Ecology and Evolutionary Biology Commons^™

From Flight To Hatching: Adult Sexual Dimorphism, Life History, And Egg-Stage Ecology Of Pseudocotalpa Giulianii, Mandylene Mountain

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Nevada endemic dune beetle Pseudocotalpa giulianii is currently known only from two dune systems in Amargosa Valley, Nevada, yet much of its life cycle occurs below the sand surface and remains poorly documented. This thesis addresses key gaps in adult-stage biology and egg-stage development that are relevant to understanding reproduction, vulnerability, and habitat requirements in this dunerestricted species.

To characterize adult sexual dimorphism and life history, I quantified morphological differences between males and females and measured sex-specific adult survival under laboratory conditions relative to the aboveground flight season. Males and females overlapped broadly in external body size, but tarsal …

Thermal Physiological Ecology Of The Relict Leopard Frog At Hot And Cold Springs, Robert P. Pelletier Iii

UNLV Theses, Dissertations, Professional Papers, and Capstones

The relict leopard frog (Rana onca) once ranged across drainages in southern Nevada, northwestern Arizona, and southwestern Utah. Following a decline, the species only persisted in a few geothermally influenced hot springs, which led to the perspective that hot springs were high-quality habitat. Rana onca has been under intensive, multiagency management and the species has been translocated to establish additional populations, including at cold-water sites. Three research studies are presented into the thermal physiological ecology of R. onca with the aim of informing conservation strategy. The research was focused at a thermally influenced hot spring and a cold-water spring to …

Modeling The Mojave: A Multiphase, Mixed Methods Phenomenological Investigation Of Novice Understanding Of A Complex Ecological System, Nicole Juliana Thomas

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores early college science majors’ conceptions of the Mojave Desert ecosystem as a complex system. A multi-level, explanatory sequential mixed methods design was employed to study college science majors’ understanding of the Mojave Desert ecosystem to better inform science pedagogy. The first level, the quantitative phase of the study, consisted of developing a mathematical representation of twelve ecosystem variables present within the Mojave Desert. The second level, the qualitative phase of the study, consisted of phenomenological semi-structured interviews with 23 early college science majors. The findings of this research suggest that the Mojave Desert operates as a complex, …

Enviromental Dna (Edna) Tools For Invasive Mosquitofish (Gambusia Affinis) Surveillance At The Shoshone Pupfish (Cyprinidon Nevadensis Shoshone) Refugium, Yusuf Olamilekan Umar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring-fed aquatic ecosystems of the North American Southwest and U.S. Great Basin hosts a plethora of endemic fish species due to the effects of hydrologic fragmentation that resulted from Pleistocene aridification. Threats to endemic fishes worldwide include human intentional or unintentional release of exotic species into their habitats. Early detection of invasive species, while corrective actions are still possible, is critical for management, yet traditional survey methods are often disruptive to sensitive ecosystems, costly, and limited in sensitivity. The recent development of environmental DNA (eDNA) approaches offers powerful alternatives for invasive species monitoring in aquatic systems. In this study, a …

Niche Conservatism And Sympatric Parallel Evolution May Help To Maintain Eight Nascent Tree Taxa Along A Sharp Elevation Gradient, Elizabeth A. Stacy, Rebecca Ostertag

Life Sciences Faculty Research

1. Patterns of niche partitioning among closely related taxa, such as those in incipient adaptive radiations, can provide clues into how niches are created, partitioned, and integrated over ecological and evolutionary time scales. Hawaiian Metrosideros is a ~3-MYO adaptive radiation of trees that dominates the Hawaiian Islands in continuous stands within islands and allows examination of niche partitioning at the early stages of adaptive radiation.
2. We monitored growth and survivorship over 2 years of seedlings derived from open-pollinated fruits of eight Metrosideros taxa distributed along the elevation gradient of Koʻolau Volcano, Oʻahu, under four combinations of light and phosphorus. We included …

Climate And Gypsum Parent Material Shape Biocrust Communities And Moss Ecology In The Chihuahuan And Mojave Deserts, Nicole Pietrasiak, Katelyn G. Gobbie, Brian Jusko, Rebecca E. Drenovsky

