Natural History Research Experiences
Research Training Program 2008
This research was supported by grants and donations to the Research Training Program.
Paleotemperature Estimates and Carbon Isotope Stratigraphy across the Cretaceous Supergreenhouse Interval in Tanzania
University of Wisconsin, Whitewater
Brian Huber, Ph.D.
Department of Paleobiology
Paleotemperatures and paleooceanographic characteristics from the geologic past can be derived by stable isotope mass spectrometry on foraminifera. Multiple foraminifera species, both benthic and planktic, were picked from the Tanzania Drilling Project (TDP) Site 22 and sent to be analyzed with a mass spectrometer. The 133 m sequence of clay-rich siltstone drilled at Site 22 spans ~2 million years within the Turonian Stage, Cretaceous Period (~93-91 million years ago). Oxygen isotope paleotemperatures estimated from high latitudes and mid-bathyal paleodepths have shown this time period to be extremely warm; however, reliable low latitude data have been almost nonexistent before this point. The reason behind this lack of data is the inherent lack of pristinely preserved (glassy) samples in the low latitudes, but clay-rich marine sediments found in southeast Tanzania provide rich foraminiferal assemblages that are perfectly preserved. Oxygen isotopic data show a temperature range of 29°C-34°C for planktic foraminifera (surface-dwelling), approximately 3°C-5°C higher than the average sea surface temperature today. The data also show variation throughout the 2 m.y. time period, with a temperature decrease at the beginning of the time period (deeper depth), peak in temperatures at a sample depth of 60 to 80 meters, and a temperature increase near the end of the time period (shallow depth). The vertical profile of planktic species show the biserial and unkeeled species as being the most shallow inhabitants, double-keel species being in the middle, and the single-keel species as being the deepest dwellers. The benthic (or bottom-dwelling) profile shows interspecies oxygen and carbon isotope offsets among Lenticulina, Hoeglundina, and Gavelinella species due to different vital effects. Carbon isotopic data show the expected distinction between the planktic and benthic foraminifera, with the surface-dwelling, planktic species being present in an area of more primary productivity. Results from this study support the hypothesis that significantly elevated levels of carbon dioxide caused warming at low and high latitudes during the Turonain “Supergreenhouse Event”. The understanding of this global warming event may provide insights to computer models representing past and future climatic trends.
Arizona State University
Ted Schultz, Ph.D.
Department of Entomology
The ant genus Pheidole is a hyper-diverse group found across six continents, with potentially over 1,000 species. Many of these ants exhibit worker dimorphism, that is, two morphologically different worker types (called major and minor workers) within single colonies. This, along with a wide assortment of morphotypes, makes identifying known, as well as unknown species, very difficult. The effectiveness of a relatively new method for species identification called DNA barcoding was evaluated both for associating worker morphotypes and identifying species in general. Leaf litter-dwelling Pheidole specimens from Guyana were collected and identified to species from morphology and then sequenced for the mtCOI barcode region. From these genetic data, it was found that DNA barcoding is a valuable tool for associating worker castes, as well as identifying new species. A major and minor worker from the species P. allarmata were successfully sequenced and were shown to be related not only from initial morphological identification, but from the genetic analysis as well, illustrating the value of DNA barcoding in associating worker castes. A total of 21 species were identified through morphology and 26 putative species were produced by the sequence data, showing a clear advantage to using DNA barcoding species identification along with morphological methods.
Comparative ontogeny of compound leaves: deciphering the enigmatic 3-parted leaf of the bishopwood tree (Bischofia; Phyllanthaceae)
Ana Marcela Florez
Universidad Industrial de Santander
Kenneth Wurdack, Ph.D.
