Human-Guided Evolution Closer Than You Think (Skeptical Inquirer)

9 minute read

Evolution is often thought of as a solely long-term process. But the conception that its effects are only seen after millions of years ignores a crucial part of the evolutionary process: adaptation. Because we tend to fixate on the drastic changes caused by evolution over huge timescales, it’s easy to ignore the small variations between generations that add together over time to form the big evolutionary changes we focus on. This unintentional side-lining of small adaptations can blind us to the ways in which humans are directly affecting the evolutionary processes of nature. From tuskless elephants to fish that can’t smell, animals are developing specialized adaptations to allow them to live in ecosystems that have been disrupted and altered by mankind. These adaptations are one step in the evolutionary process that already bears the unmistakable marks of humanity’s influence.

Just as humans are changing the planet, they’re changing the fauna that inhabit it. Here are some examples of how.

You can read the entire article here: https://skepticalinquirer.org/exclusive/human-guided-evolution-closer-than-you-think/

Leafcutter Ants are Farmers Who Grow Fungi

2 minute read
Originally posted here: https://mcgill.ca/oss/article/did-you-know/did-you-know-leafcutter-ants-are-farmers-who-grow-fungi

Leafcutter ants can strip as much as 17% of the leaf biomass from plants in their ecosystem and can clear entire trees in under a day. Next to ours, leafcutter ant society is the most complex society on earth. They build nests that can contain thousands of rooms and cover up to 0.5 km2, a feat that is necessary since a mature colony can contain more than eight million individuals.

But if they’re not eating the leaves that they carry home, what are they doing with them?

Farming. Leafcutter ants use leaves as their fertilizer to grow their crop: fungus.

They cultivate their fungal gardens by providing them with freshly cut leaves, protecting them from pests and molds, and clearing them of decayed material and garbage. In return, the fungus acts as a food source for the ants’ larvae. The ants are so sensitive to the fungi’s needs that they can detect how they are responding to a certain food source and change accordingly. This symbiotic relationship also benefits from a bacterium that grows on the ants’ bodies and secretes antimicrobials, which the ants use to protect their fungi.

Adult ants don’t feed on the fungus, but rather get their nutrients from leaf sap. Smaller adults often hitchhike on leaves being carried back to the nest to opportunistically feed on the sap, as well as protect the carrier from flies and to check that the leaf isn’t contaminated with other fungi.

Leafcutter ant society is divided into castes, with each group having a different role to play. The largest ants, called Majors, act as soldiers and heavy lifters. They guard the nest and help to clear out the highways between the nest and a food source. The next smallest caste, the Mediae, is made up of generalists, cutting and transporting the bulk of the leaves for their colony. Next in size are the Minors, who protect the foraging path and food source, and the smallest ants, the Minims, work exclusively at home, tending to the larvae and fungus garden.

Some Minims work exclusively as garbage collectors, removing decaying organic matter from their fungal gardens and transporting it to dedicated garbage rooms placed well below the rest of the nest. After becoming garbage collectors, these ants will never interact with the fungus or the queen, to prevent any disease from being passed onto them.

Leafcutter ants are often presented as a single species of ant, but in reality, there are 250 species of ants which practice fungus farming. Besides their agrarian tendencies, these ants have something else in common: queens. When it comes time to establish a new colony, winged virgin queens-to-be take part in their nuptial flight and mate with many different males to collect sperm. They then set out to find an appropriate place for a new colony, bringing with them a piece of the fungus to seed their new fungal gardens.

Trees Avoid Touching Each Other Due to “Crown Shyness.” the Results Are Beautiful Webs of Leaves.

1 minute read
Originally posted here: https://mcgill.ca/oss/article/did-you-know/trees-avoid-touching-each-other-due-crown-shyness-results-are-beautiful-webs-leaves

Trees might be tall and strong, but they are still a bit sheepish.

Crown shyness describes the phenomenon of a tree’s leaves withdrawing from the leaves of other trees. It results in beautiful webs of almost touching canopies, but why do trees do it?

There are a few theories for trees’ bashful growth patterns. Some believe that blowing wind causes branches to hit their near neighbours, causing damage to their leaves and buds, and as a result, trees then limit growth at these locations to avoid further damage. This theory makes sense, given that crown shyness is exhibited between trees of different and same species, and sometimes even between branches of the same tree. When researchers were able to prevent wind-induced collisions between trees, they filled in the canopy.

