Showing papers by "University of Costa Rica published in 1982"

Aggressive and Courtship Displays of the Male Anna's Hummingbird

Abstract: -The aggressive and courtship displays and vocalizations of the male Anna’s Hummingbird (Culypte anna) are described in detail, and various types of evidence and observations are used to reconstruct the typical courtship sequence. Initial contact is made by the female flying to the male’s territory and attempting to feed; she may have previously visited several other territories in order to evaluate territory quality. The well-known dive display is an aggressive maneuver by the male, although it may play a role very early in the courtship sequence. Following a lengthy chase towards the female’s nesting area, she alights low in dense vegetation. The male then gives the displays most critical for courtship: a back-and-forth “shuttle” display and high-intensity song. These hitherto undescribed displays occur immediately preceding copulation, and are probably the most important isolating mechanisms for the species. Many of the elements of courtship in C. an~la are widespread in hummingbirds. Practice and probably learning play a major role in the maturation of song and dive displays in the individual. The courtship sequence in this hummingbird probably represents the resultant of various selective pressures, some acting mainly on males and others on females. Hummingbirds are becoming among the beststudied of North American birds, particularly with respect to energetic aspects of nesting (Horvath 1967, Calder 197 1, 1974, Calder and Booser 1973, Smith et al. 1974) territoriality and foraging (Stiles 197 la, Ewald and Carpenter 1978, Kodric-Brown and Brown 1979, Pyke 1978, Gass 1979) and relationships with the flowers they visit and pollinate (Stiles 1973, Carpenter 1978, Waser 1978, KodricBrown and Brown 1979, Price and Waser 1979). Recent field studies in California have disclosed a striking amount of hybridization among several (newly?) sympatric species (Lynch and Ames 1970, Wells et al. 1978, Wells and Baptista 1979). Study of hybrids and parental types in nature offers a unique opportunity to document the ecological and behavioral effects of such hybridization. Analyses of these phenomena, however, have been hindered by the lack of reliable descriptions of courtship and aggressive displays of the species concerned. The conspicuous dive displays have been described with varying degrees of completeness and accuracy by Bent (1940) Banks and Johnson (196 l), Wells et al, (1978) and Wells and Baptista (1979), among others, but except for the perceptive discussions of Pitelka (1942, 19 5 1 a, b) their role in courtship has been misunderstood. Moreover, a whole family of close-range displays in these hummingbirds, far more crucial in courtship per se, has been overlooked. Finally, I know of no good descriptions of display sequences nor, indeed, of copulation itself in these birds. Behavioral isolating mechanisms in North American hummingbirds cannot be properly appraised without a clear understanding of what actually constitutes their courtship. Through several years of close study of the ecology and behavior of the Anna’s Hummingbird (Calypte annu) and other California species (Stiles 1973) I was able to observe courtship and aggressive displays ofthese birds in detail. My purpose here is to describe and interpret the vocalizations and displays of the Anna’s Hummingbird, to serve as a basis for comparisons with other species.

Sociocultural Factors in the Control and Prevention of Parasitic Diseases

Abstract: Control and prevention of parasitic disease depends on an adequate knowledge of interactions among factors such as human behavior, the environment, and the life cycles of parasites. Sociocultural factors in large part determine transmission and persistence of parasites. The main determinants are poverty, low educational level, deficiencies in home technologies, high demographic density, and ruralism. Selected interventions designed to improve any of these situations may fail if they are applied in an isolated manner. The holistic implementation of interventions has proved successful in the control and prevention of parasitic infections in several parts of the word. The implementation of several kinds of interventions simultaneously, that is, a holistic approach, combined with an awareness of a society's infrastructure, can produce favorable results. For such an awareness--when it provokes action--can improve the overall quality of life.

Embryological stages of the marine turtle Lepidochelys olivacea (Eschscholtz)

Abstract: Embryos of the Pacific Ridley Turtle, Lepidochelys olivacea , obtained from eggs from the Pacific Coast of Costa Rica and Panama, developing on a beach and others incubated in the laboratory respectlvely, were exarnined and evaluated in terms of development by means of an lndex of Morphological Development (IMD); selected morphological characters and measurements were used to diagnose 31 different developmental stages from gastrula to neonate.

