parthenogenesis: female reproduction without male

What is parthenogenesis?

This word can be split into two part.

The prefix partheno- is from Greek word parthenos, meaning virgin; and the suffix -genesis means production. Put them together, parthenogenesis means sexual reproduction with development of a gamete without fertilization.

Parthenogenesis can be found in some plants and invertebrates, especially arthropods. For vertebrates it was only observed under captivity.

However, in a study done by Stony Brook University, they found that about 3% of the smalltooth sawfish (Pristis pectinata) underwent parthenogenesis.

Smalltooth sawfish. Source: Science Daily

Smalltooth sawfish is one of the large fish living in Florida. It was listed as endangered in 2003 because the population decreased to 1-5% (about 200 individuals left) of 1900.

Concerning about inbreeding, the scientists started to do their DNA fingerprinting. Surprisingly, they found some of the females were reproducing without mating.

There were five of them that are extremely close to each other, according to the DNA fingerprinting result.

In the past, parthenogenesis only happened for sharks in captivity, not to mention those sharks weren't healthy at all.

Perhaps it is a way to preserve the population when the population size is so low. Although parthenogenesis does not help with genetic diversity, it will help to maintain the population size.

Reference:

Andrew T. Fields, Kevin A. Feldheim, Gregg R. Poulakis, Demian D. Chapman. 2015. Facultative parthenogenesis in a critically endangered wild vertebrate. Curr. Biol. 25（11）：R446-R447

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