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Origin of SpeciesOrigin of Species
Ch. 14Ch. 14
Pre-AP BiologyPre-AP Biology
Ms. HautMs. Haut
The origin of species is the The origin of species is the source of biological diversitysource of biological diversity SpeciationSpeciation, the origin of new species, the origin of new species
Is at the focal point of evolutionIs at the focal point of evolution
Figure 14.1
CONCEPTS OF SPECIESCONCEPTS OF SPECIES
What is a species?What is a species? Carolus Linnaeus, a Swedish physician and Carolus Linnaeus, a Swedish physician and
botanistbotanist Used physical characteristics to distinguish speciesUsed physical characteristics to distinguish species Developed the binomial system of naming organismsDeveloped the binomial system of naming organisms
Linnaeus’ system established the basis for Linnaeus’ system established the basis for taxonomytaxonomy The branch of biology concerned with naming and The branch of biology concerned with naming and
classifying the diverse forms of lifeclassifying the diverse forms of life
SpeciesSpecies
Similarities Similarities between some between some species and species and variation within a variation within a speciesspecies Can make defining Can make defining
species difficultspecies difficult
Figure 14.2B
Figure 14.2A
What is a species?What is a species?
The Biological Species ConceptThe Biological Species Concept The biological species concept defines a The biological species concept defines a
species asspecies as A population or group of populations whose A population or group of populations whose
members can interbreed and produce fertile members can interbreed and produce fertile offspringoffspring
Reproductively isolated by various factors Reproductively isolated by various factors preventing mixing with other speciespreventing mixing with other species
Reproductive barriers Reproductive barriers keep species separatekeep species separate
Reproductive Reproductive barriersbarriers Serve to isolate Serve to isolate
a species’ gene a species’ gene pool and pool and prevent prevent interbreedinginterbreeding
Are categorized Are categorized as prezygotic or as prezygotic or postzygoticpostzygoticTable 14.3
Prevent mating or fertilization between Prevent mating or fertilization between speciesspecies Habitat isolationHabitat isolation —species live in same general —species live in same general
area but not the same placesarea but not the same places Behavioral isolationBehavioral isolation —special signals recognized —special signals recognized Temporal isolationTemporal isolation —breeding occurs at different —breeding occurs at different
timestimes Mechanical isolationMechanical isolation —anatomically incompatible —anatomically incompatible Gametic isolationGametic isolation —gamete recognition —gamete recognition
Prezygotic BarriersPrezygotic Barriers
Two species breed at different timesTwo species breed at different times
Figure 14.3A
Temporal isolationTemporal isolation
There is little or no sexual attraction There is little or no sexual attraction between species, due to specific between species, due to specific behaviorsbehaviors
Figure 14.3B
Behavioral isolationBehavioral isolation
Figure 14.3C
Female and male sex organs or gametes Female and male sex organs or gametes are not compatibleare not compatible
Mechanical isolationMechanical isolation
Operate after hybrid zygotes are formedOperate after hybrid zygotes are formedPrevent the hybrid zygote from Prevent the hybrid zygote from developing into a viable, fertile adultdeveloping into a viable, fertile adult Reduced hybrid viabilityReduced hybrid viability —embryo —embryo
abortedaborted Reduced hybrid fertilityReduced hybrid fertility —offspring sterile —offspring sterile Hybrid breakdownHybrid breakdown —offspring of hybrids —offspring of hybrids
sterilesterile
Postzygotic BarriersPostzygotic Barriers
Figure 14.3D
