The relationship between body size and stable isotopic signatures of the omnivorous Redfin Culter(C ultrichthys erythropterus),commonly found in East Lake Taihu,was investigated. Previous analyses of C. erythropterus ...The relationship between body size and stable isotopic signatures of the omnivorous Redfin Culter(C ultrichthys erythropterus),commonly found in East Lake Taihu,was investigated. Previous analyses of C. erythropterus stomach contents have shown that this species undergoes a diet switch from being predominantly zooplanktivorous to piscivorous during its life history. This was confirmed by stable carbon isotopic signature(δ 13 C) in this study,in which δ 13 C was positively correlated with both standard length and weight. The importance of littoral-benthic resources in supporting C. erythropterus during its lifespan was also demonstrated using a two-source mixing model,the results of which showed a significant increasing trend in the contribution of littoral-benthic energy. However,the stable nitrogen isotopic signature(δ 15N) exhibited an unusual pattern compared with previous studies. The δ 15 N of C. erythropterus showed no relationship with body size,even though dietary changes were observed. This indicated that δ 15 N alone cannot fully reflect a diet shift in a species and possible variability in isotopic signatures over its life history. This should be considered when using stable isotopic signatures to investigate intra-specific variations and the timing of life-history events,such as estimating the trophic positions of fish species.展开更多
Body size is a highly variable trait among geographically separated populations. Size-assortative reproductive isolation has been linked to recent adaptive radiations of threespine stickleback （Gasterosteus aculeatus...Body size is a highly variable trait among geographically separated populations. Size-assortative reproductive isolation has been linked to recent adaptive radiations of threespine stickleback （Gasterosteus aculeatus） into freshwater, but the genetic basis of the commonly found size differ- ence between anadromous and derived lacustrine sticklebacks has not been tested. We studied the genetic basis of size differences between recently diverging stickleback lineages in southwest Alaska using a common environment experiment. We crossed stickleback within one anadromous （Naknek River） and one lake （Pringle Lake） population and between the anadromous and two lake populations （Pringle and JoJo Lakes）, and raised them in a salinity of 4-6 ppt. The F1 anadromous and freshwater forms differed significantly in size, whereas hybrids were intermediate or exhibited dominance toward the anadromous form. Additionally, the size of freshwater Fls differed from their wild counterparts, with within-population Fls from Pringle Lake growing larger than their wild counterparts, while there was no size difference between lab-raised and wild anadromous fish. Sexual dimorphism was always present in anadromous fish, but not in freshwater, and not always in the hybrid crosses. These results, along with parallel changes among anadromous and fresh- water forms in other regions, suggest that this heritable trait is both plastic and may be under di- vergent and/or sexual selection.展开更多
基金Supported by the National Natural Science Foundation of China(No.41206124)the Ph.D Programs Foundation of Ministry of Education of China(No.23104120001)the "Chen Guang" Project(No.10CG52)
文摘The relationship between body size and stable isotopic signatures of the omnivorous Redfin Culter(C ultrichthys erythropterus),commonly found in East Lake Taihu,was investigated. Previous analyses of C. erythropterus stomach contents have shown that this species undergoes a diet switch from being predominantly zooplanktivorous to piscivorous during its life history. This was confirmed by stable carbon isotopic signature(δ 13 C) in this study,in which δ 13 C was positively correlated with both standard length and weight. The importance of littoral-benthic resources in supporting C. erythropterus during its lifespan was also demonstrated using a two-source mixing model,the results of which showed a significant increasing trend in the contribution of littoral-benthic energy. However,the stable nitrogen isotopic signature(δ 15N) exhibited an unusual pattern compared with previous studies. The δ 15 N of C. erythropterus showed no relationship with body size,even though dietary changes were observed. This indicated that δ 15 N alone cannot fully reflect a diet shift in a species and possible variability in isotopic signatures over its life history. This should be considered when using stable isotopic signatures to investigate intra-specific variations and the timing of life-history events,such as estimating the trophic positions of fish species.
文摘Body size is a highly variable trait among geographically separated populations. Size-assortative reproductive isolation has been linked to recent adaptive radiations of threespine stickleback （Gasterosteus aculeatus） into freshwater, but the genetic basis of the commonly found size differ- ence between anadromous and derived lacustrine sticklebacks has not been tested. We studied the genetic basis of size differences between recently diverging stickleback lineages in southwest Alaska using a common environment experiment. We crossed stickleback within one anadromous （Naknek River） and one lake （Pringle Lake） population and between the anadromous and two lake populations （Pringle and JoJo Lakes）, and raised them in a salinity of 4-6 ppt. The F1 anadromous and freshwater forms differed significantly in size, whereas hybrids were intermediate or exhibited dominance toward the anadromous form. Additionally, the size of freshwater Fls differed from their wild counterparts, with within-population Fls from Pringle Lake growing larger than their wild counterparts, while there was no size difference between lab-raised and wild anadromous fish. Sexual dimorphism was always present in anadromous fish, but not in freshwater, and not always in the hybrid crosses. These results, along with parallel changes among anadromous and fresh- water forms in other regions, suggest that this heritable trait is both plastic and may be under di- vergent and/or sexual selection.
