Comprehensive Genetic Analysis with Mitochondrial DNA Data Reveals the Population Evolution Relationship Between Chinese Gamecocks and Their Neighboring Native Chicken Breeds
With the aim of testing whether there are possible genetic communications between Chinese gamecocks and their neighboring native chicken breeds, this study comprehensively analyzed an integrative mitochondrial DNA (mtDNA) data of 328 chicken (69 gamecocks belonging to 5 breeds and 259 domesticated chicken belonging to 18 breeds). Analysis of Molecular Variance (AMOVA) and phylogeny demonstrated Chinese gamecocks formed monophyletic groups that had been differentiated significantly with other native chicken breeds, though some of the clusters appeared to be an admixture of gamecocks and domesticated chicken. All the analysis demonstrated significant differentiation within chicken populations sampled and presented a gene flow mode of geographical distribution (p<0.05, AMOVA). In this study, we found most of the chicken breeds have been an admixture with possible gene flow among them, except for three gamecock breeds and three native chicken breeds, Chahua, Gushi and Tibetan chicken, whose races are relatively pure. Our study provided important clues for the research and understanding of the evolutionary and genetics relationship among Chinese native chicken breeds.
The domestication of chicken is often associated with the progression of human
society and culture. Domestic chicken are now distributed all over the world
and generally being classified into four categories, such as entertainment,
ornamental, meat and egg production according to their utilities for human.
Domestic chicken were believed to have been originated from the red jungle fowl
(Gallus gallus) as early as 5400 B.C. (Zeuner, 1963;
West and Zhou, 1989) with archaeological discoveries
in the regions of Indus Valley and Hebei Province of China, respectively.
There are five possible progenitor subspecies of the red jungle fowl G.g.
gallus (Gallus gallus gallus) in Thailand and its adjacent regions,
G.g. spadiceus in Burma and Yunnan Province of China, G.g. jabouillei
in Southern China and Vietnam, G.g. murghi in India and G.g. bankiva
in the Java islands (Crawford, 1995; Howard,
1984) and presently researchers defend two hypotheses on the origination
of domestic chicken: monophyletic origin of chicken from the G.g. gallus
in Thailand and the Indus valley (Fumihito et al.,
1994, 1996) and multiple origins of chicken from
the G.g. gallus with independent domestication incidences in different
regions (Crawford, 1990, 1995;
Liu et al., 2006a). Liu
et al. (2006a) made the first large scale analysis of the mitochondrial
DNA hyper-variable segment I (HVS-I) from 834 domestic chickens (Gallus gallus
domesticus) sampled across Eurasia with 66 wild red jungle fowls (Gallus
gallus) from Southeast Asia and China. Their phylogenetic analysis revealed
a dispersal pattern of nine highly divergent mtDNA clades (A-I) for both the
red jungle fowls and domestic chickens, but there was no breed-specific clade
in the study.
Although, the academic viewpoint of chicken multiple maternal origins seems
ready to be acceptable, it is not yet known how many subspecies of the red jungle
fowl have contributed to the origination of some particular chicken breeds,
such as gamecocks. The authors also admitted that they failed to identify breed-specific
matrilineal clades in their study (Liu et al., 2006a)
and most of their samples from China were distributed in Yunnan Province and
the adjacent provinces. Their speculation about the clade D which mainly contained
red jungle fowl and gamecocks was still in need of verification. Until now,
we have no direct or clear evidence about the gene flow between the wild red
jungle fowl and gamecocks and it is natural to make a survey on the relationship
between the Chinese gamecocks and other native chicken breeds in adjacent areas
with integrative historical records and genetic data.
There are many historic records or biographies describing the ancient cockfighting
in China (Xie, 1980, 1992; Zhu,
1999). Its true that the Japanese envoi went to China and returned
Japan with the gamecocks and spreading the cockfighting culture ever since in
the Tang Dynasty, approximately 1300 years ago (Xie, 1980,
1992). It was believed that China was one of the earliest
ancient nations raising cocks for cockfighting and the cockfighting culture
originated in China and dispersed to East and Southeast Asia. Since, the introduction
of gamecocks was believed to be associated with culture communication and the
national historical stories, tracing the origin of gamecocks could thus provide
key clues on the spreading of cockfighting games and its culture among different
countries and/or regions.
According to cockfighting game players, ancient people used fighting cocks
to resolve disputes at an earlier time. Later, people found it interesting to
make cocks fight with each other and created the cockfighting games. Therefore,
gamecock was bred from domestic chicken and isolated for special fighting trainings.
