Reproductive strategies

Dispersal, variability, restsiant stages

Hermaphroditism in animals

Monoecious plants Having both unisexual - male and female flowers

Monoecious plants Having bisexual Flowers -- with both male and female parts

Apple has a perfect flower Green sepals (6) protect the bud before the flower opens. Petals (1) which people see as white, are highly visible to the insect pollinators. Male parts of the flower are called stamens, and consist of a filament (5) and anther (4). Pollen is produced in its anthers (4). When pollen grains mature, they land on the stigma (2), which is a receptacle for the style (a long tube that empties into the ovary (7)). The pollen grain then forms a pollen tube that grows down the style (3) and reaches the ovary (7),

Binary fission

Budding

Fragmentation

  Spore formation

Vegetative reproduction

Vegetative reproduction

Vegetative reproduction

Artificial Vegetative reproduction

Importance of Vegetative Propagation It is the only means of reproduction for seedless plants such as pineapples, seedless grapes, oranges, roses, sugarcane, potato, banana, etc. Plants raised through vegetative propagation are genetically similar. It preserves the type of characters that a plant breeder desires to retain. It is very economical and easy method for the multiplication of plants.

Artificial Vegetative reproduction To ensure a quick growth union, all cut surfaces are covered with a soft wax to prevent drying. The tissues of both the stock and the scion will fuse together and will make organic connection, getting nourishment from the stock, but producing fruits of scion retaining parental characters. Grafting is not possible is monocot plants since cambial activity is essential for the union of stocks and scion. Grafting blends the properties of two plants. It is also used in the production of dwarf fruit trees for the home gardens. High quality roses are usually grafted on wild rose root stocks. Other plants where grafting has been performed successfully are rubber, apple, pear, mango and guava.

Grafting peach into plum Main grafting steps: Trimming bark after cutting a branch to be grafted Next: Budwood inserted into branch Completed bark graft which has been tied with tape and waxed with grafting wax These peach grafts were been successful and have already produced blossoms This wild plum tree has now become half peach and half plum

Artificial Vegetative reproduction- tissue culture

Tissue culture

Application of tissue culture

Application of tissue culture Micro propagation of plants Plant tissue in very small amounts can produce hundreds or thousands of plants continuously. By using tissue culture methods, millions of plants with the same genetic characteristics can be obtained only from one eye buds. Improved crop In crop improvement efforts, pure strains can take six to seven generations of self-pollination or crosses. Through tissue culture techniques, homozygous plants can be obtained in a short time by producing haploid plants through pollen culture, anther or ovaries followed by chromosome doubling. Production of disease-free plants (virus) Tissue culture technology has contributed in a plant that is free from viruses. In plants that have been infected with the virus, the cells in the bud tip (meristem) is an area that is not infected with the virus. In this way virus-free plants can be obtained from the meristem. Genetic transformation For example, bacterial gene transfer (such as cry genes from Bacillus thuringiensis) into the plant cells ) The production of secondary metabolites, compounds Plant cell culture can also be used to produce biochemical compounds (secondary metabolites) such as alkaloids in industrial scale.

Inbreeding (Self-pollination) Advantages: Preserves well-adapted genotypes Insures seed set in the absence of pollinators Single colonizing individual possible Disadvantages: Decreases (or maintains) genetic variability

Outbreeding (Cross-pollination) Advantages: Increases genetic variability Strong evolutionary potential Adaptation to changing conditions Successful long-term Disadvantages: Can destroy well-adapted genotypes (offspring are not guaranteed to be viable) Relies on effective cross-pollination

Outbreeder or Inbreeder? Often one can tell just by looking at a flower whether it cross-pollinates or self-pollinates. OUTBREEDER INBREEDER self-incompatible self-compatible many flowers few flowers large flowers small flowers bright colors mono-colored nectaries present nectaries absent scented flowers unscented flowers nectar guides present nectar guides absent anthers far from stigma anthers close to stigma many pollen grains fewer pollen grains style exserted from flower style included in flower

Alternation of generation

Parthenogenesis Parthenogenesis a form of asexual reproduction found in females, where growth and development of embryos occurs without fertilization by a male.

Parthenogenesis in nature The Daphnia switch from sexual reproduction to asexual reproduction seasonally. When the environment is favorable, daphnia reproduce asexually. Under circumstances demonstrating environmental stress, the daphnia become sexually reproductive. Honey Bees tend to use parthenogenesis for the establishment of social organization. The male drones, or worker bees, reproduce solely through parthenogenesis. All females, both fertile queens and infertile workers, are created through sexual reproduction.