Key terms
132 terms- Community§55.1
- All the species — plants, animals, fungi, protists, prokaryotes — that occur at one locality
- Species richness§55.1
- The number of species present in a community
- Primary productivity§55.1
- The amount of energy produced in a community
- Community composition§55.1
- Which particular species are present, as opposed to how many
- Individualistic view§55.1
- Species respond independently to conditions, so composition changes gradually over space and time
- Holistic community concept§55.1
- The alternative view that species function together as one integrated community unit
- Continuum§55.1
- A gradient along which one community merges into the next with no sharp boundary
- Ecotone§55.1
- A place where the environment changes abruptly, so many species shift abundance in synchrony
- Serpentine soil§55.1
- Soil high in nickel, chromium, and iron and low in copper and calcium; supports a distinct plant community
- Santa Catalina Mountains§55.1
- Arizona range where tree species abundances vary independently along a dry-to-moist gradient
- Paleontological evidence§55.1
- The 20,000-year fossil record showing past communities unlike any present community
- Niche§55.2
- The total of all the ways an organism uses the resources of its environment
- Fundamental niche§55.2
- The entire niche a species could use given only its physiological tolerances and resource needs
- Realized niche§55.2
- The actual conditions, including other species present, in which a species maintains a stable population
- Interspecific competition§55.2
- Competition between two species using the same resource when there is not enough for both
- Interference competition§55.2
- Physical competition over access to a resource, such as fighting or displacing an individual
- Exploitative competition§55.2
- Competition by consuming the same resources, won by the more efficient user
- Competitive exclusion§55.2
- If two species compete for a limited resource, the more efficient user eliminates the other locally
- Georgii Gause§55.2
- Russian ecologist whose 1934–1935 Paramecium experiments produced the exclusion principle
- Paramecium aurelia§55.2
- Gause species that grew about six times faster and drove P. caudatum extinct
- Paramecium caudatum§55.2
- Gause species eliminated by P. aurelia but able to coexist with P. bursaria
- Paramecium bursaria§55.2
- Gause species that fed on yeast in the low-oxygen bottom of the tube, allowing coexistence
- Joseph Connell§55.2
- Ecologist whose Scottish barnacle removals separated fundamental from realized niche
- Chthamalus stellatus§55.2
- Shallow-water barnacle whose realized niche is far smaller than its fundamental niche
- Semibalanus balanoides§55.2
- Deeper-water barnacle that outcompetes Chthamalus; its two niches are identical
- Hypericum perforatum§55.2
- St. John's wort, driven into shady refuges by an introduced beetle — predation shrinking a realized niche
- Pollinator decline§55.2
- Loss of insect pollinators that would shrink or erase the realized niche of many plants
- Resource partitioning§55.2
- Subdividing a niche so competing species use different portions of a resource
- Robert MacArthur§55.2
- Ecologist who showed five warbler species feed in five different parts of spruce trees
- Sympatric species§55.2
- Species that occur together in the same geographic area
- Allopatric populations§55.2
- Populations living where the other species does not occur
- Character displacement§55.2
- Selection driving sympatric species to diverge in resource use, reducing competition
- Morphology§55.2
- The form and structure of an organism
- Geospiza fuliginosa§55.2
- Darwin's finch with a beak like G. fortis when allopatric, different when sympatric
- Geospiza fortis§55.2
- Darwin's finch showing character displacement in beak depth where it co-occurs with G. fuliginosa
- Adaptive radiation§55.2
- Diversification of a lineage into many ecologically different species; promoted by character displacement
- Anolis lizards§55.2
- Caribbean lizards that partition trees by height, insect size, and thermal microhabitat
- Anolis gingivinus§55.2
- St. Maarten lizard that grows faster and perches lower when A. pogus is absent
- Anolis pogus§55.2
- St. Maarten lizard normally found near the ground; suppresses growth of A. gingivinus
- Kangaroo rat experiment§55.2
- 50 m × 50 m desert enclosures showing other rodents increase when kangaroo rats are removed
- Predation§55.3
- The consuming of one organism by another, including a deer grazing on grass
- Didinium§55.3
- Predatory protist that exterminates its Paramecium prey and then starves in simple culture
