About

Patrick O'Grady is a Professor and Chair in the Department of Entomology at Cornell University. His role involves leading the department and contributing to the academic and research missions of the institution. The page does not specify his specific research focus, background, or key contributions, but as a faculty member within the Department of Entomology, his work is associated with the study of insects and their management.

Selected publications

• Review of Hawaiian Elmomyza species (Diptera, Drosophilidae, Scaptomyza). I. The cyrtandrae, exigua, and obscuricornis species groups, with the descriptions of nine new species

  The Catalogue of Life · 2026-02-16

  datasetOpen accessSenior author
  PublisherDOI

• The placement of Engiscaptomyza, Grimshawomyia, and Titanochaeta, three clades of endemic Hawaiian Drosophilidae (Diptera)

  The Catalogue of Life · 2026-02-16

  datasetOpen access1st authorCorresponding
  PublisherDOI

• Review of Hawaiian Elmomyza species (Diptera, Drosophilidae, Scaptomyza). I. The cyrtandrae, exigua, and obscuricornis species groups, with the descriptions of nine new species

  Open MIND · 2025-01-01

  datasetOpen accessSenior author

  This dataset contains the digitized treatments in Plazi based on the original journal article Rampasso, Augusto Santos, O’Grady, Patrick Michael (2025): Review of Hawaiian Elmomyza species (Diptera, Drosophilidae, Scaptomyza). I. The cyrtandrae, exigua, and obscuricornis species groups, with the descriptions of nine new species. Zootaxa 5729 (1): 1-42, DOI: 10.11646/zootaxa.5729.1.1, URL: https://doi.org/10.11646/zootaxa.5729.1.1AbstractThe subgenus Elmomyza, with 86 Hawaiian endemic species of the 274 described species of Scaptomyza, is the most diverse lineage in Scaptomyza. Here, we describe nine new species of Elmomyza (S. hiiakae, S. hinae, S. kamohoalii, S. kanaloai, S. kanei, S. kui, S. lonoi, S. mauii, S. peleae), bringing the total species in this subgenus to 95. We also redescribe S. exigua, including high-resolution images of the male terminalia, and update the published identification key. We expand the collection records for the Scaptomyza cyrtandrae species group and use morphology to erect two new species groups, the Scaptomyza exigua and obscuricornis species groups. Each of these groups is further divided into subgroups. In total, 28 (~30%) Elmomyza species are now placed into species groups. This is the first step into revising the subgenus Elmomyza, which still contains dozens of new species that are known, yet remain undescribed.

  OA PDFDOI

• The evolution of 2 male terminalia periphallic structures in <i>Drosophila</i> and related genera (Diptera: Drosophilidae)

  Insect Systematics and Diversity · 2025-07-01

  articleSenior author

  Abstract Insect terminalia are highly variable, especially in species with internal fertilization. The phallus, the primary intromittent copulatory organ, is often studied due to the extensive morphological variation in this structure contributing to reproductive isolation and subsequent species formation. However, non-intromittent components of the male terminalia, collectively referred to as periphallic sclerites, also play important roles in copulation and merit attention. The evolutionary patterns and processes leading to their differentiation remain poorly understood. This project analyzes the patterns of morphological variation of cercal modifications across the family Drosophilidae in a phylogenetic framework. We analyzed male terminalia of 121 species included in a 155 whole-genome sequence phylogeny representing 149 Drosophilidae species. We inferred the evolutionary history of 2 characters: the degree of cercal ventral modifications and the status of cercal spines. A broadened cercal ventral process lacking spines is the ancestral state in Drosophila and related genera and was the ancestral state of the 2 major subgenera, Sophophora and Drosophila. While cercal spines evolved early in the divergence of Sophophora and are widespread in this subgenus, this character developed multiple times in the subgenus Drosophila, mostly at terminal nodes. Our findings suggest a strong morphological constraint between the presence of cercal spines in cerci that have reduced ventral surface area. This constraint may be imposed by their role in the copulation process, further supporting sexual selection as the main driving force for the rapid male terminalia evolution.

  PublisherDOI

• Host plant nutrition drives fitness outcomes in the cactus specialist <i>Drosophila mettleri</i>

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-09-15

  preprintOpen accessSenior author

  Organisms must navigate complex interactions with host plants, microbial communities, and environmental cues to ensure their survival and reproductive success when adapting to novel environments. Due to their ecological constraints, host plant specialists can be used to study how these interactions affect fitness due to their ecological constraints. In specialist species, such as cactophilic Drosophila, it remains unclear how feeding behavior, substrate composition, and microbial interactions collectively shape fitness outcomes. We examined the effects of laboratory media (cornmeal vs. banana) differing in their base diet and cactus-derived additives (dried Saguaro powder, exudate from rotting Saguaro, soil soaked by rotting Saguaro) on fitness in Drosophila mettleri, a columnar cactus specialist that breeds in Saguaro cactus (Carnegiea gigantea) in the Sonoran Desert. Cactus supplements often reduced survival from egg to pupa, but increased survival from pupa to adult, resulting in stage specific tradeoffs shaping egg-to-adult fitness. Results show interactions between food substrate and cactus treatment: cactus supplementation reduced survival on banana media but increased survival on cornmeal-based diets. Feeding rate and overall amount of media consumed did not differ among treatments, indicating that differences in survival and fitness may depend on the broader nutritional environment and developmental stage. This suggests that studying host specialization should include multiple life stages.

