Evolutionary Ecology Research最新文献_第2页

Evolution of transmission mode in obligate symbionts. 强制性共生体传播方式的演变。

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2013-01-01

Devin M Drown, Peter C Zee, Yaniv Brandvain, Michael J Wade

Background: A host obtains symbionts by horizontal transmission when infected from the environment or contagiously from other hosts in the same generation. In contrast, vertical transmission occurs when a host obtains its symbionts directly from its parents. Either vertical or horizontal transmission can sustain an association between a host and its symbiont.

Questions: What evolutionary forces are necessary to evolve from an ancestral state of horizontal transmission to a derived state of vertical transmission?

Mathematical methods: We explore a general model of fitness interaction, including both additive and epistatic effects, between host and symbiont genes. Recursion equations allow us to analyse the short-term behaviour of the model and to study long-term deterministic effects with numerical iterations.

Key assumptions: Obligate interaction between a symbiont and a single host species with genetically determined horizontal and vertical transmission. No free-living symbionts or uninfected hosts and each host is infected by only a single symbiont genetic lineage (no multiple infections). No population structure.

Conclusions: Epistasis for fitness between host and symbiont genes, like that in a matching alleles model, is a necessary condition for the evolution of vertical from horizontal transmission. Stochastic individual-based simulations show that (1) mutation facilitates the switch to vertical transmission and (2) vertical transmission is a stable evolutionary endpoint for a matching alleles model.

背景：宿主通过水平传播获得共生体，即从环境中感染或从同代的其他宿主处传染。相反，当宿主直接从其父母那里获得共生体时，就会发生垂直传播。无论是垂直传播还是水平传播，都能维持宿主与其共生体之间的联系：问题：从水平传播的祖先状态进化到垂直传播的衍生状态需要哪些进化力量？我们探讨了宿主基因和共生体基因之间包括相加效应和表观效应在内的适应性相互作用的一般模型。通过递归方程，我们可以分析模型的短期行为，并通过数值迭代研究长期的确定性效应：共生体与单一宿主物种之间的强制性相互作用，其横向和纵向传播由基因决定。没有自由生存的共生体或未感染的宿主，每个宿主只受一个共生体基因系的感染（无多重感染）。没有种群结构：结论：宿主基因与共生体基因之间的适应性外显性，就像匹配等位基因模型中的外显性一样，是纵向传播与横向传播进化的必要条件。基于个体的随机模拟显示：(1)突变促进了向垂直传播的转变；(2)垂直传播是匹配等位基因模型的稳定进化终点。

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引用次数: 0

Magic cues versus magic preferences in speciation 物种形成中的魔法线索与魔法偏好

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2012-09-01 DOI: 10.7892/BORIS.16589

M. Maan, O. Seehausen

Question: How does divergent natural selection lead to divergence in mating traits and the evolution of reproductive isolation? Background: Ecological speciation of non-allopatric taxa usually requires the evolution of an association between selective mating and the traits underlying ecological adaptation. 'Magic traits' affect both ecological fitness and assortative mating and may therefore mediate rapid evolution of reproductive isolation. Problem: When assortative mating is mediated by separate preferences and cues, as opposed to being based on trait similarity (e.g. assortment by body size or habitat), pre-mating reproductive isolation between non-allopatric populations often requires divergence in both mating preferences and mating cues. However, most proposed cases of magic trait speciation rely on observation of divergent mating cues alone, leaving the consequences for reproductive isolation uncertain. Solution: We propose that a distinction should be made between mating cues and mating preferences when documenting divergent natural selection on mating traits. We argue that immediate effects of ecological adaptation on mating preferences, through direct selection or through pleiotropy, will drive divergence in both preferences and traits much more predictably than ecological selection on mating cues. The distinction between 'magic cues' and 'magic preferences' is critical for evaluating the evolutionary consequences of divergent selection on mating traits, and implies a need for increased research effort into documenting variation in mating preferences in diverging taxa.

问题:不同的自然选择是如何导致交配特征的分化和生殖隔离的进化的?背景:非异域分类群的生态物种形成通常需要选择性交配和潜在生态适应性状之间的关联进化。“神奇性状”影响生态适应性和选择性交配，因此可能介导生殖隔离的快速进化。问题:当分类交配是由单独的偏好和线索介导的，而不是基于特征相似性(例如，体型或栖息地的分类)，非异域种群之间的预交配生殖隔离通常需要交配偏好和交配线索的差异。然而，大多数提出的神奇特征物种形成的案例仅依赖于对不同交配线索的观察，这使得生殖隔离的后果不确定。解决方案:我们建议在记录交配特征的不同自然选择时，应该区分交配线索和交配偏好。我们认为，通过直接选择或多效性，生态适应对交配偏好的直接影响将比对交配线索的生态选择更可预测地推动偏好和性状的分化。“神奇线索”和“神奇偏好”之间的区别对于评估交配特征的不同选择的进化结果至关重要，这意味着需要加大研究力度，以记录不同分类群中交配偏好的变化。

