Melanie ventures into the aftermath of a zombie apocalypse in Episode 45.
Melanie ventures into the aftermath of a zombie apocalypse in Episode 45. Life always finds a way. The genetic variations organisms have are random - accumulated through mutation and other meiotic chance (1:43). Competition and cooperation are important aspects of biological systems - but the playing field isn’t fair when an invasive species shows up (2:40). Who knew mussels could cause so much damage? (4:15) Humans haven’t been the kindest to the environment and our impact on ecosystems is well documented (5:10). Geological and meteorological activity also leads to changes in ecosystem structure and dynamics. Have you heard of the year without a summer? (7:10)
The Question of the Day asks (8:45) During what era are we currently living on the geologic time scale?
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Hi and welcome to the APsolute Recap: Biology Edition.
Today’s episode will recap Ecosystem Disruptions
Lets Zoom out:
Unit 8 - Ecology
Topic - 8.7
Big idea - Evolution & Systems Interactions
If there's anything I’ve learned from watching Zombie apocalypse movies - it's that nature finds a way. The abandoned gas station with rusty metal sign, and vines growing in every available crevice. Unfortunately, humans are some of the great interrupters of the natural world - continuously modifying the habitats around us to suit our own needs. But organisms are resilient, full of grit with adaptations to fill every available niche.
Lets Zoom in:
Starting with the title of the episode - Ecosystem Disruptions. An ecosystem is a community of organisms interacting with the non living, or abiotic, parts of the environment. This is often through nutrient cycles (like carbon and water) and energy flow (like photosynthesis). The rainforest, tundra, prairie and coral reef - are all examples of ecosystems. As for disruptions - the possibilities are endless ranging from deforestation to meteors crashing down from above.
What came first - the chicken or the egg? More applicable to this episode it should be - what came first - the adaptation or the evolution? What you need to remember is that the genetic variations organisms have are random - accumulated through mutation and other meiotic chance. In and of themselves, mutations are not directed by specific environmental pressures. But whether these changes prove beneficial, neutral, or harmful to the organisms IS environmentally dependent. By definition, an adaptation is a genetic variation that is manifested as a trait and favored by selection, providing an advantage to an organism in a particular environment. So, the genetic variation exists first - randomly and naturally - and the environment favors certain variations over others - claiming them as adaptations and driving evolution. And it's a good thing these variations exist because disruptions are coming and only some will survive.
If you’ve ever returned from traveling outside of the country, you’ve likely completed a customs form asking you to disclose any foreign plants or animals you have packed in your luggage. Why? Competition and cooperation are important aspects of biological systems - but the playing field isn’t fair when an invasive species shows up. Governments don’t want you bringing foreign species into the country, for good reason. An invasive species is an organism that is introduced into a new ecosystem, where it typically has no natural predators and rapidly expands. This can dramatically affect ecosystem dynamics as resources are depleted (The government usually cares because it gets expensive to manage). The intentional or unintentional introduction of an invasive species can allow the species to exploit a new niche free of competition - and sometimes even outcompete native organisms for food, water, and shelter. The hoarding of resources can result in uncontrolled population growth and lasting ecological changes.
Consider the Kudzu vine. Kudzu was introduced from Japan to the United States at the Philadelphia Centennial Exposition in 1876 as an ornamental and forage crop plant. The Civilian Conservation Corps and southern farmers planted kudzu to reduce soil erosion and provide shade. However, Kudzu quickly spread and negatively impacted ecosystems because it smothered other plants and trees under a blanket of leaves, hogging all the sunlight and keeping other species in its shade. In 1998, Congress officially listed kudzu under the Federal Noxious Weed Act.
And how about the zebra mussel? This small freshwater mollusk originated in the seas of the former Soviet Union. and spread throughout Europe in the early 19th century with the construction of extensive canal systems. Today, it is even found in much of the United States, including the Great lakes and the Hudson River, Zebra mussels consume an abundant amount of phytoplankton, a microscopic marine algae that serve as the base of many aquatic food chains. They also harm native mussels by interfering with their feeding, growth, movement, respiration, and reproduction. And they impact humans too by colonizing in water supply pipes used for drinking and producing power. No bueno. How about we agree to let organisms be where they were initially evolved to thrive, and not bring them other places. Agree? The U.S. Department of Agriculture monitors these ecological invaders - for a full summary visit invasivespeciesinfo.gov.
You can’t watch any BBC Planet Earth series without experiencing some sort of guilt trip - Humans haven’t been the kindest to the environment and our impact on ecosystems is well documented. Human impact accelerates change at local and global levels. For starters, we’ve introduced new diseases that have devastated native species. Dutch elm disease (not actually Dutch, but studied by them) is a fungus that was introduced to the U.S. from Asia, likely transmitted by beetles. And since beetles can’t swim across the ocean - they came in our ships. The disease has killed hundreds of thousands of American Elm trees across the U.S. since they have no natural resistance. Another infamous fungus, the potato blight - killed about a million people in Ireland in the 1840s. The fungus spreads rapidly through the leaves in warm humid weather causing collapse and decay of the potatoes. New genetic evidence suggests that potato blight originated in South America. Humans are also, unfortunately, having a dramatic impact on habitats through global climate change and activities such as logging, urbanization, and mono-cropping. In its most basic effect, this reduces food, water, and shelter for native species. We need to do better.
Shifting the blame game to the Earth itself for a minute. Because there are repeatedly catastrophic events produced by geological and meteorological activity leading to changes in ecosystem structure or dynamics. One example is, El Nino, a naturally occurring event near the equator which causes temporary changes in the world’s climate. Its effects include increased rainfall and destructive flooding in South America, droughts in Africa, increased ocean temperature, and changes in ocean currents that produce nutrient poor water. The effects of El Nino can last more than a year. Other consistent Earth events include the continual shifting of tectonic plates. The resulting earthquakes and volcanic activity can modify habitats and deplete resources. When Mt. Tambora erupted in Indonesia in 1815, its ash plumes circulated the globe, blocking sunlight and causing a three year period of severe climate deterioration. Known as the “year without a summer” temperatures plunged and vegetation failed. Oh and there's also always the occasional meteor impact and possible extinction - one of theories for the end of the dinosaurs and other forms of life during the Cretaceous Period.
To recap….
Life is resilient - and despite everything we (or earth itself) throws at it, it keeps bouncing back one way or another. It's important to give it a fair chance however. Lets keep species in their native location, reduce our impact on global climate, and avoid habitat destruction. Natural disasters will continue to be part of the puzzle. And if we do find ourselves in a zombie apocalypse situation - my vote is that the plants will be more resilient than us.
This is our last episode of Season 1! Thank you for tuning in each week and interacting with this community on Instagram, Twitter, and Facebook. We will be back next school year with more content to get you prepped for AP Exams.
Today’s Question of the day is about time.
Question: During what era are we currently living on the geologic time scale?