These frogs might change color to avoid confusion during – via Herp Digest

 Yellow means go (away)

By Ellen Airhart 9/20/17 Popular Science

Some male frogs change color for mating season.

Grant Webster

Some frog species have a special strategy for breeding. They gather in a huge group of hundreds or even thousands of frogs. In the pandemonium, the ribbeting rabble can have difficulty distinguishing between males, females, and tennis balls.

A lot of the frogs that have sex en masse also turn yellow during the mating season. Rayna Bell, a research zoologist at the Smithsonian Institute, teamed up with Australian researchers to see if these traits actually tend to come in pairs—and if so, which behavior came first.

The sexy frog pile reproduction strategy presents interesting challenges for the animals involved. Bell compares the slimy jumble to a dark nightclub—no one can see what’s going on. “It gets a little chaotic,” says Bell. Could color changes be meant to help males stand out in the writhing crowd?

In 2012, Bell started researching how the genetics of African reed frogs varied across different areas. She wasn't studying why some species of this frog have males and females that are different colors, but people kept asking her about this sex difference during her research presentations. Then a group of scientists in Australia contacted her to tell her they were interested in pursuing that very inquiry. Thus began a virtual collaboration. “I hope to meet them in person someday,” says Bell.

The research team did not go out into the wild to find colorful frogs for this study. They couldn’t rely on natural history collections, either, since preservatives cause amphibians to turn a universal grayish color. Instead, they drew upon previous observations, hit up the library and gathered old field notes. “We have articles going back hundreds of years that you can’t find on the internet,” says Bell. “The study extended beyond any of our individual expertise.”

The literature investigation revealed that frogs known to temporarily change color during mating season are likely to also join in the crowded bacchanals. The team further supported this connection with a frog ancestry test. They dove through genetic history to discover what evolved first, the group mating strategy or the color change. In most species, the breeding method preceded the temporary hue adjustment. So it seems likely that the color changes evolved to make this method of breeding more successful. In this situation, the males probably aren’t trying to attract females with flashy tones as much as warn other males of their sex, to keep everyone from wasting a precious chance to spread their genes. Of course, this explanation is still in the “probable hypothesis” category, since scientists don’t actually know how this amphibian's vision system works. “We have way more questions than answers at this point,” says Bell. “We don’t know if they can even see these differences.”

Frogs can’t change color within a few seconds like chameleons do. Their little bodies fill with hormones that spread out or cluster the pigments in their skin. For changes that last more than a few months, they may even make additional pigments. Scientists don’t know exactly why frogs turn yellow, but it might be the easiest transition for the frog skin to make or the best signaling color for other frogs, or both.

Even if yellow skin is more of a deterrent for other males than an aphrodisiac for females, these croaking casanovas have other methods to indicate they’re ready to get it on. “The natural variation of frog breeding seen in nature is bizarre,” says Adam Leache, a biologist at the University of Washington. Research has traditionally focused on frog calls—even an amateur herpetologist can identify the pebbles-knocking-together sound of the cricket frog. Frogs that live in noisier areas, such as near a waterfall, sometimes wave or lift up one of their back legs. This wealth of interesting mating rituals have left researchers with a lot to study. “I think that’s fascinating for us to have a better understand of how color works,” says Bell. “It’s showing us that frogs probably have more complicated communication channels.”

Bell says she next hopes to look into the frog visual system, so she can make sure these amphibians can see one another’s sexy yellow hue. “Compared to other types of vertebrates, we don’t know that much about what frogs can see,” she says. Since they live in both water and land over the course of their lifetime, frogs might even give us clues about how our own vision developed. “I think it’s inspiring to think about how nature has evolved all these crazy strategies,” says Bell.

Cope's gray treefrogs meet the cocktail party problem

With hundreds of males calling at the same time, how's a female to choose a mate? Like this.