Migration and genetic infrastructure of the Central American Guaymi and their affinities with other tribal groups.

Abstract: Articulo cientifico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1982. Este documento es privado debido a limitaciones de derechos de autor.

Aspectos biomédicos de cuatro casos de mordedura de serpiente por Lachesis muta (Ophidia: Viperidae) en Costa Rica

Abstract: Three out of four cases of snake bite by Lachesis muta stenophrys (Bushmaster) in Costa Rica were fatal and one recovered after a long period of hospitalization Initial symptoms were similar to those of bothropic envenomation: intense pain, nausea, vomiting, sweating, and excitability, but differing in the magnitude of a tremendous edema and in the absence of intensive bleeding and phlyctenae We found important alterations in arterial blood pressure and in the activity and concentration of coagulation factors All patients showed infections, and necrosis was found in at least three of them

Nitrogen cycling in coffee plantations

Abstract: Nitrogen inputs to the coffee ecosystem are dominated by additions of fertilizer-N (100–300kg N ha-1 yr-1). Small nitrogen inputs from rains and variable from inputs fixation by the leguminous shade trees can amount to 1–40 kg N ha-1 yr-1. Organic matter mineralization can be an important nitrogen source also.

The changes in cyanide content of cassava (Manihot esculenta crantz) tissues during plant development

Abstract: The cyanide concentrations in the leaves, meristems, root cortex and root parenchymal tissues of cassava (cv. Valencia) were investigated at 2-month intervals up to a plant age of 17 months. Six plants were analysed at each interval and sampling methods investigated to ensure that the cyanide estimations (by enzymic assay) were representative for each plant. Root yield per plant increased to 10 months and then remained almost constant to 17 months. Leaf weight per plant reached a maximum at 6 months (380 g per plant), decreased to 12 months and then slowly increased. Cyanide concentrations in the root parenchymal tissue and root cortex were not significantly different between 6 and 14 months; both tissues displayed peak concentrations at 6 and 14 months. Cyanide concentration maxima in the leaves appeared to precede those shown by the roots. Meristem concentrations showed similar trends to those shown by the leaves. The precise plant age at harvest had little effect on the potential toxicity of the roots. A modification to the earlier published procedure for leaf tissue is described. The cyanide concentration in old (green) leaves was < 50% of that in young leaves of the same plant. Intra-leaf and inter-leaf cyanide concentration variations are described, and the importance to low-cyanide cassava screening programmes indicated.

Comparison of dispersal of crab larvae in delaware bay, usa, and the gulf of nicoya, central america

Abstract: We present a comparison of factors affecting dispersal and recruitment of larvae of estuarine species in tropical and temperate regions. Species of the blue crab Callinectes spawn in the lower reaches of estuaries in both regions and their larvae are exposed to risk of transport out of the estuary and consequently to habitats that are unsuitable for adult existence. We review available data demonstrating that larvae of Callinectes sapidus are indeed carried out of the major estuaries of the Middle-Atlantic Bight, undergo development on the shelf, and are eventually transported back into the estuary. We present data suggesting that larvae of Callinectes arcuatus may also be exported from the estuaries of the eastern tropical Pacific, and we discuss turbulent and advective mechanisms of recruitment in the light of known patterns of circulation in both areas.

Polinización en Bactris gasipaes H.B.K. (Palmae): Nota adicional

Abstract: The purpose of this short paper is to provide some supplementary information for a previously published article on the pollination of Pejibaye. In the former article it was established that three methods of pollination –insect, wind and gravity – occur in this palm; and that the curculionid Derelomus palmarum Champ. was the main pollinator in populations from Costa Rica. It is here reported that in the Pejibaye populations from El Chapare in Bolivia and other Amazon Basin areas, such as Manaus in Brasil. Derelomus palmarum is substituted mainly by one species of another very closely related genus -Phyllotrox- which is not yet described in the literature. Also, another undescribed species of Phyllotrox was found to be the main pollinator of another unidentified species of Bactris from Bolivia. In both cases, a second undescribed species of Phyllotrox accompanied the main pollinator. That secondary pollinator was also different for both species of Bactris. It is postulated that if Bactris is a monophyletic genus most probably the pollinators of its numerous species must be found among members of the tribe Derelomini, mainly from these two genera, Derelomus and Phyllotrox. A short discussion is also given on the possible relationship between these two populations of Pejibaye (from the Amazon Basin and northwestern side of the Andean Mountains) based on these closely related insect pollinators. Mention is also made of the possible predominant role of the curculionids as pollinators of the palms.