Department of Botany
Compound leaves have convergently evolved many times in angiosperms but few comparative studies have been done on their origin and development. Based on leaf architecture, there are three main compound leaf types: pinnate, palmate, and ternate. Pinnate forms have leaflets attached along an elongate axis; palmate have more than three leaflets attached at a single point; and ternate are 3-parted (trifoliate) from a single point. The origins of ternate leaves are unclear without phylogenetic hypotheses and closely related pinnate or palmate taxa from which to determine the direction of any changes. For example, ternate leaves might be derived by reductions from pinnate or palmate forms. There also have been suggestions that ternate leaves might even represent a different pattern of development. The origins of compound leaves can be revealed through their early ontogeny and the study of mutant leaves. This study focuses on the bishop tree (Bischofia javanica), the only compound-leaved Phyllanthaceae (formerly part of Euphorbiaceae s.l.), which has an unusual, slightly asymmetrical, ternate leaf with small domatia and theoid teeth. A pinnate derivation was previously proposed, based on limited 5-foliolate leaf mutants. The structure and development of Bischofia leaves was examined with SEM and histological observations of young shoot tips, and compared with the early ontogeny of other taxa (i.e., ternate Rhus aromatica, Staphylea trifolia, and Staphylea holocarpa and palmate Joannesia princeps). In Bischofia and Staphylea holocarpa, mutant mature leaves were found with mixed multi-leaflet pinnate and palmate forms. Development of extra leaflets in the latter taxon was acropetal in the manner of pinnate leaves. The leaves of Bischofia showed no further axis growth after the near simultaneous initiation of the lateral leaflets. Laminar domatia in Bischofia did not reveal any secretory regions that might indicate a reward for the mites they putatively house.
University of Virginia
Michael Wise, Ph.D.
Department of Mineral Sciences
Blue quartz has been identified in literature dating as far back as 1884. However, few studies have been conducted to discern the geological significance of its occurrence. Although rarely reported in the world, it is not uncommon to find blue quartz in certain regions of the United States. Nine samples of blue quartz were analyzed from localities in: Old Rag Mountain, VA (2), Flint Hill, VA (2), Roseland, VA, Cape Ann, MA (2), Oracle, AZ, and Llano, TX. Scanning electron microscope images revealed the presence of rutile needles in quartz in all six localities. However, the size of these needles (2-30 µm) makes them unlikely candidates for the Rayleigh scattering of light. Thus, the origin of blue color remains unresolved. Thin sections of blue quartz from Old Rag Mountain showed rutile needles predominantly oriented at 60° to each other, which is consistent with the hexagonal crystal system of quartz suggesting rutile exsolved from the quartz. Blue quartz occurs in host rocks of varying composition (quartz monzonite to anorthosite to syenogranite gneiss) and age (1450 m.y. to 388 m.y.) amongst the studied localities. Some researchers suggested that blue quartz could be used an indicator for regional metamorphism, while others suggest that blue quartz is restricted to granitic rocks. Our research revealed that blue quartz is more closely associated with anorogenic granite magmatism. Further studies should aim to resolve the geologic conditions at which rutile can exsolve from quartz. Recent studies have suggested titanium substitutions in quartz are temperature dependent (Wark and Watson, 2006); thus, attention should be given to the titanium-bearing blue quartz as a potential geothermometer.
Bryn Mawr College
Bryn Mawr, Pennsylvania
Ives Goddard, Ph.D.
Department of Anthropology
This research examined phonological properties of the Algonquian language Unami, whose last speaker died in 2000. The purpose was to provide technical analysis of recordings using computer software that was not readily available at the time of the original field research (1966-1970). A freeware program (Praat) was used to analyze sound clips from digitized sound files of texts and word lists. Contrasts between phonemic short and phonemic long (geminate) consonants, specifically t, s, x, and š, were examined. (Phonemes are the minimal units of sound that contrast in a particular language and can therefore distinguish words.) For this research, the duration of the consonant (for the fricatives) and the duration of the stop closure (for t) were measured. It was discovered that there was no direct correlation between measurable duration and phonemic length. While most of the instances patterned such that the phonemic long consonants had longer durations than the phonemic short consonants, there was overlap in the mid-range values and there were several outliers. Patterns in sentence intonation (prosody) were also identified and described. In comparing the pitch contours of a variety of sentences, it was seen that these patterns did not always correlate with syntactic boundaries. This is evidence that it is possible for prosodic features to function at least partially independently from the grammar, which suggests the hypothesis that prosody can in part play a role in integrating discourse structures involving more than one sentence. Both the consonant length and sentence intonation data provide evidence for the complex relationship between linguistic structures and the phonetic features that express them. Further investigation of these features is required to fully understand how they function.
