Why are two gametes needed for reproduction?

I've always wondered why are two gametes needed for a new offspring to be born? The existence of two gametes let to the creation of two sexes, but i want somebody to explain to me why are two gametes needed in the first place? Why can't new offspring be born from a single organism? 

Update:

WHY are TWO individuals needed? That is literally my entire question. Why can't it be just ONE? 

9 Answers

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  • Paul
    Lv 7
    3 weeks ago

    They are forms of asexual reproduction in some primitive invertebrate species.  But sexual reproduction by definition requires union of a male and female gamete.

  • 3 weeks ago

    That is a good question. The earliest form of reproduction was binary fission, meaning splitting in half to make two where there was once one. Some mechanism was needed to make sure that each new half would have a complete copy of the creature's genes. But such a system is not conducive to promoting genetic variation. Then multicellular organisms developed a strategy where reproduction was accomplished by sending out a bunch of offspring cells with only 1/2 of the necessary genes, requiring that these resulting "haploid" cells would have to find and merge with another haploid cell in order to have a complete copy of the necessary genes, leading to an offspring with a totally new genetic shuffling, which would then be derived from two parents, rather than just one. A large number of these haploid cells would be put forth into the environment, and once merged with haploid cells from other creatures, there would be a highly variegated population of new offspring due to the randomness of the reshuffling of the genes. 

    Then natural selection "survival of the fittest" would kill off the less successful combinations, leading to greater survival competence of the survivors. When this process is repeated over and over, generation after generation, the species that could reproduce in this genetic reshuffling manner would out-evolve any species that reproduced by simple fission. Thus sexual reproduction was able to vastly outpace all previous methods of reproduction. 

  • 4 weeks ago

    Some organisms reproduce asexually. Bacteria, for example. It's also been observed in lizards and snakes. In fact, the majority of organisms reproduce asexually, as all the species of bacteria combined outnumber the amount of other groups of organisms by a significant margin. 

    Why do most animals and most plants need two? It promotes genetic diversity.

  • 4 weeks ago

    Sexual reproduction is a process that creates a new organism by combining the genetic material of two organisms. One of the most widely accepted explanations for the advantage of sex lies in the creation of genetic variation, which provides a

    significant increase in the fitness of the offspring.

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  • 4 weeks ago

    There are plenty of "just one" species.

  • Anonymous
    4 weeks ago

    Sexual reproduction evolved so 2 different individuals can combine their genes. Before sex, organisms reproduce by cloning themselves. Their offspring will  have all their genes but not other potentially good ones that may have evolved in other individuals. Sexual reproduction however can result in double the genetic material each time, after a few generations, the amount of genetic material can increase exponentially, so that the entire cell would be stuffed with nothing but DNA. Obviously that cannot work because there are lots of things a cell must do to survive. Therefore it was necessary to have gametes that half only half of the amount of DNA so that when 2 gametes meet, the offspring will have the same amount of DNA as the parents. 

    2 gametes do not always have to meet. Some organisms can reproduce by parthenogenesis. The haploid egg of the female can start dividing without being fertilized, but the offspring are all female. Snakes, lizards and other animals can reproduce this way. In ants and bees, the unfertilized egg can develop into males without being fertilized, so it is possible that only one gamete alone can become an adult. 

  • Anonymous
    4 weeks ago

    In sexual reproduction, two individuals produce offspring that inherit genetic characteristics from both parents. Sexual reproduction introduces new gene combinations in a population through genetic recombination. The influx of new gene combinations allows members of a species to survive adverse or deadly environmental changes and conditions. This is a major advantage that sexually reproducing organisms have over those that reproduce asexually. Sexual reproduction is also advantageous as it is a way to remove harmful gene mutations from a population through recombination. 

  • Dixon
    Lv 7
    4 weeks ago

    As far as I know, the origin of having two sexes is not fully understood and there is no consensus on what advantages it conferes. There are lifeforms with assexual reproducion and self reproduction.

  • Jim
    Lv 7
    4 weeks ago

    Greater diversity of genes allows greater survivability from any given disease.

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