ecology ‣ Data Nuggets

5.11.18

Bringing back the Trumpeter Swan

Joe with a Trumpeter Swan.

The activities are as follows:

The Kellogg Bird Sanctuary was created in 1927 to provide safe nesting areas for waterfowl such as ducks, geese, and swans. During that time many waterfowl species were in trouble due to overhunting and the loss of wetland habitats. One species whose populations had declined a lot was the Trumpeter Swan. Trumpeter swans are the biggest native waterfowl species in North America. At one time they were found across North America, but by 1935 there were only 69 known individuals in the continental U.S.! The swans were no longer found in Michigan.

The reintroduction, or release of a species into an area where they no longer occur, is an important tool in helping them recover. In the 1980s, many biologists came together to create a Trumpeter Swan reintroduction plan. Trumpeter Swans in North America can be broken up into three populations – Pacific Coast, Rocky Mountain, and Interior. The Interior is further broken down into Mississippi/Atlantic and High Plains subpopulations. Joe, the Kellogg Bird Sanctuary manager and chief biologist, wrote and carried out a reintroduction plan for Michigan. Michigan is part of the Mississippi/Atlantic subpopulation. Joe and a team of biologists flew to Alaska in 1989 to collect swan eggs to be reared at the sanctuary. After two years the swans were released throughout Michigan.

The North American Trumpeter Swan survey has been conducted approximately every 5 years since 1968 as a way to estimate the number of swans throughout their breeding range. The survey is conducted in late summer when young swans can’t yet fly but are large enough to count. Although the surveys are conducted across North America, the data provided focuses on just the Interior Population, which includes swans in the High Plains and Mississippi/Atlantic Flyways.

Featured scientist: Wilbur C. “Joe” Johnson from the W.K. Kellogg Bird Sanctuary. Written by: Lisa Vormwald and Susan Magnoli from Michigan State University.

Flesch–Kincaid Reading Grade Level = 11.5

Additional teacher resource related to this Data Nugget:

The 2015 North American Trumpeter Swan Survey
Current conservation efforts in North America – The Trumpeter Swan Society
The comeback story of Michigan’s native Trumpeter Swans – Michigan Radio
Learn more about trumpeter Swan natural history here and here.
A New York Times article from 1987 on Trumpeter Swan reintroduction in Michigan
Article from The Outdoor Journal on Trumpeter Swan recovery in Michigan
Use eBird, a database of citizen science bird sightings, to look for Trumpeters near you
Learn more about the Kellogg Bird Sanctuary

A video on Trumpeter Swan reintroduction efforts that could be shown before the Data Nugget to engage students with the topic, or after to expand the research beyond the one study:

SaveSave

4.16.18

The case of the collapsing soil

An area in the Florida Everglades where strange soil collapse has been observed.

The activities are as follows:

As winds blow through the large expanses of grass in the Florida Everglades, it looks like flowing water. This “river of grass” is home to a wide diversity of plants and animals, including both the American Alligator and the American Crocodile. The Everglades ecosystem is the largest sub-tropical wetland in North America. One third of Floridians rely on the Everglades for water. Unfortunately, this iconic wetland is threatened by rising sea levels caused by climate change. Sea level rise is caused by higher global temperatures leading to thermal expansion of water, land-ice melt, and changes in ocean currents.

With rising seas, one important feature of the Florida Everglades may change. There are currently large amounts of carbon stored in the wetland’s muddy soils. By holding carbon in the mud, coastal wetlands are able to help in the fight against climate change. However, under stressful conditions like being submersed in sea water, soil microbes increase respiration. During respiration, carbon stored in the soil is released as carbon dioxide (CO₂), a greenhouse gas. As sea level rises, soil microbes are predicted to release stored carbon and contribute to the greenhouse effect, making climate change worse.

Shelby collecting soil samples from areas where the soil has collapsed in the Everglades.

Shelby and John are ecologists who work in southern Florida. John became fascinated with the Everglades during his first visit 10 years ago and has been studying this unique ecosystem ever since. Shelby is interested in learning how climate change will affect the environment, and the Everglades is a great place to start! They are both very concerned with protecting the Everglades and other wetlands. Recently when John, Shelby, and their fellow scientists were out working in the Everglades they noticed something very strange. It looked like areas of the wetland were collapsing! What could be the cause of this strange event?

John and Shelby thought it might have something to do loss of carbon due to sea level rise. They wanted to test whether the collapsing soils were the result of increased microbial respiration, leading to loss of carbon from the soil, due to stressful conditions from sea level rise. They set out to test two particular aspects of sea water that might be stressful to microbes – salt and phosphorus.