Life Sciences Faculty Research

Biological soil crust communities (biocrusts) establishing on gypsum soils have been well-documented for their prolific appearance and rich diversity of lichens and bryophytes. However, studies characterizing gypsum biocrusts have occurred primarily outside of the U.S., most of which lack comparisons to other soil types. We conducted intensive field surveys to evaluate the ground cover and frequency of biocrust functional groups and moss species on gypsum and non-gypsum soils in the U.S. regions with the most extensive gypsum outcrops, the northern Chihuahuan and eastern Mojave Deserts. Study sites were stratified by geomorphology and paired, so that every gypsum site was matched …

The Utilization Of String Pulling To Determine Female Rats' Dual Cognitive Motor Task Performance Following Space Flight Stressor Exposure, Doc-Haden Rodgers, Nicole M. Atttallah, Teresa L. Garcia, Nuhamine A. Moges, N. A. Moges, K. D. Omengan, J. F. Cortez, K. S. Dhede, A. A. Blackwell

Undergraduate Research Symposium Posters

During deep space exploration, astronauts depend on mission-essential performance in Dual Cognitive Motor Tasks (DCMT), such as receiving information from ground control to assemble and configure wires during a spacewalk. DCMT relies upon processing cognitive and motor information simultaneously. Previous research on rodent models has shown various impairments in cognition and motor function in separate tasks after exposure to deep space radiation and sleep fragmentation (SF). However, an assessment of DCMT performance in rodents has not been established. Rats and humans use similar hand-over-hand movements to pull a string, and task demands may be varied to assess cognition and motor …

The Characterization Of Cooperative String-Pullung Behavior In Rats After Exposure To Space Flight Stressors, Teresa L. Garcia, Nuhamine A. Moges, Sierra Ordonez, Nicole M. Attallah, D. H. Rodgers, A. Adhikari, K. D. Omengan, D. Lloyd, S. L. Gleed, A. A. Blackwell

Undergraduate Research Symposium Posters

Astronauts work cooperatively to complete tasks on missions through deep space where they will experience stressors, including radiation and sleep fragmentation, that may impair performance. Animals work together to achieve a common goal during cooperative tasks using string-pulling behaviors. While string-pulling behavior has revealed deficits in rat sensorimotor function after exposure to space flight stressors, it has yet to be determined if rats will engage in cooperative string-pulling or if these stressors will influence cooperation. Thus, to explore how space flight stressors impact cooperative behavior, female Wistar rats were exposed to either sham (n = 8) or 10 centi-grays of …

Assessing Ectomycorrhizal Advantage On Tree Species Within Differing Soil Materials In Spring Mountains, Nevada, Kirsten Soriano, Riley Jones, Daniel Thompson

Undergraduate Research Symposium Posters

Ectomycorrhizal fungi (ECM) form symbiotic relationships with their partner plant, creating root systems which allow for the exchange of nutrients among connected plants. The Spring Mountains National Recreation Area (NRA) in Southern Nevada is the study site for examining ECMs due to its diverse ecosystem with numerous inhabiting species. To assess the effects of ECMs on the tree composition, literature review was conducted to outline previous methods. Through data analysis and observations of the sample sites, it is concluded that ECMs are highly likely to have an effect on tree composition of the Spring Mountains NRA. The purpose of this …

Effect Of Macronutrients On A Rat Model Of Clostridioides Difficile Infection, Stephanie Yang, Maria Niamba, Rose Jiang, Ashton Wippel, Efren Heredia, Liliko Watanabe, Katrina Valadez, Erica Bacab, Ernesto Abel-Santos

Undergraduate Research Symposium Posters

Clostridioides difficile (C. diff) is an anaerobic, spore forming, gram-positive bacteria. C. diff is the causative agent of C. difficile infections (CDIs) and is recognized as the leading cause of nosocomial infective diarrhea worldwide. CDI is associated with the use of antibiotics that alter the gut microbiome and C. diff resides in the large intestine where onset of the disease then occurs. Having observed the impacts of CDI on mice models, the Abel-Santos lab now shifts to observing this infectious disease in rat models. Establishing the infectious dosage at 109 spores, this study aims to identify the correlation between diet …

Effects Of Fire Temperatures On Mojave Desert Native And Nonnative Seeds, Sophia Lorenzana, Lindsay Chiquoine

