temporal change in sample-specific FST. On the basis of this novel pattern of genetic differentiation, we suggest that blooming behavior may promote genetic diversity of a phytoplankton population.
authors.affiliation: Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, Copenhagen K, 1307, Denmark.
authors.forename: Anna
authors.initials: A
authors.lastname: Tammilehto
authors.affiliation: Department of Ecology, University of Oulu, Oulu, FI-90014, Finland.
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Watts
authors.affiliation: Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, Copenhagen K, 1307, Denmark.
authors.forename: Nina
authors.initials: N
authors.lastname: Lundholm
mesh_terms: D000704:Analysis of Variance; D001110:Arctic Regions; D044822:Biodiversity; D018533:Biomass; D017377:Diatoms / Q000254:growth & development / Q000302:isolation & purification; D005838:Genotype; D060005:Genotyping Techniques; D006116:Greenland; D018895:Microsatellite Repeats / Q000235:genetics; D010839:Phytoplankton / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification*; D011157:Population Dynamics; D012621:Seasons; D013696:Temperature; D013997:Time Factors
keywords: 
  Fragilariopsis cylindrus
  ; Diatom; microsatellites; population dynamics; population genetics