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Primer on Parthenogenesis & some other interesting variations in vertebrate reproduction Robin Wright

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Presentation on theme: "Primer on Parthenogenesis & some other interesting variations in vertebrate reproduction Robin Wright"— Presentation transcript:

1 Primer on Parthenogenesis & some other interesting variations in vertebrate reproduction Robin Wright

2 A b a B M1 M2 (P1 P2) (P3 P4) Haplotype M1 M2 Meiosis or Mitosis Development Parthenogenesis egg Gynogenesis egg M1 M2 M1 M2 M1 M2 P1 P2 P1 or P2 M1 M2 Paternal genome eliminated Meiosis Fertilization Development M1 M2 Hybridogenesis egg M1 P1 M1 or M1 P3 P3 P4 P3 or P4 M1 P3 or M1 P4 M1 P2 M1 P2 Fertilization Meiosis: Paternal genome eliminated Development Some Variations in Vertebrate Reproduction Homologs

3 Failure of Meiosis II Meiosis I Diploid Maternal Cell Mitosis No change in chromosome number; Egg is genetic clone of mother DNA replication Meiosis I Meiosis II ABCD Fusion of egg& second polar body Meiosis I Meiosis II Mitotic Duplication of Chromosomes after Meiosis Possible Egg Genotypes = Possible Genotypes of Parthenogenetic Offspring Production of Parthenogenetic Eggs metaphase

4 Failure of Meiosis II Meiosis I Diploid Maternal Cell Mitosis No change in chromosome number; Egg is genetic clone of mother DNA replication A+CA+DB+CB+D Meiosis I Meiosis II ABCD Fusion of egg& second polar body Meiosis I Meiosis II Mitotic Duplication of Chromosomes after Meiosis Possible Egg Genotypes = Possible Genotypes of Parthenogenetic Offspring Production of Parthenogenetic Eggs metaphase

5 What if parthenogenesis occurred in mammals? X Failure of Meiosis II Meiosis I X Diploid Maternal Cell X DNA replication This example is theoretical. Parthenogenesis has not been observed in mammals, probably because of imprinting requirements. Because female mammals are X X, only female offspring would be produced by parthenogenesis. You may also want to go through meiosis in a male to illustrate that the sperm will carry either an X or a Y chromosome, but not both.

6 Sex Determination & Parthenogenesis Diploid Maternal Cell Z W DNA replication Failure of Meiosis II Meiosis I Z W ZZ WW ZZ All male or all female offspring produced Meiosis I ZZWW ZW Meiosis II ZZ WW Fusion of ovum & second polar body Meiosis I ZZWW ZZ Z W Meiosis II ZZ WW Mitotic Duplication of Chromosomes after Meiosis

7 Sex Determination & Parthenogenesis Diploid Maternal Cell Z W DNA replication Failure of Meiosis II Meiosis I Z W ZZ WW ZZ All male or all female offspring produced Meiosis I ZZWW ZW Meiosis II ZZ WW Fusion of ovum & second polar body Meiosis I ZZWW ZZ Z W Meiosis II ZZ WW Mitotic Duplication of Chromosomes after Meiosis X Failure of Meiosis II Meiosis I Hypothetical mammal

8 Diploid Maternal Cell Z W DNA replication Handout: Sex Determination in Parthenogenesis X Meiosis I Hypothetical mammal Meiosis I Z W Meiosis I Z W Meiosis I Z W

9 M1 M2 Clone of Mother Mitosis Development egg Parthenogenesis in all Female Species Failure of Meiosis II M1 M2 Offspring inherits half of the mother’s alleles: Half-Clone Development egg M1 M2 Offspring inherits half of the mother’s alleles: Half-Clone Development egg Fusion of Egg & Second Polar Body or chromosome duplication before first mitotic division in development Homologs Duplication of chromosomes before meiosis starts M1 M2 Clone of Mother Development egg


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