Lizards, iguanas, and snakes! Oh my!

The Common Side-blotched Lizard

The Common Side-blotched Lizard

The activities are as follows:

Throughout history people have settled mainly along rivers and streams. Easy access to water provides resources to support many people living in one area. In the United States today, people have settled along 70% of rivers.

Today, rivers are very different from what they were like before people settled near them. The land surrounding these rivers, called riparian habitats, has been transformed into land for farming, businesses, or housing for people. This urbanization has caused the loss of green spaces that provide valuable services, such as water filtration, species diversity, and a connection to nature for people living in cities. Today, people are trying to restore green spaces along the river to bring back these services. Restoration of disturbed riparian habitats will hopefully bring back native species and all the other benefits these habitats provide.

Scientist Mélanie searching for reptiles in the Central Arizona-Phoenix LTER.

Scientist Mélanie searching for reptiles in the Central Arizona-Phoenix LTER.

Scientists Heather and Mélanie are researchers with the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) project. They want to know how restoration will affect animals living near rivers. They are particularly interested in reptiles, such as lizards. Reptiles play important roles in riparian habitats. Reptiles help energy flow and nutrient cycling. This means that if reptiles live in restored riparian habitats, they could increase the long-term health of those habitats. Reptiles can also offer clues about the condition of an ecosystem. Areas where reptiles are found are usually in better condition than areas where reptiles do not live.

Heather and Mélanie wanted to look at how disturbances in riparian habitats affected reptiles. They wanted to know if reptile abundance (number of individuals) and diversity (number of species) would be different in areas that were more developed. Some reptile species may be sensitive to urbanization, but if these habitats are restored their diversity and abundance might increase or return to pre-urbanization levels. The scientists collected data along the Salt River in Arizona. They had three sites: 1) a non-urban site, 2) an urban disturbed site, and 3) an urban rehabilitated site. They counted reptiles that they saw during a survey. At each site, they searched 21 plots that were 10 meters wide and 20 meters long. The sites were located along 7 transects, or paths measured out to collect data. Transects were laid out along the riparian habitat of the stream and there were 3 plots per transect. Each plot was surveyed 5 times. They searched for animals on the ground, under rocks, and in trees and shrubs.

Featured scientists: Heather Bateman and Mélanie Banville from Arizona State University. Written by Monica Elser from Arizona State University.

Flesch–Kincaid Reading Grade Level = 9.8

Check out this video of Heather and her lab out in the field collecting lizards:

Virtual field trip to the Salt River biodiversity project:

Additional resources related to this Data Nugget:

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Green crabs: invaders in the Great Marsh

Scientist Alyssa holding a non-native green crab, introduced from Europe to the American Atlantic Coast. This crab causes many problems in its new range, including the loss of native eelgrass.

Scientist Alyssa holding a non-native green crab, introduced from Europe to the American Atlantic Coast. This crab causes many problems in its new range, including the loss of native eelgrass.

The activities are as follows:

Marshes, areas along the coast that flood with each tide, are incredibly important habitats. They act as homes to large number of species, protect the coast from erosion during storms, and act as a filter for nutrients and pollution. Many species are unique to these habitats and provide crucial support to the marsh. For example, native eelgrass, a type of plant, minimizes erosion by holding sediments in place with their roots.

In an effort to help protect and restore marshes, we must understand current-day issues that are affecting their health. The introduction of non-native species, species that are not originally from this ecosystem, into a marsh may disrupt the marsh ecosystem and threaten the survival of native species. One species that has recently caused a lot of trouble is the European green crab. This crab species was accidentally carried to the Atlantic coast back in the early 1800s from Europe. Since then, they have become extremely invasive and their numbers have exploded! Compared to native crabs, the green crab digs a lot when it searches for food and shelter. This digging uproots eelgrass and causes its population numbers to fall. In many spots where green crabs have been introduced, marshes are now bare and no more grass can grow.

Non-native green crabs caught in trap that has been underwater for 25 hours

Non-native green crabs caught in trap that has been underwater for 25 hours

The Great Marsh is one of the coastal habitats affected by invasive green crabs. Located on the North Shore of Massachusetts, the Great Marsh is known for being the longest continuous stretch of salt marsh in all of New England. Alyssa is a restoration ecologist who is very concerned with the conservation of the Great Marsh and other important coastal ecosystems. She and other scientists are trying to maintain native species while also reducing the effects of non-native species.

