CH 24 PPT the Origin of Species

8/9/2019 CH 24 PPT the Origin of Species

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THE NATURE OF

SPECIES AND THE BIOLOGICAL

SPECIES CONCEPT


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The Biological Species

Concept The biological species concept states that a

species is a grop o! poplations "hose #e#$ersha%e the potential to inter$ree& in natre an&

pro&ce %ia$le' !ertile o!!spring( the) &o not $ree&sccess!ll) "ith other poplations

Formulated by ERNST MAYR,

an evolutionary biologist (194!

Gene flow $et"een poplations hol&s thephenot)pe o! a poplation together


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(a) Similarity between different species

(b) Diversity within a species


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Reproductive Isolation

Reproductive isolation is the e*istence o!

$iological !actors +$arriers, that i#pe&e t"ospecies !ro# pro&cing %ia$le' !ertile o!!spring

Hybrids are the o!!spring o! crosses $et"een&i!!erent species

Repro&cti%e isolation can $e classi!ie& $)

"hether !actors act $e!ore or a!ter !ertili-ation


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Prezygotic barriers $loc. !ertili-ation !ro#occrring $)/

I#pe&ing &i!!erent species !ro# atte#pting to

#ate

Pre%enting the sccess!l co#pletion o! #ating

Hin&ering !ertili-ation i! #ating is sccess!l


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Prezygotic barriers

Habitat Isolation

Individuals

ofdifferentspecies

Temporal Isolation ehavioral Isolation

!atingattempt

!echanical Isolation "ametic Isolation

#ertilization

$educed Hybrid %iability $educed Hybrid #ertility

Postzygotic barriers

Hybrid rea&down

%iable'fertile

offspring

(a)

(b)

(d)

(c) (e) (f) (g) (h) (i)

()

(l)

(&)


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Habitat isolation/ T"o species enconter eachother rarel)' or not at all' $ecase the)

occp) &i!!erent ha$itats' e%en thogh not

isolate& $) ph)sical $arriers


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(a)

ater*dwelling Thamnophis


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(b)

Terrestrial Thamnophis


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Temporal isolation/ Species that $ree& at&i!!erent ti#es o! the &a)' &i!!erent seasons'

or &i!!erent )ears cannot #i* their ga#etes


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(c)

+astern spotted s&un&(Spilogale putorius)


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(d)

estern spotted s&un&(Spilogale gracilis)


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(e)

,ourtship ritual of blue*footed boobies

Behavioralisolation/Cortship ritals

an& other

$eha%iors ni0eto a species are

e!!ecti%e $arriers


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(f)

Bradybaenawith shellsspiraling in oppositedirections

Mechanicalisolation/1orphological

&i!!erences can

pre%entsccess!l

#ating


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(g)

Sea urchins

Gametic isolation/Sper# o! one species#a) not $e a$le to

!ertili-e eggs o!

another species


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Postzygotic barriers pre%ent the h)$ri&-)gote !ro# &e%eloping into a %ia$le' !ertile

a&lt/ Re&ce& h)$ri& %ia$ilit)

Re&ce& h)$ri& !ertilit)

H)$ri& $rea.&o"n


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Reduced hybrid viability/ Genes o! the&i!!erent parent species #a) interact an&i#pair the h)$ri&2s &e%elop#ent


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(i)

Don&ey


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()

Horse


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(&)

!ule (sterile hybrid)


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Hybrid breakdown/ So#e !irst3generationh)$ri&s are !ertile' $t "hen the) #ate "ith

another species or "ith either parent species'o!!spring o! the ne*t generation are !ee$le or

sterile


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(l)

Hybrid cultivated rice plants with

stunted offspring (center)


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Limitations of the Biological

Species ConceptThe biological species concept cannot $e applie& to !ossils or ase*al organis#s +incl&ing allpro.ar)otes,


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Other De!initions o! Species

Other species concepts e#phasi-e the nit)"ithin a species rather than the separatenesso! &i!!erent species

The morphological species concept &e!ines aspecies $) strctral !eatres It applies to se*al an& ase*al species $t

relies on s$4ecti%e criteria


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The ecological species concept%ie"s aspecies in ter#s o! its ecological niche

It applies to se*al an& ase*al species an&e#phasi-es the role o! &isrpti%e selection

The phylogenetic species concept/ &e!ines a

species as the s#allest grop o! in&i%i&als ona ph)logenetic tree

It applies to se*al an& ase*al species' $t it

can $e &i!!iclt to &eter#ine the &egree o!&i!!erence re0ire& !or separate species


