vii. classification of the tribe a numerical...

VII . CLASSIFICATION OF THE TRIBE

A NUMERICAL APPROACH

VII . CLASSIFICATION OF THE TRIBE HELlANTHEAE - A NUMERICAL APPROACH

(I Sneath and Sokal (1962) de f i ned numer ica l taxonomy as t h e

numer ica l evaluat ion o f the a f f i n i t y o r s i m i l a r i t y between

taxonomic un i t s and the o rde r ing o f these un i ts in to taxa on t h e

\I

bas is o f t h e i r a f f i n i t i es . It a lso ' encompasses " t h e drawing o f

phy logene t i c inferences from the data b y s t a t i s t i c a l o r o ther

mathemat ica l methods". The aim, p r i n c i p l e s and p h i l o s o ~ h y

b e h i n d t h e numerical taxonomy are e legant ly presented b y t h e

above worke rs i n t h e i r c lass ica l book on numerical taxonomy.

Stated i n a nut she l l , the who le "opera t ion of the numerical

taxonomy can- ' be c a r r i e d out i n the fo l l ow ing sequences :

Organisms and charac ters a r e chosen and recorded; t h e

resemblances between the' organisms a r e calculated; taxa are based

on these resemblances; and las t general i sa t ions are made about the

taxa" (Sneath and Sokal, 1963). B o t h ' p h e n o t y ~ i c ' and

I phy logene t i c ' re la t ionsh ips can b e e luc ida ted b y t h e appropr ia te

numer ica l taxonomic methods.

Numerical taxonomy has t h e v e r s a t a l i t y t o integrate data

from d i v e r s e sources (such as f rom morphology, cyto logy,

c h e m i s t r y e tc ) . According to t h e pro togon is ts o f t h i s system, t h e

numer ica l taxonomic methods be ing quan t i t a t i ve , p r o v i d e greater

d isc r im ina t i on along t h e spectrum o f taxonomic d i f f e rences and a r e

more sens i t i ve i n d e l i m i t i n g taxa; and the reby t h e y shou ld

g i v e be t te r taxonomic keys and c lass i f i ca t ion . The methods o f

numerical taxonomy h a v e become power fu l too ls i n t he hands o f

t h e taxonomists, no t on l y f o r t he i den t i f i ca t i on o f taxa and t h e i r

in te r re la t ionsh ips , b u t a lso i n answering and i n te rp re t i ng a number

o f b io log ica l concepts and t o t h e pos ing o f new b io log i ca l and

evo lu t ionary quest ions.

The bas i c u n i t o f numerical. taxonomy i s t h e 'Operat ional

Taxonomic Un i t (OTU) ' , w h i c h i s t h e term g iven to t h e lowest

taxon being s tud iea i n a p a r t i c u l a r invest igat ion. They can b e

fami l ies, genera, species o r i n d i v i d u a l s o r any o t h e r taxonomic

e n t i t y . Each OTU has t o b e scored f o r t h e possession o f one o r

more ' charac ter s t a t e s ' o r a t t r i b u t e s f o r each cha rac te r w h i c h

r e s u l t s i n a data m a t r i x o f a t t r i bu tes . T h i s da ta m a t r i x i s then . analysed using one o r more o f t h e many methods ava i lab le .

Many w e l l c a r r i e d out numerical taxonomic studies have

been repor ted d u r i n g t h e l a s t two decades o f i t s existence, a

comprehensive r e v i e w o f w h i c h i s g iven b y Sneath and Sokal

( 1 9 6 3 ) . These s tud ies a l so show t h e a d a p t a b i l i t y o f t h e

numer ica l taxonomic methods t o any l eve l o f taxonomic

organisation, subspec i f i c , spec i f i c , generic, f a m i l i a l and

suprafami l i a l l eve l s .

