# colors in tropical frogs



## Julio (Oct 8, 2007)

How Do Tropical Frogs Get Their Stunning Colors? | Science & Nature | Smithsonian Magazine


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## Reef_Haven (Jan 19, 2011)

Her theory on mate selection seems to be contradicted by this research.

http://www.dendroboard.com/forum/science-conservation/96409-unfussy-female-darts-nat-geo.html


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## aspidites73 (Oct 2, 2012)

Reef_Haven said:


> Her theory on mate selection seems to be contradicted by this research.
> 
> http://www.dendroboard.com/forum/science-conservation/96409-unfussy-female-darts-nat-geo.html


So, how is one to know which is more correct, if any?


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## SDRiding (Jul 31, 2012)

The unfussy darts study was the first to contradict previous conclusions. So I'm sure more studies will pop up to test these findings. Just more pieces to the puzzle. I wouldn't try to draw a definitive answer from it just yet.



aspidites73 said:


> So, how is one to know which is more correct, if any?


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## hypostatic (Apr 25, 2011)

aspidites73 said:


> So, how is one to know which is more correct, if any?


Have both studies been published in journal? Usually, if its in a research paper, there will be a methods & materials section which will tell you how the research was gathered, and there would also be available the raw data that was gathered (how many frogs did what, etc..)

EDIT:

Here's the " non-choosy females" paper:
http://www.frontiersinzoology.com/content/10/1/29

So here's the publication page of the scientist quoted in the Smithsonian article:
http://www.bio.utexas.edu/research/cummingslab/publications.html
I think it would be either this paper: http://www.bio.utexas.edu/research/cummingslab/pdfs/Cummings_Crothers_EvolEcol_2013.pdf
Or this paper: http://www.bio.utexas.edu/research/cummingslab/pdfs/Crothers_Cummings_2013_AmNat.pdf


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## cml1287 (Mar 29, 2012)

Julio said:


> How Do Tropical Frogs Get Their Stunning Colors? | Science & Nature | Smithsonian Magazine


I think the take away from this particular pub is that color and toxicity are directly correlated. This she showed in the lab. Toward the bottom of the paper, I think it's more speculation.


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## hypostatic (Apr 25, 2011)

From the Smithsonian article:



> And while birds are good at telling different colors apart, they’re not so hot at detecting different levels of brightness. So the intensity of the frog’s coloration must be about sex, Cummings thought.


I find this hard to believe. Especially in species like the birds of paradise, where both color and brightness are important factors in mate selection by females


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## aspidites73 (Oct 2, 2012)

Cool! Now we have a discussion. Prior, all we had were two different opinions, and no one could learn anything.



SDRiding said:


> The unfussy darts study was the first to contradict previous conclusions. So I'm sure more studies will pop up to test these findings. Just more pieces to the puzzle. I wouldn't try to draw a definitive answer from it just yet.


How do we know it's the first? If it is the first, I would tend to agree that more studies will have to be done but, was this even a scientific study to begin with? It was only 20 frogs. Does that say anything about the results?



hypostatic said:


> Have both studies been published in journal? Usually, if its in a research paper, there will be a methods & materials section which will tell you how the research was gathered, and there would also be available the raw data that was gathered (how many frogs did what, etc..)


Thank you for the links! They are much more informative than the 2 articles first presented in this thread, that were merely someone's (the author's) interpretation. It is and interesting topic. Unfortunately, I have more questions than answers. Maybe they were simply choosing the closest mate because there were strange animals (the people doing the study) following them. Which is a stronger instinct, the desire to mate, or the desire to survive? What do you think?



cml1287 said:


> I think the take away from this particular pub is that color and toxicity are directly correlated. This she showed in the lab. Toward the bottom of the paper, I think it's more speculation.


Interesting! Agreed that it seems to show a correlation, but correlation does not imply causation. Also, it was only 20 frogs. That hardly seems enough to make a statement on behalf of an entire population. Even if we were to accept the lab results as true; does it really mean anything other than more data needs to be collected? Would you put your reputation on the line by telling someone that Pumilio are, say, active during certain hours because you had 20 of them and they all fit that description?