Cytogenetics of the chinese giant salamander, Andrias davidianus (Blanchard): the evolutionary significance of cryptobranchoid karyotypes

Abstract: Cytogenetic aspects of the cryptobranchid salamander Andrias davidianus of western China have been studied, including chromosome number and morphology, C-band patterns, meiosis, and the chromosomal localization of ribosomal 5S RNA genes. Our data regarding chromosome number (2n=60) and general chromosome morphology largely confirm the results of Morescalchi et al. (1977). The karyotype consists of 16 pairs of “macrochromosomes” that decrease gradually in relative length to 14 pairs of “microchromosomes”. Telocentric chromosomes are a conspicuous feature of the karyotype, representing more than half the genome. Differential staining reveals that all of the chromosomes, except four pairs of microchromosomes, have C-band heterochromatin in their centromeric regions, the amount varying irrespective of chromosome size. Faint bands of interstitial and telomeric C-band heterochromatin are found in mitotic chromosomes but are not seen in meiotic preparations. In C-banded mitotic preparations from a female, one of the smallest macrochromosome pairs is heteromorphic in respect to C-band heterochromatin and centromere position. In situ hybridization of an iodinated 5S RNA probe to meiotic chromosome preparations reveals that this repeated gene is clustered near the telomeric region of chromosome 7, a medium size telocentric, a location corresponding to a band of heterochromatin. Studies of spermatocytes indicate that the process of meiosis in A. davidianus closely resembles that of more advanced salamanders, and that the microchromosomes are meiotically stable. The significance of microchromosomes and chromosome morphology in the reorganization of salamander genomes during evolution is discussed on the basis of cytogenetic data available for A. davidianus and various other primitive and advanced salamanders.

An evaluation of enzymic and autolytic assays for cyanide in cassava (Manihot esculenta, crantz)

Abstract: The total cyanide contents of cassava parenchymal tissue (peeled roots), cassava cortex (peel) and cassava leaves were evaluated by autolytic and enzymic assays Autolysis of parenchymal tissue was studied under different conditions of pH, time and temperature and addition of exogenous enzyme and antibiotic Optimal conditions were determined to be 24 h at 37°C in acetate buffer (01M; pH 55) with 01 mg ml−1 chloramphenicol Total cyanide contents similar (about 90%) to those obtained by enzymic assay could be achieved only by the use of small sample sizes: < 1 g of parenchymal tissue, < 03 g of cortex and < 01 g of leaf tissue This caused sampling problems because of the presence of cyanide gradients in cassava tissues, which could only be resolved by tissue homogenisation prior to analysis A study using the enzymic assay of cyanide stability in such homogenates, at different pH values and temperatures, has indicated that subsampling must be done within 15 min so as to prevent appreciable losses in the measured cyanide contents The rate of loss of total cyanide was found to depend not only on the proportion of total cyanide which is non-glucosidic (free), but also on the proportion of the non-glucosidic cyanide present as cyanohydrins The implications with regard to residual cyanide contents on cassava processing and the advantages of the enzymic assay over autolytic methods are discussed

The anatomy of the pistillate inflorescence and flower of Casuarina verticillata Lamarck (Casuarinaceae)

