- Vautierstraat 29
B-1000 Brussels - + 32 2 62 74 312
Isa Schön
Royal Belgian Institute of Natural Sciences, Freshwater Biology, Faculty Member
- Biology, Women's Studies, Evolutionary Biology, Genomics, Phylogeography, Phylogeny/phylogenetics, and 11 moreDNA repair, Freshwater Biology, Ecology, Bioinformatics, Paleontology, Systematics (Taxonomy), Phylogenetics, Phylogenetic Systematics, Animal Ecology, Freshwater Ecology, and Invasive species ecologyedit
- Isa Schön lives near Ghent in Belgium and researches the genetics of ostracods. She has a Ph.D. from the Philipps-Uni... moreIsa Schön lives near Ghent in Belgium and researches the genetics of ostracods. She has a Ph.D. from the Philipps-University Marburg and is a senior researcher at the Royal Belgian Institute of Natural Sciences, where she studies the phylogeny, molecular ecology, genomics and evolution of non-marine Ostracoda. She is also guest professor at Hasselt University where she teaches Molecular Ecology. She is participating in national and international research projects related to ostracods and conservation genetics of Belgian amphibians. She is also
* Editor-in-Chief of the Belgian Journal of Zoology
For submission, please see:
http://www.naturalsciences.be/institute/associations /rbzs_website/bjz
* Author of more than 140 scientific publications
* Recipient of a Marie-Curie research grant from the
European Union
* founder and boardmember of BeWiSe (Belgian
Women in Science)
http://www.bewise.be
Recent publications of the last 5 years:
1. Koenders A., Martens K., Halse S. & Schön I. 2012. Cryptic species of the Eucypris virens species complex (Ostracoda, Crustacea) have invaded Western Australia. Biol. Invasions, DOI 10.1007/s10530-012-0224-y.
2. Martens K., Halse S. & Schön I. 2012. Nine new species of Bennelongia DeDeckker & McKenzie, 1981 (Crustacea, Ostracoda) from Western Australia, with the description of one new subfamily. Europ. J. Taxonomy 8, 1-56.
3. Schön I, Eggermont H., Verheyen E. & Martens K. 2012. Palaeogenetics for ostracods. In: D. J. Horne, J. Holmes, F. Viehberg, J. Rodriguez-Lazaro (Eds), Ostracoda as proxies for Quaternary climate change, Elsevier, in press
4. Schön I., Pinto R., Halse S., Smith A., Martens K. & Birky C.W. JR 2012. Cryptic diversity in putative ancient asexual darwinulids (Crustacea: Ostracoda). PLoS ONE 7, e39844. doi:10.1371/journal.pone.0039844.
5. Van den Broecke L., Martens K. & Schön I. 2012. Ostracod valves as efficient UV protection. J. Limnol. 71, 119-124.
6. Schön I. & Martens K. 2012.Molecular analyses of ostracod flocks from Lake Baikal and Lake Tanganyika. Hydrobiologia, 682, 91-110.
7. Schön I., Raepsaet A. , Goddeeris B., Bauwens D., Mergeay J., Vanoverbeke J. & Martens K. 2011. High genetic diversity but limited gene flow in Flemish populations of the Crested newt, Triturus cristatus. Belg. J. Zool., 141, 3-13.
8. Bruvo R., Adolfsson S., Symonova R., Lamatsch D.K., Schön I., Jokela J., Butlin R.K. & Müller S. 2011. Few parasites, and no evidence for Wolbachia infections in a freshwater ostracod inhabiting temporary ponds. Biol. J. Linn. Soc., 102, 208-216.
9. Schön I. 2011. Doorbreek het glazen plafond! Het stappenplan voor vrouwen in de wetenschap. In: Deblonde, M. (ed.) Duizend bloemen en granaten. Over gender, wetenschap en technologie. Acco, Leuven, pp. 111-133.
