Transferrin variation and genetic structure of reindeer populations in Scandinavia

Transferrin variation a n d genetic structure of reindeer populations i n Scandinavia T r a n s f e r r i n - v a r i a s j o n o g genetisk s t r u k...
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Transferrin variation a n d genetic structure of reindeer populations i n Scandinavia T r a n s f e r r i n - v a r i a s j o n o g genetisk s t r u k t u r hos rein i Skandinavia K n u t H . Røed , T. Mossing , M . N i e m i n e n & A . R y d b e r g 1

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Department of Zoology, Agricultural University of N o r w a y , Box 46, 1432 Ås-NLH, N o r w a y . Present adress: Department of Animal Husbandry and Genetics, The Norwegian College of Veterinary Medicine, Postbox 8146, D e p . 0033 Oslo 1, N o r w a y Department of Ecological Zoology, University of Umeå, S-90187 Umeå, Sweden Finnish Game and Fisheries Research Institute, Koskikatu 33A, SF-96100 Rovaniemi, Finland Department of Reindeer Research, Box 5097, S-90005 Umeå, Sweden

Abstract: Polyacrylamide gel electrophoresis was used to analyse transferrin variation in herds of semi-domestic reindeer from Scandinavia. The results are compared with previously reported values for other populations of both semi-domestic and wild reindeer using the same techniques as in the present study. In all populations the number of alleles was high, ranging from seven to eleven, and the heterozygosity was correspondingly high, with a mean of 0.749. This high genetic variation in all populations suggests that inbreeding is not widespread among Scandinavian reindeer. The pattern of allele frequency distribution indicates a high degree of genetic heterogeneity in the transferrin locus, both between the different semi-domestic herds and between the different wild populations. The mean value of genetic distance was 0.069 between semi-domestic herds and 0.091 between wild populations. Between semi-domestic and wild populations the genetic distance was particularly high, with a mean of 0.188. This high value was mainly due to a different pattern in the distribution of the two most common transferrin alleles: Tf was most common among semi-domestic herds, while Tf was most common among wild populations. These differences in transferrin allele distribution are discussed in relation to possible different origins of semi-domestic and wild reindeer in Scandinavia, or alternatively, to different selection forces acting on transferrin genotypes in semi-domestic and wild populations. u

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R ø e d , K . H . , M o s s i n g , T . , N i e m i n e n , M . & R y d b e r g , A . 1987. T r a n s f e r r i n - v a r i a s j o n o g genetisk s t r u k t u r hos rein i S k a n d i n a v i a . Sammendrag: Transferrin-variasjon i tamreinflokker ble analysert ved hjelp av polyacrylamid gel elektroforese. Resultatene er sammenlignet med verdier som tidligere er beskrevet for både tamrein og villrein hvor det ble benyttet samme metode som i denne undersøkelsen. I alle populasjonene ble det registrert et høyt antall alleler (7-11) og heterozygositeten var tilsvarende høy med en middelverdi på 0.749. Denne høye graden av genetisk variasjon i alle undersøkte populasjoner indikerer at det ikke foregår mye innavl blant rein i Skandinavia. Utbredelsen av de enkelte allelene viste høy grad av genetisk oppdeling i transferrin-locuset mellom flokker av både tamrein og villrein. Middelverdien for genetisk avstand var 0.069 mellom tamreinflokker og 0.091 mellom villreinflokker. Særlig stor genetisk avstand (middelverdi 0.188) ble funnet mellom tamrein og villrein. Denne store forskjellen skyldes i stor grad forskjellig mønster i utbredelsen av de to vanligste allelene: Tf' var mest vanlig blant tamrein og Tf ' var mest vanlig blant villrein. Denne forskjellen er diskutert i relasjon til forskjellig opprinnelse av tamrein og villrein og alternativt, i relasjon til forskjellig seleksjonskrefter som virker på transferrin genotyper i tamrein og villrein. 1

