ON THE DEFINITIONS AND FUNCTIONS OF DOMINANCE AND TERRITORIALITY

1. Dominance/subordinance is a relationship between two individuals in which one defers to the other in contest situations. Each such relationship represents an adaptive compromise for each individual in which the benefits and costs of giving in or not giving in are compared. Familiar associates in groups or neighbours on nearby territories may develop relatively stable dominant-subordinate relationships based on individual recognition. Although the aggressive aspects of dominance are usually emphasized, the less conspicuous actions of the subordinate individual are actually more important in maintaining a stable relationship. 2. In evolutionary terms, dominance essentially equals priority of access to resources in short supply. Usually the subordinate, who would probably lose in combat anyway, is better off to bide its time until better able to compete at another time or another place. Both individuals save time, energy, and the risk of injury by recognizing and abiding by an established dominant-subordinate relationship. 3. Dominance can be either absolute or predictably reversible in different locations or at different times. Of the various forms of dominance behaviour, rank hierarchies and territoriality represent the two extremes of absolute and relative dominance, respectively. A dominance hierarchy is the sum total of the adaptive compromises made between individuals in an aggregation or organized group. Many animals seem to be capable of both absolute and relative dominance, and within species-specific limits the balance may shift toward one or the other. High density, or a decrease in available resources, favours a shift from relative to absolute dominance. Some species may exhibit both simultaneously. Social mammals may have intra-group hierarchies and reciprocal territoriality between groups, while the males of lek species may exhibit ‘polarized territoriality’ by defending small individual territories, with the most dominant males holding the central territories where most of the mating takes place. 4. Territoriality is a form of space-related dominance. Most biologists agree that its most important function is to provide the territory holder with an assured supply of critical resources. Territoriality is selected for only when the individual's genetic fitness is increased because its increased access to resources outweighs the time, energy, and injury costs of territorial behaviour. 5. Territoriality was first defined narrowly as an area from which conspecifics are excluded by overt defence or advertisement. The definition has been variously expanded to include all more or less exclusive areas without regard to possible defence, and finally to include all areas in which the owner is dominant. I define territory as a fixed portion of an individual's or group's range in which it has priority of access to one or more critical resources over others who have priority elsewhere or at another time. This priority of access must be achieved through social interaction. 6. My definition excludes dominance over individual space and moving resources, and includes areas of exclusive use maintained by mutual avoidance. It differs from most other definitions in its explicit recognition of time as a territorial parameter and its rejection of exclusivity and overt defence as necessary components of territorial behaviour. There is an indivisible continuum of degrees of trespass onto territories, and functionally it is priority of access to resources that is important rather than exclusive occupancy. 7. There is a similarly indivisible continuum in the intensity of behaviour needed to achieve priority of access to resources. Deciding whether or not an exclusive area is defended leads to the pointless exercise of trying to decide which cues indicating the owner's presence are conspicuous enough to merit being called defence. Concentrating on overt defence emphasizes the aggressive aspects of territorial behaviour rather than the equally or more important submissive aspects such as passive avoidance.     

鹭鸶兰属的系统位置和起源

鹭鸶兰Ｄｉｕｒａｎｔｈｅｒａ Ｈｅｍｓｌ．为百合科的１个单种属。Ｄ．ｍｉｎｏｒ Ｈｅｍｓｌ．特产云南、四川和贵州。其植物形态、细胞学特征和化学成分均与吊兰属Ｃｈｌｏｒｏｐｈｙｔｕｍ的北缘种西南吊兰Ｃ．ｎｅｐａｌｅｎｓｅ Ｂａｋｅｒ和狭叶吊兰Ｃ．ｃｈｉｎｅｎｓｅ Ｂｕｒ．ｅｔ Ｆｒ．或大叶吊兰Ｃ．ｍａｌａｙｅｎｓｅ Ｒｉｄｌｅｙ极为接近或Ｃｈｌｏｒｏｐｈｙｔｕｍ ｍａｌａｙｅｎｓｅ进入云南高原气候比     