10. Nunes Brandao S., Sauer J. & Schön I. 2010. Circumantarctic and eurybathid distribution in Southern Ocean benthos? A genetic test using Macrocyprididae (Crustacea, Ostracoda) as model organism. Mol. Phyl. Evol., 159, 219-243. doi:10.1016/j.ympev.2010.01.014 .
11. Schön I., Martens K. & Halse S. 2010. Genetic diversity in Australian ancient asexual Vestalenula (Ostracoda, Darwinulidae) – little variability down-under. Hydrobiologia, 641, 59-70. IF
12. Bode S.N.S., Lamatsch D.K., Martins M.J.F., Schmit O., Vandekerkhove J., Mezquita F., Namiotko T., Rossetti G., Schön* I., Butlin* R.K. & Martens* K. 2010. Exceptional cryptic diversity and multiple origins of parthenogenesis in a freshwater ostracod. Mol. Phyl. Evol. 54, 542–552. * these authors contributed equally
13. Schön I. 2010. A challenge for changes. Belg. J. Zool. 139, 1.
14. Vanbrabant J., Goddeeris B., Martens K. & Schön I. 2009. Development of primers for amplification and further research on the D-loop control region for the Common Spadefoot toad, Pelobates fuscus (Amphibia). Conserv. Genet. Resources 1, 495-499.
15. Martens K., Schön I., Meisch C. & Horne D.J. 2008. Global diversity of ostracods (Ostracoda, Crustacea) in freshwater. Hydrobiologia 595, 185-193.
16. Martens K. & Schön I. 2008. Opinion: Ancient asexuals; darwinulids not exposed. Nature 453: 587.
17. Schön I. 2007. Did Pleistocene glaciations shape genetic patterns of European ostracods? A phylogeograpic analysis of two species with asexual reproduction. Hydrobiologia 575, 30-50. IF 1.964
18. Schön I., Martens,K. & Van Dijk P. (eds.) 2009. Lost sex. The evolutionary biology of parthenogenesis. 615 pp., 27 chapters and 96 figures. Springer Academic Publishers, Dordrecht.
19. Schön I., Rossetti G. & Martens K. 2009. Ancient asexual darwinulids: ancient scandals or scandalous gossip? In: Schön I., Martens K. & Van Dijk P. (eds.) Lost sex. The evolutionary biology of parthenogenesis. Springer Academic Publishers, Dordrecht, pp. 217-240.
20. Loxdale H., Schön I. & Martens K. 2009. The elusive clone. In: Schön I., Martens K. & Van Dijk P. (eds.) Lost sex. The evolutionary biology of paredit
Research Interests: Evolutionary Biology, Genetics, Zoology, Geography, Molecular Evolution, and 17 moreCrustacea, Phylogeny, Mitochondrial DNA, Parthenogenesis, Europe, Haplotypes, Female, Animals, Male, Cluster Analysis, Molecular phylogeny, Cryptic Species, Molecular Phylogenetics and Evolution, Asexual Reproduction, Mediterranean region, Bayes Theorem, and Evolution of Sex
Research Interests:
Parthenogenetic lineages within non-marine ostracods can occur either in mixed (with sexual and asexual females) or exclusively asexual taxa. The former mode of reproduction is associated with a high intraspecific diversity at all levels... more
Parthenogenetic lineages within non-marine ostracods can occur either in mixed (with sexual and asexual females) or exclusively asexual taxa. The former mode of reproduction is associated with a high intraspecific diversity at all levels (genetic, morphological, ecological) and, at least in the Cypridoidea, with geographical parthenogenesis. Obligate asexuality is restricted to the Darwinuloidea, the strongest candidate for an ancient asexual animal group after the bdelloid rotifers, and is characterized by low diversity. We have compared rates of molecular evolution for the nuclear ITS1 region and the mitochondrial COI gene amongst the three major lineages of non-marine ostracods with sexual, mixed and asexual reproduction. Absolute rates of molecular evolution are low for both regions in the darwinulids. The slow-down of evolution in ITS1 that has been observed for Darwinula stevensoni (Brady & Robertson) apparently does not occur in other darwinulid species. ITS1 evolves more slowly than COI within non-marine ostracod families, including the darwinulids, but not between superfamilies. The ancient asexuals might have a higher relative substitution rate in ITS1, as would be expected from hypotheses that predict the accumulation of mutations in asexuals. However, the speed-up of ITS could also be ancient, for example through the stochastic loss of most lineages within the superfamily after the Permian–Triassic mass extinction. In this case, the difference in rate would have occurred independently from any effects of asexual reproduction. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 79, 93–100.
