1. Chapter 14
The Origin of Species

2. Mosquito Mystery Speciation is the emergence of new species
In England and North America
Two species of mosquitoes exist and spread West Nile virus

3. 14.1 The origin of species is the source of biological diversity
Speciation, the origin of new species
Is at the focal point of evolution
Figure 14.1

4. Earth’s incredible biological diversity is the result of macroevolution
Which begins with the origin of new species

5. CONCEPTS OF SPECIES 14.2 What is a species?
Carolus Linnaeus, a Swedish physician and botanist
Used physical characteristics to distinguish species
Developed the binomial system of naming organisms
Linnaeus’ system established the basis for taxonomy
The branch of biology concerned with naming and classifying the diverse forms of life

6. Similarities between some species and variation within a species
Can make defining species difficult
Figure 14.2A
Figure 14.2B

7. The Biological Species Concept
The biological species concept defines a species as
A population or group of populations whose members can interbreed and produce fertile offspring

8. Other Species Concepts
The morphological species concept
Classifies organisms based on observable phenotypic traits
The ecological species concept
Defines a species by its ecological role
The phylogenetic species concept
Defines a species as a set of organisms representing a specific evolutionary lineage

9. 14.3 Reproductive barriers keep species separate
Serve to isolate a species’ gene pool and prevent interbreeding
Are categorized as prezygotic or postzygotic
Table 14.3

10. Prezygotic Barriers Prezygotic barriers
Prevent mating or fertilization between species

11. In temporal isolation Two species breed at different times
Figure 14.3A

12. In behavioral isolation
There is little or no sexual attraction between species, due to specific behaviors
Figure 14.3B

13. In mechanical isolation
Female and male sex organs or gametes are not compatible
Figure 14.3C

14. Postzygotic Barriers Postzygotic barriers
Operate after hybrid zygotes are formed

15. One postzygotic barrier is hybrid sterility
Where hybrid offspring between two species are sterile and therefore cannot mate
Figure 14.3D

16. MECHANISMS OF SPECIATION
14.4 Geographic isolation can lead to speciation
In allopatric speciation
A population is geographically divided, and new species often evolve
A. harrisi
A. leucurus
Figure 14.4

17. population populations
14.5 Reproductive barriers may evolve as populations diverge
Laboratory studies of fruit flies
Have shown that changes in food sources can cause speciation
Initial sample
of fruit flies
Starch medium
Maltose medium
Results of
mating experiments
Female
Same Different
population populations
Female
Starch Maltose 22 9 18 15
Male
Maltose Starch
Male
Different Same 8 20 12 15
Mating frequencies
in experimental group
Mating frequencies
in control group
Figure 14.5A

18. Geographic isolation in Death Valley
Has led to the evolution of new species of pupfish
A pupfish
Figure 14.5B

19. 14.6 New species can also arise within the same geographic area as the parent species
In sympatric speciation
New species may arise without geographic isolation

20. Many plant species have evolved by polyploidy
Multiplication of the chromosome number due to errors in cell division
Parent species
Zygote
Offspring may be viable and self-fertile
Meiotic
error
Self-fertilization
2n = 6
Diploid
4n = 12
Tetraploid
O. lamarckiana
Unreduced
diploid gametes
Figure 14.6A
O. gigas
Figure 14.6B

21. CONNECTION 14.7 Polyploid plants clothe and feed us
Many plants, including food plants such as bread wheat
Are the result of hybridization and polyploidy
When a tetraploid plant pollinates a diploid plant of the parental species, what will be the ploidy of the resulting zygote?  
Triploid AA BB 
Wild Triticum
(14 chromosomes)
Triticum monococcum
(14 chromosomes) AB
Sterile hybrid
(14 chromosomes)
Meiotic error and
self-fertilization
AA BB  DD
T.tauschii
(wild)
(14 chromosomes)
T.turgidum
Emmer wheat
(28 chromosomes)
ABD
Sterile hybrid
(21 chromosomes)
Meiotic error and
self-fertilization
AA BB DD
Figure 14.7A
T.aestivum
Bread wheat
(42 chromosomes)
Figure 14.7B

22. 14.8 Adaptive radiation may occur in new or newly vacated habitats
In adaptive radiation, the evolution of new species
Occurs when mass extinctions or colonization provide organisms with new environments

23. Island chains Provide examples of adaptive radiation
Cactus-seed-eater
(cactus finch) 2 A 1 B B B 3 B C C 4 C C D C D 5 D
Figure 14.8B
Tool-using insect-eater
(woodpecker finch)
Seed-eater
(medium ground finch)
Figure 14.8A

24. 14.9 Peter and Rosemary Grant study the evolution of Darwin’s finches
TALKING ABOUT SCIENCE
14.9 Peter and Rosemary Grant study the evolution of Darwin’s finches
Peter and Rosemary Grant
Have documented natural selection acting on populations of Galápagos finches
Figure 14.9

25. The occasional hybridization of finch species
May also have been important in their adaptive radiation

26. 14.10 The tempo of speciation can appear steady or jumpy
According to the gradualism model
New species evolve by the gradual accumulation of changes brought about by natural selection
Time
Figure 14.10A

27. The punctuated equilibrium model draws on the fossil record
Where species change the most as they arise from an ancestral species and then change relatively little for the rest of their existence
Time
Figure 14.10B

28. Transparent protective
MACROEVOLUTION
14.11 Evolutionary novelties may arise in several ways
Many complex structures evolve in many stages
From simpler versions having the same basic function
Light-sensitive
cells
Light-sensitive
cells
Fluid-filled cavity
Transparent protective
tissue (cornea)
Cornea
Lens
Layer of
light-sensitive
cells (retina)
Eyecup
Retina
Nerve
fibers
Nerve
fibers
Optic
nerve
Optic
nerve
Optic
nerve
Patch of light-
sensitive cells
Simple pinhole
camera-type eye
Eye with
primitive lens
Complex
camera-type eye
Eyecup
Limpet
Abalone
Nautilus
Marine snail
Squid
Figure 14.11

29. Other novel structures result from exaptation
a structure that evolved in one context is later adapted for another function.

30. 14.12 Genes that control development are important in evolution
Many striking evolutionary transformations are the result of a change in the rate or timing of developmental change.
Paedomorphosis is the retention in the adult of features that were juvenile in ancestors
Figure 14.12A

31. Changes in the timing and rate of growth
Have also been important in human evolution
Chimpanzee fetus
Chimpanzee adult
Human fetus
Human adult
Figure 14.12B

32. Stephen Jay Gould, an evolutionary biologist
Contended that Mickey Mouse “evolved”
Copyright Disney
Enterprises, Inc.
Figure 14.12C

33. 14.13 Evolutionary trends do not mean that evolution is goal directed
Evolutionary trends reflect species selection
The unequal speciation or unequal survival of species on a branching evolutionary tree
E RECENT
Equus
Hippidion and other genera
PLEISTOCEN
Nannippus
Pliohippus
Hipparion
Neohipparion
PLIOCENE
Sinohippus
Megahippus
Callippus
Archaeohippus
MIOCENE
Merychippus
Anchitherium
Hypohippus
Parahippus
Miohippus
OLIGOCENE
Mesohippus
Paleotherium
Epihippus
Propalaeotherium
Pachynolophus
Orohippus
EOCENE
Grazers
Browsers
Figure 14.13
Hyracotherium