Monday, June 29, 2015

Loony Locomotion (A Guest Post)

By Emma Doden

For those of us who have worn fins while snorkeling or swimming before, we know how much faster you are able to cut through the water with them on your feet. But as soon as you try to walk on land with those big flippers on, that grace and speed turns into awkward and ungainly steps. You have to concentrate very hard on not falling flat on your face and find yourself thinking that your own two small feet are much more convenient for walking on land than the flippers.

The common loon in flight. Notice how far back on the body its feet are placed!
Photo by Ano Lobb from Wikimedia Commons.
The common loon is a familiar flipper-footed bird for those of us residing in the Northern Midwest. Found on many lakes in the North Woods from late March to September, their black and white plumage, ruby red eyes, and haunting calls make them unforgettable. However, just like any other waterbird, as soon as they come onto land, all of their beauty and poise vanish. Loons do not have the luxury of removing their flippers when they come onto land. Instead they flip and flop clumsily on their bellies, probably feeling just as frustrated as any person frog-stepping with flippers on.

So why do loons have so much trouble walking on land?

Because most of their lives are spent in water, the common loon’s legs and feet are located extremely far back on their bodies, allowing them to swim and dive more efficiently. Loons don’t use their wings to aid in propulsion while underwater, so they need all the power they can get from their legs and feet to catch tasty fish.

The placement of their legs means that they must slide on their belly while on land. Their legs can’t support the weight of their body and so they instead use them to push off of the ground and slide forward. The only time you will find a loon on land is for mating or nesting. Common loons will build their nests on the shore, usually no more than 5 meters from the water, because it takes a lot of effort to belly flop even that short distance!

Watch the video below to see how comical a loon looks when stranded on land:


Though loons are strong fliers as well as divers, coming in for a landing can also be challenging. Their legs are too far back to thrust forward and use as landing gear, so they stick them straight back and make a splash-landing on their bellies, penguin style!

But what makes their legs and flippers so good for swimming and diving?

Common loons propel themselves through the water with sideways strokes of their legs and feet, similar to oars on a boat. Diving birds have leg bones with a long spike-like extension at the knee where very strong muscles connect. This part of their leg acts like a lever when a loon paddles, allowing the leg and foot to be powerfully propelled through the water. Each foot is fairly large with webbing between each toe. When a loon paddles through the water, the webbing fans out and the foot rotates slightly in relation to the body on the downstroke, allowing the maximum surface area to push off of the water. On the upstroke the toes will compress together and the webbing will bunch up so that there is minimal resistance cutting through the water. The motion of the foot splaying out and compressing in with each stroke creates an efficient mode of transportation for the water-loving loon. With legs and feet like these, they are able zoom through the water as fast as fish and dive up to 200 feet!

Loons rarely come onto land, and so it is not often that you will find one of these majestic creatures floundering through the mud of a lakeshore. You are much more likely to see them gliding effortlessly across a lake, until they disappear below the surface. Then you can imagine them easily hunting fish using their powerful legs and feet to propel them while diving. Even more so than wearing flippers to help you swim, just think how much faster you could be in the water with the streamlined body and strong legs and feet of a common loon!

To learn more about common loons and their flipper-foot conundrums visit these websites:

Piper, Walter. The Loon Project.

The Cornell Lab of Ornithology. 2011. Common Loon, Life History. All About Birds.

Evers, David C., James D. Paruk, Judith W. Mcintyre and Jack F. Barr. 2010. Common Loon (Gavia immer), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; The Birds of North America Online.

Michigan Department of Natural Resources. 2014. Common loon (Gavia immer).

Shearwater Seabird Osteology. 2013. Divers/loons: Osteology.

Monday, June 22, 2015

Suicidal Sex

A brown antechinus. Males of this species mate like crazy
for two weeks, then die. Photo by Alan at Wikimedia.
Although most species breed repeatedly over their lifetimes, a select few invest everything they’ve got in a single reproductive bout, after which they keel over and die. This strategy, called semelparity, can be beneficial in species that can have many offspring at once and that are not likely to survive long enough for a second breeding attempt anyway. It is most commonly seen in plants, invertebrates and some fish. It is a rare strategy in mammals, in part because mammalian females do not have many offspring at once and they need to live long enough to care for their young after they are born, which dying early would obviously prevent. Despite this, there are over a dozen species of mammals of which all the males die after their one and only breeding season. How could this possibly be adaptive?


