Tuesday, January 29, 2013

Monday, January 28, 2013

Dung Beetles and Ball-Rolling: Star Light, Star Bright

Lately, it seems that poo is a popular topic in science news sections, and the dung beetle seems to be up front and center. I suppose that, if you are a dung beetle, you've solved all sorts of poo-related problems. If you recall the dung beetles and ball-cooling post from November, you will remember that these insects use their dung balls to help cool off their feet on the blazing hot African sands. But what if you are a beetle that works at night? You can chuck out the hot feet problem and worry about a whole new one: navigation. A new paper published in Current Biology suggests how dung beetles may solve this navigation dilemma.

For African ball-rolling dung beetles (Scarabaeus satyrus), the best ball rolling strategy is the straight line. The straighter the path the beetle uses to roll the ball away from the dung pile the less likely it is their ball will be stolen by rival beetles. They spent all that time to pinch and roll the poo together, it is a waste of time and energy if it is stolen. Competition is fierce near the dung heap, so a quick and straight exit strategy is best. Getting that ball to roll straight isn't simply a matter of putting one tarsus in front of another, it usually involves exploiting such celestial features as the sun and the moon to orientate. However, it has been observed that many beetles will still manage to orientate along straight paths on clear moonless nights. So what are they using to help them navigate?

To answer this question, a group of researchers set up some beetles in arenas. I know, it already sounds good. On a starlit night, they placed dung beetles with their dung balls in a flattened, leveled, and enclosed circular arena.They first wanted to know how accurately the dung beetles could orientate along straight paths when they were prevented from seeing any celestial cues at all. So they made little hats for them. No kidding. They made little caps from small pieces of cardboard and attached them to the beetles' heads so that their dorsal field of view was obscured but their ventral eyes were unimpeded. Then they let them roll, filming them from above so that the rolling paths could be reconstructed and measured. The sight impeded beetles had path lengths almost 4 times longer than beetles that could see the moonless night sky. Okay, so maybe the beetles are using landmarks, like trees, to help them. To test this, the researchers made another arena that removed all visual cues (including the observer), enclosing it with a circular black cloth wall. Because they removed all observer cues, like the camera, they had to design the arena such that it could tell them when the beetles were at the edge without the researchers filming or looking. So they made the arena wall with a slightly larger diameter than the floor so that there was a gap large enough to allow the beetles reaching the edge to fall from the floor into a trough below, resulting in an audible thump sound. Since ball rolling speed is relative to path straightness (the straighter your path the faster you get to the edge), they just had to time the thumps. Clever. Under a full moon, starry night the beetles took 21.4 seconds to exit the arena and on a moonless, starry night they took a reduced, but not significantly so, 40.1 seconds. The story changes when you put the little beetle hats back on. With the caps they take a significantly longer 124.5 seconds (note: this is not significantly different than an overcast night at 117.4 seconds).

Figure 2 from Dacke et al. (2013) showing the effect of stars on dung beetle orientation

Now we know that stars are important in getting a dung beetle to roll its ball straight. Good. But we also know that most stars are too dim for tiny beetle eyes to discriminate. It is probably unlikely that the beetles are picking out constellations for their navigating needs. So what orientation information are they extracting from a starry sky? To answer this question, the researchers grabbed their beetle arena and took it to the Johannesburg planetarium, where they could manipulate the sky the beetles were seeing. Again, clever. They performed the experiments under five different conditions: (1) complete starry sky, with more than 4,000 stars and the Milky Way, (2) Milky Way only, (3) dim stars, with the brightest 18 stars excluded, (4) 18 brightest stars only, or (5) total darkness. They found that the beetles took the same amount of time to exit the arena, irrespective of whether they could see the full projection of the starry sky or only the Milky Way. This means that the dung beetles are using the bright band of light produced by the Milky Way. The Milky Way is a bright band because it is made up of stars, and when the Milky Way part of the projection (a diffuse streak of light) is removed you still see a sky where a higher density of stars defines the galaxy's axis. In this case, the beetles were still able to use the star density but it took them somewhat longer to reach the edge of the arena. It is high density of light forming into the streak across the sky that is visible, and therefore usable, to the beetles.

There is all sorts of navigating going on in the animal kingdom. Now, it appears that we've found another one. One that may be more widespread than we yet know. We just need to go looking.

