Lecture 6 Communities and Ecosystems Lecture 6 1. Biological Communities Ecological Niche Species Interactions Keystone Species Community Development 2. Ecosystems Terrestrial Aquatic 1
Biological Communities Ecology Hierarchy Part of Earth that contains living organisms Community and physical environment All populations of species in an area Group of same species Individuals 2
Biological Communities Association of different populations of organisms that live and interact in same place at same time Biological Communities When include non-living environment, termed ecosystem 3
Ecological Niche Ecological Niche An Ecological Niche is an organism s role in the community. The totality of an organism s adaptations, its use of resources, and the lifestyle to which it is fitted 4
Ecological Niche The Niche takes into account all aspect of an organism s existence Physical, chemical, biological factors needed to survive Habitat Abiotic components of the environment Ecological Niche 5
Limiting Resources Any environmental resource that, because it is scarce or at unfavorable levels, restricts the ecological niche of an organism Ex: nutrients, food, territory, water Organisms compete when resources are not plentiful Fundamental Niche Ecological Niche Ideal ecological niche, no restrictions Realized Niche Actual niche the organism occupies 6
Ecological Niche 7
Species Interactions Competition Competition Interaction among organisms that vie for the same resource in an ecosystem Intraspecific Competition between individuals in a population Interspecific Competition between individuals in 2 different species 8
Interspecific Competition Species have different K values When grown together, P. aurelia outcompetes Competitive Exclusion & Resource Petitioning Competitive Exclusion One species excludes another from a portion of the same niche as a result of competition for resources Resource Partitioning (below) Coexisting species niche differ from each other 9
Ecological Niche Fundamental Niche vs Realized Niche Ex: Green Anole and Brown Anole Ecological Niche Green Anole and Brown Anole Fundamental niches of 2 lizards initially overlapped Brown anole eventually out-competed the green anole for resources Drove out green anole, thereby reducing the green anole s realized niche 10
Species Interactions Symbiosis Symbiosis An intimate relationship between members of 2 or more species Participants may: Benefit, Be harmed Unaffected by the relationship Result of coevolution 11
Symbiosis Three types of symbiosis Mutualism Commensalism Parasitism Mutualism Symbiotic relationship in which both members benefit Example: 12
Commensalism Symbiotic relationship where one species benefits and the other is neither harmed nor helped Example: Parasitism Symbiotic relationship in which one species is benefited and the other is harmed Parasites rarely kill their hosts Ex: ticks Ticks attach themselves to skin of animals and consume their blood 13
Species Interactions Predation Predation The consumption of one species by another Many predator-prey interactions Most common is pursuit and ambush (hunting) Plants and animals have established specific defenses against predation through evolution 14
Pursuit and Ambush Pursuing prey - chasing prey down and catching it Pursuit and Ambush Ambush - predators catch prey unaware 15
Defensive Adaptation of Animals Fleeing or running Defensive Adaptation of Animals Mechanical defenses Ex: quills of porcupines, shell of turtles 16
Defensive Adaptation of Animals Living in groups Defensive Adaptation of Animals Warning coloration 17
Defensive Adaptation of Animals Cryptic Coloration Animals blend into surroundings Helps animals hide from predators Example: pygmy sea horse on gorgonian coral Plant Defenses Against Herbivores Plants cannot flee predators Adaptations Spikes, thorns, leathery leaves, thick wax 18
Plant Defenses Against Herbivores Plants cannot flee predators Adaptations Protective chemicals that are poisonous or unpalatable Examples: active chemicals in tobacco, opium poppy, marijuana, peyote Milkweeds produce cardiac glycosides and deadly alkaloids Plant Defenses Against Herbivores 19
Keystone Species Keystone Species A species, often a predator, that exerts profound influence on a community More important to the community than what would be expected based on abundance 20
Keystone Species The dependence of other species on the keystone species is apparent when the keystone species is removed Keystone Species Protecting keystone species is a goal to conservation biologists 21
Keystone Species Keystone Species 22
