The study of spacing patterns in animals is a field in which ecology and ethology complement each other. Spacing is brought about to a considerable degree by the manner in which different individuals of a species react to each other, and it has important effects on the population dynamics, popula­ tion genetics, and evolution of species. The dispersion of animals in space and time results, in a proximate sense, from the direct response of individu­ als to features of the environment and to the presence or absence of other individuals of the species. This review will examine concepts of spacing patterns in mobile animals from the perspective of their proximate causes, their ecological consequences, and their adaptive significance.

Spacing Patterns in Mobile Animals

Summary
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.

On the definitions and functions of dominance and territoriality

The evolution of alternative male reproductive strategies in field crickets

The behavioral characteristics of territorial ungulates are reviewed and compared with non-territorial species in terms of social distribution, spatial dispersion, and interaction patterns. Territoriality is related proximally to dominance and ultimately to mating exhancement. Alternative male mating strategies are categorized. Selective gains are estimated by the potential mating enhancement factor (PMEF) and costs by reduced chances of survival. The likely lifetime mating enhancement (LLME) resulting from territorial versus roving/rank dominance strategies are calculated for model populations. Ecological conditions favoring territoriality are discussed, and a comparison is made with territorial systems in other animal groups. There is a need for more empirical data.

On Territoriality in Ungulates and an Evolutionary Model

8 – Sperm Competition and the Evolution of Odonate Mating Systems

[In dieser Arbeit wird versucht, beim terrestrischen Isopoden Venezillo evergladensis den relativen Beitrag zu schatzen, der nach Paarung eines Weibchens mit mehreren Mannchen hintereinander von diesen zu den resultierenden Mischungen gespeicherten Spermas geleistet wird. Mit Hilfe von drei die Farbmuster kontrollierenden Genloci lassen sich die Beitrage von 2-3 aufeinanderfolgenden Mannchen identifizieren. Mehrfache Besamung fuhrt zu Spermamischungen, bei denen das erste Mannchen groseren Befruchtungserfolg erzielt als das zweite und dritte, und das zweite einen groseren als das dritte Mannchen. Vorrangiger Befruchtungserfolg durch das zuletzt gekommene Mannchen existiert nicht. Jungfrauliche oder junge Weibchen bieten den Mannchen groseren Fortpflanzungerfolg, so das die Selektion zweifellos jede Fahigkeit der Mannchen begunstigen durfte, solche Weibchen zu erkennen. Die Vorteile der Spermamischung sind folgende: 1. Die Frequenz von Vollgeschwistern in der Nachkommenschaft eines Weibchens nimmt ab. Da Paarungen von Vollgeschwistern zu einer Minderung des Fortpflanzungserfolgs fuhren, bietet der Anteil von Halbgeschwistern an der Nachkommenschaft eines Weibchens die Moglichkeit, dem entgegenzuwirken. 2. Langandauernde Spermaspeicherung verbessert die Stabilitat von Polymorphismen. 3. Die effektive Populationsgrose ist groser, als es auf Grund der Anzahl lebender Individuen den Anschein hat. Dadurch verringert sich die Wahrscheinlichkeit von Auswirkungen von Gendrift., In dieser Arbeit wird versucht, beim terrestrischen Isopoden Venezillo evergladensis den relativen Beitrag zu schatzen, der nach Paarung eines Weibchens mit mehreren Mannchen hintereinander von diesen zu den resultierenden Mischungen gespeicherten Spermas geleistet wird. Mit Hilfe von drei die Farbmuster kontrollierenden Genloci lassen sich die Beitrage von 2-3 aufeinanderfolgenden Mannchen identifizieren. Mehrfache Besamung fuhrt zu Spermamischungen, bei denen das erste Mannchen groseren Befruchtungserfolg erzielt als das zweite und dritte, und das zweite einen groseren als das dritte Mannchen. Vorrangiger Befruchtungserfolg durch das zuletzt gekommene Mannchen existiert nicht. Jungfrauliche oder junge Weibchen bieten den Mannchen groseren Fortpflanzungerfolg, so das die Selektion zweifellos jede Fahigkeit der Mannchen begunstigen durfte, solche Weibchen zu erkennen. Die Vorteile der Spermamischung sind folgende: 1. Die Frequenz von Vollgeschwistern in der Nachkommenschaft eines Weibchens nimmt ab. Da Paarungen von Vollgeschwistern zu einer Minderung des Fortpflanzungserfolgs fuhren, bietet der Anteil von Halbgeschwistern an der Nachkommenschaft eines Weibchens die Moglichkeit, dem entgegenzuwirken. 2. Langandauernde Spermaspeicherung verbessert die Stabilitat von Polymorphismen. 3. Die effektive Populationsgrose ist groser, als es auf Grund der Anzahl lebender Individuen den Anschein hat. Dadurch verringert sich die Wahrscheinlichkeit von Auswirkungen von Gendrift.]

Multiple insemination and sperm storage in the isopod, venezillo evergladensis schultz, 1963

Species identification in the eastern Crematogaster (Hymenoptera: Formicidae).