Date: June 7, 2017

Source: University of Minnesota

You've been there: Trying to carry on a conversation in a room so noisy that the background chatter threatens to drown out the words you hear. Yet somehow your auditory system is able to home in on the message being conveyed by the person you're talking with. The secret to rising above the noise -- a dilemma known in the world of sound science as "the cocktail party problem" -- turns out to lie in its ability to discern patterns in the background noise and selectively ignore such patterns, according to a new study published in Current Biology earlier this month.

Frogs mating

Listening to a deafening chorus of Cope's gray treefrogs on a spring evening, scientists have wondered: Do female frogs use a similar strategy to pick important messages about potential mates out of the cacophony? The chorus consists of the calls of countless individual male frogs, each of which is conveying information about which species it is and how fit it is -- with faster, longer calls indicating fitter individuals. To ensure the best survival of their young, "the females have to be able to tell the appropriate species and be able to choose a high-quality male," says Norman Lee, a postdoctoral fellow in the Department of Ecology, Evolution, and Behavior. But how can they, when everyone is talking at the same time?

Working with associate professor Mark Bee and colleagues in EEB and the Department of Psychology, Lee has figured out what traits of the background noise of frog choruses allow females to tune out the hubbub and tune into the hubba-hubba -- with implications not only for our understanding of frog ecology and evolution, but also for our ability to help humans hear.

Lee knew from others' research that humans are able to hear certain sounds better in noisy settings when the background noise is "comodulated" -- meaning that the various frequencies of sound it comprises vary in loudness together. Could the fact that the background noise is comodulated be a key to the frogs' success? To find out, he first built a model of the Cope's gray treefrog's ear and used it to determine how this species may process the background chorus. He then analyzed frog choruses and discovered that the chorus input indeed is comodulated.

Read on 

Fish show cheating can be better than playing by the rules in the mating game

January 30, 2017 by Domino Joyce, The Conversation 

 

The males of some species go to extraordinary lengths to attract females – but some simply cheat. Take African cichlid fish. Many males build underwater "sandcastle" structures that the females use to judge the quality of their potential mates. But, as my colleagues and I found out during a recent study, some males don't bother with this show of construction prowess, and instead are able to father offspring by engaging in "sneaky mating". 

There are hundreds of species of colourful cichlid fish in Lake Malawi, Africa, and about two hundred of these build pit- or volcano-shaped structures known as "bowers" out of sand. Each species builds a slightly different type of sand bower, and they function as a signal of male quality, both to other males, and to females.

The females are what are known as mouthbrooders. After courtship with their male partners, which takes place on top of the bower, the females lay eggs and pick them up in their mouths. The males then fertilise the eggs while they are still in the females' mouths.

The females then carry the eggs for about three weeks until they hatch into baby fish known as "fry". The male contributes no parental care, nothing but his genetic material. So the females need to ensure they choose high quality males, and they use the shape of his bower to do this.

The males even help the females to do this by congregating in breeding arenas called "leks". The females can then visit a lek and judge a large number of males at once, usually laying only a handful of eggs with each chosen male. The ability to build and defend a bower in this hotbed of male activity is thought to demonstrate the quality of the male to the females. It takes two to three weeks for each male to build his bower and he has to work hard to maintain it over a breeding season of several weeks

Read more at:

Spider Shows Off His Big Paddle to Woo Mates

by Tia Ghose, Senior Writer   |   January 22, 2016 09:14am ET

Males of the human variety may spend hours at the gym bulking up to attract the ladies, but that's nothing compared to the efforts of a new spider species from Australia.

This little brown spider sports a massive, paddlelike appendage on its legs that it flashes at females to woo mates, new research has revealed.

The new spider species, Jotus remus, can do this paddle "peekaboo" routine for hours, all to get female spiders to accept its advances. The paddle seems to be a way of separating the fertile females from those that have no interest in mating, said Jürgen Otto, the biologist who discovered the oddball spider. 

Continued …

Female fish that avoid mating with related species also shun some of their own

Date:

March 6, 2015

Source:

University of Illinois at Urbana-Champaign

Summary:

A new study offers insight into a process that could lead one species to diverge into two, researchers report. The study found that female killifish that avoid mating with males of a closely related species also are less likely to mate with males of their own species -- if those males come from an unfamiliar population.

