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[Leps-l] monarchs, reversal of orientation and overwintering temperatures
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Chip Taylor
Feb 21, 2013, 1:46:17 PM2/21/13
to
http://www.climatecentral.org/news/spring-chill-sends-monarchs-fluttering-north-15634
http://www.cell.com/current-biology/abstract/S0960-9822(13)00087-0
Coldness Triggers Northward Flight in Remigrant Monarch Butterflies
Current Biology, 21 February 2013
Copyright � 2013 Elsevier Ltd All rights reserved.
10.1016/j.cub.2013.01.052
Authors
Patrick A. Guerra
,
Steven M. Reppert
Summary
Each fall, eastern North American monarch
butterflies (Danaus plexippus) migrate from their
northern range to their overwintering grounds in
central Mexico [1,2,3]. Fall migrants are in
reproductive diapause, and they use a
time-compensated sun compass to navigate during
the long journey south [4,5,6]. Eye-sensed
directional cues from the daylight sky (e.g., the
horizontal or azimuthal position of the sun) are
integrated in the sun compass in the midbrain
central complex region [7,8]. Sun compass output
is time compensated by circadian clocks in the
antennae so that fall migrants can maintain a
fixed flight direction south [9,10]. In the
spring, the same migrants remigrate northward to
the southern United States to initiate the
northern leg of the migration cycle. Here we show
that spring remigrants also use an
antenna-dependent time-compensated sun compass to
direct their northward flight. Remarkably, fall
migrants prematurely exposed to
overwintering-like coldness reverse their flight
orientation to the north. The temperature
microenvironment at the overwintering site is
essential for successful completion of the
migration cycle, because without cold exposure,
aged migrants continue to orient south. Our
discovery that coldness triggers the northward
flight direction in spring remigrants solves one
of the long-standing mysteries of the monarch
migration.
_______________________________________________
Leps-l mailing list
Lep...@mailman.yale.edu
http://mailman.yale.edu/mailman/listinfo/leps-l
http://www.cell.com/current-biology/abstract/S0960-9822(13)00087-0
Coldness Triggers Northward Flight in Remigrant Monarch Butterflies
Current Biology, 21 February 2013
Copyright � 2013 Elsevier Ltd All rights reserved.
10.1016/j.cub.2013.01.052
Authors
Patrick A. Guerra
,
Steven M. Reppert
Summary
Each fall, eastern North American monarch
butterflies (Danaus plexippus) migrate from their
northern range to their overwintering grounds in
central Mexico [1,2,3]. Fall migrants are in
reproductive diapause, and they use a
time-compensated sun compass to navigate during
the long journey south [4,5,6]. Eye-sensed
directional cues from the daylight sky (e.g., the
horizontal or azimuthal position of the sun) are
integrated in the sun compass in the midbrain
central complex region [7,8]. Sun compass output
is time compensated by circadian clocks in the
antennae so that fall migrants can maintain a
fixed flight direction south [9,10]. In the
spring, the same migrants remigrate northward to
the southern United States to initiate the
northern leg of the migration cycle. Here we show
that spring remigrants also use an
antenna-dependent time-compensated sun compass to
direct their northward flight. Remarkably, fall
migrants prematurely exposed to
overwintering-like coldness reverse their flight
orientation to the north. The temperature
microenvironment at the overwintering site is
essential for successful completion of the
migration cycle, because without cold exposure,
aged migrants continue to orient south. Our
discovery that coldness triggers the northward
flight direction in spring remigrants solves one
of the long-standing mysteries of the monarch
migration.
_______________________________________________
Leps-l mailing list
Lep...@mailman.yale.edu
http://mailman.yale.edu/mailman/listinfo/leps-l
MexicoDoug
Feb 21, 2013, 5:30:52 PM2/21/13
to
Chip,
Thanks for the links, it is part of an interesting study if you aren't
squeamish about amputating Monarch antennae and watching carefully what
happens! If I can get a free copy of this complete paper it will be
interesting to read ... In the mean time, a free pdf is available here:
http://reppertlab.org/media/files/publications/natcomm2012.pdf
which seems to cover the same experiment except notably for the module
of suspending some of the Monarchs in Texas, in an artificial fall
condition during the migratory and overwintering period to fool the
Monarchs into thinking they are still in Autumn ... effectively by
swapping the Northern and Southern equinoxes' to give the Monarchs a
form of Jet Lag that is undetectable by some senses.