Undergraduate Research Symposium Posters

Large-scale wildfires have been historically rare in hot deserts like the Mojave, largely due to the scarcity or uneven distribution of native plant biomass as fuel. Thus, native plants in these regions are ill-adapted to withstand spreading wildfire, resulting in slow post-fire recovery. Here, I test the hypothesis that nonnative grasses respond better to heat cues than native plant species. Seeds from 3 invasive and 13 native plant species were collected from research sites located in the eastern Mojave Desert, near surrounding Clark County Flood Control District weather stations. Seeds were buried in an artificial substrate mimicking field soil conditions …

Effects Of Low Dose Exposure To Radiation And Sleep Fragmentation On Discrimination In String-Pulling Behavior With Female Rats, Jonathan F. Cortez, Diana Lloyd, T. L. Garcia, A. Adhikari, N. M. Attallah, N. Moges, D. H. Rodgers, K. S. Dhede, K. D. Omengan, A. A. Blackwell

Undergraduate Research Symposium Posters

Astronauts will face harmful stressors, such as galactic cosmic radiation (GCR) and sleep fragmentation (SF), on a three-year space flight mission to Mars and back. Astronauts perform skilled reach-to-grasp behaviors on these missions, including interacting with controls to navigate the spacecraft. Recent work has shown that GCR and SF disrupt skilled reach-to-grasp behavior in rodent models; however, the underlying nature of these deficits is unknown. To determine if tactile sensation and proprioceptive feedback contribute to these impairments, this study evaluated the effects of radiation and SF exposure on memory and sensorimotor discrimination in a rodent model. Twenty-one outbred Wistar, retired …

Uvc And Planetary Habitability: Insights From Desert Lichens And Cyanobacteria, Tejinder Singh

UNLV Theses, Dissertations, Professional Papers, and Capstones

An important question in astrobiology is whether life can exist under the levels of UVC radiation found on Archean Earth, Mars, and exoplanets. We investigated this question by studying the UVC survival of colonial cyanobacterium and lichens that grow in harsh desert environments and possess natural sunscreens. We irradiated them nonstop in a desiccated state with a UVC flux closely representing the upper limit on those planets: 55-60 W/m². After irradiation, we rehydrated and assessed their survival using chlorophyll fluorometry and by counting the number of viable colonies that formed on agar plates. All three study organisms survived two to …

Effects Of Climate Change On (Semi)-Arid Ecosystems In The Southwestern United States, Charlotte Van Der Nagel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Climate change is considered amongst the most severe threats to terrestrial and aquatic ecosystems globally. Ecosystems in the southwestern United States have specifically been impacted by intense drought conditions since 2000. Higher temperatures combined with altered precipitation stresses many ecosystems; however, ecosystem specific responses to such stressors may vary. Here, the effects of climate change on semi-arid ecosystems are analyzed for some of the most vulnerable ecosystems in the southwestern United States: lacustrine, riparian, and dryland ecosystems.

Lakes and reservoirs in arid environments often serve as drinking water sources and recreational areas where high water quality is essential. Climate change …

Increasing Swim Instructors' Perceived Knowledge Of Sensory-Based Strategies When Coaching Children Who May Have Sensory Differences, Gabrielle Palmer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Although swim instructors are solely taught water safety regulations and correct swimming techniques, they are nonetheless viewed as mentors by the kids they work with. They are required to finish both their basic swim instructor (BSI) course and their cardiopulmonary resuscitation (CPR) certification, which primarily covers the fundamentals (American Red Cross Training Services, 2023; Kraft & Leblanc, 2018). However, neither provides a method of teaching swimming to children who might have sensory processing differences. This lack of education may affect both the child's participation and the swim instructor's capacity to impart knowledge. Research revealed that swim instructors are not very …

Plant-Plant Interaction In Early- Vs. Late-Successional Varieties Of The Hawaiian Landscape-Dominant Tree, Metrosideros Polymorpha, Tomoko Sakishima

