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Author Topic:   Winter Project
Tanypteryx
Member
Posts: 2571
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.5


(2)
Message 1 of 8 (885655)
04-21-2021 5:47 PM


At the moment I am taking a break from mowing my lawn, but on most days I am observing & photographing the development of embryos inside a clutch of 180 dragonfly eggs oviposited on Nov. 1, 2020. This is the 6th species within a group of closely related species I have worked with in this project that I started in 2017.

All eggs in the first 5 species were quite closely synchronized (within each species) in the timing of all developmental stages and hatching occurred in each group within just a couple days of each other. All the eggs were reared under the same conditions of temperature and photoperiod.

The species I am working with now is completely un-synchronized. The eggs all entered diapause (delayed development) after about 4 weeks, but then one egg recommenced development in January and hatched in early February. There was just a steady trickle of a couple a couple a day getting ready to hatch. There are still a few eggs that have not come out of diapause yet and at the same time I have nymphs that are in their 5th instar (molt). There may be between 10 and 17 instars depending on species and environmental conditions.

The species I have reared out so far can all share the same general habitat. I am trying to understand what kids of selective pressures would bake these developmental strategies into their genes.

When they hatch from their eggs they immediately shed their exoskeleton (the first molt) and become tiny little predators about 2mm long. They are partly transparent so I can see their internal structure and watch their respiratory contractions. Lots of things will eat them but they are fearless and routinely take on prey larger than themselves.

Until now, only a few species have had the development of eggs and nymphs documented, but an addition positive aspect of these projects is, for me, the development of very specialized photographic equipment and technique, to capture the details of this fascinating and complex process.

Cheers


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


Replies to this message:
 Message 2 by AZPaul3, posted 04-21-2021 6:26 PM Tanypteryx has responded

  
AZPaul3
Member
Posts: 5988
From: Phoenix
Joined: 11-06-2006
Member Rating: 3.6


Message 2 of 8 (885658)
04-21-2021 6:26 PM
Reply to: Message 1 by Tanypteryx
04-21-2021 5:47 PM


Yeah, so you say, but it didn't happen until you show us pictures.

Lots and lots of pretty pictures.


Eschew obfuscation. Habituate elucidation.

This message is a reply to:
 Message 1 by Tanypteryx, posted 04-21-2021 5:47 PM Tanypteryx has responded

Replies to this message:
 Message 3 by Tanypteryx, posted 04-21-2021 8:21 PM AZPaul3 has responded

  
Tanypteryx
Member
Posts: 2571
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.5


Message 3 of 8 (885661)
04-21-2021 8:21 PM
Reply to: Message 2 by AZPaul3
04-21-2021 6:26 PM


I sent you a PM.

What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


This message is a reply to:
 Message 2 by AZPaul3, posted 04-21-2021 6:26 PM AZPaul3 has responded

Replies to this message:
 Message 4 by AZPaul3, posted 04-21-2021 9:55 PM Tanypteryx has responded

  
AZPaul3
Member
Posts: 5988
From: Phoenix
Joined: 11-06-2006
Member Rating: 3.6


Message 4 of 8 (885662)
04-21-2021 9:55 PM
Reply to: Message 3 by Tanypteryx
04-21-2021 8:21 PM


I can appreciate your concerns. Too many crazies in this world.

I do have a q?

You said your first batch was synchronised while the second was not. Is the difference your selection process, luck of the draw or is there something else that accounts for the difference?


Eschew obfuscation. Habituate elucidation.

This message is a reply to:
 Message 3 by Tanypteryx, posted 04-21-2021 8:21 PM Tanypteryx has responded

Replies to this message:
 Message 5 by Tanypteryx, posted 04-21-2021 11:39 PM AZPaul3 has responded

  
Tanypteryx
Member
Posts: 2571
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.5


(1)
Message 5 of 8 (885664)
04-21-2021 11:39 PM
Reply to: Message 4 by AZPaul3
04-21-2021 9:55 PM


You said your first batch was synchronised while the second was not.

I'm sorry, I was unclear. There were 4 prior batches or species. Each species was unique and synchronized only with itself.

The 1st Species, Aeshna palmata oviposited more than 1200 eggs on 9-Oct-2017. The eggs were kept at a constant 68F with diffused daylight. They developed for 4-5 weeks and entered diapause. The 1st embryo resumed development 1-Jan-2018 and all the eggs had resumed within a week. The sign that development has restarted is each embryo actually switches ends inside the egg in a process called katatrepsis. The embyos continued development and began hatching in about 5 weeks and were all completed in 3 days.

The 2nd and 3rd species were both oviposited on 8-Aug-2018. The 2nd species was Rhionaeschna multicolor and it gave me 750 eggs that went through very rapid development and the eggs all hatched in 16 days.

The 3rd species, Aeshna interrupta developed for 4-5 weeks and seemed to be in diapause. Diapause ended in March and the nymphs all hatched within the same week in April.

In 2019 I was not able to get any of the Aeshna/Rhionaeschna females I collected to lay eggs for me. This family, the Aeshnidae, all oviposit endophytically, that is, into vegetation or other soft material like wet floating wood. I induce oviposition by placing a female in a gallon sized container with wet unbleached coffee filter papers on the bottom. stored in a dim cool place for a day or so and the coffee filters will be riddled with eggs, that I have to very carefully under a microscope extract the eggs from the paper without getting fiber stuck all over them. Tedious work, but I can also have sets of images or videos shooting and some classic rock or an audiobook and I an in the zone.