Phosphorus is found in sea water and is a nutrient essential for life. However, too much phosphorus can lead to over enriched soils and change the way that microbes use carbon. Sea water also contains salt, which can stress soil microbes and kill plants when there is too much. Previous research has shown that both salt and phosphorus exposure on their own increase respiration rates of soil microbes.

A photo of the experimental setup. Each container has a different level of salt and phosphorus concentration.

To test their hypotheses, a team of ecologists in John’s lab developed an experiment using soils from the Everglades. They collected soil from areas where the soil had collapsed and brought it into the lab. These soils had the microbes from the Everglades in them. Once in the lab, they put their soil and microbes into small vials and exposed them to 5 different concentrations of salt, and 5 different concentrations of phosphorus. The experiment crossed each level of the two treatments. This means they had soil in every possible combination of treatments – some with high salt and low phosphorus, some in low salt and high phosphorus, and so on. Their experiment ran for 5 weeks. At the end of the 5 weeks they measured the amount of CO₂released from the soils.

Featured scientists: John Kominoski and Shelby Servais from Florida International University. Written by Shelby, John, and Teresa Casal.

Flesch–Kincaid Reading Grade Level = 9.2

SaveSave

12.8.17

Which would a woodlouse prefer?

Woodlice are small crustaceans that live on land. They look like bugs, but are actually more closely related to crabs and lobsters! Photo credit Liz Henwood.

The activities are as follows:

Woodlice are small crustaceans that live on land. They look like bugs, but are actually more closely related to crabs and lobsters. To escape predators they hide in dark places. They spend most of their time underground and have very poor eyesight.

One day, when digging around in the dark dirt of her compost pile, Nora noticed that there were many, many woodlice hiding together. This made her wonder how woodlice decide where to live. Because woodlice have very simple eyesight, Nora thought that maybe they use dark and light colors to decide where to go. They might choose to move towards darker colors and away from lighter colors to prevent ending up above ground where predators can easily find them.

Nora collecting woodlice from the compost pile.

Nora, along with classmates in her ecology class at Michigan State University, decided to run an experiment to study woodlice behavior. She collected 10 woodlice from her compost pile and placed them in a jar. She brought the jar into the lab. Then she chose a set of trays to work with from what she had in the lab – white, with tall sides. The sides of the tray were tall and smooth so the woodlice were not able to climb out. On one end of the tray Nora put some dark soil, and on the other side she put lighter leaves. If her hypothesis was correct, Nora predicted that woodlice would more often choose to move towards the dark soil habitat, compared to the lighter leaves habitat.

For each trial, Nora gently picked up a single woodlouse with forceps. She then placed it in the center of the tray. All the woodlice were positioned so they started facing the top of the tray, not at either habitat type. The woodlice then chose to move towards one end of the tray or the other. When they reached one of the piles the students recorded which habitat they chose. It was then picked up with forceps. Nora and her classmates recorded its length and placed it in a new jar so it could be released back into the compost pile once the experiment was done.

The tray where the preference trials were conducted. To the right of the tray is the soil pile, and to the left is the leaf pile. The center was purposefully left empty and wiped down before each run.

After running this experiment and looking at the data, Nora realized it did not work. The small sample size of only 10 individuals was not enough to see a pattern. Also, she realized that after one woodlouse went a certain way, all the others would follow it, maybe because they were following a scent trail. She decided she had to do the experiment again, this time with more woodlice and in a way that would prevent them following each other’s scent trails.

For her second try, Nora collected 51 woodlice from a different compost pile. Just like the first experiment, Nora placed lighter leaves on one end of a white tray and dark soil on the other. All the methods were the same, except for a few important changes. To get rid of scent trails, this time Nora wiped down the middle of the tray with a clean wet paper towel between trials. She also added equal amounts of water to both habitats to control for humidity. This ensured that if woodlice did show a preference for either habitat it would be due to habitat color, not humidity. This time Nora used a stopwatch and recorded how long it took for an individual to choose one of the two habitats.