There should not be any genetic communications between gamecocks and other chicken
breeds. However, according to some historic documents or records, it was assumed
that the famous Shouguan chicken and some other breeds were the decedents of
Chinese Luxi gamecocks from ancient Qi kingdom at the Chun Qiu Period (770-476
B.C.) (Xie, 1980). The famous breed Shouguang chicken
in Shandong Province of China had been formed and was once trained and exploited
as cockfighting chicken during the Northern and Southern Dynasties Period of
China (420-589 A.D.). It is also meaningful to trace the relationship between
the Shouguang chicken and Luxi gamecock using mitochondrial DNA (mtDNA) data.
Recently, Komiyama et al. (2003) analyzed 47
gamecock mtDNA data (42 from Japan, 2 from Myanmar and 3 from China) and suggested
a dual origin of Japanese gamecocks, with one arising from mainland China and
the other from Southeast Asia (Komiyama et al., 2003).
They further analyzed the relationship of Japanese domesticated chicken and
gamecocks and suggested that most of the Japanese domesticated chicken have
been derived from the ancestors of Japanese gamecocks (Komiyama
et al., 2004). Liu et al. (2006b) also
analyzed the 42 Japanese gamecock mtDNA data, adding 52 Chinese gamecock mtDNA
sequences and advocated a single origin hypothesis of the Japanese gamecock
from China (either directly from China or indirectly via Southeast Asia). Other
than this, they had no more discussion on the population differentiation or
gene flow among chicken populations in relation to Chinese gamecocks. Qu
et al. (2009) analyzed the genetic relationships among Chinese gamecock
breeds with mtDNA data and proposed that gamecock breeds might originated from
domestic chicken or wild birds directly, but their suggestion was not convincing
since no evidence from red jungle fowls and other domestic chicken was demonstrated.
Moreover, these authors had not analyzed the relationship of Chinese chicken
breeds and gamecocks, or testing the hypothesis that there are possible genetic
communications or hybridizations between Chinese gamecocks and their neighboring
chicken breeds, as Komiyama et al. (2004) did
in Japanese indigenous chicken.
In this study, we compared the first hyper-variable segment I sequences of
the mtDNA control region (HVS-I) of 69 gamecocks belonging to 5 breeds across
China and 259 native chicken belonging to 18 breeds sampled from the neighboring
regions or provinces, with sequences data retrieved from GenBank and previous
works (Niu et al., 2002; Komiyama
et al., 2003; Liu et al., 2004; Qu,
2004; Liu et al., 2006b; Song,
2006; Bao, 2007). First, we constructed phylogenetic
trees and compared the mtDNA data of Chinese gamecocks with the neighboring
native breeds using the red jungle fowls as the outgroup, in order to trace
and learn more about the genetic information between Chinese gamecocks and the
neighboring native chicken breeds and the followed artificial selection. Then,
we analyzed the gene flow at an inter-group level and computed the corresponding
population differentiation, particularly focusing on Chinese gamecocks. We found
most of the chicken breeds have been an admixture with possible much gene flow
among them, except for three gamecock breeds and three native chicken breeds.
We also found there was no obvious genetic evidence for the assumption that
the Shouguan chicken breed was descended form Chinese Luxi gamecocks.
MATERIAL AND METHODS
The sample data were collected and the research project was conducted from
October, 2007 to November, 2009, with two necessary updates in mid 2009. We
retrieved 69 Chinese gamecock mtDNA data, in which 62 were from GenBank (accession
No. AY588608-42, AB098664-6, AY465968-71, AF512108-16, DQ462521-5, DQ462547-9,
DQ462551-2) and 8 were provided by Bao (2007), (Henan
gamecock, recoded as HnDJ013-20). Then, we got a total of 258 Chinese native
chicken mtDNAs belonging to 18 breeds in the neighboring regions, some from
GenBank (accession nos. AY465960-6, AY465972-9, AY465981-007, AF512076-90, DQ462526-46,
DQ462550, DQ462553-6, DQ462563-70, AF128315-24, AF128330-4, AF128340-4), the
rest were provided by Bao (2007) and Qu
(2004). The reported 15 mtDNAs of red jungle fowls (8 from China and 4 from
Thailand, Bao 2007; another 3 strains are from Indonesian,
accession No. AB007718, AB007720 and AB009431; Komiyama
et al., 2003) were also compiled and put into analysis. Detailed
sample information is presented in Table 1.
