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Articles 91 - 120 of 342
Full-Text Articles in Ecology and Evolutionary Biology
Relating Predator Community Ecology And Duck Nest Survival In Eastern South Dakota, Samantha R. Fino
Relating Predator Community Ecology And Duck Nest Survival In Eastern South Dakota, Samantha R. Fino
Electronic Theses and Dissertations
As conversion of native grasslands and wetlands to croplands continues in the Prairie Pothole Region (PPR), managers are tasked with maintaining sustainable waterfowl populations. Mesopredator community dynamics is a hypothesized mechanism driving spatiotemporal variation of waterfowl nest survival in the PPR, yet studies often lack detailed information on mesopredator species occurrence and abundance. Therefore, understanding spatial and temporal variation in behaviors of mesopredators provides valuable insights for understanding predator-prey interactions between mesopredators and upland duck nests. Further, differences in a predator community resulting from lethal removal of dominant species may influence composition and space use patterns of subordinate and non-target …
Factors Influencing Mortality Of Bighorn Sheep (Ovis Canadensis), Emily Moberg
Factors Influencing Mortality Of Bighorn Sheep (Ovis Canadensis), Emily Moberg
Electronic Theses and Dissertations
Reintroduced bighorn sheep (Ovis canadensis) in Nebraska faced a devastating pneumonia epizootic resulting in variable ewe reproductive success and poor lamb recruitment in many of the herds. From 2015-2017, no lamb recruitment was observed in the northern Pine Ridge subpopulation and as many as 60% of adults died. This was in stark contrast to the healthier Wildcat Hills herds to the south, where lamb recruitment was estimated to be between 50-70% during the same years. From 2018-2020, we radio-collared and recaptured 76 adult female bighorn sheep from 2 of 3 Pine Ridge herds and 1 of 2 Wildcat Hills herds. …
Investigating Dormancy And Germination Characteristics To Promote Restoration Success In The Northern Great Plains, Gregory A. Cooper
Investigating Dormancy And Germination Characteristics To Promote Restoration Success In The Northern Great Plains, Gregory A. Cooper
Electronic Theses and Dissertations
Failures in seed-based restoration can be partially attributed to a lack of knowledge on seed dormancy. Dormancy is beneficial for plant establishment in unpredictable environmental conditions, but a lack of uniform germination can hinder restoration efforts. The purpose of this research was to gain a better understanding of dormancy displayed by select forbs of the northern Great Plains. The first data chapter attempted to identify and break dormancy class. Seeds were treated with scarification, smoke, and fertilizer pretreatments in an attempt to break seed dormancy. Seeds were also placed in spring and summer temperatures to identify how seasonal phenology influenced …
Effects Of Agricultural Chemicals On Native Plants Of The Northern Great Plains, Gabrielle Bolwerk
Effects Of Agricultural Chemicals On Native Plants Of The Northern Great Plains, Gabrielle Bolwerk
Electronic Theses and Dissertations
Agricultural chemicals are ubiquitous on the Northern Great Plains landscape and have negative impacts on non-target plant communities, even at small doses. Northern Great Plains grassland plant communities may experience herbicide drift from agricultural fields or be subject to livestock pharmaceuticals in grazing lands. My research objective was to evaluate if and how native plants are affected by agricultural chemical presence at different concentrations. In Chapter 2, I studied the effect of different concentrations of three common agricultural herbicides (2,4-D, atrazine, and trifluralin) on the germination, emergence, and growth of native plant species of the Northern Great Plains. I performed …
C3 And C4 Grass Dominated Plant Communities Differ In Response To Future Larger And Less Frequent Rainfall, Zigeng Chen
C3 And C4 Grass Dominated Plant Communities Differ In Response To Future Larger And Less Frequent Rainfall, Zigeng Chen
Electronic Theses and Dissertations
Climate change is leading to larger and less frequent rainfall in the Northern Great Plains (NGP). We ask if this change in rainfall would influence carbon (C) and nitrogen (N) cycling in the NGP. First, we collected soils from C3 and C4 grass dominated plant communities from western South Dakota and conducted an incubation experiment to explore the effects of soil water content (SWC) and temperature on soil respiration (Rs) and N mineralization rate (ΔIN). Second, we conducted a three-year rainfallmanipulation (RaMP) experiment with two distinct rainfall regimes (frequent/small and infrequent/large events with constant total monthly precipitation) and two grasses …
