2Community Interactions Habitat is a place where an organism lives and it is characterized by distinctive physical and chemical features, as well as the array of species living in it.Community is an association of the populations of all species that occupy the same habitatPopulation - all individuals of the same species that are occupying a specific areaNiche - sum total of all activities and relationships in which individuals of a species engage as they secure and use the resources requires to survive and reproduceHabitat - place where an organisms or species lives; characterized by its physical and chemical features and its speciesCommunity - all populations in a habitat. Also, a group of organisms with similar life-styles.Ecosystem - array of organisms, together with their environment, interacting through a flow of energy and a cycling of materialsBiosphere - all regions of the earth’s waters, curst and atomosphere in which organisms live
3Niche - the sum of all activities and relationships in which its individuals engage as they secure and use the resources required for their survival and reproduction.The fundamental (potential) niche is the one that could prevail in the absence of competitionThe realized niche result from shifts in large and small ways over time, as individuals of the species respond to changes
4Categories of Species Interactions Interactions can occur b/w any two species in a communitySeveral types of species interactions -(1) Commensalism - one species benefits and the other is not affected (ex. Bird’s nest in a tree)(2) Mutualism - a symbiotic relationship where both species benefit (plants and their pollinators)(3) Parasitism - one species (parasite) benefits while the other (host) is harmed.(4) Competition - both species are harmed by the interaction(5) Predation
5Competitive Exclusion Competitive Exclusion suggests that complete competitors cannot coexist indefinitely.- When competitor’s niches do not overlap as much, the coexistence is more probable- Differences in adaptive traits will give certain species the competitive edge.
6Resource Partitioning Resource Partitioning - similar species share the same resources in different ways.Arises in 2 ways:(1) Ecological differences b/w established & competing populations may increase through natural selection(2) only species that are dissimilar from established ones can succeed in joining an existing communityBristlyfoxtailResource partitioning - the subdividing of some category of similar resources that lets competing species coexist.Each species is adapted to exploiting a different portion of the habitatDrought-tolerant foxtail grasses have shallow roots fibrous roots that quickly abosrb rainwater. They grow where moisture in the soil varies from day to day.Mallow plants, with a taproot system, grow in deeper soil that is moist early in the growing season but drier later.Smartweed's taproot system branches in topsoil and soil below the roots of the other species. It grows where soil is continuously moistIndianmallowSmartweed
8Predation Predation vs. Parasitism : Predators get their food from prey, but they do not take up residence on or in the prey, typically their prey are killed outright or mutilated.Parasites get their food from host, and they live on or in the host for a good part of their life cycle; they may or may not kill the host.Many of the adaptations of predators and their victims arose through coevolution - the joint evolution of two or more species that exert selection pressure on each other as an outcome of close ecological interaction.
9Adaptations that arise as a result of Predator-Prey Interactions … Coevolution
10Camouflage- any adaptation in form, color, patterning, or behavior that allows a prey or predator to blend with its surroundingsDesert plant, Lithops, resembles a small rock.Only during a brief rainy season does Lithops flower.This is when other plants grow profusely and divert herbivores from Lithops - and when free water instead of juicy plant tissues are available to quench an animals thirst.
11Warning Coloration - Toxic prey offer bright colors or bold patterns that serve as a warning to predatorsMimicry - Prey not equipped with defenses may escape predation by resembling toxic preyMonarch butterflyMimicYellow JacketTaste badHighly toxic - often have warning coloration or conspicuous patternsInflict pain on attackersMimicMimic
12Moment-of-truth Defense - allow prey animals to defend themselves by startling or intimidating the predator with display behaviorPredator Response to Prey — adaptations used by predators to counter prey defenses
13Forces Contributing to Community Stability Succession modelEcological succession - is the predictable developmental sequence of species in a communityPioneer species - first to colonize an areaClimax community - most persistent array of species that results after some lapse of timePrimary succession - happens in an area that was devoid of life and begins with a pioneer species (ex. new volcanic island or land exposed when a glacier retreats)Secondary succession - is when a community re-establishes itself to a climax state after a disturbance (abandoned fields, burned forest)
14Community Instability Keystone species - a dominant species that can dictate community structure
16Caulerpa taxifolia suffocating a marine ecosystem
17Mainland and Marine Patterns Tropics - Greatest number of coexisting speciesResource availability is greatest b/c more rainfall & sunlightSpecies diversity might be self-reinforcingRates of speciation in the tropics have exceeded those of background extinction