Spe c ie s Ric hne ss MODUL E 13: SPE CI E S RI CHNE SS UNI - - PDF document

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Spe c ie s Ric hne ss MODUL E 13: SPE CI E S RI CHNE SS UNI - - PDF document

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Spe c ie s Ric hne ss MODUL E 13: SPE CI E S RI CHNE SS UNI T 3: E COL OGI CAL BI OGE OGRAPHY Ob je c tive s At the e nd o f this se rie s o f le c ture s yo u sho uld b e a b le to : De fine te rms. De sc rib e

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SLIDE 1

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Spe c ie s Ric hne ss

MODUL E 13: SPE CI E S RI CHNE SS UNI T 3: E COL OGI CAL BI OGE OGRAPHY

Ob je c tive s

 At the e nd o f this se rie s o f le c ture s yo u sho uld b e a b le to :

 De fine te rms.  De sc rib e the ro le o f isla nds in b io g e o g ra phy a nd c o mmunity e c o lo g y  Diffe re ntia te b e twe e n the Sta tic T

he o ry o f I sla nds a nd the E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy.

 De sc rib e the Spe c ie s-Are a a nd Spe c ie s-I

so la tio n re la tio nships

 Disc uss Pre sto n’ s e xpla na tio n o f the Spe c ie s-Are a re la tio nship.  Disc uss a nd g ive e xa mple s o f spe c ie s turno ve r.  E

xpla in a nd de mo nstra te the E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Disc uss the a dva nta g e s a nd limita tio ns o f the E

q uilib rium T he o ry o f I sla nd Bio g e o g ra phy.

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SLIDE 2

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I sla nds a re I nflue ntia l

 We ll de fine d  Re la tive ly simple b io ta s  Nume ro us  Na tura l e xpe rime nts

 Are a  I

so la tio n

 Pre da tio n a nd c o mpe titio n

Sta tic T he o ry o f I sla nds

 Co mmunity struc ture o n isla nds wa s fixe d

 E

vo lutio na ry e ve nts (o ve re mpha size d)

 Uniq ue immig ra tio n e ve nts (no g e ne ra l pa tte rn)  Uniq ue e xtinc tio n e ve nts (no g e ne ra l pa tte rn)  Numb e r o f nic he s o n the isla nd we re fixe d  “E

ithe r a spe c ie s ha d a lre a dy c o lo nize d a n isla nd o r it ne ve r wo uld.”

 No g e ne ra l e xpla na tio ns o r mo de ls

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SLIDE 3

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Dyna mic E q uilib riums

 Oppo sing fo rc e s ma inta in c o nsta nc y in so me c ha ra c te ristic o f a

syste m de spite c o ntinua l c ha ng e s in o the r intrinsic pro pe rtie s o f the syste m.

 Wa rm-b o die d a nima l e xa mple .

 Pa ra dig m shift

 So ug ht g e ne ra l pa tte rns  So ug ht g e ne ra l e c o lo g ic a l e xpla na tio ns to tho se pa tte rns  L

e ss e mpha sis o n e xpla ining the idio sync ra tic o r e xc e ptio na l

  • b se rva tio ns.

I sla nd Pa tte rns

 T

he numb e r o f spe c ie s te nds to inc re a se with isla nd a re a

 T

he numb e r o f spe c ie s te nds to de c re a se with inc re a se d iso la tio n o f the isla nd.

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SLIDE 4

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Spe c ie s-Are a Re la tio nship

 Sc ho e ne r -- “o ne o f c o mmunity e c o lo g y’ s fe w la ws”  Mo st g e ne ra l, b e st-do c ume nte d pa tte rns in na ture .

