Contributions of Henry Weed Fowler (1878-1965), with a brief early history of ichthyology at the Academy of Natural Sciences of Philadelphia
Abstract not supplied at this time
Proceedings of the Academy of Natural Sciences of ↗
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Browsing the literature
For this edition of Browsing the Literature, we have two new papers from Rangeland Ecology & Management, a series of basic ecology papers with an international scope from journals such as the Proceedings of the National Academy of Sciences (USA), Science, and Nature, and several papers advancing our understanding of drought and carbon at global scales. Additionally, several papers on sagebrush-steppe rangelands are covered with transferable insights to other rangeland types.
Rangelands↗
Capturing patterns of evolutionary relatedness with reflectance spectra to model and monitor biodiversity
Biogeographic history can set initial conditions for vegetation community assemblages that determine their climate responses at broad extents that land surface models attempt to forecast. Numerous studies have indicated that evolutionarily conserved biochemical, structural, and other functional attributes of plant species are captured in visible-to-short wavelength infrared, 400 to 2,500 nm, reflectance properties of vegetation. Here, we present a remotely sensed phylogenetic clustering and an evolutionary framework to accommodate spectra, distributions, and traits. Spectral properties evolutionarily conserved in plants provide the opportunity to spatially aggregate species into lineages (interpreted as “lineage functional types” or LFT) with improved classification accuracy. In this study, we use Airborne Visible/Infrared Imaging Spectrometer data from the 2013 Hyperspectral Infrared Imager campaign over the southern Sierra Nevada, California flight box, to investigate the potential for incorporating evolutionary thinking into landcover classification. We link the airborne hyperspectral data with vegetation plot data from 1372 surveys and a phylogeny representing 1,572 species. Despite temporal and spatial differences in our training data, we classified plant lineages with moderate reliability (Kappa = 0.76) and overall classification accuracy of 80.9%. We present an assessment of classification error and detail study limitations to facilitate future LFT development. This work demonstrates that lineage-based methods may be a promising way to leverage the new-generation high-resolution and high return-interval hyperspectral data planned for the forthcoming satellite missions with sparsely sampled existing ground-based ecological data.
Proceedings of the Natural Academy of Sciences↗
Species within the Genus Encyonema Kützing, Including Two New Species Encyonema reimeri sp. nov. and E. nicafei sp. nov. and E. stoermeri nom. nov., stat. nov.
We observed six diatom taxa from North American samples and one taxon from China that are considered within the genus Encyonema Kützing. Two of the taxa are described as new, Encyonema reimeri Spaulding, Pool et Castro sp. nov . and Encyonema nicafei Spaulding sp. nov . A third taxon, Encyonema stoermeri Spaulding, Pool et Castro nom. nov., shat. nov . is assigned a new name and rank. In the past, these taxa have been ascribed to several names, but primarily the names Cymbella muelleri Hustedt and C. muelleri f. ventricosa (Tempère et Peragallo) Reimer have been used, based on their inclusion in the two volumes of “The Diatoms of the United States”. We compare the new species with other members of this group of taxa, including Encyonema latum Krammer, E. sinicum Krammer and E. yellowstonianum Krammer. This group of species shares the features of 1) a broad axial area, 2) raphe branches curved with the convex side toward the dorsal valve margin, 3) slightly expanded and dorsally deflected proximal raphe ends, and 4) oval areolae near the axial area, becoming lineolate, or transapically elongate, towards the dorsal margin. We expect that many of the species reported in the U.S. have been identified using names of species from other continents. We also expect that critical microscopy and use of original literature is likely to clarify the geographic distribution of species within Encyonema . This work is important in order to understand, document and protect the species diversity of diatoms and their aquatic habitats.
Proceedings of the Academy of Natural Sciences of ↗
Species within the genus Encyonema Kützing, including two new species Encyonema reimeri sp. nov. and E. nickcafei sp. nov. and E. stoermeri nom. nov., stat. nov
No abstract available.