A major goal for Alyssa is to restore populations of a native eelgrass. Eelgrass does more than just prevent erosion. It also improves water quality, provides food and habitat for native animal species, and acts as an indicator of marsh health. If green crabs are responsible for the loss of eelgrass from the marsh, then restorations where eelgrass is planted back into the marsh should be more successful where green crab numbers are low. Alyssa has been measuring green crab populations in different areas by laying out green crab traps for 24 hours. Alyssa has set these traps around Essex Bay, an area within the Great Marsh. She recorded the total number of green crabs caught at each location (as well as their body size and sex).

Native eelgrass growing in Essex Bay, an area within the Great Marsh

Native eelgrass growing in Essex Bay, an area within the Great Marsh

Featured scientist: Alyssa Novak, Center for Coastal Studies/Boston University. Written by: Hanna Morgensen

Flesch–Kincaid Reading Grade Level = 8.8

How to Escape a Predator

A stalk-eyed fly and spider interacting in the arena.

A stalk-eyed fly and spider interacting in the arena.

The activities are as follows:

Stalk-eyed flies are insects that have their eyes on the ends of eyestalks, or long projections from the sides of their head. Eyestalks are a sexual signal that males use to attract females. The longer the eyestalks, the more attractive a male is to females and the more mates he gets. For these flies, sexual selection leads to an elaborate trait, just like a peacock’s tail. Males with longer eyestalks have more babies and pass their traits on. Over generations, sexual selection leads to longer and longer eyestalks in males.

However, these eyestalks may come with a cost. Males with longer eyestalks may not be able to move easily and quickly. If they can’t move as fast, males with long eyestalks are potentially worse at escaping predators. Natural selection may select against long eyestalks if males with more elaborate traits are killed and eaten more often by predators. If predators eat males with longer eyestalks before the flies reproduce, they will not get to pass on their traits, regardless of how attractive they are to females.

Variation between stalk-eyed fly species in eyestalk length.

Variation between stalk-eyed fly species in eyestalk length.

In addition to eyestalk length, other traits could affect survival in male stalk-eyed flies. Perhaps the fly’s behavior is more important than its eyestalk length when faced with a predator. When biologists Amy and John first started researching how eyestalk length affected survival, they noticed something intriguing! The flies showed many different behaviors when face to face with a spider predator. Some examples of behaviors included grooming, walking or flying towards the predator, quickly walking or flying away from the predator, displaying forelegs, and bobbing their abdomens. When prey use these antipredator behaviors, predators must put in more work to catch prey, and they will sometimes give up. Therefore, antipredator behaviors may influence the predator’s choice of prey, and certain behaviors that make prey harder to catch could lead to increased survival.

To test whether differences in eye stalk length and/or antipredator behavior were important for survival, male stalk-eyed flies were put in cages with predators. Amy and John filmed the fly behaviors and analyzed the footage. They calculated the frequency and proportion of time that flies were displaying antipredator behaviors. If males with longer eyestalks have lower survival than males with shorter eyestalks, it suggests that longer eyestalks make it harder to avoid predators. However, if eyestalk length has no effect on survival, it suggests that male flies with long eyestalks are able to compensate for their lack of speed through behavior.

Featured scientists: Amy Worthington and John Swallow from Washington State University and University of Colorado, Denver. Written by: Brooke Ravanelli from Denver Public Schools and John Swallow.

Flesch–Kincaid Reading Grade Level = 10.7

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

Videos of a stalk eyed fly and spider predator together in cages. First video shows male fly displaying, grooming, and approaching spider.

A tail of two scorpions

Ashlee & Matt Rowe

Ashlee and Matt Rowe at the Santa Rita Experimental Range in Arizona

The activities are as follows:

Animals have evolved many ways to defend themselves against predators. Many species use camouflage to avoid being seen. Others rely on speed to escape. Some species avoid capture by hiding in a safe place. Other animals use painful and venomous bites or stings to try to prevent attacks or to make being captured more difficult. Anyone who has been stung by a bee or wasp understands how stinging could be a great way to keep predators away! However, there is little research that documents if painful stings or bites deter predators.

The grasshopper mouse lives at the base of the Santa Rita Mountains in Arizona. Scientists Ashlee and Matt have been studying populations of this mouse for many years and wanted to know what the mouse ate. In the mountains, there are two scorpions that make a great food source for the mice. One of the scorpion species has a painful sting. The other species is slightly larger, but its sting is not painful. Ashlee and Matt thought that the use of a painful, venomous sting helped the smaller species avoid most predator attacks.