Spe c ie s-Are a Re la tio nship

 Arrhe nius e q ua tio n / Po we r mo de l

 Mo difie d fro m the Allo me tric e q ua tio n (sc a ling mo rpho lo g y a nd

me ta b o lic pro c e sse s)

 Also c a lle d the po we r mo de l

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SLIDE 5

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Spe c ie s-Are a Re la tio nship

 Arrhe nius e q ua tio n / Po we r mo de l

 S = Spe c ie s ric hne ss  c = A fitte d c o nsta nt (ta xo no mic g ro up a nd re g io n – spe c ie s so urc e )  A = Are a  z = A fitte d c o nsta nt (re g io n – the type o f the a re a sa mple d)

Spe c ie s-Are a Re la tio nship

 Arrhe nius e q ua tio n / Po we r mo de l

 L

  • g tra nsfo rm o f the po we r mo de l

 We c a n no w e stima te c a nd z fro m simple line a r re g re ssio n o n the lo g

tra nsfo rme d spe c ie s ric hne ss a nd lo g tra nsfo rme d a re a .

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SLIDE 6

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Spe c ie s-Are a Re la tio nship

 c is fre q ue ntly inte rpre te d a s the inte rc e pt (this fo llo ws fro m the lo g

tra nsfo rme d line a r e q ua tio n)

 T

he a c tua l inte rc e pt o f the po we r mo de l is 0

 z is fre q ue ntly inte rpre te d a s the slo pe (this fo llo ws fro m the lo g

tra nsfo rme d line a r e q ua tio n)

 z de sc rib e s the re la tio nship b e twe e n L

  • g S a nd L
  • g A – no t the

re la tio nship b e twe e n S a nd A

 T

he re la tio nship b e twe e n S a nd A (ho w q uic kly S inc re a se s a s A inc re a se s) is influe nc e d b y b o th c a nd z.

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Spe c ie s-Are a Re la tio nship

 Mo st a rg ume nts re la te d to spe c ie s-a re a re la tio nships fo c us o n

c o mpa riso ns o f the “slo pe ” z a s if z wa s the e ntire sto ry.

 z va rie s o nly slig htly

 T

ypic a lly b e twe e n 0.15 a nd 0.35

 Co ntine nts te nd to 0.15  I

sla nds te nd to 0.35

 T

he o re tic a l va lue 0.25 (de rive d b y Pre sto n – mo re o n this in a mo me nt)

 c va rie s c o nside ra b ly  By o nly c o mpa ring z-va lue s we a re missing the po int.

Spe c ie s-Are a Re la tio nship

 Pre sto n’ s e xpla na tio n fo r the Spe c ie s-Are a Re la tio nship

 A c o mmunity’ s spe c ie s a b unda nc e c urve te nds to a ppro xima te a

trunc a te d o r c a no nic a l lo g no rma l distrib utio n.

 T

runc a tio n o r ve il line

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SLIDE 8

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Spe c ie s-Are a Re la tio nship

 Pre sto n’ s e xpla na tio n fo r the Spe c ie s-Are a Re la tio nship

 As the a re a inc re a se s the numb e r o f individua ls sa mple d will inc re a se –

inc re a sing the pro b a b ility tha t a n individua l o f a ra re spe c ie s is inc lude d – inc re a sing the spe c ie s ric hne ss.

 L

a rg e r a re a s will inc o rpo ra te ne w kinds o f ha b ita ts with its a sso c ia te d spe c ie s.

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SLIDE 9

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Spe c ie s-I so la tio n Re la tio nship

 I

sla nds fa r o ut in a n o c e a n suppo rt fe we r spe c ie s tha n isla nds tha t a re ne a re r to c o ntine nts.

 Assuming tha t pa tte rn is the re sult fro m a de c line in dispe rsa l ra te s

with iso la tio n the re la tio nship b e twe e n spe c ie s ric hne ss a nd iso la tio n sho uld b e :

 Ne g a tive e xpo ne ntia l func tio n  Ne g a tive sig mo ida l func tio n

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Spe c ie s-I so la tio n Re la tio nship

 L

e ss g e ne ra l tha n the spe c ie s-a re a re la tio nship

 I

nc lude b ro a d ra ng e s o f diffe re nc e s in a re a , b ut o nly limite d ra ng e s o f diffe re nc e s in iso la tio n.

