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P1. Syst. Evol. 132, 279--298 (1979) Plunt ystemuti(snnd Euolution by Springer-Verlag 1979

From the Department of Vegetable Crops,University of California, DavisEvolution of Mating Systems in

L y c o p e r ~ h i r s u t u m as Deduced from Genetic Variationin Electrophoretic and Morphological Characters

ByCharles M. Rick, Davis, Jon F. Fobes, East Lansing,

and Steven D. Tanksley, Davis(Received August 8, 1978)

Key Words: Lycopersicon hirsutum, Solanaceae.--Allozymes, elinat varia-tion, electrophoresis, evolution of mating systems, isozymes, self-incom-patibility.

Abstract: Populations in the central part of the distribution are mostly self-incompatible and tend to be highly variable for allozymic and morphologicalcharacters ; those in the north and south limits are entirely self-compatible andtend to be genetically highly uniform. Gradations in variability are observed inthe intermediate regions. Flower size tends to diminish in the peripheral areas.The extensive differences in genotype observed between the north and southmarginal populations are not compatible with the concept of a single origin ofself-compatibility, but suggest, along with other evidence, that the substitutionof different alleles resulted from differentiation in the marginal areas fromolder, self-incompatible stocks of the central region. The conclusions regardingpatterns of genetic variation and nature of evolution of mating systems inL. hirsutum conform to a remarkable extent with those reached previously forL. pimpinellifolium, a species that is distinct in morphology and ecologicalpreferences yet has a similar latitudinal distribution.

Amon gst the tom ato species, Lycoper~'icon hi rsu tu m HUMB. & BONPL.is the most robust in growth and develops the showiest floral displays;high rates of insect cross-pollination might therefore be expected. Inthis respect it is the antithesis of the d imin utiv e an d smaller floweredL. pimpinell i fo l ium (JusL.) ~[ILL, a species with similar geographicdistribution. They are almost identical in latitude range but differ in theirelevation preferences in western E cua dor and Peril. The latt er grows incoastal areas, the former prefers higher e levations (1,500-3,000 m) in the

18"

037S-2697/79/0132/0279/$ 04.00

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280 C.M. RIcK et al. :A n d e a n v a l l e y s , e x c e p t i n E c u a d o r w h e r e i t a l s o s p r e a d s i n t o t h ec o a s t a l l o w l a n d s a n d i s s y m p a t r i c w i t h t h e f o r m e r .

A s t u d y o f g e n e t ic v a r i a t i o n i n L. hirsutum s h o u ld t a k e n o t e o f t h es u b s p e c i f i c t a x o n f . glabratum (C. H . MU LL.)1. MULLER (1940) de l in a te st h i s v a r i a n t i n t e r m s o f a g e n e r a l r e d u c t i o n i n h a i r in e s s o f s t e m s a n dl e a v e s, v e r y m u c h s m a l l e r (2 c m ) c o r o l la , a n d m o r e s l e n d e r c a l y x , b u t ,o b s e r v i n g in t e r g r a d e s w i t h t h e t y p i c a l f o rm , r e l e g at e s i t t o t h e c a t e g o r yo f a f o r m 1. I n o u r s t u d y o f t h e s p ec ie s , w e c o u l d n o t f a i l t o b e i m p r e s s e dw i t h t h e d i s t i n c t n e s s o f t h e E c u a d o r e a n a c c es s io n s in r e sp e c t t o t h e i rs m a l l e r fl o w e r s iz e, m o r e d i m i n u t i v e p l a n t p a r t s , a n d g e n e r a l r e d u c t i o ni n h a i r in e s s . I n t h e a v a i l a b l e a c c e s s io n s , i n t e r g r a d a t i o n w i t h t h e t y p i c a l

f o r m a p p e a r s o n l y in t h e H u a n c a b a m a r e gi o n o f P e ri l, w h e re t h eu n i q u e , m o n o g e n i c a l l y d e t e r m i n e d , q u a l i t a t i v e l y d i s t i n c t h v a r i a n te x i s ts . A l t h o u g h l a rg e e p i d e r m a l h a i r s ar e r e d u c e d t o a g r e a t e r e x t e n t int h e l a t t e r b i o ty p e s t h a n i n E c u a d o r e a n glabratum, t h e y d o n o t f i tMULLER'S co nc ep t o f glabratum i n r e s p e c t t o f l o w e r s iz e , c a l y x , o r o t h e rc h a r a c t e r i s t i c s . I n v i e w o f t h i s c o n f u s i o n i n c o n c e p t s a n d m i s i d e n t i f i c a -t i o n o f m a n y h e r b a r i u m s p ec im e n s , w e sh a ll n o t a t t e m p t t o d i s t i n g u is ha n y s u b s p ec i fi c t a x a , b u t r e fe r o n l y t o E c u a d o r e a n v s. P e r u v i a nhirsutum.

S e l f - i n c o m p a t i b i l it y o f t h e P e r u v i a n hirsutum w a s d i s c o v e r e d b yM c G UtR E a n d R I C K (1 95 4) a n d i t s d i s t r i b u t i o n a n d i n h e r i t a n c e w e r ei n v e s t i g a t e d b y M A R TIN (1 96 3). T h e s p e c i e s h a s b e e n r e c e i v i n g c o n -s i d e r a b l e a t t e n t i o n f o r i ts p o t e n t i a l v a l u e a s a s o u r c e o f g e n e s f o r d is e a s er e s i s t a n c e a n d p a r t i c u l a r l y f o r i n s e c t r e s i s t a n c e , p o s s i b l y c o n d i t i o n e db y t h e s t r o n g , u n p l e a s a n t ( to m o s t h u m a n s u b je c t s) p u n g e n c y o f i tsherbage (STONER1 9 7 0 a n d u n p u b l i s h e d ) .

O u r s t u d y o f a l lo z y m e v a r i a b i l i ty i n L. pimpinellifolium (RICK & al .1 97 7) r e v e a l e d i m m e n s e d i f f e r e n c e s i n g e n e t i c v a r i a b i l i t y a s m e a s u r e db y s e v e r a l c r i te r i a b e t w e e n t h e o b s e r v e d m a x i m a i n N W . P e r d a n d t h em i n i m a i n th e n o r t h e r n a n d s o u t h e r n m a r g i n s o f i ts r an g e . H i g hp o s i t iv e c o r r e l a ti o n s w e r e d e t e r m i n e d b e t w e e n t h e e x t e n t o f g e n e t icv a r i a b i l i t y , r a t e s o f c ro s s - p o l l i n a t io n ( C P ), f l o w e r si ze , a n d d e g r e e o fs t i g m a e x s e r ti o n . O u r s u b s e q u e n t s t u d y o f c r o s s- p o ll in a t io n i n a t e s tp l o t i n S . P e r i l ( R IC K & a l . 1 9 78 ) a s c e r t a i n e d t h a t t h e r e l a t i o n s h i p s w e r es t r o n g e r w i t h fl o w e r s iz e t h a n w i t h s t i g m a e x s e r t io n , a n d d e m o n s t r a t e dt h a t i n t e r r e g i o n a l d if fe r e n ce s in C P w e r e i n f l u e n c e d le ss b y p o p u l a t i o nd y n a m i c s o f t h e p o l l i n a ti n g b ee s a n d o t h e r e n v i r o n m e n t a l f a c to r s t h a nb y h e r e d i t a r y v a r i a b i l i t y in f lo r a l t r a i t s o f t h e h o s t p l a n t . O n t h e b a si s

1 L y c o p e r s i c o n h i r s u t u m HUM B. ~5 BONPL. f. g l a b r a t u m (C.H.MuLL.) RICK,FORES & T AN KS LEY .- -Bas ionym : L . h i r s u t u m v a t . g l a b r a t u m MULLER, U.S . D ep t .A ttic . M isc. Pu bl. 382 (1940).

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Mating Systems in Lycopersicon hirsutum 281o f t h e se f a c t s, t h e o b s e r v e d p a t t e r n s o f v a r i a b i l i t y i n L. p impinel l i -f o l i u m c ou l d be i n t e r p r e t e d a c c o r d i ng t o t he f o l l ow i ng r a t i ona l e . T her e g io n o f h i g h e st v a r i a b i l i t y r o u g h l y a p p r o x i m a t e s t h e h y p o t h e t i c a lr e g i on o f o r ig i n , h i gh va r i a b i l i t y a n d ou t e r o s s i ng be i ng c h a r a c t e r i s t i c o ft he a nc e s t r a l s pe c i e s a nd be i ng s e l e c t i ve l y a dva n t a ge ous i n t ha t r e g i ono f g r e a t e c o log i c al d i ve r s i t y . A s t he s pe c ie s s p r e a d no r t h a nd s ou t h ,va r i a b i l i t y d i m i n i s he d a s a r e s u lt o f ge ne ti c d r i f t a nd s e l ec t ion f o r al i m i t e d nu m be r o f h i gh l y s uc c e ss f u l, p r o l if i c ge no t ype s . F i x a t i on o f t hel a t t e r g e n o t y p e s w a s e x p e d i t e d b y s e le c ti o n f o r f lo r al s t r u c t u r e m o d i fi -c a t i o n s t h a t p r o m o t e i n b r e e d i n g .

