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Reproductive strategies for survival

Reproductive strategies for survival. Sex on the Reef and promiscuity of organisms. Great Barrier Reef. Stretches about 2300km along the Queensland coast. Contains many reefs, of differing types Platform Fringing Barrier Ribbon. Coral. Colonial animals, called POLYPS

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Reproductive strategies for survival

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  1. Reproductive strategies for survival Sex on the Reef and promiscuity of organisms

  2. Great Barrier Reef • Stretches about 2300km along the Queensland coast. • Contains many reefs, of differing types • Platform • Fringing • Barrier • Ribbon

  3. Coral • Colonial animals, called POLYPS • Lives in calcerious cup • Sticks out tentacles to feed • Polyps are carnivorous

  4. Reef zones • Shallow waters/ reef flats • Find rays and sharks • Other light-dependent organisms • Warm waters • Deeper “barrier” habitats • Likely to find more plentiful small fish • Turtles • Octopus • Cooler water, less light available

  5. Broadcast spawning • Simultaneous release of eggs and sperm into water • Usually occurs in areas with some current to distribute gametes • Happens in many fish species, as well as the coral polyps

  6. Broadcast spawning continued • Current takes fertilised eggs away from reef (and predators) • Floating eggs are called PELAGIC eggs Boxfish mate in pairs by meeting up and releasing their gametes together Large groups broadcast spawn together. This is called a MASS SPAWNING event

  7. Other broadcast spawners • Not only reef fish • Flood plain river fish (needs to be quick) • Open ocean fish such as the mackeral

  8. Energy needs for broadcast spawning • High energy needs • Production of many gametes • However, no energy required for care of young

  9. Demersal spawning • Demersal eggs do not float • Female lays eggs in nest or crevice • Male drops sperm on them • Take care or protect eggs until hatching • Less eggs = less energy used, but care of eggs = more energy used • Higher chance of offspring survival than broadcast spawning Clownfish reproduce using demersal spawning Despite impressions given by Finding Nemo, clownfish receive no parental care after hatching

  10. Activities Glossary: polyps, broadcast spawning, mass spawn, demersal spawning, pelagic Quick check questions pg 376

  11. Reproductive strategies

  12. Mating systems • Mating systems refer to the number of partners and therefore sexual encounters an organism experiences

  13. Monogamy – just us two! • Pair bonds (like most humans) • >90% of bird species are monogamous • Few mammalian monogamous species • Usually occurs when care of young is required by both parents • Defending nest/home • Incubation of eggs (mostly Aves) • Feeding offspring

  14. Helpless baby monogamists • Young monogamists are usually born helpless – blind, hair/featherless, unable to fend for themselves Parrot hatchlings Newborn gibbon

  15. Polygamy – many partners • Male or female may have many partners • One parent can ensure survival of young • Polygyny – one male has many female partners in one season • Polyandry – one female has many male partners in one season Poly = many gyny = women andry = men

  16. Polygyny – many females

  17. Bowerbird – a case study • Satin Bowerbirds build nests which are covered in blue found objects • Also will sing and dance in front of his bower when a female walks by • If she is impressed, she enters the bower and the pair mate • Female mates with only one male a season • Male mates with as many females as he can impress with his display • All male’s energy is put into creating, maintaining and presenting his bower • Few will father young

  18. Lekking • Serial polygyny sometimes involves LEKKING • Males all gather together and display for passing females • May be visual or vocal displays, including violent displays

  19. Polyandry – many men • Rare in nature • Female mates with more than one male in a breeding season • Female often more ornate than male • Female cassowary mates with a male, lays a clutch of eggs in a nest he’s made, then leaves him to incubate the eggs and care for the young, while she looks for another mate. • Marmosets also exhibit polyandry Cassowary Marmoset young

  20. Promiscuity • Males and females in a social group engage in indescriminate, multiple, numerous matings every season. • All males approximately equally likely to produce offspring • More likely to occur in males, as the production of sperm is relatively low-energy, whereas the production of an egg requires more energy

  21. Activities Glossary: monogamy, polygamy, polygyny, polyandry, harem polygyny, serial polygyny, lekking, promiscuity Quick Check questions pg 381

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