Welcome to my personal webpages at the University of Amsterdam.
I am assistant professor in Evolutionary Population Biology at the Institute for Biodiversity and Ecosystem Dynamics.
Currently, I am supervising three PhD students:
Graduated PhD students:
Please do refer to the information on my research, teaching activities and publications, which can be accessed through the navigation bar at the top of this page.
Generally, I am interested in social evolution and multi-level selection, and have worked on projects related to: effects of learning on the evolution of exploitation strategies of mite predators (with Beata Sznajder; PhD awarded September 2010), evolution of prudent predation in the predatory mite Phytoseiulus persimilis (with Alexandra Revynthi; PhD awarded December 2017), evolution of diapause (with Annemarie Kroon, postdoc), communicating the nature of danger in thrips (with Paulien de Bruijn - see also below; PhD awarded June 2015), and evolution of the interaction between cytoplasmic bacteria and the animal hosts they infect (with Filipa Vala and Hans Breeuwer). More recently, I have also worked on alternative male mating tactics in the two-spotted spider mite, Tetranychus urticae, with Yukie Sato. My research focus is in the combined experimental and theoretical study of evolutionary dynamics (i.e., feedbacks between evolutionary and ecological processes - nowadays called eco-evolutionary dynamics - and the role of genetic factors in determining these dynamics). In this context I have worked with various collaborators on 1) the evolution of specialization in herbivorous arthropods, and 2) the evolution of cooperation and altruism in humans and arthropods.
Specialization is a widespread biological phenomenon, particularly among herbivorous arthropods, and its evolutionary explanation therefore poses important questions. With Sara Magalhaes and Isabelle Olivieri (University of Montpellier), I studied patterns of local adaptation to new host plants using an experimental evolution approach with T. urticae. Our main findings were that local adaptation builds up trade-offs between performance on two new host plants and that phenotypic plasticity (in the form of maternal effects) plays a large role in the evolutionary response to new host plants. With Nicola Tien (PhD awarded November 2010), I studied the evolutionary genetics of life-history traits of T. urticae, such as development time, juvenile survival or egg-laying rate. Of all life-history traits, egg-laying rate stood out as a trait with high additive genetic variance (resulting in a high degree of heritability) as well as strong effects of (partly recessive) deleterious variation. The latter finding suggests that host-plant specialization in this species may be explained by “mutation accumulation” rather than fitness trade-offs, a theoretical possibility that has not been tested in herbivorous arthropods. With Bram Knegt (PhD student, UvA) I currently study aspects of host plant specialization of the spider mite Tetranychus evansi, which is on record as a specialist on solanaceous plants. We are assessing genetic variation in the ability of this mite to suppress direct defence mechanisms in its host plant tomato.
Explaining the evolution and maintenance of cooperation among unrelated individuals is one of the fundamental problems in biology and the social sciences. To study this problem, I have set up collaboration with Aljaz Ule, Eva van den Broek, Matthijs van Veelen and Arthur Schram (Experimental Economics, UvA) and Arno Riedl (Behavioural Economics, Maastricht University) to study the interactive evolution of social norms and cooperation. Experiments confirmed a role for group competition in within-group cooperation. Also, we showed that humans use both personal experience and reputation information about others in helping decisions, and that humans show distinct moral rules in assessing reputation information (with Eva van den Broek, PhD awarded January 2014, and Lucas Molleman, PhD awarded at Groningen University, February 2014). Theoretical study focused on the role of mutation in the maintenance of cooperation by direct reciprocity, and on sexual selection for cooperative behaviour (with Mathias Spichtig, PhD awarded June 2013). I also study spiteful behaviour (male killing) in social spider mites (with Yukie Sato), and alarm communication in thrips (with Paulien de Bruijn, PhD awarded June 2015). We have shown that thrips larvae exhibit context-dependent communication of predation danger (relating to predator nearby vs actual predator attack) by means of varying the ratio of two chemical components in their alarm pheromone, and showing appropriate responses to the various alarm signals. We also showed that thrips larvae can recognize kin. Taken together this means that we now have a lab system for studying the evolutionary mechanisms that in theory can maintain such a communication system, a topic of general interest that is so far only investigated in prairie dogs, ground squirrels and several other mammals under natural conditions.
