Lecture 2: Are Invasions a Unique Form of Global Change? Flashcards
1
Q
What are the two main opposing views of human-assisted invasions
A
- Modern invasions are nothing new
2. Modern invasions are an unprecedented global change
2
Q
Describe the opposing view that modern invasions are nothing new.
A
- the magnitude and impacts of human assisted invasions are similar to those in the fossil record.
- basically arguing that they are nothing new and the the earth has experienced them, sometimes with waves of many sp and often independent single sp colonization event. Highlighting this is true for extinctions, such that many prehuman extinction and invasion events were of at least comparable magnitude to current ones.
- TRUTH THOUGH: BUT BUT BUT the combination of the rate and magnitude, as well as the distances and agency involved, that separates human driven invasions form self perpetuated colonization events. Invasive sp are a pervasive and major component of HUMAN INDUCED global change.
3
Q
Describe the other opposing view that modern invasions are an unprecedented global change.
A
- current mass invasion event is unique in scale and impact.
- there is evidence of invasions in geographical past but these events were episodic, differing greatly from human assisted invasions in spatial and temporal scales and the number + diversity of organisms involved in LONG distance dispersal.
- should be viewed as global change
- BUT prehistoric invasions are important for examining and learning about species area effects, evolutionary effects, biotic resistance and impacts of novel functional groups introduced to naive biota. BUT regardless they only provide a limited insight to synergistic effects of invasions and other environmental stresses, the effect of propagule pressure, global homogenization -> which all characterize the present situation.
4
Q
What are the four propositions of why invasions are global change.
A
- invasions are occurring at unprecedented rates and spatial scales
- Virtually all of these are the result of human activities
- They are eroding the distinctiveness of biogeographic realms
- This phenomenon is a unique form of global change
5
Q
Explain natural invasion (range expansion) !
A
- invasion without direct human influence
- usually involves movement along corridors
- sequential, small-scale movements
- predictable
6
Q
Explain human-assisted invasion!
A
- movement across barriers
- often involves long-distance jumps
- difficult to predict
- barrier (geographic or physiological)
7
Q
List species colonizing the great lakes by point caspian species
A
- 145 alien species have invaded the great lakes
- through ballast water and canal
- ruffle, zebra mussel, quagga mussel, rud, round goby, tube nose goby, New Zealand mudsnail, Blueback herring, amphipod, water flea,
- two key traits for ballast water transport = planktonic larvae and parthenogenetic reproduction
- ability to tolerate a broad salinity tolerance
- theorized that as the cumulative number of attempted and successful introductions increases, each perturbing the system and potentially facilitating one another, the recipient community becomes more easily invaded over time. Especially when invaders co evolved together
8
Q
Explain the quagga mussel turning up in western US control plan
A
- plan to use chlorine or copper sulphate to kill any mussels or larvae in the 386km long canal. Luckily quagga mussels prefer deeper, cooler water
- Introduced to great lake, then moved out west.
- Attaches to boats
- Can live out of water for awhile
- Enough moved to start a reproducing pop
- If they don’t establish the first time we provide introduction chances many times before a successful establishment occurs (lots of boat use).
9
Q
Explain alewife invasion of great lakes
A
the alewife seems to have entered the Great Lakes at about the time of canal building in the late 19th century. Perhaps using the Erie as a mode of transportation, the alewife range increased greatly as they entered the Great Lakes and from there became established in all five lakes; cold temperatures in the winter have been known to kill off large populations periodically, but typically the alewife can survive most winter temperatures even in the northern parts of Lake Superior. These introduced populations have forsaken the second part of the anadromous life cycle, and do not return to the sea as adults. Instead, they spend the entirety of their life in fresh water. There are also a number of separate isolated inland populations in Virginia, Kentucky and Tennessee.
