Showing papers by "University of Winnipeg published in 1982"

Why asymmetric mating preferences may not show the direction of evolution.

Abstract: Recently, Kaneshiro (1976) and Watanabe and Kawanishi (1979) proposed models for determining phylogenetic direction when asymmetric mating preferences exist. Unfortunately, these authors reached completely opposite conclusions. Kaneshiro (1976, 1980) assumes that elements of courtship behavior are lost during founder events due to the associated genetic revolution and severe drift conditions. Females of the derived (new) species could thus recognize and accept the courtship of males of the ancestral (old) species while ancestral females would show more discrimination against derived males because those males would perform only a portion of the total courtship pattern of conspecific males. Watanabe and Kawanishi (1979), on the other hand, argue that \"A newly evolved species would have a small population size and would be exposed to the danger of mixing with the original species. If the newly evolved females mate with the original males, depletion of the new population results, But if a male of the new population mates with a female of the original population, he may mate again with a female of the new population; therefore, the new population is not adversely affected. Genes introduced from the new population into the old will soon be eliminated from the original species by normalizing selection.\" Following a test of both models on new data, Wasserman and Koepfer (1980) reported \"neither model can be considered reliable for determining phylogenetic direction.\" Similarily, Markow (1981) found no relationship between mating preference and the direction of evolution. The purpose of this commentary is to draw attention to an intrinsic flaw in both models, which was overlooked by their originators and by Wasserman and Koepfer (1980) and Markow (1981) who fault the models chiefly for their failure to adequately explain the authors' particular data set rather than for problems pertaining to the biological realism (or lack thereof) of the models themselves, These models ignore the fact that ethological isolating mechanisms may involve characters which are subject not only to reinforcing selection for reproductive isolation but in addition to other selective pressures unrelated to courtship and mate preference. These other selective pressures are unlikely to have any relationship to the phylogenetic status of the species, i.e., whether it is derived or ancestral; however, they may significantly enhance or diminish a character's effectiveness in courtship and mate recognition. Two examples from the literature on the stickleback, Gasterosteus aculeatus, illustrate the point. Both cases concern species which have yet to be formally described but whose biological validity has not been challenged (Moodie, 1972a; Bell, 1976). The first example (McPhail, 1969) is particularly appropriate because it was also used by Kaneshiro (1980) to support his model. I would argue that full consideration of McPhail's study casts doubt on the validity of both models. McPhail (1969) described a derived stickleback in Washington in which the typical red nuptial color of male G. aculeatus is replaced by black coloration. Hagen et al. (1980) showed the black coloration is the result of selection for convergence on the threat display of a sympatric species, Novumbra hubbsi. McPhail (1969) used mate preference tests to show that females from allopatric derived populations preferred red, ancestral males over black males from their own population. Mate preferences were asymmetric because ancestral females also preferred ancestral, red males. McPhail also determined mate preferences of derived females adjacent to a suspected hybrid zone. These females randomly chose derived and ancestral males. The behavior of the latter females differed significantly (P < .01) from that of allopatric derived females indicating initiation of the evolution of prezygotic isolation in sympatry. Female mate preference in the ancestral species, G. aculeatus, is known to be influenced by the presence of red nuptial color (pelkwijk and Tinbergen, 1937; Semler, 1971). Convergence on the threat display of N. hubbsi has resulted in the loss of red coloration in derived populations while at the same time, any selection acting on female choice has yet to eliminate the preference for the ancestral red nuptial color. The second example (Moodie, 1972a) concerns two populations in the Queen Charlotte Islands. One of these has a very restricted distribution and is morphologically distinct from the typical freshwater and marine sticklebacks found throughout the Pacific Northwest, The divergent population with its limited distribution can reasonably be considered the derived species but whether or not the typical freshwater stickleback with which it is parapatric is the ancestral species is uncertain. For this reason the typical, parapatric species will be referred to as \"ancestral (P).\" Female preference in the derived and ancestral (?) populations was tested using the design and statistical analyses of McPhail (1969). Table 1

The reproductive biology of an armoured catfish, Loricaria uracantha, from Central America

Abstract: The reproductive biology of one of the poorly known armoured catfishes, Loricaria uracantha, was studied in Panama. Natural nesting sites consisted of cavities in pieces of wood, open at both ends and positioned above the stream bottom, but artificial cavities of PVC pipe were readily used. Males possess bony bristles on the head and pectoral fins which contact the female prior to oviposition. Males spawned with up to five females in short succession and remained with the eggs until hatching. Following hatching many initiated another spawning cycle. One male was reproductively active for 73 days during which it completed five distinct reproductive cycles. Spawning extended throughout the year.