T h e a f o r e m e n t i o n e d o b s e r v a t i o n s a n d d e d u c t i o n s s t i m u l a t e d as i m i l a r s t u d y o f L. h irsutum to a s c e r t a in t o w h a t e x t e n t i f a n y s i m i la rr e l a t i ons h i p s m i g h t ho l d i n a spe c ie s o f ne a r l y i de n t i c a l ge og r a ph i cd i s t r ib u t i o n , y e t r a d i c a ll y d if f e re n t m o r p h o l o g y a n d n a t u r a l b r e e d i n gs y s t e m . A s m e n t i o n e d a b o v e , t h e f l o w e r i n g o f L. h irsutum i s va s t l ym o r e s h o w y t h a n t h a t o f L. pimpinell i folium. The two spec ies a l so di f fe rm a r k e d l y i n r e s p e c t to t h e h e a v y , r o b u s t c h a r a c t e r o f t h e f o r m e r i nc on t r a s t t o t he d a i n t y , s l e nde r pa r t s o f t he l a t t e r , r a d i c a l d i f fe r e nc e s i nf o l ia ge vo l a t il e s , a nd o t he r phys i o l og i c a l c ha r a c t e r i s ti c s . P os s i b l y t hem o s t p r o f o u n d d i ff e re n c e af f e ct i n g p o p u l a t i o n s t r u c t u r e is t h e p r e v a i l -i ng s e l f - c om pa t i b i l i t y o f L. p impine l l i fo l ium a n d t h e a f o r e m e n t i o n e ds e l f - in c o m p a t i b i l i t y o f t h e m a j o r i t y o f t h e hirsutum access ions .

Materials and MethodsOu r study was m ade on 52 living accessions of L. hir.sut'um scattered over theentire known range of the species (Table 1, Fig. 2). Voucher specimens are kept inherb ariu m of C. M. Rl('K.--T his material suffers the following shortcoming s tbra stud y of genetic variab ili ty: 1) a few collections were mad e witho ut adeq uaterecords; 2) seeds of certain accessions have been regenerated in various, oftenunspecified, proced ures since the original collections were made ; and 3) na tur alpop ulation s ten d to be small (each often limited to five plants o r less). Samp lingwas further l imited b y the lack of r ipe frui t on certain plants . Acknowledgingsuch shortcomings, we nevertheless deemed i t sufficiently impo rtant to conductthe investigations, since future opportunities for acquiring superior materialare highly uncertain. The avai lable information concerning the nu mb er of wildplan ts sampled~ the gen eration of the seeds used in the s urv ey (when know n),and other pert inen t po pulat ion p aram eters is presented in Table 1.General observat ions were made on gross morph ology of at least one cul tureof each accession. Exc ept for the monogenic hair character h, these da ta are notincluded in Table 1.Allozyme variat ion for acid phosphatase (Aps), esterase (Est), glu t ama teoxMoacetate t ransaminase (Got)and peroxidase (Prx) system s was analyzed bystandard methods for horizontal slab starch-gel electrophoresis. Details con-cerning th e meth odo logy are given by RICK & FOBF,S (1975a), RICK & al. (1976),and RICK & al. (1977). A stan dar d nu mb er o f sixteen individuals w as ado ptedfor sampling the proge ny of each wild plant .

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282 C .M . ~]CK e t a l . :E m p i r i c a l i m p r o v e m e n t s i n t h e e st e r a se a c t i v i t y s t a i n r e v e a le d a n u m b e r o fn e w b a n d i n g p h e n o t y p e s c o n t r o l le d b y s e v e r a l lo ci i n a d d i t io n t o Est-1. T h e s ei m p r o v e m e n t s i n c l u d ed : 1) u s in g ~ - n a p h t h y l b u t y r a t e a s t h e e n z y m e su b s t r a te

r e p l a c in g p r e v i o u s l y u s e d ~ - n a p h t h y l v a l e r a t e a n d 2 ) m o d i f y i n g t h e p H o f t h es t a i n i n g s o l u t io n t o p H 6 . 0 u s i n g 0 .1 M s o d i u m p h o s p h a t e b u f f er . ~ - n a p h t h y lb u t y r a t e w a s p r e p a r e d a s a 1~o s o l u t i o n i n 1 00 ~o a c e t o n e a n d u s e d a t a r a t e o f5 m l p e r 1 00 m l s t a i n i n g s o l u t io n . T h e s t a i n i n g s a l t w a s F a s t B l u e R R S a l t( S i g m a ) a t 0 . 1 g p e r 1 00 m l s o l u t i o n . I t w a s a l s o p o s s ib l e t o a n a l y z e v a r i a t i o n a tt w o p h o s p h o g l u c o m u t a s e (Pqm) l o ci u t il i z in g t h e f o l l o w i n g s t a i n i n g r e c i p e :3 5 0 m g g l u c o s e - l T h o s p h a t e ( d is o di u m s al t) ; 8 m g N A D P ; 2 0 m g M T T ; 1 .5 m lM g C le ( 1~ o a q u e o u s s o l. ); 5 m g P M S ; 3 5 u n i t s g l u c o s e - 6 - p h o s p h a t e d e h y d r o -g e n a s e ; 7 5 m l 0 .1 M T r i s, p H 8 .0 . T h e r e s u l t s o f th e s e a d d i t i o n a l t e s t s a r e n o tp r e s e n t e d i n T a b l e 2 b u t a r e m e n t i o n e d i n a p p r o p r i a t e p l a c es in t h e Resultss e c t i o n b e c a u s e i t w a s n o t p o s s i b l e t o a p p l y t h e m t o a l l a c c e s s i o n s .R e a c t i o n t o s e l f - p o l l i n a t io n w a s d e t e r m i n e d f o r a l l a c c e ss i o n s. S i x o r m o r ef l o w e r s o n e a c h o f s i x o r m o r e p l a n t s p e r a c c e s s io n w e r e a r t i f i c i a l l y se lf -p o l l i n a t e d i n a n i n s e c t - f r e e g r e e n h o u s e . S i b p o l l i n a t i o n s w e r e m a d e a s c o n t r o l s .T h e p r o p o r t i o n o f f lo w e r s s e t t i n g f r u i t c o u l d b e r e a d a c c u r a t e l y t w o w e e k s a f te rp o l l i n a t i o n , a n d r e l a t i v e s e e d y i e l d s w e r e a p p a r e n t t w o m o n t h s l a t e r .I n t h e c o u r s e o f o u r c o l l e c ti n g L. h i rsu tum, w e m a d e o b s e r v a ti o n s o f th ei n s e c t p o l l i n a t o r s o f t h i s s p ec i es . U n f o r t u n a t e l y , t r a v e l s c h e d u l e s s e ld o ma l lo w e d o p p o r t u n i t y t o v i si t e a c h w il d p o p u l a t i o n a t t h e o p t i m u m t i m e f o r s u c hp u r p o s e s - - i n f a c t, i n th e m a j o r i t y o f s it es n o s u ch a c t i v i t y w a s o b s e rv e d .

S e l f - In c omp at ib i l i t yR e a c t i o n s t o t h e p o l l in a t i o n s t o t e s t s e l f - c o m p a t i b i l i t y r e a c t i o n s

w e r e g e n e r a l l y de c is iv e a n d f e l l i n t o o n e o f t w o c a t e g o r i e s ~ i t h e r t h es e l ls f a i l ed t o s e t a n y f r u i t o r t h e y r e s u l t e d i n f r u i t s e t t i n g a n d s e e dp r o d u c t i o n e q u i v a l e n t t o t h o s e o f s ib p o l l i n a t io n s . T h i s c le a r - c u td i f f e r e n c e p e r m i t t e d s i m p l e c l a s s i f ic a t io n i n t o s e l f - c o m p a t i b l e (S C ) o rs e l f - i n c o m p a t i b l e ( S I ) c a t e g o r i e s , a s in d i c a t e d i n T a b l e 1. W h e r e a s i tw a s k n o w n p r e v i o u s l y t h a t t h e E c u a d o r e a n a c c es s io n s ar e s e lf -c o m p a t i b l e , o u r s u r v e y al so r e v e a l e d t h a t t h e s o u t h e r n m o s t p o p u l a -t i o n s c a n a ls o r e p r o d u c e b y s e lf - p o l l i n a ti o n . F u r t h e r a s p e c t s w i l l b ed i s c u s s e d la t e r i n r e l a t i o n t o p o p u l a t i o n v a r i a b i l i t y .