Among all the reported sequences, two (Accession No. AY588607 and AY465967)
were deleted and not included in the following analysis as suspected of sequencing
errors (Liu et al., 2006a). It should be noted
that, in the study of Liu et al. (2006a), their
samples from China were mainly from Yunnan Province and adjacent provinces (415
out of 595, or about 74.21%) and the clade D were mainly composed of red jungle
fowl and gamecocks (Liu et al., 2006a).
||Genetic diversity of Chinese native chicken samples
|The estimation is restricted to the 516 bp fragment relative
to sequence position 1-516 of mtDNA HVS-I region
Sequences (gamecocks and the other native chicken) were aligned and the
nucleotide polymorphisms were reported using MEGA version 4.0 (Tamura
et al., 2007). We discarded any insertions/deletion (e.g., indel) in
the following analysis. First, we constructed rooted NJ (neighbor-joining) trees
for Chinese gamecocks with Indonesian red jungle fowls as outgroup and unrooted
NJ trees for the haplotypes shared by Chinese gamecocks and their neighboring
native chicken breeds considered in this study by means of Kimura two-parameter
model. We validated phylogenetic trees with interior branch bootstrap test of
1,000 replicates to create second trees respectively. We focused interests on
the main clades emerging from the trees.
Meanwhile, the genetic relationships of tree clades were further explored by
median-joining method (Bandelt et al., 1999).
The graphic median-joining (MJ) networks were drawn according to Bandelt
et al. (1999, 2000) and confirmed using Network
To learn more about the genetic diversity of the gamecock, we estimated haplotype
diversity (h) and nucleotide diversity (ð) for samples from each breed and
two serials of samples from assembled breeds using DnaSP version 4.0 (Rozas
et al., 2003).
Population Differentiation and Gene Flow
Population comparison and population differentiation were executed in an
integrated group or a few groups in different geographic regions with gamecocks
and the neighboring native chicken breeds as populations or subgroups, computing
gene flow and genetic differentiation with haplotype genotypic data in the software
package ARLEQUIN version 3.11 (Excoffier and Schneider,
2005). Inter-group level analysis, such as analysis of molecular variance
(AMOVA), estimates of pairwise genetic fixation indices (Fst) and gene flow
indices (Nm), were calculated for evaluating the evolutionary relationship among
different Chinese chicken breeds.
First, we used the structure package version 2.3.1 (Pritchard
et al., 2000; Falush et al., 2003)
to infer the proper number of populations and assumed a mode with population
admixture and that the allele frequencies were correlated within populations
(Falush et al., 2003). We conducted 10 independent
runs for each value of K (the number of subpopulations) between 1 and 23. After
conducting numerous runs to investigate the behaviour of the programme, we chose
to use a burn-in period of 104 iterations and then collect data for
105 iterations. We ran the software also with the same parameters
separately for both Gamecocks and their neighboring chicken samples. The presence
of genetic structure among the Chinese native chicken populations was investigated
also by an analysis of variance framework using analysis of molecular variance
(AMOVA). We next used the ARLEQUIN package version 3.11 (Excoffier
and Schneider, 2005) to perform the AMOVA analysis.
We used both softwares ARLEQUIN and DnaSP to estimate each pairwise genetic
distances (Fst) and the corresponding estimate of the average effective number
of migrants (Nm) exchanged among the Chinese 5 gamecock breeds and 23 native
chicken populations. Exact tests of population differentiation between the chicken
populations were conducted as described by Raymond and Rousset
(1995) using ARLEQUIN with 10000 markov chain interactions.
It should be noticed that the estimates of Nm are based on the island mode
of population structure (Wright, 1951; Nei,
1987), where N is the number of individuals in each subpopulation sampled
and m is the fraction of migrants in each subpopulation in each generation.
For instance, Fst = 1/(1 + 2Nm) on haploids (mitochondrial and chloroplast genomes)
and Fst = 1/(1 + 4Nm) on diploids (autosome), or Fst = 1/(1 + 3Nm) on diploids
(X-chromosome), or Fst = 1/(1 + Nm) on diploids (Y-chromosome). If Fst is less
than or equal to 0, the estimator is considered undefined and not analyzed later.