The release point basically is at the same temperature after the
seasonal swap, correct? The artificial autumn condition created seems
to be an average of around 61 degrees F, with limits of something like
54 degrees F > temp > 68 F.
This seems then to be contrasted with a current estimate 36 degree F
low (January) temperature in the Mexico State & Michoacan State
overwintering region and another attempt to show that prolonged cooling
of undetermined length to Monarchs already in diapause is a dependable
way to orient the Monarchs northward even in short winters.
The provocative conclusion seems to be if the Monarchs can be given
seasonal jet lag under the right conditions and not notice while they
were in the lab --- that they gained a half season. The suggestion
that without experiencing the cold temperatures in their Oyamel woods
that the Monarchs can be fooled. It is interesting in the sense that
it argues that this effectively says the Monarchs' "compass" is really
only a 180 degree compass and I would infer is requiring diapause and
all the biochemical/physiological reactions that accompany it to
calibrate with hemisphere of the compass is "up".
As an amateur and conservationist, think it is a very constructive
work, but a few more Monarchs need to be seasonally jet-lagged
(sans-antennae amputees) to figure out the relationship between
entering diapause, flip/flopping navigational 'compasses', and if it
all plays out according to the hypothesis, precising for how long and
at what temperature (not studied between 36 and 61 degrees F) in a
predictive sense these Monarchs need to be exposed to go into diapause.
Unless of course, the study is saying that diapause is unrelated to
the proposed N/S calibration/inversion observed in these laboratory
Monarchs. Right?
That's what I get from this, where the interesting diligence here,
besides utilizing this "disappearance bearing" (As a layman this gives
me discomfort since measurement of disoriented butterflies after
initial release is being generalized, and not all individuals' bearings
are being counted which has the potential to introduce experimental
bias - though I have no idea how it could be done better without GPS
trackers or huge experiments with tags via something like Monarch
Watch) is a laboratory attempt to control photo-period length; and the
implication to conservation of the migration would seem to me not
addressed since even under the most pessimistic scenarios, no one is
saying that it will be 61 degrees at those elevations in the Monarchs'
dominion of Oyamel woods. But it does build on studies during a time
much less had been determined about the 'compass', at that time which
suspected but did not confirm this at least as far back as Herman, WS
(1981)
http://www.biolbull.org/content/160/1/89.full.pdf
Best wishes
Doug
Thanks for the links, it is part of an interesting study if you aren't
squeamish about amputating Monarch antennae and watching carefully what
happens! If I can get a free copy of this complete paper it will be
interesting to read ... In the mean time, a free pdf is available here:
http://reppertlab.org/media/files/publications/natcomm2012.pdf
which seems to cover the same experiment except notably for the module
of suspending some of the Monarchs in Texas, in an artificial fall
condition during the migratory and overwintering period to fool the
Monarchs into thinking they are still in Autumn ... effectively by
swapping the Northern and Southern equinoxes' to give the Monarchs a
form of Jet Lag that is undetectable by some senses.
The release point basically is at the same temperature after the
seasonal swap, correct? The artificial autumn condition created seems
to be an average of around 61 degrees F, with limits of something like
54 degrees F > temp > 68 F.
This seems then to be contrasted with a current estimate 36 degree F
low (January) temperature in the Mexico State & Michoacan State
overwintering region and another attempt to show that prolonged cooling
of undetermined length to Monarchs already in diapause is a dependable
way to orient the Monarchs northward even in short winters.
The provocative conclusion seems to be if the Monarchs can be given
seasonal jet lag under the right conditions and not notice while they
were in the lab --- that they gained a half season. The suggestion
that without experiencing the cold temperatures in their Oyamel woods
that the Monarchs can be fooled. It is interesting in the sense that
it argues that this effectively says the Monarchs' "compass" is really
only a 180 degree compass and I would infer is requiring diapause and
all the biochemical/physiological reactions that accompany it to
calibrate with hemisphere of the compass is "up".
As an amateur and conservationist, think it is a very constructive
work, but a few more Monarchs need to be seasonally jet-lagged
(sans-antennae amputees) to figure out the relationship between
entering diapause, flip/flopping navigational 'compasses', and if it
all plays out according to the hypothesis, precising for how long and
at what temperature (not studied between 36 and 61 degrees F) in a
predictive sense these Monarchs need to be exposed to go into diapause.