PROTEOKALON A NEW GENUS OF PROGYMNOSPERMS FROM THE DEVONIAN OF NEW YORK STATE AND ITS BEARING ON PHYLOGENETIC TRENDS IN THE GROUP

Proteokalon gen. nov. is described from the Upper Devonian Catskill deposits of New York. Two orders of branching and ultimate appendages are preserved' by petrifaction and by compression. The first order bears branches decussately and has a skewed four-armed protostele that occasionally dichotomizes. Second-order branches dichotomize rarely and most have T-shaped or three-armed protosteles. They bear ultimate appendages alternately, either in lateral pairs, or singly from the abaxial side. These appendages divide several times in one plane. Their vascular strand is terete. Maturation of the primary xylem is mesarch, and it consists of tracheids and parenchyma. Secondary xylem and phloem and a periderm are present. The outer cortex has a system of hypodermal fibers. Proteokalon is most similar to Tetraxylopteris and Triloboxylon of the Aneurophytales. A comparison of the stratigraphic occurrence of Protopteridium, Aneurophyton, Tetraxylopterism, Sphenoxylon, Triloboxylon, and Proteokalon suggests some evolutionary trends among the Aneurophytales.     

A PHYLOGENETIC ANALYSIS OF CHARACTER DISPLACEMENT IN CARIBBEAN ANOLIS LIZARDS

Twenty-seven islands in the Lesser Antilles contain either one or two species of Anolis lizards. On nine of the ten two-species islands, the species differ substantially in size; 16 of the 17 one-species islands harbor an intermediate-sized species. Two processes could produce such a pattern: size adjustment (or character displacement), in which similar-sized species evolve in different directions in sympatry; and size assortment, in which only different-sized species can successfully colonize the same island together. Previous analyses implicitly have assumed that size is evolutionarily plastic and determined solely by recent ecological conditions, and consequently have tested the hypothesis that character displacement has occurred on each of the ten two-species islands. Other studies have focused only on size assortment. By analyzing such patterns in a phylogenetic context, I explicitly consider historical effects and can distinguish between size adjustment and size assortment. Using a minimum evolution algorithm, I assess evidence for size adjustment by partitioning changes in size along branches of the phylogenetic tree. Size evolution appears rare (a minimum of 4-7 instances of substantial size evolution). In the northern (but not the southern) Lesser Antilles, size change was significantly greater when a descendant taxon occurred on a two-species island and its hypothetical ancestor occurred on a one-species island, thus supporting the size adjustment hypothesis, though size adjustment might have occurred only once. The relative rarity of size evolution suggests that size assortment might be responsible for nonrandom patterns. In both the northern and southern Lesser Antilles, a null model of no size assortment is convincingly rejected. Closely related taxa, however, are usually similar in size, and hybridization between species has been reported. Consequently, similar-sized species might not coexist because they interbreed and coalesce into one gene pool. A null model that only allows species from different “clades” to co-occur is rejected for the northern Lesser Antilles, but is ambiguous with regard to the southern Lesser Antilles. Thus, competitive exclusion is probably responsible for the pattern of size assortment in the northern Lesser Antilles; both competitive exclusion and interbreeding of closely related species of similar size might be responsible for the patterns evident in the southern Lesser Antilles.     

POLYPHENOLICS OF THE MARSILEACEAE AND THEIR POSSIBLE PHYLOGENETIC UTILITY

Species of the Marsileaceae represent a unique group of pteridophytes of uncertain origin. The polyphenolic profiles of representative species, which include flavonol-3-O-mono- and diglycosides, C-glycosylflavones and C-glycosylxanthones, have chemical features in common with the primitive leptosporangiate ferns, especially the Hymenophyllaceae. Intergeneric relationships in the family based on morphology, cytology, fossil evidence and polyphenolic profiles are discussed.     

