Copyright © 2013 Pearson Education, Inc. All rights reserved. Exploring Biological Anthropology: The Essentials, 3 rd Edition CRAIG STANFORD JOHN S. ALLEN SUSAN C. ANTÓN
Copyright © 2013 Pearson Education, Inc. All rights reserved. Chapter 5 The Forces of Evolution And The Formation of Species
Copyright © 2013 Pearson Education, Inc. All rights reserved. How Evolution Works Where Does Variation Come From? – Mutations Point mutation Chromosomal mutation
Copyright © 2013 Pearson Education, Inc. All rights reserved. How Evolution Works (cont’d) How Natural Selection Works – Phenotypes in environments – Changes in gene frequencies – Directional Selection/ Stabilizing Selection
Copyright © 2013 Pearson Education, Inc. All rights reserved. How Evolution Works (cont’d) Other Ways By Which Evolution Happens – Gene Flow: movement of genes between populations – Genetic Drift: random changes in gene frequency in a population – Founder Effect: genetic bottleneck – Sexual Selection: Differential reproductive success within one sex of any species
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution Taxonomy and Speciation – Systematics: branch of biology that describes organismal variation (what used to be called taxonomy) – Homology: the notion that similar features in two related organisms look alike because of a shared evolutionary history Convergent (parallel) evolution – Cladistics Cladograms – Phenetics: numerical taxonomy
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) What is a Species? An interbreeding group of animals or plants that are reproductively isolated through anatomy, ecology, behavior, or geographic distribution from all other such groups (Mayr, 1942) – Biological species concept – Evolutionary species concept – Ecological species concept – Recognition species concept
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) Species Concepts Biological species concept Evolutionary species concept Ecological species concept Recognition species concept
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) Reproductive Isolating Mechanisms (RIMs) – Any factor that prevents a male and female of two different species from hybridizing Premating RIMs Postmating RIMs
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) Premating RIMs Habitat isolation Temporal isolation Behavioral isolation Mechanical incompatibility Postmating RIMs Sperm-egg incompatibility Zygote inviability Embryonic or fetal inviability Offspring inviability Offspring sterility
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) The Origin of Species: how species are formed – Anagenesis – Cladogenesis – Allopatric speciation – Parapatric speciation – Sympatric speciation
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) The Tempo of Speciation – Gradualism Darwinian Gaps? Macroevolution – Punctuated equilibrium
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) Adaptation Adaptations are evolved phenotypic traits that increase an organism’s reproductive success
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) Adaptations are evolved phenotypic traits that increase an organism’s reproductive success adaptionismreductionism Is Everything Adaptive?
Copyright © 2013 Pearson Education, Inc. All rights reserved. Classification and Evolution (cont’d) (p + q) 2 = p 2 + 2pq + q 2 = 1 Hardy-Weinberg Equilibrium
Copyright © 2013 Pearson Education, Inc. All rights reserved. Levels of Selection Group selection Inclusive Fitness – Behavioral ecology Kin selection Coefficient of relatedness rb > c – Hamilton’s Rule