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## cml1287 (Mar 29, 2012)

aspidites73 said:


> Interesting! Agreed that it seems to show a correlation, but correlation does not imply causation. Also, it was only 20 frogs. That hardly seems enough to make a statement on behalf of an entire population. Even if we were to accept the lab results as true; does it really mean anything other than more data needs to be collected? Would you put your reputation on the line by telling someone that Pumilio are, say, active during certain hours because you had 20 of them and they all fit that description?


Where are you seeing that the study consisted of only 20 frogs?


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## aspidites73 (Oct 2, 2012)

cml1287 said:


> Where are you seeing that the study consisted of only 20 frogs?


My apologies. The article linked by Hypostatic actually says the study group was 198. I confused it with the other study.

Edit: The Smithsonian article is using the data collected in a study on color/toxicity. So, the question I asked is now framed as if it included 198 individuals.


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## Ed (Sep 19, 2004)

Her study ignores the fact that there is huge variation within a location over time for alkaloid content Spatial and temporal patterns of alkaloid variation in the poison frog Oophaga pumilio in Costa Rica and Panama over 30 years 

One study indicates that females tend to have higher concentrations of alkaloids Sex-related Differences in Alkaloid Chemical Defenses of the Dendrobatid Frog Oophaga pumilio from Cayo Nancy, Bocas del Toro, Panama 

Some comments 

Ed


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## aspidites73 (Oct 2, 2012)

Ed said:


> Her study ignores the fact that there is huge variation within a location over time for alkaloid content Spatial and temporal patterns of alkaloid variation in the poison frog Oophaga pumilio in Costa Rica and Panama over 30 years
> 
> One study indicates that females tend to have higher concentrations of alkaloids Sex-related Differences in Alkaloid Chemical Defenses of the Dendrobatid Frog Oophaga pumilio from Cayo Nancy, Bocas del Toro, Panama
> 
> ...


Thanks, Ed. I must admit, I am trying to incite a stimulating conversation. The two articles which began this thread seemed good ones to debate, as they had a few assumptions on the part or their writers, respectively.


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## Ed (Sep 19, 2004)

aspidites73 said:


> Thanks, Ed. I must admit, I am trying to incite a stimulating conversation. The two articles which began this thread seemed good ones to debate, as they had a few assumptions on the part or their writers, respectively.


Sorry, 

I'll go back into the darkness... 

Ed


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## cml1287 (Mar 29, 2012)

If they sampled 198 individuals, would you consider that to be a sufficient sample size? I'm not exactly sure how power analysis works, but that could be the reason for the seemingly small sample size.


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## aspidites73 (Oct 2, 2012)

Ed said:


> Sorry,
> 
> I'll go back into the darkness...
> 
> Ed


It wasn't meant that way. Although, after re-reading, it sure does sound that way. My apologies. What I did mean was that I was purposeful in my citing of said articles despite the fact they were flawed. Someone else brought them up, I saw an opportunity to make it interesting, and took it.

EDIT: sp.


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## aspidites73 (Oct 2, 2012)

cml1287 said:


> If they sampled 198 individuals, would you consider that to be a sufficient sample size? I'm not exactly sure how power analysis works, but that could be the reason for the seemingly small sample size.


It is more sufficient, especially for the example I gave of using personal experience and standing behind one's reputation. I would definitely be more inclined to offer advice if I had the experience one could get from having 198 animals. Scientifically significant is still a big no.

In the top article Ed linked, their sample size was "53 different populations from over 30 years of research". That is scientific significance. Is there an in between, of course. 198 is not it.

Forgetting those points for a moment, do you have any points to discuss? I'm only fishing for a discussion. No ulterior motives here,


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## JasonE (Feb 7, 2011)

The sample size is so small, its hard to take it seriously. Also, don't we have a way to analyse the toxicity on a quantifiable scale? Her theory on color and toxicity might be true, but she doesn't have enough evidence to back it up. 

Sent from my SAMSUNG-SGH-I337 using Tapatalk 4


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## cbreon (Apr 25, 2005)

Here is another article that was recently posted on DartDen:

http://www.jasonleebrown.org/jasonl...rown_2013_Spatiotemporally_explict_models.pdf

It covers some of the subjects above, and seems much more thorough. I wouldnt be suprised if they cited the two studies that Ed linked, they seem to say some of the same things...


