1. Reproduction in animals- sexual vs asexual By Kristy Egan Group 4

2. What is reproduction? Reproduction is the creation of a new individual or individuals from previously existing individuals. In animals, this can occur in two primary ways: through asexual reproduction and through sexual reproduction.

3. Asexual reproduction In asexual reproduction, one individual produces offspring that are genetically identical to itself. These offspring are produced by mitosis. Mitosis is the phase of the cell cycle where chromosomes in the nucleus are evenly divided between two cells. When the cell division process is complete, two daughter cells with identical genetic material are produced.

4. Common forms of asexual reproduction include: Budding- In this form of asexual reproduction, an offspring grows out of the body of the parent. Gemmules (internal buds)- In this form of asexual reproduction, a parent releases a specialized mass of cells that can develop into offspring. Fragmentation- In this type of reproduction, the body of the parent breaks into distinct pieces, each of which can produce an offspring. Regeneration- In regeneration, if a piece of a parent is detached, it can grow and develop into a completely new individual. Parthenogenisis- This type of reproduction involves the development of an egg that has not been fertilized into an individual. Animals like most kinds of wasps, bees, and ants that have no sex chromosomes reproduce by this process. Some reptiles and fish are also capable of reproducing in this manner.

5. Asexual advantages and disadvantages Advantages- Animals that remain in one particular place and are unable to look for mates would need to reproduce asexually. Another advantage of asexual reproduction is that numerous offspring can be produced without "costing" the parent a great amount of energy or time. Environments that are stable and experience very little change are the best places for organisms that reproduce asexually Disadvantages- the lack of genetic variation. All of the organisms are genetically identical and therefore share the same weaknesses. If the stable environment changes, the consequences could be deadly to all of the individuals.

6. Asexual animals- Bees Bees use both sexual and asexual reproduction. The type of asexual reproduction that is used is parthenogenesis. When the queen bee lays eggs, some eggs will be fertilized and some will not be fertilized. The eggs that are not fertilized will turn into male worker, drone bees, which are sterile. The fertilized eggs will turn into female worker bees.

7. Sexual reproduction In sexual reproduction, two individuals produce offspring that have genetic characteristics from both parents. Sexual reproduction introduces new gene combinations in a population through genetic recombination. In animals, sexual reproduction encompasses the fusion of two distinct gametes (sex cells) to form a zygote. Gametes are produced by a type of cell division called meiosis. Meiosis is a two-part cell division process in organisms that sexually reproduce. Meiosis produces gametes with one half the number of chromosomes as the parent cell. In some respects, meiosis is very similar to the process of mitosis, yet it is also fundamentally different.

8. Common forms of sexual reproduction There are two mechanisms by which fertilization can take place. The first is external (the eggs are fertilized outside of the body); the second is internal (the eggs are fertilized within the female reproductive tract). Reproduction in animals is subject to certain patterns and cycles. Often these patterns and cycles may be linked to environmental conditions which allow organisms to reproduce effectively. These patterns can also be controlled by seasonal cues such as rainfall. This allows the animal to maximise their offspring’s chance of survival.

9. Sexual animals Sexual reproduction is the primary reproduction method for most animals including mammals, insects and fish. Some animals such as Polar bears have been known to mate with more than one male. DNA testing has proved a litter of cubs can have one father or different ones.

10. Diagram

11. References Images sourced from: http://www.bing.com/images/search?q=reproduction+in+animals&qpvt=reproduct ion+in+animals&FORM=IGRE http://biology.about.com/od/genetics/ss/Asexual-Reproduction.htm http://www.polarbear-world.com/polar-bear-reproduction/