Ecological Impacts Of Anthropogenic Chemicals On Non-Target Species And The Role Of Plant Diversity In Ecosystem Restoration And Resilience, Shiva Torabian
Ecological Impacts Of Anthropogenic Chemicals On Non-Target Species And The Role Of Plant Diversity In Ecosystem Restoration And Resilience, Shiva Torabian
Electronic Theses and Dissertations
Understanding ecosystem processes in rangelands is of paramount importance for ensuring global food security, given their pivotal role in sustaining forage and livestock production. Central to this understanding are fundamental processes such as nutrient cycling, decomposition, and plant biomass dynamics. However, the use of anthropogenic chemicals in agricultural practices has the potential to exert significant influence on these critical ecosystem functions. A pivotal factor in this context is the plant diversity inherent to these rangeland ecosystems. Plant diversity not only provides essential ecosystem functions but also enhances them with the capacity to withstand and recover from perturbations. Ecosystems characterized by …
Microplastic Accumulation In The Digestive Tract Of Young-Of-Year Atlantic Sharpnose Sharks (Rhizoprionodon Terraenovae) In The Grand Strand, Sc, Andrew Curtis Sitlinger
Microplastic Accumulation In The Digestive Tract Of Young-Of-Year Atlantic Sharpnose Sharks (Rhizoprionodon Terraenovae) In The Grand Strand, Sc, Andrew Curtis Sitlinger
Electronic Theses and Dissertations
This study focused on the presence and accumulation of microplastic fibers in the digestive tract and livers of young-of-year Atlantic Sharpnose Sharks (Rhizopriondon terraenovae) from two sampling locations along the Grand Strand of South Carolina. R. terraenovae is a small, mesopredatory elasmobranch found abundantly along northwestern Atlantic Ocean coastlines. Thirty specimens of R. terraenovae were collected from May through August of 2020. Microplastics were found in all specimens. A total of 672 plastic particles were identified over the course of the study, with an average of 22.4 ± 10.5 (SD) plastics per specimen. The majority of the plastics were classified …
Fine-Scale Site Selection Of Strand-Feeding Common Bottlenose Dolphins (Tursiops Truncatus) And Their Prey, Deborah Kleinclaus
Fine-Scale Site Selection Of Strand-Feeding Common Bottlenose Dolphins (Tursiops Truncatus) And Their Prey, Deborah Kleinclaus
Electronic Theses and Dissertations
Strand-feeding is a unique, cooperative foraging strategy used by some common bottlenose dolphins (Tursiops truncatus) at low tide in South Carolina and Georgia salt marshes, where a group of dolphins charges schools of fish, thrusting them onto the bank with their bow wave and then capturing prey items onshore. Strand-feeding dolphins are estuarine residents and frequent predictable stranding sites, suggesting an intimate knowledge of the area. Dolphin behavior prior to stranding suggests they do not herd the fish before charging, but instead prey on fish already shoaling near the bank. The use of active acoustics from strand-feeders in order to …
Extraction, Analysis, And Comparison Of Microplastics In Sc Marsh Substrates, Austin G. Sige
Extraction, Analysis, And Comparison Of Microplastics In Sc Marsh Substrates, Austin G. Sige
Electronic Theses and Dissertations
The global, rapid increase in plastic production is a widespread problem for coastal environments such as marshes that present favorable conditions for plastic retention. This study looked at the microplastic abundance within three previously unstudied South Carolina marshes located in Myrtle Beach, Murrells Inlet, and Waties Island. A comparison between the microplastic types and abundances between locations provided knowledge about the impacts of sediment composition (sand, silt, clay, and organic matter) on microplastic sequestration. This study also produced a novel microplastic extraction methodology for cohesive marsh sediment that used elutriation to effectively break apart aggregates prior to chemical digestion and …
Distribution And Soil Characteristics Associated With The Neches River Rose-Mallow (Hibiscus Dasycalyx), Morgan E. Langlinais
Distribution And Soil Characteristics Associated With The Neches River Rose-Mallow (Hibiscus Dasycalyx), Morgan E. Langlinais
Electronic Theses and Dissertations
The Neches River rose-mallow, Hibiscus dasycalyx, is a rare herbaceous perennial endemic to East Texas. The threatened, obligate wetland species is currently at risk of being lost in the wild due to habitat loss, encroachment of nonnative and native plant species, and hybridization with two other Hibiscus congeners, Hibiscus laevis and Hibiscus moscheutos. Known locations of each of the three Hibiscus species were used to measure select soil characteristics and habitat variables associated with each of the rose-mallows. H. dasycalyx was concluded to be associated with more fertile soils and slightly more canopy coverage than H. laevis and …
