Dendroboard banner
1 - 15 of 15 Posts

·
Registered
Joined
·
4,020 Posts
Discussion Starter · #1 ·
Honestly I have never gone along with the fact that the bright colors are 100% for warning predators. While true, dart frogs follow a similar pattern of evolution like butterflies ...evolving flashy colors to warn predators of their bad taste.

Considering dart frogs are diurnal, I would think they have color vision. And considering they are territorial, Dendrobates could use their coloration more for sexual display.

One reason why I don't totally agree with the warning coloration is because of the myth that every dart frog species can kill you. Marine toads are much more toxic than many Dendrobates (exclude phyllobates), and they certainly are not colorful. There are many other toxic frogs, like Cuban tree frogs that aren't brightly colored.

I was wondering if anybody had a source of any information to test this hypothesis, preferably an article they can send me via email. I'm sure I'm not the only one to think this.
 

·
Registered
Joined
·
1,823 Posts
Just as a side note, I believe all frogs are "toxic" to a degree. Used for defenzive purposes.
 

·
Registered
Joined
·
4,020 Posts
Discussion Starter · #3 ·
Derek, sometimes I think reed frogs are the example of "sexual display." Aren't sexes dimorphic?
 

·
Registered
Joined
·
720 Posts
Scientific studies have shown that dart frogs can see in color. Researchers used different colored lights too see if hybridization would occur among Pumilio frogs and the colored light did confuse the frogs. Color is indicative of region in different dart frogs morphs and the ability to see in color theoretically is connected to the diversity in coloration among different regional populations. Each "morph" is adapted to a particular enviromental niche and thus the coloration differences is a survival adaptation. This is what I get from reading some of the studies and discussing it with my Ecology professor (who studies fish not frogs).
 

·
Registered
Joined
·
1,823 Posts
Rain_Frog said:
Derek, sometimes I think reed frogs are the example of "sexual display." Aren't sexes dimorphic?
Some are, more commonly, Hyperolius argus. But then, some aren't. I've only the one species (H. argus) that is sexually diomorphis, while the others are not. I've been reading on my books that I recieved over the holidays on frogs of africa, so I'll try and find some info.
 

·
Registered
Joined
·
4,020 Posts
Discussion Starter · #8 ·
Interesting. SEveral people here at Dendroboard have hypothesized that different morphs, even if kept together, are most likely going to mate with ones of similar looks. I don't know if that is quite what you mean though Heather. If you can find the source of the experiment, I'd like to read it.

I remember that Bufo periglenes, the now extinct golden toad, was dimorphic.
 

·
Registered
Joined
·
639 Posts
I'm not so sure if I agree with rain frog on the sexual display issue. When dart frogs mate there isn't much showing off of colors, so I don't think that dart frogs use their colors to attract a mate - that's what the male's call and the female's rubbing are for.

I do believe that they can see color - but I'm not so sure that they use color to display themselves. Like in that pumillo experiment - I'm not suprized that they were thrown off because of the color, I mean think about it.... would you be attracted to a person if he/she was purple?

Along with displaying their poisons, I think it plays a role in reproduction in that it prevents hybridization...this would be a useful adaptation for them to have picked up along their evolutionary path because the regions of species overlap. So I guess I agree and disagree with rain frog.
 
G

·
Another question to ask would be what predators actually see in color ? And if the frogs see colors is this so to help in distinguishing morphs or species within themselfs ? Curious how the other sences like smell , hearing and touch play into this ? :?:
 

·
Registered
Joined
·
720 Posts
From what I read, there is little or no difference in vocal sounds among different morphs within a species. Pumilio have been studied extensively, so it is assumed that visual cues play a more important role in mate choice. The above linked paper is one of the ones that I read. In order to access full text of most scientific papers you need access to a University computer that has subscriptions to the scientific journals.
 
G

·
bgexotics said:
From what I read, there is little or no difference in vocal sounds among different morphs within a species.
I would disagree with this statement as there are many different morphs of say D. granuliferus, D. histrionicus, even D. pumilio which have different sounding calls. There were populations of D. granuliferus we found that we swore the sound was an insect, but just had the pattern of a D. granuliferus call just speeded up and more high pitched. There is quite a lot of variations. Christmann notes in his book that there are even slight call differences between what he calls D. sylvaticus and D. histrionicus. He later goes on to explain that he's not sure if the old name (sylvaticus) should actually be another species or not, but there were slight differences in size and call between them. I'm eager to get there and see what he's talking about, but that pesky term 'natural variation' comes to mind.
j
 

·
Registered
Joined
·
720 Posts
That is what I would have thought regarding vocal sounds. I think in the article mentioned before, the researchers stated that there was little difference in vocalization. Possibly they did not perform a thorough analysis of the vocalization since they were more concerned with visual mating cues.
 

·
Registered
Joined
·
4,020 Posts
Discussion Starter · #15 ·
Like zoso said, we must ask which predators see in color the best. Dart frogs are so small, that they probably wouldn't be bothered much by coatis or other small carnivores. Members of the cat family can see in color, but their color vision is much less vibrant than ours.

I think, but I'm not positive, that a dart frog's biggest enemy is other herps and frogs. Ceratophrys frogs are diurnal, and certainly could attempt to ambush a tiny frog as they specialize in eating other anurans.

When I watched National Geographic, I saw a snake spit out a dart frog, but that is only a few incidents when I saw dart frogs on TV.

Of course, toxicity still plays a role with their adaption, but I just don't believe that is the entire story to a dart frogs colors, as many so called "non poisonous frogs" are brightly colored, like Hyperolius. Like Derek mentioned, virtually all frogs secrete at least something to deter predators, even if many predators have evolved to eat them.
 
1 - 15 of 15 Posts
Top