Presentation on theme: "Ecosystem Ecosystem = community (all biotic elements) plus physical environment (all abiotic elements) Ecology = study of interrelationships between biotic."— Presentation transcript:
Ecosystem Ecosystem = community (all biotic elements) plus physical environment (all abiotic elements) Ecology = study of interrelationships between biotic and abiotic elements in an ecosystem
Habitat Habitat = any part of the Earth where a species can live, temporarily or permanently = organism’s physical surroundings = where an organism lives
Ecological Niche Ecological Niche = functional role of a species in the community, including habitat, activities & relationships = what an organism does, its occupation
Abiotic Factors Sunlight Water Air Climate (Temperature, precipitation, wind) Soil & Rocks Periodic disturbances
Key Properties of Communities 1) Diversity = variety of different organisms 2) Prevalent Form of Vegetation 3) Stability = ability to resist change 4) Trophic Structure
Species Diversity Species diversity evaluated based on two factors; 1) Species Richness = total number of different species 2) Relative Abundance or Evenness = number of fairly common or noticeable species
Species Richness ? Relative Abundance ? Species Diversity
Interspecific Interactions in a Community 1) Competition 2) Predation (predator-prey or herbivore-plant) 3) Symbiosis
Competition Interspecific Competition = between different species VS Intraspecific Competition = within the same species
Competitive Exclusion Principle Competitive Exclusion Principle = no two species can occupy the same niche at the same time OR = two species so similar that they compete for the same limiting resources cannot coexist in the same place - G. F. Gause
Competitive Exclusion Principle
Chthamalus vs Balanus two species of barnacles
Intertidal Ecology: Foundations of Experimental Community Ecology Joseph Connell, 1961 The Pattern: Barnacle distributions in rocky intertidal zones Mean High Water Spring Tide Mean High Water Neap Tide Mean Low Water Neap Tide Mean Low Water Spring Tide Chthalamus stellatus Balanus balanoides Range of weak (neap) tide
What causes distribution pattern of Chthamalus? Three Different Hypotheses: Chthamalus distribution is determined by; 1. physical factors 2. predation by the snail, Thais lapillus 3. space competition with Balanus
Mean High Water Spring Tide Mean High Water Neap Tide Mean Low Water Neap Tide Mean Low Water Spring Tide Chthamulus stellatus Balanus balanoides Rock Settled Chthamalus (1) Moved rocks with Chthamalus to regions throughout intertidal Test Hypothesis #1: Chthamalus distribution is determined by physical factors In absence of Balanus, Chthamalus enjoyed high survival throughout intertidal zone physical factors not important
Mean High Water Spring Tide Mean High Water Neap Tide Mean Low Water Neap Tide Mean Low Water Spring Tide Chthamalus stellatus Balanus balanoides Snail exclosure Performed a snail exclosure experiment Test Hypothesis #2: Chthamalus distribution is determined by predation by the snail, Thais lapillus Snail exclosure had no affect on Chthamalus survival snail predation not important
Mean High Water Spring Tide Mean High Water Neap Tide Mean Low Water Neap Tide Mean Low Water Spring Tide Chthamalus stellatus Balanus balanoides Rock Settled Chthamalus and Balanus On rocks settled by both species, partitioned rock in ½ and removed all Balanus from one side. Test Hypothesis #3: Chthamalus distribution is determined by space competition with Balanus Balanus removal greatly enhanced Chthamalus survival competition for space is important
Competitive Exclusion Principle Loser must adapt or be eliminated One possibility is Resource Partitioning, they use the same resource at different times, ways, or places (at least one difference between the two organism’s niches) What was the difference between the barnacles niches?
Resource Partitioning Competitors segregate to avoid competition based on; Size of food Type of food Habitat usage Feeding times lions hunt large prey, leopards smaller prey
Resource Partitioning hawks hunt in daytime, owls at night
Predation Predation = consumption of one species “prey” by another “predator”, also includes herbivores eating plants What are some adaptations that have evolved in predators and in prey?
