Paleobiogeography of the North American Late Cretaceous Western Interior Seaway: the impact of abiotic vs. biotic factors on macroevolutionary patterns of marine vertebrates and invertebrates

My research investigates the relationship between ecology, evolution, and the environment in the fossil record. I hypothesize that abiotic environmental factors (e.g., climate, sea-level, ocean chemistry, and paleogeography) play a greater role in speciation, extinction, and distribution patterns than biotic factors (e.g., competition, mutualism). The effects of these factors can be observed in the fossil record as changes in species distributions, range sizes, and niche dimensions through time. Using GIS, paleoenvironmental reconstruction, and ecological niche modeling (ENM), I quantitatively investigated hypotheses of the relative influence of abiotic vs. biotic factors on macroevolution in three main studies of marine taxa from the Late Cretaceous Western Interior Seaway (WIS) of North America. The Late Cretaceous was a period of prolonged extreme and equable warmth; thus, this research has potential implications for species biology and biogeography in a projected future warmer world. The first study examined the influence of biotic interactions on patterns of extinction by competitive exclusion in marine vertebrates. Results indicated that competitive replacement was not a mechanism mediating extinctions. Instead other factors, such as environmental changes, likely controlled extinction patterns. The second study investigated the effect of large range size on survivorship and invasion potential in marine mollusks. No relationship between large range size and extinction resistance was recovered, however, endemic species with small range sizes were more likely to become invasive. These results suggest that some biogeographic "rules" (e.g., large range size confers extinction resistance and increased invasion potential) may not prevail under conditions of prolonged and equable global warmth. The last part of my research focused on improving methods for the application of ENM in the fossil record (paleo-ENM). In order to use ENM in the fossil record, detailed environmental layers must be reconstructed from sedimentological and geochemical proxies. Additionally, paleo-ENM requires high-resolution stratigraphic correlations of fossil-bearing formations and collection of large species' occurrence datasets that represent the full temporal and spatial extent of the species modeled. In order to produce high fidelity models, a standardized framework for paleoenvironmental reconstruction is required. Best practices are outlined for paleoenvironmental reconstruction, in addition to the contextual framework and important considerations necessary to appropriately apply paleo-ENM

Floral Resource Availability and Butterfly Community Characteristics in CP-42 Pollinator Habitat Plantings

Prairies once covered approximately 85% of Iowa, but due to extensive habitat loss less than 0.1% of native prairies remain (Smith 1998). Habitat loss in Iowa has been driven by agricultural expansion and intensification, and has resulted in the decline of many native insect pollinators. To curb habitat loss and restore habitat for pollinators, USDA’s Farm Service Agency (FSA) provides private landowners incentives to enroll agricultural land into the Conservation Reserve Program (CRP) Pollinator Habitat (CP-42) practice. The CP-42 conservation practice requires landowners to seed at least 9 species of pollinator friendly wildflowers, legumes, or shrubs on enrolled lands. CP-42 seed mixes must include least three species during each of three bloom periods (April-June 15, June 15- July, and August-October) (USDA 2011). About 50% of all CP42 acres are seeded in Iowa (USDA 2018). We have developed methods for evaluating floral resources and habitat quality for butterflies at CP-42 sites in central Iowa. Our study will produce data to assess the quality of habitat produced by the CP-42 program and to provide information about the effectiveness of the CP-42 program to Farm Service Agency

