II homology

Morphology and homology: 

Morphology and homology 22

Key Concepts:: 

Key Concepts: Anatomical comparisons help reconstruct patterns of change through time Biochemical comparisons also provide evidence of macroevolution Diversity characterizes the distribution of species through time Taxonomy is concerned with identifying and naming new species

Slide3: 

Fig. 20.2, p. 312

Examples of natural selection provide evidence of evolution: 

Examples of natural selection provide evidence of evolution Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Insecticides are poisons that kill insects that are pests in crops, swamps, backyards, and homes. The evolution of resistance to insecticides in hundreds of insect species is a classic example of natural selection in action. The results of an application of a new insecticide are typically encouraging, killing 99% of the insects. However, the effectiveness of the insecticide becomes less effective in subsequent applications.

Slide5: 

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings The few survivors from the early applications of the insecticide are those insects with genes that enable them to resist the chemical attack. Only these resistant individuals reproduce, passing on their resistance to their offspring. In each generation the percentage of insecticide-resistant individuals increases.

Slide6: 

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 22.12

Slide7: 

In descent with modification, new species descend from ancestral species by the accumulation of modifications as populations adapt to new environments. The novel features that characterize a new species are not entirely new, but are altered versions of ancestral features. Similarity in characteristics resulting from common ancestry is known as homology. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Slide8: 

Descent with modification is indeed evident in anatomical similarities between species grouped in the same taxonomic category. For example, the forelimbs of human, cats, whales, and bats share the same skeletal elements, but different functions because they diverged from the ancestral tetrapod forelimb. They are homologous structures. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 22.14

Homologous Structures: 

Homologous Structures Vertebrate forelimbs

Slide10: 

Some of the most interesting homologous structures are vestigial organs, structures that have marginal, if any, importance to a current organism, but which had important functions in ancestors. For example, the skeletons of some snakes and of fossil whales retain vestiges of the pelvis and leg bones of walking ancestors. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Slide11: 

Sometimes, homologies that are not obvious in adult organisms become evident when we look at embryonic development. For example, all vertebrate embryos have structures called pharyngeal pouches in their throat at some stage in their development. These embryonic structures develop into very different, but still homologous, adult structures, such as the gills of fish or the Eustacean tubes that connect the middle ear with the throat in mammals. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Comparative Embryology: 

Comparative Embryology Early vertebrate embryos strongly resemble one another Same plan of development

Comparative Morphology: 

Comparative Morphology Homology Similarity in body parts in different organisms Attributable to descent from a common ancestor Analogy Similarity in body parts in different organisms Attributable to similar environmental pressures

Slide14: 

Fig. 20.5, p. 315 jawless fishes land-dwelling stem reptiles class Chondrichthyes (cartilaginous fishes) class Reptilia (reptiles) class Aves (birds) class Mammalia (mammals) shark penguin porpoise pectoral fin flipper (derived from a wing) flipper (derived from a foreleg)

Slide15: 

The geographical distribution of species -- biogeography -- first suggested evolution to Darwin. Species tend to be more closely related to other species from the same area than to other species with the same way of life, but living in different areas. For example, even though some marsupial mammals (those that complete their development in an external pouch) of Australia have look-alikes among the eutherian mammals (those that complete their development in the uterus) that live on other continents, all the marsupial mammals are still more closely related to each other than they are to any eutherian mammal. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Slide16: 

For example, while the sugar glider and flying squirrel have adapted to the same mode of life, they are not closely related. Instead, the sugar glider from Australia is more closely related to other marsupial mammals from Australia than to the flying squirrel, a placental mammal from North America. The resemblance between them is an example of convergent evolution. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 22.15

Slide17: 

In island chains, or archipelagos, individual islands may have different, but related, species --the first mainland invaders reached one island and then evolved into several new species as they colonized other islands in the archipelago. Several well-investigated examples of this phenomenon include the diversification of finches on the Galapagos Islands and fruit flies (Drosophila) on the Hawaiian Archipelago. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Slide18: 

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 22.16 All of the 500 or so endemic species of Drosophila in the Hawaiian archipelago descended from a common ancestor that reached Kauai over 5 million years ago.

Slide19: 

The succession of fossil forms is compatible with what is known from other types of evidence about the major branches of descent in the tree of life. For example, fossil fishes predate all other vertebrates, with amphibians next, followed by reptiles, then mammals and birds. This is consistent with the history of vertebrate descent as revealed by many other types of evidence. In contrast, the idea that all species were individually created at about the same time predicts that all vertebrate classes would make their first appearance in the fossil record in rocks of the same age. This is not what paleontologists actually observe. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Slide20: 

The Darwinian view of life also predicts that evolutionary transitions should leave signs in the fossil record. For example, a series of fossils documents the changes in skull shape and size that occurred as mammals evolved from reptiles. Recent discoveries include fossilized whales that link these aquatic mammals to their terrestrial ancestors. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 22.17

Evidence from Comparative Biochemistry: 

Evidence from Comparative Biochemistry Molecular clocks Neutral mutations Protein comparisons Cytochrome C Nucleic Acid comparisons Base-pairing of DNA or RNA from one species to another

Slide22: 

Fig. 20.9, p. 318-19

Slide23: 

Fig. 20.13, p. 322-23 GREEN PYTHON NILE CROCODILE SEA TURTLE CHAMELEON DINOSAURS OWL

Slide24: 

Fig. 20.14, p. 324 Lamprey Turtle Cat Gorilla Lungfish Trout Human

How Many Kingdoms?: 

How Many Kingdoms? Whittaker’s Five-Kingdom Scheme Monera Protista Fungi Plantae Animalia

Six Kingdom Scheme: 

Six Kingdom Scheme Carl Woese Includes the Archaebacteria