the new habitization of organisms mediated by human transportation
how do new species typically arise (2)?
via isolation1. allopatric speciation caused by physical geographic barriers2. sympatric speciation caused by reproductive isolation (same area)
True or False: species cannot naturally expand their geographic regions (w/o) human interference
False; species can naturally expand their geographic region without human interaction - however that is not our main focus
why is the impact of humans considered in the definition of "invasive" or non-native species?
humans have helped overcome physical barriers for species via transportation or have aided in their migration for agricultural or domestication purposes
impact of colonizers and immigrants on the growth of invasive species?
as these groups travel across land, water, islands, continents they bring with them new organisms (plants, animals, microorganisms) whether purposefully or accidentally
what was "the great american biotic interchange"? would these organisms be considered as invasive?
the physical connection of the North and South American continent via the Panama Isthmus (likely formed by tectonic activity) mammals from NA and reptiles from SA expanded their ranges across the two continents through Panama NO; the mass migration of various species across the Americas can be seen as "natural range expansion" where these organisms became naturalized to new land
direction of homo sapien migration
originated in southern and eastern Africa, then traveled to Europe, Asia, and then the Americas
what is the connection between organisms and humans during mass migrations?
organisms may be taken with humans for domesticated or agricultural (seeds/grains) purposes in new settlementsmicroorganisms and pathogens may hitch a ride with unsuspecting organisms (livestock, plants)
human-mediated vs natural range expansion
there is a larger focus (in invasion studies) on human-mediated expansion due to the rate at which new colonization has massively increased due to humansnatural-range expansion is a result of habitat or climate changes in the environment that may cause species to move outside their normal realm (not as quick of an effect)
3 major consequences of invasive species
1. eat, compete, and hybridize with native species 2. loss of ecosystem services (ie. loss of biodiversity can reduce filtration, pollination, decomposition provided by certain ecosystems)3. economic harm (livestock, fisheries, etc. leads to profit/resource loss)
why do invasive species typically have a negative connotation?
from an ecological or economic standpoint; invasive species are often associated with loss/destruction or for its negative impacts on either factor
who was the father of invasion ecology and what was his contribution?
Charles Elton (1900-91)he published The Ecology of Invasions by Animals and Plants in 1958 (1st foundational text highlighting the consequences of moving organisms outside of their natural sphere)he was the first to recognize the threats of invaders
when did awareness for invasive species increase? what is evidence in support of this?
later 90's - early 2000's ; the cumulative and annual number of citations for Elton's publication of The Ecology of Invasions by Animals and Plants increased exponentially
what are 3 reasons for the spike in interest in invasive species?
1. lag time exists, it takes time to see the impact on ecology and the environment2. increase over time in the amount of export/imports and travel globally 3. biologists/ecologists often cannot perform normal studies without running into invasive species (hard to ignore)
invasion ecology grew out of a variety of older research on ...
agriculture, forestry, entomology, zoology, botany etc.
what were some causes to change terminology regarding invasion ecology? what neutral term did professionals settle on?
political and social stigma (ie. invasive- war, exotic- racist)"non-native
definition of non-native
species that have been introduced outside of their native range via human actions (even if they are still within their native continent) *not taking into account impact
definition of invasive
species that 1. have a negative ecological or economical impact (dependent on human perception)2. are self-sustaining and spreading aggressively into new environments (not always impactful or harmful)
House Finches
original range prior to the 1940s were on the western coast of the USintroduced in the 1940s to eastern US (Long Island, NY)-law stated pet shops in NY couldn't sell them anymore, so finches were released into the wildpost-1940s finches have since spread across the eastern US
True or False: Invasion is an event
FALSE; it is a process (a min. of 3 stages: pickup > transfer by humans> release into the wild)
what are the 4-5 stages of invasion?