Offspring between two species are Offspring between two species are sterile and therefore cannot matesterile and therefore cannot mate
Hybrid sterilityHybrid sterility
MECHANISMS OF MECHANISMS OF SPECIATIONSPECIATION
Geographic isolation can lead to Geographic isolation can lead to speciationspeciation In In allopatric speciationallopatric speciation
A population is geographically A population is geographically divided, and new species often evolvedivided, and new species often evolve
A. harrisi A. leucurus
Figure 14.4
Figure 14.9
Laboratory studies of fruit flies Laboratory studies of fruit flies Have shown that changes in food Have shown that changes in food
sources can cause speciationsources can cause speciation
Figure 14.5A
Starch medium Maltose medium
Initial sampleof fruit flies
Results ofmating experiments
Female Starch Maltose
Female Same Different
population populations
Mal
e M
alto
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tarc
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Mal
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iffer
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ame
Mating frequenciesin experimental group
Mating frequenciesin control group
22 9
208 12
18 15
15
Reproductive barriers may Reproductive barriers may evolve as populations evolve as populations
divergediverge
Geographic isolation in Death Geographic isolation in Death ValleyValleyHas led to the evolution of new Has led to the evolution of new species of pupfishspecies of pupfish
Figure 14.5B A pupfish
Allopatric SpeciationAllopatric Speciation
http://faculty.uca.edu/~benw/biol4402/lecture3/sld005.htm
http://faculty.uca.edu/~benw/biol4402/lecture3/sld005.htm
Male pupfish
Pupfish: Example of Speciation
http://members.aol.com/OptiquesJN/death.htm
http://faculty.uca.edu/~benw/biol4402/lecture3/sld005.htm
http://faculty.uca.edu/~benw/biol4402/lecture3/sld005.htm
http://faculty.uca.edu/~benw/biol4402/lecture3/sld005.htm
MECHANISMS OF MECHANISMS OF SPECIATIONSPECIATION
New species can also arise within New species can also arise within the same geographic area as the the same geographic area as the parent speciesparent species In In sympatric speciationsympatric speciation
New species may arise without New species may arise without geographic isolationgeographic isolation
Many plant species have evolved by Many plant species have evolved by polyploidypolyploidy Multiplication of the chromosome Multiplication of the chromosome
number due to errors in cell division number due to errors in cell division Results in extra sets of chromosomesResults in extra sets of chromosomes
Figure 14.6B
Parent species
Meioticerror
Self-fertilization
Offspring may be viable and self-fertile
Zygote
Unreduced diploid gametes
2n = 6Diploid
4n = 12Tetraploid
O. gigas
O. lamarckiana
Figure 14.6A
Sympatric SpeciationSympatric Speciation
A Shetland pony on a UK farm has surprised its owners by giving birth to a half-zebra foal.
Horse—2n=46Zebra—2n=44
In In adaptive radiationadaptive radiation, the evolution of , the evolution of new species new species Occurs when mass extinctions or colonization Occurs when mass extinctions or colonization
provide organisms with new environmentsprovide organisms with new environments Island chainsIsland chains
Provide examples of adaptive radiationProvide examples of adaptive radiation
Adaptive radiation may Adaptive radiation may occur in new or newly occur in new or newly
vacated habitatsvacated habitats
Cactus-seed-eater(cactus finch)
Seed-eater(medium ground finch)
Tool-using insect-eater(woodpecker finch) Figure 14.8B
12
3
4
5
A B
B
B
C C
C
B
C C D
D
D
Figure 14.8A
TALKING ABOUT TALKING ABOUT SCIENCESCIENCE
Peter and Rosemary Grant study the Peter and Rosemary Grant study the evolution of Darwin’s finchesevolution of Darwin’s finches Peter and Rosemary GrantPeter and Rosemary Grant
Have documented natural selection acting Have documented natural selection acting on populations of Galápagos fincheson populations of Galápagos finches