 Re le va nt me a sure s o f iso la tio n a re c ha lle ng ing .

Spe c ie s T urno ve r

 K

ra ka ta u

 Pa tte rn

 Spe c ie s ric hne ss inc re a se s ra pidly initia lly  Spe c ie s ric hne ss the n sta b ilize s –re ma ining re la tive ly c o nsta nt  Cha ng e s in the c o mpo sitio n o f the b io ta c o ntinue s.

 Spe c ie s ric hne ss re ma ins re la tive ly c o nsta nt, b ut the ide ntity o f the

spe c ie s c o ntinue s to c ha ng e .

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Ama zo n Re vie w

E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 I

nc o rpo ra te s the diffe re nt isla nd pa tte rns tha t we ha ve disc usse d.

 Spe c ie s-Are a re la tio nship  Spe c ie s-I

so la tio n re la tio nship

 Spe c ie s turno ve r

E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Spe c ie s ric hne ss o n isla nds c a n b e e xpla ine d b y two fa c to rs.

 I

sla nd a re a

 I

sla nd iso la tio n

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Are a re g ula te s spe c ie s ric hne ss o n isla nds b y c o ntro lling po pula tio n

size

 A stro ng inve rse c o rre la te o f e xtinc tio n.  T

he sma lle r the isla nd the sma lle r the po pula tio n tha t c a n b e suppo rte d

  • n the isla nd.

 T

he sma lle r the po pula tio n size the mo re like ly it will b e c o me e xtinc t.

 T

he sma lle r the isla nd the g re a te r the pro b a b ility o f a ny spe c ie s g o ing e xtinc t.

E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 On a diffe re nt b ut re la te d to pic .

 T

he g re a te r the numb e r o f spe c ie s in a ny c o mmunity the g re a te r the pro b a b ility tha t a ny o ne spe c ie s will g o e xtinc t.

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 No w we c a n c o mb ine the two c o nc e pts re la te d to e xtinc tio n into a

sing le g ra ph.

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 All spe c ie s ha ve so me limit to the ir dispe rsa l a b ility.

 So me spe c ie s will b e a b le to dispe rse lo ng dista nc e s.  So me spe c ie s will a b le to dispe rse o nly sho rt dista nc e s.  T

he isla nds ve ry c lo se to a c o ntine nt will ha ve a ll o f the spe c ie s (spe c ie s c a pa b le o f o nly limite d dispe rsa l a nd tho se c a pa b le o f lo ng dista nc e dispe rsa l)

 I

sla nds isla nd ve ry fa r a c o ntine nt will ha ve ve ry fe w spe c ie s (o nly tho se spe c ie s c a pa b le o f lo ng dista nc e dispe rsa l).

 T

he numb e r o f spe c ie s o n a n isla nd will b e inve rse ly re la te d to its dista nc e fro m a c o ntine nt.

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SLIDE 16

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 On a diffe re nt b ut re la te d to pic .

 T

he mo re spe c ie s o n a n isla nd the le ss like ly tha t a ny immig ra nt a rriving a t the isla nd will re pre se nt a ne w spe c ie s.

 T

he re fo re the immig ra tio n ra te de c line s with inc re a se d spe c ie s ric hne ss

  • n a n isla nd.
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SLIDE 17

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 No w we c a n c o mb ine the two c o nc e pts re la te d to e xtinc tio n into a

sing le g ra ph.

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SLIDE 18

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Any g ive n isla nd is de fine d b y its a re a a nd its iso la tio n.  Be c a use e xtinc tio n ra te (a func tio n o f a re a ) a nd immig ra tio n ra te (a

func tio n o f iso la tio n) c a n b o th b e de sc rib e d b y spe c ie s ric hne ss, we c a n c o mb ine the m into a sing le g ra ph.

