Showing papers in "American Midland Naturalist in 1968"
TL;DR: Temperature and latitude are shown to be good predictors of body size in several species, but temperature does no better than latitude at predicting size.
Abstract: Techniques of statistical analysis are utilized to begin to unravel the causes involved in the evolution of body size clines in mammalian carnivores. Variables included are productivity, temperature, latitude, competitive pressure and size of potential prey. Temperature and latitude are shown to be good predictors of body size in several species. Indeed, they seem to be measures of the same cause, as has long been maintained by those attempting to explain Bergmann's rule. But temperature does no better than latitude at predicting size. Thus temperature is probably not a direct cause of Bergmann's rule in these animals. The measure of total primary productivity used (actual annual evapotranspiration, AE) proved to be one of the better corre- lates, especially at lower productivities. Apparently relatively meager food supplies set upper limits to, body size. Except in a very few cases, the biotic variables of competitive pressure and prey size were only second-rate predictors. Discussion of the patterns that have been shown by this analysis is included.
346Â citations
223Â citations
TL;DR: The high percentage of grazers in the fossil community suggests that interior Alaska was a grassland en- vironment during the late Pleistocene, leaving the comparatively depauperate community that exists in Alaska today.
Abstract: This study of the palcoecology of four fossil assemblages of large mammals from the late Pleistocene sediments near Fairbanks, Alaska, emphasizes the structure, composition, habitat, and the pat- tern of subsequent extinction of the community. All four faunas were composed predominantly of grazers. Bison, horse, and mammoth were the most common species. Many component species of this complex community of large mammals became extinct near the close of the Wisconsin glaciation, leaving the comparatively depauperate community that exists in Alaska today. The high percentage of grazers in the fossil community suggests that interior Alaska was a grassland en- vironment during the late Pleistocene.
161Â citations
TL;DR: The southern mixed hardwoods, mixed hardwood swamps, bayheads, sand pine scrub, sandhills, pine flatwoods, and cypress heads are the major forest community types in north central Florida.
Abstract: The southern mixed hardwoods, mixed hardwood swamps, bayheads, sand pine scrub, sandhills, pine flatwoods, and cypress heads are the major forest community types in north central Florida. The first three are climax communities (on upland, wet fertile, and wet acid sites, respectively) the latter four are successional. With improvement of drainage or the elimination of fire, succession may proceed in a variety of directions. The sandhill and scrub community types occur on dry sterile soils and are fire-maintained. Succession proceeds toward the southern mixed hardwoods. The pine flatwoods are fire-maintained and are on poorly drained soils. With release from fire, succession proceeds toward either of the three climaxes. The direction appears related to soil moisture and fertility. Cypress heads are limited by flooding. With improved drainage they may be converted to mixed hardwood swamps or bayheads depending upon soil fertility. An environmental similarity index, based on 11 variables, was calculated for the six community types as well as for 45 tree species that occurred in five or more stands. Three general groups of species are recognized: (1) successional, (2) climax pioneer, and (3) climax exclusive. The successional and climax pioneer are habitat generalists in that their environmental similarity indices are lower than that of the community types. Floristic continuity in large-scale vegetation is maintained by the presence of the habitat generalists while the element of discontinuity may be attributed to the climax exclusives. The mean of 11 variables for 45 tree species was used to position the species spatially. The spatial relationships relate the six community types without aberrant transitions.
102Â citations
TL;DR: In a 6th-order, intermittent stream system located in north-central Oklahoma, Morphometry, physico-chemical conditions, and community structure of benthic macroinvertebrates were quantitatively related to stream order as discussed by the authors.