- eerie canal is what allowed them to overcome the Niagara falls geographic barrier
- natural range: the alewife used to be a purely anadromous species, breeding in freshwater rivers but returning to the ocean to complete their life cycle. They were typically found from Newfoundland to the Carolinas, preferring depths of approximately 150 to 350 ft off the coast, and spawning populations were found among the tributaries at a maximum of about 100 miles inland.
- Herring like fish
- Alewife
- Can be invasive but we didn’t realize until mid 20th century
- Native range was clear until recently
- Knew it was atlantic drainage but how far west we were not sure
- Nat range = includes lake Ontario
- This sp was able to get into the rest of the great lakes with welland canal bypassing niagra falls (natural barrier) along with lamprey
- And it just exploded in these other lakes
- Green line east – now native range
- Red = non native range
- Not 100% not native to great lakes bc it is probably native to lake Ontario
- Eastern rivers all the way west to lake Ontario = nat range bc niagra was a barrier
- SO technically native to part of the great lakes but not all
- Spatial reference is important
- Doesn’t mean it is not less of a problem though
- Natural dispersal barrier = Niagara Falls;
10
Q
Explain the occurrence of natural invasions on human time scales and the spatial scales they happen in
A
- they are rare on human time scales
- usually occur over small spatial scales
- VS human assisted invasions which occur in higher freq over larger spatial scales
11
Q
How do natural invasions occur?
A
- creation of dispersal corridors ex through glacial retreat, continental drift or chance events to bypass a geographic barrier
- the removal of a physiological barrier e.g. a thermal barrier shifting over time
12
Q
Explain natural invasion of opossum shrimp (Mysis relicta)
A
- original natural range was in around quebec, ontario up into NWT
- Wisconsin ice maximum moved them out to Kootenay lake and Waterton lake – two places that previously they would have had no way to get to.
- Glacial melt water allowed opossum shrimp to expand their range and due to glacial retreat, they were refugees in the areas they were stranded.
- Distribution reflects the boundary line of the glacial retreat
- Planktonic shrimp
- Adapt for cold water
- Occurs outside of green line bc we moved it bc we thought fish would like to eat it
- We have a natural range reflecting dispersal range in evo past from glacial melt water and retreat for dispersal and adaptation
- We have a distribution outside of it due to human interference
13
Q
Collared dove?
A
- expanded it’s range across Europe, naturally
- it’s not a migratory bird
- it is strongly dispersive
- Successful natural invader
- Historically confined to turkey and central asia
- It took off from there
- Spread in early 1900s
- NW across Europe and invaded UK
- Last ten years it spread across the atlantic and reached western Canada
- Completely on its own
- Driving forces behind it are from human influence
- Changing climate and agriculture increased its success rate
- But its dispersal was via natural mechanisms
14
Q
Examples of natural disasters expanding the range of a sp?
A
- exotic weed
- introduced to a lake by hurricane francis
- floodwater swept weed fragments from one reservoir to the next
- iguanas being dispersed overwater via hurricane. Hurricane luis and Marilyn through lesser Antilles, Caribbean
L> this occurred by floating on debris
15
Q
Describe an example of a prehistoric mass invasion
A
- The Great American Faunal Exchange
- 3 million years ago, N and S America became connected via panamanian land bridge
- mammals moved north ( armadillos, anteaters, opossum, porcupines) and south ( bears, racoons, weasels)
16
Q
What are Wallace’s Biogeographic realms?
A
- Nearctic
- Neotropical
- Ethiopian
- Palaearctic
- Oriental
- Australasian
- broad division of the world’s land masses into realms that organisms have been evolving in relative isolation over long periods of time separated by oceans, deserts, mountains etc making barriers of migration
- these realms are characterized by the evolutionary history of the organisms they contain
- Each continent has it’s own characteristic flora and fauna reflecting unique evol opportunities. Evolving in relative isolation allowing distinctive flora and fauna. Barriers preventing/limiting genetic material exchanging across the barriers ; reproductive isolation
- THIS all changed 1000 years ago through colonialism
- We’ve eroded the distinctiveness in these regions