Unless of course, the study is saying that diapause is unrelated to
the proposed N/S calibration/inversion observed in these laboratory
Monarchs. Right?
That's what I get from this, where the interesting diligence here,
besides utilizing this "disappearance bearing" (As a layman this gives
me discomfort since measurement of disoriented butterflies after
initial release is being generalized, and not all individuals' bearings
are being counted which has the potential to introduce experimental
bias - though I have no idea how it could be done better without GPS
trackers or huge experiments with tags via something like Monarch
Watch) is a laboratory attempt to control photo-period length; and the
implication to conservation of the migration would seem to me not
addressed since even under the most pessimistic scenarios, no one is
saying that it will be 61 degrees at those elevations in the Monarchs'
dominion of Oyamel woods. But it does build on studies during a time
much less had been determined about the 'compass', at that time which
suspected but did not confirm this at least as far back as Herman, WS
(1981)
http://www.biolbull.org/content/160/1/89.full.pdf
Best wishes
Doug
Chip Taylor
Feb 21, 2013, 6:02:15 PM2/21/13
to
Doug: You have lots of points here and I don't have time to answer them all.
Here are some notes based on experiments that
we've done and those by Reppert and his team.
Diapsue and the migration are not linked. They
are two separate things. True, diapause precedes
the migration in the fall but if you take
migratory monarchs and break the diapause - they
continue to show migratory behavior - for how
long we don't know. Also, returning migrants are
not in diapause by the time they reach TX.
As to the implications of the recent findings -
yes, they could spell bad news BUT, there is
still a lot we don't know about monarch behavior.
To stay non-reproductive, monarchs exhibit a
variety of behaviors to stay cool - that is to
keep the JH from activating the reproductive
system. They might well ramp up these behaviors
by seeking the coolest and darkest parts of the
forests if it gets progressively warmer at the ow
sites. (A problem of course is that even the
intact forests are becoming progressively
degraded. On my last trip to MX, I was surprised
to see how little understory remained at the main
ow site.)
As to the temps - you need to consult the actual
records from the ow sites as reported by Brower
in several papers, The surrogate temps for the
region are different, often being both lower and
higher depending on the location of the recording
station..
I'll send you a pdf of the most recent article -
and if anyone else would like to see it - just
send me an email.
Chip
Here are some notes based on experiments that
we've done and those by Reppert and his team.
Diapsue and the migration are not linked. They
are two separate things. True, diapause precedes
the migration in the fall but if you take
migratory monarchs and break the diapause - they
continue to show migratory behavior - for how
long we don't know. Also, returning migrants are
not in diapause by the time they reach TX.
As to the implications of the recent findings -
yes, they could spell bad news BUT, there is
still a lot we don't know about monarch behavior.
To stay non-reproductive, monarchs exhibit a
variety of behaviors to stay cool - that is to
keep the JH from activating the reproductive
system. They might well ramp up these behaviors
by seeking the coolest and darkest parts of the
forests if it gets progressively warmer at the ow
sites. (A problem of course is that even the
intact forests are becoming progressively
degraded. On my last trip to MX, I was surprised
to see how little understory remained at the main
ow site.)
As to the temps - you need to consult the actual
records from the ow sites as reported by Brower
in several papers, The surrogate temps for the
region are different, often being both lower and
higher depending on the location of the recording
station..
I'll send you a pdf of the most recent article -
and if anyone else would like to see it - just
send me an email.
Chip
Paul Cherubini
Feb 21, 2013, 9:14:46 PM2/21/13
to
Doug and Chip:
I havn't read the original paper yet, but from reading the
abstract, fall migrant monarchs exposed to 24 days of chilly
temperatures flew north when tethered in a flight simulator:
http://reppertlab.org/tools/flight-simulator/
So the study does not actually demonstrate the direction(s)
the cold treated butterflies would fly if they were released
into the wild. So I do not see how the authors can legitimately
make this claim: "Our discovery that coldness triggers the
the science news articles and the lead author of the study
are telling the public:
http://www.sciencedaily.com/releases/2013/02/130221141259.htm
Coldness Triggers Northward Flight in Monarch Butterflies:
Migration Cycle May Be Vulnerable to Global Climate Change
"The temperature of the microenvironment at the overwintering
sites is a critical component for the completion of the migration
cycle," said Steven M. Reppert, MD, professor of neurobiology
and senior author of the study. "Without this thermal
stimulus, the annual migration cycle would be broken,
and we could have lost one of the most intriguing
biological phenomena in the world."
and
"The more we learn, the clearer it becomes that the
monarch migration is a uniquely fragile biological
process," said Reppert. "Understanding how it
works means we'll be better able to protect this
iconic system from external threats such as global
warming."
