6. Non-Adaptive Radiation Flashcards
What are non-adaptive radiations?
Species try to occupy the same ecological niche in different locations.
Define non-adaptive radiations according to Gittenberger, 1991.
Rapid speciation resulting in many species that lack accompanying phenotypic diversification.
What is relevant niche differentiation?
Species must co-exist in sympatry and have no strong evolutionary differences.
What does relevant niche differentiation imply about species differences?
Differences are driven by random processes, not selective pressure.
Provide an example of non-adaptive radiations.
Achatinellidae land snails of Hawaii.
What is a characteristic of species in non-adaptive radiations?
They have no significant adaptive differences despite variations.
What did Rundell and Price (2009) say about island monarch flycatchers?
They are allopatric replacements of each other with similar functionality.
Describe the Albinaria land snails of Greece and Turkey.
Diversified in shell and genitalia traits, but with no apparent niche differentiation.
What does the South American Sigmodotine rodent radiation illustrate?
Random divergence in mandible traits with no adaptive correlation to the environment.
What is the significance of woodland salamander, Plethodon?
Illustrates a burst of speciation with high levels of niche conservatism.
What is the divergence pattern in Old World Leaf Warblers?
Diverged into rough groups with high plumage and morphological similarity.
What characterizes the Zosteropidae radiation?
Rapid diversification across a broad geographical area with ecologically similar species.
What are intrinsic traits that contribute to high diversification rates in Zosteropidae?
- Dispersal ability
- Generalist ecologies
- Sociality and flocking behavior
- Short generation time
- Capacity for rapid morphological shifts
How do adaptive and non-adaptive radiations relate?
They may be better thought of as a spectrum.
What did Tetragnatha spiders illustrate regarding adaptive and non-adaptive radiations?
They have undergone both adaptive and non-adaptive radiations.
What are the five scenarios of trait divergence in reproductive capability vs. resource acquisition?
- Ecological speciation in allopatry
- Ecological speciation begins in allopatry but collapses in sympatry
- Non-ecological speciation in allopatry with extinction in sympatry
- Non-ecological speciation in allopatry with character displacement in sympatry
- Non-ecological speciation in allopatry with species persistence in sympatry
What can mitigate competitive exclusion among species in non-adaptive radiations?
- Micro-allopatry
- Intraspecific aggregation
- Priority effects
- Top-down limitation by species-specific enemies
What leads to adaptive radiation?
Repeated rounds of ecological speciation.
What leads to non-adaptive radiation?
Repeated rounds of non-ecological speciation.
What is the relationship between adaptive radiations and ecological processes?
Many adaptive radiations likely have a combination of ecological and non-ecological processes.
