Dr. B.J.A. Pollux

Associate Professor Evolutionary Biology


Experimental Zoology Group

Department of Animal Sciences

Wageningen University

Zodiac, Building 122

Room E1233

De Elst 1

NL-6708 WD Wageningen

the Netherlands


Phone: +31.(0)317.486083 (my office)

Phone: +31.(0)317.483509 (secretary)

E-mail: bart.pollux@wur.nl

Web: http://www.bartpollux.nl




Twitter: @BartPollux

Wageningen University

Last updated: 15 March 2022

Three placental livebearing fish from the family Poeciliidae in the proces of giving birth: (left) Heterandria formosa, (middle) Poeciliopsis turneri and (right) Phalloptychus januarius. Photo credits: Mike Fleuren.

Welcome to the Pollux Placenta Lab


My research focuses on the evolution of complex reproductive adaptations, such as livebearing, superfetation and placentation. I am trying to understand: (i) what the ecological variables are that drive the evolution of these complex adaptations, (ii) what the anatomical, physiological and molecular changes are that underly their evolution, and (iii) what the consequences are of these novel adaptations for sexual selection and maternal-fetal interactions during development. To study these questions, we perform comparative studies at the species (macro-evolutionary) and population (micro-evolutionary) level to investigate the ecology, (stress) physiology, life history evolution, biomechanics, immunology, genomics and transcriptomics associated with these reproductive adaptations. We use Cyprinodontiform fishes because: (a) livebearing, superfetation and placentation independently evolved multiple times in this Order (i.e. in the family Poeciliidae, Anablepidae and Goodeidae), (b) these fish can be found in a range of different environments, (c) they have fast generation times, (d) are easy to keep and experiment with in the lab and (e) are very cool fish.

Selected Publications

  • van Kruistum H, Nijland R, Reznick DN, Groenen MAM, Megens H-J & Pollux BJA (2021) Parallel genomic changes drive the repeated evolution of placentas in live-bearing fish. Molecular Biology and Evolution 38:2627–2638.
  • Hagmayer A, Furness AI, Reznick DN, Dekker ML & Pollux BJA (2020) Predation risk shapes the degree of placentation in natural populations of live-bearing fish. Ecology Letters 23:831-840.
  • van Kruistum H, Guernsey MW, Baker JC, Kloet SL, Groenen MAM, Pollux BJA & Megens H-J (2020) The genomes of the livebearing fish species Poeciliopsis retropinna and Poeciliopsis turrubarensis reflect differences in the evolution of their reproductive strategy. Molecular Biology and Evolution 37:1376-1386.
  • Fleuren M, van Leeuwen JL & Pollux BJA (2019) Superfetation reduces the negative effects of pregnancy on the fast-start escape performance in live-bearing fish. Proceedings of the Royal Society of London B: Biological Sciences 286:20192245.
  • Furness AI, Pollux BJA, Meredith RW, Springer MS & Reznick DN (2019) How conflict shapes evolution in Poeciliid fishes. Nature Communications 10:3335.
  • Lankheet MJM, Stoffers T, van Leeuwen JL & Pollux BJA (2016). Innate and acquired prey capturing skills in superprecocial livebearing fish. Proceedings of the Royal Society of London B: Biological Sciences 283:20160972.
  • Pollux BJA, Meredith RW, Springer MS & Reznick DN (2014) The evolution of the placenta drives a shift in sexual selection in livebearing fish. Nature 513:233-236.
  • Pollux BJA, Pires MN, Banet AI & Reznick DN (2009) The evolution of placentas in the fish family Poeciliidae – An empirical study of macroevolution. Annual Review of Ecology, Evolution and Systematics 40:271-289.