Relative bee species richness from the Old World to Australia.
Bee diversity
Twelve different species of bees swarming a flowery meadow. Etching by J. Bishop, after J. Stewart.
Credit: Wellcome Collection, CC BY 4.0
How many bee species are there? Wait a minute: honeybee, bumble bee, erhm… five? Five hundred? Five thousand? Not even close: the total is well over 20,000 – which means there are more species of bees than of birds and mammals combined.
There's no shame (nor surprise) for bee civilians like you or me in not knowing that. What is surprising, is that even scientists who specialise in bees didn't quite know how those species are distributed all over the world. Until now.
By combining and filtering more than 5.8 million public records of bee occurrences, a team of researchers from China, the U.S., and Singapore have built up the very first comprehensive picture of bee diversity worldwide. And that picture presents a few surprises, both for laypersons and specialists.
Bee ignoramuses will be surprised to learn that the United States is the throbbing heart of bee diversity. The U.S. has far more bee species than any other region on Earth. And by the fact that large tracts of Africa and the Middle East remain terra incognita, in terms of apiary diversity.
Counter-intuitive distribution
Relative bee species richness in the New World. Note the low density in the Amazon Basin.
Credit: Current Biology, open access
In general, there are more bee species in the Northern Hemisphere than the Southern and—confirming previous hypotheses–more in arid and temperate climates than in the tropics.
That goes against the common pattern in biology known as the 'latitudinal gradient', which predicts that species diversity (of most plants and animals) increases towards the tropics and decreases towards the poles. Bees are an exception, with a higher species concentration away from the poles (in what scientists call a 'bimodal latitudinal gradient').
To give that difference some visual immediacy, imagine a graph with one hump in the middle (i.e. the latitudinal gradient) versus one with two humps, one on either side of the middle (i.e. the bimodal latitudinal gradient). In other words: dromedary (one-hump) versus camel (two-hump).
It seems counter-intuitive that bees would thrive better in arid deserts than in lush tropical jungles; but that's because trees–the dominant vegetation type in the tropics–provide less bee food than the plants and flowers that grow elsewhere.
Much-needed baseline
Three ways of measuring species richness in the Americas: (A) richness of polygons, (B) sPCA and (c ) turnover. All suggest a large, distinct bee fauna in the southwestern U.S.
Credit: Current Biology, open access
Also, bees don't like it too wet, unlike their cousins the ants, whose populations peak in the humid tropics. The researchers think humidity may play a role in limiting bee distribution by spoiling pollen resources.
The relative absence of bees from the tropics has consequences for pollination, which in those regions is performed by a wide variety of alternative species: wasps, moths, and even cockroaches.
Previous datasets of global bee distribution were either inaccurate, incomplete, or difficult to interpret. This world map clearly establishes that bees prefer dry and temperate zones to wet and tropical ones. For bee scientists, it provides a much-needed baseline to predict the geographic distribution of bees and interpret the relative richness of species.
While much work needs to be done to fill additional knowledge gaps, this baseline is an excellent starting point, not just for greater understanding, but also for better conservation. Because bees are not just for making honey. In many countries, they're the top pollinator species. And they typically visit 90 percent of the leading crop types.
Carpenter bee (Xylocopa latipes) pollinating a flower in the Indian state of Kerala.
Credit: Charles J. Sharp (Sharp Photography), CC BY-SA 4.0
Yet over the past decades, bee populations have been crashing. In the U.S., honeybee populations have declined by 60 percent between 1948 and 2008. In Europe, 12 wild bee species are critically endangered.
That trend is potentially disastrous for agriculture. More than $550 billion in annual global crops are at risk from pollinator loss. The loss of bees as pollinators would lead to a collapse in crop yields and even entire ecosystems.
Better understanding bees increases our options for protecting them. This study will help pinpoint bee diversity hotspots in otherwise poorly examined parts of the world and help predict how bees will react to climate change–for example when certain regions will get wetter weather.
Protecting bee diversity is especially important and urgent in developing countries, where many of the knowledge gaps are located, and where many crops rely on native bee species for pollination.
Michael C. Orr et al.: 'Global Patterns and Drivers of Bee Distribution' is published in Current Biology.
Strange Maps #1060
Got a strange map? Let me know at strangemaps@gmail.com.
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As part of a new exhibition, the worlds of culture and technology collide, bringing sound to the colors of abstract art pioneer Wassily Kandinsky.
Kandinsky had synesthesia, where looking at colors and shapes causes some with the condition to hear associated sounds. With the help of machine learning, virtual visitors to the Sounds Like Kandinsky exhibition, a partnership project by Centre Pompidou in Paris and Google Arts & Culture, can have an aural experience of his art.
An eye for music
Kandinsky's synesthesia is thought to have heavily influenced his painting. Seeing yellow summoned up trumpets, evoking emotions like cheekiness; reds produced violins portraying restlessness; while organs representing heavenliness he associated with blues, according to the exhibition notes.
Virtual visitors are invited to take part in an experiment called Play a Kandinsky, which allows them to see and hear the world through the artist's eyes.