Proceedings of the Academy of Natural Sciences of ↗
Additions to the ichthyofauna of the Bahama Islands, with comments on endemic species
Literature records or other documentation are given for 57 species of shorefishes added to the Bahaman ichthyofauna since publication of Fishes of the Bahamas ; included are 32 new species described or discovered since 1967. Known distribution is specified for each species, including extralimital ranges of non-endemics. Fourteen species are listed as known only from the Bahamas although some likely occur elsewhere. It is concluded that the Bahamas has played a minor role in the evolution of Atlantic tropical marine fishes. [Bahaman ichthyofauna, endemism, new records]
Proceedings of the Academy of Natural Sciences of ↗
Repeating caldera collapse events constrain fault friction at the kilometer scale
Fault friction is central to understanding earthquakes, yet laboratory rock mechanics experiments are restricted to, at most, meter scale. Questions thus remain as to the applicability of measured frictional properties to faulting in situ. In particular, the slip-weakening distance d c "> d c dc strongly influences precursory slip during earthquake nucleation, but scales with fault roughness and is challenging to extrapolate to nature. The 2018 eruption of K̄ılauea volcano, Hawaii, caused 62 repeatable collapse events in which the summit caldera dropped several meters, accompanied by M W "> M W MW 4.7 to 5.4 very long period (VLP) earthquakes. Collapses were exceptionally well recorded by global positioning system (GPS) and tilt instruments and represent unique natural kilometer-scale friction experiments. We model a piston collapsing into a magma reservoir. Pressure at the piston base and shear stress on its margin, governed by rate and state friction, balance its weight. Downward motion of the piston compresses the underlying magma, driving flow to the eruption. Monte Carlo estimation of unknowns validates laboratory friction parameters at the kilometer scale, including the magnitude of steady-state velocity weakening. The absence of accelerating precollapse deformation constrains d c "> d c dc to be ≤ 10 "> ≤ 10 ≤10 mm, potentially much less. These results support the use of laboratory friction laws and parameters for modeling earthquakes. We identify initial conditions and material and magma-system parameters that lead to episodic caldera collapse, revealing that small differences in eruptive vent elevation can lead to major differences in eruption volume and duration. Most historical basaltic caldera collapses were, at least partly, episodic, implying that the conditions for stick–slip derived here are commonly met in nature.
Hawaii↗
Aquatic insect ecophysiological traits reveal phylogenetically based differences in dissolved cadmium susceptibility
We used a phylogenetically based comparative approach to evaluate the potential for physiological studies to reveal patterns of diversity in traits related to susceptibility to an environmental stressor, the trace metal cadmium (Cd). Physiological traits related to Cd bioaccumulation, compartmentalization, and ultimately susceptibility were measured in 21 aquatic insect species representing the orders Ephemeroptera, Plecoptera, and Trichoptera. We mapped these experimentally derived physiological traits onto a phylogeny and quantified the tendency for related species to be similar (phylogenetic signal). All traits related to Cd bioaccumulation and susceptibility exhibited statistically significant phylogenetic signal, although the signal strength varied among traits. Conventional and phylogenetically based regression models were compared, revealing great variability within orders but consistent, strong differences among insect families. Uptake and elimination rate constants were positively correlated among species, but only when effects of body size and phylogeny were incorporated in the analysis. Together, uptake and elimination rates predicted dramatic Cd bioaccumulation differences among species that agreed with field-based measurements. We discovered a potential tradeoff between the ability to eliminate Cd and the ability to detoxify it across species, particularly mayflies. The best-fit regression models were driven by phylogenetic parameters (especially differences among families) rather than functional traits, suggesting that it may eventually be possible to predict a taxon's physiological performance based on its phylogenetic position, provided adequate physiological information is available for close relatives. There appears to be great potential for evolutionary physiological approaches to augment our understanding of insect responses to environmental stressors in nature. ?? 2008 by The National Academy of Sciences of the USA.
Proceedings of the National Academy of Sciences of↗
Contribution of climate-driven change in continental water storage to recent sea-level rise
Using a global model of continental water balance, forced by interannual variations in precipitation and near-surface atmospheric temperature for the period 1981-1998, we estimate the sea-level changes associated with climate-driven changes in storage of water as snowpack, soil water, and ground water; storage in ice sheets and large lakes is not considered. The 1981-1998 trend is estimated to be 0.12 mm/yr, and substantial interannual fluctuations are inferred; for 1993-1998, the trend is 0.25 mm/yr. At the decadal time scale, the terrestrial contribution to eustatic (i.e., induced by mass exchange) sea-level rise is significantly smaller than the estimated steric (i.e., induced by density changes) trend for the same period, but is not negligibly small. In the model the sea-level rise is driven mainly by a downtrend in continental precipitation during the study period, which we believe was generated by natural variability in the climate system.
