Exotic species• Exotic species are those species living outside of its native home range.• Many botanist refer to alien or adentive species where as biological invaders introduced species non native species and non indigenous species.•.
So biologist use this term if a species ispresent outside of its natural geographicrange where as non biologist called theexotic species.
How species move ?There are different ways for transfer ofexotic species .Stowaways Subsistence and CommerceRecreationScienceBiological controlHabitat /climate change
StowawaysLarge portions of the species that havetransferred around the world werestowaways.Species that have greatly left behind.Stowaways often go unnoticed becausethey are in very small and inconspicuous.Travelling as eggs, pupa spores on foodor on roots of plants .
Subsistence and CommerceMost deliberate attempts to combine worlds biota have been motivated by our needs for food.Colonist every where have brought theirown domestic plants and animals with themand often sent back new plants and animalsto their home range .
Conti…….. In Europe colonization results intransportation of potatoes, corn went back to oldworld on the same ship that were introducinghorses, wheat and many other species.Species for food dominate the list of plannedintroducing but other needs also haveintroduction.So wild species are important for commercialpurposes.
RecreationSupport hunters and anglers have beenprimary catalyst for planned introduction ofexotic wild species.In California 50 species out of 133 freshwater fishes are not native to state. peopledumped new species of fishes into almostevery water body that they visit regularlyincluding both game fishes and smallerfishes for food and gaming
ScienceTo study closely scientists oftenestablish breeding colonies in theirlaboratories sometime these species areoutside of their native range andsometime they escape.Example : Gypsy moth
Habitat loss/ climate change• When we think of exotic we usually think of species actually transported by people deliberately or accidently but we could include species that are able to expand their home range themselves because of human changes to environment.
Impacts of exotic species• Most exotic species are leaving environment so completely manipulated by people that their direct impacts on native biota are not very severe. Unfortunately there are thousands of exceptions to this organization some of which are following:
Predators and grazers• It is easy to understand the impact of exotic species when an introduces species kills and eats native species.From economic perspective introduced insects that can consume crop plants are among most destructive exotic pests.
Parasites and pathogens• Exotic parasites and pathogens have a tremendous potential to effect native predators and parasites feed on the protoplasm of other species.• European colonist killed far more natives of Australia and Americans with their diseases than their guns.
Competitors• The effects of exotics as Competitors are most prominent with plants and other sessile species.• Some exotic species can become so extremely abundant that competition for space is closely tied to basic resources such as;• water, nutrients,and light.
Hybridization• Some introduced species are so closely related to the native species that they may interbreed and produce hybrids.• The genes of one species come to dominent in a common gene pool largely excluding the genes of second species.This process is called gene swamping.
Impacts on ecosystemImpacts of exotic ecosytem can reach farbeyond the individual species that mustcope with a predator,competitor,pathogensor parasite.Exotic species can alter a variety ofecosystem properties such as productivity,nutrient cycling,soil and vegitationstructure.
• Exotic plants can also exchange the entire ecosystem in many ways for example nitrogen fixing plants can significantly change the soil chemistry of the environment.• They invade fire prone exotic plants. Exotic plants can allow fire to burn more exteremly and entirely change ecosystem.
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