Chapter XIII Wholly Virgin

1. Chapter XIII Wholly Virgin * compiled by Megan Ponce Aaron Wong May Kim Expanded concepts surrounding the *bdelloid rotifer with respect to Olivia Judson’s Dr. Tatiana’s Sex Advice to All Creation

2. Thesis Statement While numerous species reproduce asexuality in nature, many scientists agree that sex is necessary for long term evolution. The Bdelloid rotifer provides evidence that exclusive parthenogenesis is not an evolutionary dead end. 2

3. Definitions: • Parthenogenesis: Reproduction with out sex. • Sex: The recombination of different genetic DNA from different organisms by crossing over or by fertilization or by conjugation. • Apodictic: Reproduction with specialized tissues but not necessarily fertilization. • Haplotype: set of alleles that determine different antigens but are closely linked on one chromosome and inherited as a unit 3

4. Are men really necessary? Usually, but not always. Common name: Bdelloid rotifer Scientific name: Philodina roseola parthenogenetic chaetonotid gastrotichs aphid Lay eggs that develop into genetically identical embryos whiptail darwinulid ostracods 4 No meiosis!

5. How old is ancient? 85 Million Years 3 week lifespan = 1.5 billion generations Fossil record goes back 40 million The rest is based on molecular evidence 5

6. Evidence of the “evolutionary scandal” Sexual and asexual rotifers exist Researchers looked at similar genes in many species of rotifer Asexual gene copies differed significantly from sexual gene copies 6

7. What studies show • Bdelloid rotifer • Chromosomes lack homologous pairs • Chromosomes no segregation • Each copy of a gene belongs to one of two lineages • Lineages differ by 50% • Sexual Species • Homologous pairs • Two sets of chromosomes, segregated by haplotypes 7

8. Other “asexuals” discredited asexual discredited asexual * chaetonotid gastrotichs * darwinulid ostracods *males and hermaphrodites found facultative asexual time will tell aphid whiptail 8

9. Pattern of molecular evolution in asexual species Asexuals may simply have slow rates of mutation Cloning does not necessarily create identical organisms Mutations that accumulate are selected out 9

10. Why sex should be more favorable • Homologous genes repair mutations in DNA • Genetic recombination = most favorable traits • Parental care • Eliminate harmful mutations • Higher chance of parasites/pathogens resistance 10

11. Why Bdelloid rotifer is asexual. • The Bdelloid rotifer can live in distilled water, seawater, and every salinity variation. • She lives in temperatures between 10 and 30 degrees Celsius. • The genome is very flexible and may contribute to the successes of the Bdelloid rotifer. 11

12. Muller’s ratchet and Kondrashov'shatchet Muller's Ratchet The theory that in small populations: Harmful mutation rate > natural selection removes mutations Kondrashov's Hatchet The theory that in large populations: Harmful mutations build up, mutations die out 12

13. Endosymbionts Endosymbiont: The symbiont lives within the body of the host. In asexual organisms, an endosymbiont can increase the likelihood of survival. 13

14. Epigenetic effects • Epigenetic: A chain of developmental processes in epigenesist that lead from genotype to phenotype after the initial action of the genes. In the case of Myzus persicae an aphid, the heterozygous have the a resistance to certain pesticides, but when they are homozygous recessive they lose the resistance. This is caused by a change of the process of epigenesist. 14

15. How to escape the red queen Diversity - 360+ species discovered Mutations = neutral Run away from parasites 15

16. Anhydrobiosis -Escape method from parasites In dormant state, can be flushed away, blown away by wind, or even outlast parasites A type of Cryptobiosis: the reversible cessation of metabolism under extreme environmental conditions 16

17. Conclusion • There is strong evidence that the Bdelloid rotifer is an asexual that has had no sexual gene exchange for over 85 million years. • Asexuality can be a way for a species to build up mutations that may allow them to evolve at an accelerated rate, which can be an advantage over the sexual species, but more research is needed to understand this better. 17