Sequence Variation and Genetic Diversity
The mtDNA sequence variations of 69 Chinese gamecocks and 259 the other
Chinese native chickens are shown Table 1. An integrated population
group of 328 chicken belonging to 5 gamecock breeds and 18 native chicken breeds
was further analyzed with phylogenetic tree and supported by graphic profiles
of MJ network, although some distances between nodes were only one or two mutation
In total, we had identified 59 variable sites which defined 60 haplotypes in
the integrated large population group (detailed information could be showed
if demanded), where single variable sites were identified in 32 loci. Statistics
of all the haplotypes and nucleotide diversities were summarized in Table
1. Among five Chinese gamecock breeds, Tulufan and Banna (Xishuangbanna)
samples have high haplotype diversities (h = 1.000±0.096 and h = 0.901±0.059,
respectively), Banna gamecock samples have a high nucleotide diversity (π
= 0.01167±0.00259), whereas Zhangzhou samples show the lowest haplotype
and nucleotide diversities (h = 0.286±0.196, π = 0.00278±0.00191).
The average genetic diversity of Chinese gamecock samples (h = 0.906±0.018,
π = 0.01499±0.00137) is relatively higher than that of the other
Chinese native chicken samples (h = 0.870±0.013, π = 0.00795±0.00037).
Phylogenetic Tree and MJ Network Profile Show Geographical Distributions
Phylogenetic trees were built with mtDNA haplotypes of all the Chinese native
chicken samples and red jungle fowls. Clear clades could be figured out. Eleven
main clades or nodes (A-K) are discerned in both the unrooted NJ tree and MJ
network built with mtDNA haplotypes of Chinese gamecocks and the neighboring
chicken breeds (Fig. 1, 2). The NJ tree
was bootstrapped with 1000 replicates and the haplotype clades were further
supported by the MJ network profile (Fig. 2), which has been
widely used in reconstructing maximum parsimony phylogenies for intra-specific
mtDNA data (Bandelt et al., 1999).
The first NJ phylogenetic tree was constructed after analyzing an integrative
set of 328 sequences from Chinese gamecocks and the neighboring native chicken
breeds (Fig. 1). This NJ phylogeny tree recovered 60 haplotypes
for all the Chinese native chicken within 11 clades partitioned according to
the cluster shapes. In general, the alleged Central Chinese gamecocks (including
Luxi and Henan gamecock breeds) differ from other Chinese chicken breeds and
cluster together by harboring a high amount of lineages in clades B, G and H,
whereas the majority of lineages in Chinese gamecocks present (Fig.
1, Table 1). The Henan and Banna gamecocks got an admixture
cluster in both two sets of trees, while the majority of Luxi gamecocks did
not join in other chicken lineages except Henan gamecocks (Fig.
2, Table 1). It shows the Central Chinese gamecock lineages
are relatively conserved. The NJ tree was supported by MJ network profiles very
well (Fig. 2). It was also seen that Zhangzhou gamecocks were
isolated from the other gamecocks (Fig. 2). Moreover, clades
or nodes in Fig. 1 and 2 are in accord with
the geographical distribution of the Chinese native chicken lineages. For instance,
Luxi gamecocks from Shandong Province are clustered more close to chicken breeds
from Shandong Province and the neighbor Jiangsu and Henan Provinces. Tibetan
chicken comprise lineages close to Chahua chicken sampled from the neighboring
||NJ tree of 60 mtDNA haplotypes for Chinese gamecocks and their
neighboring native chicken. Eleven clades of mtDNA haplotypes (coded as
hap) were found in the phylogenetic tree
Genetic Structure and (AMOVA) Analysis of Chinese Chicken Population
Phylogenetic analysis can provided the clustering of clades with sequence
similarity, but it brings no more population information to us, such as the
population structure and differentiation. So, we analyzed the genetic structure
among Chinese chicken populations, including gamecock breeds.
In the Bayesian analysis of population structure (significance tests at 1023
permutations) (Pritchard et al., 2000; Falush
et al., 2003), the probabilities of six clusters (K = 1-6) were
relatively high and the variants of LnP(D) with K cluster values belonging to
different samples were the lowest ones (Fig. 3).