Featured scientist: Nora Straquadine from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.7

Additional teacher resource related to this Data Nugget:

PowerPoint slideshow of images of woodlice and Nora’s experiment.
A great video to show before the Data Nugget to engage students with the activity – gives background on woodlice and describes the role that water plays for these crustaceans that live on land:

A video of woodlice on a fallen tree. This video has no audio, but can be useful for students to observe woodlice behavior:

About Nora: Nora is currently an undergraduate getting her B.S. in Zoology with a concentration in Zoo and Aquarium as well as a minor in Marine Ecosystem Management from Michigan State University. Although aquatic life is her main interest, she think it’s important to appreciate other animal groups and take a break to play and explore the nature around you. That curiosity was how she was able to volunteer in labs on campus from entomology to genetics, and how she came to spend a summer at the Kellogg Biological Station in Michigan.

SaveSave

6.27.17

City parks: wildlife islands in a sea of cement

Image of a red fox caught on one of the wildlife cameras.

The activities are as follows:

For most of our existence, humans have lived in rural, natural places. However, more and more people continue to move into cities and urban areas. The year 2008 marked the first time ever in human history that the majority of people on the planet lived in cities. The movement of humans from rural areas to cities has two important effects. First, the demand that people place on the environment is becoming very intense in certain spots. Second, for many people, the city is becoming the main place where they experience nature and interact with wildlife on a regular basis.

Remington and Grant are city-dwellers and have been their entire lives. Remington grew up in Tulsa, Oklahoma and Grant is from Cleveland, Ohio. In Tulsa, Remington fell in love with nature while running on the trails of city parks during cross country and track practices. Grant developed a love for nature while fishing and hiking in the Cleveland Metroparks in Ohio. These experiences led them to study wildlife found in urban environments because they believe that cities can be places where both humans and wildlife thrive. However, to make this belief a reality, scientists must understand how wildlife are using habitats within a city. This knowledge will provide land managers the information they need to create park systems that support all types of species. However, almost all research done on wildlife takes place in natural areas, like national parks, so there is currently very little known about wildlife habits in urban areas. To address this gap in knowledge, Remington, Grant, and their colleagues conduct ecological research on the urban wildlife populations in the Cleveland Metroparks.

Remington prepares to attach the camera to a buckeye tree. He secures them with a heavy-duty lock to keep the cameras safe from theft by people using the parks.

The Cleveland Metroparks are a collection of wooded areas that range in size, usage, and maintenance. Some are highly used small parks with mowed grass, while others are large, rural parks with thousands of acres of forest and miles of winding trails. As they began studying the Metroparks, they noticed the parks were like little “islands” of wildlife habitat within a large “sea” of buildings, pavement, houses and people. This reminded Remington and Grant of a fundamental theory in ecology: the theory of island biogeography. This theory has two components: size and isolation of islands. The first predicts that larger islands will have higher biodiversity because there are more resources and space to support more wildlife than smaller areas. The second is that islands farther away from the mainland will have lower biodiversity because more isolated islands are harder for wildlife to reach. Remington and Grant wondered if they could address this first component in the wide variety of areas that are part of the Cleveland Metroparks. If the theory holds for the Metroparks, it could help them to figure out where most species live in the park system and help managers better maximize biodiversity. It would also provide an important link between ecological research conducted in natural areas and urban ecology.

To evaluate whether the theory of island biogeography holds true in urban areas, Remington and Grant set up 104 wildlife cameras throughout the parks. These cameras photograph animals when triggered by motion. They used these photographs to identify the locations of wildlife in the parks and to get a count of how many individuals there are, known as their abundance. With these data, they tested whether the size of the park would influence biodiversity as predicted by the theory of island biogeography.

One challenge with measuring “biodiversity” is that it means different things to different people. Remington and Grant looked at two common measurements of biodiversity. First, species richness, which is the number of different species observed in each park. Second, they calculated the Shannon Wiener Index of biodiversity for each park. This index incorporates both species richness and species evenness. Species evenness tells us whether the abundances of each species are similar, or if one type is most common and the others are rare. Evenness is important because it tells you whether a park has lots of animals from many different species or if most animals are from a single species. If a park has greater evenness of species, the Shannon-Wiener index will be higher.

Featured scientists: Remington Moll and Grant Woodard from Michigan State University

Flesch–Kincaid Reading Grade Level = 11.4

Additional teacher resource related to this Data Nugget:

Remington and Grant have made their data available for use in classrooms. If you would like to have your students work with raw data, it can be used to calculate the Shannon Wiener Index, or explore other aspects of species richness and evenness in the parks. This data is not yet published, so keep in mind this data is intended only for classroom use. Download the Excel file here!
PowerPoint slideshow of images from the wildlife cameras in the Cleveland Metroparks.
Citizen science Zooniverse site where students can view data and identify species from Remington and Grant’s cameras.
For more background on the importance of biodiversity, students can eat this article in The Guardian – What is biodiversity and why does it matter to us?