C l u s t e r Ana lys i s - Numerical technique u s e d i n t h e present s t u d y

The ob jec t i ve o f c l us te r ana lys i s i s t o dev i se a

c l a s s i f i c a t i o n scheme f o r grouping a g i ven se t o f v a r i a b l e s o r

i n d i v i d u a l s (each of wh ich i s d e s c r i b e d b y a set o f numerical

measures) i n to a number o f c lasses such tha t objects w i t h i n

classes are s i m i l a r i n some respect and d i f f e r e n t from those i n

o the r classes.

The present s tudy i s an a t tempt t o c l a s s i f y 39 taxa based

on t h e fo l l ow ing 37 parameters.

Achene main a x i s ( l eng th i n mm)

Achene cross a x i s (d iameter i n mml

Pa l isade ra t io .

Stomata1 index (upper1

Stomata1 inqex ( l o w e r )

Stomata1 frequency (upper )

Stomata1 frequent;/ ( l ower )

Guard c e l l s i ze ( l eng th i n p m )

Guard c e l l s i ze ( b r e a d t h i n pm)

Po lar diameter i n pm

Equator ia l d iameter i n p m

Spine he igh t (pm)

Distance between adjacent sp ines (pm)

Ex ine th ickness (pm)

B read th o f roo t vessel i n pm

Length o f r o o t vessel i n pm

Bread th o f nodal vessel i n prn

Length o f nodal vessel i n p m

Bread th o f in ternodal vessel i n pm

Length of in ternodal vessel i n

Shape o f t h e leaf apex

Shape o f t h e lea f base

Margin o f t h e lea f

Tex ture o f t h e lea f

Nature o f p r i m a r y v e i n

Type o f venat ion

Marginal u l t ima te venat ion

Shape o f t h e leaf

Achene shape

Colour o f t h e achene

Nature o f pappus

Surface ornamentation I S E M )

Vein- is le t numberlmm2

Vein let enter ing t iumberlmm2

Vein ending terminat ion number lmm2

Absolute v e i n - i s l e t number i n thousands

Absolute ve in le t terminat ion number i n thousands.

Ana lys is i s done us ing 4 d i f f e r e n t methods viz., average

l inkage, complete l inkage, c e n t r o i d and median method. The

i npu t data f o r the numerical ana lys i s i s g i ven i n Table.22.

1. Average L inkage Method

I n t h i s method, t h e d i s tance between two groups i s

d e f i n e d as t h e average o f t h e d i s t a n c e s between a l l p a i r s of

i n d i v i d u a l s o f t h e two groups. T h i s method o f c luster ing i s no t

dependent on t h e extreme values f o r de f i n ing c lusters and

acco rd ing l y i t i s not poss ib le t o make any statement about t h e

minimum o r maximum s i m i l a r i t y 9 a i t h i n a c lus te r .

Many average l inkage methods have been developed.

Among these, t h e unweighted p a i r group method using a r i t hme t i c

averages (UPCMA) i s t he one most f r e q u e n t l y used. It r e s t s on

t h e p l a u s i b i l i t y of t he concept o f an average s i m i l a r i t y and

d i s s i m i l a r i t y coef f i c ien t . Average c o r r e l a t i o n s between OTUs have

u s u a l l y been computed as averages o f t h e i r t ransformed values,

w h i c h a r e then back- t ransformed in to c o r r e l a t i o n measures.

. The m a t r i x of co r re la t i on i s p resented i n Table.21. The

cor respond ing dendrogram.of t h e c l u s t e r fo rmed a r e given i n Fiq.

27. From t h e f i g u r e the fo l low ing c l u s t e r s a r e formed.

C lus te r I

Montanoa b i p i n n a t i f i d a C. Koch

Gal insoga p a r v i f l o r a Cav.

Spi lanthes u l ig inosa Sw.

Xanthium ind icum J. Koenig

Wedel ia ch inens is (Osbeck) Mer r .

Wedel ia u r t i c i f o l i a DC.

Sigesbeckia o r i e n t a l i s L.

Rudbeck ia lac in ia ta L.

D a h l i a pinnata Cav.

Acanthospermum h i sp idu rn DC.

C l u s t e r II

Cosmos b ip innatus Cav.

Spi lanthes oleracea L.