The Santa Rita foothills - habitat for the grasshopper mouse and scorpions

The Santa Rita foothills – habitat for the grasshopper mouse and scorpions

The scientists collected six grasshopper mice from the wild. Back in the lab, they trained the mice to expect a food reward when they tipped over a small cup containing live prey. Once trained, the mice were used in an experiment. The mice were presented with two cups to choose from. One contained the small scorpion species that has a painful sting. The other cup contained the larger scorpion species that has a painless sting. Ashlee and Matt collected data on which cup the mice chose to approach, inspect, or pursue (by tipping over the cup). They also recorded if the mice attacked or consumed the painless or painful species of scorpion. Each trial ended when the mouse finished consuming one of the scorpions. If painful stings prevent a predator from attacking, they predicted the mice would choose to eat the scorpion species with the painless sting more often.

Watch a video of one of the experimental trials:

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Watch five additional videos on the grasshopper mouse and scorpions:

Images of the southern grasshopper mouse (Onychomys torridus) capturing and eating the painful species of scorpion (Centruroides sculpturatus).

Ot vs Cs 4

Ot vs Cs 1

Ot vs Cs 2

Size differences of the two scorpions used in the experiments (painful Arizona bark scorpion, Centruroides sculpturatus is on the left; painless stripe-tailed scorpion, Hoffmannius spinigerus on the right)size comparison 1 (1 of 1)

Featured scientists: Ashlee and Matt Rowe from University of Oklahoma

Undergraduate researchers involved with the project: Travis Tate and Crystal Niermann from Sam Houston State University; Rolando Barajas, Hope White, and Amber Suto from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.1

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The mystery of Plum Island Marsh

Scientist, Harriet Booth, counting and collecting mudsnails from a mudflat at low tide.

Scientist, Harriet Booth, counting and collecting mudsnails from a mudflat at low tide.

The activities are as follows:

Salt marshes are among the most productive coastal ecosystems. They support a diversity of plants and animals. Algae and marsh plants use the sun’s energy to make sugars and grow. They also feed many invertebrates, such as snails and crabs, which are then eaten by fish and birds. This flow of energy through the food web is important for the functioning of the marsh. Also important for the food web is the cycle of matter and nutrients. The waste from these animals, and eventually their decaying bodies, recycle matter and nutrients, which can be used by the next generation of plants and algae. Changes in any links in the food chain can have cascading effects throughout the ecosystem.

Today, we are adding large amounts of fertilizers to our lawns and agricultural areas. When it rains, these nutrients run off into our waterways, ponds, and lakes. If the added nutrients end up in marshes, marsh plants and algae can then use these extra nutrients to grow and reproduce faster. Scientists working at Plum Island Marsh wanted to understand how these added nutrients affect the marsh food web, so they experimentally fertilized several salt marsh creeks for many years. In 2009, they noticed that fish populations were declining in the fertilized creeks.

View of a Plum Island salt marsh.

View of a Plum Island salt marsh.

Fertilizer does not have any direct effect on fish, so the scientists wondered what the fertilizer could be changing in the system that could affect the fish. That same year they also noticed that the mudflats in the fertilized creeks were covered in mudsnails, far more so than in previous years. These mudsnails eat the same algae that the fish eat, and they compete for space on the mudflats with the small invertebrates that the fish also eat. The scientists thought that the large populations of mudsnails were causing the mysterious disappearance of fish in fertilized creeks by decreasing the number of algae and invertebrates in fertilized creeks.

A few years later, Harriet began working as one of the scientists at Plum Island Marsh. She was interested in the mudsnail hypothesis, but there was yet no evidence to show the mudsnails were causing the decline in fish populations. She decided to collect some data. If mudsnails were competing with the invertebrates that fish eat, she expected to find high densities of mudsnails and low densities of invertebrates in the fertilized creeks. In the summer of 2012, Harriet counted and collected mudsnails using a quadrat (shown in the photo) and took cores down into the mud to measure the other invertebrates in the mudflats of the creeks. She randomly sampled 20 locations along a 200-meter stretch of creek at low tide. The data she collected are found below and can help determine whether mudsnails are responsible for the disappearance of fish in fertilized creeks.

Mudsnails on a mudflat, and the quadrat used to study their population size.

Mudsnails on a mudflat, and the quadrat used to study their population size.

Featured scientist: Harriet Booth from Northeastern University

Flesch–Kincaid Reading Grade Level = 10.2

Click here for a great blog post by Harriet detailing her time spent in the salt marsh: Harriet Booth: Unraveling the mysteries of Plum Island’s marshes

If your students are looking for more information on trophic cascades in salt marsh ecosystems, check out the video below!

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Salmon in hot water

Chinook salmon in Alaska.

