Download Ecological Impacts of Invasive Species: Genetic to Landscape and more Slides Biology in PDF only on Docsity! Ecological Impacts of Invasive Species Joshua Dunlap and Jeff Smith Biology Dept., WWU http://100thmeridian.org/Images/zebramussel3.jpg Chapter
9 Ecological
Impacts: •
Genetic •
Individual •
Population •
Community •
Ecosystem •
Landscape,
Regional,
and
Global Genetic
Impacts: Difficult
to
document,
but
profound Alterations
of
Gene
Pools: •
Hybridizing
‐
Sterile
or
not •
Introgression http://www.cala.cc/Mallard-duck.jpg Some
schools
of
thought: •
Invasives
are
preadapted •
Invasiveness
appears
upon
release
of
enemies or •
Invasion
success
is
because
of
hybridization
and
introgression Competition: Increased
when
narrow
niches
are
natural
or created
by
encroaching
human
activities. http://www.centerforplantconservation.org/ProfileImages/access/7632a.jpghttp://www.wildflowersmich.org/assets/images/spotted_knapweed.jpg Knapweed VS Rockcress Predation: •
Frequently
discussed ‐
Easy
to
observe
and
quantify •
Possible
devastating
effects
in
systems •
May
bring
about
Allee
effects http://www.flickr.com/photos/chrisvanwyksadventures/2236572216/ Physical
Impacts: Formidable
population‐level
consequences can
come
from
physical
attributes
of
the invader. •
Zebra
mussels
ability
to
physically overgrow
natives Endemic
blue‐tailed day‐gecko
is
the
sole pollinator
and
seed disperser
of
the critically
endangerd endemic
plant
Roussea simplex. Hansen and Mueller (2009): http://photos.mongabay.com/07/0417gecko.jpg http://photos.mongabay.com/07/0417gecko.jpg The flowers and fruit are often visited by the invasive ant Technomyrmex albipes. The geckos avoid foraging on plants occupied by the ants. http://keys.lucidcentral.org/keys/v3/PIAkey/Images/lucid%20live%2 0photos%20(FULL)/Technomyrmex_albipes_w_CASENT0171130 _H.jpg Text: Community Impacts Impact of invasive species the entire organismal assemblage of a given ecosystem Effects felt across different trophic levels Measured in terms of alterations to the said ecosystem Species composition Extinctions Data: Morrison L.W. 2002 Both the number of sp. and individuals of native sp decline drastically at time of invasion However by 1999 both measures back to pre-invasion levels Data: Morrison L.W. 2002 Same pattern seen for non-ant arthropods Why the rebound? Text: Ecosystem Impacts Impact on the organismal community AND the abiotic environment/ecological processes) Alteration of nutrient availability/cycling Water availability Soil pH, salinity, erosion… Fire frequency etc Text: Ecosystem Impacts: Examples Cheatgrass increases frequency of fires Zebra Mussels depleting N, K availability Salt Cedar increase soil salinity, while reducing water availability http://www.soonerfire.org/images/grass_fire.jpg Journal Article Effects of Invasive, Non-Indigenous Plant Species on Ecosystem Processes: Lessons from Florida (Gordon D.R. 1998) Literature review of the ability of invasive species to alter host ecosystems Examined 31 species defined as “most invasive” (but data limited)