UNLV Theses, Dissertations, Professional Papers, and Capstones

Plant-plant interactions play an important role in assembling plant communities. Interactions between neighboring plants can vary as a result of the genetic relatedness of neighbors, impacting rates of growth and patterns of resource allocation. When growing alongside close relatives, some species decrease their growth in a form of cooperation, while others grow faster through facilitation. A complication of plant interaction studies arises because decreased growth in the presence of close relatives can also be due to competition for resources, which increases with phenotypic similarity. Further complicating matters, mycorrhizal fungi, through their connections with plant roots, may strongly influence plant interactions. …

Seasonal Climate And Environmental Conditions Associated With Physiological Variations Of Southwestern United States Pines, Taylor Brewer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Juvenile and adult conifers in the southwestern United States are vulnerable to a range of different abiotic and biotic factors, yet it is unclear how their stress tolerance varies across environments. Predicted increases in the frequency and intensity of disturbance as well as greater climate and weather variability across the region highlight the potential for differential physiological responses across tree species and populations. This thesis focuses on two physiologic mechanisms, hydraulic vulnerability and mortality, that could be altered by climate change in two broadly distributed southwestern United States conifers: ponderosa pine and pinyon pine.

In chapter 2, I measured the …

The Behemoth Of The Last Ice Age: The Evolutionary Saga Of The Columbian Mammoth In North America, Nathaniel Valentine

Calvert Undergraduate Research Awards

The Columbian’s mammoth evolutionary history can be traced back to the origin of life and its evolutionary lineage can be tracked down by examining select species over geologic time. I conducted a literature review with multiple scientific journals to identify key transitional species that trace their lineage to the Columbian mammoth. Transitional species were selected from the Precambrian and the various periods of the Phanerozoic which exhibited vertebrate-like body structures and behaviors. Evidence suggests that early vertebrate-like animals were present by the Cambrian period. Mammal evolution would continue in the Mesozoic era and radiate in the Cenozoic era. The Columbian …

Informing Management Strategy For The Relict Leopard Frog (Rana Onca): Insights Into Breeding Biology And An Attempt To Improve Augmentation Success Through Pre-Exposure And Clearance Of An Emerging Amphibian Pathogen, Rebeca Rivera

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Relict Leopard Frog, Rana onca, is a species of conservation concern that suffered a decline sometime during the 20th century. Even after two decades of intensive management, the species currently only occupies 20 spring sites in southern Nevada and northwestern Arizona. The causes for the historical decline are mostly speculative, but relate to habitat loss, introduced predators, and emergent disease. Since 2001, R. onca has been under an intensive conservationprogram managed by a multiagency conservation team. There are several objectives specified in the program including the need to investigate the biology of the species and incorporate findings into …

Sequestered Sequences: A Bioinformatic Approach To The Forgotten Genome, Dylan Barth

UNLV Theses, Dissertations, Professional Papers, and Capstones

As high throughput sequencing generates ever increasing amounts of genetic and epigenetic data new lines of inquiry open up in the field of genomic research. In this thesis, we discuss three ways in which we can utilize public databases of next generation genomic data in order to study areas of the genome previously ignored by traditional approaches. These include the study of linker regions between domains of proteins, indirect enhancers that do not strongly contact promoters of genes they regulate, and transposon-derived enhancer elements. The work uncovers many exceptions to known biological principles, and adds nuance to our understanding of …

The Effects Of Big Dune And Lava Dune Sand Composition On The Eggs And Larvae Of Pseudocotalpa Giulianii, Cosset Hernandez Pena, Mandy Mountain, Daniel B. Thompson

Spectra Undergraduate Research Journal

Differences in the composition of aeolian sand at Big Dune and sand at Lava Dune that is mixed with basalt and various minerals may affect water retention and the development of insects that are specialized for living in sand environments. These two dunes, located in Nye County, Nevada, are home to the endemic dune scarab beetle, Pseudocotalpa giulianii (PSGU). The differences in sand type may influence the growth patterns of the eggs and larvae of this beetle species that hatches and develops to an adult within the sand. The purpose of this experiment is to test whether sand composition affects …

Synecological Response Of Spring Benthic Prokaryotes And Macroinvertebrates To Paleozoic Roof Pendant-Derived Calcium, Ariel D. Friel, Khaled Pordel, Zachary Meyers, Cale O. Seymour, Nicole J. Thomas, Fred M. Philips, Jeffrey R. Knott, Donald W. Sada, Laura Rademacher, Marty Frisbee, Brian P. Hedlund