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Speciation can ta.e place "ith or "ithot

geographic separation Speciation can occr in t"o "a)s/

llopatricspeciation

!ympatricspeciation

SPECIATION3 The process o! Biological Species For#ation5


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(a) -llopatric speciation (b) Sympatric speciation


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Allopatric +6Other Contr)7,

Speciation

In allopatric speciation' gene !lo" is

interrpte& or re&ce& "hen a poplation is&i%i&e& into geographicall) isolate&

s$poplations


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The Process of Allopatric

Speciation The &e!inition o! barrier&epen&s on the a$ilit) o! apoplation to &isperse

Separate poplations #a) e%ol%e in&epen&entl)throgh #tation' natral selection' an& genetic &ri!t


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A. harrisi A. leucurus


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Evidence of Allopatric

SpeciationRegions "ith #an) geographic $arriers

t)picall) ha%e #ore species than &o regions

"ith !e"er $arriers

8 Repro&cti%e isolation $et"een poplations

generall) increases as the &istance $et"een

the# increases


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!antellinae(!adagascar only)./00 species

$hacophorinae(India1Southeast-sia). 2/0 species

3ther Indian1

Southeast -sian

frogs

!illions of years ago (mya)

/ 4 2

/ 4 2

/00 50 60 70 40 0

55 mya 68 mya 86 mya

India

!adagascar


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S)#patric +6Sa#e Contr)7,

Speciation In sympatric speciation' speciation ta.es place in geographicall) o%erlapping poplations


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Polyploidy

Polyploidy is the presence o! e*tra sets o!chro#oso#es &e to acci&ents &ring cell&i%ision

An autopolyploid is an in&i%i&al "ith #ore

than t"o chro#oso#e sets' &eri%e& !ro# onespecies

An allopolyploid is a species "ith #ltiplesets o! chro#oso#es &eri%e& !ro# &i!!erentspecies


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4n9 6 7n9 /4

#ailure of celldivision afterchromosomeduplication givesrise to tetraploid

tissue:

4n

"ametesproducedare diploid::

7n

3ffspring withtetraploid&aryotypes maybe viable andfertile:


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Species -

4n9 6

;ormalgameten9 2

!eiotic

error

Species 4n9 7


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Pol)ploi&) is #ch #ore co##on in plants

than in ani#als

1an) i#portant crops +oats' cotton' potatoes'to$acco' an& "heat, are pol)ploi&s

S l S l ti


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Seual Selection!e"ual selection can &ri%e s)#patric

speciation

Se*al selection !or #ates o! &i!!erent colors

has li.el) contri$te& to the speciation in

cichli& !ish in La.e 9ictoria


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+>P+$I!+;T

;ormal light !onochromaticorange light

P.pundamilia

P. nyererei


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Allopatric an& S)#patric

Speciation/A Revie!

In allopatric speciation' geographic isolation

restricts gene !lo" $et"een poplationsRepro&cti%e isolation #a) then arise $)

natral selection' genetic &ri!t' or se*al

selection in the isolate& poplations

E%en i! contact is restore& $et"een

poplations' inter$ree&ing is pre%ente&


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In s)#patric speciation' a repro&cti%e $arrier

isolates a s$set o! a poplation "ithot

geographic separation !ro# the parent species

S)#patric speciation can reslt !ro#

pol)ploi&)' natral selection' or se*al

selection

H)$ri& -ones pro%i&e opportnities to st&)


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H)$ri& -ones pro%i&e opportnities to st&)

!actors that case repro&cti%e isolation

Ahybrid zone

is a region in "hich #e#$ers o!

&i!!erent species #ate an& pro&ce h)$ri&s

Patterns :ithin H)$ri& ;ones


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Patterns :ithin H)$ri& ;ones

A h)$ri& -one can occr in a single $an&

"here a&4acent species #eetH)$ri&s o!ten ha%e re&ce& !itness co#pare&

"ith parent species

The &istri$tion o! h)$ri& -ones can $e #oreco#ple* i! parent species are !on& in

#ltiple ha$itats "ithin the sa#e region


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+


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"usion# $ea%ening

Reproductive Barriers I! h)$ri&s are as !it as parents' there can $e

s$stantial gene !lo" $et"een species

I! gene !lo" is great enogh' the parentspecies can !se into a single species


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Pundamilia nyererei Pundamilia pundamilia

Pundamilia turbid water,hybrid offspring from a location

with turbid water

Stability# Continued "ormation of &ybrid


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Stability# Continued "ormation of &ybrid

