Download Sympatric Speciation - Fullfrontalanatomy.com

Chapter 14
How Biological Diversity Evolves
PowerPoint® Lectures for
Campbell Essential Biology, Fifth Edition, and
Campbell Essential Biology with Physiology,
Fourth Edition
– Eric J. Simon, Jean L. Dickey, and Jane B. Reece
Lectures by Edward J. Zalisko
© 2013 Pearson Education, Inc.
Biology and Society:
The Sixth Mass Extinction
• Over the past 540 million years, the fossil record
reveals five periods of extinction when 50–90% of
living species suddenly died out.
© 2013 Pearson Education, Inc.
Figure 14.0
Biology and Society:
The Sixth Mass Extinction
• Our current rate of extinction, over the past 400
years, indicates that we may be living in, and
contributing to, the sixth mass extinction period.
• Mass extinctions pave the way for the evolution of
new and diverse forms, but it takes millions of
years for Earth to recover.
© 2013 Pearson Education, Inc.
Figure 14.1
PATTERNS OF EVOLUTION
THE ORIGIN OF SPECIES
• In the 150 years since the publication of Darwin’s
book On the Origin of Species by Means of Natural
Selection, new discoveries and technological
advances have given scientists a wealth of new
information about the evolution of life.
• The diversity of life evolved through speciation,
the process in which one species splits into two or
more species.
© 2013 Pearson Education, Inc.
Figure 14.2
Similarity between different species
Diversity within one species
Reproductive Barriers between Species
• Prezygotic barriers prevent mating or fertilization
between species.
© 2013 Pearson Education, Inc.
Figure 14.3
INDIVIDUALS OF DIFFERENT SPECIES
Prezygotic Barriers
Temporal isolation
Habitat isolation
Behavioral isolation
MATING ATTEMPT
Mechanical isolation
Gametic isolation
FERTILIZATION (ZYGOTE FORMS)
Postzygotic Barriers
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
VIABLE, FERTILE OFFSPRING
No Barriers
Figure 14.4
PREZYGOTIC BARRIERS
Temporal Isolation
Behavioral Isolation
Mechanical Isolation
Habitat Isolation
Gametic Isolation
Reproductive Barriers between Species
• Postzygotic barriers operate if
– interspecies mating occurs and
– hybrid zygotes form.
© 2013 Pearson Education, Inc.
Figure 14.5
POSTZYGOTIC BARRIERS
Reduced Hybrid Viability
Reduced Hybrid Fertility
Horse
Donkey
Mule
Hybrid Breakdown
Mechanisms of Speciation
• A key event in the potential origin of a species
occurs when a population is somehow cut off from
other populations of the parent species.
• Species can form by
– allopatric speciation, due to geographic
isolation, or
– sympatric speciation, without geographic
isolation.
© 2013 Pearson Education, Inc.
Figure 14.6
Allopatric speciation
Sympatric speciation
Allopatric Speciation
• Geologic processes can
– fragment a population into two or more isolated
populations and
– contribute to allopatric speciation.
© 2013 Pearson Education, Inc.
Figure 14.7
Ammospermophilus
harrisii
Ammospermophilus
leucurus
Allopatric Speciation
• Speciation occurs with the evolution of
reproductive barriers between
– the isolated population and
– its parent population.
• Even if the two populations should come back into
contact at some later time, the reproductive
barriers will keep them as separate species.
© 2013 Pearson Education, Inc.
Figure 14.8
Populations
become
allopatric
Populations
become
sympatric
Populations
interbreed
Gene pools merge:
No speciation
Geographic
barrier
Populations
cannot
interbreed
Reproductive
isolation:
Speciation has
occurred
Time
Sympatric Speciation
• Sympatric speciation occurs in populations that live
in the same geographic area.
• An accident during cell division that results in an
extra set of chromosomes is a common route to
sympatric speciation in plants.
• Many polyploid species arise from the hybridization
of two parent species.
© 2013 Pearson Education, Inc.
Sympatric Speciation
• Many domesticated plants are the result of
sympatric speciation, including
– oats,
– potatoes,
– bananas,
– peanuts,
– apples,
– coffee, and
– wheat.
© 2013 Pearson Education, Inc.
What Is the Pace of Speciation?
• There are two contrasting patterns for the pace of
evolution:
1. the gradual pattern, in which big changes
(speciations) occur by the steady accumulation of
many small changes, and
2. the punctuated equilibria pattern, in which there
are
– long periods of little apparent change (equilibria)
interrupted (punctuated) by
– relatively brief periods of rapid change.
© 2013 Pearson Education, Inc.
Figure 14.10
Punctuated
pattern
Time
Gradual
pattern
THE EVOLUTION OF BIOLOGICAL
NOVELTY
• What accounts for the dramatic differences
between dissimilar groups?
© 2013 Pearson Education, Inc.