Googling "monarch butterfly cold" will bring up
many more articles about this study.
Paul Cherubini
El Dorado, Calif.
I havn't read the original paper yet, but from reading the
abstract, fall migrant monarchs exposed to 24 days of chilly
temperatures flew north when tethered in a flight simulator:
http://reppertlab.org/tools/flight-simulator/
So the study does not actually demonstrate the direction(s)
the cold treated butterflies would fly if they were released
into the wild. So I do not see how the authors can legitimately
make this claim: "Our discovery that coldness triggers the
northward flight direction in spring remigrants solves one of the
long-standing mysteries of the monarch migration."
Now on the basis of that crude experiment, look at what
long-standing mysteries of the monarch migration."
the science news articles and the lead author of the study
are telling the public:
http://www.sciencedaily.com/releases/2013/02/130221141259.htm
Coldness Triggers Northward Flight in Monarch Butterflies:
Migration Cycle May Be Vulnerable to Global Climate Change
"The temperature of the microenvironment at the overwintering
sites is a critical component for the completion of the migration
cycle," said Steven M. Reppert, MD, professor of neurobiology
and senior author of the study. "Without this thermal
stimulus, the annual migration cycle would be broken,
and we could have lost one of the most intriguing
biological phenomena in the world."
and
"The more we learn, the clearer it becomes that the
monarch migration is a uniquely fragile biological
process," said Reppert. "Understanding how it
works means we'll be better able to protect this
iconic system from external threats such as global
warming."
Googling "monarch butterfly cold" will bring up
many more articles about this study.
Paul Cherubini
El Dorado, Calif.
Stan Gorodenski
Feb 21, 2013, 10:39:43 PM2/21/13
to
On 2/21/2013 7:11 PM, Paul Cherubini wrote:
> Doug and Chip:
>
> I havn't read the original paper yet, but from reading the
> abstract, fall migrant monarchs exposed to 24 days of chilly
> temperatures flew north when tethered in a flight simulator:
> http://reppertlab.org/tools/flight-simulator/
>
> So the study does not actually demonstrate the direction(s)
> the cold treated butterflies would fly if they were released
> into the wild. So I do not see how the authors can legitimately
> make this claim: "Our discovery that coldness triggers the
> northward flight direction in spring remigrants solves one of the
> long-standing mysteries of the monarch migration."
>
determine the migratory patterns of the Monarch being criticized (by
researchers of the status of these authors) for somewhat the same reasons?
Stan
Chuck Vaughn
Feb 21, 2013, 11:07:36 PM2/21/13
to
What bothers me about press releases like this is the lack of historical perspective and the apparent lack of curiosity about the past.
I don't know the answers to these questions but I think about them anyway.
How long has the monarch migration been going on?
Does it extend back to the last ice age and beyond?
How was it impacted by earlier warm periods like the Medieval Warm Period, the Roman Warm Period and earlier warm periods, all of which have been shown to be as warm or warmer than today?
I assume monarchs were around during the last ice age. What was their behavior then? Did the migration shift south?
Assuming the speculation part of this study is correct, did the migration stop during past periods of higher temperatures? If they did stop then they must have resumed during cooler periods. Why would it be assumed that if they stopped in a warmer world today that they could never resume in a future cooler period?
Is it possible that the migration just shifts north during warmer periods?
Why do the authors of a paper that must have had required a lot work feel it necessary to add what appears to many of us as speculation in a press release? Are the direct results of the work not interesting enough?
Maybe the subject of research for their next paper should be to determine at what temperature the migration stops. Or did they do this here?
Until someone can explain to me how the migration persisted through warmer and cooler periods in the past but can now no longer do so, I can't help but be skeptical of the fragility of the migration.
If my idea that the migration shifts north or south with temperature could be proven correct then that would be a strong argument for a robust migration.
Chuck
I don't know the answers to these questions but I think about them anyway.
How long has the monarch migration been going on?
Does it extend back to the last ice age and beyond?
