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Item On the relationship between collagen- and carbonate-derived carbon isotopes with implications for the inference of carnivore dietary behavior(Frontiers In Ecology And Evolution, 2022-12-20) DeSantis, Larisa R. G.; Feranec, Robert S. S; Southon, John; Cerling, Thure E. E.; Harris, John; Binder, Wendy J. J.; Cohen, Joshua E. E.; Farrell, Aisling B. B.; Lindsey, Emily L. L.; Meachen, Julie; O'Keefe, Frank Robin; Takeuchi, Gary T. T.Studies of Rancho La Brea predators have yielded disparate dietary interpretations when analyzing bone collagen vs. enamel carbonate-requiring a better understanding of the relationship between stable carbon isotopes in these tissues. Stable carbon isotope spacing between collagen and carbonate (Delta(ca-co)) has also been used as a proxy for inferring the trophic level of mammals, with higher Delta(ca-co) values indicative of high carbohydrate consumption. To clarify the stable isotope ecology of carnivorans, past and present, we analyzed bone collagen (carbon and nitrogen) and enamel carbonate (carbon) of extinct and extant North American felids and canids, including dire wolves, sabertooth cats, coyotes, and pumas, supplementing these with data from African wild dogs and African lions. Our results reveal that Delta(ca-co) values are positively related to enamel carbonate values in secondary consumers and are less predictive of trophic level. Results indicate that the foraging habitat and diet of prey affects Delta(ca-co) in carnivores, like herbivores. Average Delta(ca-co) values in Pleistocene canids (8.7+/-1 parts per thousand) and felids (7.0+/-0.7 parts per thousand) overlap with previously documented extant herbivore Delta(ca-co) values suggesting that trophic level estimates may be relative to herbivore Delta(ca-co) values in each ecosystem and not directly comparable between disparate ecosystems. Physiological differences between felids and canids, ontogenetic dietary differences, and diagenesis at Rancho La Brea do not appear to be primary drivers of Delta(ca-co) offsets. Environmental influences affecting protein and fat consumption in prey and subsequently by predators, and nutrient routing to tissues may instead be driving Delta(ca-co) offsets in extant and extinct mammals.Item The Young Brickmakers(2020) Best, Kelsea B.In 2020, a young brickmaker (Kelsea Best) provides an update to B. K. Forscher's 1963 vision of the state of the scientific endeavor as a brickyard. As the brickyard becomes ever more chaotic, this essay calls on young brickmakers to begin to clear the clutter, focusing on the construction of edifices over piles of bricks.Item The Brickyard in 2020(2020) Furbish, David J.; Jerolmack, Douglas J.; Glade, Rachel C.The authors of this essay (David Furbish, Douglas Jerolmack and Rachel Glade) offer an updated view of the state of affairs in the brickyard described in B. K. Forscher’s popular 1963 allegorical letter to Science, “Chaos in the Brickyard.” It calls for a need to realign the research endeavor, institutions and incentives with changing values.Item Prominent Influence of Socioeconomic and Governance Factors on the Food-Energy-Water Nexus in sub-Saharan Africa(Earths Future, 2019-09) Ding, Ke Jack; Gunda, Thushara; Hornberger, George M.Food, energy, and water (FEW) are primary resources required for human populations and ecosystems. Availability of the raw resources is essential, but equally important are the services that deliver resources to human populations, such as adequate access to safe drinking water, electricity, and sufficient food. Any failures in either resource availability or FEW resources-related services will have an impact on human health. The ability of countries to intervene and overcome the challenges in the FEW domain depends on governance, education, and economic capacities. We distinguish between FEW resources, FEW services, and FEW health outcomes to develop an analysis framework for evaluating interrelationships among these critical resources. The framework is applied using a data-driven approach for sub-Saharan African countries, a region with notable FEW insecurity challenges. The data-driven approach using a cross-validated stepwise regression analysis indicates that limited governance and socioeconomic capacity in sub-Saharan African countries, rather than lack of the primary resources, more significantly impact access to FEW services and associated health outcomes. The proposed framework helps develop a cohesive approach for evaluating FEW metrics and could be applied to other regions of the world to continue improving our understanding of the FEW nexus.Item Selection on multiple sexual signals in two Central and Eastern European populations of the barn swallow(Ecology and Evolution, 2019-10) Wilkins, Matthew R.Variation in intensity and targets of sexual selection on multiple traits has been suggested to play a major role in promoting phenotypic differentiation between populations, although the divergence in selection may depend on year, local conditions or age. In this study, we quantified sexual selection for two putative sexual signals across two Central and East European barn swallow (Hirundo rustica rustica) populations from Czech