Another theory for timid tree branches hinges on their ability to sense nearby plants. Tree leaves have been shown to detect far-red light bouncing onto them after hitting trees close to them. Branches would naturally try to avoid other plants that could shade them or prevent their growth, creating a gap in the canopy.

This theory could also explain why some trees do not exhibit crown shyness when interacting with trees of their own species. Studies have shown that some plants that sense nearby relatives will position their leaves to avoid casting shade on their kin, even at the cost of shading themselves. Who knew that plants could act cooperatively?

Some species have even adapted to take advantage of crown shyness, choosing to grow into shapes that compliment nearby trees, so that they don’t have to compete for canopy room.

You Can Still See the Division of East and West Berlin from Space

Originally published here: https://mcgill.ca/oss/article/did-you-know-technology/you-can-see-division-east-and-west-berlin-space

Berlin might be united now, but evidence of its 40-year history of division still remains. 

This photo, taken by Commander Chris Hadfield, shows a divided Berlin, with the East appearing orange and the West white. But why?

What used to be East Berlin still utilizes nearly 40,000sodium-vapour lamps, which appear orange, while what used to be West Berlin has upgraded to mercury vapour, fluorescent or LED lamps that appear white.

Sodium-vapour lamps have fallen out of favour since they give off primarily yellow light that inhibitcolour vision in the dark. They also contain mercury, which makes them potentially toxic if broken and difficult to dispose of,and have lifetimesroughly half that of LED bulbs.

Your Allergies Are Getting Worse Because of Climate Change

Photo by Matteo Zamaria Photography
Originally posted here: https://mcgill.ca/oss/article/did-you-know/your-allergies-are-getting-worse-because-climate-change

If you feel like your recent periods of coughing, sneezing and shaking your fists at the trees for producing so much pollen are getting longer, you’re probably right.

It seems that climate change is having an effect on the duration of plants’ pollination seasons. Warmer and wetter winters are allowing pollination to start earlier and last longer, sometimes as much as 27 days longerChanging carbon dioxide levels in the air can also affect how much pollen plants produce… and it’s not going down. The net effect is longer, harsher seasons for allergy sufferers.

Seasonal allergies were first reported around the time of the industrial revolution, though we’re not certain why they sprang up then. It could be that the rapid urbanization and increase in human greenhouse gas emissions triggered the phenomenon of seasonal allergies. Even now, pollen allergies are on the rise in urban centres. As the temperature increases, due to our elevated emissions, allergenic species are able to migrate into areas they previously couldn’t thrive in. This results in new allergies as well as worsening of previously existing ones. Pollen counts are raised by windy and dry conditions,and lowered by wet and cooler ones, so staying indoors on the hottest of spring days is a good idea. You might also want to consider what you can do to mitigate climate change. After all, the climate is unequivocallyundeniably changing. And not for the better.

Ostriches Do Not Really Stick Their Heads in the Sand

Originally published here: https://mcgill.ca/oss/article/did-you-know/ostriches-do-not-really-stick-their-heads-sand

Despite popular misconception, ostriches do not stick their heads in the sand. This myth originated in ancient Romeand is so pervasive that it’s used as a common metaphor for someone avoiding their problems. It’s thought that this belief began after observing ostriches nesting and being stalked by predators. First, it must be noted that as majestic as Ostriches are, they have very small headscompared to their bodies, so it’s perhaps easy to see why so many people believed their heads were simply disappearing underground. Furthermore, these birds do not build nestslike other fowls, choosing instead to bury their eggs in a hole in the sand. They routinely use their beaks to check on and turn their eggs, which may give the impression of sticking their heads right into the dirt. Last, when faced with danger, ostriches will lower their heads to the ground in an attempt to blend into their surroundings and becoming a lesser target, a behaviour that surely fooled more than one person into thinking their heads weren’t there at all.

If you’d like to learn more about ostriches, check out this Animal Planet documentary!

Latex emitting dandelions

Originally published here: https://mcgill.ca/oss/article/did-you-know-environment/latex-emitting-dandelions

Ever snap off a dandelion head and see the white liquid seeping out from the stem? It turns out that fluid isn’t sap or poison, but a defense mechanism, in the form of latex! The Lithuanian word for dandelions is ‘pienė’, which literally translates to milky, for the white liquid. Latex is produced by cells called laticifers, which exist in more than 20 000 plant species, as well as some fungi. Dandelions are fairly special though, as only 6% of temperate plants produce latex, versus 14% of tropical ones.