Importance Of The Microhabitat And Microclimate Conditions In The Northern Gray-Cheeked Salamander (Plethodon Montanus) Across An Elevation Gradient, Trevor Chapman
Electronic Theses and Dissertations
The southern Appalachian Mountains have among the highest salamander diversity in the world, largely due to local speciation in the family Plethodontidae. Plethodontid salamanders (i.e., lungless salamanders) are particularly sensitive to habitat climate conditions due to their reliance on cutaneous respiration, and their immediate environmental conditions (microhabitat) likely influence their dispersion and activity more than the large-scale atmospheric conditions. The Northern Gray-cheeked salamander (Plethodon montanus) is restricted to high elevations in the Appalachian Mountains. Our goal was to investigate the relationship between P. montanus and its microhabitat by examining behavioral preference for climatic conditions, characterizing the microclimate with …
Light And Temperature Entrainment Of Two Circadian-Driven Behaviors In The Flesh Fly Sarcophaga Crassipalpis, Raven Ragsdale
Light And Temperature Entrainment Of Two Circadian-Driven Behaviors In The Flesh Fly Sarcophaga Crassipalpis, Raven Ragsdale
Electronic Theses and Dissertations
Circadian rhythms dictate the timing of both once-in-a-lifetime adult emergence (eclosion) and daily locomotor activity rhythms in the flesh fly S. crassipalpis. Light cycles are considered the primary environmental time cue (zeitgeber), but the life history of S. crassipalpis suggests that temperature cycles (thermocycles) may also play a key role. This work evaluates the efficacy of thermocycling as a zeitgeber in S. crassipalpis. We found that shifting both light and temperature cycles of sufficient amplitude affect the phasing of eclosion and locomotor activity, but result in different patterns. Additional experiments suggest greater thermocycle sensitivity during the late metamorphic …
Community Structure Analysis Of Turtles With Application To The Early Pliocene Gray Fossil Site, Julian Conley
Community Structure Analysis Of Turtles With Application To The Early Pliocene Gray Fossil Site, Julian Conley
Electronic Theses and Dissertations
Turtles are important components of ecosystems around the world, with diverse ecological niches and adaptations. However, there are few detailed studies of how turtle community structure reflects local environments. This project applied techniques of community structure analysis to sites across the United States to infer past ecosystem and environmental conditions of the early Pliocene Gray Fossil Site (GFS) in northeastern Tennessee based on the ancient turtle community. Results indicate extant turtle community structure closely reflects environmental conditions, and that ancient turtle communities can be used to infer climate and habitat conditions of past ecosystems. Application to the GFS turtle community …
Evaluating Bat Roost Abundance: A Comparison Of Drone-Acquired Thermal Imagery And Acoustic Estimates With Visual Observations, Karah Jaffe
Electronic Theses and Dissertations
Roosts provide an opportunity to census philopatric populations of bats. Comparing the efficacy of traditional methods with novel methods can provide guidance on the use of new technologies in the field. This project aims to compare the count efficacy of external emergence methodologies, i.e., drone-acquired thermal imagery, acoustic estimates, and visual counts. Surveys were conducted ten nights at two emergence sites and synchronized to compare counts. Acoustic estimates could not be established as there was a weak prediction of the linear relationship between root-mean-square pressure and emergence count; therefore, this method was removed from the comparative analysis. A linear mixed-effects …
The Paleoecology Of High-Elevation Bison In The Greater Yellowstone Ecosystem And Implications For Modern Bison Conservation, Darian Bouvier
The Paleoecology Of High-Elevation Bison In The Greater Yellowstone Ecosystem And Implications For Modern Bison Conservation, Darian Bouvier
Electronic Theses and Dissertations
The national mammal of the United States, the American Bison (Bison bison) was once nearly extinct. Populations have recovered to the degree that thousands roam the Great Plains today. Due to their large numbers and body size, this species has an oversized impact on the ecological communities where it lives and is considered a keystone herbivore in modern North American grasslands. This study explores the detailed, seasonally resolved, paleoecology of seven bison from the Greater Yellowstone Ecosystem during the Late Holocene through stable isotope analyses and species niche modeling. Isotopic analyses of δ13C, δ15N, …