N a t u r a l P o l l in a t i o nO u r c o l l ec t iv e o b s e r v a t i o n s o n n a t u r a l p o l l i n a to r s o f L . h i r s u t u m

s u g g e s t t h a t t h e t i m e o f g r e a t e s t a c t i v i t y i s i n t h e m i d - t o la t e m o r n i n g ,c o r r e s p o n d i n g t o t h a t f o r L . p i m p i n e l l i fo l i u m ( R IC K & a l . 1 9 7 8 ) . W h e n i tw a s p o s s i b l e t o v i si t p o p u l a t i o n s a t t h a t t i m e ( L A 1 2 64 , 1 29 5 , 13 4 7, a n do t h e r s i t es f r o m w h i c h v i a b l e s e ed s w e r e n o t a v a i l a b le ) , t h e i n t e n s i t y o fb e e v i s i t a t i o n s w a s i m p r e s s i v e . F l o w e r s o f e a c h p l a n t i n t h e p o p u l a t i o nw e r e v i s it e d b y a w i de a s s o r t m e n t o f s pe c ie s o f B o m b i n i d , A n d r e n i d ,C o l le t i d , M e l ep o n i d , a n d X y l o c o p i d b e e s. F r o m t h e a r r a y o f p o l le nt y p e s s e en o n t h e c o l l e c te d s p e c im e n s i t a p p e a r e d t h a t t h e m a j o r i t y o f

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Mating Systems in Lycopersicon hirsutum 283bees were forag ing d i f fe ren t p lan t spec ie s in po ly lec t ic f a sh ion . S incet h e d a t a t h u s c o ll e ct e d w e r e m e a g re a n d c o u l d be t a k e n f r o m o n l y as m a l l f r a c t i on o f t he t o t a l pop u l a t i on s c o l le c t ed , t he de t a i l s a r e no tp r e s e n t e d he r e .

Electrophoretic CharactersR a t iona l e . E l e c t r ophor e t i c va r i a t i on i n t h i s s pe c i e s w i l l be c ha r a c -

t e r i z e d a s e xp l a ine d be low . I n c on t r a s t t o ou r p r e v ious s t ud i e s onL. cheesmani i (RICK~5 FOBES 1975 a), L. esculentum (RICK& FOBES1975 b), th e " m i n u t u m co m pl ex " (RICK & a l. 1976) , an d L. p impine l l i -

f o l i u m (RICK & a l. 1977), the inh e r i t a nce of zy m ot yp ic va r ia t i on was no ts t ud i e d i n p r oge n i e s f r om c on t r o l l e d c r os s e s w i th in L . h i r s u t u m or inc r os se s w i th s t a n da r d escu l en tum l ine s i n o r de r t o c l a r if y i nhe r i t a nc e o fva r i a t i ons . I t w a s ne ve r the l e s s c l e a r f r om c e r t a in p r oge n i e s o f w i ldp l a n t s t ha t t he va r i a n t ba nds s e e n r e p r e s e n t e d a l t e r na t e a l l e l e s a t ag ive n loc us . T he r e s u l t s c l e a rl y de m o ns t r a t e d t ha t , w i th pos s ib l ee xc e p t i on s i n pe r ox ida s e s , t he l oc i ba nd s a pp e a r i n t he s a m e pos i t i ons i n

L . h i r s u t u m a s t he y d o i n t he a f o r e m e n t ion e d s pec ie s. T he e x c e p t i ons i npe r ox ida s e s a ppe a r t o be a dd i t i ona l l oc i i n L. h i r su tum. I n a s m u c h a sa ll el es c ou ld no t be m a t c he d c on f ide n t l y w i th t hos e o f t he o the r s pe ci es( e x c e p t f o r t h e n o r m a l escu l en tum + a l le le s r epresented a s cont ro l s one ve r y ge l) , t he va r i a n t s a r e a r b i t r a r i l y de s igna t e d by pos i t i ons w i thr e f e r e nc e t o t he + ba nds . T hus , a n a l l oz ym ic ba n d t h a t is a dv a nc e d5 m m be y on d t he pos i t ion o f t he + ba n d i s l a be ll e d "a 5 " ; one t h a t isr e t a r d e d 2 r a m , " r 2 " , e t c . I n t h i s f a s h i o n w e a r e n o t c o m m i t t i n gour s e lve s t o t he e xa c t i de n t i f i c a t i on o f a ll el es . T h i s c o ns e r va t i vea t t i t ud e i s a ls o m a in t a ine d i n r e ga r d t o a l l oz ym e s o f ve r y s im il a rphe no type : w e do no t d i s t i ngu i s h be tw e e n a l l e l e s un l e s s pos i t i onsd i f fe r e d b y a t l e as t 2 m m o r o t h e r s t r o n g e v i d e n c e o f p h e n o t y p i cd i f f e r e nc e ob t a ine d .

T h i s s ys t e m i s una m b iguo us f o r a ll loc i e xc e p t P r x - 4 . A c c or d ing t oou r p rev iou s e xp er ie nce (RICK & FOBES 1976) , this locus c odes for ac o m p l e x o f b a n d s i n b o t h a n o d a l a n d c a t h o d a l a r r a y s . A c c o r d i n g l y w eh a v e a p p l i e d a r b i t r a r y c a p i t al l e t t e r s y m b o l s t o m o s t o f t h e v a r i a n ta l le les of th i s locus , the ke y to w hich app ea rs in F ig . 1. He re aga in , wedo no t r e c ogn i z e ne w a l le le s un l es s t he i r ge l ph e no typ e s a r e une qu ivo -c a l l y d i f f e r e n t . T h i s c o n s e r v a t i v e a t t i t u d e u n d o u b t e d l y r e s u l t s i n t h ene g l e c t to a c e r t a in e x t e n t o f t he n a tu r a l l y oc c u r r i ng va r i a b i l i t y . 'Am or e e x t e ns ive a na lys i s o f s e g r e ga t i ng ge ne r a t i ons w i th in L . h i r s u t u ma n d b e t w e e n i t a n d s t a n d a r d escu l en tum l i ne s w ou ld no doub t a i d i nde l i ne a t i ng a dd i t i on a l a ll el es , a nd a pp l i c a t i on o f m or e r e f i ne d e le c-t r o p h o r e t i c t e c h n i q u e s w o u l d p r o b a b l y u n c o v e r m o r e v a r i a t i o n , a s i t

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284 C.M. RICK ct al. :Table 1. Summar y of collection data, compatibility reaction,

Access.No. Dept. orSite of collection provinceEcuadorLA 16241625407126412661223125512521253Peru

17381739173717361740171717181741139138638713521353135413471775C13611775F1362178017791778177713931366129817611559941764177215581295

Jipijapa ManabiJipijapa ManablGuay aquil: E1 Mirador GuayasBucay ChimborazoPallatanga ChimborazoAlausi ChimborazoLoja : Pedestal LojaLoja: Jard ln Botanico LojaPueblo Nuevo Loja

R. Piur a: Desfiladero Piur aW. of Canchaque Piur aCashacoto PiuraPucutay PiuraW. of Huanc abam ba PiuraR. Hua nca bam ba: Sapalache PiuraPiuraSondorillo PiuraR. Utc uba mba : Corral Quemado AmazonasCajamarca: Inca Baths CajamarcaSanta Apolonia CajamarcaR. Jequctcpeque: Rupe CajamarcaContumaz~ CajamarcaR. Chicama: N. of Cascas CajamarcaR. Moche: Empa lme Otusco La Libert adR. Casma: 61k in fr. Carr. Panam. Ancash

Pariacoto Ancash71 km fr. Carr. Panam. AncashChacchan Ancash76 km ft. Carr. Panam. Ancash85 km fr. Carr. Panam. Ancash92 km fr. Carr. Panam. Ancash97 km fr. Carr. Panam. Ancash97 km fr. Cart. Panam. AncashR. Fortal eza: Cajacay AncashR. ChillSn: Yaso LimaE. of Y a s o LimaE m p a l m e H u a m a t a n g a L i m a9 2 k m f r o m L i m a L i m aW . o f C a n t a L i m aW . o f C a n t a L i m aC a n t a L i m aR. Rimac: Surco Lima

