Clonal diversity matters High levels of functional and genetic diversity occur in the model microzooplankter Oxyrrhis marina S chool of B iological S ciences S chool of B iological S ciences Chris Lowe, David Montagnes, Phill Watts

Microbial food webs are important in aquatic systems Many morphospecies are thought to be ubiquitous Phylogenetic data suggest this may be so (but results are ambiguous) But are we looking at the right aspects? Functional (phenotypic) diversity may be a more appropriate metric to assess distribution Introduction

A well characterised morphospecies A commonly used model organism An easy organism to grow Ubiquitous Introduction: Oxyrrhis marina Dujardin µm

Distribution

“Everything is everywhere, nature selects” Are we adequately examining diversity? Morphology Genetics Functional differences (phenotypes) Introduction: The BIG question A specific test case: O. marina One morphospecies Phylogenetic markers (different) Ecophysiological responses (different)

Phylogeography: Distribution

Phylogeography: Our data

Phylogeography: (5.8s ITS rDNA) 18s 5.8s 24s 5` 3` ITS 0.05 substitutions/site Plymouth CAP1133/3 IOM/PSM IOM/P IOM/S Bahrain CAP1133/4 Finland CCAP1133/5 Washington CCMP604 Caribbean CCMP1788 Connecticut CCMP1795 Florida CCMP605 Texas CCMP These are all Oxyrrhis (18s rDNA) 4 well-supported clades Large genetic differences Do they have a phylogeographic distribution? Lowe et al. 2005

Phylogeography: (5.8s ITS rDNA) They have no clear phylogeographic distribution

Ecophysiology: Is distribution related to function?

Habitat Environment

Oxyrrhis marina Pools vs coastal waters Salinity

Growth rate (  ) Salinity (ppt) Time numbers N t = N 0 e  t Ecophysiology: salinity

Salinity (ppt) Growth rate (  d -1 ) Location Geographical location 5.8s ITS sequence data Habitat: coastal, intertidal Habitat Coastal There appears to be a habitat specific response Ecophysiology and rDNA do not agree 2 growth rate responses Lowe et al. 2005

Morphology: inadequate resolution “Neutral” markers: rDNA does not explain observed distribution of clones Is everything everywhere?

We need to examine multiple clones to assess differences Ecophysiology: suggests distributional patterns based on habitat Our next step is to examine: Selection/adaptation Population structure/dispersal Neutral and Functional characteristics Interdisciplinary approach to biodiversity Conclusion

Breaking boundaries: quantifying the influence of demography and seascape in driving divergence in the protist Oxyrrhis marina Phill Watts, Chris Lowe, David Montagnes S chool of B iological S ciences S chool of B iological S ciences

This is a hypothesis describing processes of: Dispersal Adaptation Oxyrrhis marina: “Everything is everywhere, nature selects” It suggested distributions of micro-organisms are fundamentally different from macro-organisms To data there has been no explicit tests of this hypothesis for micro-organisms across landscapes

Distinct oceanographic boundaries (e.g. fronts, gyres, isthmuses, currents) Strong environmental gradients (temperature, salinity) The marine environment is heterogeneous

We will quantify relative roles of natural selection and random drift in driving divergence Spatial variation in adaptive traits i.e. salinity and temperature tolerance Demographic parameters e.g. population boundaries, population sizes migration rates Are these processes/parameters different between micro-organisms and macro-organisms? Oxyrrhis marina:

The heterogeneous marine environment provides a framework to examine adaptive/neutral variation Oxyrrhis marina and the marine environment

Collect O. marina samples from across Europe 2 scales:Northern Europe Irish and Celtic seas For each site: Isolate & culture replicate O. marina clones Genotype isolates Make phenotypic measurements Growth rate Cell size Gene expression (Na/K ATPase, HSP) Oxyrrhis marina and the marine environment

Gene expression Genetic and phenotypic diversity t1t1 r1r1 t2t2 r2r2 Microsatellite Genotyping Na/K ATPase expression Salinity Population growth rate Salinity N t = N 0 e  t Temperature morphology F st Q st

F st (dispersal) Measures of the extent of divergence between populations relative to the total diversity within all populations Based on neutral markers (e.g. microsatellites) Provides an indication of geneflow/dispersal between populations H T = heterozygosity in total population H S = average heterozygosity in subpopulations

σ 2 p(b) = phenotypic variance between populations σ 2 p(w) =average phenotypic variance within populations Q st (adaptive divergence) Measures of the extent of divergence between populations relative to the total diversity within all populations Based on phenotypic traits (e.g. ecophysiological responses, morphometrics) Provides an indication of adaptive divergence

Q st σ 2 p(b) = phenotypic variance between populations σ 2 p(w) =average phenotypic variance within populations

Salinity F st – Q st : comparison No dispersal barriers Fst↓ Identical environments Qst ↓ F st Q st ( pop n s connected, no adaptive divergence ) 01 (pop n s different, no adaptive divergence) Balancing selection Complete dispersal barrier Fst ↑ Identical environments Qst ↓ F st Q st 01

No dispersal barriers Fst↓ Different environments Qst ↑ Salinity F st Q st (pop n s connected, adaptive divergence) Spatially varying selection Salinity F st – Q st : comparison 01 Complete dispersal barrier Fst ↑ Different environments Qst ↑ (pop n s different, adaptive divergence) F st Q st 01

Gene expression Genetic and phenotypic diversity t1t1 r1r1 t2t2 r2r2 Microsatellite Genotyping Na/K ATPase expression Salinity Population growth rate Salinity N t = N 0 e  t Temperature morphology F st Q st

So, all we need to do is: 1.Collect many O. marina 2.Make measurements on neutral markers and phenotypic traits 3.Compare F st -Q st 4.Apply data to landscapes and boundaries 5.Test hypothesis that everything is everywhere and nature selects But it’s expensive to travel all over the place and would make a big carbon footprint Solution: we need your help to collect O. marina Oxyrrhis marina and the marine environment