Examining the ways in which animals communicate

Sex in the animal kingdom is serious business as Robin M. Tinghitella, an assistant professor in the Department of Biological Sciences at the University of Denver, presented her research on how animals communicate the urge to reproduce on Nov. 15.

Tinghitella’s presentation also described how animals, specifically crickets and three-spined stickleback fish, communicate with one another within changing environments .

To start, Tinghitella discussed how evolution was initially thought to have been a historical process that takes place over long periods of time.

She then explained that within the last 20 to 30 years, it was discovered that evolution can happen on contemporary time scales, meaning it can happen within a few months or years.

The causes of rapid evolution include invasions of new habitats, the rise and fall of natural enemies, competitors and resources, along with anthropogenic change which results from human actions and pressure.

Tinghitella explained that in her lab the main focus is on how the conditions of rapid evolution can impact the communication between animals in relation to mating calls.

“That means that we studied sexual signals, things like frog calls and bird plumage, that are typically used by males to attack and convince females to mate with them,” Tinghitella said.

Another area Tinghitella’s lab focuses on is sexual selection within the environment. “Almost all organisms now live in environments that are impacted to some degree by humans whether that’s habitat loss and fragmentation, introducing new species, harvesting, pollution or climate change.”

“All of these things have in common is that they change the environment in which males and females are communicating.”

Tinghitella went on to explain that when environments change rapidly, successful mating is affected by the new environmental change and local population extinction. “This is just because not having offspring is the genetic equivalent of death.”

When faced with environmental changes, Tinghitella explained that organisms can leave that area or stay and adapt to the new environment through rapid evolutionary responses.

Tinghitella then discussed how the outcomes of her studies varied from what was originally thought to have happened. “One of the things that I find really intriguing about my treats of choice is the incredible variation that we find not only among populations of species but also within populations of species.”

After discussing rapid evolution, Tinghitella described the organisms her lab studied starting with crickets and their mating call.

Male crickets use calling songs to attack females by using their wings which creates pulses of sounds.

For the last 15 years, Tinghitella has been studying the sexual signaling of a coastal species of crickets in the Kalaupapa National Park in Hawaii. Tinghitella chose this location to see how the environment would affect how the crickets acted since it was a quieter area.

During her work, she looked at a parasitoid fly that is attracted to the sexual signaling of these crickets saying, “When males call to attract females, they also risk attracting this parasitoid fly.”

When the female fly finds the male cricket, they will spray larvae onto the male which will then burrow themselves into the body of the cricket, eventually killing him.

Tinghitella then described an adapted cricket called the silent winged cricket which doesn’t produce any sound, meaning they are protected from the parasitoid fly. It was found that the mutation to these crickets spread throughout the island in fewer than 20 generations.

On her trip, Tinghitella found a colony of crickets in one location on the park to examine. After catching the native crickets thinking they would be silent, Tinghitella realized that those particular crickets made a purring noise.

Tinghitella went on to describe the importance of their findings saying, “Sexual signals are frequently the only or the most divergent trait between closely related species and that strongly implicates sexual selection.”

“When signals change, we can quickly get reproductive isolation if preferences change instead.”

Tinghitella explained that the evolution of a new sexual signal has only been studied once before in jewel wasps.

On the topic of mating, Tinghitella and her team found that female crickets were attracted to the purring crickets over the silent male crickets as she said that it could be possible that in Kalaupapa, the crickets have become adapted to the purring song.

Tinghitella then discussed the three-spined stickleback fish and the experiments her lab conducted to how female sticklebacks pick a mate.

Within their research, Tinghitella and her lab looked into the offspring of three-spined sticklebacks in regards to their parental relationships and whether that affects who they choose to mate with.

Within the experiment, either the mother, father, both or neither were exposed to a predator to see if they shared the information with their offspring and if it changed the mating decisions of their daughters when they grew up.

Once the offspring were fully grown, Tinghitella and her team found that when the parents were exposed to a predator, it affected the daughter’s behavior, preferences and the males they chose to mate with.

Tinghitella first explained that female sticklebacks typically prefer males with a bright red throat with contrasting blue eyes since it usually indicates that the male is in good condition, is parasite resistant, is able to defend the nest and is successful when mating.

The results found that daughters who had one parent exposed to a predator were attracted to male sticklebacks with duller colors while daughters with both parents exposed to predators were typically attracted to the bright red throat and blue eyes that a typical female stickleback would be attracted to.

“One of the things that I find really intriguing about my treats of choice is the incredible variation that we find not only among populations of species, but also within populations of species”

Robin M. Tinghitella, associate professor at the University of Denver

“This leads us to think a lot about this idea that parental effects on mating could facilitate reproduction in changing environments, but we shouldn’t actually assume that parental effects are going to be adapted.”

To end her presentation, Tinghitella emphasized how rapid evolution can give us an idea of how animals can respond to rapidly changing environments while studying, “[The] persistence, formation and collapse of boundaries between species.”