Reason for cross-fertilization of hermaphroditic animals

[seasailor]

Is this just an issue of semantics or ???: From the text pg 72: "Note that most hermaphroditic animals utilize cross- rather than self-fertilization because the latter process reduces the possibility of genetic variation." The author(s) seems to imply a causality or intent on the part of the species when, it seems to me, that the process of evolution would eventually kill off the self-fertilization group due to a) genetic defects, b) lack of genetic adaptability (vs variability), or c) any other factor which makes the genetically-variable group more adaptable (e.g., succesful) in its environment.

Not determinism but evolution...

Cheers, Charles

 

[seasailor]

oh, rotifers....that's in the next chapter right?

Thanks, Charles

 

[rshimek]

Charles,

Well, your thoughts are somewhat close to the standard dogma, although keep in mind self-fertile animals may be very successful. Self-fertilization is effectively cloning, and this may be a good way to reproduce, although it certainly does limit the organisms options.

All Bdelloid rotifers are self-fertile - they are parthenogenic animals and no males have ever been found in the group. They don't seem do be "on the way out" - but they probably are not evolving either. These things may be real living fossils - unchanged for many millons of years.

Some animals - not many, actually- can be both self-fertile or out crossing. In these cases, self-fertilization is generally, the decided second choice. The animals use it only when it is apparent that no other mate will be available.

Most hermaphroditic organisms are obligate out-crossers.

 

[MKScom]

I'm confused.

If self-fertilizing organisms are seldomly out-crossing, and hermaphroditic organisms are usually out-crossing, then the two must be different.

I though hermaphrodites WERE self-fertilizing, but can't find both terms in the glossary.

Marty B

 

[rshimek]

Charles...

Rotifers are several weeks away.

Marty,

Hermaphroditic organisms are also known as monoecious animals. That term is the technical one and likely to be found in the glossary.

These animals may be simultanously hermaphroditic or sequentially. If they are the former, they may be capable of self-fertilization. Most of the time, they are not, however.