REPRODUCTION  Species need to reproduce in order to survive  Not all individuals of that species may reproduce-remember, evolution said that only the “fittest” survive to pass on those “fit” genes

Two kinds of reproduction-  Remember?……  ASEXUAL reproduction: one parent, offspring is genetically identical to parent  Examples are binary fission in unicellular organisms, runners in spider plants

Advantages of asexual reproduction  Faster than sexual reproduction, and no other organism is necessary  No variation…..if organism is perfectly adapted for that environment, exact copies will also be perfectly adapted  No variation is also the DISADVANTAGE- if the environment changes, there may be no chance of the species surviving in that new environment- what if the peppered moth had only one version?

Cell division-  In Asexual Reproduction is MITOSIS (or a similar process)-  Makes exact copies- CLONES- (except now we know about mutations)

And SEXUAL Reproduction  TWO parents, offspring is genetically different from either parent  Adds variation to a species

GAMETES  Are produced after MEIOSIS  Gametes fuse during FERTILIZATION  Fertilized egg- ZYGOTE-undergoes rapid mitosis and differentiation to become-  An EMBRYO

CONJUGATION  Occurs in Protists and some algae  Two organisms exchange genetic material to create a new variation, although they don’t create another organism until they undergo binary fission.

‘Member Plant Reproduction?  Flowers Are the reproductive organ of anthophytes (angiosperms)  Cones are the reproductive organs of gymnosperms  Other plants also use sperm and egg in a different strategy

But, let’s get to the animals-  GAMETES (AKA…..germ cells)– sperm and egg (ovum)- are produced in the gonads-testes and ovaries  Some organisms- worms and snails-have both testes and ovaries, but they exchange sperm packets

FERTILIZATION  Can be INTERNAL, where sperm and egg meet inside the body of the female  Occurs in land animals-insects, turtles, humans  Can be EXTERNAL, where the sperm and egg meet outside the body of the female  Usually occurs in animals that live in water (Remember: those sperm HAVE TO swim)-fish, frogs

MATING BEHAVIORS/Pollination Strategies  Insure that the organism is the same species (fish look the same even to fish)  Insures that the egg will be fertilized at the correct time  Insures only the “fittest” reproduce

DEVELOPMENT  Can be INTERNAL- inside the body of the female, partially (marsupials) and fully (placental mammals)  Can be EXTERNAL- outside the body of the female, in eggs with no shells (fish), soft shells (turtles), hard shells (birds)

And then, there’s the weird ones----  Insects and frogs undergo metamorphosis, where development is finished after hatching  Some snakes and sharks hold their eggs inside and give birth to live young  And the seahorses….!!!!

Development refers to-  The process from fertilized egg to living outside of egg or Mom  But, really, development happens for the organism’s entire lifetime

DIFFERENTIATION (that other “D word)  Happens soon after fertilization  Cells change in structure to prepare for different functions  Some genes “turn on” and others “turn off”  Organisms that can regenerate have cells that return to the embryonic state

The PURPOSE of reproduction  Is to create a new organism of the same species that will survive, whatever the strategy.

HUMAN Animals  Have INTERNAL FERTILZATION  Fully INTERNAL DEVELOPMENT, where the placenta and umbilical cord maintain the embryo inside the uterus

After Nine Months GESTATION  The placenta is no longer efficient enough to maintain the fetus, so it’s time for her or him to get out of there !

DEVELOPMENT  Continues for a long time in humans, most dramatically in the first years  Human children have an extended time of parental care  Aging happens from birth till death

HORMONES  Direct the changes that occur during development and growth  Begin maturing of egg and production of sperm at PUBERTY, usually in the early teens.

The Ability to Reproduce-  Wanes as humans age  Females cease menstruation at MENOPAUSE, after age 50  Males continue to produce sperm throughout lifetime

Next- Human Reproductive Systems 