Chapters 10 - Races and Species

Notes for Understanding Evolution - Chapter 10

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General guide on these review questions here

Notes for Chapter 10: Races and Species

Introduction

Key Terms: interbreeding

I. Variation Between Populations

Key Terms: clinal variation

RQUE10.1: For the example of the yarrow plant, Achillea lanulosa, what is the direct evidence that the clinal pattern of variation in plant height, etc., is due to genetic differences between geographically separated populations, not just environmental effects?

II. Races

Key Terms: race (in biology, refers to populations with well-marked discontinuities, sometimes formally recognized as geographic subspecies - see p. 114)

RQUE10.2: What normally maintains differences between geographically separate races, as they are defined by biologists?

III. Formation of Species

Key Terms: species - actually very controversial to define and the differences between species concepts used by different authors are often great - the species definition given on p. 114 is a version of the "biological species concept" (BSC) - this is the most popular species concept in textbooks but has been criticized for a number of reasons (see: 1 - 2 - 3) - another currently popular species concept is the "phylogenetic species concept" (see here for an example of "why it matters" by Joel Cracraft, one of the proposers of the PSC, illustrated with the group he studies, birds of paradise)

RQUE10.3: What are the multiple important components of the model for the process of geographic speciation, as described in Fig. 10.4?

IV. Nomenclature

Key Terms: monotypic vs. polytypic speices

V. Reproductive Isolation Mechanisms

Key Terms: sympatric (vs. parapatric) populations, reproductive isolating mechanisms of two types: prezygotic vs. postzygotic, hybrid inviability, hybrid breakdown

RQUE10.4: Characterize the distinction between pre- and postzygotic isolation mechanisms, using specific examples to distinguish between different types of each.

VI. Origin of Isolation Mechanisms

RQUE10.5: For the case of Vermont and Mexican leopard frogs, what is the evidence (if any) that isolation mechanisms arose under selection for the avoidance of hybrid inviability?

VII. Humans: A Single Variable Species

RQUE10.6: In what ways does a "biological" definition of "race" differ from the way many apply the term in the case of humans?

Click link to return to Biology 409 Schedule
or back to Chapter 9 or ahead to Chapter 11