Sexual size dimorphism theory predicts biased operational sex ratios(OSRs)and an uneven distribution of males among certain females.We studied this phenomenon through a field census of the giant wood spider Nephila pi...Sexual size dimorphism theory predicts biased operational sex ratios(OSRs)and an uneven distribution of males among certain females.We studied this phenomenon through a field census of the giant wood spider Nephila pilipes(family Nephilidae)in Singapore,a species where females are,on average,6.9 times larger than males.Specifically,we tested two hypotheses concerning male distribution,given their tendency to aggregate in certain female webs.The optimal female size hypothesis predicts that males would predominantly occupy webs of intermediate-sized females.The web clustering hypothesis posits that more males would be found in webs closer together compared to those farther apart.Our snapshot census revealed a female-biased OSR(females:males=1.85)with an uneven distribution of males in female webs.Most males were found in webs of intermediate-sized females aligning with the optimal female size hypothesis.Proximity among female webs was indicative of male presence,lending support to the web clustering hypothesis.While our study's limited sample size warrants caution,we conclude that in N.pilipes,male occupation of female webs is facilitated by the clustering of webs,and males prefer to cohabit with optimally sized,receptive females.展开更多
Spider dragline silk is synthesized in special gland named major ampulate (MA) gland. The MA glands were dissected from the abdomen of the spiders Nephila clavata and the total RNA was extracted by the TRIZOL. The cDN...Spider dragline silk is synthesized in special gland named major ampulate (MA) gland. The MA glands were dissected from the abdomen of the spiders Nephila clavata and the total RNA was extracted by the TRIZOL. The cDNA of dragline silk was amplificated by RT-PCR (reverse transcription polymerase chain reaction), multiplex PCR and cloned. PCR identification, restriction analysis and DNA sequence analysis were carried out to verify the recombinant plasmids. The codon usage frequencies of the cloned cDNA were added up, and the predicted amino acid sequence was compared with Spidroin2 of Nephila clavipes. Predicted secondary structure of the predicted amino-acid sequence was analysized by DNAStar software. All results showed that the cloned cDNA we got (GenBank Accession No. AF441245) was the very fragment of spider dragline silk Spidroin2 cDNA.展开更多
基金the Singapore National Parks for authorizing our research(Permit No.NP/RP20-090-2a)MatjažKuntner was supported by the Slovenian Research and Innovation Agency(grants P1-0255+2 种基金J1-9163)Singapore's Lee Kong Chian Natural History Museum Visiting Fellowship.ErikŠtrumbelj was supported by the Slovenian Research and Innovation Agency(grant P2-0442)Jana Faganeli Pucer was supported by the Slovenian Research and Innovation Agency(grant P2-0209).
文摘Sexual size dimorphism theory predicts biased operational sex ratios(OSRs)and an uneven distribution of males among certain females.We studied this phenomenon through a field census of the giant wood spider Nephila pilipes(family Nephilidae)in Singapore,a species where females are,on average,6.9 times larger than males.Specifically,we tested two hypotheses concerning male distribution,given their tendency to aggregate in certain female webs.The optimal female size hypothesis predicts that males would predominantly occupy webs of intermediate-sized females.The web clustering hypothesis posits that more males would be found in webs closer together compared to those farther apart.Our snapshot census revealed a female-biased OSR(females:males=1.85)with an uneven distribution of males in female webs.Most males were found in webs of intermediate-sized females aligning with the optimal female size hypothesis.Proximity among female webs was indicative of male presence,lending support to the web clustering hypothesis.While our study's limited sample size warrants caution,we conclude that in N.pilipes,male occupation of female webs is facilitated by the clustering of webs,and males prefer to cohabit with optimally sized,receptive females.
文摘Spider dragline silk is synthesized in special gland named major ampulate (MA) gland. The MA glands were dissected from the abdomen of the spiders Nephila clavata and the total RNA was extracted by the TRIZOL. The cDNA of dragline silk was amplificated by RT-PCR (reverse transcription polymerase chain reaction), multiplex PCR and cloned. PCR identification, restriction analysis and DNA sequence analysis were carried out to verify the recombinant plasmids. The codon usage frequencies of the cloned cDNA were added up, and the predicted amino acid sequence was compared with Spidroin2 of Nephila clavipes. Predicted secondary structure of the predicted amino-acid sequence was analysized by DNAStar software. All results showed that the cloned cDNA we got (GenBank Accession No. AF441245) was the very fragment of spider dragline silk Spidroin2 cDNA.