The activities are as follows:

Pacific salmon are important members of freshwater and ocean food webs. Salmon transport nutrients from the ocean to freshwater habitats, and traces of these nutrients can be found in everything from trees to bears! Salmon also support sport and commercial fisheries, and are used for ceremonial purposes by Native Americans. Climate change poses a threat to salmon populations by warming the waters of streams and rivers where they reproduce. To maintain healthy populations, salmon rely on cold, freshwater habitats and may go extinct as temperatures rise in coming decades. Warm temperatures can cause large salmon die-offs. However, some salmon individuals have higher thermal tolerance and are better able to survive when water temperatures rise.

Eggs used in QTL experiment

Eggs used in QTL experiment

Salmon individuals and populations may be better able to survive in warmer waters because they have certain gene variants that help them survive under these conditions. Scientists want to know whether there is a genetic basis for the variation observed in salmon’s thermal tolerance. If differences in certain genes control variation in thermal tolerance, scientists can identify the location on the genome responsible for this very important adaptation. Once identified, management agencies could then screen for these genes in populations of salmon in order to identify individuals that could better survive in a future warmer environment. Hatchery programs could also breed thermally tolerant fish in an attempt to preserve this important fish species.

Scientists working in the lab

Scientists working in the lab

To identify the genes responsible for a particular trait, scientists look for Quantitative Trait Loci (QTL). A QTL is a genetic variant that influences the phenotype of a polygenic trait, such as human height or skin color, and perhaps thermal tolerance in salmon. Scientists can find QTL by conducting experimental mattings then examining the phenotypic and genetic characteristics of the offspring. In this study, parent fish from one population of salmon, some that are tolerant to warm water and some that are not, mated and produced offspring. These offspring now had a mix of genetic backgrounds from their parents, meaning that some offspring inherited genetic variants that made them more tolerant to high temperatures and some did not. Each offspring was tested for their thermal tolerances, and had their genomes sequenced. Differences in the genome between offspring that are tolerant and those that are not reveal areas of the genome that are correlated with thermal tolerance and survival in warm water. If differences in certain genes control variation in thermal tolerance, the scientists predicted they could find regions in the salmon genome that are correlated with survival in warm water.

Featured scientists: Wesley Larson, Meredith Everett, and Jim Seeb from the University of Washington

Flesch–Kincaid Reading Grade Level = 10.9

There are two scientific papers associated with the data in this Data Nugget. The citations and PDFs of the papers are below. The lab webpage can be found here.

Check out these Stated Clearly videos to explore DNA and genes with students!

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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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Shooting the poop

The activities are as follows:butterfly

Imagine walking through a forest in the middle of summer. You can hear birds chirping, a slight breeze rustling the leaves, and a faint pinging noise like rain. However, what you hear is not rain – it is the sound of millions of forest insects pooping!

If we look closer to see who is making all this frass (insect poop) you’ll notice there are tons of caterpillars amongst the leaves. You might see caterpillars eating plants and hiding from predators. Some caterpillars might camouflage themselves, while others build shelters from leaves to avoid being seen. Others are brightly colored to warn predators that they have chemicals that make them taste awful.

The silver-spotted skipper is a caterpillar that lives in the forest. They have a variety of defense strategies against enemies, including building leaf shelters for protection. For these insects, the sight and smell of poop might alert predators that there is a tasty meal nearby. Usually caterpillars keep moving and leave their frass behind, but this species builds shelters and isn’t able to keep moving because they need their shelters for protection.

Martha is a behavioral biologist who studies these insects. While raising silver-spotted skipper caterpillars in the lab, Martha noticed that they were making a pinging noise in their containers. Upon further observation, she discovered that they “shoot their poop”, sometimes launching their frass over 1.5m! Martha wanted to figure out why these caterpillars might have this very strange behavior. Perhaps launching their frass is a way to avoid being found by predators.

To evaluate whether the smell of frass helps predators find and locate silver-spotted skippers, Martha conducted an experiment with a wasp predator that eats these caterpillars. She allowed two silver-spotted skippers to build shelters on a leaf and then carefully removed the caterpillars. She then inserted 6 frass pellets into one of the shelters, and 6 beads designed to look like frass but with no smell (control treatment) into the other shelter. She placed the leaf with the two shelters in a cage containing an actively foraging wasp colony (n = 10 wasps). She recorded how many times the wasps visited each shelter (control beads or frass) and how much time the wasps spent exploring each shelter. She expected wasps would spend more time exploring the shelters with the frass than they would the control shelters.

Featured scientist: Martha Weiss from Georgetown University. Written by Kylee Grenis.

Flesch–Kincaid Reading Grade Level = 9.6

Additional teacher resources related to this Data Nugget include:

YouTube videos of the silver-spotted skipper (Epargyreus clarus) “shooting its poop” (aka. ballistic defecation). These videos would be great to show in class after students have read the Research Background section to help engage them with the system.

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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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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).