Biology subjects

Hamilton, C. A.

Publications and source records attributed to Hamilton, C. A..

8 recordsLinked to original sources

bioRxiv2023

The developmental gene disco regulates diel-niche evolution in adult moths

AbstractAnimals shift activity periods to reduce predation, minimize competition, or exploit new resources, and this can drive sensory system evolution. But adaptive mechanisms underlying niche- shifts are poorly understood, and model organisms are often too distantly related to reveal the genetic drivers. To address this, we examined expression patterns between two closely related silk moths that have undergone temporal niche divergence. We found 200-700 differentially expressed genes, including day upregulation in eye development and visual processing genes, and night upregulation of antennal and olfactory brain development genes. Further, clusters of circadian, sensory, and brain development genes co-expressed with diel-activity. In both species, eight genes showed expression significantly correlated to diel activity, and are involved in vision, olfaction, brain development, neural plasticity, energy utilization, and cellular maintenance. We repeatedly recovered disco, a zinc- finger transcription factor involved in antennal development, circadian activity, and optic lobe brain development in flies. While disco mutants have circadian arrhythmia, most studies attribute this to improper clock neuron development, not adult circadian maintenance. Comparing predicted 3D protein structure across moth and fly genetic models revealed disco likely retained developmental function with a conserved zinc finger domain, but gained functional zinc finger domains absent in D. melanogaster. These regions have several mutations between nocturnal and diurnal species that co- occur with higher levels of predicted phosphorylation sites. With robust circadian expression, functional nocturnal and diurnal mutations, and structural and sequence conservation, we hypothesize that disco may be a master regulator contributing to diel-activity diversification in adult moths. SignificanceInsect diel-activity patterns are diverse, yet the underlying evolutionary processes are poorly understood. Light environment powerfully entrains circadian rhythms and drives diel-niche and sensory evolution. To investigate its impact, we compared gene expression in closely related day- and night-active wild silk moths, with otherwise similar ecologies. Expression patterns that varied with diel activity included genes linked to eye development, neural plasticity and cellular maintenance. Notably, disco, which encodes a zinc-finger transcription factor involved in pupal Drosophila optic lobe and antennal development, shows robust adult circadian mRNA cycling in moth heads, is highly conserved in moths, and has additional zinc-finger domains with specific nocturnal and diurnal mutations. We hypothesize that disco may contribute to diversification of adult diel-activity patterns in moths.

evolutionary biology↗

bioRxiv2021

Adaptive shifts underlie the divergence in wing morphology in bombycoid moths

The evolution of flapping flight is linked to the prolific success of insects. Across Insecta, wing morphology diversified, strongly impacting aerodynamic performance. In the presence of ecological opportunity, discrete adaptive shifts and early bursts are two processes hypothesized to give rise to exceptional morphological diversification. Here, we use the sister-families Sphingidae and Saturniidae to answer how the evolution of aerodynamically important traits is linked to clade divergence and through what process(es) these traits evolve. Many agile Sphingidae evolved hover-feeding behaviors, while adult Saturniidae lack functional mouth parts and rely on a fixed energy budget as adults. We find that Sphingidae underwent an adaptive shift in wing morphology coincident with life history and behavior divergence, evolving small high aspect-ratio wings advantageous for power reduction that can be moved at high frequencies, beneficial for flight control. In contrast, Saturniidae, which do not feed as adults, evolved large wings and morphology which surprisingly does not reduce aerodynamic power, but could contribute to their erratic flight behavior, aiding in predator avoidance. We suggest that after the evolution of flapping flight, diversification of wing morphology can be potentiated by adaptative shifts, shaping the diversity of wing morphology across insects.

evolutionary biology↗

bioRxiv2020

Wing shape evolution in bombycoid moths reveals two distinct strategies for maneuverable flight

Across insects, wing shape and size have undergone dramatic divergence even in closely related sister groups, but we do not yet know morphology changes in tandem with kinematics to support body weight within available aerodynamic power and how the specific force production patterns are linked to changes in behavior. Hawkmoths and wild silkmoths are two such diverse sister families with divergent wing morphology. Using 3d kinematics and quasi-steady aerodynamic modeling, we compare the aerodynamics and the contributions of wing shape, size, and kinematics in 10 moth species. We find that wing movement also diverges between the clades and underlies two distinct strategies for flight. Hawkmoths use wing kinematics, especially high frequencies, to enhance force, but wing morphologies that reduces power. Silkmoths use wing morphology to enhance force, and high amplitude wingstrokes to reduce power. Both strategies converge on similar aerodynamic power and can support similar body mass ranges, but their within-wingstroke force profiles are quite different and linked to the hovering flight of hawkmoths and the bobbing flight of silkmoths. These two groups of moths each fly more like other, distantly related insects than they do each other, demonstrating the convergence and diversity of flapping flight evolution.