ResearchBlogging.orgDacke, M., Baird, E., Byrne, M., Scholtz, C., & Warrant, E. (2013). Dung Beetles Use the Milky Way for Orientation Current Biology DOI: 10.1016/j.cub.2012.12.034

Some press stories on this paper:
National Geographic: "Dung Beetles Navigate Via the Milky Way, First Known in Animal Kingdom"
ScienceNOW: "Dung Beetles Navigate by the Milky Way"
The Naked Scientists: "Dung Beetles Navigate by the Light of the Milky Way"
The New Yorker: "Dung Beetles, Dancing to the Milky Way"
Wired: "Lowly Dung Beetles Are Insect Astronomers"

(dung beetle hat photo credit to Eric Warrant via the NatGeo link above)

Wednesday, January 23, 2013

Battlestar Geologica

A very sciency Battlestar Galactica parody.

Friday, January 18, 2013

Navigating a Large Convention

This infographic was originally made for the International CES meeting, but I think it would work for some of those big science conference poster sessions as well.

(via Column Five Media Visual Storytelling)

Thursday, January 17, 2013

No Death for Death Panels

On Halloween 2009, my costume was a Death Panel. No kidding. And no, I won't show you a picture. As with most political themed costumes, it was funny at the time but was one of those things I thought would melt into the annals of popular culture. I mean, I can't exactly pull that off this year in the way I did then. However, the term "death panel" is one that seems to have perpetuated in the social landscape.

"Death panel" is a political term that originated in an August 2009 debate about federal health care legislation in the U.S. The former Republican Governor of Alaska, Sarah Palin, used it to describe how the new health care law would lead to the rationing of medical care such that decisions about whether the elderly and special needs children would be "worthy of care" would be decided by a death panel of bureaucrats. Palin took a lot of chaff for this remark and later specified that she was referring to Section 1233 of bill HR 3200 which would have paid physicians to provide voluntary counseling to Medicare patients about living wills, advance directives, and end-of-life care options. Take special note of the words "voluntary" and "counseling" in that statement, the fact-checking portion of the media certainly did, reporting Palin's claim as false. The statement was criticized by the mainstream news media, academics, physicians, Democrats, and some Republicans. However, other prominent and outspoken Republicans took it and ran such that it blew up in ways no one could have predicted. It seems that everyone had an opinion, and public opinion often plays an important roll in the success or failure of many policies, like health care.

Public opinion is frequently influenced by misinformation. The media's failure to counter the misinformation about health policy has resulted in a persistence of this misinformation more than two years after the enactment of the Affordable Care Act (ACA), known colloquially as ObamaCare. Unfortunately, it is difficult to overcome "motivated reasoning," people's biases toward their preexisting attitudes and beliefs, which makes them more likely to accept unsupported claims because those claims are consistent with their partisan or ideological views. It certainly doesn't help that the media isn't exactly aggressive about debunking misinformation and even perpetuates it to some degree.

A new study, published online in the journal Medical Care, takes a look at how media corrections might reduce misperceptions about death panels and if these corrections would reduce opposition to health care reform. To do this, the researchers recruited from the SurveySpot opt-in panel, validating their sample by comparing control group responses to poll results. Participants were randomly assigned to versions of a realistic article on the Palin claim modeled on the original Associated Press article but attributed to the fictional "Breakingnews.com." One version included corrective information and the other omitted it. This corrective information was a paragraph at the end of the article explaining why "nonpartisan health care experts have concluded that Palin is wrong." They also collected some additional information about the participants that they thought might influence the effect of the correction on their beliefs and opinions. First, they asked the participants to rate their feelings of Sarah Palin on a 0-100 feeling thermometer (a standard measure in the political science world) where higher values equal warmer feelings. Second, they wanted to assess how knowledgeable or sophisticated their participants were as this can affect how someone resists unwelcome information and hold on to certain misconceptions. So they asked the participants to answer a 5-item political knowledge scale, limiting them to 30 seconds per question to limit their ability to look up the answers online (sneaky, sneaky!).

The researchers found that corrective information can reduce health policy misinformation for some groups. They found that Palin feelings and knowledge moderated the correction's effect, those who felt more warmly about Palin were more likely to believe in death panels. The results also showed "decreased misperceptions about death panels and increased approval of ACA among low-knowledge respondents who viewed Palin favorably." This suggests that fact-checking may improve understanding of policy controversies in these groups. Alternatively, "the correction backfired among high-knowledge respondents who viewed Palin unfavorably, increasing misperceptions about death panels and strong disapproval of ACA." In this case, the motivated reasoning steps in, it is easier for people to believe things they want to be true and disbelieve things they don't want to be true.  So what does all of this mean? Well, it means that public perception about health care is entrenched, and corrective information alone is not enough to overcome motivated reasoning among the more knowledgeable public.