||MJ network profile of 60 mtDNA haplotypes of the Chinese gamecock
and the neighboring native chicken. The codes of LxDJ, HnDJ, BnDJ, TlfDJ
and ZzhDJ stand for five gamecock breeds in China, while the codes of RDch,
RDth and RDini mean red jungle fowls from China, Thailand and Indonesian,
respectively. The codes of Ber, BJY, ChH, DaG, GuS, HeT, JnBr, LanY, LinK,
LSH, LuY, LwuB, QYB, ShG, Tib, WuG, XJu, XSH are the other 18 Chinese native
chicken breeds, i.e., Baier, Beijingyouji, Chahua, Dagu, Gushi, Hetian,
Jiningbairi, Langya, Lingkun, Lanshan, Luyuan, Laiwu Black, Qinyuan Blot,
Shouguan, Tibetan Chicken, Wugu (Silk), Xianju, Xiaoshan stand for five
gamecock breeds, respectively
According to the plot Figure (Fig. 3), the most probable
number and sub-structuring mode of population groups was five. AMOVA analysis
with five geographical distributing sub-groups (we selected five vicinal areas,
e.g., Shandong and neighboring regions, Fujian and neighboring regions, Yunnan,
Xinjiang and Tibietan) suggested no significant differentiation among the five
population groups of Chinese gamecock and their neighbor native chicken (p =
0.58651±0.01888), but significant differentiations within populations
(p<0.001) and among populations within groups (p<0.001) (Table
2). Most of the variation (83.12%) appeared to be within populations and
the rest appeared to be among populations within groups (16.88%) (Table
2). No variation was found to be within groups since the F statistics of
variation base on haplotype frequencies turned out to be negative and was denied.
According to the plot of structure mode choice criterion LnP(D) (Fig.
3), the STRUCTURE analysis with both Chinese gamecocks and the native chicken
might suggest some other possible substructures grouping in all the chicken
populations with lower LnP(D) values too.
We also did the AMOVA analysis of two groups of Chinese gamecocks and the other
native chicken, assuming Chinese gamecocks were isolated from the other populations
sampled. The overall genetic differences of Chinese gamecocks and their neighbor
chicken populations suggested a near significant differentiation among these
two population groups (p = 0.05963±0.00883, F-statistics of variation
based on haplotype frequencies and 1023 permutations, Table 2).
||Mode choice criterion Ln P(D) of the structure for each k
cluster value. The k cluster value is an index for mode selection in STRUCTURE.
The structure algorithm starts at a random place in parameter space and
then converges towards a mode of the parameter space. In this context, a
mode can be thought of as a clustering solution that has high posterior
||AMOVA Analysis of five groups computed based on conventional
F-Statistics of haplotype frequencies (significance tests at 1023 permutations)
||AMOVA Analysis of two groups computed based on conventional
F-Statistics of haplotype frequencies (significance tests at 1023 permutations)
Most of the variation (81.61%) appeared to be within populations and the rest
appeared to be within groups (2.31%) and among populations within groups (16.08%)
(Table 3). However, the variation between population groups
was near significant (p = 0.05963±0.00883) and explained 2.31% of the
total variation and the Fst estimate of 0.26258 would suggest Nm = 1.40418 as
the average effective number of migrants exchanged per generation between the
The pairwise estimates of Fst among chicken breeds or populations suggested
that the chicken populations are genetically close to each other (Fst and Nm,
Appendix 1). Some Fsts are less than 0, these estimators are undefined and not
considered. The pairwise estimates and non-differentiation exact test (see the
p-values matrix, significance level at 0.05, markov chain length 10000 steps)
provided us useful clues to infer the population differentiation and gene flow.
Simulation Analysis of Gene Flow and Population Differentiation Test
The pairwise Fst matrixes estimated by ARLEQUIN and DnaSP are similar (Weir
and Cockerham, 1984; Wright, 1951), but Fst values
provided by ARLEQUIN are much lower than those by DnaSP and probably would lead
a set of higher Nm estimates. Here, we consecutively took the pairwise Fst and
Nm estimates matrix computed by ARLEQUIN to infer whether there is any possible
genetic spreading or gene flow between Chinese gamecocks with the other Chinese
native chicken breeds and made the non-differentiation exact test (p<0.05,
p-values can be found in Appendix 2).
Finally, we tested the hypothesis of random distribution of the individuals
between pairs of populations in the simulation as described in Raymond
and Rousset (1995) and Goudet et al. (1996).
This test is analogous to Fishers exact test on a two-by-two contingency
table, but extended to a contingency table of size two (Raymond
and Rousset, 1995). All pairs of samples were taken into a non-differentiation
test with 10000 markov chain steps done and the exact simulated p-value matrix
of pairwise Fst estimates was produced with 6000 markov chain steps. The p-values
with sign + showed differentiation and p-values with sign - showed non-differentiation
at the significance level of 0.0500.
