| Population characteristics of growth,age structure,gonadal development,population fecundity,sex ratio of mudskipper,Boleophthalmus pectinirostris(n=317)and Periophthalmus modestus(n=361)were comparatively analysised in the eastern seaside of Leizhou Peninsula(Donghai Island,DH and Fucheng town,FC),western seaside(Xialiu town,XL and Gaoqiao town,GQ)during 2016.The genetic diversity and population genetic structure of mduskippers were investigated based on mitochondrial DN A(Cox1 gene,D-loop sequence).The results were as follows:1 The zero-years-old group of B.pectinirostris reached the maximum proportion of 44.16%,the average age of 0.5072 years in western seaside was lower than that of 1.4219 years of the eastern seaside,becoming younger.The absolute fecundity of 10 916 eggs in eastern seaside was higher than that of 3 286 eggs in the western seaside,there were no significant difference of fullness coefficient and diameter of egg between the two sides in Leizhou Peninsula.This research showed its the disposable spawning type,the length at first maturity of female was 74 mm and breeding season extended from April to June.Sex ratio was biased toward females(1.2F:1M),showed r-type selection to adapt to the huge overfishing pressure and environmental damage2 Two species of mudskipper from different ecological niches,the number of huge population of P.modestus was mainly composed of zero-year-old and one-year-old.The absolute fecundity of 2 128 eggs in eastern seaside was lower than that of 3 252 eggs in the western seaside,there were no significant difference of fullness coefficient and diameter of egg between the two sides in Leizhou Peninsula.The fecundity and the diameter egg of P.modestus were lower than those of B.pectinirostris,but its population structure and population abundance are significantly higher than those of B.pectinirostris.This research showed P.modestus was the multi-batch spawning type,Sex ratio was significantly biased toward females(2F:1M),alse showed r-type selection to cope with the fragile habitat and predation pressure from other creatures.3 The population genetic structure was an important manifestation of genetic diversity,which can reveal the genetic variation and evolution and understand the relationship between population fecundity and habitat.The sequence length polymorphism were found with the insertion and deletion of 130 bp in whole D-loop sequences.High genetic diversity(Hd=0.979~1.000,?=0.00998~0.01299)in the total populations among different geographic populations was detected.The gene flow was frequent(Nm>4),small difference of the index Snn,and the F ST(0~0.05),which was consistent with cluster analysis and minimum network of haplotype among each population.Threre exists the population experienced expansion by the distribution of nucleotide pairing,in the late Quaternary period dating back to about 0.102 to 0.026 million years ago,showed that B.pectinirostris expanded the population of floating larvae to maintain the genetic structure and number of population to adapt to huge overfishing pressure.4 In order to reveal the genetic characteristics of P.modestus,P.modestus and P.magnuspinnatus from Periophthalmus were comparatively analysis.High genetic diversity(Hd=0.9999,?=0.0.2032)was detected in P.modestus and higher haplotype diversity of 0.978 and low nucleotide diversity of 0.00707 was detected in P.magnuspinnatus.There were high gene flow(N m>4)of P.modestus between the two sides in Leizhou Peninsula,and low gene flow(N m<1)and there exists a certain genetic differentiation of P.magnuspinnatus.P.modestus had experienced mass expansion in the late Quaternary period dating back to about 0.205 to 0.018 million years ago,which showed different niche have different genetic attributes to adapt to different habitat. |
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