Life Sciences Faculty Research

Despite the ecological significance of desert springs, little is known about relationships between spring hydrogeochemistry and ecology, particularly over multiple trophic levels. Here, we surveyed microbial communities (bacteria and archaea) and benthic macroinvertebrate (BMI) communities in springs that recharge through granitoid bedrock in Owens Valley, CA, to determine whether subtle geochemical differences imparted by metamorphosed roof pendant weathering in the source area affect spring ecosystems. Relative to other springs, roof-pendant-recharged springs were characterized by elevated (1) Ca2+/Na+, Ca2+/Mg2+, and divalent/monovalent cation ratios, (2) relative abundance of taxa inferred to be benthic aerobes and prosthecate/stalked bacteria, and (3) abundance and diversity …

The Effects Of Habitat Isolation On Fine-Scale Genetic And Geographic Structure Of Populations Of Two Threatened Endemic Insects In Southern Nevada, Pseudocotalpa Giulianii And Icaricia Shasta Charlestonensis, Kristen Tovar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Assessing the role geographic isolation and ecological specialization have on phylogeographic patterns contributes to our understanding of the evolutionary history of a species and the processes that erode genetic diversity. I used mitochondrial and nuclear genomic sequences to assess whether habitat isolation has shaped the fine-scale patterns of present-day genetic structure and diversity in two threatened insect species endemic to southern Nevada. Pseudocotalpa giulianii (Coleoptera; Scarabaeidae) is a dune obligate scarab beetle endemic to only two small, isolated sand dunes in Nye County, Nevada, with a usable habitat of less than 4.2 km sq that is impacted by on-going degradation. …

Growth Of Pseudocotalpa Giulianii Larvae In Sand From Different Dune Sources, Cosset Hernandez Pena, Mandy Mountain

Undergraduate Research Symposium Posters

Pseudocotalpa giulianii (PSGU) is an endemic species known to inhabit two sand dunes in Nye County, Nevada: Big Dune Recreational Area and Lava Dune. Differences in sand properties between Big Dune and Lava Dune could impact survival and growth of the larvae of P. giulianii. Use of permitted off-road vehicles (ORV) in Big Dune can impact its habitats and cause disturbances to local populations, including the Giuliani Dune Scarab as ORV activity is correlated with changes in dune vegetation. Lava Dune has no permitted ORV activity, however, differences in sand composition, including eroded basalt, have the potential to influence the …

Quantifying The Effect Of Disturbance On Native Mojave Desert Shrubs, Tamara J. Wynne

UNLV Theses, Dissertations, Professional Papers, and Capstones

Disturbance can come in many different forms. In our studies, we looked at the impact of a solar photovoltaic facility on native plants growing inside and outside of the facility, alteration in precipitation (simulated) on four native shrubs and the impact of applying supplemental water as a function of volume and frequency to establish native shrubs such as might occur at restoration sites. Disturbance is becoming a more common phenomenon in many ecosystems throughout the world, increasing the need for studies that quantify the impact at the plant and ecosystem level. Each research project revealed different plant responses, such as …

Human Arhgef9 Intellectual Disability Syndrome Is Phenocopied By A Mutation That Disrupts Collybistin Binding To The Gabaa Receptor Α2 Subunit, Dustin J. Hines, April Contreras, Betsua Garcia, Jeffrey S. Barker, Austin J. Boren, Cristelle Moufawad El Achlar, Stephen J. Moss, Rochelle M. Hines

Psychology Faculty Research

Enrichment of collybistin to parvalbumin positive clusters on the soma of pyramidal cells in mouse cortex. Collybistin (green) is strongly enriched at parvalbumin (red) clusters that surround the pyramidal cell soma. Collybistin remains enriched at the parvalbumin clusters on somas in the cortex of Gabra2-1 mice suggesting that collybistin is trafficked to these sites independent of interaction with the α2 subunit of GABAA receptors. For more information, please refer to the article by Hines et al. in this issue.

