Ecological Niche A description of the role played by a species in a biologic community and The total...

Ecological Niche

• A description of the role played by a species in a biologic community

and

• The total set of environmental conditions/factors that determine a species distribution

Generalist

• A species that can adapt to a wide range of environments (“r-adapted”)

– raccoons, rats, wolves, dandelions

• Can adept quickly to changes • Opportunistic - appear quickly

wherever an opening exists. • Pioneer species - first to appear

Specialist • A species specifically adapted to a very

narrow niche or range of conditions (“K-adapted”)

– pandas, koalas, wild roses

• Much less resilient to change, adept very slowly

Law of Competition

• no two species will occupy the same ecological niche and compete for exactly the same resources in the same habitat for very long.– One group or the other will gain an advantage

forcing the other group to move or change behavior or become extinct

– resource partitioning - adaptations geared to reduce competition in the same habitat

Species Interactions

• Predation – Predator - any organism that feeds

directly on another living organism (Carnivores prey on other animals, Herbivores prey on plants,

Omnivore prey on both

• Parasites and pathogens can also be considered predators

• Competition

– Intraspecific competition

• competition within a species

– Interspecific competition -

• competition between species

Can result in Coevolution

• Symbiosis

• the intimate living together of members of two or more species

• Unlike predation and competition, symbiosis can be beneficial to all involved parties (but not always).

• Commensalism: - "eating together at the same table" - in this association one member, usually the smaller, derives benefit from the association, whereas for the other member, the association is neither beneficial or harmful. The relationship can be that of sharing space, substrate, defense, shelter, transport or food.

• Ex. Some species of barnacles are found only as commensals on the jaws of whales.

• The Remora fish (Echeniedea) is a long slender fish which has its dorsal fin modified as a sucker-like attachment organ. It attaches to the sides of larger fish and turtles using them as transport hosts but in addition, obtains food fragments dropped from the host.

• Mutualism: As the name would suggest this is an association in which both organisms derive mutual benefit.

• associations are seen in cleaning fish often seen around sharks feeding on parasites in the mouth and gills. The Egyptian plover performs a similar service by cleaning the mouth of crocodiles.

• Tick birds on rhinos and ox pecker birds on various antelopes also share a mutual relationship. In addition to removing ticks and other irritating insects, the ox peckers often signal the presence of predators to the antelopes.

• Parasitism

• " A parasite is an organism living in or on another living organism, obtaining from it part or all of its organic nutriment, usually to the detriment of its host.“

• Examples of parasitism include: tick-dog; tapeworm-human.

Defensive Mechanisms

• Development of some mechanism by which to hide better or to defend oneself from attack. Toxins, smells, stingers or nettles, body armor

Mimicry • Evolving to look like something else

– looking like a more dangerous animal– looking like something inedible – looking safe - thereby preying on other

organisms

• From left to right are the Common Wasp, Vespula vulgaris, and some of its mimics - the Hornet Moth, Sesia apiformis, the Wasp Beetle, Clytus arietis, and the Hoverfly, Syrphus ribesii.

Keystone Species

• a species or group of species whose impact or involvement on its community/ecosystem is larger or more influential than expected from its mere abundance

• Absence of this/these species can reek havoc on an ecosystem

BiomeBiome

• “life zones” environments with similar climate, topography, soil conditions, and roughly similar biologic communities

– Tundra, Tropical Rainforest, Grassland, …

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

World biome mapFigure 5.3

5-1

Biodiversity Biodiversity • the variety of living things

– genetic diversity - The genetic diversity within a species is primarily the variety of populations that comprise it. (populations with different genes).

– species diversity- a “population” the individuals of a species that live together, group from which mates are chosen

– ecological diversity - the entire composition of a biologic community

– habitat diversity- the variety of places where life exists -- coral reefs, old-growth forests in the Pacific Northwest, tallgrass prairie,


Known living species

5-5

1.4 million KNOWN species

estimate that there are between 3 and 50 million species


Biodiversity “hot spots”Figure 5.20

5-6

Hotspot - a concentration of the worlds biodiversity

- commonly equatorial or island based

Benefits

• Food

• Drugs and Medicine (> 50% of all medications contain some natural products)

• Ecological Benefits - soil production, nutrient cycling, food production, water cycling and purification

• Aesthetic and Cultural


Natural medicinal products

5-7

Human Caused Reductions

• Habitat Destruction– Fragmentation

• Hunting and Fishing

• Commercial Products

• Live Specimen Trade

• Predator and Pest Control


Mass extinctions

5-8


Human disturbance

5-9


U.S. wetland acreageFigure 5.24

5-10


Extinctions and population - Minimum Viable PopulationFigure 5.27

5-12 Source: Data from H. L. Jones and J. Diamond, “Short-term-base Studies of Turnover in Breeding Bird Populations on the California Coast Island,” in Condor, vol. 78:526-549, 1976.


Endangered species

5-13

Exotic Species

• Exotic organisms are organisms which are introduced into habitats/ecosystems where they are not native (i.e. did not evolve within that community)

• one of the greatest threats to biodiversity worldwide !

Kudzu vine

Introduced in 1930s by US Soil Conservation Service to control soil erosion

Kudzu vine

Leafy spurge

Introduced in 1870s by farmers from RussiaThe entire plant is poisonous and crowds out food crops

Leafy spurge

Purple Loosestrife

Introduced by gardeners in early 1800s for its pretty purple flowers. Grows anywhere it is wet, chokes wetlands, rendering them inhospitable to native plants and wildlife

Purple Loosestrife

Zebra Mussels

Discovered in North America in 1988. Marine biologists believe it arrived by transatlantic ship-an undetected stowaway in ballast water that was discharged, mussel larvae and all, into Lake St. Clair, between Lakes Huron and Erie. Since then, the prolific creature has spread rapidly throughout lakes and waterways of the eastern United States and Canada, from the Great Lakes through the Mississippi River drainage. It remains unchecked by predators or parasites.

Zebra Mussels

Asian Long-Horned Beetles

Introduced in 1996, from Chinathis is a wood eating insect withno natural predator in the UnitedStates

Asian Long-Horned Beetles

Flathead Catfish

• Not all destructive alien species come from distant lands. The flathead catfish poses no threat within its native range of the lower Great Lakes, Mississippi River basin, and parts of the Gulf slope drainage. But when introduced to new waters as a sportfish, it's a different story. Now found in the rivers and reservoirs of 18 states where it was previously unknown, this catfish is depleting native fish populations.

Flathead Catfish

Brown tree snake

• On the Pacific island of Guam, the forests are strangely silent, devoid of bird song. There are no bird songs because there are few birds. They have been wiped out by the brown tree snake (Boiga irregularis). A native of the Solomon Islands, Papua New Guinea, and northern Australia, the reptile was accidentally introduced to Guam in the 1940s. It probably arrived via military transports after World War II. Since then, the snake has spread throughout the island, reaching numbers of 12,000 per square mile in some forested areas.

Brown Tree Snake

If you are interested in this more information can be found at :

http://www.invasivespecies.gov/

www.natureserve.org/publications/leastwanted/index.htm

Ecological Niche A description of the role played by a species in a biologic community and The total...

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