Imprinting on mothers may drive new species formation in poison dart frogs- What do marrying one's parents, Oedipus complex have to do with evolution? – via Herp Digest

Date: October 3, 2019

Source: Smithsonian Tropical Research Institute

The old saying that people marry their parents may be true for poison dart frogs, and it may even lead to the formation of new species, according to a new study in Nature based on work at the Smithsonian Tropical Research Institute (STRI).

Strawberry poison dart frogs live on the mainland in Panama's Bocas del Toro province and have been isolated on islands in the archipelago that formed during the past 10 million years as sea level rose. Only a single color morph exists on some islands -- orange or green, for example, but on other islands several color morphs exist together, like blue and red frogs.

"In the past, people assumed that this group of brightly colored poison dart frogs were warning predators that their skin is toxic," said Corinne Richards-Zawacki, research associate at STRI and professor of biological sciences at the University of Pittsburgh. "But predators don't seem to care what color the frogs are, at least based on our earlier experiments. That's why we started asking whether the way they choose mates might lead to populations of different colors on different islands.”

The team set up three different situations: baby frogs raised with two parents of the same color (red baby, red parents), baby frogs raised with each parent a different color (red baby, one red and one blue parent) and baby frogs raised by foster parents of a different color (red baby, blue parents). In each case they asked which color the female offspring would choose as mates and which color the male offspring would perceive as a rival.

"We discovered that female frogs with parents of the same color tended to choose mates of that same color, whereas frogs with foster parents of a different color would choose mates the color of the foster parents," said Yusan Yang, who is completing her doctoral thesis at the University of Pitts-burgh. "The same was true for male-male aggression. This tells us that imprinting was more important than genetics when it comes to shaping these behaviors that are based on color.”

When baby frogs were raised with one parent of the same color and one parent of a different color, females chose mates the color of their mother, and males chose rivals the color of their mother, indicating that maternal imprinting was probably more important than paternal imprinting.

They also created a mathematical model showing that male aggression based on imprinting, in concert with female mate choice based on imprinting was enough to cause a scenario to evolve, where like mates with like, which could lead to two color morphs becoming separate species.

"We're fascinated by the idea that behavior can play such an important role in evolution," Richards-Zawacki said.

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Materials provided by Smithsonian Tropical Research Institute. Note: Content may be edited for style and length.

Journal Reference:

1. Yusan Yang, Maria R. Servedio, Corinne L. Richards-Zawacki. Imprinting sets the stage for speciation. Nature, 2019; 574 (7776): 99 DOI: 10.1038/s41586-019-1599-z

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Smithsonian Tropical Research Institute. "Imprinting on mothers may drive new species formation in poison dart frogs: What do marrying one's parents, Oedipus complex have to do with evolution?." ScienceDaily. ScienceDaily, 3 October 2019. <www.sciencedaily.com/releases/2019/10/191003135707.htm>.

Imprinting on mothers may drive new species formation in poison dart frogs- What do marrying one's parents, Oedipus complex have to do with evolution? - via Herp Digest

Date: October 3, 2019

Source: Smithsonian Tropical Research Institute

The old saying that people marry their parents may be true for poison dart frogs, and it may even lead to the formation of new species, according to a new study in Nature based on work at the Smithsonian Tropical Research Institute (STRI).

Strawberry poison dart frogs live on the mainland in Panama's Bocas del Toro province and have been isolated on islands in the archipelago that formed during the past 10 million years as sea level rose. Only a single color morph exists on some islands -- orange or green, for example, but on other islands several color morphs exist together, like blue and red frogs.

"In the past, people assumed that this group of brightly colored poison dart frogs were warning predators that their skin is toxic," said Corinne Richards-Zawacki, research associate at STRI and professor of biological sciences at the University of Pittsburgh. "But predators don't seem to care what color the frogs are, at least based on our earlier experiments. That's why we started asking whether the way they choose mates might lead to populations of different colors on different islands.”

The team set up three different situations: baby frogs raised with two parents of the same color (red baby, red parents), baby frogs raised with each parent a different color (red baby, one red and one blue parent) and baby frogs raised by foster parents of a different color (red baby, blue parents). In each case they asked which color the female offspring would choose as mates and which color the male offspring would perceive as a rival.

"We discovered that female frogs with parents of the same color tended to choose mates of that same color, whereas frogs with foster parents of a different color would choose mates the color of the foster parents," said Yusan Yang, who is completing her doctoral thesis at the University of Pitts-burgh. "The same was true for male-male aggression. This tells us that imprinting was more important than genetics when it comes to shaping these behaviors that are based on color.”

When baby frogs were raised with one parent of the same color and one parent of a different color, females chose mates the color of their mother, and males chose rivals the color of their mother, indicating that maternal imprinting was probably more important than paternal imprinting.