Abstract: Morphometry, physico-chemical conditions, and community structure of benthic macroinvertebrates were quantitatively related to stream order in a 6th order, intermittent stream system located in north-central Oklahoma. Number of species and individuals, and species diversity and heterogeneity indices were used as measures of community structure. Average drainage area and average lengths of streams increased, and stream numbers and average gradient decreased exponentially as stream order increased. Physico-chemical fluctuations, mean annual turbidity and water temperature decreased, while mean annual flow, alkalinity, and conductivity increased as stream order increased. Numbers of individuals were maximum in 4th order streams throughout the year. Minimum numbers occurred in the 6th order stream during periods of stream flow, and in 3rd order streams during drought. Annual numbers of species and total community species diversity (H) increased in 3rd, 4th, and 5th order streams and decreased in the 6th order stream. Diversity per individual (H) increased and redundancy (R) decreased as stream order increased. Species diversity was significantly different between and within stream orders at the 75% confidence level, diversity per individual at the 95% level, and redundancy at the 90% level. During autumn, winter, and spring diversity per individual increased and redundancy decreased as stream order increased. Diversity per individual was significantly different at the 95% confidence level during autumn and the 90% level during winter and spring. Significance of redundancy increased from the 25% level during summer and autumn to the 90% level during spring. Annual ranges of species diversity, diversity per individual, and redundancy decreased as stream order increased, indicating more uniform community structure in the higher stream orders. Mean annual heterogeneity (IH) decreased as stream order increased, indicating that similarity of community structure and faunal assemblages increased progressively with stream order. A station located in a 3rd order adventitious stream that flowed directly into the 6th order stream had a community structure and faunal assemblage more similar to stations in higher order streams than to other 3rd order stations. Drought and seepage of oil-field brines upset the stream ordercommunity structure relationship. During drought community structure was similar in all stream orders. Influx of low concentrations of oilfield brines caused diversity per individual to increase and redundancy to decrease, indicating improved stream conditions and more random distribution of individuals into species. More concentrated brines caused diversity per individual to decrease and redundancy to increase, denoting less random distribution and greater repetition of selected species.
100Â citations
TL;DR: The results support the conclusion that the thermal preferendum is independent of previous thermal history and is a reliable character for comparing the extent of thermal adjustment among lizards.
Abstract: Freshly captured Anolis carolinensis regulated body temperatures between 28-36 C in a laboratory photo-thermal gradient, and the mean preferred temperature (MPT) was about 31 C. There was virtually no change in the MPT after 4 months acclimation to 32 C, 20 C or a thermal cycle fluctuating between these two temperatures, with photoperiods of 0, 6, or 14 hours of light daily. Heat resistance, measured as survival time at 42.5 C, was more labile than the thermal preferendum. Maintenance under long day-lengths tended to improve heat resistance at each acclimation temperature, but differences were significant only in animals kept at 20 C. Lizards acclimated to 32 C tended to be more heat resistant than those acclimated to 20 C. The thermal preferendum and heat resistance appear to be somewhat independent with regard to their capacity for modification. These results support the conclusion that the thermal preferendum is independent of previous thermal history and is a reliable character for comparing the extent of thermal adjustment among lizards. INTRODUCTION Interspecific differences in preferred body temperatures (thermal preferenda) and heat resistances among lizards have been regarded as mechanisms for ecologically isolating sympatric species (Bogert, 1949a; Inger, 1959; Licht et al., 1966a), as reflecting phylogenetic relationships (Bogert, 1949a, b; Hirth, 1965; Ushakov, 1964; Licht et al., 1966a), and as indicators of species divergence in physiological adjustments to temperature (Schmidt-Nielsen and Dawson, 1964; UJshakov, 1964; Licht, 1967). Unfortunately, all of these interpretations have been hindered by a lack of information on the "phenotypic stability" of saurian thermal responses. Some seasonal shifts may occur in the body temperatures at which lizards are active in nature (Mayhew, 1963; Warburg, 1965; McGinnis, 1966). However, these observations may reflect the harshness of climatic conditions during certain seasons rather than a change in the inherent thermal preferendum of the species, since lizards may tolerate temperatures outside of their preferred range when climatic conditions are unfavorable for thermoregulation (Licht et al., 1966a; DeWitt, 1967). Species generally continue to regulate at the same levels when provided with wide choices of temperatures in thermal gradient chambers during different seasons even though they show significant variations in the body temperatures at which they are active in nature (DeWitt, 1967; McGinnis, 1966; Licht et al., 1966a). On the 1 This work was supported in part by a grant (GB-2885) from the National Science Foundation to the author.