1. pickup2. transport3. (release into wild) -> establishment4. spread5. impact
True or False: some organisms may be able to skip steps in the invasion process, but it is not common
TRUE; some organisms may retain the ability to skip steps early on if they are able to overcome barriers such as captivity/cultivation (introduction); however survival rates are between 5-20% during the transportation stage
6 barriers non-natives face during the invasion process (and what stage of the process they affect)
1. geographic barriers (transport)2. cultivation/captivity (release/introduction)3. survival (establishment)4. reproduction (establishment)5. dispersal (spread)6. environmental (spread)
what is a common misnomer of the term "invasive"?
labeling an entire species as invasive ;some species can be invasive in some places but not others (only members of a species should be deemed invasive if causing harm)
do species traits (1) or community properties (2) determine the success of an invader?
bothif the inherent traits of a species are useful in the new environment then either case could be madeex. Burmese pythons in the Everglades (adapted to tropical climate in SE Asia, similar climate in Florida)
Brown Tree Snake (case study)
- found in other islands of Micronesia (ie., New Guinea) - transported to Guam during WWII during US Navy staging efforts between islands to transport supplies, vehicles and equipment from New Guinea and Australasia - introduced the brown tree snake to Apra Harbor in 1945... occupied all of Guam. by 1970- no native snakes or predators on Guam to keep growing population under control -> major loss of birds, reptiles in Guam - brown tree snakes occupy dense city regions as well
definition of a vector
the manner or way in which species are carried - physical method- ie. ship, airplane, train
definition of a pathway
the route between the source and location of release-geographic route from source to release
vectors and pathways are often shaped by ...
the ease of human transport
Triangular Trade Route
1800sThree-sided trade route among England, Africa, and the North American colonies; included the slave trade.trade-winds dictated most efficient pathway, vectors = ships
How are changes in vector pathways influenced by specifics in time period?
compared to ships using trade wind routes in 1800sduring Industrial Revolution (1850s)- increased use of steamboats and planes helped diverge from use trade wind routeschanges in technology influence use of specific pathways (wax and wane in importance due to changes in commercial trade patterns or in the technological innovations of transport vectors)
another term (2) for natural expansion
range expansion or extra-range expansion
example of natural range expansion
Inca Dovenative to Central Americamoved upward to southern USA due to warming climate
2 Categories to qualitatively differentiate natural vs human-mediated extra range dispersal:
1. rate of dispersal (if governed by natural vs human-mediated mechanisms)2. type of dispersal (referring to geographic origin and scale)
Dispersal Rate in Human-Mediated vs Natural Dispersal and examples (2)
human-mediated dispersal is far faster than natural dispersal 1. Hawaiian plants: island is isolated, post-polynesian and european expansion imports increased and new spp. introduced2. insects from Gough Island was devoid of insect life, w/ settlements insects were introduced
human-mediated vs natural rate of dispersal (successful events/yrs)
natural rate = 1 per 100,000 yearsvia human vectors = 1 per 22-200 yrs
6 Modes of Dispersal
1. Leading-edge dispersal2. Corridor3. Jump dispersal4. Extreme long distance dispersal5. Mass dispersal 6. Cultivation
Leading-edge dispersal
a gradual change in range is initiated by individuals colonizing new areas from the edge of the range *no particular barrier exists that separates 2 geographic regions
Corridor
a physical connection of suitable habitat forms, linking a portion of the original range to another area*passageway opens up between 2 geographic regions
Jump dispersal
propagules disperse over sometimes substantial distances, but still with a connection between the new and original ranges
Extreme-long distance dispersal
propagules move far beyond the dispersal range seen over ecological time scales*seen mostly with human-mediated transport*spp. move beyond natural capabilities
Mass dispersal
a dispersal route that is established such that many individuals can move from different parts of the range to many new sites*think natural disaster, drought, major habitat change
Cultivation
propagules are actively moved and provided with resources to establish and persist*moved to captive environment (zoo, research lab, rescue site)
2 ways modes of dispersal differ in human-mediated transport from natural dispersal
1. new individuals are usually deposited multiple times -think cargo drop offs @ harbors w/ global exports every day-human med. events have frequency to them2. Introduced individuals usually come from several source populations -think Burmese pythons from dozens of source locations in SE Asia
effect of human-mediated transported spp. on genetic variation
human-mediated transport boosts the level on genetic variation
2 main categories of Human-mediated transport
1. commerce in living organisms (intentional)2. transportation related movements (unintentional)
5 Transport Vectors of Intentional/Commerce in Living Organisms
1. food related2. non-food3. aesthetics and pets4. biocontrol5. scientific research or conservation
people have been moving plants and animals since __________
8000 BCE-horses, animal fur/skin, honey, fruits, textiles, gold/silver, slaves, silk, dyes, tea, porcelain, spices, medicine, ivory, weapons
Food-Related (intentional transport)and some examples
mostly fruits, vegetables, spices, meat, dairy to places that need or want them -cows from SE Asia/India-tomatoes from South America-honey bees and chickens from Asia-potatoes from South America
Non-Food (intentional transport)and examples (2)
game species for recreation (and bait)- rainbow trout: transported globally for game in cold water creek fishingserve as biofuel crops-ex: corn
Aesthetics and Pets (intentional transport)examples and issues
horticultural plants (native to Asia) and exotic pets -kudzu, fish , reptiles, amphibians-issue when released from captivity because organisms can naturalize and spread
est. _____ ________ live animals were transported between 2000-2006
1.5 billion
trend of wildlife shipments and individuals imported into the US between 2000-2006
shipments have increased (in the 1000s) , specimens have increased by remain relatively stable and proportional with # of shipments (millions)
what is the majority percent of live organisms identified to on the taxonomic level ?