Loggerhead Shrike Detectability And Occurrence In Coastal South Carolina Urban Areas, Michelle Krauser
Loggerhead Shrike Detectability And Occurrence In Coastal South Carolina Urban Areas, Michelle Krauser
Electronic Theses and Dissertations
Grassland birds, such as the loggerhead shrike (Lanius ludovicianus), are threatened by extensive land-use change, including urbanization. Loggerhead shrikes have been declining since the early 1900s and are rare or extirpated in portions of their former range. Obtaining reliable population estimates of loggerhead shrikes is important to identify demographic trends and ensure conservation decisions are based on an accurate assessment of their current status. Imperfect detection, or the inability to detect every shrike during a survey, can result in biased population estimates. Estimating detection probability is labor-intensive and requires assumptions that are difficult to satisfy in most field studies. Understanding …
Enzootic Trends Of Crassostrea Virginica And Perkinsus Marinus In North Inlet Estuary, South Carolina, Nico Martin D'Amico
Enzootic Trends Of Crassostrea Virginica And Perkinsus Marinus In North Inlet Estuary, South Carolina, Nico Martin D'Amico
Electronic Theses and Dissertations
The Eastern oyster (Crassostrea virginica) co-occurs with the protozoan parasite Perkinsus marinus (the causative agent for "Dermo") in US Atlantic and Gulf of Mexico estuaries. Oyster host functions as an ecological engineer and agent for benthic-pelagic coupling are compromised when P. marinus infections are common in populations (prevalence) and high in individuals (intensity). P. marinus infections in oysters from North Inlet estuary, South Carolina were quantified in relation to shell height (60-76 mm, ≥76 mm), sex (functional female, male, indeterminate), water temperature, and salinity. Three fringing reefs on a longitudinal transect from the inlet mouth into the watershed were sampled …
A Review Of Current Methods In Avian Dietary Analysis And Their Integrated Application To Characterize The Trophic Niche Of Louisiana Waterthrush (Parkesia Motacilla)., Brandon Hoenig
Electronic Theses and Dissertations
Characterizing a species’ dietary composition presents an avenue to understand many facets of its ecological niche and can provide essential information for the species’ long-term conservation. To date, the vast majority of diet studies have relied on direct identification of prey during foraging observations or from diet samples to characterize the dietary habits of birds. However, advancements in laboratory-based approaches have revolutionized the field of trophic ecology by allowing researchers to indirectly infer dietary habits with higher resolution across greater time scales. Here, I apply two of these laboratory-based techniques, namely DNA metabarcoding and stable isotope analysis, to characterize the …
Analysis Of Water Quality And Fish Communities Of Crooked Creek, Tributary To The Allegheny River In Southwestern Pennsylvania, Katherine Stupar
Analysis Of Water Quality And Fish Communities Of Crooked Creek, Tributary To The Allegheny River In Southwestern Pennsylvania, Katherine Stupar
Electronic Theses and Dissertations
Crooked Creek is a tributary of the Allegheny River with a drainage area of 292 square miles. It has been historically affected by mine drainage pollution. Extensive cleanup and monitoring efforts by the Commonwealth of Pennsylvania and the U.S. Army Corps of Engineers (USACE) have taken place over the last four decades. Unconventional oil extraction, or fracking, presents an emerging threat to the water quality of this stream and the health of its fish communities. Here we perform an analysis of the Crooked Creek watershed utilizing backpack electrofishing, eDNA metabarcoding, and various methods of water quality analysis. Seven sites on …
Detection, Occupancy, Abundance, And Mercury Accumulation Of The Alligator Snapping Turtle (Macrochelys Temminckii) In Texas, David Rosenbaum
Detection, Occupancy, Abundance, And Mercury Accumulation Of The Alligator Snapping Turtle (Macrochelys Temminckii) In Texas, David Rosenbaum
Electronic Theses and Dissertations
Land use practices and physical alterations of ecosystems result in habitat loss and fragmentation, while chemical alterations, such as pollutant input, reduce habitat quality and health of exposed organisms. Here, I investigated the effects of watershed- and local-scale environmental variables on the occupancy, abundance, and mercury accumulation of a threatened aquatic species (Macrochelys temminckii, i.e., alligator snapping turtle) within the southwestern periphery of its distribution. Hierarchical modeling suggested the distribution of the species is more affected by watershed-scale land-cover than local habitat, and provided a baseline estimate of average species abundance across its range in eastern Texas. Abundance …
