Test 3 Flashcards
Jeschke et al 2020 2 comparisons regarding natural enemy pressure
- looked within communities (pressure of enemies of invasives and native in same community within introduced range)
- biogeographical comparisons (looks at enemy pressure in native AND introduced ranges)
examples of biotic effects of invasions
competition; consumption; genetic hybridization
examples of abiotic effects of invasions
change in resource availability; change frequency/intensity of disturbance; change in physical, biogeochemical structure or function of ecosystem
Extinction debt
time delay between impacts on a species, such as destruction of habitat, and the species’ ultimate disappearance
case study of Lake Victoria
in isolation, >500 spp of cichlid fish evolved with adaptive radiation. After commercial fishing began in 1930s. trawlers were used—causing overfishing that greatly declined native cichlid stock
-1950s -Nile perch was introduced—apex predator in a system that didn’t have one. Took about 20 years for population to suddenly explode in 1970s
-native diversity soon collapsed to 3 dominant cichlid spp in less than 10 yrs—many going completely extinct
-now Lake Victoria is big rich asshole trophy hunting place
—now there are huge algal blooms, detritus, hypoxic/eutrophic conditions—center of lake is more or less completely hypoxic
-Nile perch actually fuels many armed conflicts in surrounding countries—exchanging perch for guns & ammunition
Adaptive Radiation
a single or a few spp give rise to many different spp often with distinct ecological roles as they evolve in isolation to fill niches (ex: Darwin’s finches)
Hybridization
interbreeding between genetically distinct populations—often restricted to interbreeding between spp but subspecific pops may be considered
Introgression
gene flow between populations whose individuals hybridize, where hybrids backcross to one or both parent pops
-oftentimes, one spp is more affected than the other (with invasive impact, native spp genetics typically become less common and more of genome is invasive due to larger pop size)
Hybrid Zones
geographic boundaries where spp may be hybridizing—possibly assimilation of 1 group into the other
ex: tatarian X Morrow’s honeysuckle; purple X native loosestrife; cattail hybridization (invasive X native), etc
Demographic Swamping
where hybrid fitness strongly reduced relative to parent spp (outbreeding depression). If hybrids are common, one or both parental lineages may decline below replacement rate due to wasted reproduction—leads to extinction
Genetic Swamping
if outbreeding depression is less severe, pop growth rates exceed replacement rates, one or both parental lineages replaced by hybrids.
—results form asymmetry of population size and/or one-way gene flow
Cryptic Invasions
describes 2 different processes:
1) cases of mistaken identity. These errors have become less common with genetic testing, but still cases of inv spp comprised of separate spp
2) replacement of native genotype with exotic genotype
ex: interesting case of Phragmites australis (native genome was fairly uncommon spp, but suddenly starting exploding in popularity—now know it’s because of hybridization with non-native)
3-pronged approach for invasion management
1) Prevention (through education, laws & policies, research/risk assessment/monitoring tools) ALWAYS MOST COST-EFFECTIVE
2) Eradication (early detection/rapid response; removing ALL propagules paired with ecosystem restoration)
3) Control (limits the ecological / economic costs below some arbitrary threshold: mechanical / chemical / physical; biological–can be integrated approaches; novel approaches like gene drives, resistance breeding, etc)
Invasion Curves
can show options for 3-pronged management plans well: oftentimes, first detection occurs after the point where eradication is still feasible—time lags, low early detection–some spp are hard to detect early ex: EAB)
“dirty list” or reactive approach to invasive species prioritization
made of spp list that are already established and actively causing issues—all other upcoming exotic spp are permitted “innocent until proven guilty”
-take a long time to get listed
-obviously flawed (only prohibiting things we already know are bad)
“clean list” or proactive approach to invasive species prioritization
all spp are assumed to be potentially invasive unless evidence exists to the contrary “guilty until proven innocent”
-it is more costly, some lost economic opportunity
-lack of info, inadequate mechanisms for testing potential invasiveness, lag times, quarantine conditions, generation time, etc
-enforcement (if agencies like APHIS are chronically underfunded, undermanned)
-weak laws, light punishments
-lobbying groups are well-funded by opposition groups
The Lacey Act of 1900
first broad-based federal law broadly applicable to invasive spp
–although still in force as most important invasive spp law, was not intended for invasive spp at all—but for over-exploitation of wildlife for commercial purposes
Plant Quarantine Act (1912)
gave APHIS authority to regulate importation of nursery stock & plants
Federal Seed Act (1939)
required accurate labeling and purity of imported seeds
Federal Noxious Weed Act (1974)
prohibits importation of any plant that can directly/indirectly injure crops, useful plants, and livestock (including fish & wildlife)
National Invasive Species Act (1996)
specifically for invasives but scope was narrow, encompassed only aquatic spp introduced through ballast discharge
Executive Order 13112 (1999)
—arguably most important legislative initiative on inv spp in US
-conceptualized a comprehensive mgmt. framework for inv spp
-attempts to solve some bureaucratic issues bt different agencies (more collaboration)
-created an advisory committee (Invasive Species Council) to brainstorm more solutions
-Key Focuses of management plan—focusing more on early detection & rapid response
—*weakness of exec orders is they are not codified into law
Plant Protection Act (2000)
-replaces Federal Noxious Weed Act and many other APHIS authority acts (consolidates 10 existing plant protection laws)
-OTA 1993—the Office of Technology Assessment published comprehensive evaluation of economic costs of inv spp
-Fantle-Lepczyk et al (Feb 2022) paper looks at economic costs in modern day
-when cherry trees were gifted to D.C. from Japan, they were infested with insects, so were burned (Charles Marlatt) “Quarantine 37”
—eventually led to this Plant Protection Act
Elements that Laws Need to Be Effective
-Education (public must understand WHY law is in place)
-Compliance (need public buy-in to law—can take effort)
-Enforcement (needs to be consistent and applied)
-Penalty (needs to be imposed and meaningful)