Spi lanthes rad icans Jacq.

Gui znt ia abyssin ica (L.f.1 Cass.

T i t h o n i a d i v e r s i f o l i a (Hernsley) A. Gray

C l u s t e r Ill

Zinnia l i nea r i s Benth..

D a h l i a i m p e r i a l i s Roezl .

Cosmos caudatus Kur7th

T i t h o n i a r o t u n d i f o l i a B lake

T i t h o n i a speciosa

Spi lanthes c i l i a t a H.B. K.

C l u s t e r IV

Glossogyne b idens (Retzd

Hel ianthus annuus L.

Hel ianthus l a e t i f l o r u s Pers.

Synedre l l a n o d i f l o r a [L. ) Gaertner

Z inn ia elegans Jacq.

B idens humi l i s H.B. K.

C l u s t e r V

Melampodium paludosum B. H. K.

Cosmos sulphureus Cav.

E c l i p t a p r o s t r a t a (L . ) L. Mant.

Lagascea mo l l i s Cav.

C l u s t e r V I

Wedel ia t r i l o b a t a (L. ) AS. H i t h .

Sp i lan thes ca l va OC. - Eleutheranthera r u d e r a l i s (Swar tz l Sch.

V I I. Bidens pilosa L.

V I I I . Parthenium hys terophon ls L.

IX. Coreopsis g rand i f l o ra Hogg.

X. Glossocardia bosva l lea (L.f.1 OC.

XI. B l a i n v i l l e a acmella (L. ) P h i l i p s o n

2. Complete L inkage ( f a r t h e s t ne ighbour ) Method

T h i s method i s c a l l e d complete l inkage because a l l

e n t i t i e s i n a c lus ter are l i n k e d to each o the r a t some maximum

d i s tance o r minimum s i m i l a r i t y .

The dendrogram obta ined i s g i v e n i n Fig. 28. From t h e

f i g u r e the fo l low ing c lus ters a re formed.

C l u s t e r I


Galinsoga p a r v i f l o r a Cav.

Soilanthes u l iginosa Sw.

Rudbeckia I a c i n i a t a L .

Cosmos sulphureus Cav.

Bidens p i l o s a L.

Dah l ia p innata Cav.

h i s p i d u m DC.

Spi lanthes oleracea L. -- Cosmos b ip innatus Cav.

C lus ter I 1

Guizot ia abyss in ica (L.f.) Cass.

Lagascea mol l i s Cav.

Glossogyne b idens (Retz.)

Hel ianthus lae t i f l o rus Pers.

T i thon ia d i v e r s i f o l i a (Hemsley) A. Gray

Zinnia l i n e a r i s Benth.

C lus te r Ill

Dah l ia i m p e r i a l i s Roezl.

Cosmos caudatus Kunth

T i thon ia r o t u n d i f o l i a B lake

Wedelia chinensis (Osbeck) Merr .

Spi lanthes radicans Jacq.


Wedelia u r t i c i f o l i a DC.

Sigesbeckia o r i e n t a l i s L .

C l u s t e r I V

T i thon ia speciosa

Spi lanthes c i l i a t a H.B. K.

Synedre l la n o d i f l o r a (L. ) Gaertner

Xanthium ind icum J. Koenig

Wedel ia t r i l o b a t a (L. ) AS. H i th .

Spi lanthes c a l v a DC. -

Cluste r V

E leu theranthera r u d e r a l i s (Swartz) Sch.

E c l i p t a p r o s t r a t a ( L . ) L. Mant.

Z innia elegans Jacq.

B idens h u m i l i s H.B. K.

The r e s t o f t h e p lan ts on i n d i v i d u a l c lus ters .

3. Cen t ro id L inkage Method

The c e n t r o i d l inkage method o r t h e unweighted pa i rg roup

c e n t r o i d method (UPGMC] i s perhaps one o f t h e most a t t r a c t i v e

c lus te r i ng techniques used i n taxonomic s tud ies . The method

computes t h e c e n t r o i d o f t h e OTUs tha t j o in t o fo rm c lusters.