class (52%)*species (13%)
Biocontrol (intentional transport)and examples (3)
insect predators, parasites, or pathogens (majority have a low success rate for establishment)*soln: introduce sterile organisms to avoid reproduction and spread-Western mosquito fish: to control mosquito pops., in broad range they overpop. due to high fecundity-Cane toad: predatory amphibian, eats a lot, toxic defense, introduced to hawaii sugarcane fields to eat insects, harm dingos too-Mongoose: introduced to kill snakes, eats native birds
Scientific Research or Conservation (intentional transport)and example
plants and animals brought to botanical gardens, wildlife preserves, zoossometimes involved endangered species -Pecos pupfish: native to SW USA/ E MEX Pecos river watershed
Unintentional Transport occurs ...
on or within non-native species (parasites, bacteria, fungus, hitchhike on or inside organisms) within cargo, wheel wells, ship ballasts
how do non-native spp. get transported in ship ballasts?
since ballasts are mostly hollow, they suck in hundreds/thousands of gallons of water (poss. including organisms) before leaving the portat arrival they dump out the water (and possible sucked in organisms) at the new port location
90% of all global trade involves _____ transport
sea
approximately how many species can be transported on one ship?
~10,000takes a little over a week to make the journey
how does unintentional transport rival intentional transport?
unintentional transport is likely carrying more spp. unintentionally than intentional transport (not accounted for)
Zebra Mussel
an example of an unintentional transport small freshwater bivalve mollusk with zigzag markings on the shell, sometimes becoming a pest because it blocks water pipesmore fecund than most bivalveshave free swimming larvae than attach to surfaces causes billions of dollars in damage/prevention
Unintentional Transport and Hitchhikers in Commercial Projects
include ticks, larvae, parasites, intestinal wormsinsects and larvae typically hitchhike on produce from tropical locationscan be on or inside intentionally transported organisms
relationship between GDP and the number of alien plant richness
as GDP increases, the number of alien plants increase (think: increased levels of imports/exports)poorer countries with lower GDPs have less of a chance for invasions due to inability to participate in grand scale trade
islands vs continents/mainlands in correlation between GDP and alien plant richness
islands with similar GDP as continents or mainlands have a higher number of alien spp. due to their increased need for imports as an isolated area of land (limited resources)
relationship between species transport and vector groups: global marine organisms and US aquatic invertebrates
transportation related (unintentional)likely move via ships, ballast water
relationship between species transport and vector groups: US freshwater fish and California freshwater fish
food related and game species moved for food or recreational purposes (fishing)
relationship between species transport and vector groups: US amphibians and reptiles
non-food relatedexotic pets
relationship between species transport and vector groups: Global birds
transportation related unintentional
relationship between species transport and vector groups: Australia birds
unknown (may travel with ships, escape capvtivity)
relationship between species transport and vector groups: European flora
non-food related (aesthetics)
2 determining factors of the strength (dynamics) of a transport pathway
1. number of species moved (over a fixed period of time)2. viability of moved individuals (condition of health determines spread/establishment success)
stronger pathways lead to ...
more establishment of non-native populations
trends in global "dry bulk" vs "oil and oil products" shipping cargo vs air freight from 1970-2005
exponential increase in dry bulk cargo and gradual increase in oil/petroleum (recovery since '85 oil crisis)even more of exponential increase in air freight since 1975
comparison between sea routes in 1880's and air traffic in the 21st century
in 1880's - under 100 trade routesnow- over 58,00 known air flight paths
what is needed to fill in the gap of knowledge regarding invasion rates through time?
time (when) and numbers (of new species) introduced how many? what speed?
