Browsing by Subject "Costa Rica"

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Biological nitrogen fixation in tropical dry forests of Costa Rica: patterns and controls
(2014-06) Gei, Maria Gabriela
In tropical forests, new nitrogen (N) inputs fuel a large proportion of global net primary productivity. However, global estimates of tropical N fixation are biased towards wet forests and other areas such as tropical dry forests are understudied. In the dry forests of Guanacaste, Costa Rica, N fixing legume trees are highly abundant throughout forest successional stages, thus I hypothesized that in tropical dry forests legume trees are critical regulators of ecosystem level N dynamics. I addressed this question from multiple approaches that included a shade house experiment and field surveys of N fixing legume trees in plantations or in diverse secondary forests using a common set of species: Acosmium panamense, Dalbergia retusa, Enterolobium cyclocarpum, Gliricidia sepium, and Lysiloma divaricatum. Individual legume species had measurable influences on a number of soil properties, but this effect is more pronounced than the influence of legumes as a functional group. I observed species-specific variation in belowground foraging strategies and in the timing and degree of nodulation. In the shade house experiment, species differed in their nodulation effort and in how they regulated N fixation with respect to available resources. These five legume species could be arrayed along a continuum defined by strategies of nutrient conservation and nutrient acquisition, which coincided with degrees of fine-tuning of N fixation. In the field study, I did not find evidence of down-regulation of fixation with soil N. I hypothesized that the adjustment of N fixation to soil nutrients occurs indirectly and is mediated by water availability and its effects on nutrient pulses. My stand-level estimates N fixation by legumes showed that legumes are responsible for the largest contribution of new N inputs to this ecosystem relative to other inputs such as free-living fixation or wet deposition, but which are modest relative to N recycling through leaf litter and fine root decomposition. Different legume strategies could represent different ways of dealing with the transient and seasonal water availability of this ecosystem. Collectively, my results suggest that the conceptual models of how N fixation works in tropical wet forests may not necessarily be the same in seasonally dry forests.
The caddisfly genus Nectopsyche: new gemma group species from Costa Rica and the Neotropics (Trichoptera:Leptoceridae)
(University of Chicago Press, 1995) Holzenthal, Ralph W.
Generic-level diagnoses are provided for adult males, females, and larvae of the longhorned caddisfly genus Nectopsyche Miiller (Trichoptera:Leptoceridae). In addition, seven new Costa Rican species in the gemma species group are described and illustrated: N. exophthalma n. sp., N. monticola n. sp., N. onyx n. sp., N. ortizi n. sp., (also known from Argentina, Brazil, Guyana, Mexico, Panama, Peru, Surinam, and Venezuela), N. tapanti n. sp., N. tuanis n. sp., and N. utleyorum n. sp. The new species are compared with two previously described gemma group species also known from Costa Rica, N. argentata Flint and N. gemmoides Flint, and these, too, are diagnosed and illustrated.
The caddisfly genus Protoptila in Costa Rica (Trichoptera: Glossosomatidae)
(Magnolia Press, 2006) Holzenthal, Ralph W.; Blahnik, Roger J.
Nineteen species of Protoptila known from Costa Rica are revised to include 11 previously described species (P. bicornuta Flint 1963, P. boruca Flint 1974, P. burica Flint 1974, P. cana Flint 1974, P. ixtala Mosely 1937, P. laterospina Flint 1967, P. orotina orotina Flint 1974, P. spirifera Flint 1974, P. talamanca Flint 1974, P. tica Bueno-Soria 1984, and P. tojana Mosely 1954) and 8 new species (P. altura, P. bribri, P. chitaria, P. cristula, P. kjeri, P. jolandae, P. strepsicera, and P. trichoglossa). Illustrations, diagnoses, descriptions, and distribution records are provided for all species.