Research Interests:
We redescribe Strandesia tolimensis Roessler, 1990, originally described from Colombia, and describe three new species, Strandesia lansactohai n. sp., S. velhoi n. sp. and S. nupelia n. sp. from lakes, channels and rivers in the alluvial... more
We redescribe Strandesia tolimensis Roessler, 1990, originally described from Colombia, and describe three new species, Strandesia lansactohai n. sp., S. velhoi n. sp. and S. nupelia n. sp. from lakes, channels and rivers in the alluvial valley of the upper Paraná River. Mainly valve morphology and shape and size of the attachment of the caudal ramus are used to characterize these species, as other soft parts are uninformative. All populations studied here are parthenogenetic, so male morphologies are not available. Sequences of the mitochondrial COI-gene are used to construct a phylogeny, as well as a genetic network of specimens, and in both analyses the four species are well-supported. In addition, we also delimit the four species with genetic distances using Birky’s K/θ method and conclude that it supports the identity of the species under consideration.
Fully asexually reproducing taxa lack outcrossing. Hence, the classic Biological Species Concept cannot be applied. Methodology/Principal Findings We used DNA sequences from the mitochondrial COI gene and the nuclear ITS2 region to check... more
Fully asexually reproducing taxa lack outcrossing. Hence, the classic Biological Species Concept cannot be applied.
Methodology/Principal Findings
We used DNA sequences from the mitochondrial COI gene and the nuclear ITS2 region to check species boundaries according to the evolutionary genetic (EG) species concept in five morphospecies in the putative ancient asexual ostracod genera, Penthesilenula and Darwinula, from different continents. We applied two methods for detecting cryptic species, namely the K/θ method and the General Mixed Yule Coalescent model (GMYC). We could confirm the existence of species in all five darwinulid morphospecies and additional cryptic diversity in three morphospecies, namely in Penthesilenula brasiliensis, Darwinula stevensoni and in P. aotearoa. The number of cryptic species within one morphospecies varied between seven (P. brasiliensis), five to six (D. stevensoni) and two (P. aotearoa), respectively, depending on the method used. Cryptic species mainly followed continental distributions. We also found evidence for coexistence at the local scale for Brazilian cryptic species of P. brasiliensis and P. aotearoa. Our ITS2 data confirmed that species exist in darwinulids but detected far less EG species, namely two to three cryptic species in P. brasiliensis and no cryptic species at all in the other darwinulid morphospecies.
Conclusions/Significance
Our results clearly demonstrate that both species and cryptic diversity can be recognized in putative ancient asexual ostracods using the EG species concept, and that COI data are more suitable than ITS2 for this purpose. The discovery of up to eight cryptic species within a single morphospecies will significantly increase estimates of biodiversity in this asexual ostracod group. Which factors, other than long-term geographic isolation, are important for speciation processes in these ancient asexuals remains to be investigated.
Methodology/Principal Findings
We used DNA sequences from the mitochondrial COI gene and the nuclear ITS2 region to check species boundaries according to the evolutionary genetic (EG) species concept in five morphospecies in the putative ancient asexual ostracod genera, Penthesilenula and Darwinula, from different continents. We applied two methods for detecting cryptic species, namely the K/θ method and the General Mixed Yule Coalescent model (GMYC). We could confirm the existence of species in all five darwinulid morphospecies and additional cryptic diversity in three morphospecies, namely in Penthesilenula brasiliensis, Darwinula stevensoni and in P. aotearoa. The number of cryptic species within one morphospecies varied between seven (P. brasiliensis), five to six (D. stevensoni) and two (P. aotearoa), respectively, depending on the method used. Cryptic species mainly followed continental distributions. We also found evidence for coexistence at the local scale for Brazilian cryptic species of P. brasiliensis and P. aotearoa. Our ITS2 data confirmed that species exist in darwinulids but detected far less EG species, namely two to three cryptic species in P. brasiliensis and no cryptic species at all in the other darwinulid morphospecies.
