BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: ecosystem

Stop Thinking Food Webs are so Simple!!

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On February 27, 2024

In Student Post

We have all learned about food chains and food webs: the producers perform photosynthesis to create their own food (autotrophs), the primary consumers eat the producers for energy (herbivores), the secondary consumers eat the primary consumers for energy (carnivores) and the tertiary consumers eat the secondary consumers for energy (carnivores). We also know that animals can often fit into multiple categories in a food web.

However, it is not quite as often that people explore the effects that just one population change of any part of a food web can have on the rest of the food web; that is to say that a producer decreasing in population would indirectly hurt a tertiary consumer’s population. That is the case because producers are how the food chain gets all its energy in the first place, so with less producers, less energy is in the food chain. Furthermore, as we learned in AP Bio class, each trophic level is merely 10% energy efficient in consuming the trophic level below; thus, each higher trophic level has less energy than the last. Not only is this lack of energy efficiency why there are only a few trophic levels in each food web, but that is why it is so vital for there to be enough (energy) producers in the food web. Additionally, with energy so scarce, any organism’s population size changing can have a dramatic effect on the other populations in its food web.

In the African savanna, Jake Goheen and his colleagues at the University of Wyoming and the Ol Pejeta Conservancy in Laikipia, Kenya, have taken investigating food web relationships to another level. They have spent about 15 years examining how acacia ants (genus Crematogaster) impact a food chain that they are not even a part of consumer wise. They have found that acacia ants protect whistling thorn trees from elephants, which would rip the trees apart: the ants, abundant in the savanna area, consistently protect the trees by swarming in the elephants’ nostrils and biting them from the inside out.

Whistling thorn acacia in Masai Mara

However, with the arrival of a new invasive species theorized to have arrived along with the shipping of human goods, called big-headed ants (Pheidole megacephala), acacia ants have been massively killed off in certain areas. Although the acacia ants are not part of the food chain consumption wise with the whistling thorn trees, the loss of the protection for the trees allows elephants to eat them. Then, much more grassland is opened up. According to Goheen and his colleagues, this open land, with approximately 2.67 times higher visibility than the land typically has (according to a separate study they did), hurts the diet of a higher trophic level predator, lions:

Goheen and his colleagues found that higher visibility in land with less whistling thorn trees helped one of the lions’ main prey sources, zebras, more than it helped them: their chance of taking down a zebra dropped from 62% to only 22% in areas with big-headed ants and thus minimal whistling thorn trees, according to Goheen’s study. Thus, lions pivoted to eating buffalos, which became 42% of their diet. Eating buffalos instead of zebras hurts lions because buffalos are more likely to injure them than zebras are, but buffalos and zebras are still both primary consumers, meaning they both have 10% of the energy of the producers that they eat; that is to say, although buffalos are more dangerous than zebras to lions, lions do not lose energy with their diet swap.

Regardless, more lion deaths from lions having to kill buffalos suggests that the invasive species of big-headed ants that killed off the acacia ants truly caused massive indirect changes in a food web that it and what it killed had nothing to do with consumer wise: to me, it seems apparent that there is much more to food webs than the basic, linear way people usually think about them.

What other ways do you think food webs are affected that we do not realize?

Yes, Some of Us Have Different Human Ecosystems.

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On November 12, 2019

In Student Post

Our human ecosystems inside of us are composed of countless quantities of cells. However, only 10% of those cells are human cells.  Jeroen Raes , a Biologist based in Belgium, made a vital and fascinating discovery about the other 90%. He discovered that there are three different possible ecosystems inside individual humans. Each person has one of these three ecosystems: bacteriode, prevotella or ruminococcus. These ecosystems are composed of hundreds of trillions of harmless bacteria. One could explain our relationship with these bacteria as symbiotic, as we give them a share of food and they return the favor by helping us digest food and convert it to energy. Furthermore, these bacteria help us fight disease, and can even make us happier by triggering our neurons to release more serotonin. Raes’ experiment tested people from the US, Japan, and Denmark. Despite each regions unique diets, Raes claims to have found no correlation between diets and their individual ecosystems. Furthermore, Raes found no correlation between their age/genetic makeup and individual ecosystems.