Selective Pressures Selective pressures are elements of an organism’s environment that make an adaptation advantageous. Identify the selective pressure for the following adaptations; Long, thick fur Thorns Fangs Camouflage Production of beta lactamase
Symbiotic Relationships Species #1 Species #2 1) Parasitismbenefitsharms 2) Mutualismbenefitsbenefits 3) Commensalismbenefitsneutral
Parasitism Parasitism is where the parasite gets nourishment from the host, much like predation except host is usually not killed immediately. Example; Plasmodium vivax invades RBC, causing them to burst and triggering the chills & fever of malaria
Mutualism Examples; Honey bees get nectar while pollinating flowers Rhizobium, N 2 - fixing bacteria that provide nitrogen to plants in return for glucose from the plant Mycorrhizae fungi living in plant roots that increase plant’s absorption of nutrients & fungi get nutrition from the plant
Mycorrhizae fungi living in plant roots
Mycorrhizae fungi increase absorption of nutrients by plants
Commensalism In commensalism the host often provides a home or transportation For example; Remoras attached to sharks
Commensalism Examples of commensalism; Epiphytes which are plants that grow on plants E. coli bacteria that live in human intestine
Life on a Leaf A look at the fungal community that grows on healthy new leaves. Includes examples of a variety of interrelationships between organisms.
Heterotrophs Digest food externally & absorb small nutrient molecules Most are multicellular (yeast = unicellular) Form a mycelium, which is a netlike mass of filaments called hyphae Hyphae grow & extend around and through food source
Hyphae grow longer, not thicker – WHY?
Production of antibiotic by Penicillium fungus What type of relationship?
Fungi Fungi grow FAST – one mycelium can add up to a kilometer of hyphae per day Hyphae grow through or around plant cells (enzymes digest plant cells) If fungus grows on dead plant = relationship ?? If fungus grows on live plant = relationship ??
Fungal Reproduction Yeast is unicellular and reproduces by dividing into two new cells Sexual or Asexual?
Fungal Reproduction In multicellular fungi, sometimes two different hyphae fuse together (combining their DNA) and produce a spore Spore develops into new mycelium
Fungal Life Cycle
Mycelium can live a LONG time in the soil In Northern Michigan one mycelium formed from a single spore about 1500 years ago covers about 30 acres In Oregon a single mycelium is 3.4 miles in diameter, covers 2200 acres, weighs 100s of tons and is at least 2400 years old
Coevolution Coevolution is when the adaptations of two species are closely connected – that is when an adaptation in one species leads to a counter adaptation in a second species. Coevolution is when two species, with a close ecological relationship, act as selective pressures for each other
Adaptation = the passionflower vines, Passiflora, produce toxic chemicals that protect their leaves Counter adaptation = Heliconius butterfly caterpillars eat the leaves – they have enzymes that break down toxic chemicals Coevolution
Behavioral adaptation by Heliconius females is not laying eggs on leaves with bright yellow eggs already on them which would reduce intraspecific competition
Some passionflower vines have sugar secreting glands that mimic the eggs, and attract ants & wasps that prey on Heliconius eggs & larvae
Coevolution Adaptation = Bats use echolocation to “see” prey (beams of ultrasonic sound waves, kHz, & the returning echoes) Counter adaptation = some insects (lacewings, praying mantises, most moths) can hear high- pitched sound waves
Bats in search mode send out “clicks” at 10 to 20/sec, When they get closer to prey the rate increases up to several 100/sec just prior to snatching prey Bats detect prey over short range – 5 to 10 m When moths detect clicks 40 m away, they fly away from the slow click rate If fast click rate is detected they take evasive maneuvers (power dives, barrel rolls, etc)
Counter adaptation = tiger moths generate their own clicks Warns bat of bad tasting prey (avoid after 1 st taste) Startle the bat (bats do get used to it) “jam” the sonar = interfere with bats ability to pinpoint prey Only works if clicks arrive with 1 st returning echo, so window of opportunity only 1/1,000 sec Bats still catch >50% of prey they attack
Counter-counter adaptation = tropical “gleaning” bats use ultra high frequency (up to 212 kHz) sound waves that are above the insects ability to detect Counter-counter-counter adaptation = moths have sensors that detect wind movement created when bats hover for an instant prior to striking prey – gives moth a chance to quickly drop to ground Right now bats are developing ???