My expertise in both theory and experiments on specialization has led to collaboration with the group of Jef Huisman (Aquatic Microbiology, University of Amsterdam) on the evolution of specialization and life-history traits in phytoplankton and their herbivores (with Jef Huisman). This collaboration is ongoing with the daily supervisor of one of the PhD students of Jef Huisman (Pedro Branco) on evolution of ecological stochiometric relationships in phytoplankton and zooplankton.
I am involved in the following courses and other teaching activities:
Bachelor programme Biology
Master programme Biological Sciences
For information or reprint requests, please do not hesitate to send me an e-mail!
60 Egas, M., Sabelis M.W. & Dieckmann U. (in press). Evolution of specialization and ecological character displacement along a gradient of plant quality. (Invited book chapter in: Elements of Adaptive Dynamics; eds. J.A.J. Metz, U. Dieckmann)
59 Sato, Y., Sakamoto H., Gotoh T., Saito Y., Chao J.-T., Seol K.-Y., Lee S., Egas M., & Mochizuki A. (in press). Patterns of reproductive isolation in a haplodiploid – strong postmating, prezygotic barriers among three forms of a social spider mite. Journal of Evolutionary Biology
58 Revynthi, A.M., Egas M., Janssen A., & Sabelis M.W. (in press). Prey exploitation and dispersal strategies vary among natural populations of a predatory mite. Ecology & Evolution
57 Branco, P., Egas M., Elser J.J. & Huisman J. (in press). Eco-evolutionary dynamics of ecological stoichiometry in plankton communities. American Naturalist
56 Revynthi, A.M., Janssen A., & Egas M. (2018). Gender-specific differences in cannibalism between a laboratory strain and a field strain of a predatory mite. Experimental and Applied Acarology 74:239-247, https://doi.org/10.1007/s10493-018-0232-4.
55 De Bruijn P.J.A., Sabelis M.W. & Egas M. (2017). Anti-predator responses to alarm pheromones in groups of mixed-size thrips larvae. Ethology 2017;00:1–9, https://doi.org/10.1111/eth.12600.
54 Knegt, B., Potter T., Pearson N., Sato Y., Staudacher H., Schimmel B.C.J., Kiers E.T. & Egas M. (2017) Detection of genetic incompatibilities in non-model systems using simple genetic markers: hybrid breakdown in the haplodiploid spider mite Tetranychus evansi. Heredity 118: 311-321, doi:10.1038/hdy.2016.103.
53 Sato, Y., Rühr P.T., Schmitz H., Egas M. & Blanke A. (2016) Age-dependent male mating tactics in a spider mite - a life history perspective. Ecology & Evolution, doi:10.1002/ece3.2489.
52 Sato, Y., Alba J.M., Egas M. & Sabelis M.W. (2016). The role of web sharing, species recognition and host-plant defence in interspecific competition between two herbivorous mite species. Experimental and Applied Acarology 70:261-274, DOI 10.1007/s10493-016-0079-5.
51 Swakman, V., Molleman L., Ule A. & Egas M. (2016). Reputation-based cooperation: empirical evidence for behavioral strategies. Evolution and Human Behavior 37:230-235, doi: 10.1016/j.evolhumbehav.2015.12.001.
50 De Bruijn, P.J.A., Egas M., Sabelis M.W. & Groot A.T. (2016). Context-dependent alarm signalling in an insect. Journal of Evolutionary Biology 29:665-671, doi:10.1111/jeb.12813.
49 Smallegange, I.M. & Egas M. (2015). Good for the group? Explaining apparent group-level adaptation. TREE 30:379-381, doi:10.1016/j.tree.2015.04.005.
48 Kant, M.R., Jonckheere W., Knegt B., Lemos F., Liu J., Schimmel B.C.J., Villarroel C.A., Ataide L.M.S., Dermauw W., Glas J.J., Egas M., Janssen A., Van Leeuwen T., Schuurink R.C., Sabelis M.W. & Alba J.M. (2015). Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities. Annals of Botany 115:1015-1051, doi:10.1093/aob/mcv054.