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## MonarchzMan (Oct 23, 2006)

I came in late, but given that my current study is wrapped around this one, I'll weigh in here or there.



hypostatic said:


> I find this hard to believe. Especially in species like the birds of paradise, where both color and brightness are important factors in mate selection by females


You must understand, however, that the difference in brightness is minute. It's not like looking at pastel yellow compared to goldenrod yellow. I asked Molly about this, and she said that it is apparent when you have bright and dull frogs next to each other, but otherwise it is difficult to discern (she was able to discern differences using highly sensitive spectrometry).



Ed said:


> Her study ignores the fact that there is huge variation within a location over time for alkaloid content Spatial and temporal patterns of alkaloid variation in the poison frog Oophaga pumilio in Costa Rica and Panama over 30 years
> 
> One study indicates that females tend to have higher concentrations of alkaloids Sex-related Differences in Alkaloid Chemical Defenses of the Dendrobatid Frog Oophaga pumilio from Cayo Nancy, Bocas del Toro, Panama
> 
> ...


I don't know that her study does ignore it, actually. I don't think that the two are necessarily comparable, to be honest. We know, for example, that color is somewhat diet-based (talk to anyone who has orange/red frogs). So, it is possible that colors change in accordance with differences in diet (and thus toxicity). Steven's paper doesn't cover that portion, so I don't know that one paper invalidates the other.

I'm not familiar with the Solarte paper (I'll have to check it out), but I also don't think that necessarily invalidates her conclusions either since her work relate to males more so than females.



JasonE said:


> The sample size is so small, its hard to take it seriously. Also, don't we have a way to analyse the toxicity on a quantifiable scale? Her theory on color and toxicity might be true, but she doesn't have enough evidence to back it up.


I will apologize in advance if I seem a bit antagonistic here (not intended, but this is something I feel rather strongly about). 200 individuals is not a small sample size, not by a long shot. Having actually helped out Molly with the behavioral experiments, I can tell you for certain that that is an impressive number. It is not physically feasible to do sample sizes for 1000 or 2000 individuals. Sure, it would be great, but I kid you not, doing that many individuals would take at least a year, if not longer, of constant mate choice trials (I'm talking 8 hours a day, 5 days a week). Something like that is just not feasible. I was in Panama for 3 months helping her with her projects and we were doing mate choice trials daily. And she came back the following year to do more. And I believe even the year after that. I think there is plenty of room for skepticism for her studies (like I said, my research from this past summer is doing some follow up questions to it), but I don't think sample size is one to be skeptical on.

As for toxicity, that is something I'm currently struggling with and I do think Molly has an adequate solution (not ideal, but toxicity is difficult). She awakens mice with a prick to the paw of a diluted toxin extract and waits until the mouse returns to sleep. Time awake is how she quantifies it, and it is a creative way to get to the problem (after all, the more painful something is, the less likely a mouse is going to drift back to sleep). However, these toxins have evolved to be tasted (it is possible that a relatively non-toxic frog can be quite distasteful), but how do you quantify that? Do you force-feed mice (or birds, better yet, since they're the probable predator) toxin extracts? If you do do that, how do you quantify the response? It's not an easy question to answer, and I am actively thinking on it. But currently, Molly's system is well tested and well accepted as a proxy.


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## hypostatic (Apr 25, 2011)

Oh, I have a question about dart frog anatomy. Has anybody studied the rods/cones of dart frogs and measured their excitation spectra?


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## MonarchzMan (Oct 23, 2006)

Short answer is yes. Molly Cummings and Martine Maan were doing that. Long answer, I will have to dig for the paper (if they actually published all of that, not sure, but I seem to recall it). 

Siddiqi also did it (I think Cummings and Maan was meant to be a follow up):

Interspecific and intraspecific views of color signals in the strawberry poison frog Dendrobates pumilio


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## hypostatic (Apr 25, 2011)

Thanks, here we go:










it looks like frog's eyes are pretty similar to human eyes?


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