Generic distributional limits for measure preserving transformations

1984 ◽  
Vol 47 (2-3) ◽  
pp. 251-259
Author(s):  
Jon Aaronson ◽  
Benjamin Weiss
Keyword(s):  
Distributional Limits ◽  
Measure Preserving Transformations

scholarly journals MOLECULAR ZOOGEOGRAPHY OF FRESHWATER FISHES IN THE SOUTHEASTERN UNITED STATES

Genetics ◽  
1986 ◽  
Vol 113 (4) ◽  
pp. 939-965
Author(s):  
Eldredge Bermingham ◽  
John C Avise
Keyword(s):  
South Carolina ◽  
Southeastern United States ◽  
Population Subdivision ◽  
Positive Role ◽  
Level Change ◽  
Historical Factors ◽  
Length Polymorphisms ◽  
Amia Calva ◽  
River Drainages ◽  
Distributional Limits

ABSTRACT Restriction fragment length polymorphisms in mitochondrial DNA (mtDNA) were used to reconstruct evolutionary relationships of conspecific populations in four species of freshwater fish—Amia calva, Lepomis punctatus, L. gulosus, and L. microlophus. A suite of 14-17 endonucleases was employed to assay mtDNAs from 305 specimens collected from 14 river drainages extending from South Carolina to Louisiana. Extensive mtDNA polymorphism was observed within each assayed species. In both phenograms and Wagner parsimony networks, mtDNA clones that were closely related genetically were usually geographically contiguous. Within each species, major mtDNA phylogenetic breaks also distinguished populations from separate geographic regions, demonstrating that dispersal and gene flow have not been sufficient to override geographic influences on population subdivision.—Importantly, there were strong patterns of congruence across species in the geographic placements of the mtDNA phylogenetic breaks. Three major boundary regions were characterized by concentrations of phylogenetic discontinuities, and these zones agree well with previously described zoogeographic boundaries identified by a different kind of data base—distributional limits of species—suggesting that a common set of historical factors may account for both phenomena. Repeated episodes of eustatic sea level change along a relatively static continental morphology are the likely causes of several patterns of drainage isolation and coalescence, and these are discussed in relation to the genetic data.—Overall, results exemplify the positive role that intraspecific genetic analyses may play in historical zoogeographic reconstruction. They also point out the potential inadequacies of any interpretations of population genetic structure that fail to consider the influences of history in shaping that structure.

A Synchronic Perspective on the Grammaticalisation of will in Hypothetical Predicates

1996 ◽  
Vol 20 (2) ◽  
pp. 411-442 ◽  
Author(s):  
Debra Ziegeler
Keyword(s):  
Native Speaker ◽  
Small Sample ◽  
Semantic Constraints ◽  
Distributional Limits

Current works on grammaticalisation have discussed the tendency for older, lexically-based meanings to continue to adhere to the grammaticalising item in a situation described as 'retention' (Bybee & Pagliuca, 1987), and for these meanings to impose semantic constraints affecting the grammatical distribution of the item in some present-day environments. The present study will examine the restrictions on the use of the modal will (represented in its backshifted form would) in the hypothetical predicates of the verb wish, and, using a small sample of native-speaker informants, statistically-based suggestions will be proposed regarding the distributional limits on the grammaticalisation of the modal as a future auxiliary.

Orbit equivalence and actions of

2006 ◽  
Vol 71 (1) ◽  
pp. 265-282 ◽  
Author(s):  
Asge Törnquist
Keyword(s):  
Probability Space ◽  
Free Groups ◽  
Orbit Equivalence ◽  
Borel Probability ◽  
Free Actions ◽  
Measure Preserving Transformations

AbstractIn this paper we show that there are “E0 many” orbit inequivalent free actions of the free groups , 2 ≤ n ≤ ∞ by measure preserving transformations on a standard Borel probability space. In particular, there are uncountably many such actions.

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