How Do We get From

Animal Reproduction

ASEXUAL REPRODUCTION “the creation of new individual's whose genes all come from one parents without the fusion of egg and sperm.” -Campbell Biology Essentially Cloning the Parent

ASEXUAL REPRODUCTION Organisms are well adapted to stable environments cloning maintains the “best combination for the current situation” Less of a chance to introduce detrimental traits into the gene pool No need to find or compete for mates (saves time and energy and can reproduce in isolation) Can produce a large amount of offspring in a short amount of time

Asexual reproduction is best suited to stable environments in which individuals are already well adapted to survive This is because the “best traits” are identically copied into each successive generation ASEXUAL REPRODUCTION

Fission The splitting of a parent into two roughly equal sized offspring

Common among invertebrates Protozoan mag/art98/celldiv.html

Budding A new individual growing from and then splitting off from the parent The new offspring will either detach or remain attached to the parent. (This is common in tunicate, and cnidarians such as coral or hydra

udding_LP.jpg Hydra

Hydra

Gemmules Aggregates of several types of cells that are surrounded by a protective coating in sponges

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Fragmentation & Regeneration This occurs when an adult is broken into pieces and these pieces grow into new adult organisms. This is common among sponges, cnidarians, and tunicates.

SEXUAL REPRODUCTION “the creation of Offspring by the fusion of haploid gametes to form a zygote, which is diploid.” -Campbell Biology

SEXUAL REPRODUCTION Adds more variety to the population so as a whole the population is better situated to survive and prosper in rapidly changing or new environment Best in new or rapidly changing environment

Effects of sexual reproduction The Red Queen in “Alice in Wonder Land” had to run at full speed just to stay in the same place. This means that “a species must continually evolve to survive in a world full of other evolving species” –the science of ecology

One example are diseases. A cloned (or asexually reproduced) population is highly susceptible to being wiped out by a contagion. Predator prey relationships are another example

Sexes aren’t necessarily fixed or essential. Some species of frogs and tropical fish for example, change sexes depending on population dynamics (sometimes several times).

Types of Cells

Types of Cells Somatic  Any cell that is not a sex cell: egg (ovum) or sperm  Contain 46 chromosomes in humans

Types of Cells Sex Cells (gametes)  sex cells (egg or sperm)  Contain 23 chromosomes in humans 22 autosomal chromosomes & 1 sex chromosome

Y X

Sex Chromosome X & Y Females XX & Males XY

Autosome- all chromosomes that are not X or Y

Diploid All somatic cells are diploid meaning they have a full set of 46 chromosomes This is represented by the denotation 2n

Haploid All sex cells are haploid meaning they have a half set of 23 chromosomes This is represented by the denotation 1n

Fertilization Fertilization- is the fusion of the two gametes after sexual intercourse (sperm from the father and ovum from the mother) The resulting fertilized diploid egg is known as a zygote 23 chromosomes from the father and 23 from the mother

Plant Reproduction