• Harmothoe imbricata: species complex or complex species?

      Gastaldi, Angela; Lopez, J. Andres; Hardy, Sarah; Kelley, Amanda; Sikes, Derek (2019-05)
      Accurate estimates of species diversity are constrained by cryptic species complexes, in which multiple closely related species are grouped under a single species name due to the absence of clear morphological differences. Cryptic diversity is known to be prevalent in polychaete worms, a mostly marine group commonly known as bristle worms. A recent survey of polychaete diversity discovered that the widespread scale-worm Harmothoe imbricata comprises multiple distinct mitochondrial lineages based on analysis of the Cytochrome c oxidase I (COI) gene, which is often referred to as the 'barcoding' gene. Analyses based solely on DNA sequences from COI may overestimate the number of lineages comprising a cryptic species complex, so it has been recommended that cryptic species investigations incorporate nuclear gene sequences. The goal of this study was to determine whether the incorporation of DNA sequences from the nuclear genome corroborates the designation of H. imbricata as a cryptic species complex. I sequenced segments of COI and five nuclear genes: ITS1, ITS2, H3, and portions of the 18S and 28S genes of H. imbricata and analyzed them using distance measures, maximum likelihood, and Bayesian inference. I compared phylogenetic trees produced from mitochondrial and nuclear DNA sequences, as well as from a combined mitochondrial/nuclear dataset. Harmothoe imbricata was found to include five mitochondrial lineages, whereas the nuclear sequences only supported four well-defined lineages. These results corroborate previous reports showing COIbased cryptic species investigations find more lineages than nuclear DNA based investigations. These results provide additional lines of evidence that H. imbricata is a cryptic species complex. These divergent lineages likely arose after being separated during the last glacial maximum but they are now found in sympatry. A thorough morphological study of H. imbricata populations may reveal phenotypic differences correlated with the genetic lineages identified here.
    • Morphological and phenological responses of butterflies to seasonal temperature increase in Alaska

      Daly, Kathryn Margaret; Breed, Greg A.; Sikes, Derek S.; Mann, Daniel H. (2018-12)
      Climate is changing rapidly at high latitudes, and the responses of insects provide early indications of the impacts these changes have on biota. Butterflies (Lepidoptera: Papilionoidea) are among the best-known Subarctic and Arctic insects, and research in Greenland has revealed significant declines in butterfly body sizes along with advances in the timing of their first flights in spring. These changes are ecologically significant because smaller body sizes can lead to reduced fecundity in butterflies, and earlier adult emergence can have detrimental effects across trophic levels because Lepidoptera are an important food resource for birds and mammals. The primary goal of this thesis is to expand the geographical scope of previous studies of butterfly responses to high-latitude warming by testing whether Alaskan butterflies have exhibited morphological (Chapter 1) and/or phenological (Chapter 2) changes in response to rising temperatures. The morphological parameter studied here is forewing length, and the phenological parameter the timing of the first-observed flight of the year. Results show that the wings of two out of three butterfly species studied from Alaska's North Slope and Seward Peninsula decreased as seasonal (spring and summer) temperatures rose between 1971 and 1995. For every 1° C increase in average seasonal temperatures, wingspans decreased by up to 1.4 millimeters in Alaska. This compares to decreases of up to 0.65 millimeters observed in Greenland. One Alaskan species, Colias hecla Lefebvre 1836, did not show significant change in its wing lengths, although it did exhibit significant decreases in Greenland. Differences in life-history traits among species appear to result in divergent responses in Alaskan butterflies, with Boloria freija (Thunberg, 1791), which overwinters as late-instar larvae, showing the greatest decrease in wing length compared to Boloria chariclea (Edwards, 1883) which overwinters as early-instar larvae. From the start of the collection record in 1966 onward, collection and observational records from Interior Alaska reveal an average phenological advancement of 1 to 5 days/decade in 13 spring-emerging butterfly species. The morphological and phenological changes found in some species of Alaskan butterflies correlate with recent climate change, though the effects differed among species. The eco-physiological responses to climate change observed here for butterflies are likely to be shared by other insect species living at high latitudes.
    • Studies assessing insulin signaling dependent neuronal morphology and novel animal sorting methods in a C. elegans model

