The origin and geographical distribution of mammalian species (my examples are lemurs and bats) correlate with predictable chromosomal structural changes (KFT=karyotypic fission theory). Chromosome studies provide information about fertility between individuals and they are significant for identification of the geographical origin of reproductive isolation within mammal families. Each family predictably has chromosome sets with numbers that range from one to double the lowest number of chromosomes. The chromosome numbers of all species within a single family are used to reconstruct that family's evolutionary geographical dispersion. Polymorphic chromosome numbers (that is a range such as 34, 35, 36, 37, and 38) in a single population indicate the location where chromosomal diversification arose. Chromosome numbers of descending order correlate with relative distance from fission epicenters as the fissioned chromosomes gradually spread to neighboring populations. Furthermore, the location of chromosomal diversification (that is "karyotypic fission events) is associated with geographical "zones of transition" (after Professor R.W. Wilkie). My analysis, mapped one (Lepilemuridae) of the five families of lemurs (Class Mammalia, Order Primates, sub-order Lemuridae). The origin of this family's diversification is here hypothesized to have occurred at an ecological transition zone in Northern Madagascar between a humid evergreen-forest that extends to the East relative to a dry deciduous forest along the West Coast. My analysis of Vespertilionidae (insectivorous bats representing one third of all bat species) suggests a diversification event occurred in Asia; South China. Geographical distribution is important in the formation of biological diversity. A single species can inhabit a wide range and exhibit great diversity that is brought about by natural selection. The Holarctic reindeer found in Scandinavia, Russia, China, Canada and Alaska (including caribou) are all a single species Rangifer tarandus that exhibits variation in size and in coat pattern, changes brought about by adaptive selection by the environment or human selective breeding but they all have 70 similar chromosomes and they are all reproductively compatible. There is a single species of reindeer. Although, there is measurable DNA sequence divergence; there has been no "speciation" as these circumpolar cervids are genetically compatible.

<p> Microbial mat aggradation and morphology can be strongly influenced by sedimentation and light in ice-covered lakes of the McMurdo Dry Valleys, Antarctica. In Lake Joyce, mats transitioned from prostrate with widely spaced pinnacles to having densely spaced pinnacles with complex webs and ornamentation at greater distances from inflowing melt water streams. This transition is interpreted to result from decreasing mud sedimentation, which compacted delicate microbial structures such as pinnacle tips, webs, and surface ornamentation. Mud sedimentation also changed through time at sites adjacent to inflowing streams on one of the Lake Joyce deltas; sedimentation likely increased from 1947 through 2009 as lake levels rose. Although mud sedimentation demonstrably affected mat morphology in Lake Joyce, changes in sand and mud sedimentation associated with overhanging rocks in Lake Vanda were not sufficient to dramatically change mat morphology. Instead, microbial mat pinnacles and ridges had a variety of morphological responses to their light environment. Microbial mats growing with oblique directional light both grew down from overhanging rocks with pinnacle orientation independent from the directional light and grew up from the rock-sheltered mat with pinnacles and ridges oriented relative to incident light: asymmetrical pinnacles were inclined toward and flattened perpendicular to the incident light, and ridges were oriented parallel to the incident light. Changes in mat morphology and microbial processes are also preserved in Lake Joyce stromatolites that grew over decades. Stromatolites contain ?13Ccalcite records of variable photosynthetic fractionation of local DIC under lower lake levels, followed by decades of DIC pool 13C enrichment with lower rates of photosynthesis during lake level rise. These results demonstrate that microbial responses to their environments are complex and under the right conditions can be preserved in the rock record.</p>