47 Tien, N.S.H., Sabelis M.W. & Egas M. (2015). Inbreeding depression and purging in a haplodiploid: gender-related effects. Heredity 114:327-332, doi: 10.1038/hdy.2014.106.
46 Sato, Y., Breeuwer, J.A.J., Egas M. & Sabelis M.W. (2015). Incomplete premating and postmating reproductive barriers between two parapatric populations of a social spider mite. Experimental and Applied Acarology 65:277-291. doi 10.1007/s10493-015-9878-3.
45 De Bruijn P.J.A., Sabelis M.W. & Egas M. (2014). Alternative models of familiarity and false claims concerning social recognition systems. Behavioral Ecology and Sociobiology 68:1563, doi: 10.1007/s00265-014-1798-4.
44 De Bruijn P.J.A., Sabelis M.W. & Egas M. (2014). Effects of kinship or familiarity? Small thrips larvae experience lower predation risk only in groups of mixed-size siblings. Behavioral Ecology and Sociobiology 68:1029-1035, doi: 10.1007/s00265-014-1715-x.
43 Sato, Y., Sabelis M.W. & Egas M. (2014). Alternative male mating behaviour in the two-spotted spider mite: dependence on age and density. Animal Behaviour 92:125-131, doi: 10.1016/j.anbehav.2014.03.032.
42 Sato, Y., Egas M., Sabelis M.W. & Mochizuki A. (2013). Male-Male Aggression Peaks at Intermediate Relatedness in a Social Spider Mite. Ecology and Evolution, doi: 10.1002/ece3.661.
41 Sato, Y., Sabelis M.W., Egas M. & Faraji F. (2013). Alternative phenotypes for male mating behaviour in the two-spotted spider mite. Experimental and Applied Acarology 61:31–41, DOI 10.1007/s10493-013-9673-y.
40 Egas, M., Kats R., van der Sar X., Reuben E., & Sabelis M.W. (2013) Human altruism by lethal group competition. Scientific Reports 3: 1373, doi: 10.1038/srep01373.
39 Molleman, L., Van den Broek E., & Egas M. (2013). Personal experience and reputation interact in human decisions to help reciprocally. Proceedings of the Royal Society London B Biological Sciences 280: 20123044, doi: 10.1098/rspb.2012.3044.
38 Sznajder, B., Sabelis M.W. & Egas M. (2012). How adaptive learning affects evolution: reviewing theory on the Baldwin effect. Evolutionary Biology 39: 301-310, doi: 10.1007/s11692-011-9155-2
37 Van Veelen, M., Garcia J., Sabelis M.W., & Egas M. (2012). Group selection and inclusive fitness are not equivalent; the Price equation vs. models and statistics. Journal of Theoretical Biology 299: 64-80.
36 Magalhaes, S., Blanchet E., Egas M. & Olivieri I. (2011). Environmental effects on the detection of adaptation. Journal of Evolutionary Biology 24: 2653–2662.
35 Konijnendijk, N., Mrosso H.D.J., Joyce D.A., Egas M., & Seehausen O. (2011) Community genetics reveal elevated levels of sympatric gene flow among morphologically similar but not among morphologically dissimilar species of Lake Victoria cichlid fish. International Journal of Evolutionary Biology, Article ID 616320, 12 pages, doi:10.4061/2011/616320
34 Sznajder, B., Sabelis M.W. & Egas M. (2011). Innate responses of the predatory mite Phytoseiulus persimilis to a herbivore-induced plant volatile. Experimental and Applied Acarology 54:125-138.
33 Tien, N.S.H., Massourakis, G., Sabelis M.W. & Egas, M. (2011). Mate choice promotes inbreeding avoidance in Tetranychus urticae. Experimental and Applied Acarology 54:119-124.
32 Sznajder, B., Sabelis M.W. & Egas M. (2011). The interplay between genetic and learned components of behavioural traits. Journal of Plant Interactions 6(2): 77-80.