  PublisherOA PDFDOI

• Single-fly genome assemblies fill major phylogenomic gaps across the Drosophilidae Tree of Life

  PLoS Biology · 2024-07-18 · 63 citations

  articleOpen accessCorresponding

  Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to assemble 101 drosophilid genomes from laboratory cultures, greatly increasing the number of genome assemblies for this taxonomic group. The next major challenge is to address the laboratory culture bias in taxon sampling by sequencing genomes of species that cannot easily be reared in the lab. Here, we build upon our previous methods to perform amplification-free ONT sequencing of single wild flies obtained either directly from the field or from ethanol-preserved specimens in museum collections, greatly improving the representation of lesser studied drosophilid taxa in whole-genome data. Using Illumina Novaseq X Plus and ONT P2 sequencers with R10.4.1 chemistry, we set a new benchmark for inexpensive hybrid genome assembly at US $150 per genome while assembling genomes from as little as 35 ng of genomic DNA from a single fly. We present 183 new genome assemblies for 179 species as a resource for drosophilid systematics, phylogenetics, and comparative genomics. Of these genomes, 62 are from pooled lab strains and 121 from single adult flies. Despite the sample limitations of working with small insects, most single-fly diploid assemblies are comparable in contiguity (>1 Mb contig N50), completeness (>98% complete dipteran BUSCOs), and accuracy (>QV40 genome-wide with ONT R10.4.1) to assemblies from inbred lines. We present a well-resolved multi-locus phylogeny for 360 drosophilid and 4 outgroup species encompassing all publicly available (as of August 2023) genomes for this group. Finally, we present a Progressive Cactus whole-genome, reference-free alignment built from a subset of 298 suitably high-quality drosophilid genomes. The new assemblies and alignment, along with updated laboratory protocols and computational pipelines, are released as an open resource and as a tool for studying evolution at the scale of an entire insect family.

  PublisherOA PDFDOI

• Genomics of a sexually selected sperm ornament and female preference in Drosophila

  Nature Ecology & Evolution · 2024-11-22 · 6 citations

  articleOpen access
  PublisherOA PDFDOI

• Genomics of a sexually selected sperm ornament and female preference in Drosophila

  Universität Zürich, ZORA · 2024-11-22

  articleOpen access
  PublisherDOI

• Single-fly assemblies fill major phylogenomic gaps across the Drosophilidae Tree of Life

  bioRxiv (Cold Spring Harbor Laboratory) · 2023-10-02 · 21 citations

  preprintOpen access

  Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to assemble 101 drosophilid genomes from laboratory cultures, greatly increasing the number of genome assemblies for this taxonomic group. The next major challenge is to address the laboratory culture bias in taxon sampling by sequencing genomes of species that cannot easily be reared in the lab. Here, we build upon our previous methods to perform amplification-free ONT sequencing of single wild flies obtained either directly from the field or from ethanol-preserved specimens in museum collections, greatly improving the representation of lesser studied drosophilid taxa in whole-genome data. Using Illumina Novaseq X Plus and ONT P2 sequencers with R10.4.1 chemistry, we set a new benchmark for inexpensive hybrid genome assembly at US $150 per genome while assembling genomes from as little as 35 ng of genomic DNA from a single fly. We present 183 new genome assemblies for 179 species as a resource for drosophilid systematics, phylogenetics, and comparative genomics. Of these genomes, 62 are from pooled lab strains and 121 from single adult flies. Despite the sample limitations of working with small insects, most single-fly diploid assemblies are comparable in contiguity (>1Mb contig N50), completeness (>98% complete dipteran BUSCOs), and accuracy (>QV40 genome-wide with ONT R10.4.1) to assemblies from inbred lines. We present a well-resolved multi-locus phylogeny for 360 drosophilid and 4 outgroup species encompassing all publicly available (as of August 2023) genomes for this group. Finally, we present a Progressive Cactus whole-genome, reference-free alignment built from a subset of 298 suitably high-quality drosophilid genomes. The new assemblies and alignment, along with updated laboratory protocols and computational pipelines, are released as an open resource and as a tool for studying evolution at the scale of an entire insect family.

  PublisherOA PDFDOI

• A New Species of Anticheta (Diptera: Sciomyzidae) from Mexico

  Zootaxa · 2023-05-22 · 1 citations

  articleOpen accessSenior author

  Anticheta patzcuaroensis Pote, new species (Diptera: Sciomyzidae), from Lake Pátzcuaro, Michoacán, Mexico, is described and illustrated. The most recent key to the genus Anticheta Haliday in the Nearctic region is edited to include the new species. Information is given about the Sciomyzidae holdings in the Cornell University Insect Collection.

  PublisherOA PDFDOI

Labs

• Entomology Department, Cornell UniversityPI