Republic and Romania over multiple years. We then related these differences in selection to variation in sexual characters among barn swallow populations. Our results show that tail length and ventral coloration vary between populations, sexes, and age classes (first-time breeders vs. experienced birds). We found that selection on tail length was stronger in first-time breeders than in experienced birds and in males than in females in the Romanian population, while these differences between age groups and sexes were weak in Czech birds. We suggest that the populational difference in selection on tail length might be related to the differences in breeding conditions. Our results show that ventral coloration is darker (i.e., has lower brightness) in the Romanian than in the Czech population, and in experienced birds and males compared with first-time breeders and females, respectively. The sexual difference in ventral coloration may suggest sexual selection on this trait, which is supported by the significant directional selection of ventral coloration in first-time breeding males on laying date. However, after controlling for the confounding effect of wing length and tarsus length, the partial directional selection gradient on this trait turned nonsignificant, suggesting that the advantage of dark ventral coloration in early breeding birds is determined by the correlated traits of body size. These findings show that ventral coloration may be advantageous over the breeding season, but the underlying mechanism of this relationship is not clarified.Item Speleothem Paleoclimatology for the Caribbean, Central America, and North America(Quaternary, 2019-03) Oster, Jessica L.; Warken, Sophie E.; Sekhon, Natasha; Arienzo, Monica M.; Lachniet, MatthewSpeleothem oxygen isotope records from the Caribbean, Central, and North America reveal climatic controls that include orbital variation, deglacial forcing related to ocean circulation and ice sheet retreat, and the influence of local and remote sea surface temperature variations. Here, we review these records and the global climate teleconnections they suggest following the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database. We find that low-latitude records generally reflect changes in precipitation, whereas higher latitude records are sensitive to temperature and moisture source variability. Tropical records suggest precipitation variability is forced by orbital precession and North Atlantic Ocean circulation driven changes in atmospheric convection on long timescales, and tropical sea surface temperature variations on short timescales. On millennial timescales, precipitation seasonality in southwestern North America is related to North Atlantic climate variability. Great Basin speleothem records are closely linked with changes in Northern Hemisphere summer insolation. Although speleothems have revealed these critical global climate teleconnections, the paucity of continuous records precludes our ability to investigate climate drivers from the whole of Central and North America for the Pleistocene through modern. This underscores the need to improve spatial and temporal coverage of speleothem records across this climatically variable region.Item Spatiotemporal Patterns and Phenology of Tropical Vegetation Solar-Induced Chlorophyll Fluorescence across Brazilian Biomes Using Satellite Observations(Remote Sensing, 2019-08) Merrick, Trina; Pau, Stephanie; Jorge, Maria Luisa S. P.; Silva, Thiago S. F.; Bennartz, RalfSolar-induced fluorescence (SIF) has been empirically linked to gross primary productivity (GPP) in multiple ecosystems and is thus a promising tool to address the current uncertainties in carbon fluxes at ecosystem to continental scales. However, studies utilizing satellite-measured SIF in South America have concentrated on the Amazonian tropical forest, while SIF in other regions and vegetation classes remain uninvestigated. We examined three years of Orbiting Carbon Observatory-2 (OCO-2) SIF data for vegetation classes within and across the six Brazilian biomes (Amazon, Atlantic Forest, Caatinga, Cerrado, Pampa, and Pantanal) to answer the following: (1) how does satellite-measured SIF differ? (2) What is the relationship (strength and direction) of satellite-measured SIF with canopy temperature (T-can), air temperature (T-air), and vapor pressure deficit (VPD)? (3) How does the phenology of satellite-measured SIF (duration and amplitude of seasonal integrated SIF) compare? Our analysis shows that OCO-2 captures a significantly higher mean SIF with lower variability in the Amazon and lower mean SIF with higher variability in the Caatinga compared to other biomes. OCO-2 also distinguishes the mean SIF of vegetation types within biomes, showing that evergreen broadleaf (EBF) mean SIF is significantly higher than other vegetation classes (deciduous broadleaf (DBF), grassland (GRA), savannas (SAV), and woody savannas (WSAV)) in all biomes. We show that the strengths and directions of correlations of OCO-2 mean SIF to T-can, T-air, and VPD largely cluster by biome: negative in the Caatinga and Cerrado, positive in the Pampa, and no correlations were found in the Pantanal, while results were mixed for the Amazon and Atlantic Forest. We