Conclusions/Significance
Our results clearly demonstrate that both species and cryptic diversity can be recognized in putative ancient asexual ostracods using the EG species concept, and that COI data are more suitable than ITS2 for this purpose. The discovery of up to eight cryptic species within a single morphospecies will significantly increase estimates of biodiversity in this asexual ostracod group. Which factors, other than long-term geographic isolation, are important for speciation processes in these ancient asexuals remains to be investigated.
Ancient lakes are excellent laboratories for evolutionary research, where species can be studied in the cradle where they originated. In this article, we investigate two endemic ostracod species flocks from the two oldest lakes in the... more
Ancient lakes are excellent laboratories for evolutionary research, where species can be studied in the cradle where they originated. In this article, we investigate two endemic ostracod species flocks from the two oldest lakes in the world, Lake Baikal (LB) (ca. 28 myr) and Lake Tanganyika (LT) (ca. 12 myr), with DNA sequence data. Nuclear ITS1 failed to resolve the phylogeny of both flocks. Whilst most phylogenetic relationships of the Tanganyika flock are resolved with mitochondrial COI, the Baikalian tree contains multifurications of up to seven different clades. The Tanganyikan Cyprideis flock shows higher genetic variability, which matches its higher morphological variability. A significant deviation from a constant divergence rate through time indicates that the Cytherissa flock most likely experienced explosive speciation events during its earlier history. Comparative analyses of substitution rates furthermore revealed that they are not clock-wise for COI. Ancestral Cytherissa probably radiated in LB 5–8 myr ago, around the time when the cold, oxygenated abyss was formed in LB. The Tanganyikan Cyprideis flock is almost twice as old as the Baikalian Cytherissa flock, and possibly older than LT itself, ca. 15 myr. The Cyprideis flock has survived drastic lake level changes and resulting salinity crises during its entire history.
Eucypris virens, an ostracod with mixed reproduction and Holarctic distribution, forms a species complex with more than 35 cryptic species in Europe. Here, we analysed COI and LSU DNA sequence data from Western Australian E. virens to... more
Eucypris virens, an ostracod with mixed reproduction and Holarctic distribution, forms a species complex with more than 35 cryptic species in Europe. Here, we analysed COI and LSU DNA sequence data from Western Australian E. virens to distinguish between the possibilities that vicariant processes have led to the formation of Australian E. virens species or that these ostracods have been introduced into Western Australia. Phylogenetic reconstructions, genetic networks and estimates of genetic distances all show clearly that Western Australian and European E. virens are very closely related. Some haplotypes are identical, others are only separated by one or two mutational steps. Among the Western Australian representatives of E. virens, three phylogenetic clades can be distinguished. We identified three European cryptic species as ancestors for two of the Western Australian clades and one close relative to the third Western Australian clade. We therefore conclude that E. virens has been introduced into Western Australia, most likely from western Europe, and did not diverge in Australia. In Europe, E. virens shows a typical pattern of geographic parthenogenesis while we found only asexual populations in Western Australia.