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SLIDE 19

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Dyna mic e q uilib rium  Spe c ie s T

urno ve r

 Go b a c k a slide

E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 No t a ll isla nds ha ve e q ua l a re a o r iso la tio n.  Pre dic tio ns o n ho w spe c ie s ric hne ss sho uld va ry with iso la tio n a nd

a re a .

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SLIDE 20

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 I

sla nd b io g e o g ra phy the o ry a ssume s tha t a re a c o ntro ls e xtinc tio n, iso la tio n c o ntro ls immig ra tio n, a nd tha t ne ithe r influe nc e s the o the r -

  • a hig hly ide a lize d sc e na rio .
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SLIDE 21

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 T

a rg e t e ffe c t -- L a rg e r isla nds o ffe r a la rg e r ta rg e t fo r immig ra nts, so a re a c a n influe nc e immig ra tio n.

E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Re sc ue e ffe c t -- Ve ry sma ll isla nds, tha t sho uld ha ve ve ry hig h

e xtinc tio n ra te s c a n ma inta in po pula tio ns if the ma inla nd is c lo se e no ug h tha t immig ra nts a re ple ntiful a nd sta b ilize d the po pula tio ns.

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SLIDE 22

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E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 Adva nta g e s

 Gra phic a l pre se nta tio n – no ne e d to do a ll o f the ma th  Ge ne ra l  Mo de l ha d c le a r te sta b le pre dic tio ns

 Mo st ma the ma tic a l mo de ls in e c o lo g y a re no t te sta b le  Pre dic ts tre nds in spe c ie s ric hne ss  Pre dic ts turno ve r ra te s

E q uilib rium T he o ry o f I sla nd Bio g e o g ra phy

 L

imita tio ns

 So simple tha t it o b sc ure s pa tte rns a nd pro c e sse s  Ma ny (mo st? ) isla nds a re no t in e q uilib rium  Ide ntitie s a nd c ha ra c te ristic s o f spe c ie s a re ig no re d  Inte ra c tio ns a mo ng spe c ie s a re no t inc lude d  Immig ra tio n a nd e xtinc tio n a re tre a te d a s inde pe nde nt pro c e sse s  Me a suring a re a a nd iso la tio n  Diffic ult to ide ntify so urc e s o f isla nds c o lo nists a prio ri  E

vo lutio n o n isla nds vio late s a ssumptio ns

 Disturb a nc e o n isla nds  Are a is o nly a n indire c t me a sure o f a n isla nd’ s a b ility to ma inta in spe c ie s.

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SLIDE 23

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T e sts o f E T I B

 K

ra ka ta u

 E

xpe rime nta l de fa una tio n – Simb e rlo ff a nd Wilso n

 I

sla nds o f Pa na ma Ca na l (Ba rro Co lo ra do ) – Re la xa tio n

 I

nte rmo nta ne we st – Ple isto c e ne re fug ia – Re la xa tio n

Sma ll I sla nd E ffe c t

 Spe c ie s-a re a re la tio nship do e s no t wo rk fo r ve ry sma ll isla nds.

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SLIDE 24

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Sma ll I sla nd E ffe c t

 L

  • mo lino a nd We ise r

 Sma ll isla nd e ffe c t is c o mmo n  Va ria tio n ma ke s se nse re la tive to fo c a l ta xa

 Re so urc e re q uire me nts  I

mmig ra tio n a b ility (re la tive iso la tio n o f b io ta )

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SLIDE 25

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No ne q uilib rium Bio ta s

 I

mmig ra tio n a nd E xtinc tio n a re no t b a la nc e d.

 One pro c e ss do mina te s  Ple isto c e ne re fug ia

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SLIDE 26

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I nte re sting Applic a tio n

 L

a nd Bridg e I sla nds

 Gla c ia tio n ~ Se a L

e ve l

 Co nne c tio ns to ma inla nd  Cha ng e s in isla nd a re a  I

nte rg la c ia l

 E

xtinc tio ns  Co nse rva tio n  De mo nstra te o n g ra ph