8.17.16

Feral chickens fly the coop

Red Junglefowl are the same species as chickens (Gallus gallus). On Kauai island, they have mated with feral chickens to produce hybrids (photo by Tontantours).

Red Junglefowl are the same species as chickens (Gallus gallus). On Kauai island, they have mated with feral chickens to produce hybrids (photo by Tontantours).

The activities are as follows:

When domesticated animals that humans keep in captivity escape into the wild, we call them feral. You may have seen feral animals, such as pigeons, cats, or dogs, right in your own backyard. But did you know that there are dozens of other feral species all over the world, including goats, parrots, donkeys, wallabies, and chameleons?

Sometimes feral species interbreed with closely related wild relatives to produce hybrid offspring. Feral dogs, for example, occasionally mate with wolves to produce hybrid pups which resemble both their wolf and dog parents. Over many generations, a population made up of these wolf-dog hybrids can evolve to become more wolf-like or more dog-like. Which direction they take will depend on whether dog or wolf traits help the individual survive and reproduce in the wild. In other words, hybrids should evolve traits that are favored by natural selection.

Photograph of a feral hen on Kauai, with her recently hatched chicks (photo by Pamela Willis).

Photograph of a feral hen on Kauai, with her recently hatched chicks (photo by Pamela Willis).

You might be surprised to learn that, like dogs, chickens also have close relatives living in the wild. These birds, called Red Junglefowl, inhabit the jungles of Asia and also many Pacific islands. Eben is a biologist who studies how the island populations of these birds are evolving over time. He has discovered that Red Junglefowl on Kauai Island, which is part of Hawaii, have recently started interbreeding with feral chickens. This interbreeding has produced a hybrid population of birds that are somewhere in between red junglefowl and domestic chickens.

One of the biggest differences between chickens and Red Junglefowl is their breeding behaviors. Red Junglefowl females lay only a handful of eggs each year and only in the spring. Domestic chickens can lay eggs during any season and sometimes up to 300 or more eggs in one year! Eben wanted to know more about the breeding behaviors of Kauai’s feral populations. In many cases, natural selection favors individuals who produce more offspring during their lifetimes. Because domesticated chickens can lay eggs year-round, Eben thought that the feral population would be evolving to be more like domesticated chickens. He predicted that feral hens would breed in all seasons.

To test his hypothesis, Eben’s research group collected hundreds of photographs and videos of Kauai’s hybrid chickens. Tourists delight in photographing Kauai’s wild chickens and uploading their media to the internet. Fortunately for Eben, their cameras and cell phones often record the dates that images are taken. Eben looked at media posted on websites like Flickr and YouTube to find documentation of feral chickens throughout the year. This allowed him to see whether chicks are present during each of the four seasons. He knew that any hen observed with chicks had recently mated and hatched eggs because the chicks only stay with their mothers for only a few weeks.

Featured scientist: Eben Gering from Michigan State University 

Flesch–Kincaid Reading Grade Level = 10.6

To learn more about feral chickens and Eben’s research, check out the popular science articles below:

Mini documentary you can watch in class. The video gives a brief history of chickens on the island of Kauai, and shows mother hens with their chicks:

Cock a Doodle Doo from John Goheen on Vimeo.

Students can watch the same videos that Eben used to collect his experimental data. They can find these videos by searching YouTube for “feral chickens Kauai” and many examples will come up, like this video:

2013-02-25 18.11.57

About Eben: One of the most exciting things I learned as a college student was that natural populations sometimes evolve very quickly. Biologists used to think evolution was too slow to be studied “in action”, so their research focused on evolutionary changes that occurred over thousands (or even millions) of years. I study feral animal populations to learn how rapid evolutionary changes help them survive and reproduce, without direct help from us.

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5.16.16

How the cricket lost its song, Part II

In Part I you determined that the Kauai flatwing mutation led to a decrease in parasitism rates for male crickets. Today, most of the male crickets on Kauai have evolved flat wings and can no longer produce songs that were previously used to attract female crickets. Without their songs, how do males attract females?

Robin collecting data on satellite behavior in normal and flatwing mutation males.

Robin collecting data on satellite behavior in normal and flatwing mutation males.

The activities are as follows:

Without their song, how are flatwing crickets able to attract females? In some other animal species, like birds, males use an alternative to singing, called satellite behavior. Satellite males hang out near a singing male and attempt to mate with females who have been attracted by the song. This helps satellite males in two ways: they don’t use energy to make a song, and they avoid attracting enemies like the fly. Perhaps the satellite behavior gives flatwing males the opportunity to mate with females who were attracted to the few singing males left on Kauai.

Collecting crickets at the speaker.

Collecting crickets at the speaker.