Two main patterns in the rate of invasions over time (what is known):
1. records of non-natives at locations have increased over time2. due to random and specific trends in how and why species are transported
summary of data collected by Cohen and Carlton (1998) regarding cumulative numbers of non-native species established in the San Francisco Bay estuary
gradual increases in the number of exotic new species since 1850drastic acceleration around 1980
summary of data collected by Lambdom et al. (2008) about the cumulative number of plants introduced to Europe since 1500
substantial/exponential increase of new species brought in around 1800 during the industrial revolution (steam engine... transportation)
summary of data collected by Hulme (2009) regarding the rate of establishment of no-native taxa per year to Europe since 1500 (plants, mammals, inverts) -why has the invasion rate of plants and mammals flatlined?
introductions of plants and mammals in the 1850's increased... began to flatline in later 20th century due to maxed out number of new species that could be introducedrates of inverts surpasses plants and mammals in 1975-2000 ; possibly due to ballast water unintentional transportation with improvement to sea travel
relationship between vector pathway strength and trends in time for different taxa
demand for taxa (ie. birds, mammals, fish, marine fish, plants, reptiles, etc) throughout time affects the need for transportation of these organismsdependent on the time period are modes of transportation that are most relevant .. which in turn affects changes in importance of specific pathways ex: fur trade less popular in 21st century due to conservation efforts so the fur trade pathway has become weak over time (less quantity)ex: with increasing amount of sea trade in the 1900's transportation of marine life via ballast water has become a stronger pathway
should we expect invasion rates to always increase after a transport pathway has been establish?
eventually the accumulation of non-native species should decelerate although the collection of organisms moved and present will increase but eventually plateau (all that can be brought over will be brought over... not much new left to be transported)
What is the relationship between US imports and the accumulation of invasive species since 1920?
first- exponential increase in new non-natives introducedthen- slowed acceleration of new species introduced and rate nears zero (not many new species left to be introduced)
relationship between lag events and invasion debt
invasion debt is the owed consequence of actions in the far futurebecause establishment of new non-native species may take a long time (50+ years), it may take an equivalent amount of time to see the effect of the future presence of non-native species that were once brought to new area
summary of figure showing alien-species richness of q0 different taxa explained by current and historical socioeconomic models (1900s vs 2000s)
with taxa such as plants, bryophytes, mammals, amphibians fish, aquatic inverts etc. that were brought in (intentional / unintentionally) in the early 1900's, appear to be more established and dominant in sampling results whereas reptiles and terrestrial insects (that were not introduced to commerce/ not in demand as exotic pets) in the early 1900's are represented by socioeconomic models from more recents times (due to lack of introduction many years ago)
Do patterns exist in the biogeography of non-native species?
yes, you can consider latitude, OLD vs NEW world sites, and ecological aspects (competition, habitat availability, sampling effort)
what does invasible mean?
description of how many non-native species a specific habitat can hold or harbor
geographic patterns in the number of invaders (pertaining to distribution of european alien plant species) : industrial vs arable land/gardens/parks vs grasslands etc.
trend follows that areas under anthropogenic influence present more opportunities for invasions due to areas of disturbance opening up habitats for establishment- industrial !!!- arable land, gardens, parks !!-grasslands !whereas more natural and less disturbed grounds show a decrease in non-native establishments -coastal, sparsely vegetated, woodland, mires/bogs
Geographic patterns in numbers of invaders: 3 largest patterns most noted
1. larger numbers of non-natives found on islands compared to mainland areas of equal size (import)2. temperate ecosystems tend to have more non-natives than tropical systems3. higher number of non-natives in the New world (Americas) vs the Old world (Europe, Africa, Asia)
Geographic patterns in numbers of invaders: anthropogenic effects
trade, travel, industry
Geographic patterns in numbers of invaders: Ecological effects (specifically an Island)
islands favor for non-native species (less likely to harbor natural predators) (less species than continents - more room for new species to reside in available niches)
Geographic patterns in numbers of invaders: effects of latitude (Tropic of Cancer)
more non-natives reside above the Tropic of Cancernorthern distribution could be due to...- more competition in tropical areas- northern hemisphere more heavily populated (more anthropogenic influence) - lack of many non-natives found could correlate to lack of search effort
Geographic patterns in numbers of invaders: association with temp and water
organisms may tolerate mesophilic environments
Geographic patterns in numbers of invaders: Old vs New WorldCalifornia vs Mediterranean debate (why are there more non-natives in CA if climates are similar?)