physiology↗

bioRxiv2020

Evolution of body size and wing shape trade-offs in arsenurine silkmoths

AO_SCPLOWBSTRACTC_SCPLOWOne of the key objectives in biological research is understanding how evolutionary processes have produced Earths biodiversity. These processes have led to a vast diversity of wing shapes in insects; an unanswered question especially pronounced in moths. As one of the major predators of nocturnal moths, bats are thought to have been involved in a long evolutionary arms race with their prey. In response, moths are thought to have evolved many counter strategies, such as diverse wing shapes and large body sizes. However, the tradeoffs between body size and wing shape are not well understood. Here we examined the evolution of wing shape in the wild silkmoth subfamily Arsenurinae (Saturniidae). By using phylogenomics and geometric morphometrics, we established the framework to evaluate potential evolutionary relationships between body size and wing shape. The phylogeny was inferred based on 781 loci from target capture data of 42 arsenurine species representing all 10 recognized genera. We found there are evolutionary trade-offs between body size, wing shape, and the interaction of fore- and hindwing shape. Namely, body size decreases with increasing hindwing length, but increases as forewing shape becomes more complex. Additionally, hindwing shape has a significant effect on forewing shape complexity. The complex wing shapes that make Arsenurinae, and silkmoths as a whole, so charismatic are likely driven by the strong forces of natural selection and genomic constraints. One other important outcome was discovering within our data one of the most vexing problems in phylogenetic inference - a region of a tree that possesses short branches and no "support" for relationships (i.e., a polytomy). These parts of the Tree of Life are often some of the most interesting from an evolutionary standpoint. To investigate this problem, we used reciprocal illumination to determine the most probable generic relationships within the Arsenurinae by inspecting differing phylogenetic inferences, alternative support values, quartets, and phylogenetic networks to reveal hidden phylogenetic signal.

evolutionary biology↗

bioRxiv2019

Hematological and Neurological Expressed 1 (HN1): a predictive and pharmacodynamic biomarker of metformin response in endometrial cancers.

Preoperative use of metformin in obese women with endometrioid endometrial cancer (EEC) reduces tumor proliferation and inhibits the mammalian target of rapamycin (mTOR) pathway, though is only effective in select cases. This study sought to identify a predictive and/or pharmacodynamic proteomic signature of metformin response to tailor its pharmacologic use. Matched pre- and post-metformin treated tumor tissues from a recently completed phase 0 window trial of metformin in EEC patients (ClinicalTrials.gov: NCT01911247), were analyzed by mass spectrometry (MS)-based proteomic and immunohistochemical analyses. Hematological and neurological expressed 1 (HN1) was significantly elevated in metformin responders (n=13) versus non-responders (n=7), which was also found to decrease in abundance in metformin responders following treatment; observations that were verified by immunohistochemical staining for HN1. Metformin response and loss of HN1 was assessed in RL95-2 and ACI-181 endometrial cancer cell lines. We further identified that silencing of HN1 abundance does not alter cellular response to metformin or basal cell proliferation, but that HN1 abundance does decrease in response to metformin treatment in RL95-2 and ACI-181 endometrial cancer cell lines. These data suggest that HN1 represents a predictive and pharmacodynamic biomarker of metformin response that, if validated in larger patient populations, may enable pre-operative EEC patient stratification to metformin treatment and the ability to monitor patient response.\n\nNovelty and ImpactHematological and Neurological Expressed 1 (HN1) is elevated in endometrioid endometrial cancer (EEC) patients that respond to metformin vs non-responders and decreases after treatment. HN1 decreases after metformin treatment of EEC cells in vitro, but is not necessary for metformin response or proliferation. We report HN1 as a novel predictive and pharmacodynamic biomarker of metformin response in EEC that may enable pre-operative EEC patient stratification to metformin treatment and the ability to monitor patient response.

cancer biology↗

bioRxiv2019

Phylogenetic systematics and evolution of the spider infraorder Mygalomorphae using genomic scale data