Liu et al. (2004) and Song
(2006) analyzed the genetic diversities with mtDNA data of a number of Chinese
native chicken breeds, including 4 Henan and 9 Luxi gamecocks, but their sample
sizes were small and could not resolved the issue whether there are possible
genetic communications between Chinese gamecocks and their neighboring chicken
breeds. Liu et al. (2006a) made a large scale
phylogenetic analysis of the mtDNA data from 834 domestic chickens, but there
were no breed-specific clades. The authors acknowledged that they failed to
identify breed-specific matrilineal clades in their study (Liu
et al., 2006a). Their speculation about the clade D which mainly
contained red jungle fowl and gamecocks was still in need of verification. Later,
Liu et al. (2006b) analyzed 42 Japanese gamecock
mtDNA data and 52 Chinese gamecock mtDNA sequences and advocated a single origin
hypothesis of the Japanese gamecock from China. Qu et
al. (2009) proposed that gamecock breeds might originated from domestic
chicken or wild birds directly, but their suggestion was not convincing since
no evidence from the other domestic chicken was demonstrated. However, these
authors had no more discussion on the population structure or gene flow within
Chinese gamecocks. They also had not fully analyzed the relationship of Chinese
gamecocks and other native chicken breeds, as Komiyama et
al. (2004) did in Japanese indigenous chicken. In the present study,
we comprehensively tested the hypothesis whether there are possible genetic
communications between Chinese gamecocks and their neighboring native chicken
breeds and found a worrying situation for Chinese gamecocks. Moreover, we found
there was no obvious genetic evidence to verify the relationship that the Shouguan
chicken breed was probability descended form Luxi gamecocks.
In the present analysis, we focused on the impact of population differentiation
and admixture of Chinese gamecocks with other chicken breeds, which could be
inferred from the AMOVA and phylogeny and population simulation analysis with
significance level of the p-values. Analysis of the matrix data in Appendix
1 and 2 provided a perspective on the pattern of gene flow among Chinese native
chicken breeds. Besides the Central Chinese gamecocks, there are some chicken
breeds also show independent differentiation, such as Chahua and Gushi chicken.
Apart from the Chinese gamecocks, most of the p-values of non-differentiation
in the neighboring native chicken demonstrated a mode of geographical distribution.
In the five regional group AMOVA analysis, observed haplotype frequencies are
well according with expected haplotype frequencies under the infinite-allele
model (data not showed). At present, we can not confirm the Shouguan chicken
were the decedents of Chinese Luxi gamecocks. As expected, Luxi gamecocks are
significantly differentiated from the other chicken breeds and the hypothesis
that Shouguan chicken are the descendent of ancient Luxi gamecocks thus found
no evidence in our analysis. The Central Chinese gamecock were independently
raised and mated without admixture, which was supported by both phylogenetic
analysis and pairwise population differentiation tests.
Another obviously independently differentiated breed is Zhangzhou gamecocks
whose exact p-values appear to be significantly differentiated from other chicken
breeds. Different from Bannan and Tulufang gamecocks, the Zhangzhou gamecocks
were original from Southeast Asian by trade ships. The Zhangzhou trade ships
and ports, thriving in the Ming Dynasty, linked the region to many areas through
trade. These trade links allowed for gamecock transport and admixture with many
Southeast Asian gamecock breeds (Wu, 1983), contributing
to the unique genetic background of Zhangzhou gamecocks. Bannan gamecocks were
reported to be frequently mixed other fighting cocks or roosters, such as Thailand
and Myanmar (Burma) gamecocks. Tulufang gamecocks were thought to be the intercrossing
descendent of Central Chinese gamecocks and Russian chicken. Origins of these
three gamecocks are rather complex. Now, Tulufang gamecocks are becoming extinct.
These analysis also suggest these two gamecock breeds are badly in need of conservation,
though the Central Chinese gamecocks are relatively isolated and prosperous
In China, gamecock (called Douji) is reared solely for use in cockfighting
and as pets. The tradition of cockfighting can be traced to as early as 2500
years ago (Xie, 1980, 1992;
West and Zhou, 1989; Zhu, 1999).
Gamecock and cockfighting pictures found on some archaeological assemblages
can date to 45-23 B.C. (Xie, 1980, 1992;
Zhu, 1999), e.g., the stone picture of a woman feeding
two gamecock-like chicken found in the Dazu district of Chinese Sichuan Province
and the unearthed copper and crockery vases of approximately 2000 years ago
displaying cockfighting scenes (Zhu, 1999). On the top
of a vase copper excavated in the grave of Jiangsu Province of China, a small
sculpture as gamecock-like creature was discerned (Xie,
1980, 1992; Zhu, 1999).
