Why Sex Persists

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• A New Mexico whiptail blends into sand at Rio Grande Nature Center State Park

  Funknendai

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  Incorporated into an explanatory animation; presentation may include cropping, labels and overlays.

• Paardenbloem (Taraxacum officinale) 26-04-2020. (actm.) 01

  Agnes Monkelbaan

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  Incorporated into an explanatory animation; presentation may include cropping, labels and overlays.

• Saccharomyces cerevisiae SEM

  Mogana Das Murtey and Patchamuthu Ramasamy

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  Incorporated into an explanatory animation; presentation may include cropping, labels and overlays.

• Chlamydomonas6-1

  Dartmouth Electron Microscope Facility, Dartmouth College

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  Incorporated into an explanatory animation; presentation may include cropping, labels and overlays.

• Kelp forest at Strawberry Rocks PC013138

  Peter Southwood

  View original source ↗CC BY-SA 3.0

• Potamopyrgus antipodarum 01

  H. Zell

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• Бделлоидные коловратки

  Andrei Savitsky

  View original source ↗CC BY 4.0

Research references

Selected sources from the episode’s research and scientific figures.

1. Eme et al., “The evolution of eukaryotic cell complexity,” PLOS Biology (2024), including Box 1 consensus reconstruction ↗
2. Ramesh, Malik and Logsdon, comparative meiotic-gene evidence in *Giardia* (2005) ↗
3. Archaeal fusexins and the ancestry of eukaryotic gamete fusion, Nature Communications (2022) ↗
4. Rad51/Dmc1 recombinase-family phylogeny, primary article ↗
5. OpenStax Biology 2e, “The Process of Meiosis” ↗
6. OpenStax Biology, “Sexual Reproduction” and life-cycle comparison ↗
7. Lehtonen, Jennions and Kokko, components and conditions of the costs of sex ↗
8. Meirmans, Meirmans and Kirkendall, costs and maintenance of sex ↗
9. Sharp and Otto, contemporary review of sex and recombination ↗
10. López-Villavicencio et al. 2013 ↗
11. Jain 2008, finite-population ratchet theory ↗
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC4855304/ ↗
13. NCBI BioProject PRJNA308843 ↗
14. DOI: 10.1086/599080 ↗
15. Gibson, Delph and Vergara, periodic selection ↗
16. Dryad 10.5061/dryad.77v1s92 ↗
17. Paczesniak et al. 2019 ↗
18. Eawag accepted manuscript ↗
19. paper record ↗
20. DOI: 10.1111/jeb.14237 ↗
21. Neiman et al. 2009, asexual lineage-age review ↗
22. Schwander and Crespi 2009, phylogenetic/neutral-model critique ↗
23. Öztoprak et al. 2025, ancient asexual mite ↗
24. 2021 ↗
25. https://pmc.ncbi.nlm.nih.gov/articles/PMC9710870/ ↗
26. 2020 ↗
27. Wilson et al. 2024 review ↗
28. Luo et al. 2024 ↗
29. Xu et al. 2026 ↗
30. Williamson et al. 2025, “A robustly rooted tree of eukaryotes reveals their excavate ancestry” ↗
31. April 2026 independent-marker preprint ↗
32. item page ↗
33. 2016 review ↗
34. 2014 review ↗
35. 2019 review ↗
36. OpenStax Biology 2e, representative protist cycles ↗
37. Nature paper record ↗
38. Morran, Parmenter and Phillips 2009 ↗
39. Gray and Goddard 2012 ↗
40. Noël et al. 2019 ↗
41. Colpitts et al. 2017 ↗
42. Hollister et al. 2015, repeated plant transitions ↗
43. Blasco-Costa et al., formal description of *A. winterbourni* ↗
44. Feijen et al. 2022, parasite phylogeography and cryptic species ↗
45. King et al. 2009, geographic mosaic ↗
46. King et al. 2011, hotspot/coldspot replication ↗
47. 2016 primary record ↗
48. ETH record for the 2009 study ↗
49. research and publication page ↗
50. X status 1866215018452443470 ↗
51. Dryad 10.5061/dryad.2ngf1vhnw ↗
52. “The effects of sex on extinction dynamics of *Chlamydomonas reinhardtii* depend on the rate of environmental change,” Journal of Evolutionary Biology 36:1783–1795 ↗
53. Nature paper ↗
54. Science Advances paper ↗
55. Zenodo 6334766 ↗
56. open author/version-of-record PDF ↗
57. preprint DOI ↗
58. “Bdelloid creating a circular stream of particles” ↗
59. Figshare 10.6084/m9.figshare.26863594.v1 ↗
60. Burki et al. 2020, “The new tree of eukaryotes” review ↗
61. He et al. 2026 ↗
62. Earth-system productivity/color model, 2026 ↗
63. *Potamopyrgus antipodarum* 01 ↗
64. institutional landing page ↗
65. atriophallophorus 2020 ↗
66. X status 1221979817563717632 ↗
67. *Philodina* sp., Class Bdelloidea ↗
68. X status 1654410846645133317 ↗
69. Chlamydomonas TEM 17 ↗
70. item page ↗
71. item page ↗
72. a 2022 Communications Biology article ↗
73. “Mating & Tetrad Separation Of *Chlamydomonas reinhardtii*” ↗
74. Commons item ↗
75. Commons diagram ↗
76. mouse spermatocyte item ↗
77. plant cell item ↗
78. Commons “Meiose (meiosis)” ↗
79. “Meiosis main steps” ↗
80. Figshare collection 10.6084/m9.figshare.c.3893857 ↗
81. https://commons.wikimedia.org/wiki/File:Philodina_sp._(Class%CB%90_Bdelloidea)_-_Rotifera.jpg ↗
82. https://commons.wikimedia.org/wiki/File:Meiose_(meiosis).jpg ↗
83. https://x.com/i/status/1866215018452443470): ↗
84. https://x.com/i/status/1221979817563717632): ↗
85. https://x.com/i/status/1654410846645133317): ↗
86. DOI: 10.1038/nature17143 ↗
87. DOI: 10.1126/science.1206360 ↗
88. DOI: 10.1126/sciadv.adc8829 ↗

Music

• Meditation From The Star Orion
  OctahedronMusic · Envato Elements