Community Development Community Development Ecological Succession- the process where a community develops slowly through a series of species Earlier species alter the environment in some way to make it more habitable by other species As more species arrive, the earlier species are outcompeted and replaced 23
Community Development Two types of Ecological Succession Primary succession Secondary succession Primary Succession Succession that begins in a previously uninhabited environment No soil is present Ex: bare rocks, cooled lava fields, sand dunes etc. General Succession Pattern Lichen secrete acids that crumble the rock (soil begins to form) Lichen mosses grasses shrubs forests 24
1 2 3 Primary Succession 1. Barren landscape rock with lichen & small shrubs 2. Dwarf trees & shrubs 3. Spruces dominate Secondary Succession Succession that begins in an environment following destruction of all or part of the earlier community Ex: abandoned farmland, open area after fire Generally occurs more rapidly than primary succession 25
Secondary Succession of an abandoned farm field in North Carolina Ecosystems 26
Earth s Ecosystems Terrestrial vs. Aquatic Earth s Major Biomes Terrestrial Biome A large, relatively distinct terrestrial region with a similar climate soil, plants, and animals, regardless of where it occurs in the world Nine major biomes Earth has many climates and characteristics organisms have adapted forming biomes 27
Earth s Major Biomes Location of each biome is primarily determined by: Temperature (varies with both latitude and elevation) Precipitation Earth s Major Biomes 28
Chaparral Also called a Mediterranean Climate Ex: Southern California Ex: Greece 29
Chaparral Chaparral 30
Chaparral Chaparral Soil is thin and often not fertile Vegetation Dense growth of evergreen shrubs Lush during the growing season Animals Mule deer, chipmunks, many species of birds 31
Tropical Rainforest Lush, species-rich biome that occurs where climate is warm and moist throughout the year Tropical Rainforest 32
Tropical Rainforest Precipitation 200 450 cm/yr Tropical Rainforest Ancient, weathered, nutrient-poor soil Nutrients tied up in vegetation, not soil Vegetation 3 distinct canopy layers Animals Most abundant insect, reptiles and amphibians on earth 33
Tundra Arctic or alpine tundra Treeless biome in the far north with harsh, cold winters and extremely short summers Precipitation 10 25 cm/yr Temperature Short growing season 50 160 days Tundra Arctic or alpine tundra Treeless biome in the far north with harsh, cold winters and extremely short summers Precipitation 10 25 cm/yr Temperature Short growing season 50 160 days 34
Arctic or alpine tundra Tundra Treeless biome in the far north with harsh, cold winters and extremely short summers Tundra 35
Tundra Precipitation 10 25 cm/yr Temperature Short growing season 50 160 days Tundra Nutrient poor soils with little organic material Permafrost present Low species richness Vegetation is mostly grasses and sedges Very simple food web Low primary productivity 36
Aquatic Ecosystem Fundamental Division Freshwater Saltwater Aquatic Ecosystems also affected by Dissolved oxygen level, light penetration, ph, presence/absence of currents Aquatic Ecosystem Three main ecological categories of organisms 1. Plankton- free floating Phytoplankton photosynthetic Zooplankton animal-like 37
Aquatic Ecosystem Three main ecological categories of organisms 2. Nekton - strong swimming 3. Benthos - bottom dwelling Freshwater Ecosystems Includes: Rivers and streams (lotic or flowing waters) Lakes and ponds (lentic or standing water) Marshes and swamps (standing water) Represent 2% of earth s surface Assist in recycling water back to the oceans 38
Rivers and Streams Headwater streams Larger streams and rivers River Continuum Concept Water moves from headwaters to rivers to coastal ocean Change in physical features and food sources (abiotic differences) Results in change in biological features and ecosystem function In streams, organisms adapted to fast flowing water (hooks, suctions, flattened bodies) In rivers, adaptation for swimming (streamlined) 39
River Continuum Concept Water moves from headwaters to rivers to coastal ocean In streams, organisms adapted to fast flowing water (hooks, suctions, flattened bodies) In rivers, adaptation for swimming (streamlined) Rivers and Streams Estuaries, deltas, coastal ocean Physical nature of aquatic ecosystems changes significantly 40
Lakes and Ponds Body of freshwater that does not flow Ecosystem Services Important environmental benefits that ecosystems provide, such as: Clean air to breathe Clean water to drink Fertile soil in which to grow crops 41
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