How Biological Diversity Evolves CHAPTER 14 Macroevolution and New Species Species Definition Reproductive Barriers Allopatric vs. Sympatric Mechanisms

How Biological Diversity EvolvesCHAPTER 14How Biological Diversity EvolvesCHAPTER 14

•Macroevolution and New Species• Species Definition

• Reproductive Barriers

• Allopatric vs. Sympatric Mechanisms

•The Development of Evolutionary Novelties

•Macroevolution and Earth History

•Taxonomy and Classification• Current System

• Evolutionary Relatedness and Distinct Lineages

Macroevolution and the Diversity of Life

• Macroevolution

– Encompasses the major biological changes evident in the fossil record.

– Includes the formation of new species.

• Speciation

– Is the focal point of macroevolution.

– May occur based on two contrasting patterns.

• In non-branching evolution, a population transforms but does not create a new species.

• In branching evolution, one or more new species branch from a parent species that may continue to exist.

The Origin of Species

• Species is a Latin word meaning “kind” or “appearance.”

• The biological species concept defines a species as

– A population or group of populations whose members have the potential to interbreed and produce fertile offspring.

• The biological species concept cannot be applied in all situations, for example, with fossils and asexual organisms.

Species Similarity and Differences

How Biological Diversity EvolvesCHAPTER 14How Biological Diversity EvolvesCHAPTER 14•Macroevolution and New Species

• Species Definition





•Taxonomy and Classification•Current System

•Evolutionary Relatedness and Distinct Lineages

Reproductive Barriers between Species

Blue-Footed Boobies Courtship Ritual

Giraffe Courtship Ritual

Albatross Courtship Ritual

How Biological Diversity EvolvesCHAPTER 14How Biological Diversity EvolvesCHAPTER 14•Macroevolution and New Species

• Species Definition







Mechanisms of Speciation

• A key event in the potential origin of a species occurs when a population is somehow severed from other populations of the parent species.

Galápagos Islands OverviewGrand Canyon

What Is the Tempo of Speciation?

• Traditional evolutionary trees diagram the descent of species as gradual divergence. Stephen Jay Gould and Nils Elridge









The Evolution of Biological Novelty

• What accounts for the evolution of biological novelty?

– Exaptation

• Structures that evolve in one context gradually becoming adapted for other functions.

• Is a mechanism for novel features to arise gradually through a series of intermediate stages.

– Adaptation of old structures for new functions

Reptilian scales feathers

Legs mouthparts









Earth History and Macroevolution

• Macroevolution

– Is closely tied to the history of the Earth.

– The fossil record is an archive of macroevolution

Macroevolution

Table 14.1

Geologic Record or Time Scale

The age of organisms found in

fossils can be determined by

radiometric (C-14) dating

Plate Tectonics and Macroevolution

• The continents are not locked in place.

– They drift about Earth’s surface on plates of crust floating on a flexible layer called the mantle.

• California’s infamous San Andreas fault

– Is at a border where two plates slide past each other.

• About 250 million years ago

– Plate movements formed the supercontinent Pangaea.

– Many extinctions occurred, allowing survivors to diversify.

Volcanic EruptionLava Flow

Mass Extinctions and Explosive Diversifications of Life

• The fossil record reveals an episodic history,

– With long, relatively stable periods punctuated by briefer intervals when the turnover in species composition was much more extensive.

• Extinction is inevitable in a changing world and occurs all the time.

– However, extinction rates have not been steady.

• Extinctions typically eliminate various species of organisms

– And are followed by explosive diversifications of organisms.









Classifying the Diversity of Life

• Systematics

– Is the study of the diversity and relationships of organisms, both past and present.

• Taxonomy

– Is the identification, naming, and classification of species.

• Carolus Linnaeus

– Developed the formal naming system used today.

– Developed the system of binomial nomenclature

Figure 14.21

The Taxonomic Hierarchy

Domain Eukarya (Complex cell organisms)

Classification of the Blackburnian warbler

Classification and Phylogeny

• The goal of classification is to reflect phylogeny, the evolutionary history of a species.

Sorting Homology from Analogy

• Homologous structures

– Are one of the best sources of information about phylogenetic relationships.

• Convergent evolution

– Involves superficially similar structures in unrelated organisms based on natural selection.

• Analogy

– Is similarity due to convergence.

Molecular Biology as a Tool in Systematics

• Molecular systematics

– Compares DNA and amino acid sequences between organisms.

– Can reveal evolutionary relationships.

• Cladistics

– Is the scientific search for clades, distinctive branches in the history of life

– Uses evolutionary novelties as landmarks for new clades

• Cladistics

– Has changed traditional classification of some organisms.

Figure 14.26

Three Domain System Evolved From Molecular Systematics Discoveries







•Taxonomy and Classification• Current System

• Evolutionary Relatedness and Distinct Lineages

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How Biological Diversity Evolves CHAPTER 14 Macroevolution and New Species Species Definition Reproductive Barriers Allopatric vs. Sympatric Mechanisms