Showing papers by "University of Alberta published in 1984"

Outgroup analysis and parsimony

Abstract: -Methods that use outgroups in the reconstruction of phylogeny are described and evaluated by the criterion of parsimony. By considering the character states and relationships of outgroups, one can estimate the states ancestral for a study group or ingroup, even when several character states are found among the outgroups. Algorithms and rules are presented that find the most parsimonious estimates of ancestral states for binary and multistate characters when outgroup relationships are well resolved. Other rules indicate the extent to which uincertainty about outgroup relationships leads to uncertainty about the ancestral states. The algorithms and rules are based on "simple parsimony" in that convergences and reversals are counted equally. After parsimony is measured locally among the outgroups to estimate ancestral states, parsimony is measured locally within the ingroup, given the ancestral states, to find the ingroup cladogram. This two-step procedure is shown to find the ingroup cladograms that are most parsimonious globally; that is, most parsimonious when parsimony is measured simultaneously over the ingroup and outgroups. However, the two-step procedure is guaranteed to achieve global parsimony only when: (a) outgroup relationships are sufficiently resolved beforehand; (b) outgroup analysis is taken to indicate the state not in the most recent common ancestor of the ingroup, but in a more distant ancestor; and (c) ancestral states are considered while the ingroup is being resolved, not merely added afterward to root an unrooted network. The criterion of global parsimony is then applied to evaluate procedures used when outgroup relationships are poorly resolved. The procedure that chooses as ancestral the state occurring most commonly among the outgroups can sometimes yield cladograms that are not globally parsimonious. By the criterion of global parsimony, the best procedure is one that simultaneously resolves the outgroups and ingroup with the data at hand. Finally, simple parsimony can choose among competing hypotheses, but it often fails to indicate how much confidence can be placed in that choice. [Phylogeny reconstruction; cladistic methods; outgroup analysis; character polarity; parsimony.] This paper explores the use of outgroup analysis in phylogeny reconstruction. When reconstructing a phylogeny, a systematist asks: Given a group of organisms (the ingroup), what are the monophyletic subgroups? If the members of a subgroup share a character state that is derived within the group, the monophyly of this subgroup is corroborated (Hennig, 1966; Wiley, 1975). Hence, systematists attempting to infer phylogenies have sought methods for determining whether a given character state is derived (apomorphic) or ancestral (plesiomorphic). Many methods for assessing the evolutionary polarity of characters have been proposed, including outgroup analysis, ingroup analysis, the ontogenetic method, and the paleontological method. These approaches have been reviewed recently by Crisci and Stuessy (1980), de Jong (1980), Stevens (1980), Arnold (1981), Nelson and Platnick (1981), and others. The methods perhaps most widely accepted today are outgroup analysis and the ontogenetic method, the relative merits of which are still being debated (contrast Nelson [1978] and Patterson [1982] with Lundberg [1973], Wheeler [1981] and Voorzanger and van der Steen [1982]). In its simplest form, outgroup analysis can be summarized by the following rule (Watrous and Wheeler, 1981): For a given character with two or more states within a group, the state occurring in related groups is assumed to be the plesiomorphic state. This rule is inadequate, however, when characters vary among the related groups (the outgroups). Arnold (1981) and Farris (1982) have dealt with some cases of

Persistence in models of three interacting predator-prey populations

Abstract: This paper considers a class of deterministic models of three interacting populations with a view towards determining when all of the populations persist. In analytical terms persistence means that liminft→∞x(t)> 0 for each population x(t); in geometric terms, that each trajectory of the modeling system of differential equations is eventually bounded away from the coordinate planes. The class of systems considered allows three level food webs, two competing predators feeding on a single prey, or a single predator feeding on two competing prey populations. As a corollary to the last case it is shown that the addition of a predator can lead to persistence of a three population system where, without a predator, the two competing populations on the lower trophic level would have only one survivor. The basic models are of Kolmogorov type, and the results improve several previous theorems on persistence.

A multidimensional approach to the relationship between mood and weather

Abstract: Ten mood variables were related to eight weather variables in a multidimensional study. Data were collected from 24 male subjects over 11 consecutive days. The mood variables were as follows: concentration, cooperation, anxiety, potency, aggression, depression, sleepiness, scepticism, control, and optimism. The weather variables included: hours of sunshine, precipitation, temperature, wind direction, wind velocity, humidity, change in barometric pressure and absolute barometric pressure. Humidity, temperature and hours of sunshine had the greatest effect on mood. High levels of humidity lowered scores on concentration while increasing reports of sleepiness. Rising temperatures lowered anxiety and scepticism mood scores. Humidity was the most significant predictor in regression and canonical correlation analysis. Implications for school and office performance are discussed which highlight the importance of humidity as a weather variable.

