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Almost all animal and plant species inhabiting the earth today are anisogamous. That is, there are only two dominant biological sexes (except the intersex individuals), and we define each sex based on the size and the quantity of the gametes they produce. Females produce few large gametes (i.e., egg, ovum), while males produce numerous comparatively tiny gametes (i.e., sperm, pollen).
We still do not understand why anisogamy has evolved in the first place. Why the number and size disparity between the sexes? Why not more than two sexes? Why not just one type of gamete? Why is anisogamy so prevalent except for only some fungi and unicellular organisms? Beyond quenching our curiosity on the genesis of life on earth, finding answers to these questions can help us better grasp many subsequent events, such as speciation, physiological differences between sexes, and the development of social constructs relating to sexes, sexuality, and gender.
I developed an agent-based model with NetLogo to conduct theoretical experiments that take us to the world of our hypothetical marine ancestor (e.g., a proto-algae) that inhabited the oceans at the early stages of life on earth. The adult individuals of this ancestor are two pseudo-sexes with the same reproductive strategy. This strategy, called isogamy and observed in some fungal species today, means both mating types produce gametes of similar size and quantities.
My model allows us to explore possible evolutionary pathways that may have led to the emergence of anisogamy as an evolutionarily stable strategy (ESS) within this early isogamous ancestor.
I published a couple conference papers on my anisogamy model and I am currently working on an extended publication on this model.
An early paper that explained how I conceptualized this project but included a much more crude early version of the anisogamy model:
Aslan, U., & Wilensky, U. (2016). Restructuration in Practice: Challenging a Pop-Culture Evolutionary Theory through Agent Based Modeling. In Proceedings of the Constructionism Conference, Constructionism 2016 (pp. 230-238). http://ccl.northwestern.edu/2016/Aslan-Wilensky2016.pdf.
A later paper that included the first version of my model and focused on the process of generating such theoretical computational models as thought experiments:
Aslan, U., Dabholkar, S., & Wilensky, U. (2017). Developing Multi-agent-based Thought Experiments: A Case Study on the Evolution of Gamete Dimorphism. In J. A. Rodriguez-Aguilar, & G. Sukthankar (Eds.), Autonomous Agents and Multiagent Systems - AAMAS 2017 Workshops, Revised Selected Papers (pp. 51-65). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 10642 LNAI). Springer Verlag. https://doi.org/10.1007/978-3-319-71682-4_4
I also hope to plan to publish the pre-print of our full paper soon.