Abstract: The pistillate inflorescence of Casuarina verticillata is described as consisting of a primary axis bearing whorls of bracts with a cymule in the axil of each bract of the more central whorls. Each cymule consists of an atepallate, two-carpellate, syncarpous floret and two, lateral, oncelobed bracteoles. A "peripheral intercalary" meristem, in which divisions are primarily periclinal, forms a meshwork beneath the bracts from early development and moves the connate bracts centrifugally around the cymules and extends and binds the bracts, and to some extent the bracteoles, of the fertile part of the inflorescence together. Each bract receives a single trace; each cymule receives two traces. Each bundle extension of a cymule trace supplies: 1) a branch which joins its counterpart to become the anterior common carpellary bundle; 2) a second branch which joins its counterpart to become the posterior common carpellary bundle; and 3) a central branch which supplies a lateral bracteole. Within each floret, each common carpellary bundle provides a dorsal carpellary bundle, two ventral carpellary bundles (fertile anterior carpel) or one common ventral bundle (sterile posterior carpel). The ventral bundlesupplies join and form a single placental bundle which lies in the gynoecial septum, and which, in turn, supplies the two ovules in the anterior carpel. Whether the inflorescence is a simple racemose or a condensed cymose type cannot be determined from this species alone. The function of the scierenchymatous, enclosing bracteoles and connate bracts is discussed.

Environmental conditions and structure of the West African and Eastern Tropical Atlantic squall lines. Umgebungsverhältnisse und Struktur der Böenlinien in West-Afrika und im östlichen tropischen Atlantik

Abstract: The environmental conditions in advance of three West African disturbance lines and three Eastern Atlantic squall lines are examined as is the modification of the environment during the passage of such storms over a site. A comparison with other tropical squall lines observed over Venezuela is made. A model of the relative airflow within a West African disturbance line is presented and some aspects of storm movement are considered. The hydraulic jump analogy and a density current model are applied to the convective systems and the results obtained are compared with observations. The hydraulic jump analogy gives reasonable predictions for the storms' speeds and the density current model results show that for the West African disturbance lines, as well as the Venezuelan storms, a close relationship exists between the storm speed and the speed of the density current. As this relationship is not observed in the Eastern Atlantic squall lines, it appears that the density current model is not applicable to convective systems occurring over the ocean.

G6PD-Puerto Limón: a new deficient variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia

Abstract: A new glucose-6-phosphate dehydrogenase (G6PD) variant with total deficiency associated with congenital nonspherocytic hemolytic anemia was found in a Costa Rican family. The study of the partially purified enzyme revealed thermal instability, increased G6P affinity, abnormal pH optimum, increased utilization of analogues, and a chromatographic behavior that differs from all the variants previously described. Thus, this new variant was designated G6PD Puerto Limon.

La estimulación temprana: apuntes sobre sus fundamentos teóricos, bases empíricas y raíces socio-históricas. Elementos para una discusión

Abstract: ...Una gran variedad de grupos de interes estan satisfechos: los educadores por el prestigio y los fondos que significa, los reformadores sociales porque creen en la educacion, los legisladores porque pueden aprobar leyes de cariz positivo... Bajo esta perspectiva, el movimiento a favor de la educacion temprana aparece cada vez mas como una gigantesca evasion, un complejo ritual que enfoca al futuro como medio para evitar la accion significativa con respecto a los apremiantes problemas sociales actuales. Largetson. Social reform and early childhood education: Some historical perspectives. Urban Education, 1970, p.84

Moscas sarcofágidas de Costa Rica (Diptera; Cyclorrhapha)

Abstract: A brief review of the sarcophagid flies of Costa Rica revealed the presence of 34 species in 21 genera. Some of these species are associated with flowers, rotting fruits and human cadavers.

La Doctrina Monroe, el Destino Manifiesto y la expansión de Estados Unidos sobre América Latina. El caso de México

Abstract: Durante la epoca del dominio europeo, America Latina fue sometida a una estrujan te relacion de dependencia economica que se ha prolongado hasta nuestros dias, y bien puede considerarse una herencia colonial. Espana y Portugal, en los siglos de la conquista y colonizacion de America, se caracterizaron por una economia debil y dependiente. "La Europa Dominante" como la llamo Mousnier, (principalmente Inglaterra y Flandes) dominaron la economia y el comercio europeo en los siglos XVI y XVII.