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
Spawn event
Fertilised egg nourishes larva with yolk
Larva hatches, floats around in ocean
Juvenile fish
Sexually mature adult fish

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
Reproductive strategies we’ve already looked at
New reproductive strategies
Type of reproduction (asexual/sexual)
Gender systems (separate male/female, hermaphrodite)
Mode of fertilisation (internal/external)
Mating system (monogamy, polygamy, promiscuity)
Number of offspring (K selection, r selection)
Place of development and nutrition for embryo (oviparity, viviparity)
Investment of care into offspring (one parent, both parents, neither parent)

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
Harem polygyny
Serial polygyny
One dominant males lives with a group of females.
Mates with each of them during the mating season.
Examples: Magpies, wood mouse, Elephant seals
One male attracts passing females for mating
Males must advertise themselves
In bird species, male is often highly decorated to attract female
Male usually does not care for young
Examples: Lyrebird, Bowerbird, Peacock, Horseshoe bats

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