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M a t i n g S y s t e m s i n L y c o p e r s i c o n h i r s u t u mand ha i r type fo r access ions o f L . h i r s u t u m

285

No. wi ldE l e v a t i o n p l a n t s(m) Col lec to rs So urce sam pled C o m p a t .r e a c t i o n H a i rt y p e

100 RC , H W Orig. ?100 RC, H W Orig. ?5 0 CR, M R I n c r . 1400 CR , M R Orig. 5800 CR , M R Orig. 11,800 TG , CR , M R Orig. 32 000 CR , M R Orig. 32,200 CR , M R Orig. 21,800 CR , M R Orig. 2

SCSCSCSCSCSCSCSCSC

+++++++++

900 CO1,100 RC , H W1,900 CO2,000 CO2,200 RC , H W27500 RC , H W2,500 RC, H W1,600 HW , RC1~000 M HC R , M RC R , M R2,100 CR, M R, EV2,650 M R, CR, EV2,300 CR , M R2,100 M R, CR, EV1,400 JF , EV1,500 CR , M R2,100 JF , EV2,200 CR , M R2,300 JF , EV2,700 JF , EV3,000 JF , EV3,20O JF , EV3,200 MH2,300 Cf~, M R1,600 CI~, M R1,700 JF , EV2,200 DB2,5OO CR , M R2,400 JF , EV2,600 JF , EV2,7OO DB2,000 CI~, M R, E V

Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.I n c r .I n c r .I n c r .Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.I n c r .Orig.Orig.Orig.Orig.I n c r .Orig.Orig.Orig.Orig.

S IS IS IS IS IS IS IS IS IS IS IS IS IS IS IS IS IS I

S IS IS IS IS ISCS IS IS IS I

+ / hh+/h+/h+/h++++++++++++++++++++++++++++

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286Tab le 1 ( con t i nued)

C.M. R~CK et al. :

Access. Dept. orNo. Site of collection province1753 70 km ft. Lima Lima1560 Matucana Lima1745 R. Cafiete: Putinza Lima1696 Huanchuy-Cacra Lima1695 Cacachuhuasin Lima1681 Mushka Lima1691 Yauyos Lima1730 R. San Juan : 78 km fr. C. Panam. Huancavelica1731 86 km ft. C. Panam. Huancavelica1721 R. Pisco: Ticrapo Viejo Huancavelica

DB =Da vid Baumann, RC = Raymond Clark, JF =J on Fobes, TG- -Tomas Guerrero, MH =Miguel Holle, DN--Daniel Nakama, CO =CarlosOchoa, CR=Charles Rick, MR=Martha Rick, EV=Eduardo Vallejos,HW = Harold Winters.

did in t he studies of SINGH (i976) and others on genetic var iati on inDrosoph i l a species.The only new locus recognized in this study, designated Prx-3b , isexpressed pheno typi call y by bands r etarde d at least 5 mm from theposition o f the n orma l allele of Prx -3 . We feel reasonably confidentabout this decision because variation at the two positions seems to beindependent. Other bands that might be coded by additional lociappear in positions more accelerated than Prx - 3 and between Prx - 3 andPrx -4 . Until sufficient evidence for separate loci has been obtained, weprefer to tre at these groups conserva tively as alleles of Prx - 3 and Prx - 4respectively; at any rate these variations have virtually no impact onthe results or conclusions.

Refinements in our procedures for esterases, outlined in the sectionon Methods , resulted in consistent staining o f addit ional bands, repre-senting at least five new loci not previously detected in other species.Since these impr oveme nts were effected during the course of theh i r s u t um investigations, they could not be applied to all accessions.Further, our experience with these variations has been too limited todiscriminate between alleles and loci. For these reasons, such data arenot included in Table 2, but are presented briefly in appropr iate placesbelow.Keeping in mind the aforement ioned limitations, let us consider thenatu re of the results, which are summari zed in Table 2. Regardi ng agenoty pic char acteri zation of the species as a whole, rath er few

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M~ting Systems in Lycopersicon hirsutum 287Table 1 (continued)

Elevat ion(m) Collectors SourceNo. wild

plants Compat . Hai rsampled react ion typ e2,100 JF , EV2,400 DB1,800 JF , EV2,100 DB1 ,900 DB2,450 DB2,9OO DB1,700 EV2,100 EV2~100 DB~ MH, D N

Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.Orig.

2 SI +1 SI +2 SC +1 SC +l SC +1 SC +1 SC +2 SC +4 SC +~. SC +

Orig. = Pr og en y fro m seed collected in wild ; Inc r. = f ro m seed increa,sed inculture ; SC = self-co mpatible ; SI = self-incom patible ; + /h = variable hairi-aess; + = uniformly hairy.

g e n e r a l i z a t i o n s c a n b e d r a w n . V a r i a b i l i t y b e t w e e n a n d w i t h i n p o p u -l a ti o n s a n d p a r t i c u l a r l y t h e r e p l a c e m e n t o f a ll el es f r o m o n e e n d o f t h ed i s t r i bu t i on t o t he o t he r ( c ons ide r e d be low ) a r e s om e o f t he p r o b l e m s o ft h e d y n a m i c a l l y ev o l v i n g s y s t e m t h a t o b s t r u c t s u c h a c h a r a c t e r i z at i o n .T he f o l l ow i ng p r e va i l i ng a l le le s a pp e a r t o be d i s t i nc t i ve i n L. hirsutum:Ap s- 1 re, Est-1 a2, a n d Got-4 as, a22, and ,24 . Mo s t t h e t h e Prx-4 al leles area l s o d i s t i nc t i ve , bu t t oo num e r ous f o r a ny s i ng l e a l l e l e t o t yp i f y t hes pe c ie s ( F ig . 1, T a b l e 2 ) . I n s o f a r a s ou r i nve s t i ga t i on s o f t he t om a t os pe c i e s ha ve p r og r e s s e d , t he s e a l l e l e s s e e m t o d i s t i ngu i s h L. hirsutumf r o m t h e o t h e rs . T h e e l e c t r o p h o r e t i c d a t a a r e t h e r e f o r e c o n s i s te n t w i t ht hos e o f g r o s s m o r pho l og i c a l c ha r a c t e r s i n unde r s c o r i ng t he d i s t i nc t i ve -ness o f L. hirsutum.

E xt e n t o f V a r i a b il i ty . Q ue s t i ons c onc e r n i ng t he k i nds o f a ll el es i nva r i ous p a r t s o f t he d i s t r i bu t i on w i ll be c on f r o n t e d be l ow . T he r e s u l t s o ft h e s u r v e y a r e s u m m a r i z e d in T a b l e 2 in a p p r o x i m a t e o r d er f r o m n o r t ht o s ou t h , a nd , w i t h i n a g i ve n l a t i t ud e ( f r om w e s t t o e a s t , i n P e r i l m os t l ya l o n g r i v e r d r a i n a g e s s i n c e t h e y p r o v i d e t h e o n l y h a b i t a t s ) .

T h e d e g r ee o f v a r i a b i l i t y i s e x p r e s s e d s i m p l y i n t e r m s o f t h ep r o p o r t i o n o f l oc i t h a t a r e p o l y m o r p h i c p e r a c ce s si o n. F o r t h e f o ll o w in gr e a s o n s t h e d a t a d o n o t p e r m i t t h e d e r i v a t i o n o f s u c h o th e r , m o r ep r e c i s e m e a s u r e s a s pe r c e n t he t e r oz y go s i t y o r f r e qu e nc y o f a ll el es pe rl ocus , e t c. in e a ch a c c es s ion . 1) T h e s m a l l nu m be r o r un kn ow n nu m be ro f p l a n t s p e r p o p u l a t i o n is u n s a t i s f a c t o r y f o r e s t i m a t i n g s u c h p a r a m -e t e r s . 2 ) I n s u f f i c i e n t p r oge ny p l a n t s w e r e s a m p l e d t o j u s t i f y e s t i -

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288 C.M. RICK et al. :Table 2. Sum mary of kinds of allel~

Access.No. Ap s- 1 Ap s- 2 Est- 1 Got-1 Got-2 Got-3 Got-4EcuadorLA1624 ~ ~ a2 + a20 a81625 ~ ~ a2 + a20 + a8407 r4 + a2 + a20 + a81264 a5 + ~ + a20 + a81266 ~ + ~ + a20 + a81223 r2 + a2 + a20 + a81255 r2 + a2 + a20 + a81252 ~ + ~ a2 a20 + a81253 ~ + ~ a2 a20 + a8Peru

