GENETIC VARIATION IN BLOOD PROTEINS WITHIN AND DIFFERENTIATION BETWEEN 19 SHEEP BREEDS FROM SOUTHERN AFRICA
By .
JANICE SARGENT
Dissertation
presented in partial fulfillment .of
the requirements for the degree
MASTER of SCIENCE
ZOOLOGY
in the
FACULTY 'OF-NATURAL SCIENCES
of the
Rand . Afrikaans University
Supervisor: Prof F.H. van der Bank
Co-suPervisor: Antoinette Kotze
October 2000 . PAGE LIST OF CONTENTS
ABSTRACT ii
OPSOMMING iii
PREFACE vi
ACKNOWLEDGMENTS
CHAPTER 1 1 - 1 1. INTRODUCTION 1 - 2 2. COMPARITIVE CHARACTERISTICS OF 19 SHEEP 1 - 5 BREEDS FROM SOUTHERN AFRICA 3. OBJECTIVES OF STUDY 1 - 42
CHAPTER 2 2 - 1 GENETIC VARIATION IN BLOOD PROTEIENS 2 - 1 WITHIN AND BETWEEN 19 SHEEP BREEDS FROM SOUTHERN AFRICA MATERIALS AND METHODS 2 - 2 RESULTS 2-12 DISCUSSION 2-22
CHAPTER 3 SUMMARY 3 - 1
CHAPTER 4 4 - 1 REFERENCES 4 - 2
APPENDIX I GENEPOP INPUT FILE FOR 19 SHEEP BREEDS GENEPOP INPUT FILE FOR SIX SHEEP BREEDS
APPENDIX II ELECTROPHORETIC RESULTS OF SELECTED ENZYME SYSTEMS GELS 1. PEROXIDASE GLUCOSE-6-PHOSPHATE ISOMERASE HAEMOGLOBIN LACTOSE DEHYDROGENASE Abstract
The amount of allozyme variation within, and the extent of genetic differentiation between, 19 sheep breeds from southern Africa were determined by six enzyme coding loci. Another eight enzyme coding loci were analyzed for five breeds. Between 55 and 66.67% of the protein coding loci were polymorphic (95% criterion) in all the breeds, except for the Namaqua sheep that were less polymorphic (33.33%). Values of 1.67 to 2.5 were obtained for the mean number of alleles per locus and average heterozygosities per locus was between 16.6 to 35.9%. The allelic constitution particularly at the transferrin (TF) locus varied appreciably for the different breeds. For example, the TF*H allele was exclusively noted in the Dormer sheep and the TF*G allele was found in the Afiino, Van Rooy, Border Leicester, Blackhead Persian and Skilder-Persian breeds. The only polymorphic breeds at the albumin locus were the South African Mutton Merino and Van Rooy breeds. The allelic constitution at the other polymorphic loci was similar for the breeds, but the allele frequencies of the South African Merino differs from Merino breeds in other countries at the TF locus. Unbiased genetic distance values were the smallest between the Dorper and Dormer breeds and the largest between the Romenof and Blackhead Persian breeds, and the mean genetic distance between the 19 breeds was 0.067. The mean amount of differentiation among the breeds relative to ' the limiting amount under complete fixation (F ST) was calculated at 0.123, which is an indication of small genetic differentiation between the breeds studied. However, this , statistic is not reflected by the allele distribution that was not identical for 25 breed pairs (15%) of the total (171) at all the genetic blood systems studied. None of the breed pairs showed identical allele distributions at all the loci studied for at least one locus differed at each breed pair compared. Random amplified polimorphic DNA's gave no consistent or repeatable results. The results of the allozyme study presents the first study of the current genetic characterization of the different southern African sheep breeds.