88Â citations
TL;DR: A field study designed to test the hypothesis that habitat segregation in sympatric populations of Microtus pennsylvanicus and M. mo-ntcrnus is due to competition, found that the voles conform to the principle of competitive exclusion.
Abstract: A field study, designed to test the hypothesis that habitat segregation in sympatric populations of Microtus pennsylvanicus and M. mo-ntcrnus is due to competition, was conducted on the National Bison Range in western Montana between June 1961 and May 1962. Experimental reduction of the numbers of M. pennsylvanicus induced moveiments of M. montanus into the vacated habitat, forming the basis for acceptance of the hypothesis. The nature of the movements plus .reciprocal avoidance behavior of both species of voles during normal circumstances suggest that the voles conform to the principle of competitive exclusion. The. significance of niche overlap is stressed and its adaptive qualities are discussed.
76Â citations
73Â citations
TL;DR: The lacrimal-ectethmoid complex serves as an example of several phylogenetic principles and has greater taxonomic value at the family and subfamily levels than at the ordinal or generic levels, but no taxonomic decisions should be based only on single characters.
Abstract: A single character analysis was undertaken of the lacrimal-ectethmoid bone complex in birds. In order to investigate the structure, variation, function, and possible evolution of the complex, more than 2700 specimens representing all but a few avian families were examined. The lacrimal and ectethmoid bones exhibit much variation within the class. The great structural diversity appears to be the result of "design" and "accidental" (chance-based) evolutionary factors. Among the former is selection for the formfunction complex associated with several important biological roles: (1) a brace for the palatines to prevent breakage during feeding or other activities using the palate, (2) a brace, for the jugal bars to prevent breakage and to contribute to stabilization during kinesis, (3) a retractor-stop mechanism to prevent abnormal retraction, and (4) protection for the eye and for attachment of periorbital connective tissue. The lacrimal-ectethmoid complex serves as an example of several phylogenetic principles. A jugal brace can be brought about independently by the lacrimal or by the ectethmoid, thus illustrating the notion of multiple evolutionary pathways. Also, the evolution of a retractorstop notch in quite unrelated families is a remarkable case of convergence. Examples of parallelism, independent origin, and reversal are also discussed. The complex apparently has greater taxonomic value at the family and subfamily levels than at the ordinal or generic levels. However, no taxonomic decisions should be based only on single characters.
69Â citations
TL;DR: Rates of photosynthesis of axenic hydrophytes under varying nutrient concentrations were determined by rates of 14C bicarbonate uptake and radioassay of organic carbon in gas-phase and photosynthetic responses have been found among phytoplanktonic algae of marl lakes.
Abstract: Studies were undertaken on nutritional factors regulating growth of aquatic macrophytes in calcareous lakes. Sterile cultures of species of Najas, Potamogeton, and Chara were not obtained employing methods that have been utilized in other investigations. Sterile culture techniques and rates of germination were improved by modification of media and conditions for growth. Rates of germination of Najas flexilis were inhibited by low light intensities and were increased markedly by exposure to mild heat treatment in darkness. Light quality, intensity, and duration have significant effects on the germination of Chara. Low light intensities in the visible spectral range provide more favorable conditions for germination. Germination of Najas was similar in both aerated liquid media and in agar of low redox gradients. Various cationic concentrations of the media did not appreciably alter germination of Najas and Chara. Brief treatment with indole-3-acetic acid (1000 mg 1-l) and gibberillic acid (100 mg 1-1) reduced germination markedly. Indirect evidence of chemoorganotrophic growth by Chara in the absence of light was found in the early stages of growth following germination. Rates of photosynthesis of axenic hydrophytes under varying nutrient concentrations were determined by rates of 14C bicarbonate uptake and radioassay of organic carbon in gas-phase. Photosynthetic rates of Najas flexilis were greatly reduced by Ca++ levels above 20 mg 1-F and inhibited by monovalent:divalent cation concentrations below one, in accord with prevailing unfavorable environmental conditions of parent calcareous lakes. Vitamin B-12, but not other water soluble vitamins, stimulated growth of Najas. Similar photosynthetic responses have been found among phytoplanktonic algae of marl lakes.