18. Resources Andrea Gandolfi*,, Ian R. Sanders, Valeria Rossi* and Paolo Menozzi (2003). Evidence of Recombination in Putative Ancient Asexuals. Society for Molecular Biology and Evolution. Retrieved 16 April 2005 from http://mbe.oupjournals.org/cgi/content/full/20/5/754. C. William Birky, Jr (2004). Bdelloid rotifers revisited. The National Academy of Sciences. Retrieved 16 April from 2005 http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&p ubmedid=14981265 Hales, D, Sunnucks, P, Wilson, A. (2003). Heritable genetic variation and potential for adaptive evolution in asexual aphids. Biological Journal of the Linnaean Society, 79, page 115-135. Judson, Olivia (2003). Dr. Tatiana’s Sex Advice to All Creation. Henry Holt and Company: New York. Pages 212-232. 18

19. Resources Martens K, Rossetti G, Horne DJ (2003). Koninklijk Belgisch Instituut voor Natuurwetenschappe. Retrieved 16 April 2005 from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pu bmed&dopt=Abstract&list_uids=12713746 Schon I, Martens K (2003). No slave to sex. Royal Belgian Institute of Natural Sciences. Retrieved 14 April 2005 from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pu bmed&dopt=Abstract&list_uids=12737661 Tunnacliffe A, Lapinski J (2003). Resurrecting Van Leeuwenhoek's rotifers: a reappraisal of the role of disaccharides in anhydrobiosis. Institute of Biotechnology, University of Cambridge. Retrieved 16 April 2005 from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pu bmed&dopt=Abstract&list_uids=14561331 Welch, Mark, David B (2004). Mark Welch, and Matthew Meselson. Cytogenetic evidence for asexual evolution of bdelloid rotifers. The National Academy of Sciences. Retrieved 15 April 2005 from http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&p ubmedid=14747655 18

20. Resources: list of figures Ahydrobiosis. Retrieved 22 May 2005 from http://users.unimi.it/ricci/html/anhydro.htm Aphid. Retrieved 21 May 2005 from http://www.nysaes.cornell.edu/ent/factsheets/images/gpa-nymph1b.jpg Bdelloid. Retrieved 25 May 2005 from http://www.sciencenews.org/articles/20000520/fob6.asp Bdelloid rotifer. Retrieved 20 May 2005 from http://www.sciencenews.org/articles/20030628/a3723_2645.jpg Bdelloid rotifer. Retrieved 25 May 2005 from http://www.treknature.com/images/photos/338/bdelloid__rotifer.jpg Darwinulid ostracods. Retrieved 23 May 2005 from http://www.sciencenews.org/articles/20030628/a3723_1859.jpg Evolution. Retrieved 25 May 2005 from http://lifewithalacrity.blogs.com/photos/uncategorized/evolution.jpg Mexico Whiptail. Retrieved 24 May 2005 from http://www.arts.arizona.edu/herp/asco2.jpg

21. Resources: list of figures Ostracod shells. Retrieved 22 May 2005 from http://www2.una.edu/microaquarium/images/Arthropods/Crustaceans/ ostracods/OstracodShells1943cm.jpg Red Queen. Retrieved 24 May 2005 from http://www.funkervogt.net/News/redqueen.gif Red Queen Software. Retrieved 24 May 2005 from http://www.redqueensoftware.com/images/Index%20page_r02_c3.gif Rotifer. Retrieved 21 May 2005 from http://fs6.depauw.edu:50080/~cfornari/images/roti001b.gif Rotifer. Retrieved 22 May 2005 from http://www.microimaging.ca/rotifer1.jpg Rotifer. Retrieved 25 May 2005 from http://www.microimaging.ca/rotifer2.jpg Rotifera. Retrieved 24 May 2005 from http://www.ucmp.berkeley.edu/phyla/rotifera/rotiferclad.gif