How was it impacted by earlier warm periods like the Medieval Warm Period, the Roman Warm Period and earlier warm periods, all of which have been shown to be as warm or warmer than today?
I assume monarchs were around during the last ice age. What was their behavior then? Did the migration shift south?
Assuming the speculation part of this study is correct, did the migration stop during past periods of higher temperatures? If they did stop then they must have resumed during cooler periods. Why would it be assumed that if they stopped in a warmer world today that they could never resume in a future cooler period?
Is it possible that the migration just shifts north during warmer periods?
Why do the authors of a paper that must have had required a lot work feel it necessary to add what appears to many of us as speculation in a press release? Are the direct results of the work not interesting enough?
Maybe the subject of research for their next paper should be to determine at what temperature the migration stops. Or did they do this here?
Until someone can explain to me how the migration persisted through warmer and cooler periods in the past but can now no longer do so, I can't help but be skeptical of the fragility of the migration.
If my idea that the migration shifts north or south with temperature could be proven correct then that would be a strong argument for a robust migration.
Chuck
MexicoDoug
Feb 21, 2013, 11:59:29 PM2/21/13
to
Paul, Chip;
Chip, thanks for clarifying some of my questions. The pdf you so
kindly sent didn't come though successfully for me so if you can just
give us a link that might work better, or give it another shot (mine
came in as a 2 MB+ web-attachment when it should have been I think a
~950 KB pdf.
As Chip and I think all of us agree it will be helpful to go through
the real data for which Monarchs are exposed that's already out there
to see if it's reasonable to make sweeping statements or not. I just
hope Chip had any suspended-autumn Monarchs released in Texas tagged so
he can tell us later where they really ended up. Still the tethered
flight set up is cool, Paul, you ought to get one of those to play with!
IMO, regarding the comment on the 'danger' statements, the Journal
chosen for the publication (it wasn't an entomology journal) was more
from the perspective of a biochemical/neural signaling + pathway
interest, which seems to be the research groups principal interest.
Frequently authors are able to slip in these sorts of statements when
the peer reviewers aren't concerned with such statements and just skip
them unscathed - more worried about scientific verification (as in
letting a real error get by on their watch) rather than appearing to be
a nitpick at fluff that is common in many papers when authors
contemplate the furthest reaching implications of their work from a
purposefully biased viewpoint.
With Monarchs, I'm not even sure if there are enough independent
researchers available in that even top tier journals would have
difficulty putting together an unbiased, anyomous review panel
sensitive to this. Unless I'm missing something, all that is here is a
statement that says the Monarchs need to experience a cold to warm
switch in temperatures to change flight direction. At the moment that
doesn't sound to me like a novel idea since other non-migratory
populations have already been discussed on the list show evidence of
what happens when they lose their cold stimulus.
Best wishes
Doug
.
-----Original Message-----
From: Paul Cherubini <mon...@saber.net>
To: Leps List <Lep...@mailman.yale.edu>
Sent: Thu, Feb 21, 2013 9:14 pm
Subject: Re: [Leps-l] monarchs, reversal of orientation and
overwintering temperatures
Chip, thanks for clarifying some of my questions. The pdf you so
kindly sent didn't come though successfully for me so if you can just
give us a link that might work better, or give it another shot (mine
came in as a 2 MB+ web-attachment when it should have been I think a
~950 KB pdf.
As Chip and I think all of us agree it will be helpful to go through
the real data for which Monarchs are exposed that's already out there
to see if it's reasonable to make sweeping statements or not. I just
hope Chip had any suspended-autumn Monarchs released in Texas tagged so
he can tell us later where they really ended up. Still the tethered
flight set up is cool, Paul, you ought to get one of those to play with!
IMO, regarding the comment on the 'danger' statements, the Journal
chosen for the publication (it wasn't an entomology journal) was more
from the perspective of a biochemical/neural signaling + pathway
interest, which seems to be the research groups principal interest.
Frequently authors are able to slip in these sorts of statements when
the peer reviewers aren't concerned with such statements and just skip
them unscathed - more worried about scientific verification (as in
letting a real error get by on their watch) rather than appearing to be
a nitpick at fluff that is common in many papers when authors
contemplate the furthest reaching implications of their work from a
purposefully biased viewpoint.