Detection And Occurrence Of Nerodia Harteri (Serpentes: Colubridae) In An Upper Portion Of The Brazos River Watershed, Jessica Yates
Detection And Occurrence Of Nerodia Harteri (Serpentes: Colubridae) In An Upper Portion Of The Brazos River Watershed, Jessica Yates
Electronic Theses and Dissertations
Semiaquatic snakes are disproportionately impacted by habitat alteration adjacent to wetlands because of their reliance on both terrestrial and aquatic habitats. Brazos River Watersnakes, Nerodia harteri, are endemic natricines with one of the most restricted geographic ranges in North America. I quantified detection and site occupancy probabilities of N. harteri and its sympatric congeners (N. erythrogaster and N. rhombifer), as well as microhabitat selection within the Nerodia community. Within occupied transects, search effort was positively correlated with detecting N. harteri, whereas environmental and/or habitat variables were better predictors for detecting the sympatric congeners. Microhabitat selection between …
Assessing The Live Bait Industry And The Ecological Status Of Invasive Cyprinodontiformes (Sheepshead Minnow: Cyprinodon Variegatus And Gulf Killifish: Fundulus Grandis) In Texas Streams, Erin Shepta
Electronic Theses and Dissertations
The introduction of invasive species is one of the greatest threats to global biodiversity. Once established, invasive species often cause irreversible ecological damage on native communities. Here, I investigated the pathway of introduction and ecological impacts of the sheepshead minnow (C. variegatus) and the gulf killifish (F. grandis). Both species were thought to have been introduced into inland Texas waters via bait-bucket releases and have caused native populations of their inland congeners to decline. While I did not find evidence that either species were being sold in inland shops, bait industry experts did reveal other potentially …
An Application Of Differential Mathematical Modeling Techniques To Study The Ongoing Rabies Epizootic In China, Christopher Turner
An Application Of Differential Mathematical Modeling Techniques To Study The Ongoing Rabies Epizootic In China, Christopher Turner
Electronic Theses and Dissertations
Rabies remains a global public health issue with a wide variety of neurological symptoms such as confusion, slight paralysis, hypersalivation, and hydrophobia. Rabies is usually fatal once symptoms appear. Many species are reservoirs for rabies, such as foxes, racoons, and wild dogs, which in turn can transmit the disease to humans, leading to complex transmission chains. There is a long latent period of rabies, between 1 to 3 months after infection, which further complicates control efforts. Mathematical modeling is a valuable tool in the study of infectious disease outbreaks and there have been many models applied to rabies outbreaks. However, …
Plant-Pollinator Communities Responsive To Local And Landscape Level Factors In Grassland Restorations., Aaron Sexton
Plant-Pollinator Communities Responsive To Local And Landscape Level Factors In Grassland Restorations., Aaron Sexton
Electronic Theses and Dissertations
As humans continue to degrade natural ecosystems via greenhouse gas emissions and habitat destruction, many species are being pushed to the brink of extinction. In hopes to offset this degradation, habitat restoration attempts to restore ecosystem function to an improved state resembling intact, remnant values. This is a difficult, but important, undertaking with factors to consider at multiple spatial and temporal scales. The restoration and conservation of pollinator communities has garnered heightened attention because of the valuable ecosystem services they provide. This dissertation investigates the local and landscape level factors of grassland restorations that influence plant-pollinator communities. I used a …
Fish Community Assembly At Multiple Spatial Scales In East Texas Streams, Jake R. Swanson
Fish Community Assembly At Multiple Spatial Scales In East Texas Streams, Jake R. Swanson
Electronic Theses and Dissertations
Stream communities are structured by environmental processes that vary in strength across different spatiotemporal scales. Therefore, revealing how stream fish communities are influenced by environmental gradients may clarify how communities respond to disturbance associated with anthropogenic change. I investigated the relative role environmental variables play in the processes that structure the taxonomic and functional diversity of stream fish communities, as well as historical trends in occurrence and local habitat associated with a species of greatest conservation need within east Texas. The results of this study indicate that stream sites with more habitat complexity and stability support a more taxonomically and …
