At times, unfavorable environmental conditions can cause one gender of a certain population of organisms to drastically decline. During such times, the other gender makes up for the decline by reproducing on its own. This type of reproduction is called . The first vertebrate organism to have successfully produced offspring in this manner is the

Parthenogenesis, Poecilia formosa

Explanation:

Parthenogenesis can be defined as a natural type of asexual reproduction in which the production and development of the embryos takes place without the fertilization of sperms. This helps the female partner to reproduce offsprings individually. The first vertebrate in which the parthenogenesis was observed was a fish species called  Poecilia formosa in 1932. The female fish undergo asexual reproduction to produce offsprings.

b) mutualism

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1.solid

2.carbon dioxide

3.helium