Costa Rica - Sustainable horticulture crop production
(2010-11-28) Palmer, Rachel
Cumulative Effects of Coastal Watershed Land Use on Chironomidae (Insecta: Diptera) Communities of Neotropical Estuaries in Costa Rica
(2017-07) Kranzfelder, Petra
Chironomidae assemblages are likely to provide a useful measure of biotic integrity in Neotropical estuaries of Costa Rica, which lack an intensive estuarine bioassessment tool to support environmental monitoring. However, little is known about chironomid communities in these estuaries and the cumulative effects of watershed land use on chironomid communities have not been studied. The purpose of this dissertation was to (1) quantify land cover change of six watersheds on the Caribbean coast of Costa Rica between 2001 and 2014, (2) describe all steps of the Chironomidae surface-floating pupal exuviae method in detail, including sample collection, laboratory processing, slide mounting, and genus identification, (3) investigate Chironomidae species diversity of nine estuaries across a land use gradient on the Caribbean coast of Costa Rica, (4) compare the relative effectiveness of five different DNA extraction protocols and direct PCR in isolation of DNA from chironomid pupal exuviae, and (5) assess the efficiency of using standard DNA barcoding for species identification of chironomid pupal exuviae. I found that watershed-scale land use analyses showed agricultural expansion and deforestation in watersheds on the northeastern coast and secondary forest regrowth on the southeastern coast of Costa Rica. I identified 228 morphospecies and 70 genera from 17,071 Chironomidae surface-floating pupal exuviae collected from nine Neotropical estuaries and that a Chironomidae Index of Biotic Integrity successfully discriminated estuaries with differing degrees of stress across a land use gradient. I extracted genomic DNA from 61.2% of 570 sampled pupal exuviae. The NucleoSpin® Tissue XS Kit, DNeasy® Blood and Tissue kit, and QuickExtract™ DNA Extraction Solution provided the best results in isolating DNA from single pupal exuviae. A total of 36.3% of 190 sampled pupal exuviae resulted in high-quality sequences for Costa Rica, but none matched known species. This knowledge is important if these aquatic communities are to be used more effectively in future biological monitoring, conservation, and integrated water resource management of Neotropical estuaries.
The genus Ochrotrichia Mosely (Trichoptera: Hydroptilidae) in Costa Rica, with the description of four new species
(Magnolia Press, 2008) Bueno-Soria, Joaquin; Holzenthal, Ralph W.
Four new species of the genus Ochrotrichia Mosely, are described from Costa Rica and the male genitalia figured (Ochrotrichia avicula new species, Ochrotrichia conformalis new species, Ochrotrichia jolandae new species, and Ochrotrichia quasi new species). Twenty-five species are recorded from Costa Rica, 8 for the first time [O. aldama (Mosely), O. arranca (Mosely), O. assita Bueno-Soria & Holzenthal, O. caimita Flint, O. glabra Bueno-Soria & Santiago-Fragoso, O. hondurenia Bueno-Soria & Santiago-Fragoso, O. panamensis Flint, and O. tagala Flint] and new distributional records are listed. Ochrotrichia arranca (Mosely) is refigured and compared with O. conformalis, new species and O. quasi, new species.
Honey production by Africanized and European honey bees in Costa Rica
(Springer, 1989) Spivak, M.; Batra, S.; Segreda, F.; Castro, A.L.; Ramirez, W.
Seventeen colonies of bees were used in a test of honey production in a coffee plantation in Costa Rica. The identities of the colonies were not known at the beginning of the experiment. Behavioral identifications were made in the field as to whether a colony was ’strongly Africanized’, ’strongly European’ or ’intermediate’. The distance spanned by 10 linear worker cells was also measured in the field. Morphometric analyses, conducted independenUy, identified colonies as probably Africanized or probably European. Although the ’intermediate’ category tended to produce more honey, there was no significant difference in honey production between bee types, whether sorted by behavior or morphometrics. There was no significant correlation between initial colony weight or brood area and total amount of honey produced. Appropriate uses of behavioral and morphometric identifications are discussed.
The Larva and Pupa of Cochliopsyche vazquezae (Trichoptera:Helicopsychidae)
(University of Chicago Press, 1988) Monson, Margot P.; Holzenthal, Ralph W.; Ahlstrand, Gilbert G.
The larva and pupa of Cochliopsyche vazquezae Flint are described, representing the first complete description of these stages for the genus. The larva is characterized by the possession of a prominent patch of setae on the anterolateral margin of the head capsule and by a marked concavity in the postgenal region, giving a "hollowed out" appearance to the posterolateral aspect of the head. Pupae bear a similar group of setae below and mesad of the eye. Notes on the biology and habitat of C. vazquezae in Costa Rica are given.
New species of Smicridea (Rhyacophylax) (Trichopera: Hydropsychidae) from Costa Rica
(American Entomological Society, 1995) Holzentahl, Ralph W.; Blahnik, Roger J.
