Course Overview
This study was performed in one section of a large-enrollment (1,300 students per quarter) gateway majors introductory biology course focused on evolutionary and ecological concepts at a large research university in the western United States. The course is the first in the introductory series and is a prerequisite for a large number of upper division courses in a wide variety of STEM majors. Enrollment is split across 2-3 sections, ranging in size from 200-500 students. The course consists of the following weekly meetings: three 50-minute lectures (full enrollment), one 50-minute ‘discussion’ (full enrollment, often treated as a fourth lecture), and one 180-minute laboratory (24 students per lab section). The campus is a Research-1 land-grant Hispanic-serving institution of over 30,000 undergraduate students and structures its academic year into three 10-week sessions. The course covers introductory content in evolution and ecology, including concepts relating to species interactions, functional diversity, population genetics, and natural selection, as well as skill-based content such as hypothesis testing and data interpretation. It meets the campus literacy requirements for instruction in visual literacy, scientific literacy, and quantitative literacy.
The course learning objectives (CLOs) are:
  1. Explain what climate is, what causes it, how it is changing, and how it influences the distribution and abundance of organisms.
  2. Explain what biodiversity is and describe how it is measured.
  3. Predict how human activities such as overharvesting, habitat destruction, and pollution will affect the diversity and composition of ecological communities and the evolutionary trajectory of species.
  4. Describe the concept of a tradeoff and give examples, explaining how specific tradeoffs relate to the maintenance of species diversity in nature.
  5. Use the fundamental principles of inheritance to explain the relationship between genotype and phenotype in parents and offspring.
  6. Distinguish the processes that lead to limited and unlimited population growth and give examples of factors that limit growth for natural populations.
  7. Predict the direction, magnitude and outcomes of natural selection given a set of biological starting conditions.
  8. Describe the contributions that different forms of natural and other forms of selection and genetic drift make to evolutionary change.
  9. Use data from population genetics, natural selection, biogeography, and phylogenetics to explain how new species arise.
  10. Explain how competition, predation and mutualism each influence the distribution and abundance of species over time and space.
  11. Develop a conceptual framework for global carbon cycling that integrates photosynthesis, primary production, herbivory, decomposition, and the burning of fossil fuels.
  12. Interpret graphs and data to evaluate scientific hypotheses, models and theory for any of the content-based objectives above (1-11).
Historically, the discussion sessions have been treated as an additional lecture and do not differ from the structure and style of the formal lecture sessions. They include the full course enrollment and so are not a true discussion format (e.g. as described in White & Kolber 1978). The lead author (LMG) joined the course instructional team in the fall of 2017 and has taught the course 6 times to over 1,800 students. In 2018, LMG instituted a course redesign in which the discussion sessions transitioned into flipped case-studies of campus faculty research relevant to the course. The goals of the redesigned discussion sessions were to 1) practice the scientific method (predicting/interpreting results, accepting/rejecting hypotheses, etc); 2) introduce students to current scientists and active research programs relevant to course content, with a focus on diverse representation*; and 3) illustrate to students the ‘cutting edge’ of research. The redesigned discussion sessions include weekly homework assignments intended to introduce students to how scientists study the topic to be discussed that week. The homework assignments also serve to restructure point values for the course to include more low-stakes formative assessments, which has been shown to reduce or remove achievement gaps in introductory biology courses (Eddy & Hogan 2014; Haak et al. 2011).