6.4.1 natural clones

genetically identical organisms or cells

reproduction from vegetative parts of plant - usually over-wintering organ

= asexual reproduction • nucleus divided by mitosis • mitosis creates 2 identical copies of DNA • separated into 2 genetically identical nuclei • cell divides forming 2 genetically identical cells

• if growth conditions are good for parent, they will be good for offspring • cloning is relatively rapid so population can increase quickly • reproduction can be carried out even if 1 parent & sexual reproduction isn’t possible

• offspring may become overcrowded • no genetic diversity (other than potential mutation during DNA replication) • population shows little variation • selection isn’t possible • if environment becomes less advantageous, whole population is susceptible

• runners • stolons • rhizomes • suckers • bulbs • corms • leaves • tubers

• plants grow horizontal stems which can form roots at certain points • grow on surface of ground

• plants grow horizontal stems which can form roots at certain points • grow underground • some adapted as thickened over-wintering organs from which 1+ new stems will grow in spring

• new stems that grow from roots of plant • may be close to base of older stem or far away • original horizontal branch may die, leaving new stem as separate individual

(eg. onions) - over-wintering mechanism for many perennial monocotyledonous plants - consist of underground stem from which grows series of fleshy leaf bases - also an apical bud = grows into new plant in spring - often contains 1+ apical bud

• solid (not fleshy like a bulb) • underground stem with scaly leaves & buds • remain in ground during winter • in spring, buds grow producing 1+ plants (eg. taro)

• kalanchoe plant reproduces asexually, as clones grow on leaf margins • immature plants drop off leaf & take root

(eg. potatoes) - another type of underground stem - one potato will grow into 1+ plants - each new plant can produce many new tubers (potatoes) later that year

• identical twins - occurs when fertilised egg (zygote) divides as normal but 2 daughter cells split becoming 2 separate cells - each cell grows & develops into new individual • water flea & greenfly reproduce asexually producing clones