Popularity of cockfighting in history undoubtedly contributed to disperse these
ancient chickens geographically. The number of gamecocks has increased during
the past 20 years in China since the cockfighting game or culture returns to
be popular accompanying the Chinese increasing economic circumstances. At present,
there are five long-time formed breeds, i.e., Luxi gamecock, Henan gamecock,
Banna gamecock, Tolufang gamecock and Zhangzhou gamecock. The former two breeds,
whose breed numbers are presently estimated each at near 100000, made up the
so-called Central Chinese gamecocks, while those of the latter three breeds
are estimated at about 10000, 3000 and 20000, respectively.
However, the Chinese gamecock breeds are badly in need of conservation now.
The fairly high artificial selection and reproductive isolation of Chinese gamecock
populations suggested that each population should be restricted to a genetic
pool and vulnerable to harmful effects of inbreeding. Tulufang gamecocks have
been threatened with extinction and had a relatively reduced scale due to geographical
isolation and inbreeding, while Banna gamecocks were considered as heterozygous
and attribute to much mixture with foreign fighting cocks. Present analysis
and collected data of long term gene flow showed that many of the Chinese native
chicken colonies could no longer be viewed as separate entities, though five
geographical distributions could be discerned. On the contrary, many chicken
breeds are considered to be declined because of extensive introduction and admixture.
Recently, the popularity of cockfighting was increasing in China and many breeders
have introgressed gamecock breeds from other provinces and even nations in order
to improve their gamecocks fighting traits. This recent admixture could
account for the lack of monophyletic haplotype groups and a decline trend, as
well as high genetic diversities.
This study was supported by grants from the National Basic Research Program
of China (2006CB102101).
||Table of Fsts (below diagonal) and Nms (above diagonal)
|If Fst was less than or equal to 0, the estimator was considered
undefined and not studied in the Nm analysis (noted as n/m)
||Table of markov simulated p-values (below diagonal) and
significant differences (above diagonal) of non-differentiation exact
|All pairs of samples were taken into a non-differentiation
test with 10000 markov chain steps done and the exact p-value matrix of
pairwise Fst estimates was produced with 6000 markov chain steps. The
p-values with sign + showed differentiation and p-values with sign - showed
Bandelt, H.J., P. Forster and A. Rohl, 1999.
Median-joining networks for inferring intraspecific phylogenies. Mol. Biol. Evol., 16: 37-48.PubMed | Direct Link |
Bandelt, H.J., V. Macaulay and M. Richards, 2000.
Median networks: Speedy construction and greedy reduction, one simulation and two case studies from human mtDNA. Mol. Phylogenet. Evol., 1: 8-28.CrossRef | PubMed |
Bao, W.B., 2007.
Analysis of genetic diversity and phylogenetic relationship among chinese domestic fowls and red jungle fowls. Ph.D. Thesis, Yangzhou University, China.
Crawford, R.D., 1995.
Origin, History and Distribution of Commercial Poultry. In: Poultry Production, Hunton, P. (Ed.). Elsevier, Amsterdam, pp: 1-20
Excoffier, L.L.G. and S. Schneider, 2005.
Arlequin ver. 3.0: An integrated software package for population genetics data analysis. Evol. Bioinform. Online, 1: 47-50.Direct Link |
Falush, D., M. Stephens and J.K. Pritchard, 2003.
Inference of population structure using multilocus genotype data: Linked loci and correlated allele frequencies. Genetics, 164: 1567-1587.PubMed | Direct Link |
Fumihito, A., T. Miyake, S. Sumi, M. Takada, S. Ohno and N. Kondo, 1994.
One subspecies of the red junglefowl (Gallus gallus gallus
) suffices as the matriarchic ancestor of all domestic breeds. Proc. Natl. Acad. Sci. USA., 91: 12505-12509.PubMed | Direct Link |
Fumihito, A., T. Miyake, M. Takada, R. Shingu and T. Endo et al
Monophyletic origin and unique dispersal patterns of domestic fowls. Proc. Natl. Acad. Sci. USA., 93: 6792-6795.PubMed | Direct Link |
Goudet, J., M. Raymond, T. de Meeus and F. Rousset, 1996.
