My AP Biology Thoughts

Unit 8 Episode #31

Welcome to My AP Biology Thoughts podcast, my name is Saarim and I am your host for episode 31 called Invasive Species. Today we will be discussing invasive species. Before I start, I’d like to give credit to several different sources including the National Wildlife Federation, National Geographic, Eric Guise’s AP Biology videos, as well as UC Riverside Center For Invasive Species Research, New York Invasive Species Information, Wikipedia, National Geographic, the Global Invasive Species Database, and last but not least, the Wisconsin Department of Natural Resources.

Segment 1: Introduction to Invasive Species

Invasive species description

• Non-native, spread rapidly, economic/environmental harm
• Adapts to new area and reproduce quickly - cause some type of harm
• Spread by human activities - pest control, traveling from one place to another, people releasing pets into the wild (goldfish and burmese python), animals and pets could escape from humans
• Impacts and reasons for impacts
• Invasive species = no natural predators or control - no limiting factors
• They can outcompete native species for same resources
• They could prey on many native organisms
• Affects smaller ecosystems and food chains in negative ways
• Biodiversity would be lessened 
• They could change the abundance of certain significant species important to other organisms
• Native species would be defenseless new invader with no limitations
• Invasive species could carry or cause disease, prevent native species from reproducing 
• They can change native food web
• Abiotic conditions impacted - invasive plants affect water quality, tree cover, and can create fuel for wildfires

Segment 2: Examples of Invasive Species

Brown Tree Snake

• Spread through travel
• WW2 - snake transported from South Pacific to Guam - stowaway in ship cargo or in landing gear of aircraft
• Could have been used to suppress the rat populations in Guam which were very high before 1950s
• Snakes - no natural predators+abundant prey = exponential growth
• Snake has caused great damage to forests of Guam - decimated birds and herpetofauna
• Local extinction of half of over Guam’s native bird and lizard species, ⅔ of Guam’s native bat species - reduced pollination by lizards and birds - reduced native plant regeneration and coverage
• Impacted local health and economy
• Venomous - health hazard to infants and young children
• Increased disease carried by insects - kept in check by Guam’s native native lizards and birds - dengue fever and infant salmonellosis
• Cause constant power outages - affect private, commercial, and military activities
• Agricultural pest - insects increase in population due to killing off of birds and lizards; insects reduce crop yields 
• Asian Tiger Mosquito
• Native to southeast Asia - spread along major transportation routes - commercial movement of scrap tires - spread to over 900 countries in 26 states (now in south central US)
• Apparent in Europe, Caribbean, Africa, and the Middle East
• Introduced to California in shipments of ornamental bamboo from south China and were found at the Port of Houston in 1985 in a shipment of used tires
• Domestic in Torres Strait around Australia and Queensland and in Nigeria
• Outcompeted/ridden off species with similar breeding habitats - yellow fever mosquito in Florida and Ae. Guamensis in Guam
• They transmit pathogens and viruses - yellow fever, dengue fever, usutu virus (humans), roundworms and heartworms (animals), wolbachia infection (arthropods) - affects over 40% of arthropods that contract it
• Northern snakehead
• Native to China, possibly to Korea and Russia too
• Entered US when aquarium owners discarded them into local waterways after attaining them from foreign markets or within US
• Could have been released into US waterways for fisherman - fish is important in Asia
• Small prey threatened by feeding juvenile snakehead - zooplankton, larvae, small; adults prey on fish, amphibians, reptiles, birds, mammals - effect ecological conditions and biodiversity
• Kudzu
• Native to China, Japan, and India
• Introduced to NA in 1876 in Japanese pavilion at Philadelphia Centennial Expositions and in Japanese pavilion at New Orleans exposition in 1884
• Promoted by government for erosion control and as drought tolerant, nitrogen fixing legume
• Thousands of acres planted by CCC for hillside stabilization projects
• Aggressive - found in over 30 states
• Kill plants by smothering them under blanket of leaves; break branches; uproot trees; eliminate light availability for trees - kudzu grows on top of things to maximize light amount they receive
• Ability to outcompete (need little nitrogen, acquire resources quickly, etc.) = formation of monospecific plant communities that alter plant communities
• Economic liabilities - millions per year in lost forest production for southern commercial timber producers

Segment 3: Digging Deeper Into Invasive Species

• Methods of control - manual, chemical, biological, cultural, mechanical
• Biological
• Using living organisms to reduce seed production and vigor of invasive populations
• Control organisms come from native range of the target species and require period of study to ensure they remain specific to target population rather than harm the native species
• Biological control time consuming, doesn’t always work
• Worked with galerucella beetle used to control European perennial purple loosestrife
• Chemical
• Using pesticides and herbicides to curb invasive species growth - varies depending on target species and its size, growth stage, and affected species - not done with rare species, etc.
• Manual
• Hand pulling, digging, flooding, mulching, burning, removal of alternate hosts, and destruction/removal of nests, egg masses or other life states - persistence necessary
• Not used on pervasive species
• Mechanical 
• Cutting, girding, mowing, chopping, and making barriers using tools or machines - better with chemicals
• Cultural
• Manipulation of environment - replacement of restoration of plant community
• Invasive species can sometimes be more of a positive over time
• Ex: Study in Proceedings of National Academy of Sciences - researcher looked at seaweed Gracilaria vermiculophylla which spread from Japan with export of oysters
• Foul up fishnets and boat propellers and remove O2
• Provides habitat and shelter for native animals - invertebrates in mud, crab, shrimp, fish, etc.
• Denmark - same algae lived with habitat forming animals, not harmful for mussels/seagrass, provide habitats for invertebrates
• Summary - relation to ecology
• Basically talk about how they harm natural resources, cause competition, extinction - changes in interactions with environment
• Decreased populations = more decreases
• Cause of 6th extinction

Thank you for listening to this episode of My AP Biology Thoughts.   For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.  See you next time!

Music Credits:

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
•  http://creativecommons.org/licenses/by/4.0/

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