Polyploid (in CC amphib glossary)

[John]

Polyploidy/Polyploid is a term used to describe the state of having more than the "normal" 2 sets of chromosomes in a cell nucleus (a cell or animal with two sets is known as diploid). There are many states of polyploidy and they are named according to the Greek numerical prefix for the number of sets of chromosomes present: triploid describes a cell or animal with three sets; tetraploid describes a cell or animal with four sets; pentaploid is five sets, hexaploid is six sets, heptaploid is seven and so on.

See also Haploidy.

 

[Jennewt]

Could we have an example or two relating to caudates? There are some that are triploid or tetraploid but I don't have the details in-hand.

 

[Jan]

Any thoughts on examples?

 

[Daniel]

There are some examples given in Duellman & Trueb (table 16.4):

- Ambystoma platineum: 14 x 3
- Ambystoma tremblayi: 14 x 3
- A. texanum x laterale: 14 x 3
- Pseudobranchus striatus: 16 x 4
- Siren lacertina: 13 x 4

 

[Jan]

Ah, good stuff Daniel. Ambystoma platineum and Ambystoma tremblayi are no longer considered valid species however. I believe they are considered Ambystoma laterale but are part of the unisexual ambystoma complexes.

How about this as a final definition with example:

Polyploid: A term used to describe the state of having more than the "normal" 2 sets of chromosomes in a cell nucleus (a cell or animal with two sets is known as diploid). There are many states of polyploidy and they are named according to the Greek numerical prefix for the number of sets of chromosomes present: triploid describes a cell or animal with three sets; tetraploid describes a cell or animal with four sets; pentaploid is five sets; hexaploid is six sets; heptaploid is seven and so on. An example would be salamanders from the [Unisexual] Ambystoma Complexes which can be diploid, triploid, tetraploid or pentaploid. These polyploid female salamanders are considered to reproduce by [kleptogenesis]. See also [haploid].

 

[Daniel]

Will there be a definition of "diploid"?

If not - I would add that in normal cases with diploid animals one set of chromosomes comes from the paternal side and the other part from the maternal side (you might want to rephrase that to the correct terms).

 

[Jan]

Daniel - good thought and I've created a new thread for diploid - see what you think of the def.