Proceedings of the National Academy of Sciences of↗
An introduced and a native vertebrate hybridize to form a genetic bridge to a second native species
The genetic impacts of hybridization between native and introduced species are of considerable conservation concern, while the possibility of reticulate evolution affects our basic understanding of how species arise and shapes how we use genetic data to understand evolutionary diversification. By using mitochondrial NADH dehydrogenase subunit 2 (ND2) sequences and 467 amplified fragment-length polymorphism nuclear DNA markers, we show that the introduced white sucker (Catostomus commersoni) has hybridized with two species native to the Colorado River Basin - the flannelmouth sucker (Catostomus latipinnis) and the bluehead sucker (Catostomus discobolus). Hybrids between the flannelmouth sucker and white sucker have facilitated introgression between the two native species, previously isolated by reproductive barriers, such that individuals exist with contributions from all three genomes. Most hybrids had the mitochondrial haplotype of the introduced white sucker, emphasizing its pivotal role in this three-way hybridization. Our findings highlight how introduced species can threaten the genetic integrity of not only one species but also multiple previously reproductively isolated species. Furthermore, this complex three-way reticulate (as opposed to strictly bifurcating) evolution suggests that seeking examples in other vertebrate systems might be productive. Although the present study involved an introduced species, similar patterns of hybridization could result from natural processes, including stream capture or geological formations (e.g., the Bering land bridge). ?? 2008 by The National Academy of Sciences of the USA.
Proceedings of the National Academy of Sciences of↗
Fluctuating survival selection explains variation in avian group size
Most animal groups vary extensively in size. Because individuals in certain sizes of groups often have higher apparent fitness than those in other groups, why wide group size variation persists in most populations remains unexplained. We used a 30-y mark–recapture study of colonially breeding cliff swallows ( Petrochelidon pyrrhonota ) to show that the survival advantages of different colony sizes fluctuated among years. Colony size was under both stabilizing and directional selection in different years, and reversals in the sign of directional selection regularly occurred. Directional selection was predicted in part by drought conditions: birds in larger colonies tended to be favored in cooler and wetter years, and birds in smaller colonies in hotter and drier years. Oscillating selection on colony size likely reflected annual differences in food availability and the consequent importance of information transfer, and/or the level of ectoparasitism, with the net benefit of sociality varying under these different conditions. Averaged across years, there was no net directional change in selection on colony size. The wide range in cliff swallow group size is probably maintained by fluctuating survival selection and represents the first case, to our knowledge, in which fitness advantages of different group sizes regularly oscillate over time in a natural vertebrate population.
Proceedings of the National Academy of Sciences of↗
Weak support for disappearance and restricted emergence/persistence of highly pathogenic influenza A in North American waterfowl
Krauss et al. (1) use lack of detection of highly pathogenic (HP) H5 clade 2.3.4.4 (henceforth "H5") influenza A viruses (IAVs) from >22,000 wild bird samples collected in North America in 2014–2015 to argue that HP H5 IAVs disappeared from waterfowl and that unresolved mechanisms restrict emergence and perpetuation of HP IAVs in natural reservoir species. Here we offer an alternative interpretation.
Proceedings of the National Academy of Sciences↗
Fire, climate and changing forests
A changing climate implies potential transformations in plant demography, communities, and disturbances such as wildfire and insect outbreaks. How do these dynamics play out in terrestrial ecosystems across scales of space and time? “Vegetation type conversion” (VTC) is a term used to describe abrupt and long-lasting changes in vegetation structure and composition due to various kinds of perturbations. For example, it has long been observed that fire-adapted ecosystems such as the California chaparral shrublands are readily replaced by non-native annual grasses when humans increase fire frequency. Similar effects are being observed in Sonoran Desert plant communities, where invasion by non-native buffelgrass (Cenchrus ciliare) exposes a fire-sensitive plant community to high-intensity fires, which are lethal to the long-lived iconic Sonoran flora such as Saguaro cactus (Carnegiea gigantea). While type conversions following severe disturbance have been observed for some time, the mechanisms that underlay such changes are only recently coming to light. Threshold behavior is of particular concern: as various climate indices pass critical values, some ecosystems may be reaching points of no return where recovery to the earlier state is no longer possible. A recent publication in the Proceedings of the National Academy of Sciences, U.S., has now revealed that increased fire severity impairs post-fire forest regeneration, setting the stage for potential large-scale type conversion of western conifer forests.
