Community Ecology Chapter 54

YOU MUST KNOW The difference between a fundamental niche and a realized niche The role of competitive exclusion in interspecific competition The symbiotic relationships of parasitism, mutualism, and commensalism The impact of keystone species on community structure The difference between primary and secondary succession

B. Fundamental niche – potential niche Niches A. Ecological niche – total of biotic and abiotic resources that a species uses in its environment B. Fundamental niche – potential niche C. Realized niche – the portion of the fundamental niche the species actually occupies Review inter- vs. intra-

II. Interspecific interactions A. Can be positive (+), negative (-), or neutral (0) Inter = between Intra = within Review inter- vs. intra-

B. Interspecific competition – for resources, -/- 1. Competitive exclusion– if two species compete for a niche, one wins, other goes extinct Review inter- vs. intra-

Predation – predator & prey, +/- 1. Cryptic coloration – camouflage 2. Aposematic coloration – warning Review inter- vs. intra-

3. Batesian mimicry – harmless species evolves coloration to 3. Batesian mimicry – harmless species evolves coloration to mimic the coloration of a harmful or unpalatable species 4. Mullerian mimicry – two bad-tasting species resemble each other so predators avoid them equally Review inter- vs. intra-

Herbivory – herbivores & plants, +/- 1. Selective advantage to animals that can recognize toxic plants 2. Selective advantage to plants that have protection like thorns, spines, and toxins Review inter- vs. intra-

Symbiosis – species live in direct contact with each other 1. Parasitism - +/- 2. Mutualism - +/+ 3. Commensalism - +/0 Plant roots and fungi

1. Dominant species – species with the highest biomass Community Structure A. Species diversity – number of different species (species richness) and relative abundance of each 1. Dominant species – species with the highest biomass Community with even species distribution is more diverse than one dominated by a couple species

Trophic structure – feeding relationships among organisms 1. Trophic levels – levels of organisms based on those relationship Rule of 10 – only 10% of energy from one level is available to the next level

2. Food chain – transfer of energy from one trophic level to the next

3. Food web – two or more food chains linked together

C. Keystone species – species that can impact all of the others in a community Pisaster –(starfish) keystone predator Review inter- vs. intra-

Review inter- vs. intra-

D. Invasive Species - typically introduced to a new environment by humans, often lack predators or disease Pythons Review inter- vs. intra- Zebra Mussels Cane Toads

Foundation Species - cause physical changes in the environment that affect community structure Beaver dams can transform landscapes on a very large scale Review inter- vs. intra- Kelp - provides shelter and suitable habitat for numerous other organisms

Succession – transition in species composition in an area over time A. Disturbances - Storms, fires, flood, drought, human activity 1. May remove organisms or change resource availability 2. Intermediate disturbance hypothesis – moderate levels of disturbances may foster species diversity Review inter- vs. intra-

1. Ex. colonization of a newly formed volcanic island Primary succession – living organisms gradually invade a region that was previously lifeless and without soil 1. Ex. colonization of a newly formed volcanic island Review inter- vs. intra-

C. Secondary succession – an existing community is cleared by a disturbance that leaves the soil intact Review inter- vs. intra-

Biogeography & Diversity A. Latitude – more diversity in tropics than near poles B. Land area – if all other factors are equal, the greater the area, the more diversity Review inter- vs. intra-

C. Islands – include actual islands and areas like national forests surrounded by development 1. Size of island - larger the island the higher the immigration rates and lower extinction rates 2. Distance to mainland– farther away from mainland, lower immigration rates and higher extinction rates Review inter- vs. intra-