Finding the number of chromosomes of an organism

Question

For a school project I need to find the number of chromosomes of an organism (specifically the adelie penguin, Pygoscelis adeliae). After several internet searches and a look through the encyclopedia at school, I am unable to find a definite answer to this question. Sources on the internet claim anything from 38 to 96 for diploid cells (with none of them citing a trustable study).

Is there any database that records the chromosome number for organisms?

Also, if this information is unavailable, what is the best way to estimate this value? On the Wikipedia article for number of chromosomes for various organisms, it listed the value for some birds, most of them in the 70-80 range. Is it safe then to assume that the number for penguins in general would be somewhere in this range?

Thanks.

Answer 1

Answer

An comprehensive online database of the chromosome numbers of all living species most likely doesn't exist. This Wikipedia article is the best and most complete reference comprising animals that I can personally find on the internet.

This source in Spanish, which I've translated with Google Translate reads:

Canedo Delgado (1999) performed the karyotype description of the three species of the genus Pygoscelis , noting that there is a high homology both numerically and morphologically: Pygoscelis antarctica presented 2n = 92, Pygoscelis papua 2n = 94 and Pygoscelis adeliae 2n = 95 in females and 2n = 96 in males.

Also, note that chromosome number cannot be "guessed" or "assumed" for closely-related species. As shown above, the three Pygoscelis species have a high homology, but have very different chromosome numbers.

The other chromosome number you found for the species (38) is actually that of the Emperor penguin, as a simple Google search shows.

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References

• Ledesma, Mario A., T. R. O. Freitas, J. Da Silva, Fernanda Da Silva, and R. J. Gunski. “Descripción Cariotípica De Spheniscus Magellanicus (Spheniscidae).” El Hornero 18, no. 1 (August 2003): 61–64.

Answer 2

Since you didn't specify animals, I will add here for anyone coming from google that plant chromosome numbers are stored in the Index to Plant Chromosome Numbers.

I would be surprised if such a database exists for animals (except maybe insects) as historically C-numbers of plants and other cytogenetics were important for taxonomy (and still is important), whilst this was not the case so much in zoology.