Term
| Classic (misleading?) conceptions of subterranean environment was considered |
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Definition
Simple
Isolated
Stable
Predictable
Nutrient Poor |
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Term
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Definition
| not simpler than surface environments; mosaic of individual microhabitats |
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Term
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Definition
| caves interconnected through fissures, cracks, MSS, etc |
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Term
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Definition
| more stable than surface but has annual and daily oscillations in different micro habitats |
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Term
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Definition
| equivalent to predictability on surface |
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Term
| Nutrient Poor environment |
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Definition
| main food reserves come from surface due to lack of photosynthesis |
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Term
| Subterranean environment was populated by a fauna that was |
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Definition
Living fossils
Relicts
No competition |
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Term
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Definition
such organisms must:
A. have survived long interval of geologic time in low numeric diversity
B. show primitive morphological characters; only Remipedia may be a living fossil
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Term
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Definition
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Term
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Definition
divided into 4 types
1. Numeric - rare survivors
2. Geographic - spread in a smaller geographic area
3. Phylogenetic - evolve at a very slow rate and have survived with few changes
4. Taxonomic - few close relatives
Living fossils must fit all 4 categories |
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Term
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Definition
| competition works at lower levels in caves due to lower density of animals |
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Term
| Common features of subterranean fauna |
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Definition
Regressive and convergent features
Predictive adaptations
Life cycle trends |
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Term
| Regressive and convergent features |
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Definition
also found in abyssal and soil fauna
1. depigmentation
2. loss of eyes |
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Term
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Definition
1. increased tactile and chemical sensitivity
2. increased metabolic economy
3. adaptations to moisture (terrestrial)
4. develpment of paedomorphic forms
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Term
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Definition
1. predominance of K (carrying capacity) selected vs. r (rapid reproduction), K selected best for cave animals due to relatively small amounts of food, in r boom is exceed carrying cap and bust is big dies off
2. longer duration of life cycle phases
3. tendency to direct development |
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Term
| Cave adaptations in Gammarus minus |
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Definition
| Adaptation by natural selection vs. neutral mutation and genetic drift (non-selective adaptation) |
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Term
| Advantage of regressed features (selection) |
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Definition
1. lessen injury or infections to eyes - no strong evidence and not valid for loss of pigment
2. energy economy - little evidence available |
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Term
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Definition
| in polygenetic systems where nearly all mutations are degenerative, time required to produce regressed features increases proportionally to the number of relevant genes |
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Term
| Effective population size and time of isolation of stygobites is what? |
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Definition
| consistent with neutral mutation but direct tests of the neutral hypothesis are not now possible |
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Term
| Are stygophiles better test organsims than stygobites? Why? |
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Definition
| Yes, they have extant populations in cave and surface habitats with a genetic connection between them |
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Term
| What has considerable variation between cave and surface forms? |
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Definition
| stygomorphic features (e.g. eyes, pigment, antennal length) |
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Term
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Definition
| stygophilic amphipod widespread in caves and springs in southern Appalachians |
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Term
| Requirements for a "complete adaptation explanation" |
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Definition
1. Heritability
2. Trait Polarity
3. Population Structure
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Term
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Definition
| examination of eye and antennal traits indicate they are heritable |
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Term
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Definition
| stygomorphic populations in caves resulted from an earlier invasion of subterranean habitats by morphologically unmodified surface forms |
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Term
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Definition
| stygomorphic population in upstream subterranean portion of the drainage are hydrologically connected with morphologically unmodified populations in the resurgence |
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Term
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Definition
| are genetically differentiated from cave populations in each basin |
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Term
| What does genetic clustering of cave populations by basin suggests? |
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Definition
| that cave colonization occurred independently in each basin |
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Term
| What do not appear to have occurred? |
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Definition
| Founder effect or population bottlenecks |
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Term
| Evidence for selection measure fitness in cave and spring populations by: |
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Definition
1. observing morphological features of amplexing (mating) and non-amplexing individuals
2. counting the # of fertilized eggs in brood pouch of females
3. ecological explanation of selection
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Term
| Selection in caves is for what? |
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Definition
| increased head length (body size) and antennal size, and decreased eye size |
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Term
| Selection in springs is for what? |
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Definition
| larger eyes, head length and antennal size |
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Term
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Definition
| size-selective predator of G. minus in springs |
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Term
| Overall selection gradients are what? |
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Definition
| consistent with the pattern of stygomorphic modification |
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Term
| What does ANOVA of eye selection gradients show between caves and springs? |
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Definition
| with caves and springs as groups (habitats) and particular cave and spring populations as subgroups (sites) indicates 94% of variance due to habitat difference within sites |
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Term
| Reduction of unused visual structures could improve what? |
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Definition
| fuctioning of extra-optic sensory systems by decreasing "noise" or increasing relative amount of CNS used by non-visual sensory systems |
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Term
What are antennal chemoreceptors needed for?
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Definition
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Term
| Larger antennae aid in what? |
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Definition
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Term
| Larger sized amphipods have higher what? |
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Definition
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Term
| Other cave organisms showing little morphological modification: |
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Definition
| they are usually associated with high energy food sources, e.g. guano |
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