With Monarchs, I'm not even sure if there are enough independent
researchers available in that even top tier journals would have
difficulty putting together an unbiased, anyomous review panel
sensitive to this. Unless I'm missing something, all that is here is a
statement that says the Monarchs need to experience a cold to warm
switch in temperatures to change flight direction. At the moment that
doesn't sound to me like a novel idea since other non-migratory
populations have already been discussed on the list show evidence of
what happens when they lose their cold stimulus.
Best wishes
Doug
.
-----Original Message-----
From: Paul Cherubini <mon...@saber.net>
To: Leps List <Lep...@mailman.yale.edu>
Sent: Thu, Feb 21, 2013 9:14 pm
Subject: Re: [Leps-l] monarchs, reversal of orientation and
overwintering temperatures
MexicoDoug
Feb 22, 2013, 12:16:37 AM2/22/13
to
"At the moment that doesn't sound to me like a novel idea since other
non-migratory
populations have already been discussed on the list show evidence of
what happens when they lose their cold stimulus."
Oops - just to clarify. I am not refering to the general paper
non-migratory
populations have already been discussed on the list show evidence of
what happens when they lose their cold stimulus."
here^^^^^ - the abstract seems great - I am only referring to the
political fallout from the claim from those authors some list members
object to:
"The temperature of the microenvironment at the overwintering
sites is a critical component for the completion of the migration
cycle,"
"Without this thermal
stimulus, the annual migration cycle would be broken,
and we could have lost one of the most intriguing
biological phenomena in the world."
leave many reasonable readers to draw ridiculous conclusions. Don't
get me wrong - I'll take that paper with or without it ;-). Anyway, it
seems that was more from the press release ...
Best Doug
Paul Cherubini
Feb 22, 2013, 12:36:01 AM2/22/13
to
On Feb 21, 2013, at 8:57 PM, MexicoDoug wrote:
> Still the tethered flight set up is cool, Paul, you
> ought to get one of those to play with!
Doug, the tethered flight set up has never been shown to
> Still the tethered flight set up is cool, Paul, you
> ought to get one of those to play with!
reliably reveal the migratory flight directions of free
living monarchs in various parts of the USA.
Example: The actual fall migratory flight directions of
monarchs in Colorado, New Mexico and Arizona
in September are known to range from Northwest to Southeast
like this:
http://img690.imageshack.us/img690/9093/northamericat.jpg
http://swmonarchs.org/az-recoveries_wild.php
even when the butterflies have been tagged and released
at the same time on the same day (which rules out
the "they were blown this or that way" theory).
But the tethered flight simulator would likely show the
butterflies heading only southwest which is not what
really happens. To date the researchers who use the tethered
flight simulator havn't shown any interest in testing it
out in States like Colorado, New Mexico and Arizona
in order to find how the butterflies would orient.
MexicoDoug
Feb 22, 2013, 1:20:34 AM2/22/13
to
Paul,
Well, on the positive side, I see a very interesting paper out there to
find out, if your contention is true, what exactly it is about the
flight simulator that would cause statistically significant results at
all, considering it is unlikely the butterfly doesn't have a roadmap.
What about the "disappearance bearing" method? Do you know of any
evidence that the initial bearing is too spurrious as the butterfly
acclimatizes to the stimuli it probably needs some time to process, or
imight it more likely match the true direction of the individuals
released in their future flight plan?
Best wishes
Doug
-----Original Message-----
From: Paul Cherubini <mon...@saber.net>
To: Leps List <Lep...@mailman.yale.edu>
Sent: Fri, Feb 22, 2013 12:35 am
Subject: Re: [Leps-l] monarchs, reversal of orientation and
overwintering temperatures
Well, on the positive side, I see a very interesting paper out there to
find out, if your contention is true, what exactly it is about the
flight simulator that would cause statistically significant results at
all, considering it is unlikely the butterfly doesn't have a roadmap.
What about the "disappearance bearing" method? Do you know of any
evidence that the initial bearing is too spurrious as the butterfly
acclimatizes to the stimuli it probably needs some time to process, or
imight it more likely match the true direction of the individuals
released in their future flight plan?