Spectral method of Boolean function complexity

Abstract: A common measure of Boolean function complexity is transformed to the Rademacher/Walsh spectral domain. The resulting spectral measure has an appealing visual interpretation not found in the functional domain. The relevance of this spectral measure to spectral translation and to the testability of certain classes of combinational networks is examined.

Analytical Chemical Applications of High-Resolution Nuclear Magnetic Resonance Spectroscopy of Solids

Abstract: The basis of the combined cross-polarization-magic-angle spinning (c.p.-m.a.s.) experiment, which yields high-resolution n.m.r. spectra of solid materials, is described and the general applicability of the technique, including its quantitative reliability, discussed. Solid-state n.m.r. is in many ways complementary to X-ray diffraction, as shown by its application to amorphous systems in which diffraction methods cannot be used (for example resins, coals, glasses and surface-immobilized catalysts) and also by its application to crystalline materials where X-ray structural data are available but where, for various reasons, a fuller description of the structure may be obtained by n.m.r. Examples include zeolites and chemically exchanging solid systems. The technique also provides a bridge between the solid-state structures of conformationally mobile and charged species as determined by diffraction techniques and the structures of these species in solution. Quantitative reliability of the c.p.-m.a.s. technique has been evaluated for phenolic resins and coals.

Neocortical versus whole-brain conceptions of personal death.

Abstract: Robert Veatch argues that the death of a person should be equated with the irreversible destruction of the cerebral cortex. This position is here questioned on grounds of tutiorism as well as on the basis of its philosophical assumptions. It is agrued that whole-brain death as an account of personal death is not open to these objections, and is a conception that can satisfy tutiorist standards of safety. The role of the EEG as an indicator of death is discussed.

Number of spectral coefficients necessary to identify a class of Boolean functions

Abstract: It is well known that only n+1 spectral coefficients, the Chow or modified-Chow parameters, are necessary to uniquely define any given linearly separable (threshold) function. It is here shown that n+1 coefficients only are necessary to define a much wider class of Boolean functions, namely all Boolean functions which can be realised from a threshold-logic core function with pre- and postlinear-translation operations. The use of n+1 spectral coefficients as a fault signature for all such functions is therefore possible.

Mesobates churchillensis n.sp., a new species of water mite from Churchill, Manitoba (acari: hygrobatidae)

Abstract: A new species of water mite, Mesobates churchillensis n.sp., is described. This is a first record for the genus from North America.

Capitalism and inequality: The negative consequences for humanity

Abstract: This paper has attempted to reveal the degree of inequality which exists within the capitalist world system among nations, among regions of nations, among classes, and among various sexual, racial, and ethnic groups. For themost part these inequalities are the direct and inevitable result of the “normal” operations of the capitalist mode-of-production. I have attempted to integrate an existant body of literature within a neo-Marxist theoretical perspective. By using such a perspective, I have attempted to document that inequality in the twentieth century is largely rooted in the capitalist relations of production and the normal machinations of the capital accumulation process. I have also tried to show that capitalist inequality is a major factor in determining the physical and psychological plight of the majority of the human race, particularly in the areas of life expectancy, infant mortality, morbidity, physical illness, mental illness, and so forth. The implications of such an analysis are profound and threatening to many. For equality of the human condition to become a reality, and thus for these negative human experiences to be significantly alleviated, would require, it would seem, a major restructuring of our most basic and taken-for-granted political-economic institutions and values. The sanctity of private property ownership would need to be drastically interfered with in order to bring about the qualitative improvement of the living conditions and experiences of the world's peoples. It seems to me that we would have to entertain the notion that private property ownership must be abolished and a social ownership and control of the commanding heights of the economy established as a first giant step towards a humane world.