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Reproductive strategies for Survival. How many, and how often?. Eggs or liveborn young?. Oviparity. Viviparity. Types of viviparity are recognised by the nutrient source for the developing embryo. Activities.
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Viviparity Types of viviparity are recognised by the nutrient source for the developing embryo
Activities Glossary: r selection, K selection, fecundity, oviparity, viviparity, amniote, placenta, mortality, monotreme Quick check questions: pg 383, 387.
Case studies – 1. Australian Mallee Fowl • Male invests energy into nest building – incubation mound made of rotting plant matter • Female invests energy into laying 12 to 24 eggs at once • Male incubates • Chicks hatch, do not require further care
Case studies – 2. Emu • Polyandrous • Male is caregiver • He builds nest, incubates eggs, guards young • Female lays eggs and leaves to mate again
Australian Marsupials • Placental mammals (not marsupials) have a long period of uterine development • In contrast, marsupials have a short period within the uterus, and a long period developing in the pouch • TURN TO PAGE 391 IN YOUR TEXT BOOK
Australian Marsupials – arrested development • Kangaroos and wallabies can suspend development within the uterus • If kangaroo conceives while young is in pouch, she stops uterine development until pouch young is off the nipple in the pouch.
Activities Glossary: cephalopod, marsupial, placental mammal Quick check pg 393