Invasion Bio Final

Non-native

A species that has been outside their normal geographic ranges via human actions, regardless of their eventual impact on native ecosystems

Inavsive

A species or population that has a clear ecological and/or economic impact, or that is spreading aggressively

Stages of the Invasion Process

• transport (geography)

• introduction (captivity/cultivation)

• establishment (survival, reproduction)

• spread (dispersal, environment)

• impact

transport vector

the manner by which a non-native species is transported along a pathway

transport pathway

the route between the source region and release location

Strength of a transport pathway

the number of species moved and the viability of the individuals moved, upon release

Range

the geographical area where that species is (can be) found

Range limits

expression of a species’ ecological niche in space

disperal

an individual-level behavior that refers to movements that (have the potential to) result in gene flow within and between populations

extra-range dispersal

the movement of individuals from a species’ current range to a new range

acclimatization societies

groups of (often wealthy) citizens whose goal was to import species into their home country to “enrich” their surroundings. Popular at the end of the 19th century.

invasibility (informal definition)

the susceptibility of a given location/habitat/place to non-natives becoming established

propagule

set of individuals released in a non-native environment

propagule size

the number of individuals released in a single introduction event

propagule number

the number of times a species is introduced to a new location

propagule pressure

measure of the number of individuals (size) and the frequency of introduction events (number) of a species into a new area

propagule composition

the diversity, types, and quality of organisms (e.g., seeds, fragments, spores, gametes) forming a new population

propagule bias

non-random selection of individuals transported and released (propagule), which can cause wrong conclusions on which traits affect establishment

allee effect

reduction in the per capita population growth rate at low population density

abiotic/biotic resistance

hypothesis that aspects of the environment (abiotic) or the local community of organisms (biotic) limit the establishment and spread of invasive species

disturbance

any relatively discrete event in time that disrupts the ecosystem, community or population structure and changes resources, substrate availability, or the physical environment

EICA (evolution of increased competitive ability) hypothesis

species reallocate defensive energy towards other fitness-increasing traits

detection threshold

population size necessary for a non-native population to be recognized

lag time

the length of time between initial establishment and subsequent spread

range pinning

an (invasive) species in confined to a narrow area due to the inability to reach a high enough population density to produce large propagules and grow in a suboptimal environment

impact

a measurable change to the properties of an ecosystem by an established non-native species

homogenization

increased similarity in fauna and flora between previously distinct regions as a result of the loss of endemics and gain of widespread invasive

genetic bottleneck

change in the proportions (and potential loss) of alleles in a population, often after a rapid and drastic reduction of population size

founder effect

loss of alleles that occurs when a new population is established by a small number of individuals from a larger source population

risk

the product of likelihood of an event and its consequences

rapid response

enacting management as soon as a new non-native species is discovered to increase eradication success

assisted migration of rewilding

physical relocation of critically endangered species to a new, permanent location, after the native habitat is threatened by climate change, habitat loss, etc.