1738 ~ ~ a2 + a15 + a81739 ~ ~ a2 + alO + +1737 ~ ~ + , a 2 a2 a10, a15 + +1736 ~ ~ a2 + a15? + a81740 ~ ~ a2 + , a 2 alO, n + a8, a221717 +, n +, n, a4 +, r4 +, n a20 + a8, a221718 +, a5 , r2 + a2 + , n alO, a20 + a8, a221741 ~ ~ a2 + alO + +1391 r12 + a2, a67 + a8 + a8386 r4 a4 a2, a6 + ~ +387 r4 ad a2 + ,a 5 a8 + a81352 ~ ~ a2 + a8, a20 + a8, a221353 r4 +, a5 + , n + a8, a20 + a8, a221354 r4 +, a5 +, a2 , n + a8, a20 + a81347 r4 +, a5 +, a2 + a8, a20 +, a2 a8, a221775C r2, r4 +, a5 +, a2 +, a2 a8 a2 a81361 r4 +, aS a2 a2 a8 +, a2 a81775F r2, r4 +, a5 +, r2 a2 a8 a2 a8, a241362 r2, r4 + , a 5 a2 a2 a8 a2 a8, a241780 r2 + ,a 5 a2 a2 a8 a2 a8, a221779 r2, r4 a5 + , a 2 a2 a8 a2 a8, a221778 r2, r4 +, a5 +, a2 +, a2 a8 a2 a8, a221777 r2,r4 +, a5 +,a 2 a2 a8 a2 a8, a241393 r2, r4 + , a 5 a2, a5 a2 a8 a2 a8, a241366 r2, r4 a5 + , a 2 + a8 + a81298 r2 a5 ~ + , a 2 a8 a2 a241761 r2 a5 a2 + a8 a2 a221559 r2 a5 a2 a2 a8 a2 a2294 r2 a5 a2 + a4, a20 + a8, a221764 r2, n a5 a2 + , a4 a8 a2 a221772 r2, n a5 a2, a4 +, a4 a8 +, a2 a221558 r2 a5 a2 a2 a8 a2 a221295 r2 a5 ~ ~ a8 + a8

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M a t i n g S y s t e m s i n L y c o p e r s i c o n h i r s u t u m, t e e t e d i n a c c e s s i o n s o f L . h i r s u t u m

28 9

~ x-I P r x - 2 P r x - 3 P r x - 3 b P r x ~ 4 P r x - 7 a P r x - 7%

p o l y m o r p h i cloc i

;1 + + n A + +,1 + + n A + +4 + + n C + +,1 + + n A + +1 + + n A + +1 + + n D + +1 + + n A + +1 + + n A + +1 + + n A ,B + +

1, r2 + + r5 , r7 , n 1 a lle le + +1 + + r5, n A , B + +1, r2 + + r3 2 alle les + +1, r2 + + r5 2 a l le les + , a 2 +1, r2 + + r5 + , B + , a 2 +1 , r 2 + + , a 3 r S, n + , A , B + , a 2 +1 + + , a 3 r S , n + , A , B + , a 2 +1 + + , a 5 r 5 , n 2 a lle l es + +1, r2 + + , a5 n A + 1I + + n A + +1 + + n + ,B + +1 + + r3 A , B + +1 + , r 2 + n , r 3 B , C , D + +1 , r 2 + , r 2 + n + , A + , n +I , r 2 + , r 2 + n , r 3 B , C , D + , n +1 + + n A + +1 + + ,a S n B + +1 + + n A + +l + , r 2 + n B + , n +l + , r2 + n B + +1 + + n B + +l + , r2 + n B + +l + + n A + +I + + n B + +, r2 + + rS , n C + , n +l + + r 5 , n + , A , C + , n +l + + n A + +[ + + n C + +l + + r5 C + +l + + rS, r7 A + +l + + n A + , a2 +l + + n C + ,n +[ + + r5 C + +

171733175 072572521

814175050722921293621214329292929

0014

2136

70

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290 C.M. 1%~c~:et al. :Ta ble 2 ( conti~tued )

ACCESS.No. Ap s - 1 Ap s - 2 Es t - 1 Go t- 1 G o t -2 Go t - 3 Go t - 4

1753 n a 5 a 2 + , a 2 a 8 , a 2 a 81560 r2 , n a5 a2 a2 a8 + a81745 r5 a5 a2 a4 a8 + a81696 r2 a5 a2 a2 a8 + a41695 r2 a5 a2 a2 a8 + a41681 r2 a5 a2 a2 a8 + a41691 r2 a5 a2 a2 a8 + a41730 ~ ~ a2 a4 a8 + +1731 ~ ~ a2 a4 a8 + a81721 r 2 a 5 a 2 + , a 2 a 8 + a 8

m a t io ns o f a ll e le f r e que nc ie s . A c c or d ing ly , t he s i t ua t i on a t e a c h l oc us isi n d i c a t e d b y t h e n u m b e r o f k i n d s o f a ll el es . T h e m i n i m u m p r o p o r t i o n o fa ll el e f r e q ue n c y f o r po ly m or p hy w a s s e t a t 5~o . A s ing le va lue , pe r c e n to f l oc i t ha t w e r e po lym or ph i c , w a s de r i ve d f o r e a c h a c c e ss ion . D e s p i t ethe c r ude ne s s o f t h i s c r i t e r ion , h igh ly s i gn i f i c a n t t r e nds i n the d a t a w e r et h e r e b y d e t e c t e d . F u r t h e r , t h e h i g h e r t h e p o l y m o r p h y , g e n e r a l l y t h eh i g h e r t h e p r o p o r t i o n o f p r o g e n y p l a n t s t h a t w e r e h e t e r o z y g o u s a t t h epo lym or ph i c l oc i .

T h e m o s t d r a m a t i c f e a t u r e o f t h e r e s u l ts i s t h e c o n t r a s t b e t w e e n t h ez e ro o r n e ar - ze r o l ev e ls o f p o l y m o r p h y a t t h e n o r t h a n d s o u t h m a r g in so f t he d i s t r i bu t i on a nd t he m u c h h ighe r l eve ls i n t he m or e c e n t r a lreg ions . An i r regula r c l ine can be de tec ted f rom the ve ry low leve l s inthe s ou th t ow a r d h ighe r l e ve l s i n t he c e n t r a l r e g ion , un t i l m a x im umv a l u e s a r e r e a c h e d i n t h e P i u r a - L a L i b e r t a d - C a j a m a r c a a r e a , w h e n c ethe pe r c e n t a ge s de c li ne r a p id ly no r thw a r d . T he s e a s pe c ts o f va r i a b i l i t ya r e e v ide n t i n t he g r a ph i c a l s u m m a r y o f r e s u l t s in F ig . 2 . T he r e s u l t sc o r r e l at e r e m a r k a b l y w i t h t h e g e o g r a p h i c d i s t r i b u t i o n o f g e n e ti c v a ri -a b i l i t y obs e r ve d i n L . p i m p i n e U i f o l i u m (RICK & al. 1977).

T h e n e x t n o t e w o r t h y i t e m i s t h e r e l a t i o n s h i p b e t w e e n t h i s g e o -g r a p h i c d i s t r i b u t i o n o f g e n e ti c v a r i a t i o n a n d c o m p a t i b i l i t y r e a c t io n s :t he r e g ions o f l ow e s t va r i a b i l i t y a r e a s s oc i a t e d w i th SC, t hos e o f h ighe rva r i a b i l i t y , w i th S I ( F igs . 2 , 3 ). W i th in t he r e s t r i c t i ons o f t he nu m b e r o fa c c es s ions a va i l a b l e fo r t e s t ing , t he b ou nd a r y be tw e e n t h e no r th e r n SCr e g ion a nd t he c e n t r a l S I a r e a c o r r e s ponds e xa c t l y w i th t he f r on t i e rbe tw e e n E c ua do r a nd Pe r i l. T o t he s ou th , SC ha s be e n f oun d i n on ly t hef a r t h e s t d r a i n a g e s - - R i o C a fi et e, R i o S an J u a n , a n d R i o P is c o. T h e o n l yexcept ions a re found in s ing le access ions (LA94, 1295) each in the

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Mating Systems in Lycopersicon hirsutum 291:ble 2 (continued)

~x-1 P rx-2 Prx-3 Prx-3b Prx- 4 Prx -7a Prx-7%

polymorphicloci

+ + n B + ++ + r5 A + ++ + n A + ++ + n F + ++ + n F + ++ + n F + ++ + n F + ++ + r5 E + ++ + r5 E + ++ + r5 B + +

14700000007

R im a c a n d C h i ll 6n va l l e ys , t he n e x t m a in d r a ina ge s no r th o f R ioCaf ie te .