a) lack of movement in one direction -migration typically is one way (more movement of Old world species to New world locations, less exports)b) less ecological interference - New world is more invasible due to constant introductions of new species-anthropogenic effects allow for more invaders to establish
What are propagules?
the set of individuals released into the non-native environment
propagule size vs propagule number
propagule size: number of individuals releasedpropagule number: number of release events
propagule pressure
equivalent to establishment success; is measured by the number of individuals being introduced via multiple introduction eventspropagule size + numberhigh pressure increases the chances of establishment
propagule composition (4 factors that can influence establishment success)
healthagesex ratiosphenotypes
propagule composition: HEALTH
condition of propagule influence ability to spread and establish
propagule composition: AGE
too young- haven't reached reproductive maturity too old- lowers survival rate, fewer years left to contribute to maturity
propagule composition: SEX RATIOS
reproduction is influenced by male:female ratios and contribute to future spread and establishment
propagule composition: PHENOTYPES
variation increases adaptations to specific/native range if mismatched ... lowers success within the new environment
2 types of environmental conditions (factors)
abiotic (non living) biotic (living / ecological forces)
donor vs recipient region
donor region: location of originrecipient region: place of propagule release** look for how the two locations are similar (propagule "match" for success) OR are dissimilar (not a good "match", decreases chance of survival)
relationship between donor/recipient region and propagule pressure
basic physiological requirements must be met certain species cannot survive accommodating to the recipient region because they are not adapted to it the condition of individuals can vary across geographic range(ie., freshwater bass cannot acclimate to a marine/salt water environment) (ie., tropic orchids that require high humidities cannot survive the desert environment)
what is the correlation between proximity to the recipient region and propagule success?
the closer a propagule's donor region is to the recipient region... there is less duration of transport and distance... thus increasing chances of survivalthe further the transport of a propagule and the longer it takes to be released to the recipient region... there is a higher chance of the deterioration in health or even death of the propagule (decreasing survivorship)
Case study: Ballast water
relative density of propagules decrease as the length of days since ballasting increaserelative density of propagules surviving length of time on ship also increase/remain steady if being transported near the cargo hold (steady temp close to water) compared to the fluctuating temp/light experienced near the deck tanks
Establishment curves help...
how to predict success of establishmentit is like a probability chartaccounts for age, sex ration, propagule size and number, behavior/traits/adaptations which all contribute to propagule pressure
How does the number of propagules affect establishment success?
larger population size decreases the chance of extinction (more resilient)larger populations can better absorb sudden drops in survival or birth rates (ie., due to environmental stochasticity) The higher propagule size, the more likely the founding population can withstand shock
How does behavior of propagules affect establishment success? (include Allee effect)
some animals confer advantages related to behavior or other group dynamics (lower % of survival if propagule is taken out of group setting)predator defense (more eyes and ears)Allee effect: a reduction in the per capita population growth at low population density (require larger number/ groups for survival)
Allee Effect (definition and 3 disadvantages)
a reduction in the per capita population growth at low population density due to ...1. failure to find mates2. harder to hunt/find food3. attract pollinatorscan be a big disadvantage for some organisms
Difference in the chance of invasion success within populations with Allee effects vs no Allee effects
with Allee effects: if there was no immigration, the propagules will take longer to develop and establish invasion success, they require more individuals to establish reproductive success unless the immigration rate is higherwithout Allee effects: chances of success increase quickly (almost independent of immigration rate, but a higher immigration rate will further increase initial success ... until plateauing)
identity of individuals (and their contribution to invasion success)
unique individuals and their fitness help gauge probability for establishment success (look at adaptations, influence of individual fitness on population growth)
propagule size vs productive success
a simple count of propagules may not be sufficient enough to determine success (although it does contribute) need to look at reproductive fitness of individual members by considering: fecundity, distribution of age/ reproductive maturity, maturation rate, adaptations to increase reproductive viability (ex: ciclid- edible slime secretion to feed offspring)
age distribution
the proportion of each age group represented in the total population use Life history (refers to the pattern of survival and reproduction events during the life of an organism)- R vs K species
R vs K selected species
R selected species:-rapid growth-good dispersal-short lifespan (low survivorship, high fecundity)-rarely maintain stable population (ie rarely reach K)-influenced by density independent factorsK selected species:-K refers to carrying capacity-Slow growth-long lifespan (high survivorship, low fecundity)-more likely to maintain K-influenced by density dependent factors
as propagation pressure increases, chances of establishment ...