PHYLOGENETIC ANALYSIS OF THE MARINE AND FRESHWATER THALAS-SIOSIROID DIATOMS

The thalassiosiroid centric diatoms are distinguished by at least one synapomorphy, the strutted process or fultoportula. Variously classified as a family (Thalassiosiraceae) or an order (Thalassiosirales) among centric diatoms, it is generally conceded that the group of several hundred fossil and living species is monophyletic as a whole. There are two ecological groups of thalassiosiroids, marine and freshwater. It has been hypothesized, based on an ecletic, non-rigorous, evolutionary taxonomy perspective that both the marine and freshwater ecological groups are also monophyletic, but this hypothesis has never been tested in a rigorous framework. Likewise, the freshwater thalassiosiroid species have been grouped into several genera and subgenera using an evolutionary taxonomic approach, but these hypotheses have not fully been tested using cladistic analysis. Focusing mainly on freshwater species, but including at least one representative of each marine genus and one representative from each of several proposed subgeneric groupings of the genus Thalassiosira , we scored morphological characters for fossil and living marine and freshwater Thalassiosiraceae to test these hypotheses. Our cladistic results provide strong support for monophyly for the freshwater group, but it seems unlikely that the marine group is monophyletic. The cladistic results are corroborated to greater or lesser degrees by the fossil record. The implications for evolution in the group and for taxon sampling in molecular studies we are conducting will be discussed.     

THE VASCULAR SYSTEM OF DOLEROTHECA AND ITS PHYLOGENETIC SIGNIFICANCE

The course of the vascular system in the proximal end of Dolerotheca formosa is described. Vascular bundles flare outward and downward immediately upon entering from the peduncle. These bundles are located in radiating septa just beneath the cover and give off small lateral bundles pinnately. Laterals from adjacent septal bundles meet, fuse, and extend downward in the parenchyma plate separating paired sporangia. The septal bundles, therefore, alternate in position with the parenchyma plate bundles and are interpreted as remnants of an ancestral bifurcating pinna system, which bore pendent sporangia along each side of supporting rachises. This interpretation differs from both the Codonotheca aggregation and plicated Whittleseya hypotheses recently advanced to explain the evolutionary pathway by which this complex pteridosperm pollen organ evolved.     

NULL MODELS FOR THE NUMBER OF EVOLUTIONARY STEPS IN A CHARACTER ON A PHYLOGENETIC TREE

Random trees and random characters can be used in null models for testing phylogenetic hypothesis. We consider three interpretations of random trees: first, that trees are selected from the set of all possible trees with equal probability; second, that trees are formed by random speciation or coalescence (equivalent); and third, that trees are formed by a series of random partitions of the taxa. We consider two interpretations of random characters: first, that the number of taxa with each state is held constant, but the states are randomly reshuffled among the taxa; and second, that the probability each taxon is assigned a particular state is constant from one taxon to the next. Under null models representing various combinations of randomizations of trees and characters, exact recursion equations are given to calculate the probability distribution of the number of character state changes required by a phylogenetic tree. Possible applications of these probability distributions are discussed. They can be used, for example, to test for a panmictic population structure within a species or to test phylogenetic inertia in a character's evolution. Whether and how a null model incorporates tree randomness makes little difference to the probability distribution in many but not all circumstances. The null model's sense of character randomness appears more critical. The difficult issue of choosing a null model is discussed.     

THE OPERCULA OF NERITOPSID GASTROPODS AND THEIR PHYLOGENETIC IMPORTANCE

The fossil record of neritopsid opercula and shells shows thatthe shell shape typical for Neritopsidae and Neritidae appearedin the Triassic. The ancestors of Neritimorpha were most probablyforms similar to Naticopsis. The operculum of Recent Neritopsisis composed of two calcitic parts secreted from inside and anaragonitic callus deposited from outside. Similar neritopsidopercula were already present in the Late Triassic. The firstopercula with asymmetrically situated muscle scars, possiblyancestral for neritids, also appeared at that time. (Received 27 May 2004; accepted 8 December 2004)