SaveSave

About Remington: Remington is a Ph.D. student and NSF Graduate Research Fellow at Michigan State University in Dr. Bob Montgomery’s lab. Prior to Michigan State, Remington received B.S. and M.S. degrees from the University of Missouri, where he worked with Dr. Josh Millspaugh. Following his M.S., he spent time in Amman, Jordan doing work with the Royal Society for the Conservation of Nature and spent three years teaching high school biology, chemistry, and theology at the Beirut Baptist School in Lebanon.

He uses cutting-edge technologies such as GPS collars and camera-traps to study predator-prey interactions between large carnivores and their prey. He is particularly excited about evaluating how ecological theory developed in “natural” areas like national parks applies to urban contexts. Remington grew up in the city and fell in love with nature and ecology in city parks. Although it carries substantial challenges, Remington believes that humans and large predators can peaceably coexist, even in and around cities. It is his goal to use the lessons learned in his research to help make that belief a reality.

SaveSave

5.1.17

Marsh makeover

A saltmarsh near Boston, MA being restored after it was degraded by human activity.

The activities are as follows:

Salt marshes are diverse and productive ecosystems, and are found where the land meets the sea. They contain very unique plant species that are able to tolerate flooding during high tide and greater salt levels found in seawater. Healthy salt marshes are filled with many species of native grasses. These grasses provide food and nesting grounds for lots of important animals. They also help remove pollution from the land before it reaches the sea. The grass roots protect the shoreline from erosion during powerful storms. Sadly today, humans have disturbed most of the salt marshes around the world. As salt marshes are disturbed, native plant biodiversity, and the services that marshes provide to us, are lost.

A very important role of salt marshes is that they are able to store carbon, and the amount they store is called their carbon storage capacity. Carbon is stored in marshes in the form of both dead and living plant tissue, called biomass. Marsh grasses photosynthesize, taking carbon dioxide out of the atmosphere and storing it in plant biomass. This biomass then falls into the mud and the carbon is stored there for a very long time. Salt marshes have waterlogged muddy soils that are low in oxygen. Because of the lack of oxygen, decomposition of dead plant tissue is much slower than it is in land habitats where oxygen is plentiful. All of this stored carbon can help lower the levels of carbon dioxide in our atmosphere. This means that healthy and diverse salt marshes are very important to help fight climate change.

However, as humans change the health of salt marshes, we may also change the amount of carbon being stored. As humans disturb marshes, they may lower the biodiversity and fewer plant species can grow in the area. The less plant species growing in the marsh, the less biomass there will be. Without biomass falling into the mud and getting trapped where there is little oxygen, the carbon storage capacity of disturbed marshes may go down.

Jennifer, working alongside students, to collect biomass data for a restored saltmarsh.

It is because of the important role that marshes play in climate change that Jennifer, and her students, spend a lot of time getting muddy in saltmarshes. Jennifer wants to know more about the carbon storage capacity of healthy marshes, and also those that have been disturbed by human activity. She also wants to know whether it is possible to restore degraded salt marshes to help improve their carbon storage capacity. Much of her work focuses on comparing how degraded and newly restored marshes to healthy marshes. By looking at the differences and similarities, she can document the ways that restoration can help increase carbon storage. Since Jennifer and her students work in urban areas with a lot of development along the coast, there are lots of degraded marshes that can be restored. If she can show how important restoring marshes is for increasing plant diversity and helping to combat climate change, then hopefully people in the area will spend more money and effort on marsh restoration.

Jennifer predicted that: 1) healthy marshes will have a higher diversity of native vegetation and greater biomass than degraded salt marshes, 2) restored marshes will have a lower or intermediate level of biomass depending on how long it has been since the marsh was restored, and 3) newly restored marshes will have lower biomass, while marshes that were restored further in the past will have higher biomass.

To test her predictions, Jennifer studied two different salt marshes near Boston, Massachusetts, called Oak Island and Neponset. Within each marsh she sampled several sites that had different restoration histories. She also included some degraded sites that had never been restored for a comparison. Jen measured the total number of different plant species and plant biomass at multiple locations across all study sites. These measurements would give Jen an idea of how much carbon was being stored at each of the sites.

Featured scientist: Jennifer Bowen from Northeastern University

Flesch–Kincaid Reading Grade Level = 11.0

11.17.16

When a species can’t stand the heat

An adult male tuatara. Photo by Scott Jarvie.