ii OpSomming Die hoeveelheid allosiemvariasie binne en' die mate van genetiese differensiasie tussen 19 skaaprasse van suider Afrika was bepaal deur Van ses algemeen genetiese bloedsisteme gebruik to maak:Daama is nog agt ensiem-kOderende lokusse vir vyf rasse ontleed. Tussen 55 en 66.67% van die proteien-koderende lokusse was polimorfies (95% kriterium) vir al die rasse, behaiwe vir die • Namaqua skaapras wat slegs 33.33% polimorfies was. Die gemiddelde aantal allele per lokus wissel van 1.67 tot 2.5, en die gemiddelde heterosigositeit 'per lokus was 16.6 tot 35.9%. Die alleliese samestelling, veral by die, transferrien (TF) lokus het merkbare. verskille tussen die verskillende rasse getoon. Byvoorbeeld, die TF*H alleel was slegs by die Dormer skaapras gevind en die TF*G alleel in die Afrino, Van Rooy; Borderleichester, Swartkop-persie and Skilder-Persie rasse gevind. Die Suid Afificaanse Vleis Merino en Van RoOy rasse was die enigste polimbrfiese rasse by die albumien. lokus. Die alleliese samestelling by die res van die lokusse was soortgeyk vir al die rasse. Die Suid Afrikaanse Merino verskil by die TF lokus van Merino rasse in ander lande. Die genetiese afstand was die kleinste tussen die Dorper en Dormer rasse en die grOotste tussen die Romenof en Swartkop-persie rasse, met 'n gemiddelde genetiese afstand van 0.067 tussen die 19 rasse. Die gemiddelde hoeveelheid differensiasie tussen die rasse, relatief tot die:beperkte aantal onder algehele fticsasie (Fs r) was bereken as 0.123 vir polimorfiese lokusse, wat riaaiidniding -vari min genetiese differensiasie tussen . die rasse is. Merdie statistieke word egter the gereflekteer by al die lokusse wat bestudeer is the, deurdat 25 raspare (15%) van die totaal (171) the identiese alleel- verspreiding het nie. Geen van die raspare .het dieselfde alleelVerspreiding by al die lokusse getoon the; ten minste een lolcus het by:al die raspare verskillende alleelverspreidings getoon. RAPD'5 het. geen kthistante, herhaalbare resultate geleWer nie. Die resultate van die allosiem studie kan in teelProgranime gebruilc word en dit . is die eerste studie wat die huiding genetiese struktuur van die verskillende suider Afrikaanse skaaprasse aandui. Preface
This study was introduced at a local Departmental colloquium (30/09/1997) and it was presented at a National Conference (Sargent, J., Van der Bank, F.H. and Kotze, A., 1998. Genetiese variasie in die bloedproteiene van 19 skaaprasse van Suid-Afrika.
SA Tydskrif vir Natuurwetenskap en Tegnologie, 17:85), and also at a second departmental colloquium (07/10/1998). The results of this study were published in a national journal (Sargent, J., Van der Bank, F.H. and Kotze, A, 1999. Genetic variation in blood proteins within and between 19 sheep breeds from southern Africa.
South African Journal of Animal Science, 29(3): 245-257). This thesis is the final requirement to obtain a M.Sc. degree. AclulOwledgments My sincere gratitude is extended to the following people who contributed to the execution and completion of this project. Prof. F.H. van der Bank, my supervisor and mentor, for his time, guidance, assistance and constructive criticism throughout the duration of this project. Mrs. Antoinette Kotze, my co-supervisor, from the Animal Improvement Institute in Irene, for her patients and assistance in all aspects regarding the practical application of this study. Also for helping to initiate this study, and collect blood samples. Mrs. M. van der Bank for her comments, guidance and assistance in all respects regarding this study. Sasol who has provided financial funding and without whom this project wouldn't have been possible. All the farmers who supplied blood samples. RAU for giving me a much needed bursary to complete my studies MOST IMPORTANT I praise'the Lord for the privilege to study the complexity of His creation I would like to thank Charnay and Reino, my two children, for their love and patience. Last but not least, I am thanking my mother and farther, Myrtle and Patrick van goner, who always lead by example, even during times of hardship.
