Manon de Visser

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I am fascinated by the evolutionary mechanisms that shape the natural world. Most specifically by what happens when species become threatened, or populations become isolated. When species adapt to their changing environments, it sometimes happens that nature - oddly enough - "fools" itself as a result of basic, evolutionary principles. Thus, as a PhD candidate I currently work on explaining how a weird, evolutionary flaw in crested and marbled newts of the genus Triturus evolved. My project is a collaboration between Naturalis and the Institute of Biology Leiden (IBL). Next to this project, I am also involved with nature conservation, (genetically) monitoring exotic amphibians and telling the stories of our researches through 'scicomm'.


Balanced Lethal System, Evolution, Conservation, Genetics, Genomics, Inbreeding, Evo-Devo, Embryology, Newts, Salamanders, Amphibians, Gene Expression, Invasive species, Exotics, Science Communication, Scicomm

Manon de Visser

PhD Candidate / Guest Researcher
PhD Council member
Understanding Evolution
+31 (0)6 48 396 715

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Lethal Systems

Photo of a crested newtI am a member of the Wielstra lab (ERC Starting Grant-funded research), where we study the genomics underlying the best-known case of a balanced lethal system: chromosome 1 syndrome in Triturus newts. Balanced lethal systems are considered an evolutionary failure, because natural selection is unable to get rid of the associated recessive, lethal alleles. I investigate the lethality and evolutionary origin of this system in collaboration with IBL. Are you curious to find out more? Just click here to read about balanced lethal systems!


What is it like to work as a PhD in the field of genomics, for both Naturalis and the University of Leiden? And what do I actually learn from the salamanders - and other animals - that I study? I find it important to share my knowledge and experiences with the world!

Manon with an enlarged, 3D-printed skull of a crested newt (genus: Triturus)


Scientific Publications:

  • Van der Groot, A., De Visser, M., Hiemstra, A.F. (2022) Smooth newts Lissotriton vulgaris observed hibernating in a waterfowl nest. Herpetological Bulletin: 162: 41-42.
  • Kuijt, M., Oskam, L., Den Boer, I., Dufresnes, C., France, J., Gilbert, M. J., De Visser, M.C., Struijk, R.P.J.H, Wielstra, B. (2022) The introduction of three cryptic tree frog species in the Dutch coastal dunes challenges conservation paradigms. Amphibia-Reptilia (published online ahead of print 2022)
  • Koster, S., Prins, N., Dufresnes, C., France, J., De Visser, M.C., Sruijk, R.P.J.H., Wielstra, B. The conservation paradox of an introduced population of a threatened species: spadefoot toads in the coastal dunes of the Netherlands. Amphibia-Reptilia (published online ahead of print 2022)
  • De Brouwer, J., Helder, B., France, J., De Visser, M.C., Struijk, R.P.J.H., Wielstra, B. An isolated crested newt population in Dutch coastal dunes: distribution relict or introduction? Amphibia-Reptilia (published online ahead of print 2022)
  • Vliegenthart, C., Van de Vrede, M., Den Boer, I., Gilbert, M., Lemmers, P., France, J., De Visser, M.C., Struijk, R.P.J.H., Wielstra, B. The limits of mtDNA barcoding for determining the provenance of invasive species: a midwife toad example. Amphibia-Reptilia (published online ahead of print 2022)
  • De Visser M., Prins E., Bosse M., Crooijmans R., Ter Meulen T. (2022). Maximum longevity and juvenile mortality in zoo-housed mangabeys. Zoo biology: 1-11.
  • Fahrbach M., De Visser M.C., Wielstra B.M. The hybrid zone between the Italian and Northern crested newts (Triturus carnifex and T. cristatus) reaches Germany, Salamandra 57(3): 428-434.
  • De Visser M.C., Liu, L., Bosse, M. (2021). Pygmy hogs, Current Biology 31(8):R366-R368.
  • Liu, L., Bosse, M., Megens, H.J., De Visser, M.C., Groenen, M.A.M., Madsen, O. (2020) "Genetic consequences of long‐term small effective population size in the critically endangered pygmy hog." Evolutionary Applications 14:710-720.
  • Van Tuijl, C., Van Bochove, K., De Visser, M.C. (2019). Genetic Structure of Badger Populations in a Fragmented Landscape: How Do Barriers Affect Populations on a Genetic Level? Lutra 62: 65-76.

Popular Science Articles:

  • Struijk, R.P.J.H., Backx, B., Demirkapu, B., De Visser, M., Wielstra, B. (2022). 'Rise and fall' van een populatie westelijke smaragdhagedissen in Scheveningen. RAVON 24(4): 24-27.
  • Helder B., De Brouwer J., Ouwehand J., De Visser M. & Wielstra B. (2021). Koi-kamsalamander, Schubben & Slijm (48): 8.
  • Meilink W.R.M., France J., De Visser M. C. & Wielstra B. (2021). Balanced Lethal Systems: An Evolutionary Mystery. Frontiers For Young Minds. 9:632945.
  • De Visser M.C., France J.M., Meilink W.R.M. & Wielstra B.M. (2021). Een evolutionair raadsel: het dodelijke chromosoom 1 syndroom in Triturus-salamanders, RAVON 23(1): 9-12.
  • Struijk R.P.J.H, Demirkapu B., De Visser M.C. & Wielstra B.M. (2021). Exotische smaragdhagedissen in de duinen bij Scheveningen, Kijk op Exoten (34): 12-13.

Awards & Prizes:

  • "1st prize for one-minute pitch" at the Netherlands Society of Evolutionary Biology PhD & Postdoc meeting 2021 (NLSEB2021), for the pitch: "The balanced lethal system in Triturus: an evolutionary trap!"
  • "3rd best oral presentation" at the Programming For Evolutionary Biology Conference 2021 (miniPEB2021), Freie Universität Berlin, for the talk: "Studying the lethality and evolutionary origin of the balanced lethal system in Triturus newts".
  • "1st prize for oral presentation" within subtheme: Global Health - Humans and Animals" at the University of Copenhagen EuroLeague of Life Sciences (ELLS) Student Conference 2017, for the MSc project "The Importance of Genomics for the Conservation Management of the Critically Endangered Pygmy Hog (Porcula salvania)".
  • "Best oral presentation" at the Benelux International Society of Applied Ethology (ISAE) meeting 2016, for the MSc project "The effect of exposure to visitors on stress in the critically endangered blue-eyed black lemur (Eulemur flavifrons) and other primate species at Apenheul Primate Park, the Netherlands."