Distances a r e then computed between these centro ids. The

c e n t r o i d i s t h e p o i n t i n phenet ic space whoseco-ord inates are the

mean values o f each cha rac te r over t h e g i v e n c lus te r o f OTUs. It

i s a lso t h e centre of g r a v i t y o f t h e c l u s t e r o f OTUs. The

c e n t r o i d represents a p o i n t w i t h i n t h e phenet ic hype rcube and the

co-ord inates are simp1 y t h e observed f requencies o f t h e var ious

cha rac te rs (Sneath and Sokal, 1963)

The dendrogram obta ined i s as i n F ig. 29. The d i f f e r e n t

c lus te rs fo rmed by t h i s method i s as fo l lows.

C lus te r I


Galinsoga p a r v i f l o r a Cav.

Spi lanthes u l ig inosa Sw.

Rudbeckia l a c i n i a ta L.

Spi lanthes rad icans Jacq.

C lus te r II

Guizot ia abyss in ica (L.f.1 Cass.


T i t h o n i a d i v e r s i f o l i a (Hernsley) A. Gray

C lus te r Ill

Xanthium in'dicum J. Koenig

Wedelia ch inens is (Osbeck) Mer r .

Wedelia u r t i c i f o l i a DC.

s iqesbeck ia o r i e n t a l i s L. - E c l i p t a p r o s t r a t a IL . ) L. Mant.

Dah l ia p innata Cav.

Rest o f t h e taxa a r e i n d i f f e r e n t i n d i v i d u a l c lus ters .

Median Method (Centra l o r nodal c lus te r i ng )

C lus te rs fo rmed from t h e dendrogram (Fig. 30) i s as

fo l lows.

C l u s t e r I

plontanoa b i p i n n a t i f i d a C. Koch

Rudbeck ia l ac in ia ta L.

E c l i p t a p r o s t r a t a (L.1 L. Mant.

D a h l i a p innata Cav.

Acanthospermum h i s p i d u m DC.

Cosmos b ip inna tus Cav.

S ~ i l a n t h e s o leracea L.

Cu izo t ia abyss in i ca (L.f.1 Cass. --

Lagascea m o l l i s Cav.

Z innia l i n e a r i s Benth:

D a h l i a i m p e r i a l i s Roezl.

Cosmos caudatus Kun ih

T i t h o n i a r o t u n d i f o l i a Blake

T i t h o n i a speciosa

C l u s t e r II

Sp i lan thes c i l i a t a H.B. K.

Clossogyne b idens (Retz.)

He l ian thus l a e t i f l o r u s Pers.

Cosmos su lphureus Cav.

B idens p i l o s a L.

Spi lan thes rad icans Jacq.

Cal insoga p a r v i f l o r a Cav.

Spi lan thes u l i g inosa Sw.

C l u s t e r Ill


T i thon ia d i v e r s i f o l i a (Hemsley) A. Gray

The r e s t o f t h e taxa are i n s ingu lar c lus te rs .

DISCUSSION

Accord ing to Sneath and SokaI [1963) the taxonomic

systems a r e i n e v i t a b l y o v e r - s i m p l i f i e d representat ions o f the

m a t r i x o f a f f i n i t i e s among the forms s tud ied and there fore one

cannot demand pe r fec t i on o f such systems.

In t h e present study, it i s no tewor thy that , t h e resul ts

ob ta ined f rom t h e d i f f e r e n t methods o f c lus te r ana lys is a re not

uni form. ' Dendrogram revea ls t h a t va r i ous species belonging t o

t h e same genera f a l l under d i f f e r e n t c lus te rs i n a l l t h e th ree

methods. T h i s may be due t o t h e p r o v i s i o n o f some other

Parameters w h i c h a r e not inc luded i n t h e present study, since the

s t u d y i s not a h o l i s t i c one. The c l u s t e r s deve loped i s insu f f i c i -

ent t o show r e l a t i o n s h i p i n nature and t h e r e b y no t t a l l y i n g w i t h

t h e a l r e a d y e x i s t i n g c lass i f i ca t ions (Cassini , 1829; Lessing, 1832;

De Candolle, 1836; Bentham, 1873; Bentham & Hooker, 1876;

Hoffmann, 1890; Stuessy, 1977; and Robinson, 1981 ) .