The purpose of this paper is to outline the characteristics and possible origin of odonate territoriality. Sufficient data have accumulated from studies of about 12 species to develop a preliminary concept of the behavior's origin. Direct evidence of genetically fixed behavior is not available for dragonflies but examination of ecological parameters gives indirect support for an innate basis of the traits associated with territoriality. Corbet (1952), Kormondy (1959), Johnson (1962a), and others have made estimates of adult longevity and death rate which indicate that a high percentage of adults die shortly after reaching maturity; thus, little time is available for the adult function of reproduction. This period is often further shortened by environmental factors which inhibit odonate activity. Any part of this time consumed in learning would further decrease the functional adult period. The attributes which make up breeding and territorial behavior have a specific stereotyped expression in all individuals of the same sex for a given species. For these similar, often complex, traits to arise independently through learning during the short adult life is unlikely. Repeated aggressive contacts between individuals often suggest that participants may learn to avoid areas where intensive intraspecific aggressiveness exists. This learned behavior is similarly expressed in different species. From the ecological considerations given above, species-specific behavior is assumed to be genetically controlled unless adult traits are learned very rapidly or partly prior to the adult stage, possibilities which have no support among Odonata. Territoriality must have developed therefore through selection for advantages conferred on individlak.l. CHARACTERISTICS AND ADVANTAGES OF TERRITORIALITY

The evolution of territoriality in the odonata

This study reports the species of five families of terrestrial isopod crustaceans (oniscoids) from Florida. Twelve species including three each of Tylos and Ligia and one each of Ligidium, Vandeloscia, Sayoscia, Rhyscotus, and a new genus, Floridoscia (with a new species), are included. Another common species from Florida. Philoscia floridana Van Name. is placed in a new genus, Ocelloscia. Illustrations, notes on habitat, and distribution maps are included for all 12 species.

Terrestrial Isopod Crustaceans From Florida (Oniscoidea). Tylidae, Ligiidae, Halophilosciidae, Philosciidae, and Rhyscotidae

This paper reports sex ratios in individual sibships and in adult populations, the effects of inbreeding and the likely interaction of these features on fitness in the isopod, Venezillo evergladensis. Sex determination in terrestrial isopods has proved difficult to explain. The large number and small size of the chromosomes (2N = 54 in Armadillidium nasatum) have prevented recognition of specific sex chromosomes (Teichmann, 1962). Some workers have argued for heterogametic females, still others for heterogametic males though all arguments have been based on indirect evidence. Much of the evidence is reviewed by Bacci (1965) . The isopod literature recognizes three female types, amphogenics producing broods with 1 : 1 sex ratios, thelygenics, and arrhenogenics producing broods with higher proportions of females and males respectively. The term, monogeny, simply denotes the presence of either of the latter two female types. The cause of monogeny in the progenies of different females may well provide an insight to the relative fitness between amphogenic and monogenic females. The first serious attempt to identify the causative mechanism dates back to Vandel (1938). Judging from a series of breeding studies in France on the genera Trichoniscus and Armadillidium, Vandel (1938, 1939) explained monogeny as a response to a 'cytoplasmic factor transmitted by females. The factor's presence could presumably override the nuclear role of sex determination. Howard (1940, 1942, 1958) continued inquiries by breeding studies using Armadillidium vulgare. He obtained lines breeding true for amphogeny and thelygeny and found evidence for a maternal influence, though a paternal effect on the daughter's type could not be excluded. He also found sibship size between female types did not vary in a meaningful way and was unable to explain the absence of one sex by differential mortality prior to scoring. More recently, Juchault and Legrand (1970, 1972) and Legrand and J uchault (1972) provided convincing evidence for cytoplasmic factors having self reproducing, infective properties that act to modify the sex ratios. These investigators experimentally converted females from amphogeny to thelygeny, and the case is similar to the spirochete-like particle affecting sex ratios in Drosophila willistoni (Poulson and Sakaguchi, 1961). Amphogenic females are free of the particles. It is not clear whether thelygenics and arrhenogenics reflect different particles or a genetically different response to the same particle. Laboratory breeding data reveal high frequencies of monogenic females and thus indirectly attest to high frequencies of such females in the populations providing the breeding stocks. Such data for V. evergladensis are given below. Samples of females taken directly from nature have infrequently been scored by the sex ratios of their offspring. Vandel (1938, 1939) found 41 arrhenogenies and 32 thelygenics in a sample of 88 females of Trichoniscus provisorius, and four each of these two types in 15 females of Armadillidium vulgare. Nine of 30 gravid females of the latter species I collected in Gainesville, Florida, produced broods, exceeding 68 young per brood, departing from 1 : 1 ratios at the .05 probability level, 4 and 5 having greater female and male numbers respectively. Thus, monogeny occurs in a frequency capable of playing a significant role in

Clifford Johnson

Papers

Multiple insemination and sperm storage in the isopod, venezillo evergladensis schultz, 1963

Species identification in the eastern Crematogaster (Hymenoptera: Formicidae).

The evolution of territoriality in the odonata

Terrestrial Isopod Crustaceans From Florida (Oniscoidea). Tylidae, Ligiidae, Halophilosciidae, Philosciidae, and Rhyscotidae

Evolution of sex ratios in the isopod, venezillo evergladensis.