I'm going to end with note to the passionate, the activists (on both sides), and the Internet trolls (who probably won't care regardless): If you've read this far then you also know that I'm not likely to change your opinion of death panels themselves, and I'm not going to try. If you have read this far then you will also have noticed that this post is about a study of public opinion on the matter of death panels rather than death panels themselves (although I describe their origin above and give factual for-your-information links below). As such, if you comment please save us both some time and comment about the study and not about your personal beliefs on whether or not the government wants to kill all of us and our grandmothers. Thanks!

ResearchBlogging.orgNyhan, B., Reifler, J., & Ubel, P. (2013). The Hazards of Correcting Myths About Health Care Reform Medical Care, 51 (2), 127-132 DOI: 10.1097/MLR.0b013e318279486b

More on the Affordable Care Act (ACA) at HealthCare.gov. You can read the full law, look through key features of the law, learn how it affects you, and find a timeline of what's changing and when.

Press release from Duke University's Fuqua School of Business "New Research Shows 'Death Panel' Myth Hard to Correct"

Some articles about death panels:
U.S. News "The Truth Behind Obamacare's 'Death Panels'"
The Daily Beast "The Reality of Death Panels"
FactCheck.org's "Palin vs. Obama: Death Panels"
PolitiFact's "Lie of the Year: 'Death Panels'" 
Snopes "Seniors Beware" and "Euthanasia Counseling"

(image via HowStuffWorks.com)

Sunday, January 13, 2013

The Science of the Friend Zone

I'm liking some of the things posted over on YouTube by Vsauce. He poses some interesting and funny questions and then tackles them in an entertaining and informative manner. Here's his video on The Science of the Friend Zone. What do you think about his conclusions?

Friday, January 11, 2013

The Silverback Playbook: Changing Climate and Ape Distribution

On occasion, I go back to my roots in biogeography and peruse that subset of journals for interesting articles. Admittedly, I now skip over some topics that I used to devour, such as the species-area relationship (the "most general, yet protean pattern" that has recently warranted a special virtual issue). These days, I tend to stop and read articles about distribution patterns, especially as they relate to current problems like climate change.

There are an increasing number of studies that show that climate change will affect species distribution patterns and biodiversity patterns in general. Temperatures, rainfall patterns, sea level changes, etc. are likely to cause geographic shifts in the ranges of plants and animals, altering their relationships with the environment and other species. The common methods for predicting these effects are called bioclimatic envelope models. Basically, these models try to determine the "climate envelope," a description of the climate that defines a species' range, and then map the geographic shift of that envelope under climate change. These types of models are useful for predicting distribution patterns, but they do not inform us about the underlying mechanisms that limit species' distribution and how species will change their behavior and/or the kinds of habitats where they can survive. Think about this behavior part a little more in depth, specifically taking brain size into account. It has been shown that large-brained species are better able to cope with seasonal changes in their environments, buffering themselves against modest levels of climate change, and are more resistant to extinction.

When you think of large-brained species, which ones come to mind? Probably the primates, specifically the African apes (gorillas and chimpanzees). What do we already know about these species? We know that they live in Africa (the most vulnerable of all continents to the effects of climate change), occur in similar habitats (although they differ somewhat in biogeographical ranges), are highly endangered, have highly restricted ranges, have a slow life history, have a large body mass, and have somewhat similar diets. Knowing this, how do you think climate change will affect them?

A study published in the Journal of Biogeography takes a look at how the behavior and distribution of African apes will be affected by climate change. They use a time budget model to investigate how climate warming and behavioral flexibility might affect ape survival. Time budget models are based on individual behavior, how much of an individual animal's time is spent on feeding, resting, traveling and socializing. An animal's time is limited (there is only so much time in a day) and so there is a constraint on the size of a group that can be maintained in a particular habitat which ultimately determines a species' distribution. These types of models can predict distribution as well as the bioclimatic envelope models, as they are based on simple climatological variables, with the added advantage of providing informing us about mechanisms of keeping a species in a particular habitat and evaluating the level of ecological stress in areas where it does occur. They applied this model to data from 20 natural populations of gorillas (Gorilla beringei and Gorilla gorilla) and chimpanzees (Pan troglodytes and Pan paniscus). The model looked at the relationship between climate, group size, body weight, and time budgets. They ran the model to predict ape distribution across Africa under a uniform worst-case climate change scenario, highlighting the importance of individual behavioral requirements for survival. I'm going to save you lengthy descriptions of the model parameters, time budget equations, and model testing. You can thank me later.