Hybrid or Species: Unraveling the Taxonomic Status of Murdannia discreta (Commelinaceae), A Rare Plant from Thailand
University of California, Berkeley
Robert B. Faden, Ph.D.
Department of Botany
Murdannia (Commelinaceae) is a pantropical monocot genus that is comprised of nearly 50 species. Morphologically, the genus is characterized by leaves that are arranged in a spiral, a sessile lamina, and a supervolute unfolding pattern (Faden, 1998). Its most distinctive feature is the presence of 3 fertile stamens attached in front of the sepals alternating with 3 sterile stamens (staminodes) attached in front of the petals. Anatomically, Murdannia shows much variation, but some of the similarities include the presence of a nearly continuous hypodermis, patterned cuticle, and marginal sclerenchyma (Faden & Inman, 1996). Murdannia discreta, a rare plant that is nearly endemic to Thailand, resembles two widespread Asian species, M. edulis and M. japonica based on a comparison of ten morphological characters (Thitimetharoch et al., unpublished). This research aims to determine whether M. discreta is a distinct rare species or a possible hybrid between M. edulis and M. japonica. Using a mixture of traditional and modern techniques, plants from six populations of the three taxa (3 M. edulis, 1 M. discreta, 2 M. japonica) were compared in leaf anatomy, morphology, chromosomes, and flowering times. Thin leaf cross sections and scanning electron microscope (SEM) images do not reveal important differences between the plants while preliminary chromosome counts suggest a close relationship of all three taxa. Overlapping flowering times of the plants in the afternoon confirms the feasibility for hybridization to occur between M. edulis and M. japonica. Although the information collected from these observations are valuable, DNA sequences will ultimately be included in the study, further clarifying the relationships among these three taxa.
Appalachian State University
Boone, North Carolina
Matthew Carrano, Ph.D.
Department of Paleobiology
The Fox Mesa locality is an unusual microvertebrate site in the Morrison Formation (Late Jurassic) of Wyoming because it includes embryonic dinosaur bone and hundreds of thousands of eggshell fragments, but a paucity of aquatic taxa. Fossil embryos with eggshell are rare and poorly understood, especially in the Morrison, making this site a unique opportunity to study the reproductive biology of a specific taxon, and thus learn more of this long gone world. The Fox Mesa site was mapped and bulk sampled in blocks (in 1999, 2001, 2003, and 2006). Body fossils and eggshell fragments were sorted by block. The site was buried in a floodplain mudstone typical of the Morrison Formation, and the eggshell and bones are very poorly sorted and well preserved. Analysis of the embryonic body fossils reveals a large number of elements assignable to Theropoda. Specifically, some of the jaws preserve minute (< 1 mm) coelurosaur-like teeth, and cervical vertebrae exhibit characteristic evidence of pneumaticity. It is not yet clear whether this represents a known Morrison coelurosaur, or a new taxon. Diagenic calcite is present on the eggshell surfaces, and the eggshell surfaces are all of a low, uniform curvature with some being "inside out". Surface morphology is therefore uninformative. In order to identify potentially informative microstructural features, and to test whether all the eggshells were from the same taxon, fragments from different blocks were embedded in epoxy and thin-sectioned. These thin-sections were analyzed under transmission, polarized light, and cathodoluminescent light microscopes. Fractured radial sections and acetic-acid-etched, polished sections of shells were imaged under an environmental scanning electron microscope. The ultrastructure of the eggshells preserves the following theropod synapomorphies: 1) both oblique and vertical tubular pore canals, 2) an unevenly upward-grading mammillary layer of acicular cystals, 3) a single, continuous second layer, and 4) a possible third, external layer. The thousands of eggshell fragments and hundreds of embryonic bones suggest an original life association. The concentration of fragments implies that this was either a continual nesting ground for these theropods, or that a large group of theropods all nested together. Either situation represents a unique window into this Jurassic ecosystem. Study of the Fox Mesa eggshell fragments has shown possible evidence for a new early coelurosaur, and opened up the study of reproductive strategies in Morrison theropods by assigning this eggshell type to a coelurosaur. Also, either explanation for the vast quantities of egg at the site—group nesting behavior or perennially occupied nests—is a rare phenomenon in non-avian theropod dinosaurs, previously discussed at only one other site in Portugal.
