Community Interactions Section 12.1

Introduction Biomes may be very different but they have something important in common. They all have populations of interacting species. Species interact in the same ways in all biomes. All biomes with have predators and prey.

What is a Community? Community is the biotic part of an ecosystem. It is all of the populations of all the species in an area. All of these populations interact. This is an important part of natural selection.

Community Interactions There are three major types of community interactions: Predation Competition Symbiosis

Predation Predation – relationship where one species eats another species. Predator – organism that eats the other. Prey – organism that is eaten. Example: Lion eating Zebra

Predator prey In this Predator-Prey relationship, the spider is eating an insect that it has trapped. http://www.flickr.com/photos/flashmaggie/50552812/

Predator-Prey In a predator-prey relationship one organism benefits and the other is killed.

The Ultimate Predator – a Wildcat! http://www.birdsasart.com/cheetah-w-prey-_T9J1935-Sambura-WR,-Kenya.jpg

Predation and Population Predator-prey relationships keep the populations of both species in balance Limiting factor – limits the growth of an organism, population or process.

Keystone Species Keystone species – a species that is especially important to its community. Example: sea stars and coral reefs Predators to mussels and sea urchins that have no other predators

Adaptations to Predation Predators and prey adapt and evolve through natural selection. One example is camouflage.

Competition The two flowering plants are competing for the same space Which means both of them are harmed. http://elementy.ru/images/eltbook/competitive_exclusion_principle_520.jpg

Competition Competition is when two organisms use the same space and resources at the same time. Intraspecific Competition - occurs between organisms of the same species Interspecific Competition – occurs between organisms of different species Competitive Exclusion Principle – No two species can occupy the same niche in the same habitat at the same time.

Kudzu Competition Kudzu is a plant that was introduced to the United States in 1876 at the Centennial Exposition in Philadelphia, PA. Kudzu does not have any natural predators here – therefore it grows out of control. It “outcompetes” plants that are native so they don’t have a place to grow. Kudzu takes over in areas where it begins to grow. http://news.uns.purdue.edu/images/+2005/nice-kudzu.jpg &imgrefurl=http://www.yahoolavista.com/kudzu/&h=288&w=432&sz=35&hl=en&start=11&tbnid=tp85kKj4SEtsvM:&tbnh=84&tbnw=126&prev=/images%3Fq%3Dkudzu%26svnum%3D10%26hl%3Den%26lr%3D

Competition – introduced species The Eastern Bluebird is being forced into smaller numbers by the House Sparrow, an introduced species. The House Sparrow is a species of birds were introduced to our continent and remain today predators to our native birds and are territorial, aggressive, and take cavities away from our native nesters, including Bluebirds. The House Sparrow attacks Bluebirds, including incubating females and their eggs, nestlings, and will kill and build a nest over the corpses of our native species. http://my.core.com/~paper-images/Eastern_Bluebird022v.jpg http://photogallery.canberrabirds.org.au/images/Sparrow_House_Dabb.jpg

Symbiosis Symbiosis a close relationship between two species where at least one is benefited. There are 3 types of symbiotic relationships: Mutualism Parasitism Commensalism

Mutualism Mutualism is a relationship between two organisms where both of them benefit from the relationship. This can involve providing food, protection, a place to live or even pollination.

Mutualism – clownfish and anemone The clownfish gets protection from the anemone and in return protects the anemone from fish that would eat it (angelfish); the clownfish also keeps the anemone free of dirt and debris. http://www.bigfishhooked.com/clown_fish_and_anenome.jpg

Mutualism - Lichens Lichens consist of a fungus with an algae or photosynthetic bacterium living inside the fungus. The alga provides food for both of them and the fungus provides a habitat for the alga. tbnid=7aE_8wrZkK9LJM:&tbnh=111&tbnw=148&prev=/images%3Fq%3Dlichen%26start%3D20%26ndsp%3D20%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DN

Mutualism – cleaner shrimp These shrimp set up large cleaning stations on the reef where fish will come to have parasites picked from their skin. The shrimp gets a constant food source and the fish (eel in this case) gets rid of potentially dangerous parasites http://www.biologyreference.com/images/biol_04_img0432.jpg

Cleaner Shrimp on a Grouper http://images.google.com/imgres?imgurl=http://www.kasson.com/LCD/Grouper67.jpg&imgrefurl=http://www.kasson.com/LCD/Grouper.htm&h=333&w=500&sz=47&hl=en&start=2&tbnid=h2JaDinHGT3ulM:&tbnh=87&tbnw=130&prev=/images%3Fq%3Dgrouper%2Bcleaner%2Bshrimp%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DG

Mutualism – Ant and Aphid http://www.richsoil.com/antsandaphids/ants_aphids_sugar.jpg

The Aphid and the Ant Aphids feed on the sap of the plant they are on. Ants use their antennae to stimulate the aphids and cause them to excrete from their abdomen a substance called honeydew which is rich in the nutrients ants require. Each worker ant goes from aphid to aphid collecting honeydew which she stores in her abdomen until it's full; then, she returns to the nest and regurgitates to feed other members of the colony. Ants, in return for the honeydew, protect the aphids from predators such as flies, wasps, and beetles. The ants, like human ranchers, sometimes move their aphids to richer grazing grounds. YUMMY!