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引用次数: 16

Distributions of reproductive and somatic cell numbers in diverse Volvox (Chlorophyta) species. 不同绿藻种的生殖和体细胞数量分布。

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2012-01-01

Deborah E Shelton, Alexey G Desnitskiy, Richard E Michod

Background: Volvox (Chlorophyta) asexual colonies consist of two kinds of cells: a large number of small somatic cells and a few large reproductive cells. The numbers of reproductive and somatic cells correspond directly to the major components of fitness - fecundity and viability, respectively. Volvox species display diverse patterns of development that give rise to the two cell types.

Questions: For Volvox species under fixed conditions, do species differ with respect to the distribution of somatic and reproductive cell numbers in a population of asexual clones? Specifically, do they differ with respect to the dispersion of the distribution, i.e. with respect to their intrinsic variability? If so, are these differences related to major among-species developmental differences?

Data description: For each of five Volvox species, we estimate the number of somatic and reproductive cells for 40 colonies and the number of reproductive cells for an additional 200 colonies. We sampled all colonies from growing, low-density, asexual populations under standard conditions.

Search method: We compare the distribution of reproductive cell numbers to a Poisson distribution. We also compare the overall dispersion of reproductive cell number among species by calculating the coefficient of variation (CV). We compare the bivariate (reproductive and somatic cell) dataset to simulated datasets produced from a simple model of cell-type specification with intrinsic variability and colony size variation. This allows us to roughly estimate the level of intrinsic variability that is most consistent with our observed bivariate data (given an unknown level of size variation).

Conclusions: The overall variability (CV) in reproductive cell number is high in Volvox compared with more complex organisms. Volvox species show differences in reproductive cell number CV that were not clearly related to development, as currently understood. If we used the bivariate data and tried to account for the effects of colony size variation, we found that the species that have fast embryonic divisions and asymmetric divisions have substantially higher intrinsic variability than the species that have slow divisions and no asymmetric divisions. Under our culture conditions, the Poisson distribution is a good description of intrinsic variability in reproductive cell number for some but not all Volvox species.

背景:绿藻(Volvox(吊藻))无性菌落由两种细胞组成:大量的小体细胞和少量的大生殖细胞。生殖细胞和体细胞的数量分别直接对应于适合度的主要组成部分——繁殖力和生存力。团藻种类显示出不同的发育模式，从而产生两种细胞类型。问题:对于固定条件下的团藻物种，在无性克隆群体中，物种在体细胞和生殖细胞数量的分布方面是否有所不同?具体来说，它们在分布的离散度方面是否不同，即它们的内在可变性方面是否不同?如果是这样，这些差异是否与物种间的主要发育差异有关?数据描述:我们估计了5种涡旋菌中每一种有40个菌落的体细胞和生殖细胞数量，以及另外200个菌落的生殖细胞数量。我们在标准条件下从生长的低密度无性种群中取样所有菌落。检索方法:我们将生殖细胞数目的分布与泊松分布进行比较。我们还通过计算变异系数(CV)比较了生殖细胞数量在物种间的总体分布。我们将双变量(生殖细胞和体细胞)数据集与由具有内在变异性和菌落大小变化的细胞类型规格的简单模型产生的模拟数据集进行比较。这使我们能够粗略地估计与我们观察到的双变量数据最一致的内在变异性水平(给定未知的大小变化水平)。结论:与更复杂的生物相比，团藻生殖细胞数量的总体变异性(CV)较高。涡旋属植物在生殖细胞数量CV上存在差异，但与发育的关系尚不明确。如果我们使用双变量数据并试图解释群体大小变化的影响，我们发现具有快速胚胎分裂和不对称分裂的物种比具有缓慢分裂和不对称分裂的物种具有更高的内在变异性。在我们的培养条件下，泊松分布很好地描述了一些但不是所有涡藻物种生殖细胞数量的内在变异性。

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引用次数: 0

Does water depth or diet divergence predict progress towards ecological speciation in whitefish radiations 水深或饮食差异是否能预测白鱼辐射中生态物种形成的进展

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2012-01-01 DOI: 10.7892/BORIS.16333

T. Ingram, A. G. Hudson, P. Vonlanthen, O. Seehausen

Question: Is the extent of genetic divergence between sympatric whitefish ecotypes – a proxy for progress towards speciation – related to the extent of ecological divergence in spawning depth or diet? Study system: Whitefish (Coregonus spp.) that have diversified into two or more sympatric ecotypes in subalpine Swiss lakes. Sympatric ecotypes vary in the extent of reproductive isolation. Analytical methods: We measured the degree of spawning depth differentiation based on the depth-at-capture of different ecotypes. We estimated diet differentiation between ecotypes as Mahalanobis distances from stable isotopes. We compared each of these to genetic differentiation measured from AFLP data, using modified correlation tests and phylogenetically independent contrasts to account for non-independence of comparisons in lakes with more than two ecotypes. Results: We found that the magnitude of divergence in spawning depth was generally – albeit only marginally significantly – associated with the extent of genetic divergence between sympatric ecotypes. This effect was clearly stronger than the effect of diet divergence, which was not associated with genetic differentiation. Furthermore, there was no evidence for an interactive effect of depth and diet divergence on progress towards speciation.