Not Only Severe Events: Moderate Dry Periods Impact The Hydraulic Functioning And Survival Of Planted Ponderosa Pine Seedlings, Carolyn R. Koehn, Matthew D. Petrie, Robert M. Hubbard

Life Sciences Faculty Research

Juvenile tree survival will increasingly shape the persistence of ponderosa pine forests in the western United States. In contrast to severe pulse disturbances that induce widespread adult and juvenile tree mortality, moderate periods of low rainfall and warm temperatures may reduce forest persistence by killing juvenile trees at the seedling stage. Intensification of these periods in a changing climate could therefore increasingly restrict both natural regeneration and artificial regeneration of planted seedlings. We conducted a controlled field experiment at a single site in the Front Range of Colorado, USA, to determine the responses and survival of 3 Colorado subpopulations of < 1 year old potted ponderosa pines to moderately dry conditions, variation in small rainfall events based on observed patterns, and shaded and unshaded microsite environments. Near surface soil moisture increased slightly following small rainfall events, but declined over the 45-day experimental period. Seedling transpiration and associated canopy cooling declined after ∼13 days, and further declines in transpiration and canopy cooling suggest that the majority of trees in lower rainfall treatments experienced hydraulic dysfunction between days ∼20–30. After 45 days, mortality across all subpopulations and treatments, inferred by relative water loss, exceeded 90–95%. Despite some uncertainty pertaining to the stress tolerance of nursery grown versus naturally germinated conifers, our results show that planted ponderosa pine seedlings < 1 year old are unlikely to survive moderate dry periods of 20+ days relying on small rainfall events. Although microsite conditions and soil moisture availability shaped tree hydraulic functioning early in the experiment (days 1–13), later functioning was shaped predominately by the legacy of rainfall treatments. Our results illustrate the importance of moderate dry events that occur consistently as part of seasonal variation in climate, and show how their intensification may constitute a sustained press that limits opportunities for natural and artificial regeneration.

Editorial: Ecology, Metabolism And Evolution Of Archaea-Perspectives From Proceedings Of The International Workshop On Geo-Omics Of Archaea, Brian P. Hedlund, Chuanlun Zhang, Fengping Wang, Christian Rinke, William F. Martin

Life Sciences Faculty Research

To facilitate global efforts in addressing fundamental questions related to the biology of archaea, an international consortium of experts organized the International Workshop on Geo-Omics of Archaea (IWGOA), with the overarching themes of Ecology/Biogeochemistry, Metabolism, and Evolution. The IWGOA was held in Shenzhen, China, from October 25th to 27th, 2019. The meeting was attended by more than 200 attendees from China, Japan, USA, Australia, Germany, and France. Some of the most exciting oral and poster presentations made at the IWGOA are celebrated in this Research Topic Figure 1. The 21 manuscripts herein span different aspects of archaeal biology in both …

A Stillness In The Desert? Engaging The Public Through An Immersive Exploration Of Southwest Soundscapes, Julian Kilker, Thomas Bjelic

Creative Collaborations

The pandemic highlighted the anthropocentric nature of soundscapes, while the recent popularity of electric cars, quadcopters, and “noise cancellation” earbuds demonstrated how consumer products can rapidly change our awareness of sound. While light pollution is already extensively addressed in scholarly research, popular works such as The End of Night, and public engagement such as The International Dark Sky Association, the complex interplay of sound, natural resources, and public engagement is still emerging, particularly in creative fields.

Two UNLV scholars and artists are collaborating on this project: Julian Kilker, who specializes in visual and emerging technology research, and Tom Bjelic, who …

The Energetics Of Uniquely Human Subsistence Strategies, Thomas S. Kraft, Vivek V. Venkataraman, Ian J. Wallace, Alyssa N. Crittenden, Nicholas B. Holowka, Jonathan Stieglitz, Jacob Harris, David A. Raichlen, Brian Wood, Michael Gurven, Herman Pontzer

Anthropology Faculty Research

The suite of derived human traits, including enlarged brains, elevated fertility rates, and long developmental periods and life spans, imposes extraordinarily high energetic costs relative to other great apes. How do human subsistence strategies accommodate our expanded energy budgets? We found that relative to other great apes, human hunter-gatherers and subsistence farmers spend more energy but less time on subsistence, acquire substantially more energy per hour, and achieve similar energy efficiencies. These findings revise our understanding of human energetic evolution by indicating that humans afford expanded energy budgets primarily by increasing rates of energy acquisition, not through energy-saving adaptations such …