The activities are as follows:

Tuatara are a unique species of reptile found only in New Zealand. Tuatara look like lizards but they are actually in their own reptile group. Tuatara are the only species remaining on the planet from this lineage, one that dates to the time of the dinosaurs! Tuatara are similar to tortoises in that they are extremely long-lived and can sometimes live over 100 years. Tuatara start reproducing when they are about 15–20 years old and they breed infrequently.

North Brother Island, one of the small New Zealand islands where tuatara are still found today. Photo by Jo Monks.

The sex of tuatara is not determined by sex chromosomes (X or Y) as in humans. Instead, the temperature of the nest during egg development is the only factor that determines the sex of tuatara embryos. If the egg develops with a low temperature in the nest it will be female, but if it develops with a high temperature it will be male. This process happens in many other species, too, including some turtles, crocodiles, lizards, and fish. However, most species are the opposite of tuatara and produce females at the warmest temperatures.

Today, tuatara face many challenges. Humans introduced new predators to the large North and South Islands of New Zealand. Tuatara used to live on these main islands, but predators drove the island populations to extinction. Today, the tuatara survive only on smaller offshore islands where they can escape predation. Because many of these islands are small, tuatara can have low population numbers that are very vulnerable to a variety of risk factors. One of the current challenges faced by these populations is climate change. Similar to the rest of the world, New Zealand is experiencing higher and higher temperatures as a result of climate change, and the warm temperatures may impact tuatara reproduction.

Kristine collecting data on a tuatara in the field. Photo by Sue Keall.

North Brother Island has a small population of tuatara (350–500 individuals) that has been studied for decades. Every single tuatara has been marked with a microchip (like the ones used on pet dogs and cats), which allows scientists to identify and measure the same individuals repeatedly across several years. In the 1990s, a group of scientists studying the tuatara on this island noticed that there were more males than females (60% males). The scientists started collecting data on the number of males and females so they could track whether the sex ratio, or the ratio of males and females in the population, became more balanced or became even more male-biased over time. The sex ratio is important because when there are fewer females in a population, there are fewer individuals that lay eggs and produce future offspring. Generally, a population that is highly male-biased will have lower reproduction rates than a population that is more balanced or is female-biased.

The fact that tuatara are long-lived and breed infrequently meant that the scientists needed to follow the sex ratio for many years to be sure they were capturing a true shift in the sexes over time, not just a short-term variation. In 2012, Kristine and her colleagues decided to use these long-term data to see if the increasing temperatures from climate change were associated with the changing sex ratio. They predicted that there would be a greater proportion of males in the population over time. This would be reflected in an unbalanced sex ratio that is moving further and further away from 50% males and 50% females and toward a male-biased population.

Featured scientists: Kristine Grayson from University of Richmond, Nicola Mitchell from University of Western Australia, and Nicola Nelson from Victoria University of Wellington

Flesch–Kincaid Reading Grade Level = 11.9

Additional teacher resources related to this Data Nugget:

Video Recording from Headwaters Institute: Lunch with a scientist – Meet Dr. Kristine Grayson!
Want to learn more about tuatara or introduce students to this species before beginning the Data Nugget? Check out this video by “It’s ok to be smart”.
There are two publications associated with the research in this activity:
- Grayson, Kristine L., Nicola J. Mitchell, Joanne M. Monks, Susan N. Keall, Joanna N. Wilson, and Nicola J. Nelson (2014). Sex Ratio Bias and Extinction Risk in an Isolated Population of Tuatara (Sphenodon punctatus). PLoS ONE 9(4): e94214.
- Grayson, Kristine L., Nicola J. Mitchell, and Nicola J. Nelson (2014). A Threat to New Zealand’s Tuatara Heats Up. American Scientist 102: 350-357.
For a popular science article about tuatara research, written for students, check out Science News for Student’s article “When a species can’t stand the heat: Global warming could leave New Zealand’s tuatara dangerously short of females” (PDF for printing, Word Search!)
Students can access the National Institute of Water and Atmospheric Research (NIWA) New Zealand weather station data here.

About Kristine: Kristine L. Grayson is an Associate Professor in the Biology Department at University of Richmond, where she teaches Intro Ecology/Evolution, Field Ecology, Ecophysiology, and Data Visualization. She is an HHMI BioInteractive Ambassador and facilitator with the Quantitative Undergraduate Biology Education and Synthesis (QUBES) project, where you can find additional teaching resources she has authored. Kristine runs an undergraduate research lab studying invasive insects, salamanders, and aquatic macroinvertebrates. Her work on tuatara was conducted during a postdoc at Victoria University of Wellington funded by an NSF International Research Fellowship. One of her claims to fame is capturing the state record holding snapping turtle for North Carolina – 52 pounds! To read more about Kristine and her interest in science from a young age, check out this article.

