Ecological Habits Research Articles

Comparisons of Growth in Weight of Temperate and Tropical Marine Fish Counterparts

For temperate and tropical marine teleosts I compared growth in mean weight with age with similar trophic positions and ecological habits. Temperate demersal forms generally grew faster than tropical counterparts whereas mesopelagic and pelagic forms were similar. I suggest that differences in growth rates may be related to higher metabolic costs in the tropics in comparison with temperate waters.

GRASSHOPPER MANDIBLES AND THE NICHE VARIATION HYPOTHESIS.

Evolutionary biology consists, in large measure, of attempts to understand biotic diversity. For this reason, the hypothesis (Van Valen, 1965) of adaptive variation occupies a central position among evolutionary theories. The hypothesis attempts to explain biotic diversity at both genetic and phenetic levels, postulating a causal relationship between genetic or morphological variation and ecological habits. Under the conditions of the hypothesis, populations that occupy broader ecological niches are expected to be more variable, in phenotype and genotype, than more narrow-niched populations (Van Valen, 1965). In the past, both continuous (unimodal) and discontinuous (polymorphic) variation have been considered as facets of a single process leading to adaptive variation. A variety of studies have examined the niche variation hypothesis. Tests of the hypothesis typically consist of estimates of genetic (i.e., electromorphic) or morphological variability in comparison with suitable estimates of ecological amplitude. In general, the results of these studies are ambivalent. While the electromorphic analyses of Shugart and Blaylock (1973) and Steiner (1977) generally support the niche variation model, others by Sabath (1974), Soule and Yang (1973), Powell and Wistrand (1978), Mitter and Futuyma (1979), and Smith (1981) provide conflicting, occasionally contradictory, results. Similarly, morphological analyses by Van Valen (1965), Grant et al. (1976), Davidson (1977, 1978), and Bernstein (1979) provide supporting evidence, while those of Soule and Stewart (1970), Soule (1972),

PRE-PARTUM REPRODUCTIVE CHARACTERISTICS OF EUTHERIAN MAMMALS.

A striking feature of reproduction in eutherian mammals is its limited diversity. All have internal fertilization, viviparity, and lactation. Most reproductive traits, including gestation time (Gunther and Guerra, 1955; Kilstrom, 1972; Sacher and Staffeldt, 1976), birth weight (Leutenegger, 1976; Millar, 1977; Robbins and Robbins, 1979), litter weight (Leitch et al., 1959), weight at weaning (Millar, 1977), and post natal growth (Gunther and Guerra, 1955; Millar, 1977; Case, 1978) are highly predictable from adult size. Only offspring number and duration of lactation appear poorly related to adult size (Millar, 1977). A general explanation for these relationships is that they are related to morphological and physiological constraints. Numerous physiological variables, including metabolic rate, are related to adult size (Gunther and Guerra, 1955; Stahl, 1967; Calder, 1974; Gunther, 1975; SchmidtNielsen, 1975). Structural traits are related to mechanical requirements so that they also are predictable from adult size (Huxley, 1932; Bonner, 1965; Gould, 1966). Together, these morphological and physiological patterns appear to influence ecological and behavioral patterns (Sacher, 1959; McNab, 1963; Lindstedt and Calder, 1976; Blueweiss et al., 1978; Harestad and Bunnell, 1979). The existence of a strong design constraint system in mammals presents problems when single traits are examined in relation to environmental conditions; foremost among these problems is that very few traits are independent of other traits. Characteristics not considered in any comparison can lead to biased results. In other words, changes in one trait may occur simply because another trait responds to environmental conditions. Another problem is that very few traits are linearly related to other traits so that the relative magnitudes of traits also vary predictably. Simple ratios cannot be used to compensate for these nonlinear relationships. These and other problems (considered in detail by Gould [1966] and Clutton-Brock and Harvey [1979]) have not always been recognized in studies of mammalian reproductive traits. The purpose of this study was to examine the interrelationships among reproductive traits of mammals in order to define the system of morphological and physiological constraints, and to examine the residual variation in this system in relation to taxonomic groups and ecological habits.

NOTES ON THE SOUTH AFRICAN SPECIES OF CORVUS

Summary Winterbottom, J. M. 1975. Notes on the South African spscies of Corvus. Ostrich 46:236-250. The three indigenous species of Corvus in South Africa are compared in respect of geographical and ecological distribution, status, breeding, food, economic importance and general habits. Apart from the limitation of range in albicollis by its nesting requirements, it is extremely difficult to pin-point any factors in which the species so differ as to explain the paradoxes of their distribution.

Evolutionary Adaptations of Haemoglobins

Abstract The properties of haemoglobin oxygen dissociation curves and the Bohr effect have, been studied in various poikiloterms animals living in different ecological conditions. The position of the curve and the direction and the intensity of the Bohr effect are perfectly correlated with the ecological habit of the organism under examination. Both these parameters are regulated by cofactors modifiyng the properties of the haemoglobin. An increase in the Bohr effect, probably with evolutionary adaptive value has been found in the indian peruvian population living from generation at high altitude. Also in this case the increase in Bohr effect is due to some factor presente in the red cell and different by the organic phosphates.

The biota of long-distance dispersal. I. Principles of dispersal and evolution.