The study found that gorillas are more restricted by temperature variation than are chimpanzees. This may cause gorillas to suffer more strongly from the effects of global warming. Their larger body mass and smaller group sizes also increase their risk of extinction even with their behavioral flexibility. This doesn't mean that the chimps are unaffected. They found that chimpanzee communities will be significantly reduced even at locations where they are predicted to survive. The model showed that two critical factors may ultimately determine their survival at these locations: minimum viable community size and minimum party size. Although the distribution for both genera is in the downward direction, the two taxa are predicted to respond differently to changes in climate. Chimpanzees are expected to primarily suffer a reduction in community size because they will need to spend an increasing amount of their time moving and resting. And considering that minimum viable community size is one of the two critical factors, chimps will find it difficult to survive in any of their present habitats and may even go extinct. On the other hand, gorillas already live in small groups and when combined with a dramatic reduction in available habitat (again with the moving and resting time), climate change is predicted to have a stronger effect on their biogeography. However, the authors think that the few surviving populations should be able to maintain present-day group sizes, making them locally stable. Even if the changes in climate were not as extreme, the researchers think that their model would still predict that apes will suffer habitat loss simply due to time budgeting problems that may be reinforced by indirect effects (like temperature on leaf quality). Sure, behavioral flexibility may help, particularly with the more socially fluid chimpanzees, but the environment will support only what it can support (especially for hungry, large bodied creatures).

It is important to note that this study does not include anthropogenic (human caused) influences. Couple those with the doom-and-gloom predictions that the study already makes and it looks like it's bye-bye time for the big apes. That is a bit of a depressing note to leave the post on. Perhaps the good (or happy?) note to leave on is that studies such as these (that take mechanism into account) can give us better ways to predict and preserve optimal habitats, ultimately finding ways to best conserve these species. After all, that is the goal right?

ResearchBlogging.orgLehmann, J., Korstjens, A., & Dunbar, R. (2010). Apes in a changing world - the effects of global warming on the behaviour and distribution of African apes Journal of Biogeography, 37 (12), 2217-2231 DOI: 10.1111/j.1365-2699.2010.02373.x

(image via earthtimes.org)

Thursday, January 10, 2013

The Science Gap

Jorge Cham of Piled Higher and Deeper recently gave a TEDx talk at UCLA. TEDx is a program of local, self-organized events that bring people together to share a TED-like experience. In his talk, Jorge discusses the gap between science academia and the sciences that gets to the public.

p.s. If you are in academia and haven't read the Piled Higher and Deeper comic strip then click this link immediately (http://www.phdcomics.com/comics.php)


Wednesday, January 9, 2013

Karyotyping Socks

Laundry day is fast approaching my household. This got me to smile about laundry, and that is hard to do.

(via Gina Glover)

Friday, January 4, 2013

Burn Baby Burn: Fire, Forests, and Carbon

I know, I know. I've been a bit absent over the last few weeks. I'm going to call laying on the beach in South Florida at Christmas enough of an excuse. That and I was finishing up my Wildland Firefighter course. Yep, I'm now all certified to start and stop forest fires. Should you be afraid? Perhaps. But it got me to thinking about prescribed burning, an area of ecology that I know about but don't regularly keep up with the literature. So I decided to take a look at what has recently been published on the topic and found a nice paper in the journal Forest Ecology and Management about the balance of carbon sequestration and habitat conservation as they relate to fire.

Most people tend to think Fire = Bad. In many situations that's true, but in others fire is actually a natural, healthy process. In the past, various federal and state agencies have instituted wildfire suppression policies because they thought it was the best way to preserve the natural state of the land. All it really did was create a massive amount of fuel loading - lots and lots of fuel (dead logs, leaf litter, etc.) around to burn - which created even larger, more destructive fires. Now we know better, and the idea of a more natural fire regime is being used to control fuels and keep the balance of natural habitats.