I did get eggs from a bunch of dragonflies that were kind enough to actually drop their eggs into a vial of water if you tap the tip of their abdomen on the water surface.

In May of 2020 I got about 500 eggs from a female Rhionaeschna californica that also went through rapid development and they all hatched on day 21 and 22.

And now I am watching the 5th species, Aeshna umbrosa, that is asynchronous in development.

My hypothesis is that each species has a unique embryo development genetic program. Each of these species has a flight season that is months long so there has to be some plasticity built in depending on when the eggs are laid. Development is accelerated or delayed depending on species, but triggered by photoperiod. In other orders of insects photoperiod and temperature are the determining stimuli.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


This message is a reply to:
 Message 4 by AZPaul3, posted 04-21-2021 9:55 PM AZPaul3 has responded

Replies to this message:
 Message 6 by AZPaul3, posted 04-22-2021 2:55 AM Tanypteryx has responded

  
AZPaul3
Member
Posts: 5988
From: Phoenix
Joined: 11-06-2006
Member Rating: 3.6


(1)
Message 6 of 8 (885667)
04-22-2021 2:55 AM
Reply to: Message 5 by Tanypteryx
04-21-2021 11:39 PM


So the asynchronous nature of Aeshna umbrosa is natural while the other four are all synchronous by nature. Are there major differences in environmental niche the 4 inhabit vis-a-vis Aeshna umbrosa? Seems it would have to be if the photoperiod is the determinant.

Unless ...

What is the timeline in the natural habitat for each species? Do they develop at different times during the season? Timed with predation?

What of the possibility that Aeshna umbrosa was late to the evolutionary party and this asynchronous timing was advantageous due to competition?

I'm just spouting.

I'm not a bug guy. I have no idea what I'm talking about. But this is interesting.

Edited by AZPaul3, : No reason given.


Eschew obfuscation. Habituate elucidation.

This message is a reply to:
 Message 5 by Tanypteryx, posted 04-21-2021 11:39 PM Tanypteryx has responded

Replies to this message:
 Message 7 by Tanypteryx, posted 04-22-2021 12:01 PM AZPaul3 has acknowledged this reply

  
Tanypteryx
Member
Posts: 2571
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.5


Message 7 of 8 (885678)
04-22-2021 12:01 PM
Reply to: Message 6 by AZPaul3
04-22-2021 2:55 AM


So the asynchronous nature of Aeshna umbrosa is natural while the other four are all synchronous by nature. Are there major differences in environmental niche the 4 inhabit vis-a-vis Aeshna umbrosa? Seems it would have to be if the photoperiod is the determinant.
Unless ...

The microhabitat of A. umbrosa nymphs seems to be pretty much the same, and I have never seen an analysis that compares the microhabitats. Beyond 4th instar all dragonfly nymphs will prey on other nymphs if they come in range of their prehensile labium (lower lip).

The flight seasons of adults of all these species are different but some of them overlap quite a bit. They are all large strong flying insects that are habitat generalists rather than specialists. The nymphs of these species are all prey stalkers rather than lying in wait and ambushing their prey. They hunt primarily by vision but are also very sensitive to vibrations.

What of the possibility that Aeshna umbrosa was late to the evolutionary party and this asynchronous timing was advantageous due to competition?

Avoiding competition with conspecifics could certainly be a factor and with other species to a lesser extent.

Edited by Tanypteryx, : No reason given.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


This message is a reply to:
 Message 6 by AZPaul3, posted 04-22-2021 2:55 AM AZPaul3 has acknowledged this reply

Replies to this message:
 Message 8 by Tanypteryx, posted 05-07-2021 5:52 PM Tanypteryx has not yet responded

  
Tanypteryx
Member
Posts: 2571
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 5.5


(2)
Message 8 of 8 (886146)
05-07-2021 5:52 PM
Reply to: Message 7 by Tanypteryx
04-22-2021 12:01 PM


Dragonfly Musings
The oldest A. umbrosa nymph is now in instar 6 and there are still 3 eggs out of 180 that are in diapause and about a dozen that have completed katatrepsis and will hatch within the next 2 weeks. The asynchronous development pattern of these eggs has continued. All the eggs developed normally and entered diapause and then a couple months later 1-4 eggs per day would end diapause by going through katatrepsis, continue developing for 2 weeks and then hatch.

Every other species I have reared were quite synchronized in embryo development and hatching and that would plot against time in a steep, narrow bell curve, this includes closely related species in the same genus.

In the early 80's I reared 2 species that each took 5 years to develop from egg to adult, Cordulegaster dorsalis and Tanypteryx hageni. After 5 years I had a dozen or so surviving C. dorsalis nymphs. Several weeks before they are ready to emerge the nymphs would crawl out of the water onto twigs to explore. I placed a dry woody shrub branch in their habitat to crawl out on and got my camera all set up ready to record metamorphosis into adults. All week end I waited.... Monday morning I had to go to work at 4:00 AM, at 5:00 my wife called and said, "they are hatching!" I told her to shoot them and she got a wonderful series of shots that show all the stages of metamorphosis.

So, after 5 years they all emerged within minutes of each other. The Tanypteryx eggs were spread over 3 days but that's still incredibly tight.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


This message is a reply to:
 Message 7 by Tanypteryx, posted 04-22-2021 12:01 PM Tanypteryx has not yet responded

  
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