Best wishes
Doug
-----Original Message-----
From: Paul Cherubini <mon...@saber.net>
To: Leps List <Lep...@mailman.yale.edu>
Sent: Fri, Feb 22, 2013 12:35 am
Subject: Re: [Leps-l] monarchs, reversal of orientation and
overwintering temperatures
MexicoDoug
Feb 22, 2013, 1:47:15 AM2/22/13
to
Chip,
Are these <0.3 gram bug-microtransmitter trackers feasible for any of
these studies?
http://www.mpg.de/592464/pressRelease20090724
http://www.popularmechanics.com/science/environment/4342060
http://www.emerging-technologies-news.info/index.php/new-technology/global-tracking/
Are these <0.3 gram bug-microtransmitter trackers feasible for any of
these studies?
http://www.mpg.de/592464/pressRelease20090724
http://www.popularmechanics.com/science/environment/4342060
http://www.emerging-technologies-news.info/index.php/new-technology/global-tracking/
Paul Cherubini
Feb 22, 2013, 2:40:33 AM2/22/13
to
On Feb 21, 2013, at 10:18 PM, MexicoDoug wrote:
> what exactly it is about the flight simulator that
> would cause statistically significant results at all,
> considering it is unlikely the butterfly doesn't have
> a roadmap.
To locate the refrigerator like climate of the Mexican overwintering
> what exactly it is about the flight simulator that
> would cause statistically significant results at all,
> considering it is unlikely the butterfly doesn't have
> a roadmap.
highlands or the California coast the monarchs must use multiple
direction finding or modifying cues including some we can only
vaguely imagine like a temperature gradient detecting cue.
Why? Because a southwesterly flight bearing of a fall migrant
monarch in Phoenix, AZ in Sept. would take it into the low deserts
of Baja California which has too warm of a winter
climate to keep it alive all winter.
So the butterflies must be detecting environmental information
in Phoenix area that overides their usual time compensated
Southwesterly sun compass and causes them to fly either
West or Northwest towards the California coast or southeast
towards central Mexico.
The simulator may only allow the butterflies to use their
usual time compensated southwesterly sun compass
and interfere with the other cues that modify or override
the sun compass. So that is why I think the butterflies might
still orient to the Southwest (the wrong way) if tested in
the simulator in Phoenix in September.
> What about the "disappearance bearing"
> method?
the scientists who champion the disappearance
bearing method (e.g. Chip Taylor) have shown no interest in
testing it out in areas like Arizona where the butterflies
don't normally head southwest in September.
MexicoDoug
Feb 22, 2013, 5:02:31 AM2/22/13
to
"modifying cues including some we can only
vaguely imagine like a temperature gradient detecting cue."
I can see this happening if there is a transition from lake to desert,
vaguely imagine like a temperature gradient detecting cue."
but transition in nature are not always so easily distinguished - would
you agree? Though, for the purposes of the experiment the
Massachusetts group in Chip's links, getting the basic orientation out
of the flight simulator then might actually be preferred in those
instances since the obstacles are just going to muck up the results
unnecessarily in one sense.
It's hard to imagine a too complex sub-gram flying weather station for
one butterfly to be smarter than NOAA, so it would probably not to be
that difficult to desigh some experiments maybe best with those flight
simulators and head source, humidifier/dehumidifier, etc. if what you
say is true, to observe orientation as a function of gradients in
controlled conditions. Also, in the field, I've seen Monarch's
abruptly change direction when hitting the Sierra Madre Oriental and
they are good both at climbing as well as paralleling it somehow with a
tip that a notch or pass is up ahead. This makes them more complex
than a simple robot having a switch in each antenna and each time one
registers to, e.g., go consistently (counter)clockwise, or not if your
example is real about the low desert, on one way of the migration
journey. But I've always assumed that the first travelers did the hard
trial and error work and like ants communicated to others since they
know how to swarm into colonies. I don't know enough about ants but
they exhibit similar behaviors in some instances to Monarchs and it is
possibly done by trial and error (smaller distances but ...) plus
chemical signaling between or left for others which strangely I've
never heard mentioned whern Monarchs are discussed. I don't know how
effective this would be in the winds but it is also easily testable.
Thanks for your perspectives
Doug
-----Original Message-----
From: Paul Cherubini <mon...@saber.net>
To: Leps List <Lep...@mailman.yale.edu>
-----Original Message-----
From: Paul Cherubini <mon...@saber.net>
To: Leps List <Lep...@mailman.yale.edu>
Sent: Fri, Feb 22, 2013 2:40 am
Subject: Re: [Leps-l] monarchs, reversal of orientation and
overwintering temperatures
Subject: Re: [Leps-l] monarchs, reversal of orientation and
overwintering temperatures
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