31 Tien, N.S.H., Sabelis M.W. & Egas, M. (2011). Ambulatory dispersal in Tetranychus urticae: An artificial selection experiment on propensity to disperse yields no response. Experimental and Applied Acarology 53: 349–360.
30 Branco, P., Stomp, M., Egas, M. & Huisman, J. (2010). Evolution of nutrient uptake reveals a trade-off in the ecological stoichiometry of plant-herbivore interactions. American Naturalist 176: E162-E176.
29 Van Veelen, M., Garcia J., Sabelis M.W., & Egas M. (2010). Call for a return to rigour in models. Nature 467: 661.
28 Tien, N.S.H., Sabelis M.W. & Egas, M. (2010). The maintenance of genetic variation for oviposition rate in two-spotted spider mites: inferences from artificial selection. Evolution 64: 2547–2557.
27 Sznajder, B., Sabelis M.W. & Egas M. (2010). Response of predatory mites to a herbivore-induced plant volatile: genetic variation for context-dependent behaviour. Journal of Chemical Ecology 36: 680-688.
26 Bijleveld, A.I., Egas, M., Van Gils, J.A., & Piersma, T. (2010) Beyond the information centre hypothesis: communal roosting for information on food, predators, travel companions and mates? OIKOS 119: 277-285.
25 Tien, N.S.H., Sabelis M.W. & Egas, M. (2009). The heritability of defense and life-history traits in the two-spotted spider mite. Evolutionary Ecology Research 11: 1271-1281.
24 Magalhaes, S., Blanchet E., Egas M. & Olivieri I. (2009). Are adaptation costs necessary to build up a local adaptation pattern? BMC Evolutionary Biology 9: 182.
23 Kroon, A., Veenendaal R.L., Bruin J., Egas M. & Sabelis M.W. (2008). “Sleeping with the enemy” – Predator-induced diapause in a mite. Naturwissenschaften 95: 1195-1198.
22 Stomp, M., Van Dijk M.A., Van Overzee H.M.J., Wortel M., Sigon C.A.M., Egas M., Hoogveld H., Gons H.J. & Huisman J. (2008). The time scale of phenotypic plasticity, and its impact on competition in fluctuating environments. American Naturalist 172: E169-E185.
21 Egas M. & Riedl A. (2008). The economics of altruistic punishment and the maintenance of cooperation. Proceedings of the Royal Society London B Biological Sciences 275: 871-878.
20 Xue H., Egas M. & Yang X. (2007). Development of a positive preference-performance relationship in an oligophagous beetle: adaptive learning? Entomologia experimentalis et applicata 125: 119-124.
19 Rueffler C., Egas M. & Metz J.A.J. (2006). Evolutionary predictions should be based on individual-level traits. American Naturalist 168: E148-E162.
18 De Bruijn P.J.A., Egas M., Janssen A. & Sabelis M.W. (2006). Pheromone-induced priming of a defensive response in Western Flower Thrips. Journal of Chemical Ecology 32: 1599-1603.
17 Egas M., Sabelis M.W. & Dieckmann U. (2005). Evolution of specialization and ecological character displacement along a gradient of plant quality. Evolution 59(3): 507-520.
16 Kroon A., Veenendaal R.L., Egas M., Bruin J. & Sabelis M.W. (2005). Diapause incidence in the two-spotted spider mite increases due to predator presence, not due to selective predation. Experimental and Applied Acarology 35: 73-81.
15 Egas M. (2005). Evolution of specialization and ecological character displacement: metabolic plasticity matters. In: Current Themes in Theoretical Biology: A Dutch Perspective (eds. Th.A.C. Reydon, L. Hemerik), Springer, Dordrecht, pp 281-304.
14 Kroon A., Veenendaal R.L., Bruin J., Egas M. & Sabelis M.W. (2004). Predation risk affects diapause induction in the spider mite Tetranychus urticae. Experimental and Applied Acarology 34: 307-314.
13 Parvinen K. & Egas M. (2004). Dispersal and the evolution of specialisation in a two-habitat type metapopulation. Theoretical Population Biology 66: 233-248.