RELATIONSHIP BETWEEN INITIAL ENVIRONMENTAL CONDITIONS AND BIOTIC EXTINCTION EVENTS FROM THE LAST ~540 MILLION YEARS

Extinction has occurred throughout Earth history, with most of the focus on the largest in magnitude from the last ~540 million years (Myrs), or the Phanerozoic Eon. Extinction science has concentrated on the trigger and the recovery of these events. The largest extinctions have been linked to abiotic environmental forcing (e.g. massive volcanic events, extraterrestrial impacts, or climate change) that drove biota to extinction. Here, we investigate the impact initial environmental conditions had on elevated Phanerozoic extinction rates of marine genera. To test hypotheses of how specific initial conditions of abiotic environmental factors may have impacted extinction rates, we compiled a ~540 Myrs record of five environmental proxies and two published marine faunal extinction rate datasets (Bambach 2006 and Alroy 2014) from an extensive literature review. The environmental proxies tested include: δ18O and δ13C stable isotopic records (climate variability), 87Sr/86Sr record (continental weathering rates), eustatic sea level (variability in area of shallow shelf habitat), and continental shelf area (habitable area). All proxies were subset to 2, 5, and 10 Myrs-prior bins, intervals of time, to test for time bin sensitivity. Multiple linear regression analysis was used to test our hypotheses and to estimate the relationship between environmental factors (individually and in concert) and extinction rates during 18 and 16 key intervals of elevated extinction identified by Bambach (2006) and Alroy (2014), respectively. We find all six models, except the Alroy 5 Myrs-prior model, to weakly estimate the relationship between environmental proxies and extinction rates, and poorly explain the variation in extinction rates (\u3c40%-60%). The Alroy 5 Myrs-prior model is statistically significant (p=0.001) and explains 78% of the variation in elevated extinction rates. Climate variability and continental weathering rates were the environmental proxies that contributed most to the Alroy 5 Myrs-prior model. Our findings provide evidence that the most elevated extinctions may have been preconditioned for high extinction magnitudes. Identifying the role that pre-existing conditions play in promoting or inhibiting periods of elevated extinction are important for improving our understanding of Phanerozoic macroevolution and may positively contribute to improving projections of the consequences of the current biodiversity crisis

Sharks That Pass In The Night: Using GIS to Investigate Competition in the Cretaceous Western Interior Seaway

This is the author's accepted manuscript, also available at http://dx.doi.org/10.1098/rspb.2010.1617One way the effects of both ecology and environment on species can be observed in the fossil record is as changes in geographical distribution and range size. The prevalence of competitive interactions and species replacements in the fossil record has long been investigated and many evolutionary perspectives, including those of Darwin, have emphasized the importance of competitive interactions that ultimately lead one species to replace another. However, evidence for such phenomena in the fossil record is not always manifest. Here we use new quantitative analytical techniques based on Geographical Information Systems and PaleoGIS tectonic reconstructions to consider this issue in greater detail. The abundant, well-preserved fossil marine vertebrates of the Late Cretaceous Western Interior Seaway of North America provide the component data for this study. Statistical analysis of distributional and range size changes in taxa confirms earlier ideas that the relative frequency of competitive replacement in the fossil record is limited to non-existent. It appears that typically, environmental gradients played the primary role in determining species distributions, with competitive interactions playing a more minor role

Geographic and temporal morphological stasis in the latest Cretaceous ammonoid Discoscaphites iris from the U.S. Gulf and Atlantic Coastal Plains

