Steve
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The Importance of Sex

Sex is important to life on Earth. It is not just Humans and the higher animals that need sex. Whether species were created or evolved, or both or neither, there are not many that have no form of sexual reproduction. Of course, many species also can reproduce without sex, but the fact that they can reproduce sexually is of great evolutionary significance. If a species loses its ability to sexually reproduce, its ability to adapt is much less.

Humans usually reproduce sexually. The great majority of Humans are the result of purely sexual reproduction. Although on fairly rare occasions Humans do reproduce asexually by binary fission, splitting into two separate individuals this only accounts for a small percentage of the Human population of the world.


It is also worth noting that quite often, even when asexual reproduction occurs; it frequently follows on from sexual reproduction.

From the evolutionary point of view, sexual reproduction is very necessary.  Even relatively simple creatures like bacteria can exchange genetic material and can adapt very quickly.


Imagine life on a planet that had no means of sexual reproduction. I would suggest that they would not have the ability to evolve in the same way as life on Earth can.

Of course my suggestion that sexual reproduction is necessary implies that species that have lost this ability and rely on asexual reproduction only are at risk of being at an evolutionary dead end. For example, a plant called the sour sob, Oxalis pes-capri, was formed by a Chromosome mutation resulting in it being pentaploid. At first this was believed to be an evolutionary dead end that was unable to adapt further. Now a population of this highly successful plant has been discovered that sets seed, so it is now reproducing sexually.

Another plant, Duckweed (Genus Lemna) normally reproduces only asexually by budding into two genetically identical individuals. However, on rare occasions this plant will flower and can change by recombination of genes. In the evolutionary sense this is of great importance to the plant.
 
 
 
 
 
 
















 





 




 



 


 

 
  
Oxalis pes-caprae.  The pentaploid form of this plant normally does not reproduce sexually although a sexually reproducing population was found.              

 
A Nine Banded Armadillo.  This type of Armadillo typically has four babies at a time.  These are identical quadruplets produced by the asexual devision of a single fertilized egg which was produced sexually in the usual mamalian manner.
By Jerry Segraves (en:User:Jsegraves99) [Attribution], via Wikimedia Commons