People who have the bacteriode system “have a bias” toward bacteria that get most of their energy from proteins and carbohydrates. Bacteriode ecosystems also have more bacteria that make greater quantities of vitamins C, B2, B5, and H. On the contrary, both prevotella and ruminococcus ecosystems mostly digest proteins that are sugar coated. Both of these ecosystems also have more bacteria that create vitamin B1 and folic acid.

Raes’ findings have yielded very confusing results. Even Raes has conceded that he is unsure as to why only three total human ecosystems exist. Moreover, Raes admits his sample size of only a few hundred people will increase with more time and funding. Raes hopes to further his research on these unique human ecosystems, and potentially find links to obesity, diabetes, Crohn’s disease, and autism.

 

Proteus Vulgaris, an example of a type of human bacteria found in the gastrointestinal tract.

Did You Know Plants Can Talk?

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On October 14, 2018

In Student Post

 

For thousands of years language has been a crucial part of cultures around the world, and a method unique to humanity of transmitting ideas, thoughts, emotions between us. Language has allowed us to work harmoniously together for our mutual improvement and survival. Recently, however, two researchers, Dr. Kim Valenta and her colleague Omar Nevo, have discovered that plants too, have developed their own unique and intricate method of conveying information to their pollinators; “the easier it is for fruit eaters to identify ripe fruits, the better the chance for both [, the plant and the fruit,] to survive.

The most vivid example of plant communication can be found in Madagascar’s Ranomafana National Park and Uganda’s Kiabale National Park where berry plants have evolved “to match each animal’s sensory capacities, [thus] signal[ing] dinner time in the jungle…” Dr. Valenta and Nevo analyzed the exact colors of each fruit with a spectrometer, and “with a model based on the visual capacities of the seed-dispersing animals, they also determined who was most likely to detect different fruit colors contrasting against an assortment of backgrounds.” The researchers concluded that “the colors of each fruit were optimized against their natural backdrops to meet the demands of the visual systems of their primary seed dispersers,” i.e. pollinators. Thus, red-green color-blind lemurs, in Madagascar were best able to detect the fruit with a blue yellow color scheme and monkeys and apes in Uganda, with tricolor vision like humans, were clearly able to distinguish red berries against a green backdrop.

Also recently discovered was that plants can communicate to their pollinators through scent. Dr. Nevo performed a scent-based study on the lemurs in Madagascar. His team collected various ripe and unripe fruits from all over the jungle of Ranomafana. “He suspected the leumur-eaten fruits would have a greater difference in odor after they ripened than the bird-eaten fruits.” To discover exactly how this scent-based communication worked, Nevo used the “semi-static headspace technique.” From this experiment it was confirmed that “fruits dispersed solely by lemurs produced more chemicals and a greater assortment of compounds upon ripening. It is now known that wild lemurs actually spend quite a lot of time smelling for the vivid difference in odor between ripe and unripe fruits in the jungle.

It is astonishing how plants have evolved over the years to be able to communicate with their pollinators for the betterment and expansion of their species. I would be interested to find out, what other organisms communicate (single cellular, multi-cellular, etc.) and what kind of information they find necessary to convey to others for their survival?

 

 

 

 

Hide Your Kids, Hide Your Wife, ‘Devil Weed’ is Coming.

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On October 16, 2017

In Student Post

No, it’s not what you’re thinking, but Devil Weed is invasive brown algae disrupting ecosystems across the globe. This seaweed, Sargassum horneri, has existed along Japanese and Korean shores and has now popped up along California coasts. The major concern in each location is the Devil Weeds rapid and unstoppable growth. It pops up in rocky reef areas, harms and alters surrounding wild life, and completely takes over like a weed. Evidently, its controlling nature inspired its name and has raised great concern for affected ocean life as it continues to grow at an unbelievable rate.

