We determined genetic variance and gene flow across multiple scales (reaches, tributaries, and catchments) to examine the dispersal ability of the caddisfly, Neothremma alicia in streams along the Wasatch Range in the Rocky Mountains of Utah. Neothremma alicia is one of the most abundant caddisflies in this region. We generated DNA sequence data (mitochondrial COI) from 34 reaches, nested in 15 tributaries distributed across 3 adjacent catchments. We identified 47 haplotypes from a total of 486 individuals. The most abundant haplotype (H1) was found at all sites/reaches and comprised 44% of the total number of individuals sequenced. The remaining rare haplotypes (46) were recently derived from the dominant, H1 haplotype. All of the rare haplotypes were restricted to a single catchment with 81 % restricted to either a single tributary or to two adjacent tributaries. We found the largest FST values among tributaries and the smallest FST values between reaches within tributaries suggesting that dispersal and gene flow is largely confined to within tributaries. This result supports the observation that aerial adults commonly crawl and fly along the stream corridor, especially in deeply incised valleys of mountainous regions. Our analyses show that this population has experienced a bottleneck that may have reduced population genetic variance from many haplotypes to one single dominant haplotype, H1. The rare haplotypes may have diverged since the bottleneck from the H1 haplotype and thus, have not had time to disperse outside their catchment and in most cases outside their specific tributary. Our analyses indicated that the bottleneck took place between 1,000 and 10,000 years ago. Thus, it appears that most rare haplotypes have been unable to colonize outside of the tributary they originated in for around 1,000 years.

Four species of net-spinning caddisflies, Hydropsyche simulans Ross, Cheumatopsyche lasia Ross, Cheumatopsyche campyla Ross and Chimarra obscura (Walker) are common in the regulated portions of the Brazos River. Hydropsyche simulans spun capture nets with the largest meshdimensions; the two Cheumatopsyche species' nets had the next largest meshes, and Chimarra obscura spun nets with the smallest dimensions. Cheumatopsyche lasia and C. campyla constructed nets with similar sized meshes. The number of individuals m~2 and standing crop biomass were not significantly different among low, medium, and high velocities. Early hydropsychid instars fed on detritus while later instar H. simulans and C. campyla had larger proportions of animal material. Guts of later instar C. lasia individuals had a greater percentage of algae and diatoms.

abstract: An animal's ability to produce protein-based silk materials has evolved independently in many different arthropod lineages, satisfying various ecological necessities. However, regardless of their wide range of uses and their potential industrial and biomedical applications, advanced knowledge on the molecular structure of silk biopolymers is largely limited to those produced by spiders (order Araneae) and silkworms (order Lepidoptera). This thesis provides an in-depth molecular-level characterization of silk fibers produced by two vastly different insects: the caddisfly larvae (order Trichoptera) and the webspinner (order Embioptera). The molecular structure of caddisfly larval silk from the species <italic>Hesperophylax consimilis</italic> was characterized using solid-state nuclear magnetic resonance (ss-NMR) and Wide Angle X-ray Diffraction (WAXD) techniques. This insect, which typically dwells in freshwater riverbeds and streams, uses silk fibers as a strong and sticky nanoadhesive material to construct cocoons and cases out available debris. Conformation-sensitive <super>13</super>C chemical shifts and <super>31</super>P chemical shift anisotropy (CSA) information strongly support a unique protein motif in which phosphorylated serine- rich repeats (pSX)₄ complex with di- and trivalent cations to form rigid nanocrystalline &beta;-sheets. Additionally, it is illustrated through <super>31</super>P NMR and WAXD data that these nanocrystalline structures can be reversibly formed, and depend entirely on the presence of the stabilizing cations. Nanofiber silks produced by webspinners (order Embioptera) were also studied herein. This work addresses discrepancies in the literature regarding fiber diameters and tensile properties, revealing that the nanofibers are about 100 nm in diameter, and are stronger (around 500 MPa mean ultimate stress) than previous works suggested. Fourier-transform Infrared Spectroscopy (FT-IR), NMR and WAXD results find that approximately 70% of the highly repetitive glycine- and serine-rich protein core is composed of &beta;-sheet nanocrystalline structures. In addition, FT-IR and Gas-chromatography mass spectroscopy (GC-MS) data revealed a hydrophobic surface coating rich in long-chain lipids. The effect of this surface coating was studied with contact angle techniques; it is shown that the silk sheets are extremely hydrophobic, yet due to the microstructural and nanostructural details of the silk surface, are surprisingly adhesive to water. / Dissertation/Thesis / Doctoral Dissertation Biochemistry 2014

Some populations of newts (Taricha granulosa) possess large quantities of the neurotoxin tetrodotoxin (TTX) in their skin and eggs. Many populations of garter snake (Thamnophis sirtalis) are resistant to this toxin and can consume large numbers of newts with no negative effects. Despite the wealth of information acquired on the interaction between newts and their predator, garter snakes, very little research has been conducted on possible interactions between newts and other predators. I conducted a suite of experiments examining for the presence of other predators on newts, specifically focusing on predators of their eggs and larvae. I found a single predator, caddisfly larvae were capable of consuming the toxic eggs. Larval caddisflies are extremely abundant at one study site (775,000 caddisfly larvae per pond), and appear to be resistant to the negative effects of ingesting tetrodotoxin. After hatching, larval newts retain substantial quantities of TTX and most are unpalatable to predatory dragonfly naiads. Ovipositing female newts respond to the presence of caddisflies by depositing their eggs at the top of the water column where they are out of the reach of most predatory caddisflies. When caddisflies do consume a newt egg, some of the toxin is retained in their body tissues. Finally, caddisflies consume more newt eggs when those eggs contain less toxin versus eggs that contain large amounts of TTX. This may cause newt eggs that contain low quantities of TTX to more likely to die of predation which could ultimately drive an increase in toxicity of the adult population over time. Collectively, these findings indicate an additional player, caddisfly larvae, is a major predator of newts and could be involved in the evolution of tetrodotoxin toxicity in newts.

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