Life History Variation and the Coexistence of a Daphnia Hybrid With Its Parental Species
Life History Variation and the Coexistence of a Daphnia Hybrid With Its Parental Species
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杂种水蚤及其亲本的生活史变异与共存
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
J. Hoekstra
中科院分区：
文献类型：
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作者：
P. Spaak;J. Hoekstra
研究了长刺水蚤组中两种水蚤的生活史变异和基因型组成：相对较大的长刺水蚤; galeata（1.4mm），而D.僧帽状（0.9 mm）。将这些种的多位点基因型与其种间杂种D. cucullata X D.盔状花序。这两个物种和杂交共同发生在浅富营养化Tjeukemeer。连续两年在三个温度（12.5 ℃，十七点五？和22.5eC）和两个食物水平（碳浓度0.62和1.64 pg/mL）来研究允许类群在该水蚤杂交种复合体中共存的机制。三因素方差分析显示了显著的主效应（例如，温度，食物水平，分类）的大多数生殖性状（例如，新生儿的数量，年龄在第一次繁殖，幼龄的数量，内在增长率）之间的水蚤类群。对于与大小相关的性状（例如，成熟时的大小和后代的大小），只有一个主要的影响，分类，被发现。杂种是中间的亲本物种在成熟时的大小，后代的大小，和新生儿的数量。对于发育性状（幼虫龄期和成熟时的年龄）的杂交种往往有最低的值为所有条件。杂种的内禀增长率（r）与D. galeata，但显著高于D.僧帽形。我们认为，本质上r将达到更高的值的杂交比D。galeata，因为大小选择性鱼类捕食的强烈影响。我们的研究结果进行了讨论，参考不同的理论，在自然界中的杂交物种复合体的维持。
Life history variation and genotype composition were studied in two species of the Daphnia longispina group: the relatively large D. galeata (1.4 mm) and the smaller D. cucullata (0.9 mm). Several multi-locus genotypes of these species were compared with genotypes of their interspecific hybrid, D. cucullata X D. galeata. Both species and the hybrid co-occur in the shallow eutrophic Tjeukemeer. For two successive years, laboratory life table experiments were conducted at three temperatures (12.5?, 17.5?, and 22.5eC) and two food levels (carbon concentrations 0.62 and 1.64 pg/mL) to study the mechanisms that permit coexistence of taxa in this Daphnia hybrid species complex. Three-way analyses of variance showed significant main effects (e.g., temperature, food level, taxon) for most reproductive traits (e.g., number of newborns, age at first reproduction, number of juvenile instars, intrinsic rate of increase) among the Daphnia taxa. For size-related traits (e.g., size at maturity and offspring size) only one main effect, taxon, was found. Hybrids were intermediate to the parental species with respect to size at maturity, offspring size, and number of newborns. For developmental traits (number of juvenile instars and age at maturity) the hybrids tended to have the lowest values for all conditions. The intrinsic rate of increase (r) of the hybrid did not differ significantly from that of D. galeata, but was significantly higher than that of D. cucullata. We argue that essentially r will reach higher values for the hybrids than for D. galeata, because of the strong influence of size-selective fish predation. Our results are discussed in reference to different theories about the main- tenance of hybrid species complexes in nature.