BESC 201 1st Edition Lecture 9 Outline of Last Lecture I Levels or Ecological Organization Population Ecology Outline of Current Lecture II Central Case Study of Chapter 4 III Species Interactions IV Ecological Communities V Earth s Biomes Current Lecture Species Interactions and Community Ecology Central Case Study Black and White and Spread All Over Zebra Mussels Invade the Great Lakes Native to Western Asia and Eastern Europe Colonized 30 states by 2010 because of no predators competitors or parasites Zebra mussels clog water intake pipes and deplete phytoplankton foundation of food web Quagga mussels are starting to replace the Zebra mussel Species Interactions Competition can occur when resources are limited Competition when multiple organisms seek the same limited resource Subtle and indirect Intraspecific Competition competitive interactions between members of the same species Interspecific Competition competitive interactions between members of different species Resource Partitioning species divide the resource they use in common by specializing in different ways Predators kill and consume prey Predation individuals predator hunt kill and consume prey Predation can drive population dynamics Natural selection leads evolutionary adaptations to make each counterpart compete to get the upper hand These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Parasites exploit living hosts Parasitism the parasite depends on the host for nourishment while harming the host at the same time Parasitism usually doesn t involve killing the host Types on contact infrequently live inside host s body exterior of host Parasitoids insects parasitizing other insects killing them in the process Coevolution parasites and hosts evolving in response to each other Evolutionary Arms Race hosts and parasites become locked in a duel of escalating adaptations Herbivores exploit plants Herbivory animals feed on tissues of plants Plants may produce toxins thorns spines or irritating hairs in defense Mutualists benefit one another Mutualism two or more species benefit from interacting Symbiosis physically close association between interacting species either mutualistic or parasitic interactions Pollination free living organisms transfer pollen from flower to flower may encounter each other only one Ecological Communities Energy passes among tropic levels Trophic Level a rank in the feeding hierarchy Producers Consumers Detritivores and decomposers o Detritivores scavenge waste products or dead bodies soil insects o Decomposers break down leaf litter and nonliving matter fungi Energy numbers and biomass decrease at higher trophic levels Only a small portion of the energy is transferred to the next trophic level Biomass the collective mass of living matter in a given place and time Food webs show feeing relationships and energy flow Food web map of feeding relationships and energy flow that uses arrows to show paths in which energy passes among organisms Zebra Quagga mussels altered Great Lakes by shifting productivity from open water regions to benthic bottom and littoral near shore regions Some organisms play bigger roles in communities than others Keystone species a species with a strong impact by controlling populations Large bodied secondary or tertiary consumer Trophic cascade indirectly promoting populations of organisms at lower trophic levels by keeping species at intermediate levels in check Ecosystem Engineers species that physically modify environment beavers Communities respond to disturbance in different ways Resistance a community that resists change and remains stable Resilience a community changes in response then returns to its original state A community may also be modified permanently Succession follows severe disturbance Succession a predictable series of changes a disturbed community goes through Primary Succession a disturbance so severe that no soil life remains community built from scratch Secondary Succession disturbance alters community remaining elements are used as building blocks Pioneer Species species that arrive first and colonize the community Have spores or seeds that travel far Lichens pioneers best suited for bare rock firm hold on rock and increased moisture and acids break down for beginning of soil formation Climax Community fully successed environment with stability until next disturbance that restarts succession Communities may undergo shifts Community change is more variable and less predictable than models of succession suggests Phase Shift Regime Shift the overall character of the community fundamentally changes Example coral reefs are now dominated by algae because of humans Invasive species pose new threats to community stability Invasive Species a non native species spreading widely and becoming dominant in a community Introduced species can become invasive when limiting factors that normally regulate population growth are absent Invasive species usually seen as negative but in time people see beauty of them in gardens and they may be used for biocontrol Control measures are so expensive that preventative strategies are better Altered communities can be restored Restoration Ecology These ecologists research historical conditions of ecological communities as they existed before industrialization altered them Ecological Restoration The actual hands on efforts to restore communities Visions may be to either restore functionality of the system wetland s ability to filter water or to return community to complete pre settlement state Largest restoration project Florida Everglades Best to protect natural systems from degradation in first place Earth s Biomes Biome large scale ecological unit recognized mostly by its dominant plant type and vegetation structure Climate influences the locations of biomes Temperature and precipitation are two biggest factors determining biome placement Climate Diagrams Climatographs depict where biomes occur Aquatic and coastal systems also show biome like patterns Biomass traditionally used for terrestrial systems only Coastal systems frequently include both terrestrial and aquatic components Aquatic systems shaped by water temperature salinity currents depth and light levels We can divide the world into roughly ten terrestrial biomass Temperate Deciduous Forest broad leafed trees that lose leaves each fall and dormant in winter