What Shapes an Ecosystem? Ch. 4-2 Ecology Notes 4 What Shapes an Ecosystem? Ch. 4-2

1. Symbiotic Relationships SYMBIOSIS – Biological relationship where 2 organisms live in close association. There are 3 main types: PARASITISM – Parasite benefits from host and host is harmed Example: LEECHES ON HUMAN SKIN COMMENSALISM - One organism benefits and the other is not harmed Example: REMORA EATING PARASITES OFF SHARKS MUTUALISM – Both organisms benefit from an association Example: CLOWN FISH & SEA ANEMONE (clown fish live in the anemone and in return frighten off organisms that may harm the anemone)

Clown Fish & Anemone 

2. Predation PREDATION – a predator captures and eats prey PREDATOR – captures, kills and consumes another organism PREY- organism that is eaten PREDATION IS DIFFERENT FROM PARASITISM Parasites seek to use their hosts as long as possible (goal is not to kill, just use) Predators remove prey immediately from an ecosystem

Predation Drives Evolution Predators adaptations locate & subdue prey Prey adaptations elude & defend Predation provides a strong selection pressure on both prey & predator horns, speed, coloration spines, thorns, toxins Predation provides a strong selective pressure on prey populations. Ay feature that would decrease the probability of capture should be strongly favored.

Defense Mechanisms Camouflage whipporwill frog lizard lizard toad

Warning “Aposematic” Coloration Bright warning to predators

Mimicry green parrot snake hawkmoth larvae Palatable or harmless species mimics a harmful model green parrot snake Hawkmoth larva puffs up to look like poisonous snake hawkmoth larvae

Mimicry Monarch male poisonous Viceroy male edible

3. Competition Competition – The “FIGHT” for an area’s resources. There are 2 types: INTERSPECIFIC – members of two different species compete Example: TWO TYPES OF BIRDS EATING THE SAME BUGS INTRASPECIFIC – members of the same species compete Example: 2 STUDENTS VYING FOR A PARKING SPOT A NICHE reduces competition All organisms have different ways of life. A species’ individual lifestyle is its niche (role in the environment).

The Niche Cape May Warbler Feeds at the tips of branches near the top of the tree Bay-Breasted Warbler Feeds in the middle part of the tree Spruce tree Yellow-Rumped Warbler Feeds in the lower part of the tree and at the bases of the middle branches

3. Competition Niche Overlap When organism niches overlap, competition occurs An organism will either evolve or die to reduce competition COMPETITIVE EXCLUSION– one species competing for a limited resource is removed from a community due to its inability to compete with other species Natural Selection favors the evolution of differences between competitors CHARACTER DISPLACEMENT– evolution of niche differences or physical variations that lessen competition Example: Galapagos finches living on the same island have different shaped beaks so all access different food sources RESOURCE PARTITIONING – Use of only part of a resource so as to avoid competing with an organism in need of the same thing Example: The text discusses 3 species of warbler that eat the same things but feed in different regions of a tree.

Niche & Competition Competitive Exclusion No two similar species can occupy the same niche at the same time

Symbiosis mutualism +/+ commensalism +/0 predation +/- competition -/-

4. Properties of Communities SPECIES RICHNESS – the number of types of species in an ecosystem Indicates ecosystem health when high High biodiversity also increases the chance that life will continue in an ecosystem even after some type of disaster Two Distinct Patterns HIGH RICHNESS CLOSER TO THE EQUATOR The theory suggests that more organisms exist in tropical habitats because they are stable in temperature Tropical habitats are also “younger” and probably have not been impacted as severely by past Ice Ages SPECIES AREA EFFECT Larger land areas support higher numbers of species Habitat destruction decreases the diversity of species in an area

4. Properties of Communities SPECIES DIVERSITY – the abundance of each type of species in an ecosystem Indicates the importance of a particular species High numbers of a particular organism suggests that it performs an important function for the ecosystem COMMUNITY STABILITY - Stability of a community is its resistance to change. High species richness suggests greater INTERDEPENDENCE of organisms Increased links between organisms equals increased reliance and increased stability of an ecosystem

5. Ecological Succession SUCCESSION – the gradual growth and re-growth of an ecosystem Disturbances in an ecosystem affect its growth patterns and development As an ecosystem recovers from a disturbance it experiences recognizable sequences of re-growth. There are 2 main types of succession: PRIMARY SUCCESSION – development of a community that has never been inhabited before PIONEER SPECIES – The first species to inhabit an area SECONDARY SUCCESSION – re-growth of a community following natural disaster or human interference CLIMAX COMMUNITY – a community having successfully gone through stages of succession to reach a stable endpoint A Climax Community remains constant for a long period of time…at least it hopefully should!

Primary Succession pioneer species compete well in high sunlight lichens & mosses grasses more shade tolerant species climax forest shade tolerant species stable community bushes & small trees trees

Secondary Succession burning releases nutrients formerly locked up in the tissues of tree the disturbance starts the process of succession over again