Laci Gerhart

University of California, Davis | UCD · Department of Evolution & Ecology

Online educational videos have the potential to enhance undergraduate biology learning, for example by showcasing contemporary scientific research and providing content coverage. Here, we describe the integration of nine videos into a large-enrollment (n = 356) introductory evolution and ecology course via weekly homework assignments. We predicted...

Experience and training in field work are critical components of undergraduate education in ecology, and many university courses incorporate field‐based or experiential components into the curriculum in order to provide students hands‐on experience. Due to the onset of the COVID‐19 pandemic and the sudden shift to remote instruction in the spring o...

The 2019 Undergraduate Biology Education Research Gordon Research Conference (UBER GRC), titled "Achieving Widespread Improvement in Undergraduate Education," brought together a diverse group of researchers and practitioners working to identify, promote, and understand widespread adoption of evidence-based teaching, learning, and success strategies...

Forests cover 30% of the terrestrial Earth surface and are a major component of the global carbon (C) cycle. Humans have doubled the amount of global reactive nitrogen (N), increasing deposition of N onto forests worldwide. However, other global changes—especially climate change and elevated atmospheric carbon dioxide concentrations—are increasing...

The frequency of extreme warm years is increasing across the majority of the planet. Shifts in plant phenology in response to extreme years can influence plant survival, productivity, and synchrony with pollinators/herbivores. Despite extensive work on plant phenological responses to climate change, little is known about responses to extreme warm y...

Isotopic measurements on junipers growing in southern California during the last glacial, when the ambient atmospheric [CO2] (ca) was ~180 ppm, show the leaf-internal [CO2] (ci) was approaching the modern CO2 compensation point for C3 plants. Despite this, stem growth rates were similar to today. Using a coupled light-use efficiency and tree growth...

Disturbances affect almost all terrestrial ecosystems, but it has been difficult to identify general principles regarding these influences. To improve our understanding of the long-term consequences of disturbance on terrestrial ecosystems, we present a conceptual framework that analyzes disturbances by their biogeochemical impacts. We posit that t...

Background/Question/Methods Extreme years in which temperatures are anomalously high are occurring much more frequently than in the past. Recent studies show extreme years, which occurred about 33% on average during 1951-1980, are now occurring approximately 75% of the time. Plants are expected to be increasingly more affected by extreme years as...

A novel protocol to purify bone collagen for radiocarbon dating and stable isotope ratio analysis from asphalt-impregnated skeletal remains stored in the George C. Page Museum of La Brea Discoveries (Los Angeles, California) is presented. This simple technique requires that bones be crushed (1-2 mm), sonicated in a 2:1 toluene/methanol solution, an...

Although recent anthropogenic effects on the global nitrogen (N) cycle have been significant, the consequences of increased anthropogenic N on terrestrial ecosystems are unclear. Studies of the impact of increased reactive N on forest ecosystems-impacts on hydrologic and gaseous loss pathways, retention capacity, and even net primary productivity-h...

Danaus plexippus) have a unique yearly life cycle, in which successive generations breed and move northward from the southern USA in spring to the northern US and southern Canada by late summer; they overwinter in extremely restricted areas in central Mexico and along the California coast. Mexican overwintering frequency owing to climate change. He...

Monarch butterflies (Danaus plexippus) have a unique yearly life cycle, in which successive generations breed and move northward from the southern USA in spring to the northern US and southern Canada by late summer; they overwinter in extremely restricted areas in central Mexico and along the California coast. Mexican overwintering populations have...

Background/Question/Methods During the Last Glacial Maximum, atmospheric [CO2] was as low as 180 ppm and has currently risen to a modern value of 393 ppm as a result of fossil fuel combustion and deforestation. Past research has shown that glacial trees had ci values (inter-cellular CO2 concentrations) less than half that of modern trees, suggest...

• While studies of modern plants indicate negative responses to low [CO₂] that occurred during the last glacial period, studies with glacial plant material that incorporate evolutionary responses are rare. In this study, physiological responses to changing [CO₂] were compared between glacial (La Brea tar pits) and modern Juniperus trees from southe...

During the Last Glacial Maximum, atmospheric [CO2] was as low as 180 ppm and has currently risen to a modern value of 393 ppm as a result of fossil fuel combustion and deforestation. In order to understand how changing [CO2] influenced trees over the last 50,000 years, we analyzed carbon isotope ratios and width of individual tree rings from glacia...

During the Last Glacial Maximum (LGM; 18,000-20,000 yr ago) and previous glacial periods, atmospheric [CO(2)] dropped to 180-190 ppm, which is among the lowest concentrations that occurred during the evolution of land plants. Modern atmospheric CO(2) concentrations ([CO(2)]) are more than twice those of the LGM and 45% higher than pre-industrial co...

Background/Question/Methods During the last ice age, atmospheric CO2 concentrations were approximately 180 ppm and have currently risen to a modern value of 385 ppm as a result of fossil fuel combustion and deforestation. In order to understand how changing CO2 concentrations influenced the growth of trees over evolutionary time scales, we studied...