SaveSave

10.13.16

Winter is coming! Can you handle the freeze?

Doug, and two members of his team, setting up the reciprocal transplant experiment in Scandinavia.

Doug with the reciprocal transplant experiment in Scandinavia.

The activities are as follows:

Doug is a biologist who studies plants from around the world. He often jokes that he chose to work with plants because he likes to take it easy. While animals rarely stay in the same place and are hard to catch, plants stay put and are always growing exactly where you planted them! Using plants allows Doug to do some pretty cool and challenging experiments. Doug and his research team carry out experiments with the plant species Mouse-ear Cress, or Arabidopsis thaliana. They like this species because it is easy to grow in both the lab and field. Arabidopsis is very small and lives for just one year. It grows across most of the globe across a wide range of latitudes and climates. Arabidopsis is also able to pollinate itself and produce many seeds, making it possible for researchers to grow many individuals to use in their experiments.

Doug, and two members of his team, setting up the reciprocal transplant experiment in Scandinavia.

Part I: Doug wanted to study how Arabidopsis is able to survive in such a range of climates. Depending on where they live, each population faces its own challenges. For example, there are some populations of this species growing in very cold habitats, and some populations growing in very warm habitats. He thought that each of these populations would adapt to their local environments. An Arabidopsis population growing in cold temperatures for many generations may evolve traits that increase survival and reproduction in cold temperatures. However, a population that lives in warm temperatures would not normally be exposed to cold temperatures, so the plants from that population would not be able to adapt to cold temperatures. The idea that populations of the same species have evolved as a result of certain aspects of their environment is called local adaptation.

To test whether Arabidopsis is locally adapted to its environment, Doug established a reciprocal transplant experiment. In this type of experiment, scientists collect seeds from plants in two different locations and then plant them back into the same location (home) and the other location (away). For example, seeds from population A would be planted back into location A (home), but also planted into location B (away). Seeds from population B would be planted back into location B (home), but also planted at location A (away). If populations A and B are locally adapted, this means that A will survive better than B in location A, and B will survive better than A in location B. Because each population would be adapted to the conditions from their original location, they would outperform the plants from away when they are at home (“home team advantage”).

In this experiment, Doug collected many seeds from warm Mediterranean locations at low latitudes, and cold Scandinavian locations at high latitudes. He used these seeds to grow thousands of seedlings. Once these young plants were big enough, they were planted into a reciprocal transplant experiment. Seedlings from the Mediterranean location were planted alongside Scandinavian seedlings in a field plot in Scandinavia. Similarly, seedlings from the Scandinavian locations were planted alongside Mediterranean seedlings in a field plot in the Mediterranean. By planting both Mediterranean and Scandinavian seedlings in each field plot, Doug can compare the relative survival of each population in each location. Doug made two local adaptation predictions:

Scandinavian seedlings would survive better than Mediterranean seedlings at the Scandinavian field plot.
Mediterranean seedlings would survive better than Scandinavian seedlings planted at the Mediterranean field plot.

Doug’s team in the Mediterranean prepped and ready to set up the experiment.

Part II: The data from Doug’s reciprocal transplant experiment show that the Arabidopsis populations are locally adapted to their home locations. Now that Doug confirmed that populations were locally adapted, he wanted to know how it happened. What is different about the two habitats? What traits of Arabidopsis are different between these two populations? Doug now wanted to figure out the mechanism causing the patterns he observed.

Doug originally chose Arabidopsis populations in Scandinavia and the Mediterranean for his research on local adaptation because those two locations have very different climates. The populations may have adapted to have the highest survival and reproduction based on the climate of their home location. To deal with sudden freezes and cold winters in Scandinavia, plants may have adaptations to help them cope. Some plants are able to protect themselves from freezing temperatures by producing chemicals that act like antifreeze. These chemicals accumulate in their tissues to keep the water from turning into ice and forming crystals. Doug thought that the Scandinavian population might have evolved traits that would allow the plants to survive the colder conditions. However, the plants from the Mediterranean aren’t normally exposed to cold temperatures, so they wouldn’t have necessarily evolved freeze tolerance traits.