- Refuge§55.3
- A place prey can escape predators; prevents predator-driven extinction and allows recovery
- Predator–prey cycle§55.3
- Prey crash, then predator crash from starvation, then prey recovery
- White-tailed deer§55.3
- Eastern U.S. prey whose populations exploded after large carnivores were eliminated
- Stephens Island wren§55.3
- Bird driven extinct on one island by a single lighthouse keeper's cat
- Prickly pear§55.3
- Cactus that covered 12 million hectares of Australian rangeland by 1925 without predators
- Cactoblastis cactorum§55.3
- Argentine moth introduced from 1926 that controlled the Australian prickly pear by 1940
- Coevolution§55.3
- Adaptations selected in lockstep in two or more interacting species
- Evolutionary arms race§55.3
- Escalating cycle of prey defenses and predator counteradaptations
- Thorns, spines, prickles§55.3
- Plant morphological defenses that discourage large plant eaters
- Glandular hairs§55.3
- Sticky-tipped plant hairs that deter insect herbivores
- Silica§55.3
- Mineral deposited in grass leaves that strengthens them and makes them too tough to eat
- Wild tobacco signal§55.3
- Airborne chemical released on caterpillar attack that attracts a bug preying on the caterpillar
- Primary compounds§55.3
- Chemicals that are components of a major metabolic pathway such as respiration
- Secondary chemical compounds§55.3
- Structurally diverse plant chemicals that poison herbivores or disrupt their metabolism
- Mustard oils§55.3
- Pungent Brassicaceae secondary compounds; flavor cabbage and radish but poison many insects
- Brassicaceae§55.3
- The mustard family — mustard, cabbage, watercress, radish, horseradish
- Cardiac glycosides§55.3
- Milkweed and dogbane compounds with drastic deleterious effects on vertebrate heart function
- Asclepiadaceae§55.3
- The milkweed family, whose milky sap carries cardiac glycosides
- Apocynaceae§55.3
- The dogbane family, related to milkweeds and likewise chemically defended
- Pieris rapae§55.3
- Cabbage white butterfly whose caterpillars break down mustard oils and specialize on that family
- Monarch butterfly§55.3
- Species whose caterpillars store rather than break down cardiac glycosides from milkweed
- Sequestration§55.3
- Concentrating a plant toxin in fat bodies so it protects every later life stage, even the eggs
- Blue jay experiment§55.3
- Cage-reared jay eats a monarch, regurgitates it, and then avoids orange-and-black insects
- Poison-dart frogs§55.3
- Dendrobatidae, whose skin mucus carries more than 200 toxic alkaloids
- Alkaloids§55.3
- Toxic nitrogen compounds in dendrobatid skin, some now used in neuromuscular research
- Warning coloration§55.3
- Bright coloration advertising a genuine chemical defense; also called aposematic coloration
- Cryptic coloration§55.3
- Camouflage color that blends with the surroundings and hides an individual from predators
- Mimicry§55.3
- One species evolving to resemble another that carries an effective defense
- Batesian mimicry§55.3
- A palatable mimic resembling a distasteful, warningly colored model
- Henry Bates§55.3
- British naturalist who described palatable Amazonian mimics in 1857
- Mullerian mimicry§55.3
- Several unrelated but genuinely protected species converging on one warning pattern
- Fritz Muller§55.3
- German biologist who described mimicry among protected species in 1878
- Battus philenor§55.3
- Pipevine swallowtail — the poisonous model in the North American Batesian pair
- Papilio glaucus§55.3
- Tiger swallowtail — the palatable Batesian mimic, with polymorphic females
- Polymorphic females§55.3
- Tiger swallowtail females of several color forms, one closely resembling the pipevine swallowtail
- Heliconius§55.3
- Tropical butterfly genus whose sympatric species pairs are the standard Mullerian mimics
- Symbiosis§55.4
- Two or more kinds of organisms living together in elaborate, more-or-less permanent relationships
- Mutualism§55.4
- Symbiosis in which both participating species benefit
- Commensalism§55.4
- Symbiosis in which one species benefits and the other is neither helped nor harmed
- Parasitism§55.4
- Symbiosis in which one species benefits and the other is harmed
- Lichens§55.4
- Associations of certain fungi with green algae or cyanobacteria
- Mycorrhizae§55.4
- Fungus–root associations; the fungus speeds nutrient uptake, the plant supplies carbohydrates
- Root nodules§55.4
- Legume structures housing bacteria that fix atmospheric nitrogen for the host plant
- Leaf-cutter ants§55.4
- Tropical ants that farm fungi on chewed leaves rather than eating the leaves themselves
- Aphids§55.4
- Phloem-feeding insects that ants herd and milk for honeydew