12 Egas M., Sabelis M.W., Vala F. & Lesna I. (2004). Adaptive speciation in agricultural pests. In: Adaptive Speciation, U. Dieckmann, J.A.J. Metz, M. Doebeli & D. Tautz (eds.), Cambridge University Press, Cambridge. Pp 249-263.
11 Vala F., Egas M., Breeuwer J.A.J. & Sabelis, M.W. (2004). Wolbachia affects mating and oviposition behavior of its spider mite host. Journal of Evolutionary Biology 17: 692-700.
10 Egas M., Dieckmann U. & Sabelis M.W. (2004). Evolution restricts the coexistence of specialists and generalists – the role of trade-off structure. American Naturalist 163: 518-531.
9 Egas M., Norde D.-J. & Sabelis M.W. (2003). Adaptive learning in arthropods: spider mites learn to distinguish food quality. Experimental and Applied Acarology 30: 233-247.
8 Magowski W., Egas M., Bruin J. & Sabelis M.W. (2003). Intraspecific variation in induction of feeding preference and performance in a herbivorous mite. Experimental and Applied Acarology 29:13-25.
7 Sabelis M.W., Van Baalen M., Pels B., Egas M. & Janssen A. (2002). Evolution of exploitation and defence in plant-herbivore-predator interactions. In: The Adaptive Dynamics of Infectious Diseases: In Pursuit of Virulence Management, U. Dieckmann, J.A.J. Metz, M.W. Sabelis & K. Sigmund (eds.), Cambridge University Press, Cambridge. Pp 297-321.
6 Egas M., Vala F. & Breeuwer J.A.J. (2002). On the evolution of cytoplasmic incompatibility in haplodiploid species. Evolution 56:1101-1109.
5 Chatzivasileiadis E.A., Egas M. & Sabelis M.W. (2001). Resistance to 2-tridecanone in Tetranychus urticae: effects of induced resistance, cross-resistance and heritability. Experimental and Applied Acarology 25:717-730.
4 Egas M. & Sabelis M.W. (2001). Adaptive learning of host preference in a herbivorous arthropod. Ecology Letters 4:190-195.
3 Van der Wal R., Egas M., Van der Veen A. & Bakker J. (2000). Effects of resource competition and herbivory on plant performance along a productivity gradient. Journal of Ecology 88:317-330.
2 Sabelis M.W., Van Baalen M., Bakker F.M., Bruin J., Drukker B., Egas M., Janssen A.R.M., Lesna I.K., Pels B., Van Rijn P.C.J. & Scutareanu P. (1999), The evolution of direct and indirect plant defence against herbivorous arthropods. In: Herbivores: between Plants and Predators, H. Olff, V.K. Brown & R.H. Drent (eds), Blackwell Scientific Publications, Oxford. Pp 109-166.
1 Sabelis M.W., Van Baalen M., Bruin J., Egas M., Jansen V.A.A., Janssen A. & Pels B. (1999), The evolution of overexploitation and mutualism in plant-herbivore-predator interactions and its impact on population dynamics. In: Theoretical Approaches to Biological Control, B.A. Hawkins & H.V. Cornell (eds.), Cambridge University Press, Cambridge. Pp 259-282.
Menken S. & Egas M. (2002). Nieuwe soort zoekt nieuwe soort. Natuur & Techniek 70 (3): 36-39.
Egas M. (2002). Spintmijten leren foerageren - nieuw licht op de evolutie van waardplantspecialisatie en gastheerrasvorming. Entomologische Berichten 62(3-4): 66-72.
Egas M., Dieckmann U. & Sabelis M.W. (2004). Evolution restricts the coexistence of specialists and generalists - the role of trade-off structure. IIASA Interim Report IR-04-004 , available at http://www.iiasa. ac.at/Research/ADN/Publications.html .
Egas M. & Riedl A. (2005). The economics of altruistic punishment and the demise of cooperation. Tinbergen Institute Discussion Paper 05065, available at http://www.tinbergen.nl/discussionpapers/05065.pdf.