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An overriding
evolutionary process in tropical forests?
Q3. DEFINE inbreeding and outcrossing as they relate to plant reproductive biology. Q4. LIST the possible advantages/disadvantages of each of the above processes I have combined the answers to these two questions. The processes of inbreeding and outcrossing refer to the predominant sexual reproductive mechanisms operating in a plant species. Both may occur in a facultative manner. Inbreeding assumes fertilisation occurring as a result of pollination from flowers on the same plant or in the same flower. Thus the genetic constitution of the pollen and egg cell will be the same and little genetic variability will be exhibited in the offspring. Inbreeding can very generally be said to produce clones of the parent, and may be seen as being advantageous in environments where large numbers of individuals can be produced which will survive in current conditions. Limitations are obviously associated with lack of genetic variability in that individuals may not survive if conditions change. Outcrossing involves pollen from flowers with a different genetic constitution fertilising an egg. Offspring are genetically different from each other and the parent, and may therefore be able to survive in varying conditions or colonise new areas. Plants have many self incompatibility mechanisms to ensure outcrossing, even in monoecious individuals or hermaphrodite flowers. Once you have an understanding of these processes and the implications of their differences you should move on to look at details of field and lab research projects. |