increases
limitations of using historical invasions to tie propagulge pressure to establishment success?
difficult to find credible information on number of individuals and release eventsbest evidence comes from intentional releases of game or species used for biocontrol
Canadian biocontrol Case Study (1975) PurposeSuccess vs Failure Analysis (propagule size and number)
Estimated 90% of insect introductions between 1880-1970. Wanted to understand why so many insects released for biocontrol fail to establish.of 159 species introduced; 115 FAILED and 44 SUCCEEDEDPropagule Size Effect: - median propagule size across 159 events = 5000- median propagule size across 44 successful events = 31,200 (INCR. PROP SIZE -> INC. EST. SUCCESS)Propagule Number Effect: - 70% of species released >20 times established successfully- 10% of species released <10 times established successfully
How can you use your knowledge of Propagule Number on biocontrol/invasion prevention to stop later establishment success?
could prevent future establishments if transfer of organisms/species are stopped early on (I.e. by 20th introduction.... species are likely to have established and become self sustaining)
New Zealand Birds Case Study (source data from 1922, 3 papers)PurposeSuccess vs Failure Analysis (propagule size and number)
wanted to find relationship between propagule size, number and establishment success of 133 bird species released in NZ.- only 6% of species with <10 released individuals were successful (LOW propagule size)- 83% of species with >100 released individuals established (HIGH propagule size -> easier to find one another to reproduce, community effort)
How does propagule pressure interplay with other ecological mechanisms to influence invasion success? (2 variables)
1. Life History- high fecundity, lifespan, age at release2. Biotic Resistance- range of release (microhabitats and niche availability)
the hidden influence of Propagule Pressure on Life History (as an ecological mechanism influencing invasion success)
Casey et al. 2004 sorted through available data on propagule sizes of bird introductions, combined this data with other variables purported to increase establishment success propagule size is HIGHLY correlated with many other explanatory variables (ie., body mass, geographical range, annual fecundity, island or mainland, diet) -the principle determinant of successful establishment was propagule size -conclusion: propagule pressure was a good predictor on establishment success**studies that have shown correlation between these variables and establishment success may simply be reflecting the hidden effect of propagule size
the hidden influence of propagule pressure on Biotic & Abiotic Resistance (2 historical explanations)
*there is a confusing difference in the numbers of non-native across different community types. need to look at how occupied or disturbed are these natural habitats to see how this affects "invasibility"1. Native Species Richness (ties into competition)2. Habitat Disturbance Levels
What is another (not biotic/abiotic related) explanation for the confusing differences in the numbers of non-natives across different community types? (regarding propagule pressure)
possibly just the result of variation in propagule pressures across communitiescommunities with MANY invaders are simply those that have had MANY individuals of SEVERAL species released
trend between the probability of community invasion with increasing abiotic and biotic resistance (in high, medium, and low propagule supply)
all 3 groups have high probability of community invasion success with LOW abiotic/biotic resistance levels (transitory zone- begin to decrease non-linearly)- high propagule supply can help DELAY the effects of resistance longer than medium and low propagule supplies (takes higher resistance levels to begin exponential decrease)- medium propagule supply is between high and low-low propagule supply is most susceptible to Increases in resistance; begins to decline at much lower levels of resistance
direction of movement (pre- vs post- invasion) with regards to the history of invasions on the probability of community invasion with increasing abiotic/biotic resistance
GRAPH SHIFTS LEFT- can potentially delay effects of increasing resistance if individuals were pre-established prior to new drop offs (increasing # of individuals can increase chances of establishment success0- changes in the environment by previously settled species can make environment better suit the needs of invaders- Allee effects... larger population size helps with establishment success (lower number = more susceptible)
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