Today at Accumulating Glitches, I talk about how patterns of insect abundance and competitive sperm have pushed some mammals to mate themselves to death! Check out the article here.

Monday, June 15, 2015

Loving to Death

The brown antechinus may look like a
mouse - but that is where the similarities
end. Photo by Glen Fergus at Wikimedia.
Although most animal species breed multiple times throughout their lives, a few oddballs put everything they've got into a single reproductive season, after which they promptly die. This is a rare strategy (for obvious reasons), especially in mammals. One Australian mammal, the brown antechinus, is just odd enough to pull it off.

The brown antechinus is a small insectivorous mouse-sized critter from Australia that in fact is not a mouse at all. It is a marsupial; but unlike kangaroos and koalas, females do not carry their young in a pouch, but rather let them hang off their eight teats for four months. All males die when they are 11 months old (if not sooner) after a single 2-3 week long mating season during which they do little else than mate as often as possible. The mating season leaves all the males (whether mated or not) sterile, coursing with stress hormones, immunosuppressed, and riddled with microorganisms and parasites. Shortly thereafter all the males die, balding and bleeding messes.

The reproductive strategy of putting everything you've got into a single mating season and then dying is only an advantage if you can have many offspring in that single reproductive event. Male brown antechinuses can only succeed in this suicidal mating strategy if they father many of the young of many of the females. As a result, both male and female brown antechinuses are promiscuous (mate with many individuals).

Male brown antechinuses are generally bigger than females, and DNA testing has shown us that in the wild, larger males and males with bigger testes impregnate the most females. Diana Fisher and Andrew Cockburn from Australian National University tested whether larger male brown antechinuses were more likely to get the girls because females were more likely to choose them or because they were outcompeting other males.

Diana and Andrew trapped brown antechinuses and brought them into the lab. In one test, they placed three males in separate nest boxes next to one another in an arena and allowed females to choose among them and mate with whichever one she chose. Surprisingly, when presented with this choice, females did not consistently choose the largest males. They didn't even check them all out - The females mated with whatever male happened to be in the first nest box she entered.

When the researchers put three males into a single nest box and allowed the females to mate, she almost always immediately mated with one of the three males. The next day, the researchers put the female in a nest box with either the two losers from the day before or with two randomly chosen males she did not know. On this second day, females presented with two strangers immediately mated with one male, whereas females presented with the two losers from the day before were more likely to spend more time evading both males, but often eventually mated with one of them. On the third day, the researchers put the female in a nest box with either the loser from the previous two days or with another randomly chosen stranger. Nine out of ten females paired with a stranger mated with him on this third day, whereas only one female paired with a double-loser was willing to mate with him at all. Males that successfully mated on the first day were generally the largest of the three. Loser males that mated on the second day were generally the second-largest and unsuccessful males were generally the smallest.

Interestingly, when given a choice of males one at a time, female brown antechinuses do not seem to care at all about male size. But when males are directly competing with one another, the largest male seems to get the girl. It appears that body size plays a role in the dominance interactions among the males, and that females are paying attention to how the males relate to one another. Additionally, larger males that were more successful in mating also lived longer and had fewer parasites. This could be because it is more stressful to be a loser than to be a winner. Stress increases the production of stress hormones, which in turn reduces immune function. In all of these ways, bigger males are more likely to father more young, who in turn will be more likely to grow up to be big males too... but not for long...


Want to know more? Check these out:

Fisher, D., & Cockburn, A. (2005). The large-male advantage in brown antechinuses: female choice, male dominance, and delayed male death Behavioral Ecology, 17 (2), 164-171 DOI: 10.1093/beheco/arj012

Doing it to death: suicidal sex in "marsupial mice" at The Conversation

Sunday, April 26, 2015

Hiatus for Health

Hi folks,

Due to some recovery time needed for an emergency surgery, I will be on a brief hiatus from The Scorpion and the Frog. But don't go too far - I expect to be back on my feet (or at least back to my computer) in about four weeks.

Behave!
Miss Behavior

Monday, April 20, 2015

Living to Love or Loving to Death?