Induction of interleukin 2 messenger RNA inhibited by cyclosporin A.

Abstract: Cyclosporin A blocked production of the lymphokine interleukin 2 by activated T lymphocytes. In a human and a murine cell line this inhibition reflected an absence of interleukin 2 messenger RNA. Under conditions in which these cells are normally stimulated to secrete high levels of interleukin 2, they failed to do so in the presence of cyclosporin A. In both cell lines this failure was accompanied by an absence of interleukin 2 messenger accumulation.

The Psychology of Lineup Identifications1

Abstract: A review is made of issues and data on eyewitness identifications, and a relative-judgment conceptualization is proposed. It is argued that eyewitnesses are prone to choose the lineup member who most resembles the perpetrator relative to other lineup members as evidenced by studies that manipulated similarity of lineup members. The relative-judgment strategy is fallacious because of the unpredictable occurrence of target-absent lineups and is not corrected fully by instructions to eyewitnesses. An extension of the relative-judgment conceptualization proposes an inverse relationship between the goodness of witnesses' memories (quality and quantity of relevant information available in memory) and witnesses' tendencies to rely on relative judgments. This extended conceptualization was used to derive expectations regarding an experiment (N= 192 eyewitnesses) that used a blank lineup prior to presenting eyewitnesses with the actual lineup. The data indicated that a blank lineup can yield a diagnostic split of eyewitnesses; those who made no identification when presented with a blank lineup were less likely to make false identifications on the actual lineup than either the witnesses who identified someone from the blank lineup or the witnesses who were not presented with a blank lineup. The blank lineup did not produce a significant loss in accurate identifications. The practical implications of using blank lineups and the theoretical utility of the relative-judgment conceptualization are discussed.

Development Anatomy in Wheat of Male Sterility Induced by Heat Stress, Water Deficit or Abscisic Acid

Abstract: Well watered wheat (Triticum aestivum L. cv. Gabo) plants grown at 20°C were subjected to heat stress (30°C for 3 days), water stress (leaf water potential -2.54 MPa) or exogenous application of abscisic acid (ABA, 3 × 10-5 M) during meiosis in the pollen mother cells. All these treatments caused male sterility. The developmental anatomy of abortive anthers and pollen grains was studied using light microscopy. The anatomical events leading to pollen abortion in response to heat stress, water stress, and abscisic acid were generally similar. Three developmental sequences leading to sterility were identified. Type 1 was observed in response to heat stress and ABA. Premature tapetal degeneration resulted in periplasmodial invasion of the locule at meiosis and resulted in total sterility. Type 2 was observed in response to water stress when the microspores lost contact with the tapetum at first pollen grain mitosis (PGM I) and the filament degenerated. This also resulted in total sterility. Type 3 was observed in response to all three stresses and led to partial sterility. The microspores completed PGM 1 but a proportion became disoriented from the tapetum and developed no further. Each stress treatment resulted in two groups of abnormal anther locules, one completely sterile and the other partially sterile. Heat stress and ABA resulted in very similar abnormal development which differed only in the proportion of the two types (1 and 3). Water stress produced partial sterility through the same developmental pattern as heat stress and ABA (type 3). The sequence leading to total sterility in water stress affected anthers (type 2) was similar to that resulting in partial sterility (type 3). The results do not support the hypothesis that ABA is the single primary controlling agent in water stress induced sterility and the question of whether similar mechanisms lead to male sterility in response to the three treatments remains unanswered.

Report on Dialogue Specification Tools

Abstract: One of the goals of User Interface Management Systems (UIMS) is the automatic (or semi-automatic) construction of user interfaces. In order to accomplish this a description of the user interface to be implemented must be available. This report addresses three questions related to user interface descriptions. These questions are: what user interface descriptions are required to automatically produce a user interface, how do these descriptions relate to the human factors of user interfaces, and how can the existing user interface description techniques be classified? In order to address these questions an abstract model of a UIMS has been developed. This model does not represent how a UIMS should be’ structured or implemented, instead it presents the logical components that must appear in a UIMS. Each of these components has a different function, and different description techniques are required for each one. The logical model of a UIMS is shown in fig. 1. This model is similar to ones proposed by Edmonds [Edmonds 1982], Green [Green 1984], and Olsen [Olsen 1984]. Each of the components of this model will now be discussed.