<p> The mesic forests distributed within the Rocky Mountains of northern Idaho are unique because many species contained within the forest are separated from their main distribution along the Pacific Northwest coast. It remains unclear whether most species within the inland disjunction survived the glacial periods of the Pleistocene, or whether they were more recently dispersed from coastal populations. To see if the dominant tree taxa of the mesic forests today could have persisted in a refugium south of the large ice sheets, four sediment cores were used to reconstruct the vegetation and climate history of the region. A nearly continuous record of pollen and sediment composition (biogenic silica and inorganic and organic matter) over the last ca. 120,000 years provides evidence of a dynamic ecosystem. Over a long timescale, the slow shifts in vegetation are attributed to the changes in climate. During the last interglacial period, the region was warmer and drier with a <i> Pinus</i> dominated mixed conifer forest. Approximately 71,000 years ago, a <i>Pseudotsuga/Larix</i> forest became established in the area as a response to the increased available moisture. As climate cooled and glaciers expanded the <i>Pinus</i> and <i>Picea</i> forest was the dominant vegetation type until ca. 40,000 years ago. The environment during the Last Glacial Maximum (LGM) was so harsh that no vegetation record was recorded. After the LGM, climate warmed, enabling a Pinus and Picea forest to establish and persist until the Holocene.</p><p> The mesic taxa that dominate the modern forests did not arrive in northern Idaho until the mid- to late-Holocene. The recent arrival of the dominant tree species, <i>Thuja plicata</i> and <i>Tsuga mertensiana, </i> suggests that they likely did not persist in a refugium during the last glaciation. Instead, these species recently dispersed from coastal populations, but expansion into their interior distributions was likely limited by both climate and species competition in already established forests. During the late-Quaternary, the deposition of thick tephra layers (>20 cm) from the eruptions of Glacier Peak (ca. 13,400 years ago) and Mt. Mazama (ca. 7,600 years ago) also facilitated an abrupt and persistent change in vegetation in northern Idaho.</p>

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<p> For over 3.5Ga microbial activities have profoundly altered planetary geochemistry. In particular, sulfur-cycling hydrothermal vent communities have been important players in shaping biogeochemistry and the habitability of Earth. However, the remote nature of deep-sea vents makes investigations challenging. Using the White Point (WP) shallow-sea hydrothermal vent field as a proxy, I employed molecular sequencing, fluorescent in situ hybridization (FISH) and ³⁵S-radiotracer assays to investigate the diversity and function of chemoautotrophic microbial mats. This study revealed a highly active and diverse sulfur-cycling microbial community. Potential epibiotic associations between sulfur-oxidizing (SOxB) and sulfate/sulfur-reducing bacteria (SRB) were identified using FISH. Comparative analyses of 16S rRNA sequences revealed the WP sulfur vent microbial mat community to be similar to deep-sea microbial communities from hydrothermal vents in a range of biotopes and lithologic settings and supported the relevancy of the WP hydrothermal sulfur-vent microbial mats as an excellent model for studying "thiobiotic" vent communities.</p>

<p>Rapid changes in Earth?s marine environment are sufficiently rare that the scope and consequences of these events cannot be inventoried without recourse to the stratigraphic record of deep pre-historic time. Traditional stratigraphy divides geologic time into a succession of coarse biozones ? uneven time bins, each recognized by distinctive index fossils and spanning several hundred thousand to even a few million years. This thesis uses the CONOP software to resolve sequences of global appearance and disappearance events at the species level across the late Cenomanian oceanic anoxic event (OAE 2) at a much finer resolution than traditional biostratigraphy. The resulting time-lines include information for the Aptian to Maastrichtian from 501 locations, 4,962 taxa, and 25,112 local last occurrences. This dataset is large enough to represent the global environment and to compensate for the inevitably patchy and incomplete record preserved at any one location. Six geographically widespread clades ? ammonites, calcareous nannofossils, dinocysts, benthic forams, planktonic forams, and radiolaria ? were analyzed; they span a range of trophic levels, composition and preferred habitat. Extinction pulses and intervals of falling diversity are not unique to OAE 2 or even uniquely severe. Several occur throughout the Albian-Santonian interval. The key is to monitor trends in diversification rate. OAE 2 is distinguished as a boundary between more positive (or equal in the ammonite case) and more negative diversification regimes. It may have been part of a general habitat deterioration or disturbance, but it would be too simplistic to describe it as a coordinated pelagic extinction event.