Adaptation of Old Structures for New Functions
• Birds
– are derived from a lineage of earthbound reptiles
and
– evolved flight from flightless ancestors.
© 2013 Pearson Education, Inc.
Figure 14.11
Wing claw
(like reptile)
Teeth
(like reptile)
Feathers
Long tail with
many vertebrae
(like reptile)
Fossil
Artist’s reconstruction
Adaptation of Old Structures for New Functions
• An exaptation is
– a structure that evolves in one context but
becomes adapted for another function and
– a type of evolutionary remodeling.
• Exaptations can account for the evolution of novel
structures.
© 2013 Pearson Education, Inc.
Adaptation of Old Structures for New Functions
• Bird wings are modified forelimbs that were
previously adapted for non-flight functions, such as
– thermal regulation,
– courtship displays, and/or
– camouflage.
• The first flights may have been only glides or
extended hops as the animal pursued prey or fled
from a predator.
© 2013 Pearson Education, Inc.
Evo-Devo: Development and Evolutionary Novelty
• Evo-devo, evolutionary developmental biology, is
the study of the evolution of developmental
processes in multicellular organisms.
© 2013 Pearson Education, Inc.
Evo-Devo: Development and Evolutionary Novelty
• Homeotic genes are master control genes that
regulate
– the rate,
– timing, and
– spatial pattern of changes in an organism’s form as
it develops from a zygote into an adult.
• Mutations in homeotic genes can profoundly affect
body form.
© 2013 Pearson Education, Inc.
EARTH HISTORY AND MACROEVOLUTION
• Macroevolution is closely tied to the history of
Earth.
© 2013 Pearson Education, Inc.
Geologic Time and the Fossil Record
• The fossil record is
– the sequence in which fossils appear in rock strata
and
– an archive of macroevolution.
© 2013 Pearson Education, Inc.
Figure 14.14
A researcher
excavating a
fossilized
dinosaur
skeleton from
sandstone
A sedimentary fossil formed
by minerals replacing the
organic matter of a tree
A 45-million-year-old
insect embedded
in amber
Trace fossils: footprints, burrows,
or other remnants of an ancient
organism’s behavior
Tusks of a 23,000-year-old mammoth
discovered in Siberian ice
Table 14.1
Table 14.1
The Geologic Time Scale
Geologic
Time
Period
Quaternary
Epoch
Age (millions
of years ago)
Recent
Pleistocene
Pliocene
0.01
1.8
5
Miocene
Cenozoic
era
23
Tertiary
Oligocene
34
Eocene
56
Paleocene
65
Cretaceous
Mesozoic
era
145
Some Important Events in the History of Life
Historical time
Cenozoic
Ice ages; humans appear
Mesozoic
Origin of genus Homo
Continued speciation of mammals and
angiosperms
Paleozoic
Origins of many primate groups,
including apes
Angiosperm dominance increases; origins of most
living mammalian orders
Major speciation of mammals, birds,
and pollinating insects
Flowering plants (angiosperms) appear; many groups of
organisms, including most dinosaur lineages, become
extinct at end of period (Cretaceous extinctions)
Gymnosperms continue as dominant plants;
dinosaurs become dominant
Jurassic
200
Triassic
251
Permian
299
Cone-bearing plants (gymnosperms) dominate landscape;
speciation of dinosaurs, early mammals, and birds
Extinction of many marine and terrestrial organisms
(Permian extinctions); speciation of reptiles; origins of
mammal-like reptiles and most living orders of insects
Extensive forests of vascular plants; first seed
plants; origin of reptiles; amphibians become dominant
Carboniferous
359
Paleozoic
era
Diversification of bony fishes;
first amphibians and insects
Devonian
416
Silurian
Early vascular plants dominate land
444
Ordovician
Cambrian
488
Marine algae are abundant; colonization of land by
diverse fungi, plants, and animals
Origin of most living animal phyla (Cambrian explosion)
542
Precambrian
Relative
Time Span
600
Diverse algae and soft-bodied invertebrate animals appear
635
Oldest animal fossils
2,100
Oldest eukaryotic fossils
2,700
Oxygen begins accumulating in atmosphere
3,500
Oldest fossils known (prokaryotes)
4,600
Approximate time of origin of Earth
Precambrian
Plate Tectonics and Macroevolution
• The continents are not locked in place.
– Continents drift about Earth’s surface on plates of
crust floating on a flexible layer of hot, underlying
material called the mantle.
© 2013 Pearson Education, Inc.
Figure 14.16
Plate Tectonics and Macroevolution
• About 250 million years ago,
– plate movements formed the supercontinent
Pangaea,
– the total amount of shoreline was reduced,
– ocean basins increased in depth,
– sea levels dropped,
– the dry continental interior increased in size, and
– many extinctions occurred.
© 2013 Pearson Education, Inc.