68Â citations
TL;DR: Jainus gen. n.
Abstract: Jainus gen. n. is proposed and the following new species of Ancyrocephalinae are described from Brazil: Jainus jainus from Chalceus macrolepidotus Cuvier, J. robustus from Creatochanes af/inis (Gunther), Unilatus brittani from Plecostomus sp., Urocleidoides affinis from Creatochanes af/inis, U. carapus and U. gymnotus from Gymnotus carapo Linnaeus, U. microstomus from Hermigrammrus mnicrostomus Durbin, U. stictus from Hyphessobrycon stictus Durbin, and U. virescens from Eigenmannia virescens (Valenciennes). Unilatus unilatus Mizelle and Kritsky, 1967, is included.
TL;DR: A natural history study of the desert woodrat was conducted from August, 1959, to June, 1960, near Jerico, Juab Co., Utah, and revealed an average of 4.9 houses or 1.8 adult woodrats per acre in areas of few junipers to 8.5 houses or 3.1 adult wood Rats in a juniper-sagebrush community typical of the area.
Abstract: A natural history study of the desert woodrat, Neotoma lepida lepida Thomas, was conducted from August, 1959, to June, 1960, near Jerico, Juab Co., Utah. Charted quadrats and a plotless quarter method revealed an average of 4.9 houses or 1.8 adult woodrats per acre in areas of few junipers to 8.5 houses or 3.1 adult woodrats per acre in a juniper-sagebrush community typical of the area. Spherical, conical, or oblong houses, depending on building location, appeared to be randomly dispersed. House details are described. An estimated 37% of the houses were occupied, each usually inhabited by one adult. Oval, circular, or gourd-shaped nests consisted mainly of shredded juniper bark. Food caches contained primarily juniper leaves and berries. Males were more active than females. Strict confinement to one house was not evident. Young woodrats were often found occupying previously unoccupied houses. Some young were parasitized by Cuterebra larvae.
TL;DR: Fifteen previously unreported host-parasite relationships were established and greenbrier seeds, blackberry and insects appeared to be the dominant food items for golden mice in the Great Smoky Mountains National Park.
Abstract: In the Great Smoky Mountains National Park, Ochrotomys nuttalli nuttalli is generally restricted to areas below 2700 ft elevation that are in relatively early stages of succession. The dominant understory vegetation in these areas was either greenbrier or honeysuckle. The dominant tree species were pine, maple, yellow-poplar and sumac. The breeding season extended from approximately mid-March through early October. The population on the main study area fluctuated from a maximum density of 3.6 resident individuals per acre in September, 1964, to a low of 0.24 residents per acre in September, 1965. Two mice were recorded on the study area for 365 and 366 days. Ten individuals were present for eight months or longer, and 19 for periods of five months or more. Average calculated summer home range size for 39 golden mice captured between three and 40 times showed a general increase with an increasing number of captures. Males captured nine or more times had an average home range of 0.64 acre, whereas the female home range averaaed 0.59 acre. The largest home ranges calculated were 1.55 acres for a male and 0.96 acre for a female. The average distance between successive captures for male golden mice was 103 ft in 1964 and 194.5 ft in 1965; that for females was 104 ft in 1964 and 89 ft in 1965. Forty-four arboreal nests were weighed, measured and dissected. Leaves of pine, maple, greenbrier and honeysuckle were used most frequently in nest construction. Seeds were found in 73 % of the nests examined, and varied from less than 1% to 26.8% of the total weight of the nest. Cherry and dogwood seeds were found most frequently. An analysis was made of the food contents of the stomachs and intestinal tracts of 54 golden mice. Greenbrier seeds, blackberry and insects appeared to be the dominant food items. Field observations revealed mice feeding upon cherry and greenbrier seeds, blackberries and the fruit of the sassafras tree. As a result of this study, fifteen previously unreported host-parasite relationships were established. New endoparasites included bacteria, nematodes and a cestode, while the ectoparasites included several genera of mites, fleas and lice.