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:•,:-. CHAPTER 1
INTRODUCTION
CONTENTS: 1 — 1
Introduction 1 —2
Comparative characteristics and normal production environment of the sheep breeds studied:
2.1. Afrino 1 - 6 2.2. Blackhead Persian 1 — 7 2.3. Border Leicester 10 2.4. Damara 1-12 2.5. Dormer 1-14 2.6. Dorper 1-16 2.7. Karakul 1-18 2.8. South African Landskaap (No information) 2.9. Merino 1 — 21 2.100. Namaqua 1-24 2.11 Pedi 1-26 2.12. Perinoff (No Information) 2.13. Romanov 1 2. 28 2.14. Ronderib Afrikaner 32 2.15. Russian,Red Wooled Persian 34 2.16: Skilder Persian -35 2.17. South African Mutton Merino 36 2.18. Vandor 1-39 2.19. Van Rooy 1-41
The objectives of the study 1 — 42
1 - 1 INTRODUCTION
The archaeological record shows that domestic animals have been present in South Africa for almost 2 000 years. The first to arrive were sheep, goats and cattle, followed a little later by dogs, chickens and probably pigs. The earliest fossil record of sheep dates to about 2 000 years ago but sheep and goats separated about 5 million years ago. The fossil record is poor, probably because the normal habitat is unfavorable for fossil formation.
Sheep first appeared in the Villafranchian and from then on appeared sporadically in the
Pleistocene fossil record. Like many of the mammalian fauna of the ice ages, these were large animals that were later replaced by smaller mouflon-like animals. The animals were brought in by early communities migrating from the central lake area of Africa. They adapted to the environment and were able to thrive on poor grazing. These animals have become the indigenous breeds of southern Africa today. The total number of sheep worldwide was around 1087 million in 1994. There are 33 sheep breeds in southern
Africa, which include seven pure indigenous breeds (Terblanche, 1978). Indigenous breeds are defined as breeds with specific characteristics, etc. adapted to a specific environment..
The definition of a breed is either 1) a homogenous, sub specific group of domestic livestock with definable and identifiable external characteristics that enable it to be
separated by visual appraisal from other similarly defined groups within the same species,
or 2) a hothogenous group for which geographical separation from phenotypically similar groups has led to general acceptance of its separate identity. The Food and Agriculture
Organization of the United Nations (FAO) has adopted these definitions in its program on
animal genetic resources.
1 - 2 Indigenous breeds generally have a higher resistance against diseases, their adaptability to the warmer climate in the summer and extreme cold climate during the winter is better. Therefore, it is beneficial to characterize the indigenous sheep breeds and to use them in breeding programs to improve breeding stocks since a combination of different indigenous sheep breeds could lead to better utilisation of the natural resources, which would be economically viable (Tereblanche, 1978).
The domesticated sheep, Ovis aries, is classified as a member of the family Ovidae of the order Artiodactyla. The artiodactyls are one of the most successful of the mammalian orders, the genus Ovis is a good example of the arbitrary nature of classification at the species level, therefore the number of species, subspecies and races will alwa3is remain contentious.
The mechanisms of evolution that led to the development of, for example, wild
Sheep were mutations and chromosomal rearrangement,. selection, migration, geographical isolation and fixation of diversity by inbreeding and random genetic drift in small populations. Domestication increased the speed or the size of the effects of many factors, e.g. inbreeding, out breeding, genetic drift and added artificial selection and assertive mating to the forces changing gene frequencies. The change to domesticated conditions did not create any new inheritance, but the environmental changes following domestication allowed genetic differences to show themselves more clearly than before and thus to be more readily and accurately selected. Examples of important characteristics that can be mentioned include growth rate, fattening ability and milk yield, in which good feeding
1 - 3 increases differences. The change permitted a greater range of variation to survive through reduced natural selection.
Maintaining genetic variation within a pure breeding population is a complex . problem. A possible solution would be to determine the degree of distribution of the current genetic diversity, because no long-term management or meaningful conservation action can be taken without a complete understanding of the current genetic structure of a species. This is an important consideration since the existence of some of the indigenous sheep gene pools are threatened with exotics. The theoretical basis of this study is that breeds can be defined as populations, which differ from each other in the relative distribution and frequencies of genes (Hasselholt, 1969). These differences in allele frequencies indicate each breed's particular identity (Van Zeveren, 1995).