Individuals

E*tensi%e gene !lo" !ro# otsi&e the h)$ri&

-one can o%er"hel# selection !or increase&

repro&cti%e isolation insi&e the h)$ri& -one

In cases "here h)$ri&s ha%e increase& !itness'

local e*tinctions o! parent species "ithin theh)$ri& -one can pre%ent the $rea.&o"n o!

repro&cti%e $arriers


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GA1E< +$) grop,

= points !or e%er)

correctAns"er

Cynotilapia afra' intro&ce& at :est Th#$i Islan& in La.e


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1ala"i in the >?@s' has split into t"o geneticall) &istinct

poplations' locate& at the north an& soth en&s o! the islan&5

Ho" can scientists &eter#ine "hether these poplations are

no" &i!!erent species' accor&ing to the $iological speciesconcept

a, See "hether the t"o poplations are #orphologicall)

&i!!erent !ro# each other/ coloring' $one strctre' an&so on5

$, Deter#ine "hether captre& in&i%i&als !ro# the t"o

&i!!erent poplations "ill #ate an& pro&ce o!!spring in

a la$orator) !ish tan.5c, Deter#ine "hether in&i%i&als !ro# one poplation

"ill inter$ree& "ith in&i%i&als !ro# the other

poplation "hen intro&ce& into each other2s nati%e

ha$itats5



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1ala"i in the >?@s' has split into t"o geneticall) &istinct

poplations' locate& at the north an& soth en&s o! the islan&5

Ho" can scientists &eter#ine "hether these poplations are

no" &i!!erent species' accor&ing to the $iological speciesconcept

a, See "hether the t"o poplations are #orphologicall)

&i!!erent !ro# each other/ coloring' $one strctre' an&so on5

$, Deter#ine "hether captre& in&i%i&als !ro# the t"o

&i!!erent poplations "ill #ate an& pro&ce o!!spring in

a la$orator) !ish tan.5c# $etermine whether individuals from one population

will interbreed with individuals from the otherpopulation when introduced into each other%s native

habitats&

Cichli&s in La.e 9ictoria are thoght to ha%e


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&i%ersi!ie& !ro# a relati%el) !e" species to

@ species in a$ot >=' )ears +the last

ti#e the la.e &rie& p,5 :hat is the $est "a)to test this h)pothesisa, E*a#ine the !ossil recor& in la.e se&i#ents5

$, Loo. !or #orphological characteristics share& a#ong La.e 9ictoria species

that are &istinct !ro# the species present in other la.es5

c, Loo. !or genetic characteristics share& a#ongLa.e 9ictoria species that are &istinct !ro#

species present in other la.es5

&, This is not a testa$le h)pothesis5



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&i%ersi!ie& !ro# a relati%el) !e" species to

@ species in a$ot >=' )ears +the last

ti#e the la.e &rie& p,5 :hat is the $est "a)to test this h)pothesisa, E*a#ine the !ossil recor& in la.e se&i#ents5

$, Loo. !or #orphological characteristics share& a#ong La.e 9ictoria species

that are &istinct !ro# the species present in other la.es5

c# 'ook for genetic characteristics shared among 'ake (ictoria speciesthat are distinct from species present in other lakes&

&, This is not a testa$le h)pothesis5

In "hat t)pe o! en%iron#ent is a scientist


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#ost li.el) to !in& e*a#ples o! ongoing

speciationa, areas that ha%e a large range o! altit&es' sch as #ontains an& &eep%alle)s

$, areas sch as large plains that !acilitate #igration o! ani#als

c, e*tre#e ph)sical en%iron#ents that are #arginal !or spporting li!e

&, areas that are alrea&) species3rich

e, areas that ha%e n&ergone recent en%iron#ental &istr$ance or change



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#ost li.el) to !in& e*a#ples o! ongoing

speciationa, areas that ha%e a large range o! altit&es' sch as #ontains an& &eep%alle)s

$, areas sch as large plains that !acilitate #igration o! ani#als

c, e*tre#e ph)sical en%iron#ents that are #arginal !or spporting li!e

&, areas that are alrea&) species3rich

e# areas that have undergone recent environmental disturbance or change

Sea rchins are $roa&cast spa"ners/ The)


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release their ga#etes into the "ater "ithot

cortship5 :hich o! these repro&cti%e

isolation #echanis#s is #ost li.el) a!!ectingsea rchinsa, $eha%ioral isolation or #echanical isolation

