Scientists discover a virgin birth (Parthenogen) in a crocodile

Context: Recently female crocodile in a Costa Rican zoo laid a clutch of eggs. That was peculiar: She’d been living alone for 16 years.

How does a virgin birth happen?

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  • As an egg cell matures in its mother’s body, it divides repeatedly to generate a final product with exactly half the genes needed for an individual.
  • Three smaller cellular sacs containing chromosomes, known as polar bodies, are formed as byproducts. Polar bodies usually wither away.
  • But in vertebrates that can perform parthenogenesis, one polar body sometimes fuses with the egg, creating a cell with the necessary complement of chromosomes to form an individual.
  • This process of Vergine birth (offspring containing only genetic material from its mother) is known as parthenogenesis

Parthenogenesis can be seen in the following creatures

  • King cobras
  • Sawfish
  • California condors
  • Crocodile
  • Some birds
  • Lizards

Why parthenogenesis occurs?

  • It’s possible that parthenogenesis gives a species the ability to survive extended periods when no mate is available.
  • A fresh individual, bearing largely the same genes as its parent, might live long enough for a mate to arrive, thus allowing sexual reproduction, which tends to produce hardier offspring.
  • But it is also possible that parthenogenesis is simply a trait that doesn’t have enough downsides for evolution to weed it out.
  • It is not necessarily a response to stress or even a lack of mates. In 2020, scientists discovered that lizards can mate and then lay clutches of eggs where some are normal offspring and some are parthenogens.
  • It’s an ability that can be switched on or off, and it is perhaps controlled by a single gene.

Practice MCQ

Consider the following organisms

1.      Sawfish

2.  California Condors

3.      Crocodile

4.  Lizards

How many of the above have the ability of Virgin birth (Parthenogen)

(A)   Only one

(B)   Only two

(C)   Only three

(D)   All four

Scroll down for answer










Ans. D

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