A Little Aphid Ant Humor http://images.google.com/imgres?imgurl=http://www.ibiblio.org/Dave/Dr-Fun/inline/thumbs/tn20001013.jpg&imgrefurl=http://www.ibiblio.org/Dave/ar00295.htm&h=190&w=258&sz=20&hl=en&start=9&tbnid=5x78fixpPQkJAM:&tbnh=82&tbnw=112&prev=/images%3Fq%3Daphid%2Bant%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DN

Mutualism – sea slug with algae The algae lives in the sea slug and makes food for both of them – in return it gets a place to live. http://www.calacademy.org/science_now/new_species/melibe_digitata.html

Nitrogen fixing nodules Bacteria in the nodules can take nitrogen gas from the atmosphere and turn it into a form that can be used by the plant; in return, the plant protects the bacteria from harmful oxygen and the bacteria get food from the plant. http://www.mobot.org/gardeninghelp/images/pests/179.jpg

Mutualism - pollination Many plants depend on pollinators for their reproduction. They provide nectar to attract these pollinators. So the pollinator gets fed and the plant gets reproduced! http://www.life.uiuc.edu/help/digitalflowers/picts/Asteraceae/15-Liatris%20pollination.jpg

Another Pollinator – note pollen on back legs http://z.about.com/f/wiki/e/en/thumb/3/39/Plumpollen0060.jpg/300px-Plumpollen0060.jpg

Protozoans in cow’s stomach These protozoans along with bacteria help the cow by digesting cellulose; cows don’t have the enzymes to do this. The protozoans and bacteria get a place to live and a continual food source. This is a valuable mutualistic relationship. http://commtechlab.msu.edu/sites/dlc-me/zoo/zac0278.jpg

OxPecker - Mutualism The oxpecker eats parasites on the mammal – food for the bird and removal of danger for the mammal http://blogs.bootsnall.com/Chuck/uploads/Copy%20of%20YellowBilledOxPecker-1.jpg

Caterpillar Ant Mutualism http://www3.nationalgeographic.com/animals/video/ant_caterpillarsymbiosis.html

Commensalism Commensalism is a relationship where one organism benefits and other is neither harmed nor benefited. Few examples of commensalism exist because of the difficulty of showing that one of the organisms is not affected by the other. Some of the former commensalistic relationships may turn out to be mutualism or parasitism.

Cattle Egret - Commensalism The cattle stir up grasshoppers and other insects that the egret likes to eat. There is no apparent benefit to the cow. http://mishami.image.pbase.com/u43/jypsee/upload/27771434.anguswithegret.jpg

Commensalism – shark and remora The remora benefits by getting food from the shark’s meal. But there is no apparent benefit to the shark. http://www.scubaduba.com/gallery/shark2.jpg

Remora without its shark Note the sucker on the head of the remora (or suckerfish) http://www.cincinnatidiving.com/Gallery/images/Shearwater/remora.jpg

Commensalism – whale and barnacle The barnacle larvae swim around, attach to the whale, and form the adult. This habitat is a good one for providing food. The whale does not “appear” to be harmed. http://www.coolantarctica.com/Antarctica%20fact%20file/wildlife/whales/humptail.jpg

Commensalism – limpets on mussel shell

Parasitism Parasitism is a relationship where one individual benefits and the other is harmed. Parasites rarely kill their hosts because to do so would ultimately harm the parasite! Parasite – benefitted Host – harmed A tick!

Parasitism Adult wasps insert their eggs beneath the skin of the hornworm larva. The eggs hatch and the young feed hornworm until they pupate as shown in the photo. Although the parasite is harmful to the worm, it is important in controlling hornworms in agriculture. http://entweb.clemson.edu/cuentres/cesheets/benefici/ce174.htm

Brood Parasitism - Cowbirds females lay their eggs (one per nest) in the nests of other species. The hatchling cowbird is big and gets most of the food. This is because the foster birds tend to feed the largest mouth. The cowbird benefits and the other species is harmed. http://jrscience.wcp.muohio.edu/birds/ohio_birds/images/chipping_sparrow_chick_cowbird-40.jpg

Mistletoe – a plant parasite Mistletoe lives off the branches and stems of Other trees. It can photo- synthesize a little but not enough to meet its needs. The tree can be very harmed. http://www.wcosf.org/other_photos/Mistletoe_1_600.JPG

Heartworms! The worm larvae are transferred from dog to dog through the bite of an infected mosquito. The mosquito sucks larval heartworms with blood from an infected dog. The mosquito then bites another dog and transfers these microscopic larva as it bites. During the next few months, these larva migrate through the dogs body arriving at the heart several months later where they become adults. http://www.greatlakesbcrescue.org/HealthNTraining/heartworms.JPG

Symbiosis Summary + - Symbiosis Type Species A Species B Commensalism Mutualism Parasitism -

Ecological Succession Ecological succession is a process by which an existing ecosystem is gradually replaced by another more stable ecosystem.

Primary Succession Primary succession is succession that occurs on new land. New land is created by events such as volcanic eruptions or retreat of glaciers that scrape away Earth. There is no life and no soil present. The first species that come to the new land are called pioneer species. These are usually lichens or mosses. They slowly break down the surface of the rock where they grow and create soil. Once soil is established, grasses, shrubs, and trees move in from smallest to largest.

Secondary Succession Secondary Succession occurs on land where there was already an ecosystem. Disturbances such as fire, natural disasters, and clearing occur but leave soil intact. Succession can occur more quickly because the pioneer species are not necessary. Herbaceous plants are first to return to the ecosystem, then shrubs and trees quickly return.

Climax Community A climax community is a relatively stable and mature ecosystem. It is made up of a diverse collection of plants and animals whose niches support a healthy ecosystem. If an ecosystem is disturbed (by fire, for ex.) ecological succession will proceed toward a climax community