We examine temporal and spatial variation in morphology of the ammonoid cephalopod Discoscaphites iris using a large dataset from multiple localities in the Late Cretaceous (Maastrichtian) of the United States Gulf and Atlantic Coastal Plains, spanning a distance of 2000 km along the paleoshoreline. Our results suggest that the fossil record of D. iris is consistent with no within species net accumulation of phyletic evolutionary change across morphological traits or the lifetime of this species. Correlations between some traits and paleoenvironmental conditions as well as changes in the coefficient of variation may support limited population-scale ecophenotypic plasticity, however where stratigraphic data are available, no directional changes in morphology occur prior to the Cretaceous/Paleogene (K/Pg) boundary. This is consistent with models of 'dynamic' evolutionary stasis. Combined with knowledge of life history traits and paleoecology of scaphitid ammonoids, specifically a short planktonic phase after hatching followed by transition to a nektobenthic adult stage, these data suggest that scaphitids had significant potential for rapid morphological change in conjunction with limited dispersal capacity. It is therefore likely that evolutionary mode in the Scaphitidae (and potentially across the broader ammonoid clade) follows a model of cladogenesis wherein a dynamic morphological stasis is periodically interrupted by more substantial evolutionary change at speciation events. Finally, the lack of temporal changes in our data suggest that global environmental changes (such as those possibly related to the emplacement of the Deccan Traps Large Igneous Province) had a limited effect on the morphology of North American ammonoid faunas during the latest Cretaceous prior to the K/Pg mass extinction event.Missing morphometric values are highlighted with NA in the dataset.Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: 1924807Funding provided by: American Museum of Natural History and Richard Gilder Graduate School*Crossref Funder Registry ID: Award Number:We assembled a large morphometric dataset consisting of 328 individual fossil specimens of the scaphitid ammonoid cephalopod Discoscaphites iris collected from nine localities in Texas, Missouri, Mississippi, and New Jersey, representing a ~2000 km transect from SW to NE and encompassing the full geographic range of this species. Morphometric parameters were measured on well-preserved adult specimens of two dimorphs (Macroconchs - presumably the female, and microconch, presumably the male). We took up to seven morphometric measurements, and calculated ratios that captured the size, shape, and degree of compression of each of these ammonoid shells from each different locality. We evaluated the coefficient of variation (the standard deviation divided by the mean) for size and shape ratios as well as compression ratios at each locality. We used non-parametric statistical tests [Mann-Whitney U] to evaluate the significance of changes in mean morphological trait values between localities. To correct for multiple comparisons we applied a Bonferroni correction and also controlled for the false discovery rate. We also explored relationships between morphological traits and several environmental variables using linear modelling. All analyses were conducted in the R programming environment

Optimization of the Culture Medium Composition to Improve the Production of Hyoscyamine in Elicited Datura stramonium L. Hairy Roots Using the Response Surface Methodology (RSM)

Traditionally, optimization in biological analyses has been carried out by monitoring the influence of one factor at a time; this technique is called one-variable-at-a-time. The disadvantage of this technique is that it does not include any interactive effects among the variables studied and requires a large number of experiments. Therefore, in recent years, the Response Surface Methodology (RSM) has become the most popular optimization method. It is an effective mathematical and statistical technique which has been widely used in optimization studies with minimal experimental trials where interactive factors may be involved. This present study follows on from our previous work, where RSM was used to optimize the B5 medium composition in [NO3−], [Ca2+] and sucrose to attain the best production of hyoscyamine (HS) from the hairy roots (HRs) of Datura stramonium elicited by Jasmonic Acid (JA). The present paper focuses on the use of the RSM in biological studies, such as plant material, to establish a predictive model with the planning of experiments, analysis of the model, diagnostics and adjustment for the accuracy of the model. With the RSM, only 20 experiments were necessary to determine optimal concentrations. The model could be employed to carry out interpolations and predict the response to elicitation. Applying this model, the optimization of the HS level was 212.7% for the elicited HRs of Datura stramonium, cultured in B5-OP medium (optimized), in comparison with elicited HRs cultured in B5 medium (control). The optimal concentrations, under experimental conditions, were determined to be: 79.1 mM [NO3−], 11.4 mM [Ca2+] and 42.9 mg/L of sucrose

Nacre tablet thickness records formation temperature in modern and fossil shells

Nacre, the iridescent outer lining of pearls and inner lining of many mollusk shells, is composed of periodic, parallel, organic sheets alternating with aragonite (CaCO_3) tablet layers. Nacre tablet thickness (TT) generates both nacre's iridescence and its remarkable resistance to fracture. Despite extensive studies on how nacre forms, the mechanisms controlling TT remain unknown, even though they determine the most conspicuous of nacre's characteristics, visible even to the naked eye. Thermodynamics predicts that temperature (T) will affect both physical and chemical components of biomineralized skeletons. The chemical composition of biominerals is well-established to record environmental parameters, and has therefore been extensively used in paleoclimate studies. The physical structure, however, has been hypothesized but never directly demonstrated to depend on the environment. Here we observe that the physical TT in nacre from modern and fossil shallow-water shells of the bivalves Pinna and Atrina correlates with T as measured by the carbonate clumped isotope thermometer. Based on the observed TT vs. T correlation, we anticipate that TT will be used as a paleothermometer, useful to estimate paleotemperature in shallow-water paleoenvironments. Here we successfully test the proposed new nacre TT thermometer on two Jurassic Pinna shells. The increase of TT with T is consistent with greater aragonite growth rate at higher T, and with greater metabolic rate at higher T. Thus, it reveals a complex, T-dependent biophysical mechanism for nacre formation