R a i t g i f e r 7 (1): 12 - 21 12

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Introduction Reindeer i n Scandinavia are separated into n u m e r o u s different p o p u l a t i o n s and exist b o t h as semi-domestic and w i l d animals. T h e amount of differentiation and the e v o l u t i o n of the different p o p u l a t i o n s are, h o w e v e r , h i g h l y u n k n o w n and o p e n to speculation. Studies of the genetic structure of reindeer p o p u l a t i o n s may p r o v i d e some insight i n t o the e v o l u t i o n a r y events and processes that have shaped the present structure. M o s t w o r k o n the genetic structure of reindeer p o p u l a t i o n s has been based o n m o r p h o l o g i c a l characteristics. Such studies suffer f r o m the d i f f i c u l t y of d i s t i n g u i s h i n g between genetic and e n v i r o n m e n t a l c o m p o n e n t s of v a r i a t i o n . T h e i n t r o d u c t i o n of electrophoretic techniques a l l o w e d studies of single factors w i t h k n o w n inheritance. G a h n e and R e n d e l (1961) used this technique and were the first to study genetic variation i n the locus c o d i n g for serum transferrin i n reindeer. T h e v a r i a t i o n i n this locus has later been used i n several m o r e studies of p o p u l a t i o n genetics i n reindeer and c a r i b o u (Brænd 1964; S h u b i n 1969; 1977; S h u b i n and Ionova 1984; S h u b i n and M a t y u k o v 1982; T u r u b a n o v and S h u b i n 1971; Z h u r k e v i c h and F o m i c h e v a 1976; Storset et al. 1978; S o l d a l and Staaland 1980; R ø e d 1985a,' 1985b, 1986; R ø e d and W h i t t e n 1986; R ø e d et al. 1985, 1986). T h e m a i n pattern of v a r i a b i l i t y reported i n these studies indicates considerable genetic heterogeneity i n the transferrin locus a m o n g p o p u l a t i o n s of reindeer. A p a r t i c u l a r l y h i g h a m o u n t of differentiation was detected between p o p u l a t i ons of semi-domestic and w i l d reindeer i n southern N o r w a y (Brænd 1964; R ø e d 1985a). T h e purpose of the present study_was to test whether this large differentiation remains evident w h e n several m o r e p o p u l a t i o n s f r o m other parts of Scandinavia are i n c l u d e d i n the analyses. T h e transferrin allele frequencies of nine herds of semi-domestic reindeer f r o m N o r w a y , Sweden and F i n l a n d are presented i n this study and c o m p a r e d w i t h allele frequencies of b o t h semi-domestic and w i l d reindeer i n N o r w a y reported i n previous studies using the same techniques and allelic designation (Røed 1985a, 1986, R ø e d et al. 1985). Material and

methods

B l o o d samples were obtained f r o m 842 reindeer b e l o n g i n g to the f o l l o w i n g 9 semiR a n g i f e r , 7 (1), 1987

domestic reindeer herds o r areas i n Scandinavia (Fig. 1): F i n l a n d : K a a m a n e n (1), i n the n o r t h e r n part of the c o u n t r y . N o r w a y : V u o r j e n j a r g (2), A r n ø y (3) and Laggonjargga (4) f r o m F i n n m a r k c o u n t y , K a n s t a d f j o r d (5) f r o m T r o m s c o u n t y and Essan (9) f r o m Sør-Trøndelag county. S w e d e n : R a n / U m b y n (6) in Våsterbotten c o u n t y , A r v i d s j a u r (7) i n N o r r b o t t e n c o u n t y and H a n d o l s d a l e n (8) i n J a m t l a n d c o u n t y . L o c a t i o n of those p o p u l a t i o n s f r o m N o r w a y i n c l u d e d for comparisons i n the present study are also given i n F i g . 1: A b o r a s s a (10), Joakkenjargga (11), R i a s t / H y l l i n g (12), T r o l l h e i m e n (13), J o t u n h e i men (14), F i l l e f j e l l (15), H o l (16), H a r d a n g e r v i d d a (17), H a l l i n g s k a r v e t (18), Snøhetta (19), Knudshø (20) and F o r e l h o g n a (21). A l l herds belong to the subspecies Eurasian tundra reindeer, R. t. tarandus. T h e herd sampled i n A r v i d s j a u r area (7) was of the forest reindeer type w h i l e the others were of the m o u n t a i n reindeer type. P o p u l a t i o n s 17-21 are w i l d reindeer, a m o n g w h i c h the F o r e l h o g n a (21) p o p u l a t i o n is believed to have its o r i g i n m a i n l y f r o m semi-domestic reindeer f r o m Sweden (Skogland 1984). T h e semi-domestic R i a s t / H y l l i n g herd (12) is identical to the R ø r o s herd i n a previous report (Røed 1985a). B l o o d samples were taken i n t o h e p a r i n i z e d test tubes and centrifuged, after w h i c h the plasma fraction was r e m o v e d and stored at — 2 0 ° C u n t i l the electrophoretic analysis was p e r f o r m e d . Plasma samples were subjected to vertical slab p o l y a c r y l a m i d e gel electrophoresis as p r e v i o u s l y described b y R ø e d (1985a). T h e transferrins were stained w i t h C o o m a s s i e B r i l l i a n t B l u e R 2 5 0 ( D i e z e l et al. 1972). Results N i n e separate alleles, each consisting of a d o u b l e b a n d , c o u l d be resolved i n the present material after r e - r u n n i n g similar alleles side by side to c o n f i r m their electrophoretic i d e n t i t y . E a c h alleles was scored as a d o u b l e b a n d as given in F i g . 2. T h e allele frequencies i n the transferrin locus f o r each p o p u l a t i o n are given i n T a b l e 1, together w i t h frequencies of those p o p u l a t i o n s i n c l u d e d f o r c o m p a r i s o n s . T a b l e 2 shows the amount of genetic v a r i a t i o n i n the transferrin locus f o r each of these p o p u l a t i o n s . T h e h e t e r o z y g o s i t y i n T a b l e 2 is calculated as expected frequencies of heterozygotes f r o m observed allele frequencies ( L e w o n t i n and H u b b y 1966). In all p o p u l a t i o n s the n u m b e r of 13

Fig. 1. Map showing locations of the sampled populations of semi-domestic (1-16) and wild (17-21) reindeer. Fig. 1. Kart som viser lokalisering av populasjoner av tamrein (1-16) og villrein (17-21) som er analysert. 14

Rangåfer, 7 (1), 1987

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