Biological Invasion

1. ECOLOGYAND ECOSYSTEMS
ASSIGNMENT WORK
BIOLOGICAL
INVASIONS
Submitted to :
Dr Sandeep Kaushik
Department of EVS
Submitted by :
SHIVAM SONU
BSc – EVS (IIIrd Sem)
2019-20
INDIRA GANDHI NATIONAL TRIBAL UNIVERSITY, AMARKANATAK

2. CONTENT
1. Definition of Biological Invasion
2. Concept of exotics and invasive species
3. Invasive Species Spread
4. Characteristics of invaders
5. Stage of invasion
6. Mechanism of invasion
7. Invasive pathways
8. Impacts of invasion on ecosystem and communities

4. BIOLOGICAL INVASION

5. INVASIVE SPECIES
An invasive species can be any kind of living organism—an
amphibian (like the cane toad), plant, insect, fish, fungus,
bacteria, or even an organism’s seeds or eggs—that is not
native to an ecosystem and causes harm. They can harm the
environment, the economy, or even human health. Species
that grow and reproduce quickly, and spread aggressively,
with potential to cause harm, are given the label “invasive.”

6. Invasive species are among the leading threats to native wildlife.
Approximately 42 percent of threatened or endangered species are at risk due
to invasive species.
Human health and economies are also at risk from invasive species. The
impacts of invasive species on our natural ecosystems and economy cost
billions of dollars each year. Many of our commercial, agricultural, and
recreational activities depend on healthy native ecosystems.
An invasive species does not have to come from another country. For
example, lake trout are native to the Great Lakes, but are considered to be an
invasive species in Yellowstone Lake in Wyoming because they compete with
native cutthroat trout for habitat.

7. CONCEPT OF EXOTICS SPECIES
Exotic = Foreign
Or
Also called as Alien species.
Defination :Invasive alien species (IAS) are species whose introduction
and/or spread outside their natural past or present distribution threatens
biological diversity.
IAS occur in all taxonomic groups, including animals, plants, fungi and
microorganisms, and can affect all types of ecosystems. While a small
percentage of organisms transported to new environments become invasive, the
negative impacts can be extensive and over time, these additions become
substantial.

8. EXAMPLES OF INVASIVE SPECIES
 Cogon Grass is an
Asian plant that arrived in
the United States as
seeds in packing
material. It is now
spreading through the
Southeast, displacing
native plants. It provides
no food value for native
wildlife, and increases
the threat of wildfire as it
burns hotter and faster
than native grasses.

9.  Feral pigs will eat
almost anything,
including native
birds. They compete
with native wildlife
for food sources
such as acorns.
Feral pigs spread
diseases, such as
brucellosis, to
people and
livestock. E.
coli from their feces
was implicated in
the E.
coli contamination of
baby spinach in
2006.

10.  European green
crabs found their
way into the San
Francisco Bay
area in 1989. They
outcompete native
species for food
and habitat and
eat huge quantities
of native shellfish,
threatening
commercial
fisheries.

11.  Water hyacinth is a
beautiful aquatic
plant, introduced to
the U.S. from South
America as an
ornamental. In the
wild, it forms dense
mats, reducing
sunlight for
submerged plants
and aquatic
organisms,
crowding out native
aquatic plants, and
clogging waterways
and intake pipes.

12. CHARACTERISTICS OF INVADERS
The characteristics of invading species were explored using
the Ecological Flora Database, and by using comparisons
available in other studies. Invasion success has been related
to both abundance and distribution in the native range, which
are themselves related. Abundance is probably the key
variable. In the British flora invading species are characterized
more by their distribution and morphology than by their life
history and reproductive behaviour. The size of the plant and
characters related to propagule pressure created by humans
come out as important correlates of success. For biological
characters, genetic studies and the phenomenon of boom-
and-bust both suggest that the critical interaction between
species and habitat is often subtle. Nevertheless, studies on
pines and squirrels show that such important biological
characters can be determined.