From t h e present invest igat ion, it can b e i n f e r r e d tha t

these t y p e o f s tud ies would b e more usefu l i n understanding t h e

a f f i n i t i e s i n h i g h e r taxa and f a m i l i e s r a t h e r than between

s u b t r i b e s and genera. The cand ida te fee ls t h a t t h e r e i s scope

f o r f u r t h e r resea rch inc luding more gene t i ca l l y cont ro l led

parameters f o r conc lus ive results.

TABLE 21 : SHOWING MATRIX OF CORRELATION

(Continued. ... 2 )

TABLE 22a : INPUT DATA FOR CLUSTER ANALYSIS

P6 67 .500 66 .600 45 .000 43.000 88.830 36 .000 43.710 40.000 GO. 300 22.500 40.000 89.430

0 .000

27. 5~10 20. 0 0 l : I ( ; . nu0 19 .350 0 . 9 4 0

I I . 340 I S . :>'to

; 1 0 . O ! J O 17. ( ' 4 0

(Continued.. .2)

v 1 v:: V 3

34. 5ti0 :I I .:Jail Z U . 4.10 2 5 . 4 4 0 29.500 37.000 35.1100 ',", : I t l o . > L , , lo( ! Z l i . 0!10 44. 100 45.400 35.000 3 5 . 0 0 0 25. 130 22.370

(Continued. . . 3 )

GO. 000

(Continued. ..4)

5. 000 ti. 000 1 .000 1.000 7 .000 3 .000 3.000 7 .000 0.000 1 . 000 6 .000 1 . 0 0 0 (i. 000 I , . <I00

7 .000 7 .000 5 .000 5 .000 1.000 1 . 0 0 0 1 . 000 7 . t i00

' 8 . 000 1 . :>00 1 .000 ! I . 000 (I. 000 7 .000 7. 000 7.000 7 .000 1.000 3 .000 1.000

4.000 4.000 3.000 I . og0

4.000 4.000 4.000 4.000 (I. 000 5.000 4.000

ti. 000 3.000 3.000 2.000

(Continued.. . 6 )

NOTE : The p lan ts a r e assigned w i t h corresoonding p lan t codes

(PC.1-39) as i n Table 1. 3 7 parameters as mentioned i n

t h e observat ions, used f o r t h i s ana lys is i s denoted as

P1.....P 37 ' The parameters such as shape o f the f r u i t ,

nature o f pappus, leaf shpae, w h i c h cannot b e r e ~ r e s e n t e d

L by numerical val'ues a re denoted w i t h code numbers as i n

Table 22b. A l l t h e o ther proper t ies , o t h e r than the above

mentioned ones are r e ~ r e s e n t e d w i t h t h e i r mean values.

TABLE : 22b

ASSIGNMENT OF CODES

CODE ASSIGNMENT FOR VARIABLES V1, V2, V3 ACCORDING TO DIFFERENT SCIENTISTS' CLAS$,IFICATION :

V1 BY SCIENTIST BENTHAM 8 HOOKER

V2 BY SCIENTIST TOD.F.STUESSY

V3 BY SCIENTIST HAROLD ROBINSON

CODE ASSIGNMENT FOR V1:

01 = LAGASCEAE 0 2 = MELAMPODIEAE 0 3 - AMBROSIEAE 0 4 = ZINNIEAE 0 5 = VERBESINEAE 0 6 = COREOPSIDEAE 0 7 = GALINSOGEAE

CODE ASSIGNMENT FOR V2:

01 = MELAMPODIINAE 0 2 = ZINNIINAE 03 = ECLIPTINAE 0 4 = VERBESININAE 05 = HELIANTHINAE 0 6 = COREOPSIDINAE 0 7 = . .GALI,NSOGINAE 08 . - - AMBROSIINAE

