Genetics

mmfh

Arachnobaron
Joined
Jun 14, 2010
Messages
345
I was reading about genetic studies in tarantulas and to be honest it was all very confusing to me but one theme that ran through was the need for live or whole preserved specimens. i'm curious, why is it not possible to run a dna sequence using an exuvium? If scientists would do dna sequences on tarantulas wouldn't it clear up some of the confusion in the avicularia species.
 

jayefbe

Arachnoprince
Old Timer
Joined
Sep 20, 2009
Messages
1,351
Taxonomists today almost always use nuclear or mitochondrial sequences to inform their classifications. While it is helpful, it's still not perfect. Far from it. There is no sequence that says "this is species x". You still are left comparing sequences and trying to determine how similar something must be to be the same species, and how different it must be to be another.

To truly determine what comprises a different species, one must know their range, their mating habits, and if any pre or postzygotic reproductive isolation exists (gametic incompatibility, or hybrid sterility for example).
 

mmfh

Arachnobaron
Joined
Jun 14, 2010
Messages
345
I had no idea it was so complicated. Is this true of both mammals and arachnids? For example: dna would not be able to tell me if a bear was a polar bear or a black bear .... so I would need to know their range, mating habits, etc??
 

jayefbe

Arachnoprince
Old Timer
Joined
Sep 20, 2009
Messages
1,351
If you had samples of already known polar bears and black bears to compare it to, you could use DNA sequences to determine which species the sample came from. The problem with tarantulas is there is nothing to compare it to.

The issue with Avicularia (and many genera) is that the species hasn't been fully described yet. It is unknown if something collected from one location is the same species as something collected from another location. Are A. metallica green the same species as A. metallica? Without the field work and observing that they interbreed in the wild, there's no way of truly knowing. Also, many species were described a LONG time ago, back when taxonomy was much less sophisticated than it is now. It gets to the point, that sometimes things become so convoluted that what we might call species X today isn't the same as the holotype for that species. Without having something to compare it to, DNA sequences aren't going to offer a lot of insight.
 
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