AP Biology class blog for discussing current research in Biology

Tag: predator

Trash, Crops, and Even Pets are on the Menu for these Carnivores

In a recent study, researchers at the University of Wisconsin-Madison and the University of New Mexico found that some of North America’s most prominent carnivores—wolves, mountain lions, bobcats, and foxes—are relying more and more on human sources of food such as trash, crops, and even small pets. In the study, the researchers used hair, fur, and bone samples to identify the diets of seven hundred carnivore species across the upper midwest region of the United States. To identify the diets, chemical isotopes of carbon were taken from these samples to distinguish between human-grown and naturally occurring foods.

Phillip Manlick, the lead author of the study, explains that “Isotopes are relatively intuitive: You are what you eat.” Thus, Human foods, heavy in corn and sugar, have their own distinctive carbon signatures in comparison to the carbon signatures of the diets of prey species in the wild. The ratio of these two isotope fingerprints from the predator samples informs the researchers what proportion of the predator’s diet came from human sources, either directly or from their prey that ate human food first. Our AP Biology class learned that carbon is an essential element in organic compounds. Organic compounds make up all living things which include the human food waste and crops these predators are consuming. Carbon is found in all four organic compounds (Carbohydrates, Proteins, Fats, Nucleic Acids), for carbon’s molecular structure allows for it to create multiple stable covalent bonds with different molecules. Carbon’s covalent bonds enable complex molecules, such as carbohydrates and proteins, that are found in food sources to be formed. 

According to the results of the study, foxes, coyotes, fishers, and martens were the most likely to eat from human food sources, getting about half their food by eating domesticated animals or by foraging in areas that have been disturbed by agriculture. But on average, more than “25 percent of all the carnivores’ diets came from human sources in the most human-altered habitats.”

The reliance on human food sources is not good for the ecosystem, for it increases the overlap in competition for food among these carnivores. There will be more conflicts between species for human food. Furthermore, the reliance on human food sources leaves carnivores susceptible to more human attacks or can change the way species of predators hunt. None of these effects are beneficial to the ecosystem and actually may potentially have harmful ecological consequences.

Personally, I find it a little upsetting that human action is having such interference on the ecosystem and food chain of these predators. In addition, it is even more upsetting to hear that there are very limited options to take that would reduce the reliance on human food sources for these carnivores. Other than securing garbage cans and keeping pets inside at night, there are not many more options. These carnivores are adapting to human urbanization, and this trend will continue as humans keep pushing into these carnivores territories and habitats.

How are ocean conditions harming its animals?

A recent article written by Rachel Nuwer discusses the dangers of ocean acidification and how the ocean environment could compromise the fishes’ ability to swim and feed. The existence of one of the world’s most threatening predators is being threatened by ocean warming and acidification. Sharks might lose their place at the top of the marine food chain due to the changing ocean environment. As carbon dioxide levels rise in the ocean, it increases the acidity of the water. As this factor starts to rise, the teeth and scales of sharks may begin to damage, which compromises their ability to swim, hunt, and feed. According to research published in Scientific Reports, acid-base adjustments have proved to be the first piece of evidence of “dentical corrosion” caused by ocean acidification conditions. After investigating the impact of hypercapnia on a specific shark species and analyzing the acid-based regulation, the team concluded that the denticle corrosion could increase denticle turnover and compromise the skin and protection of the shark species.

A close up on the denticles and scales of a wild shark

The harsh conditions placed on the sharks could cause several consequences and ultimately could affect the whole ocean community. Biologist Lutz Auerswalk states that sharks could be displaced as apex predators, which could disrupt the whole food chain. In addition, great white sharks are already endangered, and these conditions could wipe them out completely, he states. Ocean research Sarika Singh and Auerswald, while studying over beers, stumbled upon a unique idea. After realizing that the high acidity of beet and many other carbonated beverages causes human teeth to erode, they wondered what effect more acidic ocean water might have on shark teeth.

Most studies on ocean acidification examine species that specifically build shells or other calcium-based structures, including corals and shellfish. Because sharks are large and challenging to work with, only a few studies have been conducted about how acidification might impact these animals. Only one paper has examined the effect of pH on sharks’ skin denticles or scales. The study used small-spotted catsharks and exposed them to different environments and filmed their swimming patterns. After analyzing a pectoral fin skin sample, they did not find a specific impact. However, the results were possible constrained by the low carbon dioxide concentration the researches used, compared with the high levels of acidity already present in many oceans.

To begin exploring this question for themselves, Auerswald and Singh conducted an experiment and focused on puff adder shy sharks, a small species that is easy to handle. They decided to investigate the acidification effects on the bigger scales. They divided the sharks into control and experimental groups and observed the results. After a few months, the electron-microscope analysis revealed that the concentrations of calcium and phosphate in the sharks’ denticles were significantly reduced. They noticed damaged scales on many of the sharks as well. Though the corroded scales might not impact their ability to hunt, for larger species such as the great white shark, scales play an essential role in hydrodynamics. Because denticles are responsible for an increase in swimming speed, damaged denticles could slow sharks down and make it more difficult for them to catch prey. Because many animals have been wiped out, we must strive to protect all the species that are deeply impacted by this condition.

Thylacine Brain Structure Reveals Predatory Lifestyle

The thylacine, also known as the Tasmanian Tiger, was the largest carnivorous marsupial of modern times. Native to Australia, Tasmania, and New Guinea, the thylacine quickly went extinct at the start of the twentieth century, following an increase of demand for its pelts. The last known thylacine died in 1936, in Beaumaris Zoo in Hobart, Tasmania, and little is known about the species’ natural behavior. New research however, gives humans a better glimpse into brains and programming behind one of Australia’s most fascinating predators.

Dr. Gregory Berns of Emory University and Dr. Ken Ashwell of the University of New South Wales scanned thylacine brains and reconstructed neural connections in an effort to better understand the specific functions of the thylacine brain and behavior. Only four surviving specimens of the brain exist, and their study gained access to two of them.

“One was provided by the Smithsonian Institution, taken from a male Tasmanian tiger after it died at the National Zoological Park in 1905. The other specimen, loaned to the researchers by the Australian Museum in Sydney, came from an animal that died during the 1930s.”, claimed researchers.

They compared the structure of Thylacine brains to those of Tasmanian devils. The researchers found that the thylacine brains had larger caudate zones than the Tasmanian devil brains. This suggests that thylacines devoted more of their brains to complex thinking, particularly action planning and decision making.

These findings match with what we know of the two animals. Tasmanian devils are known to be scavengers while thylacines were hunters. The neural rewiring done by the researchers provides anecdotal evidence that thylacines occupied a more complex predatory brain than their scavenger cousin, the Tasmanian devil.

These findings are fascinating because they give us new information regarding an animal less than 100 years extinct. It’s seems strange that we had never gathered much information about the thylacine prior to its extinction. However, the resurgence in fascination and curiosity about the animal is exciting to see. Hopefully new research and discoveries will be made in the near future, shedding more light on the thylacines life.



Image result for thylacine

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