To test this idea, Robin set up a speaker playing cricket songs in the fields where the crickets live on Kauai, Oahu, and the Island of Hawaii. The speaker tricks male and female crickets into thinking there is a male cricket in the area making songs. Before the start of the experiment, Robin removed all the males found within a 2-meter circle around the speaker. She then broadcast cricket songs from the speaker for 20 minutes. She returned and counted the number of males in the 2-meter circle, measured the distance from male to the speaker, and noted whether each male was normal or flatwing. Robin expected that flatwing males would be more likely to use satellite behavior and, therefore, would be on average closer to the speaker than normal males.

Featured scientist: Robin Tinghitella from the University of Denver

Flesch–Kincaid Reading Grade Level = 10.0

Additional teacher resources related to this Data Nugget include:

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6.22.15

How the cricket lost its song, Part I

Screen Shot 2015-06-22 at 12.41.05 PMThe activities are as follows:

Some of the most vibrant and elaborate traits in the animal kingdom are signals used to attract mates. These mating signals include the bright feathers and loud calls of birds or the swimming dances performed by fish. Most of the time the males of the species perform the mating signals, and females use those signals to choose a mate. While mating signals help attract females, they may also attract unwanted attention from other species, like predators.
Screen Shot 2015-06-22 at 12.29.30 PM

Robin is a scientist who studies the mating signals of Pacific field crickets. These crickets live on several of the Hawaiian Islands. Male field crickets make a loud, long-distance song to help females find them and then switch to a quiet courtship song once a female comes in close. Males use specialized structures on the wings to produce songs.

One summer, Robin noticed that the crickets on one of the islands, Kauai, were unusually quiet. Only a couple of years before, Kauai had been a very loud place to work; however, that year Robin heard no males singing! After taking the crickets back to the lab, she noticed that there was something different about the males’ wings on Kauai. Most (95%) of males were missing all of the structures that are used to produce the calling and courtship songs—they had completely lost the ability to produce song! She decided to call this new type of male a flatwing male. But why did these males have flat wings?

Screen Shot 2015-06-22 at 12.29.38 PMOn Kauai, songs of the male crickets attract female crickets, but they are also overheard by a deadly parasitoid fly. The fly sprays its larvae on the backs of the crickets. The larvae then burrow into the crickets’ body cavity and eat them from the inside out! Because flatwing males cannot produce songs, flat wings may help male crickets remain unnoticed by the parasitoid flies. To test this idea, Robin dissected the males to look for fly larvae. She compared infection levels for 67 normal males—collected before the flatwing mutation appeared in the population—to 122 flatwing males that she collected after the flatwing mutation appeared. She expected fewer males to be infected by the parasitoid fly after the appearance of the flatwing mutation in the cricket population.

Featured scientist: Robin Tinghitella from the University of Denver

Flesch–Kincaid Reading Grade Level = 9.1

Additional teacher resources related to this Data Nugget include:

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9.25.14

Sexy smells

Danielle holding a male junco. Notice the white tail feathers.

Danielle holding a male junco. Notice the white tail feathers.

The activities are as follows:

Animals collect information about each other and the rest of the world using multiple senses, including sight, sound, and smell. They use this information to decide what to eat, where to live, and who to pick as a mate. Choosing a mate is an important decision that requires a lot of information, such as how healthy a potential partner is, and information about their genes. Mate quality can affect how many offspring an animal has and if their genes will get passed on to the next generation.

Danielle removing preen oil from a junco.

Danielle removing preen oil from a junco.

Many male birds have brightly colored feathers that are attractive to females. For example, the peacock has bright and elaborate tail feathers that are thought to communicate a male’s quality to the females. Besides using their sense of sight to see feathers, female birds may use their other senses to gather information about potential mates as well. Danielle is a biologist and she wanted to figure out if birds use vision and their other senses, such as smell, to determine the quality of potential mates.

Danielle decided to research how dark-eyed juncos communicate through their sense of sight and smell. Dark-eyed juncos are a type of sparrow. They are not colorful birds like peacocks, but they do have bright white feathers in their tails. Male dark-eyed juncos have more tail-white than females. Danielle thought is possible that females use the amount of white in a male’s tail to determine whether he is a high quality mate. Danielle was also interested in several chemical compounds found in junco preen oil, which birds spread on their feathers. This preen oil contains compounds that give birds their odor. Danielle found that males and females have different odors! Just as males have more white in their tail feathers, they also produce more of a chemical called 2-pentadecanone. Danielle wanted to test whether this chemical functioned as a signal to females of mate quality.

A preen gland where birds produce preen oil.

A preen gland where birds produce preen oil.