S. horneri  is a 10 to 50 foot tall annual species, completes its life cycle in one year, though there are “overlapping generations” in the same seasons. This allows it to remain in the same habitats for years and years, forming dense ‘forests’ and hijacking specific areas.

Image Credit: Sargassum

Researchers at the Santa Barbara Costal Long Term Research Project (LTER) and National Science Foundation (NSF) used various approaches to try and learn how to clean and control Devil Weed in the most efficient and powerful way. This proved a challenge because of the seaweeds unpredictable and unknown behavior, but the researchers were able to tests some ideas. They experimented and discovered that partially cutting the stems of the seaweed, instead of completing removing the plant, would stop the plant from self-reproducing and it would later die off. They also discovered that the best way to remove a lot of the Devil Weed was to use an underwater suctioning machine though this only allowed two scuba divers to work at once and it was very time consuming and costly. Lastly, they figured out that the plant thrives in warmer climates and reproduces the most during those times, but overall they couldn’t find an efficient and effective removal approach like they had hoped for.

The biologists concluded that it’s better to attack S. horneri during the early winter by slashing the stems of the seaweed and using an “underwater suction device”, though these tactics only slow down its spreading and make no significant long-term impact. This issue should be of concern of many and I believe we all should care about our underwater ecosystems. So with that being stated, if more research isn’t done, awareness isn’t raised, and action isn’t taken S. horneri  will continue to grow at rapid rates. It will most likely harm and take over big portions of our underwater life and this intrusive and cynical behavior is only typical, of a Devil.

Pythons to Blame for Increase in Dangerous Mosquitoes in Florida

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On October 11, 2017

In Student Post

The Invasion of Burmese Pythons in Southern Florida has been well documented over the last few years, and as they increase in number in the Everglades, numbers of many mammals have diminished. The addition of an extra top predator such as the Burmese Python, the second largest snake in the world, growing up to about 19 (19!!!) feet long, has dire implications for the ecosystem of the Everglades and of Florida, but they pose a danger to the humans in the area as well!

That’s right, the Burmese Pythons are causing problems for Floridians. No, Floridians are not soon-to-be victims of a Python takeover, but the disruption of the Everglade ecosystem has begun to become apparent. As Burmese Pythons have lowered numbers of countless different mammals across the Everglades, mosquitoes have less variety among the animals they drink the blood from, per ScienceDaily. As a result, Mosquitoes have been taking more blood from the mammals that remain, most notably the hispid cotton rat. Mosquitoes in the area are now taking more than 75 percent of their meals from this rat, which is a massive 422 percent increase since 1979. Burmese Pythons were first reported in the area in the 1980s. The hispid cotton rat, which so many mosquitoes feed on now, hosts the Everglades Virus, which is transferred to humans by mosquitoes. As if we didn’t have enough reasons to hate mosquitoes. The hispid cotton rat is one of the only hosts for the virus, which causes “fever, headache and even encephalitis” in humans, according to the same ScienceDaily Article.Sigmodon hispidus1.jpg

This new research is not only  relevant because of the increased hatred we all now have for mosquitoes, though. It also represents a landmark in research on invasive species. Nathan Burkett-Cadena informs ScienceDaily that “As far as I am aware, this is the first time that researchers have found that an invasive predator (such as the python) has caused an increase in contact between mosquitoes and hosts of a human pathogen.”

So, python invasions lead to more virus-carrying mosquitoes in the Everglades. Does this make you as uncomfortable as it makes me? Let me know what you think, leave a comment. I for one am glad to be far away from both the pythons and the Everglade mosquitoes.

 

Photos:

James Gathany for CDC https://commons.wikimedia.org/wiki/File:Sigmodon_hispidus1.jpg

Susan Jewell for USFWShttps://en.wikipedia.org/wiki/Burmese_pythons_in_Florida#/media/File:Burmese_python_(6887388927).jpg

 

Fish might be shrinking!

