Investigation into the paternity of four abaca （Musa textilis L, Nee） hybrids was done to ascertain the mode of transmission of selected morpho-agronomic traits and to detect possible heterosis. In situ morphologica...Investigation into the paternity of four abaca （Musa textilis L, Nee） hybrids was done to ascertain the mode of transmission of selected morpho-agronomic traits and to detect possible heterosis. In situ morphological characterization was undertaken using twenty five qualitative and six quantitative characters. Results revealed that a great majority of the qualitative traits were shared by both parents and their hybrids. For the rest, the qualitative traits were inherited from one or the other parent though some variant phenotypes （i.e. chimerism） were also noted in the hybrids. Cases ofheterosis were also observed and this could be exploited to increase fiber yield in the hybrids. Though inconclusive due to factors such as the heterogenous nature of abaca plants in the field and the susceptibility of morphological traits to environmental fluctuations, this study has provided baseline information on abaca hybridity that can be verified using more robust technologies as molecular markers.展开更多
The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selec- tion to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between ge...The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selec- tion to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between gene flow and selection, con- cluding that speciation with gene flow was unlikely under a ＂two-allele model＂ （where two traits were necessary for reproductive isolation） but that divergence could occur quite easily under a ＂one-allele model.＂ Despite this finding, much of the sympatric speciation research involving phytophagous insects has relied on a two-trait model, where insects evolve both preferences for and increased performance on novel host plants. Philopatry （a tendency to remain where one was born） is known to occur in phyto- phagous insects and is a single trait isolation mechanism. However, it is traditionally invoked as simply augmenting reproductive isolation. Species in the Enchenopa binotata complex are believed to have speciated in sympatry. They exhibit host plant prefe- rences, host specific performance advantages and strong philopatry. We experimentally shifted E. binotata to evolutionarily novel host plants. Previous research has demonstrated that the experimental population of insects possesses genetic variation in prefe- rence and performance to the novel host. The degree of philopatry at mating and egg-laying was assayed for the first four years under full choice conditions. Host plant preference and performance was assayed after eight years. Philopatry was an immediate and strong isolating mechanism, while preference for and performance on the novel host lagged. We therefore suggest that philo- patry may be a more important mechanism in the early stages of a host shift than previously believed [Current Zoology 59 （5）： 658-666, 2013].展开更多
文摘Investigation into the paternity of four abaca （Musa textilis L, Nee） hybrids was done to ascertain the mode of transmission of selected morpho-agronomic traits and to detect possible heterosis. In situ morphological characterization was undertaken using twenty five qualitative and six quantitative characters. Results revealed that a great majority of the qualitative traits were shared by both parents and their hybrids. For the rest, the qualitative traits were inherited from one or the other parent though some variant phenotypes （i.e. chimerism） were also noted in the hybrids. Cases ofheterosis were also observed and this could be exploited to increase fiber yield in the hybrids. Though inconclusive due to factors such as the heterogenous nature of abaca plants in the field and the susceptibility of morphological traits to environmental fluctuations, this study has provided baseline information on abaca hybridity that can be verified using more robust technologies as molecular markers.
文摘The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selec- tion to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between gene flow and selection, con- cluding that speciation with gene flow was unlikely under a ＂two-allele model＂ （where two traits were necessary for reproductive isolation） but that divergence could occur quite easily under a ＂one-allele model.＂ Despite this finding, much of the sympatric speciation research involving phytophagous insects has relied on a two-trait model, where insects evolve both preferences for and increased performance on novel host plants. Philopatry （a tendency to remain where one was born） is known to occur in phyto- phagous insects and is a single trait isolation mechanism. However, it is traditionally invoked as simply augmenting reproductive isolation. Species in the Enchenopa binotata complex are believed to have speciated in sympatry. They exhibit host plant prefe- rences, host specific performance advantages and strong philopatry. We experimentally shifted E. binotata to evolutionarily novel host plants. Previous research has demonstrated that the experimental population of insects possesses genetic variation in prefe- rence and performance to the novel host. The degree of philopatry at mating and egg-laying was assayed for the first four years under full choice conditions. Host plant preference and performance was assayed after eight years. Philopatry was an immediate and strong isolating mechanism, while preference for and performance on the novel host lagged. We therefore suggest that philo- patry may be a more important mechanism in the early stages of a host shift than previously believed [Current Zoology 59 （5）： 658-666, 2013].
