A Plant With More Chromosomes Than You
You might be surprised to learn that some species of ferns have over 1200 chromosomes. That?s over 26 times more chromosomes than humans? measly 46! In fact, the world record holder for the most chromosomes is the fern Ophioglossum reticulatum with 1260 chromosomes!
Amazing But True!
- Humans and most other animals are diploid, meaning that they have two sets of chromosomes.
- Through the course of evolution, some species have generated multiple copies of their chromosomes due to errors in meiosis, when the sex cells or gametes are produced. Gametes normally have half the number of chromosomes as other cells in the body, but errors can occur when the chromosomes don?t separate properly, creating multiple copies. Having more than two copies of each chromosome is called polyploidy.
- Polyploidy is common in plants, with the fern taking it to the extreme with its thousands of chromosomes. It also occurs in some species of insects, fish, amphibians, crustaceans, and reptiles.
- Watch this video to learn more about why ferns and some other organisms have so many chromosomes:
Show What You Know
Read the links below to learn more about polyploidy in ferns and other organisms. Then answer the following questions.
- What organism has the smallest number of chromosomes?
- Why does Dr. Paul Wolf think that ferns might have so many chromosomes compared to other organisms?
- What usually happens in mammals, including humans, when errors occur that result in polyploidy?
- What percentage of flowering plants are polyploid?
- Why does Jennifer Frazier speculate that plants may be more tolerant of polyploidy than mammals?