Risk-Prone And Risk-Averse Foraging Strategies Enable Niche Partitioning By Two Diurnal Orb-Weaving Spider Species, Mitchell D. Long
Risk-Prone And Risk-Averse Foraging Strategies Enable Niche Partitioning By Two Diurnal Orb-Weaving Spider Species, Mitchell D. Long
Electronic Theses and Dissertations
Niche partitioning is a major component in understanding community ecology and how ecologically similar species coexist. Temporal and spatial partitioning and differences in foraging strategy, including sensitivity to risk (variance), likely contribute to partitioning as well. Here, we approach this partitioning with fine resolution to investigate differences in overall strategy between two species of diurnal, orb-weaving spiders, Verrucosa arenata and Micrathena gracilis (Araneae: Araneidae), that share similar spatial positioning, temporal foraging window, and prey. Through field observation, we found that V. arenata individuals appear to increase spatial and temporal sampling to compensate for an overall risk-prone strategy that depends on …
Spatiotemporal Factors Affecting The Occupancy And Phenology Of A Declining Songbird (Bachman's Sparrow - Peucaea Aestivalis) At The Western Extent Of Its Range, Liam G. Wolff
Electronic Theses and Dissertations
The Bachman’s Sparrow (Peucaea aestivalis) is a declining songbird that occurs throughout the southeastern United States. Bachman’s Sparrow is a Species of Greatest Conservation Need in Texas, but information crucial to management efforts, such as factors affecting their detectability and occupancy, is lacking. I investigated the predictors of Bachman’s Sparrow occupancy and phenology in Texas using detections from autonomous recording units coupled with site characteristics and weather data. My results indicate that Bachman’s Sparrow occupancy is associated with increasing herbaceous ground cover and decreasing basal area, distance to the nearest source population, and basal area when canopy height …
Responses Of Arthropods To Fire And How Pollinators And Pollination Services Are Affected By Fire Severity, Blyssalyn V. Bieber
Responses Of Arthropods To Fire And How Pollinators And Pollination Services Are Affected By Fire Severity, Blyssalyn V. Bieber
Electronic Theses and Dissertations
Fires impact ecosystems globally and due to climate change, there are shifts in fire regimes that impact ecological communities which provide essential ecosystem services. Focusing on arthropods, fire can influence this ubiquitous animal group in various way. We performed a comprehensive meta-analysis evaluating how fires impact differing arthropod functional groups. We found that overall, fire negatively effects community level responses for most functional groups with herbivores as the only exception showing some positive effects of fire. We also studied mixed-severity fires that burned >20 years ago and compared floral visitor communities across fire severities. We implemented a pollinator exclusion experiment …
Environmental Gradients Impact Key Leaf Traits In Riparian Trees, Amanda Malone
Environmental Gradients Impact Key Leaf Traits In Riparian Trees, Amanda Malone
Electronic Theses and Dissertations
Specific leaf area (SLA) reflects a plant’s carbon investment per area and relates to generalized leaf economics spectrum growth strategies (LES). To fill gaps of knowledge about intraspecific SLA variation and why it is often inconsistent with the LES, we studied the response of two riparian tree species along the urban-rural gradient in Northeastern Colorado: an invasive, nitrogen-fixer with broad tolerances and a nitrogen-limited and shade-intolerant native. Despite these differences, the two species responded similarly, apart from the response to the urban-rural gradient, in which lower nitrogen in rural areas was associated with a more conservative strategy in the native …
Morphological Variation And Community Science In Orthoptera, Amy Byerly
Morphological Variation And Community Science In Orthoptera, Amy Byerly
Electronic Theses and Dissertations
Patterns of morphological divergence across species’ ranges provide insight into local adaptation and speciation. Here, we compare phenotypic divergence among 4,221 crickets from 337 populations of two related species of field cricket, Gryllus firmus and G. pennsylvanicus and their hybrids. We find that these species differ across their geographic range in key morphological traits, such as body size and ovipositor length, and we directly compare phenotype with genotype for a subset of crickets demonstrating nuclear genetic introgression, phenotypic intermediacy of hybrids, and essentially unidirectional mitochondrial introgression. We discuss how these morphological traits relate to life history differences between the species. …