They also created a mathematical model showing that male aggression based on imprinting, in concert with female mate choice based on imprinting was enough to cause a scenario to evolve, where like mates with like, which could lead to two color morphs becoming separate species.

"We're fascinated by the idea that behavior can play such an important role in evolution," Richards-Zawacki said.

Story Source:

Materials provided by Smithsonian Tropical Research Institute. Note: Content may be edited for style and length.

Journal Reference:

1. Yusan Yang, Maria R. Servedio, Corinne L. Richards-Zawacki. Imprinting sets the stage for speciation. Nature, 2019; 574 (7776): 99 DOI: 10.1038/s41586-019-1599-z

Cite This Page:

• MLA
• APA
• Chicago

Smithsonian Tropical Research Institute. "Imprinting on mothers may drive new species formation in poison dart frogs: What do marrying one's parents, Oedipus complex have to do with evolution?." ScienceDaily. ScienceDaily, 3 October 2019. 

<www.sciencedaily.com/releases/2019/10/191003135707.htm>.

For Poison Dart Frogs, Markings Matter When It Comes to Survival An experiment found that white-striped frogs were less effective at scaring off predators than frogs with yellow stripes. Yet both populations are thriving. - via Herp Digest

By Veronique Greenwood, New York Times

Sept. 12, 2019

The fanciful colored markings of poison dart frogs are a warning to predators: If you eat me, you’ll regret it.

These tiny, colorful creatures secrete bitter toxins in their skin, and birds have come to associate their distinctive markings with danger. The frogs’ chemical defenses can cause swelling, paralysis and sometimes even death. Their markings are so distinctive that it seems any frog trying out a new look would be running a serious risk.

And yet, new markings do crop up. Dyeing poison dart frogs in one part of French Guiana usually are blue and black with yellow markings. But in the nearby Mont Grand Matoury nature preserve, they have white stripes. Scientists curious about how this alternative coloration was working out ran a series of experiments, and reported some surprising results last week in Proceedings of the National Academy of Science.

The white-striped frogs were not as effective at scaring off predators as their yellow brethren, they found. But they still managed to avoid being outcompeted by the fitter, more threatening yellow-striped frogs, perhaps in part because of their location.

The researchers began by setting out more than 2,000 clay models of frogs — some white-striped, some yellow-striped and some that were solid-colored — in both the Matoury nature preserve and in the Kaw Mountains, about 30 miles away, where a population of yellow-striped frogs lives.

When they collected the models later, they looked for gouges and scrapes that indicated a bird  attack. They expected that birds in the Matoury preserve would avoid white-striped frogs while birds in the Kaw Mountains would steer clear of the ones with yellow stripes.

They were surprised to find that this was not the case. In Matoury, the white-striped frogs were attacked most, while in the Kaw Mountains frogs of all patterns were attacked about equally.

“This had us scratching our heads,” said J.P. Lawrence, a postdoctoral researcher at the University of California, Irvine, and an author of the new paper.

Bright warning colors on poison dart frogs also act as camouflage

June 4, 2018, University of Bristol

Poison dart frogs are well known for their deadly toxins and bright colours, which have made them a classic example of warning coloration.

The Dyeing Dart Frog, for example, is highly toxic and warns its predators with a bright yellow-and-black pattern.

However, new research led by scientists at the University of Bristol has revealed that the colour pattern does more than simply signal "danger". Counterintuitively, it also works as camouflage.

Lead author, Jim Barnett completed this research, published today in the journal Proceedings of the National Academy of Sciences, while studying for a Ph.D. at Bristol. He is now based at McGill University in Canada.

He said: "Effective as warning signals are, it's not necessarily the best strategy to be maximally conspicuous.

"Certain predators have evolved tolerance of toxins that would be deadly for humans, and some individual predators may have not encountered the warning signal prey before (a dangerous mistake for the predator, but also for the frog).

"So, colour patterns that could be distinctive close-up, but work as camouflage from a distance, would provide a clear advantage."

Combining fieldwork in the jungles of French Guiana, computational modelling, and laboratory visual search experiments, Barnett and colleagues from the University of Bristol's School of Biological Sciences and the School of Experimental Psychology investigated how the Dyeing Dart Frog uses its colours to balance the benefits of effective warning signals with the advantages of concealment.

They found that, despite being highly conspicuous at close range, the particular colours and their arrangement allow the pattern to blend together to form background-matching camouflage when viewed from a distance.

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Why poison dart frogs don't poison themselves

September 5, 2017 by Bob Yirka report

 (Phys.org)—A pair of researchers with the State University of New York has found the source of poison dart frogs' immunity from their own poison. In their paper published in Proceedings of the National Academy of Sciences, Sho-Ya Wang and Ging Kuo Wang describe testing frog muscle-derived amino acids in rat muscles to determine if one of them might be responsible for preventing muscle from seizing.

