Chapter One

What is macroevolution? What is macroecology?

Why study macroevolution and macroecology? Most textbooks on evolution and ecology largely focus on processes operating within populations. But many of the questions we want to ask about patterns of biodiversity are not easily answered by only focuIntssing on the population level, such as: how does novelty arise? what causes mass extinctions? does selection act at the level of genes, individuals, species or lineages? why is biodiversity distributed so unevenly in space? Questions like these require us to build upon our knowledge of micro-level processes, but consider them on macro-level scale, over large spatial scales, long periods of evolutionary history, and over many different evolutionary lineages. Studying the intellectual development of the fields of macroevolution and macroecology is important for several reasons. Scientific ideas evolve over time, building on what has come before, so we can’t fully understand what people think today without appreciating how that point of view has been constructed over by research and contemplation over long periods. Many of the same areas of debate come up again and again, so a familiarity with history helps us to recognize and evaluate different hypotheses. This chapter will also show how the individual case studies covered in the rest of the chapters connect to the bigger picture of evolutionary and ecological ideas.

What are the main points?

• Macroevolution focuses on changing patterns of biological diversity across time, space and lineages
• Macroecology concerns broad-scale patterns in the abundance and distribution of species.
• Key debates resurface again and again, such as whether change happens gradually by accumulation of small changes or quickly by larger “leaps”, and the relative roles of chance, selection and history in shaping biodiversity.

What techniques are covered?

• Development of ideas: what we think now builds upon what scientists have thought in the past, so we need to understand past debates as well as current questions.
• Hypothesis testing: framing testable questions, experimental design and statistical analysis are critical in macroevolution and macroecology.

What case studies will be included?

• Case study: Testing hypotheses in time and space: reconstructing the origins of HIV