2What Shapes an Ecosystem? Biotic Factors – living/biological influences on organisms within an ecosystem.Examples?Abiotic Factors – physical/non-living influences on organisms within an ecosystem.*Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives = habitat (= home of organism; its “address”)
3Abiotic and Biotic Factors Abiotic FactorsBiotic FactorsECOSYSTEM
4Abiotic and Biotic Factors Abiotic FactorsBiotic FactorsECOSYSTEM
5Abiotic Factors of the Biosphere: Energy Source Not all areas on Earth receive the same amount of light energyIn aquatic enviroments, light cannot reach far down, so photosynthesis tends to occur near the surface of the water
6Abiotic Factors of the Biosphere: Temperature Temperature affects metabolism.Few organisms can maintain a sufficiently active metabolism at temperatures close to 0ºC.Temperatures above 45ºC destroy the enzymes of most organisms.Most organisms function best within a specific range of environmental temperatures.
7Abiotic Factors of the Biosphere: Water Water is essential to all life.For terrestrial organisms, the main water problem is drying out.Aquatic organismsare surrounded by water andface problems of water balance if their own solute concentration does not match that of their surroundings.
8Abiotic Factors of the Biosphere: Inorganic Nutrients The distribution and abundance of plants are often determined by theavailability of inorganic nutrients such as nitrogen and phosphorus andthe structure, pH, and nutrient content of the soil.In many aquatic ecosystems, the growth of algae and photosynthetic bacteria is often limited by levels ofnitrogen andphosphorus.
9Abiotic Factors of the Biosphere: Other Factors Aquatic but not terrestrial ecosystems are more limited bythe levels of dissolved oxygen,salinity,currents, andtides.Terrestrial but not aquatic ecosystems are more limited bywind,storms, orfire.
14Adjusting to Environmental Variability The abiotic factors in a habitat may varyfrom year to year,seasonally, orover the course of a day.For example: Birds may adjust to cold bymigrating to warmer regions (a behavioral response),growing heavier feathers (an anatomical response), orfluffing up their feathers to trap more heat (a physiological response).
15Adjusting to Environmental Variability: Physiological Acclimation isgradual, reversible, anda physiological adjustment to an environmental change.The ability to acclimate is generally related to the range of environmental conditions a species naturally experiences.Among vertebrates,birds and mammals can tolerate the greatest temperature extremes because they are endotherms, whileectothermic reptiles can only tolerate a more limited range of temperatures.
16Adjusting to Environmental Variability: Anatomical Many organisms respond to environmental challenges with some type of change inbody shape andstructure.Anatomical responses are not reversible – growth and development is limited – trees grow smaller in very windy enviroments
17Adjusting to Environmental Variability: Behavioral In contrast to plants, most animals can respond to an unfavorable change in the environment by moving to a new location.Ectotherms may shuttle between sun and shade.Migratory birds travel great distances in response to changing seasons.Humans have an especially rich range of behavioral responses.
18The Niche Niche = the ROLE of an organism in its habitat What is the organism’s job?What does the organism do for its environment?The niche is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions – use of biotic and abiotic resourcesplace in food web, range of temperatures needed to survive, food, physical conditions necessary for survival, reproduction, etc.
19Warblers and Their Niches Cape May WarblerFeeds at the tips of branchesnear the top of the treeBay-Breasted WarblerFeeds in the middlepart of the treeYellow-Rumped WarblerFeeds in the lower part of the tree andat the bases of the middle branchesSpruce tree
20Competitive Exclusion Principle Competitive Exclusion Principle - no two species can share the exact niche in the same habitat at the same time…Why? One will become extinct.
21Separate cultures Combined cultures 2 4 6 8 10 12 14 16 P. aurelia Relative population densityCombinedcultures246810121416P. aureliaP. caudatum
22Community Interactions - Interspecific Interspecific interactions are interactions between species.Powerfully affect an ecosystemFour important types of interactionsCompetitionPredationHerbivorySymbiosis
23CompetitionCompetition – organisms compete for resources (food, water, shelter, etc)
24PredationPredation – one organism (predator) captures and feeds on another (prey)
25PredationNumerous adaptations for predator avoidance have evolved in prey populations through natural selection.Cryptic coloration iscamouflage anda way for prey to hide from predators.A warning coloration isa brightly colored pattern anda way to warn predators that an animal has an effective chemical defense.
26Predation Non-venomous scarlett king snake Venomous eastern coral snake
27HerbivoryHerbivory is the consumption of plant parts or algae by an animal.Plants have evolved numerous defenses against herbivory, includingspines,thorns, andchemical toxins.
28Symbiosis Symbiosis – two species live closely together Three major types of symbiosisMutualismCommensalismParasitism
29Symbiosis - Mutualism Host Symbiont Example: flower & bee – both organisms benefit from each otherOther examples?
35Ecological Succession Ecological Succession – series of predictable changes that occurs in a community over time*Ecosystems are constantly changing in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.
36Primary SuccessionBare rock to plant community – like on a volcanic islandFirst species to populate are called pioneer species (usually lichens)No soil – have to make it by breaking down rocks first