Genome-Wide Control of the Distribution of Meiotic Recombination

Meiotic recombination events are not randomly distributed in the genome but occur in specific regions called recombination hotspots. Hotspots are predicted to be preferred sites for the initiation of meiotic recombination and their positions and activities are regulated by yet-unknown controls. The activity of the Psmb9 hotspot on mouse Chromosome 17 (Chr 17) varies according to genetic background. It is active in strains carrying a recombinant Chr 17 where the proximal third is derived from Mus musculus molossinus. We have identified the genetic locus required for Psmb9 activity, named Dsbc1 for Double-strand break control 1, and mapped this locus within a 6.7-Mb region on Chr 17. Based on cytological analysis of meiotic DNA double-strand breaks (DSB) and crossovers (COs), we show that Dsbc1 influences DSB and CO, not only at Psmb9, but in several other regions of Chr 17. We further show that CO distribution is also influenced by Dsbc1 on Chrs 15 and 18. Finally, we provide direct molecular evidence for the regulation in trans mediated by Dsbc1, by showing that it controls the CO activity at the Hlx1 hotspot on Chr 1. We thus propose that Dsbc1 encodes for a trans-acting factor involved in the specification of initiation sites of meiotic recombination genome wide in mice

A second horizon scan of biogeography:golden ages, Midas touches, and the Red Queen

Are we entering a new ‘Golden Age’ of biogeography, with continued development of infrastructure and ideas? We highlight recent developments, and the challenges and opportunities they bring, in light of the snapshot provided by the 7th biennial meeting of the International Biogeography Society (IBS 2015). We summarize themes in and across 15 symposia using narrative analysis and word clouds, which we complement with recent publication trends and ‘research fronts’. We find that biogeography is still strongly defined by core sub-disciplines that reflect its origins in botanical, zoological (particularly bird and mammal), and geographic (e.g., island, montane) studies of the 1800s. That core is being enriched by large datasets (e.g. of environmental variables, ‘omics’, species’ occurrences, traits) and new techniques (e.g., advances in genetics, remote sensing, modeling) that promote studies with increasing detail and at increasing scales; disciplinary breadth is being diversified (e.g., by developments in paleobiogeography and microbiology) and integrated through the transfer of approaches and sharing of theory (e.g., spatial modeling and phylogenetics in evolutionary–ecological contexts). Yet some subdisciplines remain on the fringe (e.g., marine biogeography, deep-time paleobiogeography), new horizons and new theory may be overshadowed by popular techniques (e.g., species distribution modelling), and hypotheses, data, and analyses may each be wanting. Trends in publication suggest a shift away from traditional biogeography journals to multidisciplinary or open access journals. Thus, there are currently many stewardship of, the planet (e.g., Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). As in the past, biogeographers doubtless will continue to be engaged by new data and methods in exploring the nexus between biology and geography for decades into the future. But golden ages come and go, and they need not touch every domain in a discipline nor affect subdisciplines at the same time; moreover, what appears to be a Golden Age may sometimes have an undesirable ‘Midas touch’. Contexts within and outwith biogeography—e.g., methods, knowledge, climate, biodiversity, politics—are continually changing, and at times it can be challenging to establish or maintain relevance. In so many races with the Red Queen, we suggest that biogeography will enjoy greatest success if we also increasingly engage with the epistemology of our disciplinePeer reviewe