Figure 14.9
1. Seeds blown over from mainland and form small colony
2. Gene pool isolated—evolves into new species B
3. Storms/other agents blow seeds to nearby island and evolve into species C
4. Some of species C recolonize the first island and cohabit with species B and some populate a new island
5. Speciation continues between new areas and previously colonized areas
Plant Plant speciationspeciation
Figure 14.12a
The tempo of speciation The tempo of speciation can appear steady or can appear steady or
jumpyjumpy According to the According to the
gradualism modelgradualism modelNew species New species evolve by the evolve by the gradual gradual accumulation accumulation of changes of changes brought about brought about by natural by natural selectionselection
Figure 14.12b
The tempo of speciation The tempo of speciation can appear steady or can appear steady or
jumpyjumpy The The punctuated punctuated
equilibrium modelequilibrium model draws on the fossil draws on the fossil recordrecord Species diverge Species diverge
in spurts of in spurts of relatively rapid relatively rapid change, instead change, instead of slowly and of slowly and graduallygradually
Evolutionary trends do not Evolutionary trends do not mean that evolution is goal mean that evolution is goal
directeddirected Evolutionary trends Evolutionary trends
reflect species reflect species selectionselection The unequal The unequal
speciation or speciation or unequal unequal survival of survival of species on a species on a branching branching evolutionary evolutionary treetree Figure 14.13
Hippidion and other genera
Nannippus
NeohipparionHipparion
Sinohippus Megahippus
Archaeohippus
Callippus
HypohippusAnchitherium
Miohippus
Parahippus
Paleotherium
Propalaeotherium
Pachynolophus Orohippus
Epihippus
Equus
Pliohippus
Merychippus
Mesohippus
HyracotheriumGrazersBrowsers
EO
CE
NE
OL
IGO
CE
NE
MIO
CE
NE
PL
IOC
EN
EE
RE
CE
NT
PL
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Hippidion and other genera
Nannippus
NeohipparionHipparion
Sinohippus Megahippus
Archaeohippus
Callippus
HypohippusAnchitherium
Miohippus
Parahippus
Paleotherium
Propalaeotherium
Pachynolophus Orohippus
Epihippus
Equus
Pliohippus
Merychippus
Mesohippus
HyracotheriumGrazersBrowsers
Hippidion and other genera
Nannippus
NeohipparionHipparion
Sinohippus Megahippus
Archaeohippus
Callippus
HypohippusAnchitherium
Miohippus
Parahippus
Paleotherium
Propalaeotherium
Pachynolophus Orohippus
Epihippus
Equus
Pliohippus
Merychippus
Mesohippus
HyracotheriumGrazersBrowsers
EO
CE
NE
OL
IGO
CE
NE
MIO
CE
NE
PL
IOC
EN
EE
RE
CE
NT
PL
EIS
TO
CE
N
Earth History and Earth History and MacroevolutionMacroevolution
MacroevolutionMacroevolution Is closely tied to Is closely tied to
the history of the the history of the Earth.Earth.
The fossil recordThe fossil record Is an archive of Is an archive of
macroevolution.macroevolution.
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FossilizationFossilization Most fossils are actually casts of animals or plants. Most fossils are actually casts of animals or plants. Animal dies and sinks to the sea floor. Animal dies and sinks to the sea floor. Tissue begins to decay and is buried under layers of Tissue begins to decay and is buried under layers of
sediment such as mud or sand. sediment such as mud or sand. These layers become rock. These layers become rock. The hard parts of the animal are The hard parts of the animal are
replaced with minerals such as replaced with minerals such as iron iron pyrites or silica. pyrites or silica.
These minerals form the fossil. These minerals form the fossil. Usually fossils show the hard parts of Usually fossils show the hard parts of
the animal or plant - such as the animal or plant - such as shell or bones.shell or bones.
Trace fossilsTrace fossils——evidence of living evidence of living plants or animals, such as worm plants or animals, such as worm burrows or dinosaur footprints. burrows or dinosaur footprints.