$, ga#etic isolation or te#poral isolation

c, ha$itat isolation



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release their ga#etes into the "ater "ithot

cortship5 :hich o! these repro&cti%e

isolation #echanis#s is #ost li.el) a!!ectingsea rchinsa, $eha%ioral isolation or #echanical isolation

b# gametic isolation or temporal isolation

c, ha$itat isolation

o spot a sea sna.e "hile )o are in a $oat


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on the ocean an& re#ar. a$ot ho" si#ilar it

loo.s to a sna.e that li%es in central Illinois5

Ho"e%er' )o .no" that the) are #ost li.el)separate species &e to "hich o! the

!ollo"ing repro&cti%e $arriersa, $eha%ioral isolation

$, ga#etic isolationc, ecologicalha$itat isolation

&, te#poral isolation



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on the ocean an& re#ar. a$ot ho" si#ilar it

loo.s to a sna.e that li%es in central Illinois5

Ho"e%er' )o .no" that the) are #ost li.el)separate species &e to "hich o! the

!ollo"ing repro&cti%e $arriersa, $eha%ioral isolation

$, ga#etic isolationc# ecological)habitat isolation


The centr) cacts !lo"ers e%er) > )ears5


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A si#ilar cacts !lo"ers e%er) )ears5 I! the

3)ear cacts pollen has the correct

characteristics to !ertili-e the centr)cacts' "hich repro&cti%e $arrier "ill #ost

li.el) $e "or.ing against that possi$ilit)a, $eha%ioral isolation





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A si#ilar cacts !lo"ers e%er) )ears5 I! the

3)ear cacts pollen has the correct

characteristics to !ertili-e the centr)cacts' "hich repro&cti%e $arrier "ill #ost

li.el) $e "or.ing against that possi$ilit)a, $eha%ioral isolation


d# temporal isolation

Se%eral species o! a#phi$ians are a$le to


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rea& each other2s #ating ritals an&

n&erstan& the#' ten& to $e !ertile at the

sa#e ti#e' an& are sall) si#ilar in si-e5Ho"e%er' "hen the) atte#pt to #ate' the)

ne%er pro&ce o!!spring5 :hich o! the

!ollo"ing $arriers is #ost li.el) the case o!this

a, $eha%ioral isolation

$, ga#etic isolation

c, re&ce& h)$ri& !ertilit)

&, h)$ri& $rea.&o"n



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rea& each other2s #ating ritals an&

n&erstan& the#' ten& to $e !ertile at the

sa#e ti#e' an& are sall) si#ilar in si-e5Ho"e%er' "hen the) atte#pt to #ate' the)

ne%er pro&ce o!!spring5 :hich o! the

!ollo"ing $arriers is #ost li.el) the case o!this

a, $eha%ioral isolation

b# gametic isolation

c, re&ce& h)$ri& !ertilit)

&, h)$ri& $rea.&o"n

:hen &i!!erentiating $et"een t"o species o!


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!ish' )o notice that one species sta) near

the sr!ace an& !ee& on !loating algae' "hile

the other species are $otto# !ee&ers5 This issing thea, #orphological species concept5

$, ecological species concept5

c, ph)logenetic species concept5



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: e & e e t at g $et"ee t"o spec es o

!ish' )o notice that one species sta) near

the sr!ace an& !ee& on !loating algae' "hile

the other species are $otto# !ee&ers5 This issing thea, #orphological species concept5

b# ecological species concept&

c, ph)logenetic species concept5

:hich o! the !ollo"ing is $elie%e& to $e the


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g

pri#ar) repro&cti%e isolation #echanis# !or

casing s)#patric speciation in North

A#erican apple #aggot !lies +Rhagoletispomonella,

a, pol)ploi&)

$, se*al selection

c, ph)logenetic species concept

&, ha$itat &i!!erentiation

:hich o! the !ollo"ing is $elie%e& to $e the


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g

pri#ar) repro&cti%e isolation #echanis# !or

casing s)#patric speciation in North

A#erican apple #aggot !lies +Rhagoletispomonella,

a, pol)ploi&)

$, se*al selection

c, ph)logenetic species concept

d# habitat differentiation


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For FI9E POINTS5 :hat &o )o call an o!!spring o! t"o &i!!erent ani#als or plants o! &i!!erent

races' $ree&s' %arieties an& species5


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=5 :ho !or#late& the $iological species concept


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5 De!ines a species $) strctral !eatres5 It applies to se*al an& ase*al species $t

relies on s$4ecti%e criteria


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5 It %ie"s a species in ter#s o! its ecological

niche5 It applies to se*al an& ase*al species an& e#phasi-es the role o!&isrpti%e selection5


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"# T$e di%%erentiation o% geogra&$i'ally

solated &o&ulations into distin't

S&e'ies#


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CH 24 PPT the Origin of Species