AO_SCPLOWBSTRACTC_SCPLOWThe Infraorder Mygalomorphae is one of the three main lineages of spiders comprising over 3,000 nominal species. This ancient group has a world-wide distribution that includes among its ranks large and charismatic taxa such as tarantulas, trapdoor spiders, and highly venomous funnel web spiders. Based on past molecular studies using Sanger-sequencing approaches, numerous mygalomorph families (e.g., Hexathelidae, Ctenizidae, Cyrtaucheniidae, Dipluridae and Nemesiidae) have been identified as non-monophyletic. However, these data were unable to sufficiently resolve the higher-level (intra- and interfamilial) relationships such that the necessary changes in classification could be made with confidence. Here we present the most comprehensive phylogenomic treatment of the spider infraorder Mygalomorphae conducted to date. We employ 472 loci obtained through Anchored Hybrid Enrichment to reconstruct relationships among all the mygalomorph spider families and estimate the timeframe of their diversification. We performed an extensive generic sampling of all currently recognized families, which has allowed us to assess their status, and as a result, propose a new classification scheme. Our generic-level sampling has also provided an evolutionary framework for revisiting questions regarding silk use in mygalomorph spiders. The first such analysis for the group within a strict phylogenetic framework shows that a sheet web is likely the plesiomorphic condition for mygalomorphs, as well as providing hints to the ancestral foraging behavior for all spiders. Our divergence time estimates, concomitant with detailed biogeographic analysis, suggest that both ancient continental-level vicariance and more recent dispersal events have played an important role in shaping modern day distributional patterns. Based on our results, we relimit the generic composition of the Ctenizidae, Cyrtaucheniidae, Dipluridae and Nemesiidae. We also elevate five subfamilies to family rank: Anamidae (NEW RANK), Euagridae (NEW RANK), Ischnothelidae (NEW RANK), Pycnothelidae (NEW RANK), and Bemmeridae (NEW RANK). The three families Hermachidae (NEW FAMILY), Microhexuridae (NEW FAMILY), and Stasimopidae (NEW FAMILY) are newly proposed. Such a major rearrangement in classification, recognizing eight newly established family-level rank taxa, is the largest the group has seen in over three decades since Ravens (1985) taxonomic treatment.

evolutionary biology↗

bioRxiv2019

Phylogenomics reveals major diversification rate shifts in the evolution of silk moths and relatives

The silkmoths and their relatives (Bombycoidea) are an ecologically and taxonomically diverse superfamily that includes some of the most charismatic species of all the Lepidoptera. Despite displaying some of the most spectacular forms and ecological traits among insects, relatively little attention has been given to understanding their evolution and the drivers of their diversity. We heavily sampled (both in taxa and loci) all major lineages of the Bombycoidea, producing a well-supported phylogeny that identified important evolutionary patterns (e.g., morphology, biogeography, and differences in speciation and extinction). Importantly, analysis of diversification rates highlights the stark increases that exist within the Sphingidae (hawkmoths) and Saturniidae (wild silkmoths). We postulate that these rate shifts are due to differences in the intense selective pressures from insectivorous bats. The study also introduces a new Bombycoidea-specific Anchored Hybrid Enrichment (AHE) probe set, a modified DNA extraction protocol for Lepidoptera specimens from natural history collections, and additional information on the existing AHE bioinformatics pipeline. Our research highlights the flexibility of AHE to generate genomic data from a wide range of museum specimens, both age and preservation method, and will allow researchers to tap into the wealth of biological data residing in natural history collections around the globe.

evolutionary biology↗

bioRxiv2018

Golden Orbweavers Ignore Biological Rules: Phylogenomic and Comparative Analyses Unravel a Complex Evolution of Sexual Size Dimorphism

Instances of sexual size dimorphism (SSD) provide the context for rigorous tests of biological rules of size evolution, such as Copes Rule (phyletic size increase), Renschs Rule (allometric patterns of male and female size), as well as male and female body size optima. In certain spider groups, such as the golden orbweavers (Nephilidae), extreme female-biased SSD (eSSD, female:male body length [≥] 2) is the norm. Nephilid genera construct webs of exaggerated proportions which can be aerial, arboricolous, or intermediate (hybrid). First, we established the backbone phylogeny of Nephilidae using 367 Anchored Hybrid Enrichment (AHE) markers, then combined these data with classical markers for a reference species-level phylogeny. Second, we used the phylogeny to test Cope and Renschs Rules, sex specific size optima, and the coevolution of web size, type, and features with female and male body size and their ratio, SSD. Male, but not female, size increases significantly over time, and refutes Copes Rule. Allometric analyses reject the converse, Renschs Rule. Male and female body sizes are uncorrelated. Female size evolution is random, but males evolve towards an optimum size (3.2-4.9 mm). Overall, female body size correlates positively with absolute web size. However, intermediate sized females build the largest webs (of the hybrid type), giant female Nephila and Trichonephila build smaller webs (of the aerial type), and the smallest females build the smallest webs (of the arboricolous type). We propose taxonomic changes based on the criteria of clade age, monophyly and exclusivity, classification information content, diagnosability, and arachnological community practice. We resurrect the family Nephilidae Simon 1894 that contains Clitaetra Simon 1889, the Cretaceous Geratonephila Poinar & Buckley 2012, Herennia Thorell 1877, Indoetra Kuntner 2006, new rank, Nephila Leach 1815, Nephilengys L. Koch 1872, Nephilingis Kuntner 2013, and Trichonephila Dahl 1911, new rank. We propose the new clade Orbipurae to contain Araneidae Clerck 1757, Phonognathidae Simon 1894, new rank, and Nephilidae. Nephilid female gigantism is a phylogenetically-ancient phenotype (over 100 ma), as is eSSD, though their magnitudes vary by lineage and, to some extent, biogeographically.

evolutionary biology↗