Three new species in lhe caddjsfly genus Smicridea, subgenus Rhyacophylax, are described from Costa Rica and 25 additional species in the two recognized subgenera are recorded from the country. Illustrations of the male and female genitalia and wing coloration are provided for each of the new species along with a map of their distributions. Two of the new species, S. singri and S. nemorosa, are in the signota species group. and the third, S. rapanti, is a member of the peruana species group.
Population genetic structure, pollen dispersal, and local adaptation in Quercus oleoides forests of Costa Rica
(2010-08) Deacon, Nicholas
Recent and ongoing anthropogenic land use has altered natural landscapes and resulted in isolated patches of native vegetation across the globe. This process of habitat fragmentation reduces continuous habitat into small remnants in a matrix of altered terrain. The impetus for this research was to contribute to the growing body of work on the effects of habitat fragmentation while simultaneously gaining a better understanding of the specific role that recent fragmentation played in the evolution and demography of the most ubiquitous species in one particular region. My goal was to understand the evolutionary history of Quercus oleoides in Costa Rica in order to more effectively conserve and possibly restore the region’s seasonally dry forest in the future. How has the conversion of the seasonally dry forest of Costa Rica to an agricultural mosaic affected Quercus oleoides (live oak), the dominant tree species of remnant forest fragments? Although studies addressing the genetic consequences of habitat fragmentation are becoming more common, assessments of genetic structure and population viability that inform management decisions for conservation and restoration are rare. This study combined analyses of genetic diversity, pollen dispersal, and the growth and survival of various seedling families to provide an integrated evaluation of the response of a critical dry forest species to fragmentation and will help guide management and restoration efforts in the Aréa de Conservación Guanacaste (ACG). v The Q. oleoides forests of Guanacaste province, Costa Rica are something of a biological enigma: they are geographically disjunct and genetically distinct from conspecifics and similar species, and geographically quite restricted within Costa Rica while spanning a broad range of environments and associations within that range. Quercus oleoides is ectomycorrhizal in a habitat dominated by endomycorrhizal associations, possesses an atypical developmental process with regard to germination and emergence system, produces a fruit type that is extremely rare in the tropics, is wind pollinated in a habitat dominated by insectpollinated species, is evergreen in a habitat where most species are deciduous or semi-deciduous, and its reproductive phenology is largely mismatched to the seasonally dry environment of Guanacaste, producing large crops of dessicationsusceptible acorns at the beginning of a dry season more severe than what the species encounters anywhere else in its range. Despite this seeming mismatch between traits and environment, Q. oleoides is by far the most common large tree wherever it occurs. As such it is an extremely important structural species in Guanacaste dry forest. Its seeds are consumed by a wide range of mammalian and avian seed predators and its evergreen habit undoubtedly has a large effect on the abiotic environment experienced by many dry forest organisms. The subsequent chapters describe three previously unanswered questions about the past, present, and future status of Q. oleoides in the ACG. In Chapter 1, I characterized the standing genetic diversity of 13 Q. oleoides populations vi and the geographic structuring of that diversity. The pattern of that diversity was compared to geographic distance, flowering time similarity, and environmental similarity among populations. The structuring of genetic diversity was also compared between two age cohorts representing pre-fragmentation individuals and post-fragmentation individuals. I found that Q. oleoides in Costa Rica contained a high level of genetic diversity as well as genetic variation that is geographically structured across the landscape. The degree to which this structuring is due to fragmentation, however, is small in comparison to the genetic structure that has existed prior to fragmentation. This is somewhat counterintuitive due to the expectations provided from population genetic theory that can be applied to fragmented landscapes. If habitat fragments are isolated from one another such that gene flow no longer occurs among them, inbreeding may reduce offspring fitness and limit the viability of populations in those fragments. Isolated habitat fragments then become genetically differentiated over time due to the random process of genetic drift. Genetic diversity may also be affected because the amount of genetic variability in a population decreases due to the loss of rare alleles when the individuals carrying them are removed. This is termed a genetic bottleneck because the genetic variability of future generations is contained in the few surviving individuals. Small populations are vulnerable to stochastic environmental and demographic occurrences because adaptation by an organism to a changing environment depends on the genetic variability