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Reproduction General Zoology LS2014 11 February 2011 Following Hickman et al. 2011 Integrated Principles of Zoology, 15 th ed., McGraw-Hill, NY. Ch. 7.

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Presentation on theme: "Reproduction General Zoology LS2014 11 February 2011 Following Hickman et al. 2011 Integrated Principles of Zoology, 15 th ed., McGraw-Hill, NY. Ch. 7."— Presentation transcript:

1 Reproduction General Zoology LS February 2011 Following Hickman et al Integrated Principles of Zoology, 15 th ed., McGraw-Hill, NY. Ch. 7 pp , , Donald Winslow

2 Types of reproduction asexual  binary fission  budding  ameiotic parthenogenesis sexual  dioecy (separate sexes)‏  monoecy (hermaphroditism)‏  meiotic parthenogenesis, haplodiploidy  conjugation

3 Generalized sexual lifecycle femal e male Ovum sperm (gametes, 1N)‏ meiosis 2N fertilizatio n zygot e (2N)‏ embryo development

4 Figure 07.1 From Hickman et al (13 th ed.)‏

5 The cost of sexual reproduction Half of all alleles are thrown away during meiosis! Males can’t produce eggs, so why have sons?

6 From Hickman et al (13th ed.)‏

7 The function of sexual recombination Increased variability—new combinations of alleles. Sexual populations better able to adapt to changing environment. (Group selection)‏

8 Somatic cells and germ line cells Germ line cells give rise to the gametes.  Gametogenesis (spermatogenesis & oogenesis)‏  Oogenesis results in 3 polar bodies for each ovum. Somatic cells give rise to all the tissues of the body.

9 Mechanisms of sex determination Y chromosomes  In humans, presence of Y induces male development. Ratio of X chromosomes to autosomes  In Drosophila flies, ratio of X chromosomes to autosomes determines whether male or female. Temperature  In reptiles, temperature of nest often determines sex ratio of hatchlings.

10 Levels of maternal physiological investment Ovipary  Development takes place after female deposits egg. Ovovivipary  Development takes place within mother’s body, but without nutritional investment from mother. Vivipary  Development takes place within mother’s body, with nutritional investment from mother.  Example: placental mammals

11 Karen Bays in gestation


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