Winkler, Lennart

Tribolium Lab – Janicke & Winkler

WinklerI am PhD student, supervised by Tim Janicke and Klaus Reinhardt.
My project examines how sexual selection is aligned with natural selection. We aim to investigate the influence of sexual selection on the capacities for adaption of species to novel environments and its influence on population fitness. Theory predicts that by reducing the frequency of deleterious mutations / mutation load, sexual selection might increase overall population fitness, while for example sexual conflict might reduce it. In this project we will (amongst other techniques) apply meta-analyses and experimental evolution (using the model system Tribolium castaneum) to test these hypotheses.

Some current interests are: Sexual selection, sperm competition, selfish genetic elements, genic capture, plasticity


  • Winkler L, Moiron M, Morrow EH, Janicke T. Stronger net selection on males across animals. eLife. Nov 17, 2021
  • Winkler L, Lindholm AK, Ramm SA, Sutter A. The baculum affects paternity success of first but not second males in house mouse sperm competition. BMC Ecol Evol. 2021;21(159).
  • Carlitz, E. H. D. et al. Steroid hormones in hair reveal sexual maturity and competition in wild house mice (Mus musculus domesticus). Sci. Rep. 9, 1–10 (2019).
  • Winkler, L., Kirch, L. M., Reinhold, K. & Ramm, S. A. Impact of low sperm competition on male reproductive trait allometries in a bush-cricket. BMC Evol. Biol. 19, 185 (2019).
  • Winkler, L. & Ramm, S. A. Experimental evidence for reduced male allocation under selfing in a simultaneously hermaphroditic animal. Biol. Lett. 14, (2018).

Building BIO Room 257
Twitter: @lennarthamburg

Current students:
Ronja Eilhardt (BSc Student) – Thesis on ‘Impact of population density on sexual selection in the red flour beetle’

Emma Markwardt (BSc Student) – Thesis on ‘Sex-specific genetic variance under heat stress in the red flour beetle’
Birte Martens (BSc Student) – Thesis: ‘No Evidence for Benefits of Same-Sex Copulations in Red Flour Beetles

BSc and MSc projects in the Tribolium lab

We are happy to host projects and/or theses in one of the outlined or self-developed projects. If you are interested in joining our team, please get in contact.Tribolium_Research_lable_Mina_2020

Evolutionary and behavioural biology

Supervisor: Dr. Tim Janicke, Lennart Winkler (BIO Room 257)
Study organism: red flour beetle Tribolium castaneum
Project start: From summer 2021

1. Strategic sperm allocation in the red flour beetle

Not only females but also males are expected to allocate their gametes prudently. Sexual selection theory predicts that males should adjust the number of transferred sperm in response to the risk of sperm competition. In T. castaneum males transfer a spermatophore to the female, containing sperm and seminal fluid (Qazi et al. 2015). It has been shown that the spermatophore is apparently only filled with sperm by the male, after the spermatophore is already transferred to the female (Fedina 2007). This might enable males to plastically adjust the amount of transferred sperm during mating. We might test the hypothesis of plastic sperm allocation in response to sperm competition by comparing the number of transferred sperm between virgin and mated females or between females of different size. This project requires preliminary experiments to establish a protocol to quantify the amount of sperm transferred to a female. The project would involve observation of mating behaviour and sperm microscopy techniques.

2. Morphology of male reproductive organs

The morphology of the male penis has potentially substantial influence on the reproductive success of males. This implies that sexual selection influences the evolution of male genital morphology. The male genital morphology of Tribolium castaneum might play an important role in male fertilization success, by influencing the outcome sperm competition and post-copulatory female choice (Haubruge et al. 1999; Arnaud et al. 2001). We would like to quantify male genital morphology (length measures and geometric morphometrics) to investigate if these measures influence male paternity success. Furthermore, one could study the allometry of the male penis to infer selective pressures. This project requires preliminary experiments to establish a protocol to dissect and measure the male copulatory organ. The project would include microscopy techniques and potentially behavioural observations.


Arnaud L, Haubruge E, Gage MJG. 2001. Morphology of Tribolium castaneum male genitalia and its possible role in sperm competition and cryptic female choice. Belg J Zool.(131 (2)):111–115.

Conner J. 1989. Density-dependent sexual selection in the fungus beetle, Bolitotherus cornutus. Evolution (N Y). 43(7):1378–1386.

Fedina TY. 2007. Cryptic female choice during spermatophore transfer in Tribolium castaneum (Coleoptera: Tenebrionidae). J Insect Physiol. 53(1):93–98.

Fedina TY, Lewis SM. 2008. An integrative view of sexual selection in Tribolium flour beetles. Biol Rev. 83:151–171.

Lewis SM, Tigreros N, Fedina T, Ming QL. 2012. Genetic and nutritional effects on male traits and reproductive performance in Tribolium flour beetles. J Evol Biol. 25(3):438–451.

Qazi MCB, Herbeck JT, Lewis SM. 2015. Mechanisms of Sperm Transfer and Storage in the Red Flour Beetle ( Coleoptera : Tenebrionidae ). Ann Entomol Soc Am. 89(6):892–897.