1. Types of Sexual Reproduction

2. Vocabulary Conjugation, hermaphrodite Stamen, filament, anther, pollen
Pistil, stigma, style, ovary, petals, petals, sepals, pollination
external fertilization, internal fertilization

3. Conjugation
Some organisms that reproduce asexually through binary fission can also reproduce sexually by conjugation.
Conjugation occurs when two unicellular organisms transfer or exchange some of their genetic material.
Some bacteria and certain Protists like Paramecium
Example: bacteria like E.coli one cell copies an extra piece of DNA (called a plasmid) and donates the plasmid copy to another cell

4. Autogamy “Auto” means “self”
Autogamy means an organism can fertilize itself
Hermaphrodites are organisms that produce both male and female sex cells within the same individual.
Hermaphrodites occur in plants and some animals that are attached to one location and/or rarely come in contact with other individuals of their species.
Eg many aquatic organisms (sponges and barnacles), Earthworms, flowers
Although autogamy is similar to asexual reproduction, in that there is no input of genetic diversity from a partner, the recombination of chromosomes from the male and female gametes results in offspring with slightly altered genetic information, which can therefore look phenotypically different from their parents. Most plants and earthworms reproduce by autogamy. It is sometimes possible for hermaphrodites to reproduce with other hermaphrodites. In this case, genetic diversity does increase within the population.

5. Compare Autogamy to Asexual Reproduction
No input of genetic diversity from a partner.
But the recombination of chromosomes from the male and female gametes results in slightly genetically different offspring
It is possible for hermaphrodites to reproduce with other hermaphrodites. In this case, genetic diversity does increase within the population.

6. Allogamy
Allogamy is the fertilization of an egg from one individual with the sperm of another (cross-fertilization).
Occurs in most complex animals and some plants
Eg. Conifers such as pine and fir trees have separate male and female cones on the same plant.
Poplar trees have separate sexes on separate plants.

7. Fertilization
Fertilization is the process in which the nuclei of the male and female gametes fuse together to produce a single cell called a zygote.
Sperm cells have long tails “flagella”.
Egg cells are much bigger and lack flagella. What does the presence or absence of flagella say about the cells motility?

8. Types of Fertilization: External Fertilization
gametes meet outside of the parents
The female deposits unfertilized eggs and males release sperm over the eggs.
Occurs in aquatic or moist environments so gametes don’t dry out. (sperm can only swim in a wet environment)
Common in fish and amphibians
Both gametes and developing young are vulnerable to environment and predators.
Large numbers of eggs produced to ensure enough mature offspring survive.
fertilization (the exceptions are aquatic mammals, sharks, and some other special types of fish).
External fertilization usually occurs among organisms living in aquatic environments. Land animals generally have specialized organs for internal fertilization.

9. Advantages of External Fertilization:
Results in the production of a large number of offspring
Easier to find mates as the gametes released can drift (wind, water etc).
More genetic variation

10. Disadvantages of External Fertilization
Environmental hazards such as predators reduce the change of surviving into adulthood.
Large amounts of gametes go unfertilised and wasted.
Not guaranteed that sperm will come in contact with eggs
Greater chance of desiccation (drying out) of gametes/zygotes.

11. Internal Fertilization
Gametes meet inside female’s body
Occurs in mammals, reptiles, birds, and some types of fish 
Provides more nutrient investment into a single egg
Provides a wet environment for the sperm and the egg and protection from other environmental conditions.
Eg. Temperature regulation
Requires specialized structures to ensure meeting of gametes
Parents must care for young during gestation
All land dwellers need to fertilize this way because sperm still prefer swimming
Need specialized structures. Penis

12. Advantages: Increase chance gametes meet
greater change of successful fertilisation
More protection against outside environments and predators, and therefore a higher chance of surviving until birth.
More selective of their mates 
Less chance of desiccation of gametes

13. Disadvantages
Harder to bring both male and female into intimate contact
Limited amount of offspring being produced at any given time. 
Parents must care for young through out gestation

14. Disadvantages of Internal Fertilization
Complex courtship and mating behaviours
Parents (usually female) must care for the young throughout gestation or until the eggs hatch
Specialized structures are required to ensure the meeting of gametes

15. Disadvantages of External Fertilization
Large number of gametes must be produced to ensure mature offspring survive
Seasonal due to the delicate nature of the gametes
Many zygotes are produced but only a few survive due to predation and environmental conditions

16. Check your understanding
How does the process of fertilization occur?
What is needed for fertilization to occur?
Describe the different forms of fertilization and give an example of an organism that uses them.

17. Internal and External Fertilization
Name an organism for each method
How is internal fertilization an advantage over external?
Why do you think organisms that reproduce using external fertilization release a large number of eggs and sperm?