To see whether freeze tolerance was driving local adaptation, he set up an experiment to identify which plants survived after freezing. Doug again collected seeds from several different populations across Scandinavia and across the Mediterranean. He chose locations that had different latitudes because latitude affects how cold an area gets over the year. High latitudes (closer to the poles) are generally colder and low latitudes (closer to the equator) are generally warmer. Doug grew more seedlings for this experiment, and then, when they were a few days old, he put them in a freezer. Doug counted how many seedlings froze to death, and how many survived, and he used these numbers to calculate the percent survival for each population. To gain confidence in his results, he did this experiment with three replicate genotypes per population.

Doug predicted that if freeze tolerance was a trait driving local adaptation, the seedlings originally from colder latitudes (Scandinavia) would have increased survival after the freeze. Seedlings originally from lower latitudes would have decreased survival after the freeze because the populations would not have evolved tolerance to such cold temperatures.

Featured scientist: Doug Schemske from Michigan State University (MSU). Written by Christopher Oakley from MSU and Purdue University, and Marty Buehler (RET) from Hastings High School.

Flesch–Kincaid Reading Grade Level = 12.0

There is one scientific paper associated with the data in this Data Nugget. The citation and PDF of the paper is below.

Agren, J. and D.W. Schemske (2012). Reciprocal transplants demonstrate strong adaptive differentiation of the model organism Arabidopsis thaliana in its native range. New Phytologist 194:1112–1122.

10.5.16

Raising Nemo: Parental care in the clown anemonefish

Clown anemonefish caring for their eggs.

The activities are as follows:

When animals are born, some offspring are able to survive on their own, while others rely on parental care. Parental care can take many forms. One or both parents might help raise the young, or in some species other members of the group help them out. The more time and energy the parents invest, the more likely it is that their offspring will survive. However, parental care is costly for the parents. When a parent invests time, energy, and resources in their young, they are unable to invest as much in other activities, like finding food for themselves. This results in a tradeoff, or a situation where there are costs and benefits to the decisions that must be made. Parents must balance their time between caring for their offspring and other activities.

The severity of the tradeoff between parental care and other activities may depend on environmental conditions. For example, if there is a lot of food available, parents may spend more time tending to their young because finding food for themselves takes less time and energy. Scientists wonder if parents are able to adjust their parental care strategies in response to environmental changes.

Photo of Tina (left) with other members of her lab. The glowing blue tanks around them all contain anemonefish!

Tina is a scientist studying the clown anemonefish. She is interested in how parental care in this species changes in response to the environment. She chose to study anemonefish because they use an interesting system to take care of their young, and because the environment is always changing in the coral reefs where they live.

Anemonefish form monogamous pairs and live in groups of up to six individuals. The largest female is in charge of the group. Only the largest male and female get to mate and take care of the young. Both parents care for eggs by tending them, mouthing the eggs to clean the nest and remove dead eggs, and fanning eggs with their fins to oxygenate them. A single pair may breed together tens or even hundreds of times over their lifetimes. But here is the cool part – anemonefish can change their sex! If the largest female dies, the largest male changes to female, and the next largest fish in line becomes the new breeding male. That means that a single parent may have the opportunity to be a mother and a father during its lifetime.

Parents will fan the eggs to increase oxygen by the nest, or mouth them to remove dead eggs and clean the nest.

On the reef, anemonefish groups also experience shifts in how much food is available. In years with lots of food, the breeding pair has lots of young, and in years with little food they do not breed as often. Tina presumed that food availability determines how much time and energy the parents invest in parental care behaviors. She collected data from 20 breeding pairs of fish, 10 of which she gave half rations of food, and 10 of which she gave full rations. The experiment ran for six lunar months. Every time a pair laid a clutch of eggs, Tina waited 7 days and then took a 15-minute video of the parents and their nest. She watched the videos and measured three parental care behaviors: mouthing, fanning, and total time spent tending for both males and females. Some pairs laid eggs more than once, so she averaged these behaviors across the six months of the experiment. Tina predicted that parents fed a full ration would perform more parental care behaviors, and for a longer amount of time, than parents fed a half ration.

Watch video of the experimental trials, demonstrating the mouthing and fanning behaviors:

Featured scientist: Tina Barbasch from Boston University

Flesch–Kincaid Reading Grade Level = 9.4

About Tina: I first became interested in science catching frogs and snakes in my backyard in Ithaca, NY. This inspired me to major in Biology at Cornell University, located in my hometown. As an undergraduate, I studied male competition and sperm allocation in the local spotted salamander, Ambystoma maculatum. After graduating, I joined the Peace Corps and spent 2 years in Morocco teaching environmental education and 6 months in Liberia teaching high school chemistry. As a PhD student in the Buston Lab, I study how parents negotiate over parental care in my study system the clownfish, Amphiprion percula, otherwise known as Nemo. More here!