Most fossils are found in Most fossils are found in sedimentary rocks - rocks which sedimentary rocks - rocks which were created when shells or small were created when shells or small loose bits of rock are laid down in loose bits of rock are laid down in layers (limestone, sandstone, clay layers (limestone, sandstone, clay and chalk)and chalk)
http://stevekluge.com/geoscience/images/trackwayd.jpghttp://science.kennesaw.edu/~jdirnber/Bio2108/Lecture/LecBiodiversity/Tracehelminth.jpg
Determining Age of Determining Age of FossilsFossils
Relative ageRelative age—determined by position —determined by position in sedimentary rockin sedimentary rock
Absolute ageAbsolute age—determined by —determined by radiometric dating (radioactive radiometric dating (radioactive isotopes)isotopes) Based on Based on half-lifehalf-life of an isotope—period of an isotope—period
it takes for half the radioactive material it takes for half the radioactive material to decayto decay
http://evolution.berkeley.edu/evosite/lines/images/strat_column.gif
Carbon-14Carbon-14
3.135
6.254
12.53
252
501
1000
C-14 Remaining(atoms)
Number of Half-Life
3.135
6.254
12.53
252
501
1000
C-14 Remaining(atoms)
Number of Half-Life Half-Life of Carbon 14
0
20
40
60
80
100
120
1 2 3 4 5 6
Number of Half-Life
Nu
mb
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f A
tom
s o
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-14
Figure 14.17a
Plate Tectonics and Plate Tectonics and MacroevolutionMacroevolution
The continents are not The continents are not locked in place.locked in place. They drift about Earth’s They drift about Earth’s
surface on plates of crust surface on plates of crust floating on a flexible floating on a flexible layer called the mantle.layer called the mantle.
California’s infamous San California’s infamous San Andreas faultAndreas fault Is at a border where two Is at a border where two
plates slide past each plates slide past each other.other.
Figure 14.18
Plate TectonicsPlate Tectonics About 250 million years agoAbout 250 million years ago
Plate movements formed Plate movements formed the supercontinent the supercontinent Pangaea.Pangaea.
Many extinctions Many extinctions occurred, allowing occurred, allowing survivors to diversify.survivors to diversify.
About 180 million years agoAbout 180 million years ago Pangaea began to break Pangaea began to break
up, causing geographic up, causing geographic isolation.isolation.
Figure 14.19
Mass Extinctions and Mass Extinctions and Explosive Explosive
Diversifications of LifeDiversifications of Life The fossil record reveals an episodic history,The fossil record reveals an episodic history,
With long, relatively stable periods punctuated by briefer With long, relatively stable periods punctuated by briefer intervals when the turnover in species composition was intervals when the turnover in species composition was much more extensive.much more extensive.
Extinction is inevitable in a changing world and occurs all Extinction is inevitable in a changing world and occurs all the time.the time. However, extinction rates have not been steady.However, extinction rates have not been steady.
Extinctions typically eliminate various species of organismsExtinctions typically eliminate various species of organisms And are followed by explosive diversifications of And are followed by explosive diversifications of
organisms.organisms.
The Process of Science: The Process of Science: Did a Meteor Kill the Did a Meteor Kill the
Dinosaurs?Dinosaurs? Scientists believe Scientists believe
that about 65 that about 65 million years ago, million years ago, at the end of the at the end of the Cretaceous period,Cretaceous period, A meteor impact A meteor impact
contributed to the contributed to the extinction of the extinction of the dinosaurs.dinosaurs.
Figure 14.20
AcknowledgementsAcknowledgements BIOLOGY: CONCEPTS AND CONNECTIONSBIOLOGY: CONCEPTS AND CONNECTIONS 5th 5th
Edition, by Campbell, Reece, Mitchell, and Taylor, Edition, by Campbell, Reece, Mitchell, and Taylor, ©2006. These images have been produced from the ©2006. These images have been produced from the originals by permission of the publisher. These originals by permission of the publisher. These illustrations may not be reproduced in any format for illustrations may not be reproduced in any format for any purpose without express written permission any purpose without express written permission from the publisher.from the publisher.
Unless otherwise noted, illustrations are credited to Unless otherwise noted, illustrations are credited to Pearson Education which have been borrowed from Pearson Education which have been borrowed from BIOLOGY: CONCEPTS AND CONNECTIONSBIOLOGY: CONCEPTS AND CONNECTIONS 3rd 3rd Edition, by Campbell, Reece, Mitchell, and Taylor, Edition, by Campbell, Reece, Mitchell, and Taylor, ©2000. These images have been produced from the ©2000. These images have been produced from the originals by permission of the publisher. These originals by permission of the publisher. These illustrations may not be reproduced in any format for illustrations may not be reproduced in any format for any purpose without express written permission any purpose without express written permission from the publisher.from the publisher.