University of Pittsburgh
J. Daniel Rogers, Ph.D.
Department of Anthropology
Sustainability has always been a central factor in the long tradition of a nomadic pastoralist lifestyle in the Mongolian steppes. To understand how social complexity has developed in the region since the Bronze Age, it is necessary to examine the dynamics of the human-environment relationship. We used an agent-based simulation model called HouseholdWorld, developed by scientists at George Mason University in conjunction with archaeological research conducted by the National Museum of Natural History, to explore the interplay between ecology, herds, and humans in Mongolia. To better understand the human-environment dynamic, extreme weather events were researched and recreated in our model as a means of exploring adaptive capacity. Results indicate the importance of mobility and the delicate balance between the social and genetic benefits inherent in forming culture groups as opposed to problematic population clusters and competition for forage.
Diversification of Wellerellinae brachiopods during the West Texan Permian: A combined phylogenetic and morphometric approach
Peter Wagner, Ph.D.
Department of Paleobiology
The diversity of life has long fascinated scientists. The theory of natural selection provides a unifying framework in which to consider the evolution of diversity through time; however, consensus is still lacking in our understanding of how organisms have explored their potential morphospaces in such a way to produce the plethora of species on Earth. The idea of a theoretical morphospace, and adaptive landscapes therein, provides quantitative rigor in addressing questions of how morphologic diversity evolves. But here again little consensus exists, even on model predictions of evolution given assumed adaptive scenarios. In the current project we seek to bring a phylogenetic perspective to the question of diversification within a theoretical morphospace, namely a generalized morphospace for pseudo-logarithmically expanding shells, in order to test hypotheses about how diversity evolves, whether it is similar to random diffusion, driven by adaptive "basins of attraction," or the result of genetic and developmental constraints on organism structure. Here we present preliminary results achieved towards this goal. Specifically, a phylogenetic tree based on 35 discrete morphologic multistate characters and stratigraphic occurrence was recreated for 46 species in the subfamily Wellerellinae (Brachiopoda: Wellerellidae). These species largely originated and went extinct in the Permian of West Texas. Change in whorl expansion rate was also calculated. The generalized morphospace will be forthcoming, as will an analysis of support for three different models of evolution: (1) evolution is the result of random diffusion, (2) evolution is driven by basins of attraction within the morphospace (i.e. adaptive peaks), and (3) genetic and developmental constraints determine extent and direction of diversification.
Universidad de Los Andes
R. Terry Chesser, Ph.D.
Department of Vertebrate Zoology, Birds
Cinclodes fuscus is a widespread and common species of ovenbird (Furnariidae) that breeds from Tierra del Fuego to the northern Andes. Traditionally, C. fuscus has been considered a single species composed of nine subspecies, and its long and narrow range suggests the possibility of considerable genetic variation among populations. We used two mitochondrial genes to reveal discrete and geographically coherent groups of Cinclodes fuscus; surprisingly these groups were more closely related to other species of Cinclodes than to each other. We also found evidence for incomplete lineage sorting or hybridization between C. oustaleti and one group of C. fuscus.
Differentiation of Broad-clawed Shrews, Cryptotis griseoventris and C. goodwini, Based on Bone Forefoot Morphology
University of Wisconsin, Stevens Point
Stevens Point, Wisconsin
Neal Woodman, Ph.D.