O th e r de pa r tu r e s f r om th i s a s s oc i a ti on o f ge ne t i c va r i a b i l i t y a ndc om pa t ib i l i t y r e a c t i on a r e s e en i n t h r e e a c c e s s ions - - L A 1295, 1559, a nd1 7 6 1 - - w h i c h a r e S I y e t d i s p l a y e d n i l p o l y m o r p h y . W h e t h e r t h e s er e p r e s e n t t r u ly e xc e p t i ona l s i t ua t i ons o r sa m pl ing e r r o r s is no t c e r t a in ,b u t i t is n o t e w o r t h y t h a t , a s o b s e rv e d a b o v e , S C h a s b e e n d e t e c t e d inthe s e r e g ions , w h ic h a r e o the r w i s e c om ple t e ly S I . Fu r the r m or e , t hege ne r a l l e vel o f va r i a b i l i t y i n t he s e tw o v a l l e ys ( R io C h il l6n a nd R iol%imac) is lower tha n th a t o f o th e r p a r t s o f' the SI t e r r i to ry .

P e r t i n e n t t o t h e s e c o n s i d e r a t i o n s i s t h e f a c t t h a t , c o n t r a r y t o o u rre su l t s , b o t h SC and SI we re de te c te d by MARTIN (1963) wi th in the samepopula t ions of LA 387 (Santa Apolonia ) an d of PI 127 ,827 co l lec ted a t th eI nc a B a t hs ne a r C a j a m a r c a 19 ye a r s p r i o r t o ou r c o l l ec t ion (L A 386) a tt he s a m e s i te . T he e x i s t e nc e o f SC p l a n t s i n the s e po pu l a t i on s m igh ta c c o u n t f o r t h e f a c t t h a t w e m e a s u r e d c o n s i d e r a b l y lo w e r le v el s o fp o l y m o r p h y i n t h e m t h a n i n o t h e r ac c es si o ns f r o m N W P e ri l. I t s h o u l da ls o be no t e d t h a t , i n c on t r a s t t o a l l o f t he m or e s ou the r ly d i s t r i bu t i ono f L. h i r~ 'u tum, t he s e s i t e s in t he v i c in i t y o f C a j a m a r c a l ie e as t o f t hec o n t i n e n t a l d i v id e a n d m i g h t t h e r e f o r e r e p r e se n t a n o t h e r m a r g i n al ,p ione e r ing e nc l a ve.

W ha te v e r t he n a tu r e o f t he s e s e em ing e xc e p t i ons , t he d i f f e r e nc e i nge ne t i c va r i a b i l i t y be tw e e n SC a nd S I a c c e s s ions i s im pr e s s ive : t hem e a n po lym or ph y f o r a ll SC pop u l a t i on s is 1 .5~o w h i l s t t h a t f o r S I i s21 .4~o - -a four te en- fo ld d i f fe rence . Th e s ta t i s t i ca l s ign i f icance of th i sd i f f e re nc e is be y on d qu e s t i on be c a us e t he tw o d i s t r i bu t i ons s c a r c elyove r l a p . T he d i f f e re nc e l ie s i n t he e xpe c t e d d i r e c t i on , b u t s e em s t o

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292 C.M. RICK et al . :e x c e e d t h e e x p e c t e d m a g n i t u d e . A l t h o u g h t h e f l o ra l d is p l a y o f S Ca c c e s si o n s is g e n e r a l l y le ss t h a n t h a t o f t h e S I g r o u p , f lo w e r s o f t h ef o r m e r n e v e r t h e le s s a t t r a c t p o l l i n a t i n g b e e s i n c o n s id e r a b le n u m b e r sa c c o r d i n g t o o u r o b s e r v a t i o n s . T h u s , w e h a v e w i t n e s s e d v i s i t a t i o n s o fb e e sp p . t h a t w e r e u n m i s t a k a b l y g a t h e r i n g p o l le n f r o m f lo w e r s o fL A 12 53 a n d 1264. S C t h e r e f o r e c o u l d h a r d l y s e e m e n t i r e l y a c c o u n t a b l e

A n o d o l - I- A B C D E F GF r o n t L o c u sI

3

4i l l I I I I

5Or ig in

Fig . 1 . Ph eno type s o f a ll eles o f P r x - 4 in L . h i r s u t u m . Mean d i s tance f rom or ig into an odal f ron t is 10 .8-11 .0cm. Fu l l a r r ay of anodal p erox idase bands i si l lus t ra ted on ly fo r P r x - 4 + at l e f t

f o r t h e n e a r - z e r o v a r i a b i l i t y o f t h e S C a c c e s s io n s . A s im i l a r r e l a t i o n s h i pb e t w e e n c o m p a t i b i l i ty t y p e s a n d e x t e n t o f v a r i a b i l i ty h a s b e e n o b -s e r v e d b y L EV IN ( 19 7 8) b e t w e e n P h l o x s p p . an d b y SOLB R m & R OLLINS( 1 9 7 7 ) b e t w e e n L e a v e n w o r t h i a s p p . ; h o w e v e r , J A ~ (1 97 6) a n d o t h e r s ,p o i n t i n g o u t v a r i o u s e x c e p t i o n s , c a u t i o n a g a i n s t e x p e c t i n g c o r r e l a ti o n sb e t w e e n r a t e s o f o u t c r o s s i n g a n d d e g r e e o f g e n e t i c v a r i a b i l i t y t o b eu n i v e r s a l . I n s u c h s tu d i e s i t h a s s e l d o m b e e n p o s s ib l e to m a k e e x t e n s i v ec o m p a r i s o n s w i t h i n s p e ci es a s p e r m i t t e d b y L . h i r s u t u m . T h e h a z a r d s o fd r a w i n g c o n c l u si o n s i n c o m p a r i s o n s b e t w e e n s p e c i e s w i t h t h e i r w i d e l yd i f f e r e n t a d a p t a t i o n s , d e g r e e s o f p o l y p l o i d y , r a t e s o f r e p r o d u c t i o n , a n do t h e r f a c t o r s a r e o b v i o u s .

T h e d a t a s u g g e s t t h a t i n t h e m i g r a t i o n o f L . h i r s u t u m f r o m t h ec e n t r a l r e g i o n , a d v a n t a g e o f f i x in g o n e o r a f e w h i g h l y s u c c e ss fu lg e n o t y p e s o r t h e f a i l u r e t o o b t a i n t h e n e c e s s a r y p o p u l a t i o n s i ze o r

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Mating Systems in Lycopersicon hirsutwm 293

Figs. 2 4. Geographic relationships for genetic variability, self-incompatibility,and alleles present at several loci. Circles represent, populations s amp le d. -Fig. 2. Proportion of tested loci that were polymorphie (percent polymorphy)represented by the black portion of each eirele.--Fig. 3. Compatibilityrelations. C = self-compatible; I = self-ineompatible.--Fig. 4. Total scores offive loci differentiating northern and southern elements of L. hirsutum.Northern alleles represented by white; southern alleles, by black, See text forfurther informationpollen vectors m ight ha ve resulted in subs tit uti on of SC. Considerationof the problems in the evolution of compatibility types by LEw~s &CROWE (1958), DENETTANCO[TRT 1977) and others leads to the conclusionth at the evolution of SC from si is far simpler than the reverse. For thisand other reasons SI is generally considered ancestral to SC.

19 P1. Syst . Evol ., Vol. 132, No. 4

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294 C.M. RICK et al. :H y p o t h e s e s b a s e d o n a c o m m o n o r i g in f o r t h e t w o g r o u p s o f S Ca c c e s s i ons a r e ne ga t e d by t he ge ne t i c d i f f e r e nc e s obs e r ve d be t w e e n t het w o , a s de l i ne a t e d be l ow .