Biologically speaking, animals are the most successful when they have the most descendents. Because reproduction is such a major focus of animal life, we invest a lot in it and take a lot of risks for it. During breeding phases, animals often forgo eating or sleeping well, risk getting in fights, expose themselves to predators, and spend lots of energy on finding potential mates and courting them. Because many specific costs and risks an animal must face to reproduce are particular to the species, many reproductive strategies have emerged as a result.

One major division in reproductive strategies is iteroparity versus semelparity. An iteroparous species is one that can have multiple reproductive cycles in its lifetime. They include all birds, almost all mammals, most reptiles, fish and molluscs, and many insects. A semelparous species is one that has a single reproductive period and then dies. Semelparous animal species include many insects (such as cicadas and mayflies), some moluscs (including some octopus), and several fish (including Pacific salmon). Only a handful of species of amphibians, reptiles and mammals are semelparous.

A silvereye mother feeds her clutch of chicks. She will have another one next year.
Photo by Benjamint444 at Wikimedia Commons.

The advantages to being an iteroparous species seem obvious (we are one, after all). For one thing, losing your virginity isn't a death sentence. This means that if we are not very good at finding or courting a mate, sex, or parenting the first time around, we get more opportunities to improve. It means that if the conditions are crappy in one breeding season, another season will come around later. And it means that with every breeding season that you have offspring, your individual "success" improves.

Pacific salmon spawn their one and only time. Photo by Steve Hillebrand at
the U.S. Fish and Wildlife Service, available at Wikimedia Commons.

The advantages to being a semelparous species are less obvious. What possible advantages can there be to dying after your first breeding season? But if we think about the "success" of an animal being how many successfully reproducing offspring it has, and not how long it lives, this strategy starts to make sense. A semelparous animal can put everything it's got into its one reproductive event. There is no point in holding back if you're never going to get another shot. As a result, semelparous species usually produce more offspring in their one reproductive event than iteroparous species do in any of theirs.

Several theoretical models have emerged to predict under which circumstances a species would use an iteroparous strategy versus a semelparous strategy. It would make sense that species that have a greater risk of dying early would benefit more from a semelparous strategy. Species in which each additional offspring is less costly to produce and care for than the previous offspring would seem to benefit from an iteroparous strategy. However, strangely enough, the data we have on animal reproductive strategies do not clearly show these patterns.

We still have a lot to learn about these reproductive strategies and the complexities of what makes a species live to keep on loving or love to their death.

Monday, April 13, 2015

Help Protect African Rhinos! (A Guest Post)

by Celia Hein

South Africa is a hotspot for rhino poaching, which is at an all-time high. Rhinos are critically endangered, and in South Africa alone, 1,215 were killed in 2014, which is one dead every 8 hours. South Africa is home to about 70% of the world’s remaining rhinos, and poaching has turned into a highly organized crime syndicate. In many cases, poachers use high-powered rifles, helicopters, and chainsaws. Many of them have had previous military training, and they’re turning our planet’s few precious wildlands into warzones. The park I visited is next on their list.

My name is Celia Hein, and I am studying Wildlife Ecology at the University of Wisconsin – Stevens Point (UWSP). Earlier this year, professors and faculty from UWSP and Rhodes University, South Africa led an amazing group of wildlife ecology students (including me!) on a South African Wildlife Ecology course to study in the field and collect data for research in national parks. During this once-in-a-lifetime adventure, we were lucky enough to spend over a week living in one of these parks.

The park is over 45,000 hectares in area (450 square km or 174 square miles) and houses one of the world’s largest remaining populations of black rhinos. We spent several days with the park manager, who shall remain anonymous for privacy reasons, and discovered that at the park they have to maintain their field equipment, fencing, and pay their dedicated staff of over 100 members with an annual budget of only about 10,000 US dollars! The poachers are better equipped than the park rangers. These brave park rangers are undermanned and outgunned, yet all these professionals we met were so passionate, dedicated, and hopeful. I admire their courage. Many work 10+ hour days in the field, risking their lives, and many of them do not have essential gear like binoculars, flashlights, headlamps, or digital cameras. Many of them do not even have proper boots, let alone a firearm to protect themselves and their rhinos, which are predicted to disappear from our world in about 10 years.


