Caecilia volcani

Number of Pages: 2Integrative BiologyGeological Science

Agassiz, Garman, Albatross, and the Collection of Deep-sea Fishes

The first of Alexander Agassiz’ voyages on the U.S. Fish Commission steamer Albatross in 1891 yielded significant scientific results. This paper reviews the background of the voyage, including the career path that led Agassiz to the back deck of the Albatross. We also give a brief account of the life and work of Samuel Garman. Garman wrote up the ichthyological material from this Albatross voyage in a magnificent book on deep-sea fishes published in 1899. This book was exceptional in its coverage, anatomical detail, and recognition of phylogenetically important morphology

An Empirical Test Indicates Only Qualitatively Honest Aposematic Signaling Within a Population of Vertebrates

Signaling is an important part of intraspecific and interspecific interactions. Theoretical work examining honest signaling in aposematic species (e.g., those with conspicuous colors and secondary defenses) has focused primarily on discerning the patterns between conspicuousness and defense within populations. Most empirical work, however, has investigated these patterns across populations or species. Here, we test for honest signaling across individuals within a population of the aposematic poison frog, Ranitomeya imitator. We find no evidence that increasing levels of the aposematic signal are correlated with increasing levels of defense in this species, indicating that our study population does not signal in a quantitatively honest manner, but rather that the signal is qualitatively honest. Additionally, we found no evidence that frogs with higher levels of defense behave more boldly as a result of the presumed increased ecological release from predation, an expected outcome in a qualitatively honest system. We discuss our findings in light of the ecology and evolution of R. imitator, and suggest mechanisms that may explain the absence of a relationship between toxicity and the aposematic signal

Some Items to Consider Before You Change the Calving Season of Your Beef Cow Herd

This publication gives important items to consider before changing calving seasons of beef cow herds

Bone Density Variation in Rattails (Macrouridae,Gadiformes): Buoyancy, Depth, Body Size, and Feeding

A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Extreme abiotic factors in deep-sea environments, such as near-freezing temperatures, low light, and high hydrostatic pressure, drive the evolution of adaptations that allow organisms to survive under these conditions. Pelagic and benthopelagic fishes that have invaded the deep sea face physiological challenges from increased compression of gasses at depth, which limits the use of gas cavities as a buoyancy aid. One adaptation observed in deep-sea fishes to increase buoyancy is a decrease of high-density tissues. In this study, we analyze mineralization of high-density skeletal tissue in rattails (family Macrouridae), a group of widespread benthopelagic fishes that occur from surface waters to greater than 7000 m depth. We test the hypothesis that rattail species decrease bone density with increasing habitat depth as an adaptation to maintaining buoyancy while living under high hydrostatic pressures. We performed micro-computed tomography (micro-CT) scans on 15 species and 20 specimens of rattails and included two standards of known hydroxyapatite concentration (phantoms) to approximate voxel brightness to bone density. Bone density was compared across four bones (eleventh vertebra, lower jaw, pelvic girdle, and first dorsal-fin pterygiophore). On average, the lower jaw was significantly denser than the other bones. We found no correlation between bone density and depth or between bone density and phylogenetic relationships. Instead, we observed that bone density increases with increasing specimen length within and between species. This study adds to the growing body of work that suggests bone density can increase with growth in fishes, and that bone density does not vary in a straightforward way with depth

Using Pareto Fronts to Evaluate Polyp Detection Algorithms for CT Colonography

We evaluate and improve an existing curvature-based region growing algorithm for colonic polyp detection for our CT colonography (CTC) computer-aided detection (CAD) system by using Pareto fronts. The performance of a polyp detection algorithm involves two conflicting objectives, minimizing both false negative (FN) and false positive (FP) detection rates. This problem does not produce a single optimal solution but a set of solutions known as a Pareto front. Any solution in a Pareto front can only outperform other solutions in one of the two competing objectives. Using evolutionary algorithms to find the Pareto fronts for multi-objective optimization problems has been common practice for years. However, they are rarely investigated in any CTC CAD system because the computation cost is inherently expensive. To circumvent this problem, we have developed a parallel program implemented on a Linux cluster environment. A data set of 56 CTC colon surfaces with 87 proven positive detections of polyps sized 4 to 60 mm is used to evaluate an existing one-step, and derive a new two-step region growing algorithm. We use a popular algorithm, the Strength Pareto Evolutionary Algorithm (SPEA2), to find the Pareto fronts. The performance differences are evaluated using a statistical approach. The new algorithm outperforms the old one in 81.6% of the sampled Pareto fronts from 20 simulations. When operated at a suitable sensitivity level such as 90.8% (79/87) or 88.5% (77/87), the FP rate is decreased by 24.4% or 45.8% respectively

Alkaloid defenses of co-mimics in a putative Müllerian mimetic radiation

Background Polytypism in aposematic species is unlikely according to theory, but commonly seen in nature. Ranitomeya imitator is a poison frog species exhibiting polytypic mimicry of three congeneric model species (R. fantastica, R. summersi, and two morphs of R. variabilis) across four allopatric populations (a "mimetic radiation"). In order to investigate chemical defenses in this system, a key prediction of Müllerian mimicry, we analyzed the alkaloids of both models and mimics from four allopatric populations. Results In this study we demonstrate distinct differences in alkaloid profiles between co-mimetic species within allopatric populations. We further demonstrate that R. imitator has a greater number of distinct alkaloid types than the model species and more total alkaloids in all but one population. Conclusions Given that R. imitator is the more abundant species in these populations, R. imitator is likely driving the majority of predator-learned avoidance in these complexes. The success of Ranitomeya imitator as a putative advergent mimic may be a direct result of differences in alkaloid sequestration. Furthermore, we propose that automimicry within co-mimetic species is an important avenue of research