found mean SIF most strongly correlated with VPD in most vegetation classes in most biomes, followed by T-can. Seasonality from time series analysis reveals that OCO-2 SIF measurements capture important differences in the seasonal timing of SIF for different classes, details masked when only examining mean SIF differences. We found that OCO-2 captured the highest base integrated SIF and lowest seasonal pulse integrated SIF in the Amazon for all vegetation classes, indicating continuous photosynthetic activity in the Amazon exceeds other biomes, but with small seasonal increases. Surprisingly, Pantanal EBF SIF had the highest total integrated SIF of all classes in all biomes due to a large seasonal pulse. Additionally, the length of seasons only accounts for about 30% of variability in total integrated SIF; thus, integrated SIF is likely captures differences in photosynthetic activity separate from structural differences. Our results show that satellite measurements of SIF can distinguish important functioning and phenological differences in vegetation classes and thus has the potential to improve our understanding of productivity and seasonality in the tropics.Item Seeking enlightenment of fluvial sediment pathways by optically stimulated luminescence signal bleaching of river sediments and deltaic deposits(Earth Surface Dynamics, 2019-08-09) Chamberlain, Elizabeth L.; Walling, JakobReconstructing sediment pathways in fluvial and deltaic systems beyond instrumental records is challenging due to a lack of suitable methods. Here we explore the potential of luminescence methods for such purposes, focusing on bleaching of the optically stimulated luminescence (OSL) signal of quartz sediments in a large fluviodeltaic system across time and space. We approach this by comparing residual doses of sand and silt from the modern Mississippi River channel with estimated residual doses of sand isolated from Late Holocene Mississippi Delta mouth bar and overbank deposits. Further insight is obtained from a comparison of burial ages of paired quartz sand and silt of Mississippi Delta overbank deposits. In contrast to some previous investigations, we find that the bleaching of the OSL signal is at least as likely for finer sediment as for coarser sediment of the meandering Mississippi River and its delta. We attribute this to the differences in light exposure related to transport mode (bedload vs. suspended load). In addition, we find an unexpected spatiotemporal pattern in OSL bleaching of mouth bar sand deposits. We suggest this may be caused by changes in upstream pathways of the meandering channel belt(s) within the alluvial valley or by distributary channel and coastal dynamics within the delta. Our study demonstrates that the degree of OSL signal bleaching of sand in a large delta can be highly time-and/or space-dependent. Silt is shown to be generally sufficiently bleached in both the modern Mississippi River and associated paleo-deposits regardless of age, and silt may therefore provide a viable option for obtaining OSL chronologies in megadeltas. Our work contributes to initiatives to use luminescence signals to fingerprint sediment pathways within river channel networks and their deltas and also helps inform luminescence dating approaches in fluviodeltaic environments.Item Transstadial immune activation in a mosquito: Adults that emerge from infected larvae have stronger antibacterial activity in their hemocoel yet increased susceptibility to malaria infection(Ecology and Evolution, 2019-05) Brown, Lisa D.; Shapiro, Lillian L. M.; Thompson, Grayson A.; Estevez-Lao, Tania Y.; Hillyer, Julian F.Larval and adult mosquitoes mount immune responses against pathogens that invade their hemocoel. Although it has been suggested that a correlation exists between immune processes across insect life stages, the influence that an infection in the hemocoel of a larva has on the immune system of the eclosed adult remains unknown. Here, we used Anopheles gambiae to test whether a larval infection influences the adult response to a subsequent bacterial or malaria parasite infection. We found that for both female and male mosquitoes, a larval infection enhances the efficiency of bacterial clearance following a secondary infection in the hemocoel of adults. The adults that emerge from infected larvae have more hemocytes than adults that emerge from naive or injured larvae, and individual hemocytes have greater phagocytic activity. Furthermore, mRNA abundance of immune genes-such as cecropin A, Lysozyme C1, Stat-A, and Tep1-is higher in adults that emerge from infected larvae. A larval infection, however, does not have a meaningful effect on the probability that female adults will survive a systemic bacterial infection, and increases the susceptibility of females to Plasmodium yoelii, as measured by oocyst prevalence and intensity in the midgut. Finally, immune proficiency varies by sex; females exhibit increased bacterial killing, have twice as many hemocytes, and more highly express immune genes. Together, these results show that a larval hemocoelic infection induces transstadial immune activation-possibly via transstadial immune priming-but that it confers both costs and benefits to the emerged adults.