Kandinsky's synesthesia is thought to have heavily influenced his 1925 painting Yellow, Red, Blue.Image: Guillaume Piolle/Wikimedia Commons
In 1925, the artist's masterpiece, "Yellow, Red, Blue", broke new ground in the world of abstract art, guiding the viewer from left to right with shifting shapes and shades. Almost a century after it was painted, Google's interactive tool lets visitors click different parts of the artwork to journey through the artist's description of the colors, associated sounds and moods that inspired the work.
But Google's new toy is not the only tool developed to enhance the artistic experience.
Artist Neil Harbisson has developed an artificial way to emulate Kandinsky by turning colors into sounds. He has a rare form of color blindness and sees the world in greyscale. But a smart antenna attached to his head translates dominant colors into musical notes, creating a real-world soundtrack of what's in front of him. The invention could open up a new world for people who are color blind.
Reprinted with permission of the World Economic Forum. Read the original article.
The United States of America, land of the free, is home to 5 percent of the world's population but 25 percent of its prisoners. The cost of having so many people in the penal system adds up to $80 billion per year, more than three times the budget for NASA. This massive system exploded in size relatively recently, with the prison population increasing by six-fold in the last four decades.
Ten percent of these prisoners are kept in private prisons, which are owned and operated for the sake of profit by contractors. In theory, these operations cost less than public prisons and jails, and states can save money by contracting them to incarcerate people. They have a long history in the United States and are used in many other countries as well.
However, despite the pervasiveness of private contractors in the American prison system, there is not much research into how well they live up to their promise to provide similar services at a lower cost to the state. The little research that is available often encounters difficulties in trying to compare the costs and benefits of facilities with vastly different operations and occasionally produces results suggesting there are few benefits to privatization.
A new study by Dr. Anita Mukherjee and published in the American Economic Journal: Economic Policy joins the debate with a robust consideration of the costs and benefits of private prisons. Its findings suggest that some private prisons keep people incarcerated longer and save less money than advertised.
Mississippi Blues
The study focuses on prisons in Mississippi. Despite its comparatively high rate of incarceration, Mississippi's prison system is very similar to that of other states that also use private prisons. Demographically, its system is representative of the rest of the U.S. prison system, and its inmates are sentenced for similar amounts of time.
The state attempts to get the most out of its privatization efforts, as a 1994 law requires all contracts for private prisons in Mississippi to provide at least a 10 percent cost savings over public prisons while providing similar services. As a result, the state seeks to maximize its savings by sending prisoners to private institutions first if space if available.
While public and private prisons in Mississippi are quite similar, there are a few differences that allow for the possibility of cost savings by private operators — not the least of which is that the guards are paid 30 percent less and have fewer benefits than their publicly employed counterparts.
The results of privatization
The graph depicts the likelihood of release for public (dotted line) vs. private (solid line) prison inmates. At every level of time served, public prisoners were more likely to be released than private prisoners.Dr. Anita Mukherjee
The study relied on administrative records of the Mississippi prison system between 1996 and 2013. The data included information on prisoner demographics, the crimes committed, sentence lengths, time served, infractions while incarcerated, and prisoner relocation while in the system, including between public and private jails. For this study, the sample examined was limited to those serving between one and six years and those who served at least a quarter of their sentence. This created a primary sample of 26,563 bookings.
Analysis revealed that prisoners in private prisons were behind bars for four to seven percent longer than those in public prisons, which translates to roughly 85 to 90 extra days per prisoner. This is, in part, because those in private prison serve a greater portion of their sentences (73 percent) than those in public institutions (70 percent).
This in turn might be due to the much higher infraction rate in private prisons compared to public ones. While only 18 percent of prisoners in a public prison commit an infraction, such as disobeying a guard or possessing contraband, the number jumps to 46 percent in a private prison. Infractions can reduce the probability of early release or cause time to be added to a sentence.
It's unclear why there are so many more infractions in private prisons. Dr. Mukherjee suggests it could be the result of "harsher prison conditions in private prisons," better monitoring techniques, incentives to report more of them to the state before contract renewals, or even a lackadaisical attitude on the part of public prison employees.
What does all this cost Mississippi?
The extra time served eats 48 percent of the cost savings of keeping prisoners in a private facility. For example, it costs about $135,000 to house a prisoner in a private prison for three years and $150,000 in the public system. But longer stays in private prisons reduce the savings from $15,000 to only $7,800.
As Dr. Mukherjee remarks, this cost is also just the finance. Some things are a little harder to measure:
"There are, of course, other costs that are difficult to quantify — e.g., the cost of injustice to society (if private prison inmates systematically serve more time), the inmate's individual value of freedom, and impacts of the additional incarceration on future employment. Abrams and Rohlfs (2011) estimates a prisoner's value of freedom for 90 days at about $1,100 using experimental variation in bail setting. Mueller-Smith (2017) estimates that 90 days of marginal incarceration costs about $15,000 in reduced wages and increased reliance on welfare. If these social costs were to exceed $7,800 in the example stated, private prisons would no longer offer a bargain in terms of welfare-adjusted cost savings."
It is possible that the extra time in jail provides benefits that counter these costs, such as a reduced recidivism rate, but this proved difficult to determine. Though it was not statistically significant, there was some evidence that the added time actually increased the rate of recidivism. If that's true, then private prisons could be counterproductive.