Continued ...

Diving beetle's sticky underwater mating secret

By Victoria Gill

Science reporter, BBC News

Scientists in Taiwan have revealed how a diving beetle hangs on to its mate underwater.

The micro-scale study revealed how bristles on male beetles' legs attach to females with tiny suckers or spatulas.

As well as shedding light on evolution at a minute scale, understanding this could inspire the design of devices for underwater attachment in engineering.

The results are published in the Royal Society journal Interface.

The team, led by Dr Kai-Jung Chi from National Chung Hsing University in Taiwan, directly measured the gripping force of the "attachment devices" on the leg bristles of two diving beetle species.

The efficiency of this underwater attachment, Dr Chi explained, was vital for the survival of the beetle.

"Once mating completes, the male has to separate from the female to get oxygen from the water surface or otherwise it may die," she told BBC News.

Continued and video

Reptile romance a field of conflict – via Herp Digest

Wednesday, 13 November 2013 Dani Cooper

ABC

Mating for one male North American snake is not so much about romancing the reptile but rather a case of hold tight and hang on, a new study reveals.

The study, published today in Proceedings of the Royal Society B, shows the idea that males and females have to co-operate during mating does not apply to some species.

Instead mating can be characterised as a form of sexual conflict, says first author Dr Christopher Friesen, of the University of Sydney's School of Biological Sciences.

His study reveals male and female red-sided garter snakes, Thamnophis sirtalis, have conflicting views about the ideal length of copulation.

Females tend to favour shorter copulations, says Friesen, as it increases their ability to choose other mates to father offspring and reduces the risk of predation.

"For males however, longer copulations can serve not only to transfer more sperm, but also to 'mate-guard' the female," he and his US colleagues write.

This evolutionary conflict has led the snakes to develop gender-specific behaviours and anatomy to help them gain the upper hand during mating, says Friesen.

To test this theory, Friesen and his colleagues manipulated genital traits in wild male and female red-sided garter snakes that were key to their control of copulation.

The team removed a small hook-like spine from the male garter snake's hemipene (snake's penis) that Friesen theorised helped stop the female from evicting him during mating.

In a second experiment, the researchers anaesthetised the females' vaginal pouch to stop them using powerful muscles to terminate copulation.

Friesen says when the male's "hook" was removed, copulation time was significantly shortened and the male's ability to deposit a copulatory plug that stops sperm leakage, among other things, was limited.

The mating was mostly terminated by the female rolling off the male, he says.

Inversely anaethetisation of the females' vaginal pouch increased copulation time as the females' ability to eject the male was reduced.

Natural phenomena

The experiments were conducted as the snakes emerged from winter hibernation in Manitoba, central Canada. The event is a tourist attraction and natural phenomena.

Friesen says some snake dens can contain up to 10,000 snakes in an area the size of a living room with the ratio strongly male biased.

In larger dens between 20 to 50 males can congregate around a newly emerged female, forming 'mating balls' in which they compete to copulate.

He says the females are cold and hungry when they emerge and cannot move quickly. In this environment mating is effectively random and the female is unable to choose larger, fitter males.

Friesen says the results show how sexual conflict plays a role in evolution.

"The evolution of the basal spine (the hook) allows males to gain more control over copulation duration, forcing females to evolve some counter trait to regain some control," he writes.

Friesen says it is in the females' interest to limit copulation duration as a shorter mating time results in a smaller copulatory plug, which also stops the female from mating with another male and acts as a spermatophore from which sperm are released.

These plugs dissolve over a couple of days, so the smaller the plug the shorter the time before the female can mate again, he says.

This becomes important in terms of mate choice, Friesen says, as the female red-garter snake moves away from the den after about three days.

"As the female moves away from the den, the plug from her first mating dissolves and she may mate again in the ... small aspen groves surrounding the den where larger males are more prevalent and successful," he says.