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On October 11, 2017

In Student Post

To all the seafood lovers, you are being warned here first! The tiny piece of tuna on your plate will soon become even smaller due to climate change. Fish in the ocean will struggle to breathe due to the increasing water temperature, and many species of fish will likely shrink. According to a study published in Global Change Biology, the author predicts a decrease in sizes of the fish by as much as 30 percent. As Nexus Media explains, fish are cold-blooded animals, which means that they cannot regulate their own body temperature. Daniel Pauly, the study’s lead author and a University of British Columbia research initiative, say that due to the increase in ocean temperature, fish will have a higher metabolic rate and have to consume more oxygen. The whole metabolisms in the fish’s body, all the chemical reactions, are accelerated.

Credit:  Attribution license: Taras Kalapun,

Source

So if the fish need to have more oxygen intake, why not just grow bigger gills? In Pauly’s research, he suggests that growing bigger gills won’t help. According to the article, the gills being mostly two-dimensional, just cannot keep up with the three-dimensional growth in the rest of the fish’s body. When a fish grows 100 percent larger, its gill could only grow about 80 percent or less, according to the study. When a gill can no longer supply enough oxygen for a fish’s larger body, the fish will just stop growing larger all together, according to William Cheung, a director of science for the Nippon Foundation. In order to match the decreased supply of oxygen, fish will have to lower their demand, which means that fish of all kinds will shrink as a result of climate change.

There is already evidence to the phenomena of fish shrinking due to climate change, researchers in the North Sea have found that fish stocks like haddock and sole had decreased in body size over the past couple decades, and it is primarily due to climate change since commercial fishing and other factors have been corrected. Furthermore, the entire ecosystem will be affected since the larger fish eat the smaller ones, and a change in body size would alter food web interactions and structure.

To read more about other impacts of climate change on marine species.

Sources:
https://www.scientificamerican.com/podcast/episode/climate-change-might-shrink-fish/

White-Nose Syndrome Threatening Brown Bat Species

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On January 16, 2015

In Student Post

In 2006, hibernating bats in upstate New York were identified with white-nose syndrome , a disease that produces a white fungal growth around the wings, mouth and nose of bats. The disease is a huge problem for North American bats, with it killing at least 6 million brown bats and the disease now spreading from New York to Mississippi and Canada. The disease may even threaten the entire bat species and disrupt the ecosystem. Scientific researchers have been studying WNS for over a decade and only recently have they developed a reason for its lethal effect on the North American bat population.

Researchers from the US Geological Survey and the University of Wisconsin learned that the fungus Pseudogymnoascus destructans kills brown bats by “increasing the amount of energy they use during hibernation”. When bats are hibernating during the winter, they must carefully save up their energy to survive without eating until the winter ends. The fungus drains bats of their energy and forces them to wake early and either starve or freeze to death. The study done by USGS measured how much fat was burned and at what rate during hibernation between non-infected and infected bats. Dr. Michelle Verant, a USGS National Wildlife Health Center scientist, found that bats infected with WNS used twice as much energy as the healthy bats during hibernation and had “potentially life-threatening physiologic imbalances that could inhibit normal body functions”.

The immune system of bats is very tolerant of pathogens and diseases that can be lethal to humans, like ebola and even some cancer cells. Bats are immune to many viruses and rarely show signs of disease so the visible white growth on the bats poses a huge threat to the ecosystem. Dr. David Blehert worked with Dr. Verant at the USGS National Wildlife Health Center and the WNS is scary because “here we have an animal that can survive some of the scariest viruses we know, and it’s undone by a common soil fungus.”

Brown Long-eared Bat

Brown Long-eared Bat

 

Main Article:

http://www.science20.com/news_articles/winter_hibernation_energy_drain_how_whitenose_syndrome_kills_bats-151997

Other Articles of Interest:

http://www.eurekalert.org/pub_releases/2015-01/usgs-hdw010215.php

http://www.nytimes.com/2015/01/13/science/no-time-for-bats-to-rest-easy.html?ref=science&_r=0

http://www.biomedcentral.com/1472-6793/14/10

http://en.wikipedia.org/wiki/White_nose_syndrome

 

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