What is the Difference Between Self and Cross Fertilization?

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The main difference between self and cross fertilization lies in the pollination process and the individuals involved. Here are the key differences:

  • Self-fertilization: This occurs when the pollen is transferred through the stigma of the same flower of the same plant. It involves only one individual, and the male and female gametes (sex cells) come from the same organism. Self-fertilization is more common in hermaphroditic species, where the same individual produces both sperm and eggs.
  • Cross-fertilization: This occurs when the pollen is transferred through the stigma of another flower, usually of a different plant. Cross-fertilization involves the fusion of male and female gametes produced by different individuals of the same species. This process is essential for dioecious plants (those having male and female organs on separate individuals) and in all animal species in which there are separate sexes.

Advantages and disadvantages of self and cross fertilization:

Self-fertilization can help maintain local populations and desirable genetic traits, but it reduces genetic variation among offspring. In contrast, cross-fertilization increases the adaptability of organisms to survive in changing environments by allowing for greater genetic diversity. Cross-fertilization can also result in hybrid vigor, producing healthier and stronger offspring.

Comparative Table: Self vs Cross Fertilization

The main difference between self-fertilization and cross-fertilization lies in the genetic diversity they produce in their offspring. Self-fertilization involves the fusion of male and female gametes produced by the same individual, while cross-fertilization involves the fusion of male and female gametes from different individuals of the same species. Here is a table comparing the differences between self and cross fertilization:

Feature Self-Fertilization Cross-Fertilization
Genetic Diversity Reduced Increased
Gene Pool Reduced Maintained
Offspring Genetically similar Genetically diverse
Inbreeding Causes Prevents
Pollen production Limited Large amounts
Pollen transfer Few pollen grains Large numbers of pollen
Time of anther and stigma maturation Simultaneous maturation Staggered maturation

Self-fertilization occurs in flowers that are genetically identical and can be seen in species like orchids, sunflowers, peas, peanuts, oats, peaches, potatoes, and wheat. Cross-fertilization, on the other hand, occurs between flowers with different genetics and is observed in species like apples, daffodils, pumpkins, and grasses. Cross-fertilization helps maintain a greater range of variability for natural selection to act upon, thereby increasing a species' capacity to adapt to environmental change.