The genus Bennelongia De Deckker & McKenzie, 1981 is most likely endemic to Australia and New Zealand and, up to now, only two described species in this genus had been reported from Western Australia. Extensive sampling in Western... more
The genus Bennelongia De Deckker & McKenzie, 1981 is most likely endemic to Australia and New Zealand and, up to now, only two described species in this genus had been reported from Western Australia. Extensive sampling in Western Australia revealed a much higher specific diversity. Here, we describe nine new species in three lineages, within the genus Bennelongia: B. cygnus sp. nov. and B. frumenta sp. nov. in the B. cygnus lineage, B. gwelupensis sp. nov., B. coondinerensis sp. nov., B. cuensis sp. nov., B. lata sp. nov. and B. bidgelangensis sp. nov. in the B. australis lineage, and B. strellyensis sp. nov. and B. kimberleyensis sp. nov. (from the Pilbara and Kimberley regions respectively) in the B. pinpi-lineage. For six of the nine species, we were also able to construct molecular phylogenies and to test for cryptic diversity with two different methods based on the evolutionary genetic species concept, namely Birky’s 4 x rule and the GYMC model. These analyses support the specific nature of at least four of the five new species in the B. australis lineage and of the two new species in the B. pinpi lineage. We also describe Bennelongiinae n.subfam. to accommodate the genus. With the nine new species described here, the genus Bennelongia now comprises 15 species, but several more await formal description.
One of the major consequences of climate change is the increase of ultraviolet radiation, especially UVB (280-315 nm). This has important consequences for organisms and ecosystems. In surface freshwater ecosystems with transparent water,... more
One of the major consequences of climate change is the increase of ultraviolet radiation, especially UVB (280-315 nm). This has important consequences for organisms and ecosystems. In surface freshwater ecosystems with transparent water, UV can easily penetrate deeply. Here, we used three different experimental approaches to examine the response of non-marine ostracods and cladocerans to UVB radiation: estimating lethal doses, determining how much UVB is blocked by the valves, and analysing valve chemical compositions. For most investigated crustaceans, we found a strong correlation between the amount of UVB that is blocked by the valves and the lethal UVB doses. Most ostracod valves blocked between 60% and 80% of UVB radiation, thus providing effective shielding. Pigmented species from temporary habitats were best protected. These species also showed high lethal UVB doses of 110 kJ m 2 to 214 kJ m 2. In the waterflea Daphnia magna, valves only stopped ca 35% of UVB radiation, and the lethal dose was half that of the doses estimated for ostracods. Since there were no significant differences in chemical composition of the valves between the investigated species, other factors must be responsible for the observed differences, which remain to be identified.
Habitat destruction and fragmentation are among the major causes of amphibian decline. We investigated to what extent geographic distance and barriers affect the genetic composition of the crested newt, Triturus cristatus in Flanders... more
Habitat destruction and fragmentation are among the major causes of amphibian decline. We investigated to what
extent geographic distance and barriers affect the genetic composition of the crested newt, Triturus cristatus in Flanders (North
Belgium), causing inbreeding or loss of genetic diversity. Data from seven microsatellite loci and 170 individuals from seven meta-
populations up to 180km apart revealed heterozygosities of 0.53 to 0.67 within populations and moderate levels of genetic diver-
gence between populations (FST values from 0.074 to 0.141, harmonic means of Dest
between 0.070 and 0.189). In all Flemish
meta-populations, more than 90% of the individuals from a given geographic region were assigned to the same genetic cluster indi-
cating little genetic exchange, even in De Panne where the two populations Oosthoek and Westhoek are only a few kilometres
apart. Such sub-structuring on a micro-scale has also been described in other amphibians. Unique alleles in most populations fur-
ther support the probability that genetic drift has already led to some isolation. With the exception of the Oosthoek population,
however, we found no significant evidence for bottlenecks. Connectivity within pool clusters seems essential to the maintenance of
genetic diversity in crested newts as is indicated by our findings from Tommelen, the population with the largest number of pools in
close proximity, which also shows the highest levels of heterozygosity (He
and Ho) and the second highest number and richness of
alleles.
