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What are the four concepts of evolution?

genetic drift
gene flow
gene pool

i think.


Define ecosystem diversity

variety of ecosystems present in a place or geographic area
-deserts, grasslands, wetlands, and forests

supports proper ecosystem functioning
-provides services such as flood control
-protection from soil erosion
-air and water filtering


What are the physical characteristics of an ecologically diverse environment?

ecosystem diversity/composition
biological community
organisms' impact on the physical environment
limiting resources


Define biological community

species that occupy a certain place and their interactions


Define ecosystem

community plus physical and chemical features of the environment

-species composition depends on sp. interactions and physical environments


Define limiting resource

any component of the niche that restricts population size

ex. roosting sites, soil nitrogen

-can include successional stage


Define succession

change in the species composition in a biological community


How does the physical environment impact ecosystem diversity?

determines whether a site will be a forest, grassland, desert, wetland, etc.

terrestrial communities: depends primarily on temperature and precipitation

aquatic communities: depends primarily on light and oxygen


How can organisms affect their physical environment on a small scale?

wind speed, humidity, temperature

eg. more humid and constant temperature within a forest because of the plants.


Define species interactions and name its subcatergories

defined in terms of positive and negative effects on participants

mutualism, competition, predation


What is mutualism? (also symbiosis)

interaction in which both species benefit

flowering plants and pollinators

losing one participant can endanger the other

Symbiosis: extreme mutualism in which participants cannot survive without each other (ex. lichen = fungus + alga)


What is competition?

interaction with negative effect for both species

may be a problem with introduced species


What is predation?

interaction with a positive effect on one species and a negative effect on another

may indirectly affect the number of prey species
-keeps density of each low enough to prevent competitive exclusion
-ex. Pisaster (sea star) feeds on 15 sp. of mollusks, prevents one or two sp. from being dominant


Name the trophic levels

primary producers
primary consumers
secondary consumers
tertiary consumers (ETC up to 7 levels)
and detritivores


What are primary producers?

photosynthetic species that obtain energy directly from sun to build organic molecules necessary for growth

-higher plants in terrestrial communities
-single cell algae and cyanobacteria (blue-green algae) in aquatic communities


What are primary consumers


eat photosynthetic species

only small percentage of energy transferred to herbivore level (about 1/2)
-respiration of photosynthetic species
-much plant material is indigestible


What are secondary consumers?

carnivores, predators

eat herbivores


What are tertiary consumers?

secondary carnivores

eat carnivores


What are detritivores?

species that feed on dead plant and animal tissues and wastes

-break down complex tissue and organic molecules
-release minerals back into environment where can be taken up again by primary producers (nitrates, phosphates)
-usually fungi and bacteria, includes vultures and other scavengers, dung beetles, earthworms


What are parasites, pests, and pathogens in relation to trophic levels?

a subclass of secondary consumers (predators)

protozoa, fungi, bacteria

plants (mistletoe)

animals (tapeworms, mosquitoes)

trophic levels linked through food webs.


What are keystone species?

species that determine the ability of large numbers of other species to persist in the community


Four types of keystone species

top predators that control herbivore populations
-gray wolves

pollinators and seed dispersers
-flying foxes in old world tropics and pacific islands

species that modify physical environments
-beavers, leaf cutter ants

continuous food producers
-fig trees


What happens when a keystone species goes extinct?

an extinction cascade= series of linked extinction events


What happens when we try to restore keystone species?

other species and aspects of the physical environment (soil cover) may already have been lost and are irreplaceable.


What are keystone resources?

resources that are crucial to many species in the community

may occupy only a small portion of a conservation area


What are examples of keystone resources?

salt licks and mineral pools (provide essential minerals)

deep pools in streams and springs
-refuge for fish and aquatic sp. during dry season
-refuge for terrestrial animals as drinking water

hollow tree trunks
-breeding sites for many bird and animal species