Catastrophic Selection as a Factor in Speciation

Quantum speciation in Aegilops : Molecular cytogenetic evidence from rDNA cluster variability in natural populations

“…speltoides population, which is most probable, then it is possible to presume that rapid quantum speciation took place. It implies a new species originating as a new structural homozygote in a small, ecologically marginal population on the periphery of the parent species (3,7,8). One of the main characteristic features of this type of speciation is the absence of a hybrid zone surrounding the area of the occurrence of the two species due to the strong genetic isolation of the neospecies observed in the studied populations.…”

“…Here, we will present molecular cytogenetic evidence supporting the model of quantum speciation by chromosomal repatterning in the genus Aegilops. Quantum speciation implies rapid origination of a new species in a small, ecologically marginal population on the periphery of the parent species area (3,7,8).…”

Ecological Genetics of the Wild Rabbit in Australia. III. Comparison of the Microgeographical Distribution of Alleles in Two Different Environments

“…The amount of protein and chromosomal variation found in central and marginal populations of plants and animals has been measured in several species (Carson 1959;Lewis 1962;Prakash 1973;Ayala and Tracey 1974). These results have generated a theoretical discussion concerning the genetical and evolutionary significance of differences in the life histories of different populations of a species living in different environments (e.g.…”

Evolutionary analysis of five bryophyte families using virtual fossils

“…It could signal any isolation event, sometimes followed by phenotypic stasis of the isolated population, resulting in a surviving ancestor. Identification of a surviving ancestor as a kind of living fossil may be done by (1) identification of a geologic fossil with an extant taxon; (2) biosystematic and cytogenetic studies, particularly in the case of "quantum" or local evolution (Lewis, 1962;Grant, 1971;Levin, 2001), the budding of a descendant species from a peripheral ancestral population, which are identifiable, for instance, as in the event of apparent daughter species being all more similar to an apparent parent than to each other; (3) the recent method of Theriot (1992) inferring a surviving ancestor in a group of diatoms by evaluating a morphologically based cladogram and biogeographical information; (4) the somewhat more simplistic and problematic selection of a surviving ancestor as one lacking autapomorphies on a polytomous morphological clade (Wiley & Mayden, 2000: 157; discussion by Zander, 1998); or (5) the method of virtual fossils used here.…”