Troutnut.com Fly Fishing for Trout Home
User Password
or register.
Scientific name search:

> > Mayflies: subimago to imago .... ?, Page 2



KonchuApril 29th, 2007, 8:09 pm
Site Editor
Indiana

Posts: 505
What might eliminate the spinner state? Hmmmm...

Perhaps some efficient predator eats the winged stages. Those individuals that released eggs the soonest would be selected "for." This is because those that tend to deposit eggs later in life never make it that far and are selected "against." Those that live reproduce and pass on their genes.
QuillgordonApril 30th, 2007, 5:10 am
Schuylkill County, PA.

Posts: 109

Perhaps some efficient predator eats the winged stages. Those individuals that released eggs the soonest would be selected "for." This is because those that tend to deposit eggs later in life never make it that far and are selected "against." Those that live reproduce and pass on their genes.


At the present(correct me if I'm wrong), the sexual organs are not fully developed until the last molt or spinner stage. So the above senerio would still occur in the imago state not the subimago state.
What I meant was ...... could there be 'selection processes' that cause the subimago to emerge as a fully developed adult that could mate ( in a short amount of time), so it would not have to further molt into what we see as a spinner?
I guess I'm trying to make an analogy to caddis flies! They emerge as fully developed adults capable of mating.

Flyfishing is a state of mind! .............. Q.g.

C/R........barbless
TroutnutApril 30th, 2007, 6:46 am
Administrator
Bellevue, WA

Posts: 2737
At the present(correct me if I'm wrong), the sexual organs are not fully developed until the last molt or spinner stage.


I'm not sure if that's true. The organs certainly aren't in their final form in the dun stage, but maybe they're fully developed and just compressed within the dun's packaging until the molt. I know that's the case with the long fore legs of male spinners, but I don't know about the reproductive organs. Maybe one of the real entomologists can answer that one.

In other words, I'm not sure if there's actual growth/development during the dun stage, or if everything is grown in the nymph and just waiting to be used.

The reproductive organs aren't the only reason for mayflies to turn into spinners before trying to mate, though. Spinners have several other useful adaptations, like the longer legs on the males, which are handy for grasping the females mid-flight. Spinners are also much better at flying than duns, which makes them harder to catch, which is good because they spend so much more time in the air than duns. It's also useful because they have to maneuver to link up with mates. I wouldn't be surprised if their eyesight is better, too.

What I meant was ...... could there be 'selection processes' that cause the subimago to emerge as a fully developed adult that could mate ( in a short amount of time), so it would not have to further molt into what we see as a spinner?


Yes, there could! Females in the Ephoron genus ("White Flies") mate and die as duns.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
QuillgordonApril 30th, 2007, 2:00 pm
Schuylkill County, PA.

Posts: 109
Jason,
When I said the males are not fully developed , I was basing it on this:
Although all female mayflies are evidently sexually mature
as subimagos and male subimagos possess mature gametes, males evidently
are never reproductively mature as subimagos, i.e. male subimagos cannot
mate. We have never found fully formed male genitalia, including the femaleclasping
forceps, in subimagos of any species. The male genitalia grow in a
paurometabolous fashion rather than being prepackaged like legs and wings,
and this may be a major factor in restricting mating to male adults.
The fact that adult properties have not been incorporated into the male
subimago so that the final molt might be eliminated may be due to some
incompatability of the hydrofuge function with possible emergence function
and the mate-capturing and copulating function. If such incompatibility exists
we cannot account for it, particularly in view of some other aquatic insects
that combine the roles in the ultimate instar. We must continue to assume that
two molts from the larval stage are required for males to attain reproductive
maturity and function. Thus the subimago has at least some necessary role in
transformation.


I like the fact that mayflies are unique. I don't think we will see any further change in our lifetime!
John....
Flyfishing is a state of mind! .............. Q.g.

C/R........barbless
TroutnutMay 2nd, 2007, 2:45 pm
Administrator
Bellevue, WA

Posts: 2737
Good work! You've got the answer, then. I knew about the legs and wings being prepackaged, but didn't realize the important parts are still growing in the dun.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
QuillgordonMay 2nd, 2007, 4:33 pm
Schuylkill County, PA.

Posts: 109
Jason,
Maybe this would be a good subject for a paper by someone getting a degree in 'Entomology'.

Cheers.....
Flyfishing is a state of mind! .............. Q.g.

C/R........barbless
Page:12

Quick Reply

You have to be logged in to post on the forum. It's this easy:
Username:          Email:

Password:    Confirm Password:

I am at least 13 years old and agree to the rules.

Related Discussions

TitleRepliesLast Reply
Re: deligon
In the Stonefly Family Nemouridae by Deligon
2Jan 22, 2010
by Martinlf
Re: Differences I'm dying to know about
In the Mayfly Genus Tricorythodes by Reify
2Jul 9, 2018
by Martinlf
Re: shuck and belly
In Male Baetis Mayfly Dun by Martinlf
2Dec 27, 2006
by Martinlf
Re: lateseason mayfly
In the Identify This! Board by Lifeaquatic
2Dec 11, 2007
by Lifeaquatic
Re: White Mayfly ---- Euphron leukon?
In the Identify This! Board by JumpNotZero
1Sep 9, 2008
by GONZO
Re: Spinner Mayfly
In General Discussion by Jesse
2May 13, 2012
by Konchu
Re: Blue Quill Confusion
In General Discussion by Lastchance
16Aug 5, 2010
by Gutcutter
Re: Mayfly I.D.
In the Identify This! Board by MarkP
4Aug 26, 2008
by Taxon
Re: Nectopsyche larva and pupa
In the Identify This! Board by Millcreek
7Jun 19, 2015
by Oldredbarn
Re: Help with ID
In the Identify This! Board by Calloway
2Jul 9, 2008
by Wiflyfisher