TL;DR: The Mediterranean gecko, Hemidactylus turcicus, is firmly established in the southern United States and animals were active immediately after nightfall and there was a decrease in numbers of active individuals after midnight.
Abstract: The Mediterranean gecko, Hemidactylus turcicus, is firmly established in the southern United States. Animals were active immediately after nightfall and there was a decrease in numbers of active individuals after midnight. Eighty-two percent of the geckos recaptured one time were within 6 m of the initial capture site. There was no correlation between distance moved by a gecko and time of recapture after marking. Juveniles regenerated their tails faster than males and males faster than females. The relative tail length (tail length/snout-vent length) increased ontogenetically. The sex ratio of adults was almost exactly 1: 1. The reproductive season extended from April to August and females matured in the winter or spring of their second year. About two months were required to produce one clutch of two eggs; each female produced from two to three clutches per season. Eggs were laid in a cleared space and covered with debris. The average incubation period was 40 (37-45) days. Hatchlings had an average snout-vent length of 25.9 (25.0-27.7) mm and resisted starvation and dehydration for 30 to 33 days. In August, the testes were regressed but in December numerous primary spermatocytes were present and spermiogenesis was in progress. In January, one specimen contained a few sperm in the epididymides and the lumina within the testes were well developed. In July, spermatogenic activity was reduced but sperm remained packed in the epididymides. Light period may be the predominant environmental factor controlling reproduction in Hemidactylus turcicus in southern Louisiana.
TL;DR: The following species of Gyrodactylus are originally, comparatively, or redescribed: G. campostomae Wellborn, 1967, from Campostoma anomalum (Rafinesque); G. carpio sp.
Abstract: The following species of Gyrodactylus are originally, comparatively, or redescribed: G. bcaeacanthus Wellborn and Rogers, 1967, from Notropis amoenus (Abbott); G. campostomae Wellborn, 1967, from Campostoma anomalum (Rafinesque); G. carpio sp. n. from Cyprinus carpio Linnaeus; G. eucaliae Ikezaki and Hoffman, 1957, from Eucalia inconstans (Kirtland); G fairporti Van Cleave, 1921, from 29 cotypes (USNM Helm. Coll. No. 37522); G. laruei sp. n. from Campostoma anomalum (Rafinesque); G. nebulosus sp. n. from Ictalurus nebulosus (Rafinesque); and G. stunkardi sp. n. and G. wardi sp. n. (both) from Catostomus occidentalis Ayres.
TL;DR: Wing and tail injuries and defects appeared commonly among members of pallid bat (Antrozous pallidus) colonies in southern Arizona, and it was possible to observe the early stages of injuries and to follow the progress of recovery.
