Succession A series of regular, predictable, quantifiable changes through which ecological communities go through. • Primary succession: “Pioneer species” colonize a newly exposed area (lava flows, glacial retreat, dried lake bed). No soil! • Secondary succession: The community changes following a disturbance (fire, hurricane, logging). Soil present.
Climax CommunityA stable group of plants andanimals that is the end resultof ecological successionDoes not necessarily meanhuge trees. In prairies and saltmarshes the dominant plantsare grasses -- and in desertsthe dominant vegetation arecacti.
Ecosystem Characteristics at Immature and Mature Stages of Ecological Succession Immature Ecosystem Immature EcosystemCharacteristic (Early Successional Stage) (Late Successional Stage)Ecosystem Structure Small LargePlant size Low HighSpecies diversity Mostly producers, few decomposers Mixture of producers, consumers,Trophic structure and decomposers Few, mostly generalizedEcological niches Many, mostly specialized LowCommunity organization High(number of interconnectinglinks)Ecosystem Function Low HighBiomass High LowNet primary productivity Simple, mostly plant herbivore Complex, dominated byFood chains and webs with few decomposers decomposersEfficiency of nutrient recycling Low HighEfficiency of energy use Low High Table
Invasive species A species that spreads widely and rapidly becomes dominant in a community, changing the community’s normal succession Many invasive species are non-native, introduced from other areas. Purple loosestrife invades a wetland. Figure 5.25
Community Interactions The relationship between the different populations of organisms in a geographical area. Some relationships are symbiotic (close, long- term interaction). Some relationships are harmful to a population or species, some are beneficial. Figure 5.25
Predation One species, the predator, hunts, kills, and consumes the other, its prey. Example: Snake captures and eats a frog Figure 5.16
Predation drives adaptationsin preyCryptic coloration: Warning Mimicry:Camouflage to hide coloration: Foolfrom predators Bright colors warn predators that prey is toxic (here, caterpillar mimics Figure 5.18
Competition When multiple species seek the same limited resource Interspecific competition is between two or more species. Intraspecific competition is within a species. Often does not involve active fighting, but subtle contests to procure resources.
Mutualism Symbiotic relationship in which both species benefit one another. Example:Hummingbird pollinates flower whilegaining nectar for itself. Figure 5.22
Mutualism ExamplesOxpeckers and black rhinoceros Clown fish and sea anemone Mycorrhizae fungi on juniper Lack of mycorrhizae fungi on seedlings in normal soil juniper seedlings in sterilized soil
Commensalism Symbiotic relationship in which one species benefits and the other is unaffected.Example: Cattleegrets feast oninsects that arearoused into flight bycattle grazing in theinsects habitat. TheCattle does notbenefit at all Figure 5.22
ParasitismSymbiotic relationship in which one species,the parasite, exploits the other species, thehost, gaining benefits and doing harm. Example: Tick feeding on blood and transmitting disease Figure 5.21