Notice there are no rhinos in this photo of the park. Hacking GPS coordinates
from photos is the #1 way poachers find rhinos. Photo by Celia Hein.
We are doing a used equipment drive and an online fundraiser to supply the rangers of the park. We'll take anything! Flashlights, headlamps, binoculars, sunglasses, hats, GPS, cameras, old backpacks, camping gear, etc. If you want to donate equipment, you can mail it to:

Susan Schuller
403 LRC, WCEE, UW-Stevens Point
Stevens Point, WI 54481

And if you would like to donate money, go here. Please donate to help improve security to protect our rhinos, rangers, and wildlands. 100% of your donation will go directly to this park! And please share on Facebook or email to help spread the word.

Thank you so much!

Monday, April 6, 2015

Behavioral Transplants

Lab mice show off their personalities.
Image by Aaron Logan at Wikimedia.
Twelve Canadian scientists accomplished something we’ve only heard about in science fiction: They transplanted a set of behaviors from one set of animals to another set of animals! And you’ll never guess what part of these animals they physically transplanted to achieve this feat: It was not their brains; It was not their hearts; It was their gut-contents! We have all heard the phrase “you are what you eat”, but scientists have discovered the real truth: You are what you poop.

Today at Accumulating Glitches , I talk about the microbes in our guts that affect our personalities and how swapping personalities may be as simple as swapping poop! Check out the article here.

Monday, March 30, 2015

Gut Feelings

This boy may be influencing who he will marry when
he grows up. Photo by Orrling at Wikimedia Commons.
Animals (including humans) are swarming with microorganisms both on and in our bodies. Humans harbor so many different microorganisms that we have over 150 times more microbial genes than mammalian genes, and it is reasonable to suspect that this scenario is similar for most animals. But before you run to soak in a tub of hand sanitizer, you should realize that many of these microorganisms are actually beneficial to the health of both your body and your mind. Although this field is still very much in its infancy, we have found that the microbes that live in digestive tracts in particular significantly influence their host animal’s behaviors. This connection between our digestive communities and our behaviors has been termed the microbiota–gut–brain axis.

Much of the early research on the microbiota-gut-brain axis was done using specialized mice that have never been exposed to any bacteria. You may think this sounds like a healthy lifestyle, but these so-called germ-free mice have all kinds of health and behavioral problems. They often have digestive difficulties and high levels of anxiety, symptoms common of people with irritable bowel syndrome (IBS). They also typically have deficits in social behavior and increased repetitive behaviors. Similar to autism-spectrum disorders and obsessive compulsive disorder (OCD), these behavioral problems are more likely to occur in males than in females. When faced with a challenge, many struggle with solving the problem and show a higher tendency to give up, symptoms common in patients with depression. Interestingly, simply feeding germ-free mice some species of Bifidobacteria and Lactobacilli bacteria (similar to bacterial strains found in different brands of yogurt) can reduce symptoms of anxiety, depression, cognitive difficulties, autism, and OCD. This has led to a boom in biomedical research on the benefits of probiotics (that contain microbes that live in our guts) and prebiotics (that contain things that the microbes in our guts eat).

Yogurt bacteria. Photo by Josef Reischig at Wikimedia Commons.
These gut microbes don’t just help animals maintain their physical and mental health, they are also involved in complex social behaviors. For example, fruit flies prefer mates that grew up eating the same diet that they grew up eating. However, if they are treated with antibiotics, which kill the gut bacteria, they lose their mate choice preferences. If they are then treated again with microbes from their initial diet (with one Lactobacillus bacteria in particular), they gain their mate choice preferences back. This all makes me wonder, how important is yogurt to choosing the people we date and marry?

How do microbes in our guts affect our brains anyway? Although the answer to this is still mostly unknown, we know that the gut has the potential to influence the brain through multiple means, including hormone production, immune function, and even directly through specific nerves. The specific mechanisms are still being very actively researched, but it is clear that microscopic critters living in our guts likely influence our brains and behaviors in many different physiological ways.

Microbiota-gut-brain axis research is revolutionizing the way we think about health, medical treatments, behavior and even existential questions like who am I? But one thing is for sure: I’m gonna go have another yogurt.