Abstract: Wing and tail injuries and defects appeared commonly among members of pallid bat (Antrozous pallidus) colonies in southern Arizona. These injuries and defects can be grouped into the following categories: (1) membrane holes, ((2) bone abnormalities (nonsymmetrical forearm, curved forearm and fingers, protruding bones, broken fingers, and broken tails), ((3) missing membrane parts, and (4) embedded thorns and cactus spines. Some of these injuries and defects may be due to certain inherent problems occurring in conjunction with battype flight surfaces. The success of bats in spite of such disadvantages is perhaps due to: "extra" wing-load capacity, the ability to fuse broken or dislocated bones, the ability to heal rips and fill in membrane holes, a tolerance of asymmetry, and an ability to limit the continual danger of infection following membrane injury. INTRODUCTION AND METHODS During the summers of 1966 and 1967, as part of a continuing study of the natural history of the pallid bat (Antrozous pallidus), numerous individuals of several colonies located near St. David in southern Arizona were banded and repeatedly recovered. Each individual was weighed and measured, reproductive status was determined, and notes were taken concerning all physical abnormalities. Since many individuals were examined on several occasions, it was sometimes possible to, observe the early stages of injuries and to follow the progress of recovery. In some cases it was possible to estimate the effects that such abnormalities had on the bat. Most obvious was the common occurrence of injuries or other defects of the wings. For example, 28 individuals of a population of 63 (observed on 14 May 1966) had some type of wing defect. The defects ranged from minor and insignificant holes in the wing membrane to more serious conditions such as broken fingers or missing parts. Acknowledgments.-Field assistance for this study was furnished by Gary Bateman, George Lammers, Clay Mitchell, and Sterling Doster. Robert Baker provided special help in both the collection and interpretation of field data, and E. Lendell Cockrum in preparation of the manuscript. Partial financial assistance was provided by funds obtained from a National Science Foundation Institutional Grant administered by The University of Arizona.
TL;DR: The peak standing crop biomass of herbaceous shoots, a measure of net primary shoot production, was determined in three first-year old fields by two methods: sampling the peak community standing crop at one moment and summing the peaks of the individual species over the entire growing season.
Abstract: The peak standing crop biomass of herbaceous shoots, a measure of net primary shoot production, was determined in three first-year old fields by two methods: (1) sampling the peak community standing crop at one moment and (2) summing the peaks of the individual species over the entire growing season. The methods gave similar estimates of peak standing crop in the two old fields where the major producers reached peaks at comparable times. In the third old field, a large discrepancy existed between the two estimates as a result of the diverse times at which the major producers reached peak standing crops. It was valid to use an estimate of net primary shoot production based on the community peak standing crop only when the dominant species had similar phenologies. Whenever this occurred, such an estimate had a smaller statistical error associated with its mean than an estimate derived from the sum of individual species peaks.
TL;DR: Physicochemical conditions and community structure of benthic macroinvertebrates in an oil-field-brine-polluted stream in Oklahoma were studied from October 1963 to September 1964 and information theory methods were used to evaluate community structure.
