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Using the genetic markers to analyze
population genetic structure and
growth traits association in goat populations
Goat,Marker-assisted selection,Microsatellite marker,
|Publication Year :||2015|
|Abstract:||山羊為臺灣酪農產業中僅次於乳牛的重要乳品與肉品來源，又山羊肉相較於其他肉品，避免了文化與宗教因素的限制，因而逐漸為消費者所接受，開啟了透過人擇來篩選具有較優良生長性能山羊個體之選拔工作。由於我國本土山羊臺灣黑山羊（Taiwan black goat, TB）生長緩慢且產肉率低，因此透過引入外國品種山羊進行育種改良，然而大量雜交試驗與缺乏配套之本地黑山羊保育工作，導致本地黑山羊數量大幅銳減與遺傳歧異度流失，有鑑於本地黑山羊為臺灣之特有種，必須將其種源（germplasm）加以保育。近年來，分子標識已廣為應用於評估物種間之遺傳變異與供分子育種之用途，本研究目的為利用分子標識，分析包含臺灣黑山羊之族群遺傳結構與生長性狀之相關性，以兼顧種源的保存以及培育優良種源之目標。|
本研究蒐集來自 10 個山羊族群共 682 頭山羊之血樣，以 15 組微衛星標識進行遺傳變異分析，試驗結果顯示，在所檢測的山羊族群，平均交替基因數（average number of alleles , Na）與有效交替基因數（effective alleles , Ne）分別為 11.87±3.40 及 5.1±1.80；平均期望異質度（average expected heterozygosities, HE）與觀測期望異質度（observed heterozygosities, HO）分別為 0.781±0.081與0.602±0.116；平均多態性訊息含量（polymorphic information content, PIC）為 0.747±0.103；FIS 的範圍從 -0.034至0.215 之間，平均值為 0.058，顯示所有的微衛星標識在所檢測的族群中皆具有多態性（polymorphism），且所有試驗族群已有近親之現象。進一步使用 Nei (1972)法計算各族群間遺傳距離矩陣並以鄰近相接法(neighbor-joining, NJ)繪製親緣關係樹(phylogenetic tree)，結果顯示可將臺灣黑山羊族群與其他山羊族群進行分群(clustering)，且臺灣黑山羊種源於恆春分所保存完善。此外，本研究另選擇對生長具有影響之候選基因，進行基因型與諸在養山羊生長性狀之相關性分析，包含 MSTN g.1256TTTTA/-、POU1F1 g.102T>G 與 IGFI g.282G>C三組 SNP 標識，並蒐集 497 頭努比亞山羊於出生、三月齡（離乳）、六月齡、九月齡及十二月齡之體重（body weight, BW）、體高（body height, BH）、體長（body length, BL）及胸圍（body chest girth, BCG）之測量值，並計算各生長階段之平均日增重（average daily gain, ADG），結果顯示，三組 SNP 標識皆對努比亞生長性狀具有顯著地相關性。帶有 MSTN 基因之 BB 基因型個體於 BCG0、ADG6、BW6和 ADG9 顯著地高於其他基因型（P < 0.05）；帶有POU1F1 基因之 D1D1 基因型個體於 BH6、BL6、BCG6、BW9、BH9、BL9、BCG9、BL12 和 BCG12顯著地高於其他基因型（P < 0.05）；帶有 IGFI 基因之 CC 基因型個體則在 BW0、BL0、BCG0、BH6、BL、 BCG6、BL9、BCG9、BH12 和 BL12 顯著地高於其他基因型（P < 0.05）。
綜合所述，本試驗所使用之微衛星標識，可應用於臺灣黑山羊及其雜交族群之遺傳結構分析，可供未來種源與保育工作之參考依據。同時，本試驗提供對提升生長性狀具有顯著效應之三組 SNP 標識，可進一步應用於臺灣肉用山羊之育種用途。因此，透過分子標識輔助選拔（marker-assisted selection, MAS），可加速更有效率且精確之保種與育種標的。
Goat was an important source of milk and meat in addition to cow in dairy farming in Taiwan. Goat meat has becoming much more acceptable to consumers without regards of cultural and religious barriers. Therefore, selection of goats to improve growth traits was brought into action. Due to the poor growth rate and meat yield of Taiwan black goat (TB) breed in Taiwan, many exotic breeds were brought into breeding scheme to improve their growth trait. However, excessively crossbreeding alien species with TB decreased its population and their genetic variation, so which was considered as an endemic species in Taiwan that needed to be preserved. In recent years, the genetic markers were studied and applied in domestic animals, aiming at evaluating and selecting across breeds. Hence the objective of this study is using genetic marker to analyze genetic structure and its growth performance in Taiwan, setting the purpose of genetic improvement as well as to sustain the germplasm preservation.
There were 15 sets of microsatellite markers used for analyzing 682 goats that sampled from 10 populations. The average number of alleles (Na) and effective alleles (Ne) were 11.87±3.4 and 5.1±1.8. The average expected heterozygosity (HE) and observed heterozygosity (HO) per locus were 0.781±0.081 and 0.602±0.116. Average polymorphic information content (PIC) was 0.747±0.103. FIS was 0.747. The results showed that 14 sets of microsatellite markers were highly polymorphic. The genetic distances between individuals were estimated using the method of Nei (1972) and followed by construction of phylogenetic tree using neighbor-joining (NJ) methods. The results indicated that these 15 sets of microsatellite markers were proved to successfully recognized different populations included. The germplasm of TB was still well-preserved in Hengchun Branch, LRI, C. O. A. Meanwhile, there were 3 single nucleotide polymorphism (SNP) markers being selected for analyzing their association with growth traits of Nubian goats in Taiwan. They were MSTN g.1256TTTTA/-, POU1F1 g.102T>G and IGFI g.282G>C according to their association with various productivity traits studied by several authors. In this trial, 497 Nubian goats were sampled. Growth traits data including body weight (BW), body length (BL), body height (BH), and body chest girth (BCG) at birth, weaning, 6-month-age, 9-month-age and yearling were collected. The average daily gain (ADG) at birth to weaning, weaning to 6-month-age, 6-month-age to 9-month-age and 9-month-age to yearling were also calculated, respectively. The association analysis revealed that 3 SNP markers had significantly effects. Individuals with BB genotype of MSTN gene showed better growth traits at BCG0, ADG6, BW6, and ADG9 among three genotypes (P < 0.05). Individuals with D1D1 genotype of POU1f1 gene showed better growth traits at BH6, BL6, BCG6, BW9, BH9, BL9, BCG9, BL12 and BCG12 among three genotypes (P < 0.05). Individuals with CC genotype of IGFI gene showed better growth traits at BW0, BL0, BCG0, BH6, BL6, BCG6, BL9, BCG9, BH12 and BL12 among three genotypes (P < 0.05).
Overall, these 15 sets of microsatellite markers we used could apply for TB as well as hybrid goat population genetic structure for future conservation guidance, while growth traits association test also showed all three SNP markers have remarkable effects on it, provided practical application for meat goat breeding in Taiwan. As a result, marker-assisted selection (MAS) will promote rapid efficient breeding and selection of goat.
|Appears in Collections:||動物科學技術學系|
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