To test her two potential hypotheses, Danielle captured male juncos at Mountain Lake Biological Station in Virginia. She measured the amount of tail-white by estimating the proportion of each tail feather that was white, and adding up the values from each feather. She also took preen oil samples and measured the percent of each sample that was made up of 2-pentadecanone. She followed these birds for one breeding season to find out how many offspring they had. If females pick mates based on visual ornaments, then she predicted males with more tail-white would have more offspring. If females pick mates based on smell, then she predicted males with more 2-pentadecanone would have more offspring.

Featured scientist: Danielle Whittaker from Michigan State University

Flesch–Kincaid Reading Grade Level = 9.4

Additional classroom resources for this Data Nugget:

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6.6.14

Fish fights

A male in his territory (front) and an intruding male (back)

A male in his territory (front) and an intruding male (back)

The activities are as follows:

In many animals, males fight for territories. Getting a good territory and making sure other males don’t steal it is very important! Males use these territories to attract females for mating. The males that get the best territories are more likely to mate with females and have more babies. Only the males that have babies will pass on their genes to the next generation.

Stickleback fish use the shallow bottom areas of lakes to mate. Male stickleback fish fight each other to gain the best territories in this habitat. In their territories, males build a nest out of sand, aquatic plants, and glue they produce from their kidneys. The better the nest, the more females a male can attract. Males then use courtship dances to attract females to their nests. If a female likes a male, she will deposit her eggs in his nest. Then the male will care for those eggs and protect the offspring that hatch.

Scientist Alycia out in the field collecting male stickleback fish for her experiments

Scientist Alycia out in the field collecting male stickleback fish for her experiments

Alycia is a scientist who is interested in understanding what makes a male stickleback a good fighter and defender of his territory. Perhaps more aggressive males are better at defending their territory and nests because they are better at fighting off other males. She used sticklebacks she collected from British Columbia to test her hypothesis.

In her experiment, 24 males were kept in 6 large tanks, with 4 males in each tank. Alycia watched each of the 24 males every day for 10 days. She recorded the behaviors of each fish when they were competing for territories, defending their territory, and building their nests. She also recorded the size of the males’ territories and whether they had a nest each day.

Featured scientist: Alycia R. Lackey from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.7

More news on Alycia’s work on stickleback fish can be found at her BEACON blog post, “Making and Breaking a Species.” 

A male (right) defending his territory from another fish (left).

A male (right) defending his territory from another fish (left).

6.6.14

Which guy should she choose?

sticklebackmale

A male stickleback tending his nest. Notice the male’s bright red throat, blue eye, and blue-green body.

The activities are as follows:

In many animals, males use complex behaviors to attract females. They use displays to show off colorful parts of their bodies, like feathers or scales. For example, male peacocks fan out and shake their colorful tails to attract female attention. These displays take up a lot of energy, and yet some males are unable to attract any females while other males attract many females.

In stickleback fish, males are very colorful to attract females. Their throats turn bright red during the spring when they mate. Stickleback males also court females with zig-zag swimming! The males swim in a z-shaped pattern in front of the female, probably to show off their mating colors. Before male fish can get the attention of female fish, they must gain a territory and build a nest. In sticklebacks, females inspect nests that the males build and then decide if they want to deposit their eggs. Males care for the offspring before and after the eggs hatch. A female fish would benefit from identifying “high quality” males and choosing those males for mates. High quality males would have more energy to protect their offspring and would make better fathers. They could also pass on genes that make offspring more attractive to females in the next generation.

Scientist Alycia collecting fish from a freshwater lake in British Columbia, Canada.

Scientist Alycia collecting fish from a freshwater lake in British Columbia, Canada.

Alycia is a scientist who is interested in the stickleback’s mating behaviors. She wanted to figure out why there are differences between males and why certain males can attract a mate while others cannot. What is it about the way a male looks, moves, or smells that attracts females? What male traits are females looking at when deciding on a mate? Alycia thought female sticklebacks may choose males with redder throats and/or more complex behaviors because those traits show the female that those males are high quality. Previous work with these fish showed that male behavior, color, or territory size, or the presence of a nest could all be important. But it was still not clear which characteristic might be most important.

Alycia set up an experiment to figure out if male throat color or zig-zag swimming behaviors were attractive to females. She used a total of 24 male fish and six 75-gallon tanks. She divided the males up evenly between the large tanks, placing four males in each one. For 10 days she observed the male fish and recorded competition behaviors, territory defense, and nest building. On the tenth day, she introduced one female to each tank of four males. She recorded how the males behaved in courtship and which males the females chose. She also recorded the redness of each male.

Featured scientist: Alycia R. Lackey from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.9

More news on Alycia’s work on stickleback fish can be found at her BEACON blog post, “Making and Breaking a Species” and her blog post for the MSU museum. 

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