Pangaea is formed.
Mesozoic
Paleozoic
Pangaea splits into
Laurasia and Gondwana.
251 million years ago
135
65
India collides with Eurasia.
Cenozoic
Present
Figure 14.17
Plate Tectonics and Macroevolution
• Plate tectonics helps to explain
– why Mesozoic reptiles in Ghana (West Africa) and
Brazil look so similar and
– how marsupials were free to evolve in isolation in
Australia.
– http://youtu.be/cC8k2Sb1oQ8
© 2013 Pearson Education, Inc.
CLASSIFYING THE DIVERSITY OF LIFE
• Systematics focuses on
– classifying organisms and
– determining their evolutionary relationships.
© 2013 Pearson Education, Inc.
CLASSIFYING THE DIVERSITY OF LIFE
• Taxonomy is the
– identification,
– naming, and
– classification of species.
• Systematics includes taxonomy.
© 2013 Pearson Education, Inc.
Naming Species
• Each species is assigned a two-part Latinized
name or binomial, consisting of
– the genus and
– a name unique for each species.
• The scientific name for humans is Homo sapiens,
– a two part name, italicized,
– given a Latin ending, and
– with the first letter of the genus capitalized.
© 2013 Pearson Education, Inc.
Figure 14.19
Leopard
(Panthera pardus)
Lion
(Panthera leo)
Tiger
(Panthera tigris)
Jaguar (Panthera onca)
Hierarchical Classification
• The taxonomic hierarchy extends to progressively
broader categories of classification, from genus to
– family,
– order,
– class,
– phylum,
– kingdom, and
– domain.
© 2013 Pearson Education, Inc.
Figure 14.20
Leopard
(Panthera pardus)
Species
Panthera
pardus
Genus
Panthera
Family
Felidae
Order
Carnivora
Class
Mammalia
Phylum
Chordata
Kingdom
Animalia
Domain
Eukarya
Classification and Phylogeny
• The goal of systematics is to have classification
reflect evolutionary relationships.
• Biologists use phylogenetic trees to
– depict hypotheses about the evolutionary history of
species and
– reflect the hierarchical classification of groups
nested within more inclusive groups.
© 2013 Pearson Education, Inc.
Figure 14.21
Order
Family
Felidae
Genus
Species
Panthera
Panthera
pardus
(leopard)
Mephitis
Mephitis
mephitis
(striped skunk)
Carnivora
Mustelidae
Lutra
Lutra
lutra
(European
otter)
Canis
latrans
(coyote)
Canidae
Canis
Canis
lupus
(wolf)
Molecular Biology as a Tool in Systematics
• Molecular systematics
– compares nucleotide and amino acid sequences
between organisms and
– can reveal evolutionary relationships.
• The more recently two species have branched
from a common ancestor, the more similar their
nucleotide and amino acid sequences should be.
© 2013 Pearson Education, Inc.
Molecular Biology as a Tool in Systematics
• Some fossils are preserved in such a way that
DNA fragments can be extracted for comparison
with living organisms.
© 2013 Pearson Education, Inc.
Figure 14.22
The Cladistic Revolution
• In cladistics, organisms are grouped by common
ancestry.
• A clade consists of an ancestral species and all its
evolutionary descendants and forms a distinct
branch in the tree of life.
© 2013 Pearson Education, Inc.
Figure 14.23
Iguana
Outgroup
(reptile)
Duck-billed
platypus
Hair, mammary
glands
Kangaroo
Gestation
Beaver
Long gestation
Ingroup
(mammals)
The Cladistic Revolution
• Cladistics has changed the traditional classification
of some organisms, including the relationships
between
– dinosaurs,
– birds,
– crocodiles,
– lizards, and
– snakes.
© 2013 Pearson Education, Inc.
Figure 14.24
Lizards
and snakes
Crocodilians
Pterosaurs
Common
ancestor of
crocodilians,
dinosaurs,
and birds
Ornithischian
dinosaurs
Saurischian
dinosaurs
Birds
Classification: A Work in Progress
• Phylogenetic trees are hypotheses about
evolutionary history.
• Linnaeus divided all known forms of life between
the plant and animal kingdoms.
• This two-kingdom system prevailed in biology for
over 200 years.
© 2013 Pearson Education, Inc.
Classification: A Work in Progress
• In the mid-1900s, the two-kingdom system was
replaced by a five-kingdom system that
– placed all prokaryotes in one kingdom and
– divided the eukaryotes among four other
kingdoms.
© 2013 Pearson Education, Inc.
Classification: A Work in Progress
• In the late 1900s, molecular studies and cladistics
led to the development of a three-domain system,
recognizing
– two domains of prokaryotes (Bacteria and
Archaea) and
– one domain of eukaryotes (Eukarya).
© 2013 Pearson Education, Inc.
http://youtu.be/fQwI90bkJl4