A growing consensus of biologists now favors the effectiveness of long-distance dispersal as a means of populating islands. The observational and experimental bases on which this opinion rests are strong, but additional work is needed. A clear under-standing of long-distance dispersal is essential to an understanding of evolutionary trends on oceanic islands, because immigrant patterns are different from relict patterns. Since oceanic islands are short-lived, the evolutionary history of waif immigrants is also short. If a continental islands maintains long isolation, arrivals by long-distance dispersal may show evolutionary patterns more completely, as is true on New Zealand for example. The evolutionary patterns of waif biotas are influenced by isolation, by the broad range of available ecological opportunities, and, to a lesser extent, by the moderation characteristic of maritime climates. In addition to problems involved in becoming established, immigrants must overcome genetic disadvantages inherent in the fact that the number of original colonists is mall. Increase of genetic variability may be governed by ecological diversity, and persistence of a phylad may be increased by maximizing outcrossing and hybridization. Among features which are exhibited by waif biotas are adaptive radiation, flightlessness in animals, loss of dispersal mechanism in plants, and development of new ecological habits and growth forms. Each of these adaptations is evidently governed by a wide variety of factors. "Weedy" groups seem to possess the greatest ability to disperse and become established; they also excel at sensitive adaptation to island conditions. The waif biota contains few relicts except for "recent relicts."

A Seasonal Ecological Study of Foraminifera from Timbalier Bay, Louisiana

This study concerns the ecological habits of living Foraminifera from a shallow Louisiana coastal bay during a period of ten months. It is a part of an extensive study undertaken by the Coastal Studies Institute of Louisiana State University to determine the effect of chemical and physical properties of water upon marine life in a large, open bay over an extended period of time. Samples were collected monthly from established locations for the chemical, biological and foraminiferal determinations. Results of the chemical and biological studies will be published by the respective investigators in subsequent papers. The period of time covered by this portion of the study extended from January 1957 to October 1957. Unfortunately, the chemical and biological studies of the bay ended July 1957. Various chemical determinations which were considered pertinent to the study were continued by the investigator throughout the remaining time. Physical influences, such as geomorphology, hydrography and climate, are presented in this paper to help determine exactly what effects each had upon the living Foraminifera of the bay. The chemical data of the bottom waters, presented in Tables 20 to 29, are principally the results of the concurrent chemical study of the bay.

Oviposition Observations in Oncomelania formosana

Several workers have reported on field and laboratory observations on the life history of Oncomelania species, intermediate hosts of Schistosoma japonicum. Laboratory (Vogel, 1948) and field (Hsu, 1950) studies were made on 0. hupensis. F. C. Li (1934) gave an account of the ecology, among other aspects, of this Chinese species. Reports on 0. quadrasi are by Abbott (1946) and McMullen (1947). In recent years considerable work has been done on this snail in Leyte, Philippines (World Health Organization Reports). Observations on the reproductive habits of 0. nosophora are reported by Sugiura (1933), Ritchie et al (1951), McMullen et al (1951), Otori et al (1954, 1956). Roth and Wagner (1960) give an account of the production of eggs in 0. nosophora and 0. formosana, and Wagner and Wong (Chi) (1956) dealt with egg-laying in 0. nosophora and 0. quadrasi. Ecological habits of 0. formosana are reported by S. Y. Li (1953). Laboratory findings on the reproduction and growth of 0. quadrasi and 0. nosophora are given by Chi and Wagner (1957), with some data on 0. formosana. There are very few reports on the reproductive activities of 0. formosana and the present paper gives a more complete study of its reproductive habits.

Seasonal Ecological Study of Foraminifera from Timbalier Bay, Louisiana: ABSTRACT

Within the last decade, considerable attention has been directed toward understanding the ecological habits of Foraminifera. This study has ventured deeper than previous ones in an attempt to learn the habits of living Foraminifera in Timbalier Bay, Louisiana, over a period of a year. Ten monthly collections of samples were made from seventeen locations in the bay. Data relating to salinity, temperature, pH, eh, and other chemical and physical properties of the waters were recorded at this time. Upon examination of the samples, it was determined that twenty-three species of Foraminifera could be considered End_Page 1969------------------------------ common in the bay. Two facies zones were recognized within this polyhaline bay by the restriction of certain species to characteristic areas. Reproduction of the Foraminifera appeared to be dependent upon the environmental factors of salinity and temperatures. The use of water chemistry, other than salinity, to explain the reproductive habits of the Foraminifera was unsuccessful. Availability of nutrients is believed to be the principal cause of differences in total populations of living Foraminifera in the bay. These nutrients are probably derived from the land areas and transported around the bay by the normal water flow. Three periods of inflow of these materials into the bay were noted. There has been no comparable foraminiferal study of this bay. A recent foraminiferal study of several bays in Texas (Phleger and Lankford, 1957) is similar, but the periods between collections were longer, and no attempts were made to correlate the Foraminifera with the chemical properties of the bay. Myers (1943) studied the effects of food, substratum, depth, temperature, pH, oxygen tension, turbulence, turbidity, animal associations, parasites, and enemies of a single species, Elphidium crispum, over a period of a year. End_of_Article - Last_Page 1970------------

Some Nomenclatural Changes in the Genus Isoetes

the stress placed on the markings of the gynospores by Miss Pfeiffer in her monograph of the Isoetaceae2 has resulted in a rather distorted presentation of the relationships of the species is the conclusion reached by the author after a study of a wider range of morphological characters, of the ecological habits, and of the geographical distribution. Three species of this relationship are here recognized, all of which are distinct from the European I. echinospora Dur., with which they have frequently been united. The writer is indebted to C. A. Weatherby, C. V. Morton, and Joseph Ewan for suggestions.