      Hunter, Skyler C.; Bult-Ito, Abel; Taylor, Barbara; Podlutsky, Andrej; Vayndorf, Elena (2018-12)
      The purpose of this work is two-part. The primary goal of this thesis is to identify a list of significant target insulin-like peptides (ILPs) that influence the maintenance of neuronal morphology in an aged animal model of Caenorhabditis elegans (C. elegans) and determine whether or not morphological changes have bearing on neuronal function. The second goal is to address and devise a solution for a common laboratory difficulty encountered within the research community, difficulty maintaining large age-synchronous populations of the model organism, C. elegans. Chapter 1 discusses the importance of insulin signaling and how it pertains to the morphology of aging neurons. A reverse genetic screen was conducted to knockdown the expression of individual ILPs in a C. elegans model. The results identify a subfamily of ILPs that play significant roles in maintaining regular morphology of aging mechanosensory neurons. These data corroborate previously published work demonstrating that aberrant morphology of mechanosensory neurons does not directly influence their function and that these two parameters, morphology and function, can be uncoupled and considered mutually exclusive. Chapter 2 describes a main difficulty associated with using C. elegans as a model organism; the problem of maintaining a large age-synchronous population on solid media. To address this difficulty a novel piece of equipment, named the Caenorhabditis Sieve, and an accompanying methodology for its application, were created to mechanically sort and clean C. elegans. The use of this new device facilitates the implementation of assays with animals cultivated on solid media that are normally cost and resource prohibitive. Presented with the protocol for device construction and implementation, are standard experiments that were conducted to verify "proof of concept" of the tool's efficacy. The results demonstrate that the Caenorhabditis Sieve effectively transfers animals from one culture plate to the next in a manner that does not influence common markers of physiological stress; thus validating the sieve's use in future experiments among the research community, as well as highlighting the success of creating a cost-effective, efficient, fast, and simple process to mitigate difficulties and ease progress in research fields using small model organisms.
    • A study on the morphology of magnetic storms

      Sugiura, Masahisa (Geophysical Institute at the University of Alaska, 1955-04-20)
      The morphology of magnetic storms that has been investigated by S. Chapman since 1918 was further extended with more material as regards both the number of storms and the number of observatories, Three hundred and forty-six magnetic storms having sudden commencements were selected for the years 1902 to 19^5- These 3^6 storms were classified by a new method based on the most notable characteristic of the stormtime variation observed in low and middle latitudes, namely, a worldwide diminution in the horizontal force; hence the maximum diminution in the horizontal force averaged over these latitudes was used as a measure to indicate the intensity of magnetic storms. The 3^6 storms here selected were classified into three intensity groups: (l.) weak, (2) active, and {3 ) great storms.. The numbers of storms classed in these categories are 136, 136 and kj, respectively. In the present thesis the investigation on the 136 weak magnetic storms is described. (in the previous study made by Chapman forty storms of moderate intensity were used.) The number of magnetic observatories used in, the present study was also widely extended from eleven (in the previous work) to twentyfive. Seven observatories in the southern hemisphere distributed between geomagnetic latitudes 12° and 48° were included in these twentyfive observatories„ The geomagnetic latitudes of the eighteen northern observatories range from 20° to 80°, Several improvements were also made in the treatment of the magnetic data. One of the improvements is that hour-to-hour differences derived from the hourly values of the three magnetic elements, the horizontal force, declination and the vertical, force, were used, instead of the ordinary hourly values as given in observatory reports. With the 136 weak magnetic storms the storm-time variations of the three elements for the four pre-storm hours and the first seventy-two hours from the storm commencement were determined for eight groups of observatories, whose mean geomagnetic latitudes are 28° S, 21°, 28°, k2°, 52°, 59°, 65° and 80°; the first group being in the southern, the rest in the northern hemisphere. Thus the average features of the storm-time variations at various latitudes were able to be studied more closely. In determining these storm-time changes the daily variations on quiet days uncorrected for the non-cyclic variation were removed from the original data in order to allow for this latter variation. Then the disturbance local-time inequality for the first, second and third storm days was examined for each magnetic element for each of the groups of observatories. The vectograms of these variations were also drawn. Besides confirming, on the whole, the views expressed in Chapman's discussions on the storm-time as well as the disturbance local-time inequality, the present results revealed more detailed features of these variations at various latitudes. The disturbance local-time inequality for each element for each group of observatories was further studied for shorter intervals of storm-time, that is, for four 6-hour intervals in each of the first and second days and for three 8-hour intervals in the third storm day. The results were harmonically analyzed to determine the diurnal (2^-hour) and the semi-diurnal (12-hour) components of these variations. The diurnal component was illustrated by harmonic, dials, by which means the decay of the amplitude of these variations and the change of their phases with storm-time were clearly demonstrated. It was found that the phases of the disturbance diurnal equality in declination and the vertical force have certain definite relations with that in the horizontal force at each latitude, and that if the results for declination and the vertical force are combined -with those for the horizontal force with some appropriate modifications in their amplitudes and phases, and if such averages are further combined among the groups of observatories in low and middle latitudes, the averaged harmonic dial so obtained is much more regular than those for individual elements or for smaller groups. The rates of growth and decay of the storm-time change and the disturbance local-time inequality were compared., The results indicate that these two variations vary at rates that are materially different in their course. Detailed descriptions and discussions on these results, the final objects of the present study and plans for its future extension, are given in the present thesis.