Sex differences and social organization in free-ranging spider monkeys (Ateles geoffroyi)

Abstract: Several aspects of the social system of spider monkeys remain poorly understood in spite of previous studies of their behavior. Our work investigates sex differences of adultAteles geoffroyi to develop a better understanding of their social organization. A six-month field study of this species in Guatemala showed that adult males were both more aggressive and more socially cohesive than females, as well as more territorial. Adult females were more vocal, more submissive, more nonsocial, and more dispersed than adult males. Males were more likely to associate affinitively with other males than with females, and to direct their aggressive behaviors at females rather than males. Spider monkey society was found to be sex-segregated; males traveling and interacting in all-male subgroups, while females travel alone or with offspring. These findings are used, in conjunction with other evidence, to draw inferences about the dynamics of theAteles social system, and to derive an explanation for the evolution of spider monkey social organization. The frugivorous diet ofAteles is linked to the dispersion females and to the cohesion of related adult males, who form cooperative territorial groups, in which the low level of male-male competition is related to the absence of sexual dimorphism. Spider monkeys provide an illuminating contrast to the general primate model, derived from Old World monkeys, which links sexual dimorphism in size to sex differences in behavior, and ultimately to sexual selection.

Characteristics of Leg Movements and Patterns of Coordination in Locusts Walking on Rough Terrain

Abstract: A cinematographic analysis was made of locusts walking on a variety of terrains to determine the tactics used by single legs to find a site for support and the patterns of leg coordina tion when walking on rough terrain Three tactics were used by individual legs for finding a support site: (1)rhythmic searching movements initiated when the leg failed to contact the substrate at the end of the swing phase, (2) a tactile reflex to lift the leg above an object contacted during swing phase, and (3) local searching movements once the leg had contacted a potential supporting surface Animals did not adopt rigid gaits when walking on rough terrains The wide range of stepping patterns was due mainly to variation in the timing of stepping in opposite legs of the same segment However, there was a tendency for the stepping movements of opposite legs to be either 180° out of phase or exactly in phase In- phase stepping of the middle legs was observed frequently when animals walked over a ditch or up onto an eleva

Causes of negative correlations between grain yield and grain protein concentration in common wheat

Abstract: In a study designed to investigate the nature and basis of the relationships between grain yield (GY) and grain protein concentration (GBC) in common wheat, 11 populations, including 4 homozygous-homogeneous and 7 heterozygous-heterogeneous populations, were evaluated in a space planted and a solid seeded trial. Analysis of yield and protein data from each population revealed that phenotypic and environmental correlations between GY and GPC were negative and highly significant, whereas genetic correlation was significant in only one of 7 segregating populations studied. These results suggested that the inverse relationships between GY and GPC, although phenotypically real, were not caused by genetic factors. It would appear that environmental factors, source-sink interactions, and dilution of protein by non-protein compounds were the major agents that caused undesirable associations between the two traits.

Nucleotide sequence of the ribulosebisphosphate carboxylase gene from Rhodospirillum rubrum

Abstract: The nucleotide sequence of a cloned DNA fragment encoding ribulose bisphosphate carboxylase from the purple non-sulfur bacterium Rhodospirillum rubrum has been determined. The deduced amino acid sequence of a 1398 nucleotide open reading frame exhibits weak overall homology to the sequences reported for analogous enzymes from cyanobacteria, algae and angiosperms. Thus knowledge of the sequence is useful in attempts to identify structural features of the enzyme which are essential to catalysis. The gene is flanked by nucleotide sequences similar to those implicated in the initiation of translation and termination of transcription in other bacteria.

Microhabitat-associated variability in survival and growth of subtidal solitary ascidians during the first 21 days after settlement

Abstract: Newly settled juvenile ascidians were transplanted into shaded and unshaded sites at two subtidal depths to test the hypothesis that photonegative settlement behavior enhances juvenile survival. Silt, filamentous algae and grazing gastropods (Margarites pupillus) were identified as sources of mortality associated primarily with non-cryptic microhabitats. Silt inflicted heavy mortality on all six species tested. Algal overgrowth was important in shallow water, where it increased mortality and depressed growth rates over a 14-d period. Laboratory experiments demonstrated that gastropods can remove juvenile ascidians from the substratum. The sources of post-settlement mortality investigated may help determine distributional patterns of ascidians in the San Juan Islands, Washington, USA, and may also represent selective pressures that maintain negative phototaxis in the behavioral repertoires of ascidian tadpoles.