13. STAGE OF INVASION
An invasive species is defined as a non-native species to an ecosystem
whose introduction causes economical, medical, and/or environmental
harm. Invasive species can include plants, animals, and microbes.
1. The first of stage of invasion, introduction involves the movement of a
species into a non-native area; human transport is the most dominate form of
invasive species introduction. Humans have the capability to move species to
places that would be otherwise inaccessible for species. People may
introduce a species intentionally or accidentally. An intentional pathway can
only be judged by the impacts of the organism. Some accidentalpathways
include ballast water discharge, importation of resources, and the immigration
of people. However, species may invade through natural pathways like wind
and water currents.
2. The second stage of invasion, colonization is the initial interaction
between the invasive species and the habitat. Whether or not the species
survives is up to the species persistence and chance. Sometimes, successful
colonization involves repeated introductions to overcome natural and human
boundaries

14. 3. The third stage of invasion, establishment means the species
successfully colonized into the environment and is able to reproduce.
The first three stages usually requires human intervention but after
the species disperses into the environment the species no longer
needs assistance.
4. The fourth stages of invasion is the dispersal of the new species
and formation of populations across the environment. The United
States Department of Agriculture offers detailed information on
invasive species at the National Invasive Species Information

16. MECHANISM OF INVASION
The mechanisms of invasion of a parasite into host tissue or host cells. Single cell
protozoan parasites evade the host immune response by residing within host cells and
enter the host cell with minimal trauma to ensure that they preserve an environment
suitable for their replication and do not trigger a lethal host immune response. This
intracellular invasion paradigm is also shared by a helminth parasite, Trichinella
spiralis. Often an invasive larval form penetrates skin or the mucosa of the
gastrointestinal tract to enter into the host.. The chapter states that the invasion
phenomenon itself can be divided into three successive steps: recognition and
attachment, internalization and vacuole development, vacuole maturation. Entamoeba
histolytica, which is a protozoan, does not invade intra cellularly at any stage of its
life cycle unlike other protozoas. The process of its invasion (extracellularly) and its
properties are also elaborated in the chapter. .To complete the invasion process,
helminth parasites have evolved sensory organs for finding and navigating within the
host, attachment mechanisms utilizing specialized mouth structures or glue-like
secretions, and hydrolytic enzymes to digest macromolecular barriers in the
extracellular space

17. INVASIVE PATHWAYS
Pathways are the means and routes by which invasive
species are introduced into new environments. Pathways can
generally be classified as either natural or man-made.
Natural pathways (i.e., those not aided by humans) include
wind, currents (including marine debris), and other forms of
natural dispersal that can bring species to a new habitat.
Man-made (or human-mediated) pathways are those which
are created or enhanced by human activity. These are
characteristically of two types:
a). Intentional
b). Unintentional

18.  Intentional, which is the result of a deliberate movement of a species by
humans outside of its natural range. Examples include the introduction of
biological control organisms or the movement of species for the horticultural
or pet trade. Intentional introductions as a whole should not be labeled as
either good or bad. A specific intentional pathway can only be judged by the
positive or negative impact of the specific organisms that are moving along
that means.
 Unintentional, which is the inadvertent movement of species as a byproduct
of some other human activity. Examples of unintentional pathways are ballast
water discharge (e.g. red-tide organisms), pests and diseases in imported
plants, firewood, and other agricultural products (e.g. fire ants), the
movement of recreational watercraft (e.g. zebra mussels), and the
international movement of people (e.g. pathogens). In these and countless
other unintentional pathways, the movement of non-native species is an
indirect byproduct of human activities.

19. Examples of ways invasive species spread include:
 Agricultural materials
 Aquaculture farming
 Ballast water and shipping
 Classroom or science lab (escapes or introductions)
 Firewood
 Fishing gear
 Food trade and its packing material
 Fouled hulls of commercial and recreational vessels
 Internet sales
 Moving
 Outdoor gear (hitchhikers on boots, clothes, and camping
equipment)
 Passenger baggage
 Pets (unwanted or escaped)
 Plants and plant parts (escaped or disposals)
 Recreational boats
 Recreational vehicles (RVs)

20. IMPACTS OF INVASION ON ECOSYSTEM AND
COMMUNITIES

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