SaveSave

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).

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).

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:

New York Times Article, “In Hawaii, Chickens Gone Wild”
Nature Article, “When Chickens Go Wild”
MSU Today, “How Did the Chicken Cross the Sea?“
BEACON, “Feral chickens are a-changing: updates on the rapid evolution of Kauai’s hybrid Gallus gallus”

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:

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.

SaveSave

4.20.16

The birds of Hubbard Brook, Part II

In Part I, you examined patterns of total bird abundance at Hubbard Brook Experimental Forest. These data showed bird numbers at Hubbard Brook have declined since 1969. Is this true for every species of bird? You will now examine data for four species of birds to see if each of these species follows the same trend.

Red-eyed vireo in the Hubbard Brook Experimental Forest

The activities are as follows:

It is very hard to study migratory birds because they are at Hubbard Brook only during their breeding season (summer in the Northern Hemisphere). They spend the rest of their time in the southeastern United States, the Caribbean or South America or migrating between their two homes. Therefore, it can be difficult to tease out the many variables affecting bird populations over their entire range. To start, scientists decided to focus on what they could study—the habitat types at Hubbard Brook and how they might affect bird populations.

Hubbard Brook Forest was heavily logged and disturbed in the early 1900s. Trees were cut down to make wood products, like paper and housing materials. Logging ended in 1915, and various plants began to grow back. The area went through what is called secondary succession, which refers to the naturally occurring changes in forest structure that happen as a forest recovers after it was cut down or otherwise disturbed. Today, the forest has grown back. Scientists know that as the forest grew older, its structure changed: Trees grew taller, the types of trees changed, and there was less shrubby understory. The forest now contains a mixture of deciduous trees that lose their leaves in the winter (about 80–90%; mostly beech, maples, and birches) and evergreen trees, mostly conifers, that stay green all year (about 10–20%; mostly hemlock, spruce, and fir).

Richard and his fellow scientists already knew a lot about the birds that live in the forest. For example, some bird species prefer habitats found in younger forests, while others prefer habitats found in older forests. They decided to look carefully into the habitat preferences of four important species of birds—Least Flycatcher, Red-eyed Vireo, Black-throated Green Warbler, and American Redstart—and compare them to habitats available at each stage of succession. They wondered if habitat preference of a bird species is associated with any change in the bird populations at Hubbard Brook since the beginning of succession.

Least Flycatcher: The Least Flycatcher prefers to live in semi-open, mid-successional forests. The term mid-successional refers to forests that are still growing back after a disturbance. These forests usually consist of trees that are all about the same age and have a thick canopy at the top with few gaps, a relatively open area under the canopy, and a denser shrub layer close to the ground.
Black-throated Green Warbler: The Black-throated Green Warbler occupies a wide variety of habitats. It seems to prefer areas where deciduous and coniferous forests meet and can be found in both forest types. It avoids disturbed areas and forests that are just beginning succession. This species prefers both mid-successional and mature forests.
Red-eyed Vireo: The Red-eyed Vireo breeds in deciduous forests as well as forests that are mixed with deciduous and coniferous trees. They are abundant deep in the center of a forest. They avoid areas where trees have been cut or blown down and do not live near the edge. After an area is logged, it often takes a very long time for this species to return.
American Redstart: The American Redstart generally prefers moist, deciduous, forests with many shrubs. Like the Least Flycatcher, this species prefers mid-successional forests.

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle and Jackie Wilson.

Flesch–Kincaid Reading Grade Level = 10.6

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

There is an engaging video that can be used before the students begin the activity. It introduces some of the researchers behind this body of work, including Richard Holmes, and highlights the importance of the long-term nature of this dataset.
For the full dataset associated with this Data Nugget, check out the Hubbard Brook Data Catalog page. Search for “Bird abundances” in the search bar to find the dataset.
For more information on this research, check out the Hubbard Brook Experimental Forest’s page on their songbird research
For more lessons created from data collected on birds at Hubbard Brook, check out the page “Migratory Birds Math and Science Lessons from Hubbard Brook.”

There are multiple publications related to the data included in this activity:

Holmes, R. T. 2011. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021.
Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13.
Townsend, A. K., et al. (2016). The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird. Global Change Biology 2: 544-555.

SaveSave