Transcript a18 HowBiodiversity

How Biological Diversity Evolves
CHAPTER 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 Evolves
CHAPTER 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
Reproductive Barriers between Species
Giraffe Courtship Ritual
Albatross Courtship Ritual
Blue-Footed Boobies
Courtship Ritual
How Biological Diversity Evolves
CHAPTER 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
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 Overview
Grand Canyon
What Is the Tempo of Speciation?
•
Traditional evolutionary trees diagram the descent of species as
gradual divergence. Stephen Jay Gould and Nils Elridge
How Biological Diversity Evolves
CHAPTER 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
The Evolution of Biological Novelty
• What accounts for the evolution of biological
novelty?
– Adaptation of old structures
for new functions
– Exaptation
Reptilian scales  feathers
• 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.
Legs  mouthparts
How Biological Diversity Evolves
CHAPTER 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
Earth History and Macroevolution
•
Macroevolution
–
Is closely tied to the history of the Earth.
–
The fossil record is an archive of macroevolution
Macroevolution
Geologic Record or Time Scale
The age of
organisms found in
fossils can be
determined by
radiometric (C-14)
dating
Table 14.1
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.
Lava Flow
Volcanic Eruption
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.
How Biological Diversity Evolves
CHAPTER 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
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
The Taxonomic Hierarchy
Figure 14.21
Classification of the Blackburnian warbler
Domain
Eukarya
(Complex cell organisms)
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.
Three Domain System Evolved From Molecular Systematics Discoveries
Figure 14.26
How Biological Diversity Evolves
CHAPTER 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