Download Chapter 25 PowerPoint

Chapter 25
The History of Life on Earth
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Adaptive Radiations
• Adaptive radiation is the evolution of diversely
adapted species from a common ancestor
upon introduction to new environmental
opportunities
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Worldwide Adaptive Radiations
• Mammals underwent an adaptive radiation
after the extinction of terrestrial dinosaurs
• The disappearance of dinosaurs (except birds)
allowed for the expansion of mammals in
diversity and size
• Other notable radiations include photosynthetic
prokaryotes, large predators in the Cambrian,
land plants, insects, and tetrapods
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-17
Adaptive Radiation of Mammals
Ancestral
mammal
Monotremes
(5 species)
ANCESTRAL
CYNODONT
Marsupials
(324 species)
Eutherians
(placental
mammals;
5,010 species)
250
200
100
150
Millions of years ago
50
0
Regional Adaptive Radiations
• Adaptive radiations can occur when organisms
colonize new environments with little
competition
• The Hawaiian Islands are one of the world’s
great showcases of adaptive radiation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-18
Close North American relative,
the tarweed Carlquistia muirii
Dubautia laxa
KAUAI
5.1
million
years
MOLOKAI
OAHU
3.7 LANAI
million
years
1.3
MAUI million
years
Argyroxiphium sandwicense
HAWAII
0.4
million
years
Dubautia waialealae
These plants had a common
ancestor 5 million years ago
Dubautia scabra
Dubautia linearis
Fig. 25-18a
KAUAI
5.1
million
years
MOLOKAI
OAHU
3.7
million
years
1.3
MAUI million
years
LANAI
Pacific Tectonic plate has been moving to the west,
with it the formation of the Hawaiian islands occured
causing variation between the islands' topography and
weather, causing the formation of different environments
and with it different species
HAWAII
0.4
million
years
Concept 25.5: Major changes in body form can result
from changes in the sequences and regulation of
developmental genes
• Studying genetic mechanisms of change can
provide insight into large-scale evolutionary
change
Evolutionary Effects of Development Genes
• Genes that program development control the
rate, timing, and spatial pattern of changes in
an organism’s form as it develops into an adult
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Changes in Rate and Timing
• Heterochrony is an evolutionary change in the
rate or timing of developmental events
• It can have a significant impact on body shape
• The contrasting shapes of human and
chimpanzee skulls are the result of small
changes in relative growth rates
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-19
Heterochrony
Arms and legs grow
faster than head and
trunk parts of body
Newborn
2
5
Age (years)
15
Adult
(a) Differential growth rates in a human
skuls of human and
chimp are similar at
the fetus stage, but
become much different once adults
Chimpanzee fetus
Chimpanzee adult
Human fetus
Human adult
(b) Comparison of chimpanzee and human skull growth
• In paedomorphosis, the rate of reproductive
development accelerates compared with
somatic development
• The sexually mature species may retain body
features that were juvenile structures in an
ancestral species
fish-like tail
gills
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Changes in Spatial Pattern
• Substantial evolutionary change can also result
from alterations in genes that control the
location/placement and organization of body
parts
• Homeotic genes determine such basic
features as where wings and legs will develop
on a bird or how a flower’s parts are arranged
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Hox genes are a class of homeotic genes that
provide positional information during
development
• If Hox genes are expressed in the wrong
location, body parts can be produced in the
wrong location
• For example, in crustaceans, a swimming
appendage can be produced instead of a
feeding appendage
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Evolution of vertebrates from invertebrate
animals was associated with alterations in Hox
genes
• Two duplications of Hox genes have occurred
in the vertebrate lineage
• These duplications may have been important in
the evolution of new vertebrate characteristics
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-21
Hypothetical vertebrate
ancestor (invertebrate)
with a single Hox cluster
First Hox
duplication
Hypothetical early
vertebrates (jawless)
with two Hox clusters
Second Hox
duplication
Vertebrates (with jaws)
with four Hox clusters
The Evolution of Development
• The tremendous increase in diversity during
the Cambrian explosion is a puzzle
• Developmental genes may play an especially
important role
• Changes in developmental genes can result in
new morphological forms
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Changes in Genes
• New morphological forms likely come from
gene duplication events that produce new
developmental genes
• A possible mechanism for the evolution of sixlegged insects from a many-legged crustacean
ancestor has been demonstrated in lab
experiments
• Specific changes in the Ubx gene have been
identified that can “turn off” leg development
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-22
Hox gene 6
Hox gene 7
Hox gene 8
Ubx
About 400 mya
Drosophila
Artemia
Changes in Gene Regulation
• Changes in the form of organisms may be
caused more often by changes in the
regulation of developmental genes instead of
changes in their sequence
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Concept 25.6: Evolution is not goal oriented
• Evolution is like tinkering—it is a process in
which new forms arise by the slight
modification of existing forms
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Evolutionary Novelties
• Most novel biological structures evolve in many
stages from previously existing structures
• Complex eyes have evolved from simple
photosensitive cells independently many times
• Exaptations are structures that evolve in one
context but become co-opted for a different
function
• Natural selection can only improve a structure
in the context of its current utility
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-24
Pigmented
cells
Pigmented cells
(photoreceptors)
Epithelium
slit shell
Limpet
Nerve fibers
upload.wikimedia.org
(a) Patch of pigmented cells
Fluid-filled cavity
Epithelium
Nautilus
www.dkimages.com
Nerve fibers
upload.wikimedia.org
(b) Eyecup
Cellular
mass
(lens)
Cornea
Murex
Optic
nerve
Pigmented
layer (retina)
(c) Pinhole camera-type eye
Optic nerve
(d) Eye with primitive lens
upload.wikimedia.org
Cornea
Lens
Retina
Optic nerve
(e) Complex camera-type eye
Loligo gahi
www.teppitak.com
Evolutionary Trends
• Extracting a single evolutionary progression
from the fossil record can be misleading
• Apparent trends should be examined in a
broader context
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 25-25
Recent
(11,500 ya)
Equus
Pleistocene
(1.8 mya)
Hippidion and other genera
Nannippus
Pliohippus
Pliocene
(5.3 mya)
Hipparion Neohipparion
Sinohippus
Megahippus
Callippus
Archaeohippus
Miocene
(23 mya)
Merychippus
Hypohippus
Anchitherium
Parahippus
Miohippus
Oligocene
(33.9 mya)
Mesohippus
Paleotherium
Epihippus
Propalaeotherium
Eocene
(55.8 mya)
Pachynolophus
Orohippus
Key
Hyracotherium
The End
Grazers
Browsers