In conclusion, our study indicates that dispersal and migration rates between the Flemish populations of Triturus cristatus are limited
at the geographic scale studied here but that habitat fragmentation has not yet led to a significant loss of genetic diversity of the studied
Flemish populations, possibly because crested newts are relatively long-lived, fragmentation of their habitat is relatively recent in
Flanders, and most investigated pools are still connected at the local scale.
extent geographic distance and barriers affect the genetic composition of the crested newt, Triturus cristatus in Flanders (North
Belgium), causing inbreeding or loss of genetic diversity. Data from seven microsatellite loci and 170 individuals from seven meta-
populations up to 180km apart revealed heterozygosities of 0.53 to 0.67 within populations and moderate levels of genetic diver-
gence between populations (FST values from 0.074 to 0.141, harmonic means of Dest
between 0.070 and 0.189). In all Flemish
meta-populations, more than 90% of the individuals from a given geographic region were assigned to the same genetic cluster indi-
cating little genetic exchange, even in De Panne where the two populations Oosthoek and Westhoek are only a few kilometres
apart. Such sub-structuring on a micro-scale has also been described in other amphibians. Unique alleles in most populations fur-
ther support the probability that genetic drift has already led to some isolation. With the exception of the Oosthoek population,
however, we found no significant evidence for bottlenecks. Connectivity within pool clusters seems essential to the maintenance of
genetic diversity in crested newts as is indicated by our findings from Tommelen, the population with the largest number of pools in
close proximity, which also shows the highest levels of heterozygosity (He
and Ho) and the second highest number and richness of
alleles.
In conclusion, our study indicates that dispersal and migration rates between the Flemish populations of Triturus cristatus are limited
at the geographic scale studied here but that habitat fragmentation has not yet led to a significant loss of genetic diversity of the studied
Flemish populations, possibly because crested newts are relatively long-lived, fragmentation of their habitat is relatively recent in
Flanders, and most investigated pools are still connected at the local scale.
Research Interests:
Research Interests: Evolutionary Biology, Genetics, Zoology, Geography, Algorithms, and 14 morePopulation Genetics, Crustacea, Phylogeny, Southern Ocean, Mitochondrial DNA, Sequence alignment, Genetic Testing, Haplotypes, Animals, Molecular Phylogenetics and Evolution, Zoogeography, Geographic distribution, Geographic Range, and Likelihood Functions
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Sex is the queen of problems in evolutionary biology. Generations of researchers have investigated one of the last remaining evolutionary paradoxes: why sex exists at all. Given that sexual reproduction is costly from an evolutionary... more
Sex is the queen of problems in evolutionary biology. Generations of researchers have investigated one of the last remaining evolutionary paradoxes: why sex exists at all. Given that sexual reproduction is costly from an evolutionary point of view, one could wonder why not all animals and ...
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Page 1. Journal of Natural History, 2002, 36, 379390 OPINION articles represent the per-sonal views of invited experts. They are intended to stimulate debate in the CORRESPONDENCE section (see Instructions to Authors). OPINION Are... more
Page 1. Journal of Natural History, 2002, 36, 379390 OPINION articles represent the per-sonal views of invited experts. They are intended to stimulate debate in the CORRESPONDENCE section (see Instructions to Authors). OPINION Are ancient asexuals less burdened? ...
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What are Ostracoda? A cladistic analysis of the extant super-families of the subclasses Myodocopa and Podocopa (Crustacea: Ostracoda) DAVID J. HORNE1, ISA SCHÖN2, ROBIN J. SMITH3 & KOEN MARTENS2, 4 1 Department of Geography, Queen... more
What are Ostracoda? A cladistic analysis of the extant super-families of the subclasses Myodocopa and Podocopa (Crustacea: Ostracoda) DAVID J. HORNE1, ISA SCHÖN2, ROBIN J. SMITH3 & KOEN MARTENS2, 4 1 Department of Geography, Queen Mary, University of London, ...
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KARINE VAN DONINCK*, , ISA SCHO¨ N*, FRE MAES, LUC DE BRUYN, § AND KOEN MARTENS*, *Freshwater Biology Section, Royal Belgian Institute of Natural Sciences, Brussels, Belgium Free University of Brussels (VUB), Brussels, Belgium... more
KARINE VAN DONINCK*, , ISA SCHO¨ N*, FRE MAES, LUC DE BRUYN, § AND KOEN MARTENS*, *Freshwater Biology Section, Royal Belgian Institute of Natural Sciences, Brussels, Belgium Free University of Brussels (VUB), Brussels, Belgium Evolutionary ...