Regional Trends; Morphological CharactersT he n o r t h e r n a nd s ou t he r n S C g r ou ps d i f f e r i n t he a ll el es p r e s e n t a t

f i ve o f t he f ou r t e e n i nve s t i ga t e d e n z ym e l oc i. T hus a t Aps-2 t he + a nda2 a l l e l e s a re f i xed re spec t ive ly ; fo r Got-I, + a n d a2 ; fo r Got-2, a20 a n d

Fig. 5. Rep rese ntativ e flowers of three accessions of L. hirsutum. Left : LA407(Guay aquil, self-compatible). Center: LA 1721 (Ticrapo Viejo, self-compatible).Right: LA1772 (Canta, self-incompatible). Note differences in corolla size

a8; fo r Prx-4, t he A a l le l e vs t he o the rs ; and for Prx-3b, t h e r4 b a n d w a sp r e s e n t i n s om e s ou t he r n a c c e ss i ons bu t w a s ne ve r de t e c t e d i n t heno r t he r n g r oup . T h i s s ubs t i t u t i on o f a ll el es a t 36~ o f t he loci c on -s t i t u te s a r e m a r k a b l e d e g r e e o f g e n e t ic d i f f e r e n t i at i o n a n d a f o r m i d a b l ea r g u m e n t a g a i n s t a c lo se p h y l o g e n e t i c r e l a t io n s h i p b e t w e e n t h e t w og r o u p s . F u r t h e r , t h e e l e e t r o p h o r e t i c d a t a a r e c o n s i s t e n t w i t h o b s e r -va t i o ns on d i ve r g e nc e i n l e a f s iz e, f low e r s iz e a nd c o lo r , a nd o t he rm o r p h o l o g i c a l ch a r a c t er s . T h e d i f f e r e n t i a ti o n o f n o r t h e r n a n d s o u t h e r nb i o t y pe s i s s um m a r i z e d i n F i g . 4 f o r the s e e nz y m e l oci om i t t i ng Prx-3b.All c ha r a c t e r s a r e g i ve n e qua l w e i gh t , t he no r t he r n a l l e l e s s i gn i f i e d byw h i t e , t he s ou t he r n a l l e l e s by b l a c k .

O t he r i n t e r e s t i ng f e a t u r e s a r e t he obs e r ve d m or pho l og i c a l d i f -f e r e nc e s t ha t t e nd t o be a s s oc i a t e d w i t h S C . C or o l l a l i m b d i a m e t e r i sge ne r a l l y s m a l l e r t ha n t h a t o f t he S I popu l a t i ons , t he d i f f er e nc e be i ngg r e a t e r i n t he n o r t h e r n S C g r ou p ( F ig . 5 ). T he s e c h a nge s i n t he S C r a c e se v i d e n t l y e vo l v e d a s a r e s u lt o f t he l a c k o f s e l ec t ion p r e s s u r e f o ra t t r a c t i v i t y t o po l l i na t i ng be es , s o e s s e n t ia l to t he r e p r od uc t i on o f S I

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Mating Systems in Lycopersicon hirsutum 295b io type s . A s t r a nge b u t c ons i s t e n t d i f f e r enc e s e en i n bo th no r the r n a nds o u t h e r n S C g r o u p s i s t h e t e n d e n c y t o w a r d t h i n n e r s t e m s , m o r ed i m i n u t i v e p l a n t p a r t s , a n d g r e a t e r b a s a l b r a n c h i n g t h a n i n t h e S Ia c c es s ions as a w ho le . P r e s um a b ly t he f i x a t i on o f t he s e c ha r a c t e r s a l sor e f le c t s t he a c t i on o f na t u r a l s e l ec t ion s i nc e t he y a r e f i xe d i n bo th e ndso f t he d i s t r i bu t i on , bu t t h e ba si s f o r suc h s e l e c t i on is no t c l ea r a t t h i st im e .

A s p r e v iou s ly m e n t ion e d , a dd i t i on a l l oc i o f Est a n d Pgm w e r e t e s t e df o r c e r t a in bu t no t a l l a c c e s s ions . T he s e a dd i t i ona l da t a c a n besummar ized br ie f ly a s fo l lows . S ix SC access ions were t e s ted for twoPgm a nd t e n f o r the f i ve a dd i t i ona l Est loc i ; a ll access ions pro ve d to behom om or p h i c f o r t he s e loc i. A m o ngs t t he S I a c ce s sions, 15 w e r e t e s t e dfo r Pgm a nd 10 f o r t he a dd i t i ona l Est ge ne s ; f i ve w e r e po ly m o r ph i c f o ra t l ea s t one Pgm a n d e i g h t w e r e p o l y m o r p h i c a t o n e o r m o r e Est loci.T he s e r e s u l t s a r e t he r e f o r e c onc o r da n t w i th t he c om ple t e ly t e s t e d l oc it o t he e x t e n t t ha t no va r i a b i l i t y w a s f ound i n a ny SC a c c e s s ion i nc on t r a s t w i th t he e x t e ns ive f l uc tua t i ons s e e n i n t he S I m a te r i a l . I t i sa ls o o f i n t e r e s t t o no t e t h a t va r i a t i on a t t he a dd i t i on a l l oci w a se nc o un t e r e d f o r a S I a cc e s sion ( L A 176 i ) t ha t p r o ve d ho m o typ i c in t het e s t s f o r o the r e l e c t r ophor e t i c l oc i . T h i s i n f o r m a t ion s ugge s t s t ha t t heun i f o r m i ty r e g i s t e r e d f o r t he 14 s t a nda r d ge ne s m igh t ha ve be e n a na r t i f a c t r e s u l t i ng f r om s m a l l s a m ple s i z e a nd /o r i nb r e e d ing du r inga c c e s s ion s e e d i nc r e a s e s . I n s um m a r y , t he s e a dd i t i ona l da t a l e ndf u r t h e r s u p p o r t t o t h e p r e v i o u s l y o b s e r v e d m a r k e d d i ff e re n c es i nge ne t i c va r i a b i l i t y be tw e e n t he SC a nd S I g r oups .

A s t o g r os s m or pho logy , w e ha ve be e n im pr e s s e d by t he ge ne r a l l ylow l eve l o f va r i a t i o n w i th in popu l a t i on s , w h e the r i n the w i ld o r t e s tp r oge n i e s i n c u l tu r e . I n c on t r a s t , t he a c c e ss ions , pa r t i c u l a r l y t hos e f r omdi f f e r e n t d r a ina ges , o f t e n d i f f e r f r om e a c h o t he r i n s uc h f e a tu r e s a s s iz eo f v e g e t a t i v e p a r t s , h a i ri n es s, a n t h o c y a n i n p i g m e n t a t i o n , a n d v a r i o u sf e a tu r e s o f t he c a lyx , f r u i t s iz e a nd pa t t e r n o f c o lo r a t i on . Ma r ke d g r ossm or pho log i c a l va r i a b i l i t y ha s be e n obs e r ve d within access ions f rom th eH u a n c a b a m b a r e g io n ( th e n o r t h e r n m o s t P e r u v i a n c o l le ct io n s) , w h e r ee l e c t r o p h o r e t ie p o l y m o r p h y a ls o r e ac h e s a m a x i m u m . T h i s r eg i o n isa ls o un ique f o r he t e r om or p hy a t t he ha i r c o n t r o l l oc us (h) ( T a b l e 1).

I n s o f a r a s c om pa r i s ons a r e pe r m i t t e d , t he p i c tu r e o f m or pho log i c a lv a r i a b i l i t y a g re e s w i t h t h a t f o r z y m o t y p e s . T h e t w o s et s o f d a t a a r ec on c or d a n t i n t ha t : 1) r a c es f r om d i f f e r e n t va l le ys ar e c ons ide r a b lyd i f f e r e n t i a t e d f r o m e a c h o t h e r ; 2 ) p o p u l a t i o n s t h a t a r e m o n o m o r p h i c inz y m o t y p e t e n d t o b e u n i f o r m in g ro s s m o r p h o l o g y ; a n d 3) p o p u l a t i o n sw i t h g r e a t e s t z y m o t y p i c p o l y m o r p h y t e n d t o b e v a r ia b l e in g r o ssm o r p h o l o g y . P r e v i o u s i n s t a n c es o f s u c h a g r e e m e n t w e r e fo u n d i n L .cheesmanii (RICK& FOBES 197 5a), L. pimpinellifolium (RICK& al. 1977),

19"

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296 C.M. RICK et al. :and the sibling species L. chmielewskii and L. parviflorum (RICK & al.1976). These accrued examples lend abundant support to the use ofisozymes as indices of genetic varia tion in the tomato species.

General ConsiderationsThe preceding observations support the following hypothesis for

evolution of L. hirsutum. Assuming t ha t SC forms evolved from SI, thecentral populations would be ancestral to those in the northern andsouthern margins of the distribut ion. Within the central SI group, thenorthern populations (Dept. Piura, Cajamarca, La Libertad) exhibitthe greatest variation. We therefore suggest that they also representthe oldest living biotypes of L. hirsutum, from which the others werederived. As the species migrated northward and southward through itselongated distribution, SI was replaced by SC possibly as a result ofselection for greater uniformity and for fewer and more weedy geno-types and/or of founder events in which SC might have been essentialfor the survival in diminished populations, in conformity with BAKER'S(1955) law.It is noteworthy that the patterns of variability and suggestedevolution of mating systems in relation to geographic distribution forL. hirsutum conform with remarkable exactness with those proposedfor L. pimpinellifolium (RICK & M. 1977). Although the la tter species isentire ly SC, outcrossing in the marginal populations at zero or near zerolevels grades to a maximum in the central region. These extraordinaryparallels are even matched by similar changes in flower size. The twosystems must have evolved independently since the two species are notclosely related. It is also significant tha t the evidence points to the samegeneral region as the center of origin of both species. This area is alsounique floristically for the presence of an unusually large number ofendemic species, also because it is transitional between the moisttropics of the Ecuador ean habitats to the north and the temperat edeserts to the south.