Poison dart frogs, native to Columbia, are known throughout the world for the application of their poison to blow darts as a weapon. The toxin is produced in the skin gland and one frog holds enough to kill 10 human beings at any one time—the toxin kills by reversing the openings of sodium channels in nerves, which prevents muscles from relaxing. The heart clenches to push blood through the body, but then cannot unclench, preventing it from working.

Prior research has shown that the active ingredient in the toxin is batrachotoxin. To figure out why the dart frogs do not give themselves heart attacks when they produce the chemical, the researchers introduced five naturally occurring amino acid replacements found in the frog's muscles into rat muscles. Doing so, the researchers report, made the rat muscle immune to the effects of batrachotoxin. The researchers then tested the amino acids individually until they found the one that was responsible for the change—N1584T. This finding overturns prior research results that suggested multiple factors were responsible for frog immunity—it shows that the immunity in the frogs comes from a single genetic mutation.

Unfortunately, as with the puffer fish, which was also found to have just one amino acid that protected it from harming itself, this discovery is not likely to offer a path to an antidote for those who fall prey to the effects of dart frog toxin. It might offer new data, however, for those conducting research involving using the toxin as a pain killer.

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Maternally derived chemical defences are an effective deterrent against some predators of poison frog tadpoles (Oophaga pumilio) – via Herp Digest

Biology Letters, 5/21/14

1. Jennifer L. Stynoski1⇑,
2. Georgia Shelton2 and
3. Peter Stynoski3

- Author Affiliations

1. ¹Organization for Tropical Studies, Apartado Postal 676-2050, San Pedro, Costa Rica 
2. ²Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA 
3. ³Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL 61801, USA 
4. e-mail: stynoski@gmail.com

Abstract

Parents defend their young in many ways, including provisioning chemical defences. Recent work in a poison frog system offers the first example of an animal that provisions its young with alkaloids after hatching or birth rather than before. But it is not yet known whether maternally derived alkaloids are an effective defence against offspring predators. We identified the predators of Oophaga pumilio tadpoles and conducted laboratory and field choice tests to determine whether predators are deterred by alkaloids in tadpoles. We found that snakes, spiders and beetle larvae are common predators of O. pumilio tadpoles. Snakes were not deterred by alkaloids in tadpoles. However, spiders were less likely to consume mother-fed O. pumilio tadpoles than either alkaloid-free tadpoles of the red-eyed treefrog, Agalychnis callidryas, or alkaloid-free O. pumilio tadpoles that had been hand-fed with A. callidryas eggs. Thus, maternally derived alkaloids reduce the risk of predation for tadpoles, but only against some predators.

New species of poison dart found in Guyana – By mistake

Scientists found new species without looking

July 2013. Ecotourism and Conservation - Can it work? That was the question a team of scientists from the Senckenberg Research Institute in Dresden were investigating when, by chance, they found a previously undiscovered species of frog that only exists in a very confined area of the so-called Iwokrama Forest.

The Guiana Shield in the north of South America accounts for more than 25 percent of the world's tropical rain forests, and is one of the four remaining extensive pristine forested areas left in the world (Amazon, Congo, Papua New Guinea and Guiana Shield).

Iwokrama study centre

In a study sponsored by the Stiftung Artenschutz [Species Conservation Foundation] and the Verband Deutscher Zoodirektoren [Association of German Zoo Directors], the Dresden team, led by biologists Dr. Raffael Ernst and Monique Hölting investigated whether conservation of amphibians and ecotourism can be reconciled in the forests of Guyana. The investigations are being carried out in close co-operation with the international not-for-profit organization Iwokrama International Centre for Rain Forest Conservation and Development.

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Predators Drive the Evolution of Poison Dart Frogs' Skin Patterns

ScienceDaily (Nov. 21, 2011) — Natural selection has played a role in the development of the many skins patterns of the tiny Ranitomeya imitator poison dart frog, according to a study that will be published in an upcoming edition of American Naturalist by University of Montreal biologist Mathieu Chouteau.

The researcher's methodology was rather unusual: on three occasions over three days, at two different sites, Chouteau investigated the number of attacks that had been made on fake frogs, by counting how many times that had been pecked. Those that were attacked the least looked like local frogs, while those that came from another area had obviously been targeted.

The brightly coloured frogs that we find in tropical forests are in fact sending a clear message to predators: "don't come near me, I'm poisonous!" But why would a single species need multiple patterns when one would do? It appears that when predators do not recognize a poisonous frog as being a member of the local group, it attacks in the hope that it has chanced upon edible prey. "When predators see that their targets are of a different species, they attack. Over the long term, that explains how patterns and colours become uniform in an area," said Bernard Angers, who directed Chouteau's doctoral research.


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