Abstract: Physicochemical conditions and community structure of benthic macroinvertebrates in an oil-field-brine-polluted stream in Oklahoma were studied from October 1963 to September 1964. Turbidity varied inversely with conductivity and was lowest where brines were more highly concentrated. Seventy-nine species of benthic macroinvertebrates were collected during this study. Numbers of species varied from 31 at stations below the outfall to 55 at the farthest downstream station. Faunal assemblages were dominated by three families of insects: Tendipedidae, Simulidae, and Hydropsychidae. Maximum numbers of individuals occurred at stations in middle reaches where turbidity was lowest. Maximum numbers of species occurred at the extreme downstream station. Information theory methods were used to evaluate community structure of benthic macroinvertebrates. Diversity per m2 (H) was minimal in upper reaches during summer and maximal in middle reaches during winter. Redundancy (R) was minimal in middle reaches during spring and maximal in upper and middle reaches during winter. Diversity per individual (H) was minimal during winter in middle reaches and maximal in the lower reach during summer. INTRODUCTION Benthic organisms have been used by a number of investigators for evaluating stream conditions (Gaufin and Tarzwell, 1952, 1956; Beck, 1954; Hynes, 1958, 1963; Beak, 1964; Wilhm & Dorris, 1966). Because they are relatively immobile, quantitative sampling methods may be employed in obtaining estimates of community structure. Traditionally, stream pollution investigators have attempted to categorize aquatic organisms according to pollutional tolerance (Patrick, 1949; Beck, 1955; Wurtz, 1955; Gaufin, 1958; Beak, 1964). All of these methods suffer from the fact that pollution is varied because effluents produce different effects in different streams. As a result, efforts to classify organisms as to pollutional tolerance have tended to be somewhat subjective. Margalef (1957, 1958) suggested using information theory methods for the formulation of an index that would express diversity. Patten (1962) and Wilhm and Dorris (1966) have utilized this approach. In the present study, indices derived from information theory were applied in the analysis. of benthic macroinvertebrate community structure in a brine-polluted stream. DESCRIPTION OF STUDY AREA Black Bear Creek, a tributary of the Arkansas River, is located in Garfield, Noble and Pawne.e counties in north central Oklahoma ' Contribution 415 from the Zoology Department, Oklahoma State University. 428 This content downloaded from 157.55.39.104 on Sun, 19 Jun 2016 06:42:04 UTC All use subject to http://about.jstor.org/terms 1968 MATHIS AND DORRIS: COMMUN4ITY STRUCTURE 429 (Fig. 1). The main channel is approximately 169 km long and it has an average gradient of 0.9 m/km. Meanders are common, especially in the lower reaches. A method of drainage analysis based on the degree of branching (Horton, 1945; Strahler, 1957) ranks Black Bear Creek as a seventh order stream. Seven stations were selected for study. Station numbers were designated on the basis of distance in kilometers below the stream origin. Stream sediments ranged from cobble to silt in size. Silts and fine sands were found in marginal areas of pools. Coarse sand occurred in mid-pool areas. Riffle areas consisted of coarse sand and pebbles except for Station 125 where cobbles were present. Riffle and pool areas of Station 43 consisted of coarse sand. The riffle area of Station 125 was located on bedrock. Stream discharge and depth varied throughout the year. Riffles were sometimes absent from the two upper stations, but pools persisted even during driest parts of the year. Generally, riffles were abundant in the upper reaches while pools dominated the lower stretches. Maximum depth observed was 1.5 m. Stream discharge increased downstream but was maximum at Station 125. Velocity varied from station to station and was correlated with stream width, the more narrow stations having the greatest velocity. Oil wells in this region produce a mixture of oil and brines. Brines are removed by mechanical separators and either stored in an evaporation pit or allowed to escape into a nearby stream. A major source of brines is the Garber oil field, located in the western third of the basin. This field has numerous oil wells, tank batteries, and separators and many of them are located along Black Bear Creek 24 to 35 km from the origin. Oil installations not included in the Garber field are thinly scattered along the main channel to 65 km downstream. A few / t --Refinery i5 Kilometers Riverkna ~Garber' r ..OlField
TL;DR: Fulvous harvest mice seemed extremely tolerant of one another when confined under laboratory conditions and displayed an activity rhythm seemingly correlated to the onset of dark periods in the absence of well-defined light-dark cycles.
