首页 > 分享 > Case studies on reproductive ecology of lakeside daisy (Hymenoxys herbacea = H. acaulis var. glabra), and evolution of weeds in sunflower (Helianthus annuus).

Case studies on reproductive ecology of lakeside daisy (Hymenoxys herbacea = H. acaulis var. glabra), and evolution of weeds in sunflower (Helianthus annuus).

花匠小妙招
2024-11-12 19:23

摘要

One important issue in conservation biology is the assessment of ecological and genetic factors that may affect persistence of endangered and threatened species. Lakeside Daisy (Hymenoxys herbacea) is a self-incompatible, federally threatened species, and its only natural population in USA (Marblehead Peninsula, Ohio) has been seriously disturbed. The disturbances may have caused several genetic bottlenecks that probably affected genetic variability, including a reduction on the number of self-incompatibility alleles.; I investigated the effect of interplant distance on compatibility, seed set, and seed germination. Despite past disturbances and a presumably short distance dispersion of pollen and seeds, a lack of compatible mates does not seem to limit seed production on this species. Seed set was reduced at small scale distance presumably due to biparental inbreeding depression.; Few studies have assessed the effect of geitonogamous pollination on clonal, self-incompatible plants. I also investigated the effect of size of floral display on seed set in Lakeside Daisy. The subpopulation that I studied showed that due to efficient pollen transport by pollinators, seed production of this species was not pollen limited and was not significatively affected by deposition of geitonogamous pollination.; Another important issue in Conservation Biology is the evolution of weeds. With the advent of transgenic crops, fitness related transgenes may be transferred to weedy or wild relatives and enhance their weediness. Cultivated sunflower (Helianthus annuus) can be considered a "high risk" species because it easily crosses with wild relatives, and transgenic sunflowers with presumably fitness related traits have been developed. To my knowledge, this is the first study that investigates the effect of competition on fitness of F{dollar}sb1{dollar} weed-crop hybrids and weedy sunflowers. Differences in flower head production, flowering phenology, and seed set between F{dollar}sb1{dollar} hybrids, and weedy sunflowers decreased with competition. These results suggest hybridization will allow transfer of genes from crops to weeds.; I also compared fitness of F{dollar}sb1{dollar} hybrids, weedy, and backcross sunflowers. Backcrosses had an intermediate flower head production, seed set, and flowering phenology between F{dollar}sb1{dollar} and weedy sunflowers. Taken together, the results suggest that after hybridization backcrossing will facilitate the transfer of genes from crops to weeds.展开▼

机译：保护生物学的一个重要问题是评估可能影响濒危物种的持久性的生态和遗传因素。湖边雏菊（Hymenoxys herbacea）是一种不相容的，受到联邦威胁的物种，其在美国（俄亥俄州马布尔黑德半岛）的唯一自然种群受到严重干扰。干扰可能引起了可能影响遗传变异的几个遗传瓶颈，包括自我不相容等位基因数量的减少。我调查了种间距离对相容性，结实和种子发芽的影响。尽管过去有干扰，而且花粉和种子的传播距离很短，但缺乏相容的配偶似乎并未限制该物种的种子生产。推测是由于双亲近亲繁殖抑制，种子结实在小范围内减少。很少有研究评估异基因授粉对克隆的，自交不亲和植物的影响。我还研究了花卉展示的大小对湖畔雏菊种子座的影响。我研究的亚种群显示，由于传粉者有效的花粉运输，该物种的种子生产不受花粉的限制，并且不受基因组配子授粉沉积的显着影响。保护生物学的另一个重要问题是杂草的进化。随着转基因作物的出现，与健身相关的转基因可能会被转移至杂草或野生亲缘种并增强其杂草性。栽培向日葵（Helianthus annuus）可以被认为是“高风险”物种，因为它很容易与野生亲缘种杂交，并且已开发出具有健身相关性状的转基因向日葵。据我所知，这是第一项研究竞争对F {dollar} sb1 {dollar}杂草作物杂种和杂草向日葵适应性影响的研究。 F {dollar} sb1 {dollar}杂种与杂草向日葵的花头产量，开花物候和种子结实的差异随竞争而降低。这些结果表明杂交将使基因从农作物转移到杂草。我还比较了F {dollar} sb1 {dollar}杂种，杂草和回交向日葵的适合度。回交具有介于F {dollar} sb1 {dollar}和杂草向日葵之间的中间头花生产，结实和开花物候学。两者合计，结果表明杂交后回交将促进基因从农作物向杂草的转移。展开▼