present in the population. The loss of genetic diversity reduces future evolutionary options and can lead to extinction. Population genetic variation consists of the sum of all genetic variation among individuals within the population. It can be measured by parameters including allelic richness (A) and expected heterozygosity (He). Allelic richness is the average number of alleles per locus and observed heterozygosity is compared to expected heterozygosity under Hardy-Weinberg equilibrium conditions. Wright’s F-statistics are means of describing how genetic diversity is partitioned in a population. High values for FST indicate that subpopulations have very different gene frequencies than the total population. A loss in heterozygosity can occur with inbreeding due to the higher chance that offspring of a mating event between two individuals with the same common ancestor may share the same alleles. One method for quantifying genetic variation within species is to assay highly variable regions of repeated DNA units called microsatellites. Individuals of a population were characterized by the differences in length of 11 of these non-coding genetic units. Although I observed no significant correlations between genetic distance and geographic distance, flowering time similarity, or environmental similarity in Chapter 1; I analyzed pollen dispersal more rigorously in Chapter 2 in order to better calculate contemporary pollen dispersal distance estimates. It is not unusual for studies of plant populations in fragmented landscapes to report few of the negative consequences predicted by theory, and that is because pollen may actually disperse father in fragmented landscapes. My results from two separate molecular analyses of pollen dispersal distance using 8 of the microsatellite markers from Chapter 1, however, indicated that the average pollen dispersal that resulted in viable offspring predominately occurred over very short distances. Both the paternity exclusion and two-generation methods yielded similarly short dispersal distance estimates. Evidence from the physical trapping of pollen in one location indicated that pollen was capable of moving much farther, however, so the importance of long distance pollen dispersal may rely more on phenology. I observed staminate and pistillate flowering times in 10 sites over two years, but the lack of strong seasonality in flowering obscured any obvious patterns. The geographic structuring of genetic diversity and the short average pollen dispersal distance provide a sound foundation for testing for local adaptation in Q. oleoides populations. In Chapter 3, I compared the growth and survival of upland and lowland maternal families in their native and foreign environments. The native environment of the populations of families differs most notably in their elevations and the lack of precipitation during the 4-5 month dry season in the lowlands. Seedlings planted in the lowland garden from both populations experienced a much higher level of mortality than seedlings planted in the upland garden, but using the aster models approach for comparing the likelihood of various models of combined growth and survival data, we did not identify evidence for local adaptation. Overall, these experiments indicate that contemporary Q. oleoides in Costa Rica have a rich and complicated population genetic history that despite obvious and extensive habitat fragmentation has not severely affected genetic variation or demographic processes. The long term outlook for the recovery of the tropical dry forests in general and the Q. oleoides stands, in particular, is good. Little direct action by managers is required and any active planting efforts do not seem to be encumbered by site-specific seed requirements. I do recommend local seed sources, however, out of an abundance of caution. These results not only add to the field fragmentation studies by examining a common, tropical tree over multiple habitats; this work also provides applicable information to an actively managed region that is in a transitory successional state.
The snail-case caddisfly subgenus Helicopsyche (Feropsyche) in Costa Rica, with the description of 3 new species (Trichoptera: Helicopsychidae)
(Magnolia Press, 2010) Johanson, Kjell A.; Holzenthal, Ralph W.
Thirteen species of Helicopsyche, subgenus Feropsyche (Trichoptera: Helicopsychidae) are recorded from Costa Rica, including 3 new species: H. alajuela, n. sp., H. dorsocurvata, n. sp., and H. golfitoensis, n. sp., as well as 10 previously described species: H. borealis (Hagen), H. chiriquensis Johanson & Malm, H. dampfi Ross, H. incisa Ross, H. lewalleniDenning & Blickle, H. mexicana Banks, H. rentzi Denning & Blickle, H. selanderi Ross, H. truncata Ross, and H. vergelana Ross. The male genitalia of the new species are illustrated and distribution maps are provided for all species.
Two new genera of Hydroptilidae from the neotropics (Trichoptera: Hydroptilidae: Stactobiini).
(New York Entomological Society, 2002) Harris, Steven C.; Flint, Oliver S. JR; Holzenthal, Ralph W.
Two new monotypic genera of stactobine microcaddisflies (Trichoptera: Hydroptilidae), Orinocotrichia, and Tizatetrichia, are described and illustrated from Venezuela and Costa Rica, respectively. Keys are provided for males and females of the New World generacomprising the tribe Stactobiini.

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