- Honeydew§55.4
- Sugary excretion of aphids that tending ants consume
- Acacia§55.4
- Latin American tree genus whose hollow stipular thorns house Pseudomyrmex ants
- Pseudomyrmex§55.4
- Stinging ants that nest only in acacia thorns and defend the tree
- Stipular thorns§55.4
- Paired hollow modified leaf parts that serve as ant nesting chambers
- Beltian bodies§55.4
- Protein-rich structures at acacia leaflet tips that feed the resident ants
- Thomas Belt§55.4
- 19th-century British naturalist for whom the Beltian bodies are named
- Crematogaster nigriceps§55.4
- Kenyan acacia ant that prunes flowering tissue, turning mutualism into parasitism
- Ectoparasite§55.4
- External parasite that feeds on the exterior surface of the host
- Endoparasite§55.4
- Internal parasite living within the host body; usually far more specialized and simplified
- Parasitoid§55.4
- Insect that lays eggs in or on a living host whose larvae feed on and often kill it
- Dodder (Cuscuta)§55.4
- Parasitic flowering plant that lost chlorophyll and leaves and feeds on its host
- Dicrocoelium dendriticum§55.4
- Flatworm that manipulates ant behavior to reach its grazing-mammal host
- Host manipulation§55.4
- Parasite-driven change in host behavior that increases transmission to the next host
- Epiphyte§55.4
- Plant that grows on the branches of another plant, generally without harming it
- Spanish moss§55.4
- Tillandsia usneoides, a pineapple-family epiphyte on southern U.S. trees
- Clownfish§55.4
- Fish that lives unharmed among sea anemone tentacles and eats leftover food particles
- Oxpecker§55.4
- Bird that removes ticks from grazing mammals but also opens scabs and drinks blood
- Robert Paine§55.4
- University of Washington ecologist who removed Pisaster from intertidal plots
- Pisaster ochraceus§55.4
- Predatory sea star whose removal let mussels crowd out seven other species
- Mytilus californianus§55.4
- Mussel that monopolizes intertidal space when its sea star predator is removed
- Keystone species§55.4
- Species with an effect on community composition far greater than its abundance predicts
- Beaver§55.4
- Keystone engineer that converts running streams into impoundments and floods new areas
- Alligator holes§55.4
- Deep lake-bottom excavations that hold the only water during drought
- Tribolium§55.4
- Flour beetle genus in which an intracellular parasite reverses the competitive winner
- Lizard malaria§55.4
- Parasite to which the inferior St. Maarten Anolis is resistant, permitting coexistence
- Direct effect§55.4
- One species affecting another through immediate interaction, as rodents and ants over seeds
- Indirect effect§55.4
- One species affecting another through a chain running via a third species
- Rodent–ant experiment§55.4
- Rodent removal raises ant colonies at first, then lowers them as large-seeded plants take over
- Succession§55.5
- Communities changing from simple to complex over time even under a stable climate
- Primary succession§55.5
- Succession beginning on bare, lifeless substrate such as new rock or open water
- Secondary succession§55.5
- Succession where an existing community was disturbed but organisms still remain
- Pioneer species§55.5
- The first colonists of a barren habitat, which alter it so other species can invade
- Establishment§55.5
- The first successional concept: weedy r-selected colonists tolerating harsh abiotic conditions
- Facilitation§55.5
- Early species changing the habitat in ways that allow later species to colonize
- Inhibition§55.5
- New colonizers having negative effects on the species already present
- r-selected species§55.5
- Fast-reproducing weedy species that dominate early successional stages
- Glacier Bay§55.5
- Alaskan site where deglaciated ground shows lichen → moss → alder → spruce succession
- Alder§55.5
- Shrub with nitrogen-fixing symbionts that enriches soil nitrogen over about 100 years
- Spruce forest§55.5
- The late Glacier Bay stage that overtops and shades out the alders by about year 200
- Oligotrophic lake§55.5
- A lake poor in nutrients, the starting point of aquatic succession
- Eutrophic lake§55.5
- A lake rich in nutrients, produced as organic matter accumulates
- Disturbance§55.5
- An event that removes organisms and resets succession, locally or over a wide area
- Intermediate disturbance hypothesis§55.5
- Moderate disturbance yields higher species richness than very little or very much
- Light gap§55.5
- Rainforest opening from a fallen tree that starts its own successional sequence
- Climax community§55.5
- The supposed predictable successional end-state; no longer a widely accepted idea