Nature Plants↗
Observational changes to the natural flow regime in Lee Creek in relation to altered precipitation patterns and its implication for fishes
The natural flow regime is important for structuring streams and their resident ichthyofauna and alterations to this regime can have cascading consequences. We sought to determine if changes in hydrology could be attributed to changes in precipitation in a minimally altered watershed (Lee Creek). The stream flow regime was analyzed using Indicators of Hydrologic Alteration (IHA) software, and data from a nearby climate station were used to summarize concurrent precipitation patterns. We discovered that Lee Creek hydrology had become flashier (i.e., increased frequency of extreme events of shorter duration) since 1992 coincident with changes in precipitation patterns. Specifically, our results show fewer but more intense rain events within the Lee Creek watershed. Our research provides evidence that climate-induced changes to the natural flow regime are currently underway and additional research on its effects on the fish community is warranted.
Arkansas, Oklahoma↗
A pheromone antagonist liberates female sea lamprey from a sensory trap to enable reliable communication
The evolution of male signals and female preferences remains a central question in the study of animal communication. The sensory trap model suggests males evolve signals that mimic cues used in nonsexual contexts and thus manipulate female behavior to generate mating opportunities. Much evidence supports the sensory trap model, but how females glean reliable information from both mimetic signals and their model cues remains unknown. We discovered a mechanism whereby a manipulative male signal guides reliable communication in sea lamprey ( Petromyzon marinus ). Migratory sea lamprey follow a larval cue into spawning streams; once sexually mature, males release a pheromone that mimics the larval cue and attracts females. Females conceivably benefit from the mimetic pheromone during mate search but must discriminate against the model cue to avoid orienting toward larvae in nearby nursery habitats. We tested the hypothesis that spawning females respond to petromyzonol sulfate (PZS) as a behavioral antagonist to avoid attraction to the larval cue while tracking the male pheromone despite each containing attractive 3-keto petromyzonol sulfate (3kPZS). We found 1) PZS inhibited electrophysiological responses to 3kPZS and abated preferences for 3kPZS when mixed at the same or greater concentrations, 2) larvae released more PZS than 3kPZS whereas males released more 3kPZS than PZS, and 3) mixtures of 3kPZS and PZS applied at ratios measured in larval and male odorants resulted in the discrimination observed between the natural odors. Our study elucidates how communication systems that arise via deception can facilitate reliable communication.
Proceedings of the National Academy of Sciences of↗
Ecological potential of the Grand Calumet River basin
The Grand Calumet River and watershed have been severely degraded by industrialization and urbanization, and yet several high-quality natural areas remain intact. The degraded condition presents numerous opportunities for pollution mitigation and ecosystem restoration. In many areas of the river and watershed, biological communities are characterized by low diversity and pollution-tolerant organisms. By establishing programs of nonnative species control, prescribed burning, sediment removal, wetland establishment and extirpated species re-introduction, the Grand Calumet can be improved to reflect some of its natural history. The dredging plan for the river presents an opportunity to coordinate simultaneous improvement and restoration plans. Possibilities for each section of the river are discussed.
Proceedings of the Indiana Academy of Science↗
History and environmental setting of the Grand Calumet River
The Grand Calumet River lies in an area of great ecological diversity, a result of the convergence of three biomes during glaciation. Over thousands of years the region and the river have changed ecologically due to ice retreat, lake level declines, settlement and industrialization. Settlement and industrialization have greatly accelerated the rate of change, and the Grand Calumet River and its basin are now subject to the added effects of years of direct pollution. For years, industries directly discharged into the waterway; and those contaminants remain locked in the sediment a century later. In order to preserve the remaining surrounding natural areas and to improve the Grand Calumet River, buried contaminants would have to be dredged from the river. Restoration needs to be implemented as part of the clean-up process, and recontamination should be prevented.
Proceedings of the Indiana Academy of Science↗
Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen
Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton ( Holopedium , Daphnia, and Leptodiaptomus ) are comprised of ≈20–40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13 C content of these lakes to augment the small, natural contrast in 13 C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread.
Wisconsin↗