Abstract: Populations of fulvous harvest mice, Reithrodontomys fulvescens, were studied on three areas in Nacogdoches Co., Texas. One area in a pine forest and another in a grass-pine plantation provided comparative population data from 1955-1963. Data secured from the third area, located in a grass-pine ecotone, were useful in determining microhabitat distribution and movements of the differcnt sex and age groups. Fulvous harvest mice occurred predominantly in grassland, pinegrass ecotone, and grass-brush habitat. They were significantly absent from pine-type habitat, possibly because this habitat was occupied by cotton mice, Peromyscus gossypinus, and golden mice, Ochrotomys nuttalli. Fulvous harvest mice were most abundant in winter and to a lesser extent in summer. Peak populations occurred in 1957 in the grass-pine plantation and in 1958 in the adjacent pine forest. The exclusive boundary strip method of analysis of trap range data revealed that harvest mice range over approximately one-half acre. Females had a slightly larger trap range (= home range), .59 acre, than did males, .47 acre; young females averaged greatest linear movements. Neither sex displayed marked territorial behavior. Actual and estimated densities revealed approximately three fulvous harvest mice per acre in the pine-grass ecotone area (probably the optimal area of the three for these mice). There were slightly more males than females on all the areas studied. On the pine-grass ecotone, there were significantly greater numbers of adult males than adult females. Two principal breeding peaks, one in March and a second in July, were detected. Fulvous harvest mice seemed extremely tolerant of one another when confined under laboratory conditions. Mice born in captivity became independent of the female at approximately 3 weeks (the time of weaning). Under controlled laboratory conditions, captives displayed an activity rhythm seemingly correlated to the onset of dark periods. In the absence of well-defined light-dark cycles, activity occurred at times of natural darkness.
TL;DR: The various tetrapod classes show varying degrees of reduction in DNA nuclear content, with the highest levels being retained by the more primitive amphibians and the lowest levels being found in the highly evolved birds.
Abstract: This study attempts to correlate the amounts of DNA per nucleus in the various vertebrate classes with patterns of evolutionary change proposed by Simpson and by Rendel. It is suggested that an increase in the level of DNA/nucleus occurred in the protochordate stock ancestral to the vertebrates and that this led to a major shift from the protochordate to the vertebrate pattern (Rendel's Type 3, Simpson's quantum evolution). In the actinopterygian fishes this was followed by a loss of DNA/nucleus and by the establishment of a number of phyletic lines leading to the higher teleost orders (Rendel's Type 2, Simpson's phyletic evolution). In the Choanichthyes another major increase in the level of nuclear DNA was followed, in one line, by the quantum evolutionary shift to terrestrialism. The various tetrapod classes show varying degrees of reduction in DNA nuclear content, with the highest levels being retained by the more primitive amphibians and the lowest levels being found in the highly evolved birds. The two vertebrate groups with the lowest levels of DNA/nucleus are the higher teleosts and the birds, in which the dominant pattern of evolution today appears to be Rendel's Type 1, Simpson's speciation.
TL;DR: Periodical cicadas emerged in Ohio in 1965 from 15 May to 11 June and Synchrony in emergence may be due to animals reaching a critical threshold temperature.
Abstract: Periodical cicadas emerged in Ohio in 1965 from 15 May to 11 June. Emergence date was related to forest density and slope exposure. Soil temperature at 20-cm depth in seven locations averaged 17.89 C at the time of emergence, regardless of date. Cicadas emerging from burrows had average body temperatures of 18.04 C. Synchrony in emergence may be due to animals reaching a critical threshold temperature.
TL;DR: Live-trapping of Heteromys anomalus melanoleucus in a mosaic environment in the mountains of northern Venezuela in AprilMay, 1960, indicated a preference for primary forest and Heliconia thickets and this species appeared unwary, phlegmatic, and disoriented in comparison with common North American rats and mice.
Abstract: Live-trapping of Heteromys anomalus melanoleucus in a mosaic environment in the mountains of northern Venezuela in AprilMay, 1960, indicated a preference for primary forest and Heliconia thickets. This species was largely segregated from six other species of small terrestrial mammals captured in the same grid of traps. The number of independent young trapped increased greatly in early May, suggesting a surge of mating in the nonrainy season of early March. Signs of breeding in some adults of both sexes were regressing in May, when seasonal rains were approaching peak intensity. The animals were not diurnal and were weakly, if at all, territorial. Home range size was of the order of 600-2500 M2. One female, captured repeatedly, moved 87 m in one 24-hr period. Several rats carried palm nuts in their cheek pouches. Some had fly eggs in their dorsal hair. This species appeared unwary, phlegmatic, and disoriented in comparison with common North American rats and mice.