Department of Vertebrate Zoology, Mammals
Five species of broad-clawed shrews occur in Mexico and Central America. Two of these, Cryptotis griseoventris and C. goodwini, occur in close proximity to each other and can be extremely difficult to differentiate because they have few cranial differences. In the past, size was the primary characteristic used to differentiate the two species, which were known from relatively few localities in Mexico and Guatemala. To find out more about these two species, new specimens are being collected from additional localities. With these new specimens, size is no longer as useful in determining species because many specimens are of an intermediate size. The forefeet of these shrews have been shown to be useful in differentiating among taxa of shrews. We used digital x-ray technology to obtain images of the forefoot bones of 13 C. goodwini from the type locality in Calel, Guatemala, 8 C. griseoventris from the type locality in Chiapas, Mexico, 17 C. griseoventris from a second locality in Guatemala, 11 new specimens treated as unknowns, and 5 older specimens from other localities that were also treated as unknowns. Lengths and widths of phalanges, metacarpals, and claws were measured from digital images and recorded for digits I, III, and V of the forefoot of each specimen. These data were analyzed to establish which measurements and combinations of measurements were most useful in differentiating between C. griseoventris and C. goodwini. We then used these measurements to determine whether the two populations of C. griseoventris could be distinguished and whether they could be used to classify the unknowns. Widths of bones alone and in combination are most useful for differentiating between the two species and for identifying unknown specimens, while lengths were not as useful because there was a large amount of overlap between the two species. In general, C. goodwini has proportionally wider phalanges and metacarpals than C. griseoventris. We also found that the population of C. griseoventris from Chiapas had smaller forefeet than those of Guatemala. These findings may be used to learn more about shrew ecology and biology.
Differentiating Two Putative Nemertean Species, Lineus ruber and Lineus viridis: Comparison of Mitochondrial Gene Cytochrome C Oxidase Subunit 1 (COI)
University of Delaware
Jon Norenberg, Ph.D.
Department of Invertebrate Zoology
Lineus ruber and Lineus viridis, two nemerteans found essentially sympatrically along both northeastern and northwestern Atlantic coastal habitats have long been considered synonymous by many researchers. While differences include color, habitat elevation and larval development, past work with 16S rDNA sequence data showed about 3% genetic divergence for the two nemerteans, marginal for separating species. Results from preliminary maximum parsimony phylogenetic analysis of cytochrome c oxidase subunit I gene sequences from the two putative species and Riseriellus occultus strongly indicate that Lineus ruber and Lineus viridis are two different species. Average intraspecific sequence divergences for L. ruber and L. viridis were 3.65 and 1.45% respectively, while interspecific divergences were at least 12.25%. Further analysis of sequences offers additional information and guidance for future phylogenetic and population genetics research.
Determining the phylogenetic significance of variation in the female frenulum in Chlidanotinae (Lepidoptera: Tortricidae)
University of California, Berkeley
John Brown, Ph.D.
Department of Entomology
This study, treating the tortricid subfamily Chlidanotinae, represents the first in a proposed three-part series examining variation in the number of spines in the frenulum of female tortricid moths. Based on an examination of 113 described species and 14 undescribed species representing 37 genera of Chlidanotinae, the vast majority of females of Chlidanotini and Hilarographini have a 2-bristled frenulum, whereas a 3-bristled frenulum is the more common state in Polyorthini. When the character states are mapped on a composite phylogeny of the subfamily, the change from 3 to 2 bristles appears to have evolved once at the base of the Chlidanotini + Hilarographini clade. However, this character is considerably more variable within Polyorthini. Two bristles were observed in the vast majority of females of Ardeutica, Polyortha, Pseudatteria, Polythora, Cnephasitis, and Ebodina. Three bristles were observed in most species of Isotrias, Histura, Histurodes, Lypothora, Lopharcha, and Polylopha. In Olindia schumacherana, five of 18 representatives examined had 2 bristles and the remainder had 3. The distribution of bristles within Polyorthini seems to supports certain clades as previously suggested by Razowski. However, there are numerous minor deviations from this pattern, putatively representing independent evolution of the 2-spine state. Variation in the number of spines in the frenulum of tortricid moths may be phylogenetically informative at some levels and within some taxa, but too variable to be useful in others.
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