<p> Evidence from modern oceanography, climate simulations of future conditions, and paleoceanographic archives motivates the need to reconstruct Oxygen Minimum Zone (OMZ) changes during past events of abrupt climate warming and carbon system perturbation. This dissertation focuses on the loss of oxygen in the Eastern Pacific Ocean through the most recent deglaciation event, in order to understand the spatial magnitude of oceanic deoxygenation and to quantify disturbance and recovery dynamics in seafloor biodiversity. New evidence from a shallow post-glacial sediment core (MV0811-15JC) from Santa Barbara Basin, California, USA, demonstrates the remarkable shallowness of OMZ influence to within ~300 meters from the ocean surface during the recent deglaciation. This site confirms that paleoceanographic reconstructions of hypoxia from Santa Barbara Basin are a product of regional expansions and contractions of the OMZ. Microfossil archives of seafloor metazoans (Echinodermata, Arthropoda and Mollusca; >5,350 individuals) from site MV0811-15JC demonstrate the extreme sensitivity of seafloor metazoan communities to abrupt (&lt;100 year) deoxygenation of the Eastern Pacific, and expand known timescales of biological recovery by one order of magnitude, from &lt;100 years to >1,000 years. Molluscan communities provide a complex interpretive window with which to understand environmental change through the deglaciation. Chemosynthetic and symbiotic molluscs numerically dominate the faunal record, yet these extremophiles do not strongly co-occur, indicating the development of heterogeneous extreme environments as a result of hydrographic regimes and the development of sulfur oxidizing bacterial mats. These analyses reveal that previous deoxygenation events dwarf modern scales of ecological disturbance, and illustrate the role that climate and oceanographic change have in driving long-term successional oscillations in ocean ecosystems. More broadly, the global inventory of deglacial and post-glacial sediment records exhibits remarkable synchrony in reconstructing subsurface hypoxia, and reveals that OMZs across the entire Eastern Pacific margin expanded and intensified concurrently. Most strikingly, these results uncover the capacity for large contiguous swaths of the ocean interior to rapidly lose dissolved oxygen, resulting in the expansion of OMZ ecosystems and the compression of surface ocean oxygenated ecosystems. Climate-forced changes to ocean systems introduce a scale of environmental disturbance that only has analogue in the rapid warming events of past climates. These critical analogues serve to illustrate the scale and ecological consequences of climate-forced deoxygenation.</p>

This dissertation research aims to show that there are deterministic microbial distribution patterns based on quantifiable environmental thresholds by determining and rationalizing the relative abundances of hyperthermophilic methanogens, autotrophic iron(III) oxide reducers, and heterotrophic sulfur reducers within deep-sea hydrothermal vents. Organisms of these metabolisms are predicted to be relatively more abundant in different regions depending on environmental conditions such as reduction potential, organic carbon, and hydrogen availability. The relative abundances of these metabolic groups within samples from the Endeavour Segment and Axial Volcano in the northeastern Pacific Ocean were determined. Iron(III) oxide reducers were detected in nearly all samples while methanogens were generally not present or present in concentrations lower than those of the iron(III) reducers. To determine growth constraints and the effect of hydrogen concentration on hyperthermophilic methanogen growth kinetics, Methanocaldococcus jannaschii and two new Methanocaldococcus field isolates were grown at varying hydrogen concentrations. The hydrogen-dependent growth kinetics for all three strains were statistically indistinguishable, exhibiting longer doubling times and lower maximum cell concentrations with decreasing hydrogen concentrations until growth ceased below 17–23 µM. This minimum hydrogen concentration for hyperthermophilic methanogenesis was correlated with field microbiology and fluid geochemistry data from the Endeavour Segment and Axial Volcano. Anomalously high methane concentrations and thermophilic methanogens were only observed in fluid samples where hydrogen concentrations were above this predicted threshold. Aside from anomalous sites, methanogens are predicted to be hydrogen limited, and may rely on hydrogen produced by heterotrophs as suggested by in situ sampling and co-culture experiments. Models and kinetic experiments suggest that iron(III) oxide reducers are not hydrogen limited under the same conditions. A Methanocaldococcus strain that we isolated from Axial Volcano and used in our hydrogen threshold experiments was bioenergetically modeled over its range of growth temperatures, pH, NaCl concentrations, and NH4Cl concentrations. Its methane production rates and growth energies were largely constant but increased at superoptimal temperatures and when nitrogen was limiting. The results of this research demonstrate that the rates of and constraints on metabolic processes can be used to predict the distribution and biogeochemical impact of hyperthermophiles in deep-sea hydrothermal vent systems.