Want to know more? Check these out:

Cryan, J., & Dinan, T. (2015). More than a Gut Feeling: the Microbiota Regulates Neurodevelopment and Behavior Neuropsychopharmacology, 40 (1), 241-242 DOI: 10.1038/npp.2014.224

Ezenwa, V., Gerardo, N., Inouye, D., Medina, M., & Xavier, J. (2012). Animal Behavior and the Microbiome Science, 338 (6104), 198-199 DOI: 10.1126/science.1227412

Monday, March 23, 2015

Komodo Dragons: Their Bite is Worse than Their Bark (A Guest Post)

By Shelly Sonsalla


Komodo Dragon.
Image by Arturo de Frias Marques on Wikimedia.
Komodo dragons are the world’s largest living lizard and can be found only on select islands in the Indonesian archipelago. These massive lizards can grow to be 10 feet in length and up to 150 pounds! Their natural prey includes wild boars, deer, and water buffalo—animals which may outweigh them by several hundred pounds. So how does a lizard, even such a large one, manage to take down prey so much larger than them? The answer lies in their bite.

Komodo dragons’ mouths are a complex interplay of force, toxins, and bacteria. A study by Brian Fry and his colleagues at the Howard Florey Institute in Australia determined the amount of force that a komodo dragon could generate with its bite. What did they find the answer to be? Not much. They found that a komodo dragon’s bite was 6.5 times less than that of an Australian saltwater crocodile. That’s comparable to a 3.5 pound fennec fox! Obviously, this means that the komodo dragon couldn’t possibly bring down such large prey by strength alone. Luckily for them, there are two more factors at play.

Size comparison between a komodo dragon and a fennec fox.
Computer Rendered by Michelle Sonsalla.

The first is venom secreted by a number of venom glands found on the lower jaw. The amount of venom that can be held in these glands totals less than half a teaspoon! This venom has a number of properties meant to kill its prey, properties which prevent the prey’s blood from coagulating and cause painful cramping in the intestines, paralysis, and loss of consciousness. These effects alone would be enough to bring down most prey, but in case they aren’t, there is a final piece of the puzzle—bacteria.

All living things have a multitude of bacteria and fungi that are naturally present on their skin and in their digestive system, but the bacteria found in the mouths of komodo dragons are specialized. According to Joel Montgomery, a researcher at the University of Texas at Arlington, there are 54 species of bacteria found in the mouths of komodo dragons which cause illness and 1 species which has been found to be lethal to mice. These bacteria enter the prey’s bloodstream through its bite and work to infect the creature slowly, causing severe infection within days or weeks.

All three factors of a komodo dragon’s bite work together to take down its prey efficiently and effectively. The bite, though weak, is enough to open the skin and allow the venom and bacteria into the prey’s bloodstream. Once in the bloodstream, the venom works to weaken the animal, which in turn allows the bacteria to gain a foothold to infect, and eventually kill, the victim. These factors allow this large, magnificent lizard, this dragon among beasts, to take down prey much larger than themselves and have helped them survive the extinction of the past’s other great lizards.


References:

Christiansen P, & Wroe S (2007). Bite forces and evolutionary adaptations to feeding ecology in carnivores. Ecology, 88 (2), 347-58 PMID: 17479753

Fry, B., Wroe, S., Teeuwisse, W., van Osch, M., Moreno, K., Ingle, J., McHenry, C., Ferrara, T., Clausen, P., Scheib, H., Winter, K., Greisman, L., Roelants, K., van der Weerd, L., Clemente, C., Giannakis, E., Hodgson, W., Luz, S., Martelli, P., Krishnasamy, K., Kochva, E., Kwok, H., Scanlon, D., Karas, J., Citron, D., Goldstein, E., Mcnaughtan, J., & Norman, J. (2009). A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus Proceedings of the National Academy of Sciences, 106 (22), 8969-8974 DOI: 10.1073/pnas.0810883106

Merchant, M., Henry, D., Falconi, R., Muscher, B., & Bryja, J. (2013). Antibacterial activities of serum from the Komodo Dragon (Varanus komodoensis) Microbiology Research, 4 (1) DOI: 10.4081/mr.2013.e4

Montgomery JM, Gillespie D, Sastrawan P, Fredeking TM, & Stewart GL (2002). Aerobic salivary bacteria in wild and captive Komodo dragons. Journal of wildlife diseases, 38 (3), 545-51 PMID: 12238371