From the general description of immunological and electrophoretic polymorphisms, it appears that there are three characteristics in common which are of basic importance in view of practical applications, both in animal breeding and in fundamental research: a) the phenotype of an individual with respect to these traits does not change during life, b) it can be identified by objective methods of analysis and, c) it is controlled by simple Mendelian inheritance. For these reasons biochemical blood polymorphism was used to study the variability within populations and the divergence
between the different sheep . breeds. It is also a test based on the possibility of detecting inconsistencies between the genotype of an individual and those of the putative parents
An introduction to the sheep breeds studied follows.
1 - 4 2.COMPARATIVE CHARACTERISTISTICS AND NORMAL PRODUCTION ENVIRONMENT OF THE BREEDS STUDIED
The status, breed type and normal production environment of the sheep breeds studied are summarised in Table 1
Table 1. Sheep breed identification, status, breed type and normal production environment.
Sheep breed Status Breed type Production environment Afrino Adapted synthetic Wool and mutton Semi-Arid, Karoo breed breed veld Blackhead Persian. Indigenous Fat rumped breed Semi-arid, Cape Border Leicester Exotic Long wool breed Savannah Damara Indigenous Fat tailed breed Deserts, Namibia Dormer Adapted synthetic Mutton breed Temperate climate, breed whole South Africa Dorper Adaptive synthetic Mutton breed Arid grassveld, breed whole South Africa Karakul Indigenous Fat tailed breed Deserts, Namibia Landrace Exotic Mutton breed Cape Merino Adapted breed Wool breed Sour grassveld, semi-arid areas Namaqua Afrikaner Indigenous Fat tailed breed Karoo Pedi Indigenous Fat tailed breed NothernProvince Perinoff Adaptive Synthetic Mutton breed Karoo breed Romanov Exotic Mutton breed ARC — Irene Ronderib Afrikaner Indigenous Fat tailed breed Northern Cape Russian . Red Woolled Exotic Fat tailed breed Frankfort, Free Persian State Speckled or Skilder Indigenous Fat rumped breed • Dry areas, East Persian Africa South African Mutton Adapted synthetic Mutton breed High rainfall Merino breed grassveld Vandor Adapted synthetic Fat rumped breed Semi-arid grass to breed Karoo veld Van Rooy Adaptive synthetic Fat tailed breed Arid to semi-arid breed savannah, Cape
1-5 2.1 AFRINO
The Afrino is classified as an adapted synthetic wool and mutton breed. This refers to previous exotic breeds that adapted so well to their environment, that their genetic structure changed. The Afrino is a hardy sheep, which can withstand extreme dry conditions. This is a dual-purpose sheep breed. Its wool is a good export product and reaches high selling prices. An average of 3 kg of wool can be shaven off each individual.
Wool of an average of 21 micron can be produced and the meat of slaughtered lambs reaches a relatively high price at the meat market (Landbouweekblad, October 1997).
Right and above: Afrino rams (Landbouweekblad, October 1997).
1- 6 2.2 BLACKHEAD PERSIAN
The ancestors of the Blackhead Persian arrived in South Africa by chance and are one of
the oldest sheep breeds known. A trade ship trading with Arab, Persia and Africa had this
sheep as a slaughter breed on board when the ship broke down near Port Beaufort, close
to Swellendam on the Cape coast, in 1870. These sheep, one ram and three ewes, were
then purchased and taken to Wellington, where the breed was further developed. The
Blackhead Persian, Redhead Persian and Skilder Persian are therefore considered
indigenous (Campbell, 1995).
This breed is classified as a fat rumped breed and is one of the parent breeds of
the well-known Dorper. The Blackhead Persian is a fat rumped slaughter sheep. It has
low nutritional requirements, strong thick skin, short kempy fleece and a long breeding
season. The Persian shows some resistance against ticks and tick borne diseases and
thrive in the Uitenhage bushveld of the Eastern Cape, Savannah veldt. of the Northern