Flashcards in Chapter 2 Deck (56)
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31
What are the four concepts of evolution?
selection
genetic drift
gene flow
gene pool
i think.
32
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
33
What are the physical characteristics of an ecologically diverse environment?
ecosystem diversity/composition
biological community
organisms' impact on the physical environment
limiting resources
34
Define biological community
species that occupy a certain place and their interactions
35
Define ecosystem
community plus physical and chemical features of the environment
-species composition depends on sp. interactions and physical environments
36
Define limiting resource
any component of the niche that restricts population size
ex. roosting sites, soil nitrogen
-can include successional stage
37
Define succession
change in the species composition in a biological community
38
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
39
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.
40
Define species interactions and name its subcatergories
defined in terms of positive and negative effects on participants
mutualism, competition, predation
41
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)
42
What is competition?
interaction with negative effect for both species
may be a problem with introduced species
43
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
44
Name the trophic levels
primary producers
primary consumers
secondary consumers
tertiary consumers (ETC up to 7 levels)
and detritivores
45
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
46
What are primary consumers
herbivores
eat photosynthetic species
only small percentage of energy transferred to herbivore level (about 1/2)
-respiration of photosynthetic species
-much plant material is indigestible
47
What are secondary consumers?
carnivores, predators
eat herbivores
48
What are tertiary consumers?
secondary carnivores
eat carnivores
49
What are detritivores?
species that feed on dead plant and animal tissues and wastes
-decomposers
-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
50
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.
51
What are keystone species?
species that determine the ability of large numbers of other species to persist in the community
52
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
53
What happens when a keystone species goes extinct?
an extinction cascade= series of linked extinction events
54
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.
55
What are keystone resources?
resources that are crucial to many species in the community
may occupy only a small portion of a conservation area
56