SummaryVariation was measured for allozymic banding at fourteen genetic

loci in acid phosphatase, esterase, glutamate oxaloacetate trans-aminase, peroxidase, and phosphoglucomutase and for morphologicalcharacters in progenies of wild populations of Lycopersicon hirsutum.Flower size was measured and reactions to self-pollination tested inthese progenies grown at Davis, California. In the elongate distributionof this species oriented NNW-SSW, Mlozymic polymorphy varied fromzero in the northernmost and southernmost populations to values as

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Mating Sy stems in Lycope~'sicon hirsutum 297h i gh a s 72~o i n no r t hw e s t e r n P e r il . P o pu l a t i o ns at t h e t w o e x t r e m i t i e sd i f fe red in a l l e le s f ixed a t f i ve (34~o) of t he t o t a l t e s t e d genes . S imi l a rva r i a t i o n w a s ob s e r ve d i n c o r o l la s iz e a nd c o lo r , l e a f d i m e ns i ons ,e p i d e r m a l h a i r s, a n d p l a n t h a b i t . S e l f - c o m p a t i b i l i t y w a s d e t e c t e d i nt h e s e m a r g i n a l p o p u l a t i o n s a n d t w o m o r e c e n t r a l l y l o c a t e d a c ce s si o ns ,s e l f - i nc om pa t i b i l i t y i n t he r e m a i nd e r o f t he r a nge . T h e de g r e e o fv a r i a t i o n in a ll o b s e r v e d c h a r a c t e r s w a s v a s t l y g r e a t e r in t h e l a t t e r t h a ni n t he f o r m e r g r oup , t he d i f f e r e nc e doub t l e s s l y ow i ng i n pa r t t o t hedi f fe rence in breeding sys tems. Se l f -compat ibi l i ty i s a l so assoc ia ted wi ths m a l l e r c o r o ll a d i m e ns i on s t h a n s e l f - i nc om pa t i b i l i t y , t he d i f fe r e nc eb e i n g g r e a t e r i n t h e N o r t h . T h e s e p a t t e r n s o f v a r i a b i l i t y a n d f i x a t i o n o fa l l e l e s c o i nc i de ve r y c l o s e l y t o t hos e p r e v i ous l y d i s c ove r e d i n L .pimpinel l i fol ium. T h e h y p o t h e s i s o f e v o l u t i o n i n L. hirsutum, as alsop r o p o s e d f o r t h e o t h e r s p e c i e s , t h a t i s m o s t c o m p a t i b l e w i t h t h e d a t aa s s u m e s t h a t t h e m o r e u n i f o r m s e l f - c o m p a t ib l e r a c es a t t h e e x t r e m i t i e so f t he d i s t r i bu t i on w e r e de r i ve d p r og r e s s i ve l y f r om t he s e l f- i nc om -pa t i b l e b i o t yp e s i n t he c e n t r a l r e g i on o f h i gh va r i a b i l i t y .

Research supp orted in par t b y NS F Gra nt D EB 77-02248. We grateful lyacknowledge the indispensable assistance of the following colleagues andassistants. Various accessions of L. hirsutum were collected and contributed byIng . DAVID BAUMAN~, Dr. RAYMONDCLARK, I n t . TOM.4S GUERRERO, Dr. MmUELHOLLE, ng . DAXlaLNAKAMA,Dr. CARLOSOC~OA,Ing. EDUARDOVALLEJOS,and Dr.HAROLD WINTERS.Field and greenhouse operations were directed by PAULBOSLAND, as si st ed by CRAm GIANINNI, DORA HUNT, HERCULANOMEDINA, andRANDY SCHUSTER. D01%AHUNT assisted in editing the m an us cri pt and MOIRATANAKA did the ca rto gr ap hy .

ReferencesBAKER, H. G ., 1955: Self-com patibili ty and establis hm ent after long-d istancedispersal . -- Evolut ion 9, 347--348.JAIX, S.K ., 1976 : Po pula tion struc ture and the effects of breeding sy stem . InFRANKEL, O. H., I:IAWKES, . G. (Eds.) : Plan t Genet ic Resources: To day andTomorrow. - - London: Cambridge Univ. Press .LEVIX, D.A ., 1978: Genetic va riatio n m ann ual phlo x: self-compa tible versusself-incompatible species. - - Ev olu tion 32, 245--263.LEWIS, D., CROWE, L .K ., 1958: Un ilat era l interspecific inc om pa tib ility in flow er-ing plants . -- Heredi ty 12, 233--285.MARTIN, F. W ., 1963 : Distrib ution and interrelationsh ips of inco mp atibili tybarriers in the Lycopersicon hirsutum Hum b. & Bonpl. complex. - - Evolu-t ion 17,519--528.McGumE, D.C ., RICK, C.M., 195 4: Self-inco mpa tibili ty in species of Lyco-persicon sect. Eriopersicon and hybrids with L. esculentum. - - Hi]gardia 23,101--124.MULLER, C. H ., 194 0: A r evi sion of the gen us Lycopersicon. - - U.S. Dept. Agric.Misc. PubL 382.

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298 C.M. RICK et a l . : Ma ting Sy ste ms in Lycopersicon hirsutumNETTANCOURT,D. DE, 1977: Se lf - in com pati bi l i ty . - - Ber l in: Spr in ger .RICK, C. M.I FOBES, J . F . , 1975a : Al lozym es of Ga lpagos tom atoe s : po lym or -ph i sm, ge og r a ph ic d i s t r i bu t ion , a nd a f fin i ti e s . - - E vo lu t ion 23 , 443 -- 457 .- - - - 1975b : A l loz yme va r i a t i on in t he c u l t i va t e d tom a to a nd c lo sely r e l a t e dspecies . - - Bull . Torre y Bot . Club 102, 376--384.- - - - 1976: P e r ox ida s e c omple x a nd c onc o mi ta n t a noda l a nd c a thoda l va r i a -t i on in r e d - f r u i t e d toma to spe c i e s . - - P r oc e e d ings , N a t iona l A c a de my o fScience 73, 900--904.- - - - HOLLE, M., 1977: Genetic var i a t io n in Lycopers icon p impinel l i fo l ium:evidence of evo lu t i ona ry change in ma t ing s ys tems . - - P1. Sys t . Evol . 127,139- -170 .- - HOLLE, M., THORP, R .W ., 1978 : Rat es of cro ss-po ll inat i on in Lycopersiconp impinel l i fo l ium: imp a c t o f ge ne t ic va r i a t i on in fl o r al c ha ra c t e r s. - - P 1 .Syst . Evol . 129, 31--44.- -KE SIC KI, E. , FOBES, J .F . , HOLLE, M., 1976: Gene tic and bio sys tem atics tud ies on two new s ib l ing species o f Lycopersicon f rom in te randean , Pe r i l .- - Theor . Appl . Gene t ic s 47 , 55~-68 .SINGS, R. , 1976: S ubs t ra te - spec i f ic enzym e va r i a t io n in na tu ra l pop ula t io ns ofDrosophila pseudoobscura. -- Gene t ic s 82 , 507- -526 .SOLBRIG, O., ROLHNS, R .C ., 1977 : Th e ev ol uti on of au to ga m y in sp ecies of th em u s t a r d g e n u s Leavenworthia . - - E v o l u t i o n 3 1 , 2 6 5 - - 2 8 1 .STONER, A .K . , 1970: Bree ding for insect re sis tan ce in vegetable s . - - Ho rt-Science 5, 76--79.

Ad dres ses of the au tho rs: Dr . CHARLESM. RICK an d Mr . STEVEND. TANKSLEY,D e pa r t me n t o f V e ge ta b le Cr ops , U n ive r s i t y o f Cal i fo r n ia , D a v i s , Ca l i f or n i a95616, U .S .A . - -D r . JoN F . FOBES, De pa r tm en t o f Hor t icu l tu re , Michigan S ta teUnive rs i ty , Eas t Lans ing , Michigan 48824 , U.S .A.