Today's paper takes a look at woodlands, a subset of forests that are composed of low density, short trees  that typically have an open canopy with a ground layer made up of shrubs, grasses, and forbs. They can be economically important for lumber and livestock grazing, but they are also naturally important as significant carbon (C) sinks and as a biologically diverse habitat. Fire is known to be an important process in this ecosystem and is managed such that willdfires are allowed to burn unhindered, landscape level fuel management helps contain fire spread, and prescribed burning reduces fuels. This study investigates the effects of past fires on carbon storage, woody vegetation community composition, and habitat suitability. They do this by utilizing a "chronosequence" approach. This means that they grouped and compared stands of trees at different successional stages following fire events. These stands were located in the woodlands of Balcones Canyonlands National Wildlife Refuge (BCNWR), located northwest of Austin, Texas, USA. The dominant woody vegetation in this area is the evergreen Ashe's juniper (Juniperus ashei), with subdominant species including several oak (Quercus spp.) species and Escarpment Black Cherry (Prunus serotina var. eximia). These woodlands are also inhabited by the golden-cheeked warbler (Dendroica chrysoparia), an endangered bird species they used to assess habitat suitability. The mixed juniper-oak are critical for this warbler as they use the stringy, sloughed bark from the mature Ashe's juniper exclusively for nesting material and requre Lepidopteran (Geometridae) larvae that feed on broadleafed foliage during the spring breeding season.

The researchers established 60 plots next to trees that had been used for a previous dendrochronology (tree rings) study. That means that they had the history of the tree from the tree rings, this history including fire scars that could be pinned to exact years. The fires were low-intensity, surface burns that mostly consumed the ground layer, seedlings, and saplings. From this they were able to pick sites with single fire events and then assign their plots into three groups: recent-fire (less than 40 years), old fire (greater than 40 years), and no fire. Then, for each plot, they identified tree species and measured their diameter and heights, collected data on woody debris and leaf litter depths, and collected soil samples for carbon and nitrogen analysis.

The authors found significantly different total aboveground biomass C averages for the 60 study plots. Recent-fire showed 5.25 kg m-2, old fire averaged 6.86 kg m-2, and no fire had 9.18 kg m-2 of C. Previous studies have shown that low to moderate intensity fires have less effects on live biomass, stabilize carbon fast afterwards, and primarily affect trees in an age-specific and density-related way. This study found that "the impact of low-intensity fire on C storage increases for sites with higher proportions of biomass in small trees" (greater than 20cm in diameter) as these are more greatly impacted by surface fires.

 This study's results support that periodic surface fires maintain many forests by favoring fire-tolerant species, such as oaks, and decreasing the density of fire sensitive species, such as juniper. They found that sites with a single fire disturbance had a higher density of oak seedlings than juniper seedlings (though not significantly so), especially in years that had low precipitation in the summer. The densities of mature trees was found to be mainly influenced by differences in topography, herbivory, and historical climate.

I would like to say that all of this added up to a good conclusion about habitat suitability for the golden-cheeked warblers but, unfortunately, they found significant differences. Fire reduces mature tree density, which has a negative impact on habitat suitability, but high intensity fire is related to higher oak recruitment (food source for their food source). Managing these woodland for the golden-cheeked warbler may require both mechanical treatment and the use of fire. The critical core breeding habitat for this warbler includes old-growth stands composed of large, mature junipers and about a 40 percent oak species mix. These stands should be protected from intense fire through the mechanical thinning of the understory and the removal of heavy fuels.

Overall, the authors conclude that fire management can achieve multiple outcomes on a single site. This means that detailed ecological information about the species composition and population structure of an area are needed in order to assess conditions and projections on restoration.

ResearchBlogging.orgYao, J., Murray, D., Adhikari, A., & White, J. (2012). Fire in a sub-humid woodland: The balance of carbon sequestration and habitat conservation Forest Ecology and Management, 280, 40-51 DOI: 10.1016/j.foreco.2012.05.042

More on wildland fires and prescribed burning:
GeoSTAC's Wildland Fires page
University of Florida IFAS Extention's "Benefits of Prescribed Burning"
National Interagency Prescribed Fire Training Center

(image from Texas Department of Agriculture)

Thursday, January 3, 2013

How to Parody Promoting Science to Women

Remember the "Science: It's a Girl Thing" video that I posted a few months ago? Lots of pink, lipstick, dancing, and sexism smeared all over the place. I think we all agree that that was not the best way to go about getting girls interested in science. It really was only a matter of time until a parody was made of it. A group of psychologists from Bristol decided to see what they could do with it. I think they succeeded.

To be fair, the European Commission is trying to promote science to girls, and that definitely needs to be done. Perhaps they didn't succeed in the way they thought they might. But I still recommend that you check out their site anyway:  http://science-girl-thing.eu/en/splash

You can also support the cause by buying a calendar here: http://www.sciencegrrl.co.uk/
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