Testing differentiation in diploid populations. Genetics, 144: 1933-1940.PubMed | Direct Link |
Howard, R., 1984.
A Compete Checklist of Birds of the World. Oxford University, New York, pp: 701Direct Link |
Komiyama, T., K. Ikeo and T. Gojobori, 2003.
Where is the origin of the Japanese gamecocks? Gene, 317: 195-202.CrossRef | PubMed | Direct Link |
Komiyama, T., K. Ikeo, Y. Tateno and T. Gojobori, 2004.
Japanese domesticated chickens have been derived from Shamo traditional fighting cocks. Mol. Phylogenet. Evol., 33: 16-21.CrossRef | PubMed |
Liu, Y.P., G.S. Wu, Y.G. Yao, Y.W. Miao and G. Luikart et al
Multiple maternal origins of chickens: Out of the Asian jungles. Mol. Phylogenet. Evol., 38: 12-19.CrossRef | PubMed | Direct Link |
Liu, Y.P., Q. Zhu and Y.G. Yao, 2006.
Genetic relationship of Chinese and Japanese gamecocks revealed by mtDNA sequence variation. Biochem. Genet., 44: 19-29.PubMed |
Liu, Z.G., C.Z. Lei, J. Luo, C. Ding and G. H. Chen et al
Genetic variability of mtDNA sequences in Chinese native chicken breeds. Asian-Aust. J. Anim. Sci., 7: 903-909.Direct Link |
Nei, M., 1987.
Molecular Evolutionary Genetics. 1st Edn., Columbia University Press, New York, USA
Niu, D., Y. Fu, J. Luo, H. Ruan, X.P. Yu, G. Chen and Y.P. Zhang, 2002.
The origin and genetic diversity of chinese native chicken breeds. Biochem. Genet., 40: 163-174.CrossRef | PubMed | Direct Link |
Pritchard, J.K., M. Stephens and P. Donnelly, 2000.
Inference of population structure using multilocus genotype data. Genetics, 155: 945-959.PubMed | Direct Link |
Raymond, M. and F. Rousset, 1995.
An exact test for population differentiation. Evolution, 49: 1280-1283.Direct Link |
Rozas, J., J.C. Sanchez-DelBarrio, X. Messeguer and R. Rozas, 2003.
DnaSP, DNA polymorphism analyses by the coalescent and other methods. Bioinformatics, 19: 2496-2497.CrossRef | Direct Link |
Song, C.H., 2006.
The maternal origins and genetics diversity of six indigenous chicken breeds in China. M.Sc. Thesis, Shandong Agricultural University, China.
Tamura, K., J. Dudley, M. Nei and S. Kumar, 2007.
MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0. Mol. Biol. Evol., 24: 1596-1599.CrossRef | PubMed | Direct Link |
Weir, B.S. and C.C. Cockerham, 1984.
-statistics for the analysis of population structure. Evolution, 38: 1358-1370.CrossRef | Direct Link |
West, B. and B.X. Zhou, 1989.
Did chickens go North New evidence for domestication. Worlds Poult. Sci. J., 45: 205-218.CrossRef | Direct Link |
Wu, D.C., 1983.
The history of fighting cocks domestication in China (second report). J. Henan. Univ. Sci. Technol., 2: 49-63.
Xie, C., 1980.
The gamecock. Nature, 4: 28-29.
Xie, C., 1992.
The gamecocks descended from ancient China. Agric. Arch., 3: 271-274.
Zeuner, F.E., 1963.
A History of Domesticated Animals. Harper and Row, New York, pp: 443–455
Zhu, Z.Y., 1999.
The cockfight pictures around 45-23 B.C. excavated in Shiyang. Chengdu. Agric. Arch., 1: 303-305.
Qu, L.J., X.Y. Li and N. Yang, 2009.
Genetic relationships among different breeds of chinese gamecocks revealed by mtDNA variation. Asian-Aust. J. Anim. Sci., 8: 1085-1090.Direct Link |
Qu, L.J., 2004.
Studies on molecular genetic diversity of chinese local chicken breeds. Ph.D. Thesis, Chinese Agricultural University, China.
Crawford, R.D., 1990.
OriginOrigin and History of Poultry Species Poultry Genetic Resources: Evolution, Diversity and Conservation. In: Poultry Breeding and Genetics, Crawford, R.D. (Ed.). Elsevier Publishing Co., Amsterdam, The Netherlands, pp: 1-59