CODE ASSIGNMENT FOR - V3:

ABROS I INAE MELAMPODIIlJAE MILLERIINAE MONTANOINAE RUDBECKIINAE ECLIPTINAE HELIANTHINAE GALINSOGINAE COREOPSIDINAE

(Contd ... 2)

CODE ASSIGNMENT FOR PROPERTIES WHICH ARE USED OTHER THAN MEAN VALUES (NUMERIC VALUES) :

FOR PROPERTY 21:

0 1 = ATTENUATE 02 = OBTUSE 0 3 = ACUTE 04 = ROUNDED

FOR PROPERTY 22:

01 = ROUNDED 02 = ACUTE 0 3 = DECURRENT 04 = HASTATE 0 5 = SAGITTATE

FOR PROPERTY 23:

01 = SERRATE 02 = ENTIRE 0 3 = DENTATE 04 = CRENATE

FOR PROPERTY 24:

0 1 = CORIACEOUS 02 = CHARTACEOCS 0 3 = MEC4BRANACE:OUS

FOR PROPERTY 2 5 :

0 1 = MODERATE 0 2 = STOUT 0 3 = MASSIVE

FOR PROPERTY 26:

01 = LOOPED 0 2 = 1NTRAMARGI:NAL STRAIGHT VEIN

FOR PROPERTY 27 :

01 = ACRODROMOLIS , PERFECT, BASAL 02 = ACRODROMOUS, PERFECT, SUPRABASAL 0 3 = SEM1CRASPE:DODROMOUS 04 = ACTINODROPIOUS , PERFECT, B A S S 0 5 = ACTINODROMOUS, PERFECT, SUPRABASAL

FOR PROPERTY 28:

01 = OVATE 02 = ELLIPTIC 03 = OBLONG 04 = OB-LANCEOLATE

FOR PROPERTY 29:

CUNEATE TRIANGULAR ELLIPTIC OBOVATlE TRIANGULAR OBLANCEOLATE OBCORDllTE OBLONG LINEAR SLENDER TUXBINATE

FOR PROPERTY 30:

01 = BLACK 0 2 = YELLOW 0 3 = BROWN

FOR PROPERTY 31:

01 = FIMBRIATE CUP 0 2 = STRAIGHT DIdEXGEIJT SPINES 0 3 = EPAPPOSE 04 = SCALES ~~ -

05 = CHAFFY TEETH 0 6 = BRISTLE,S 07 = AWNS

FOR PROPERTY 32:

0 1 = RETICULATE 02 = HOOKED HAIRS 03 = SLIGHTLY RIDGED 04 = STRIATE 0 5 = TUBERCULATE 0 6 = CRACKED 07 = ROUGH 0 8 = MOSAIC-PATTERN 09 = MAMMILA'TE 10 = GRANULXR 12 = PUBESCEI!TT

D E N D R J G X A F . 1 U S I P J S A V E ? A G E L i V K A G E C h ' I T i - I I ! * G R O U P )

A E S C A L Z S C I S T A k C E C L U S T E R E O M 3 I N E

C A S I L A B E L S F C

O E N D R O G R A H U S I N G C O M P L E T E L I N K A S E

R E S C A L E O D I S T A N C E C L U S T E R C O M 3 I N E

Fig. 28

O E N J 2 0 G 2 A i d U S I N G C i > t T R C I ! J M E T H a D

R E S C A L i D C I S T A N C E C L U S T E R C O M B I N E

C A S E

L A 3 Z L S F ^ ,

O E N U 2 U G R A M U S I N G M E U I A N M E T H O O

R E S C A L E O D I S T A N C E C L U S T E R C O M 3 I N E

C A S E 0 5 I0 1 5 2 0 ? 5 L A d E L +---------+------.---+---------+---------+---------+

P R E C E D i N G T A S K R E Q U I R E S 2.09 S E C O N O S C P U T I M E : 3 3 - 1 9 S E C O N D S E L A P S E D .

Fig. 30

vii. classification of the tribe a numerical...

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