问题:同域白鱼生态型之间的遗传差异程度——物种形成进程的代表——与产卵深度或饮食的生态差异程度有关吗?研究系统:瑞士亚高山湖泊中已分化为两种或两种以上同域生态型的白鱼(Coregonus spp.)。同域生态型的生殖隔离程度各不相同。分析方法:根据不同生态型的捕获深度来衡量产卵深度分化程度。我们估计生态型之间的饮食差异是马氏鱼与稳定同位素的距离。我们将这些数据与从AFLP数据中测量的遗传分化进行了比较，使用改进的相关测试和系统发育独立的对比来解释具有两个以上生态型的湖泊中比较的非独立性。结果:我们发现产卵深度的差异程度通常与同域生态类型之间的遗传差异程度相关，尽管只是略微显着。这种影响明显强于饮食差异的影响，而饮食差异与遗传分化无关。此外，没有证据表明深度和饮食差异对物种形成进程有相互作用。

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引用次数: 14

Effect of competition on niche dynamics of syntopic grazing ungulates: contrasting the predictions of habitat selection models using stable isotope analysis 竞争对合栖放牧有蹄类生态位动态的影响:利用稳定同位素分析对比生境选择模型的预测

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2011-01-01 DOI: 10.5167/UZH-49216

D. Codron, J. Hull, J. Brink, J. Codron, D. Ward, M. Clauss

Background: Theories of density-dependent habitat selection provide two solutions for co-existence of competing species. The niche compression hypothesis predicts that species reduce their respective niche breadths in response to inter-specific competition. Alternatively, if the species have similar resource preferences, the subordinate species may be forced to expand its niche to incorporate secondary resources. Aim: Determine whether grazing ungulate species partition the resource by compression or expansion of dietary niches. Organisms: Black wildebeest (Connochaetes gnou) and blue wildebeest (C. taurinus). Methods: Stable carbon and nitrogen isotope analysis of faeces. Isotopic niche breadths are compared across allopatric and sympatric wildebeest populations in South African grasslands. Results: Stable carbon and nitrogen isotope niche breadths of the two wildebeest species were virtually identical. In sympatry, however, black wildebeest had a narrower δ13C niche breadth (indicating almost exclusive use of C4 grass), whereas blue wildebeest had a wider δ13C niche breadth (indicating significant contributions from C3 sources). Blue wildebeest also had a wider δ15N niche breadth than sympatric black wildebeest. Moreover, the δ13C niche breadths of sympatric black wildebeest and blue wildebeest were narrower and wider, respectively, than those of allopatric populations of either species. Conclusions: Isotope niche dynamics across allopatric and sympatric populations arise due to the combined effects of competition and habitat heterogeneity on resource use. Although results for black wildebeest resemble niche compression, this hypothesis cannot explain patterns observed in blue wildebeest. Expansion of the blue wildebeest niche, and restricted niche breadth of black wildebeest, is consistent with predictions of a shared preference model in which black wildebeest are the dominant competitor. When competition is operating, differences in the way species use secondary resources can have an important role in structuring grazer assemblages.

背景:密度依赖的生境选择理论为竞争物种的共存提供了两种解决方案。生态位压缩假说预测物种为了应对种间竞争而减少各自的生态位宽度。或者，如果物种有相似的资源偏好，从属物种可能会被迫扩大其生态位以吸收次要资源。目的:确定放牧有蹄类动物是否通过压缩或扩大饮食生态位来分配资源。生物:黑角马(Connochaetes gnou)和蓝角马(C. taurinus)。方法:对粪便进行稳定碳、氮同位素分析。同位素生态位宽度在南非草原的异域和同域角马种群之间进行了比较。结果:两种角马的稳定碳和氮同位素生态位宽度几乎相同。然而，在同属植物中，黑角马的δ13C生态位宽度较窄(表明几乎完全利用C4草)，而蓝角马的δ13C生态位宽度较宽(表明C3源的贡献很大)。蓝角马的δ15N生态位宽度也比同域黑角马大。同域黑角马和蓝角马的δ13C生态位宽度分别比同域黑角马和蓝角马的δ13C生态位宽度窄和宽。结论:异域和同域种群的同位素生态位动态是由竞争和生境异质性对资源利用的综合影响引起的。虽然黑角马的结果类似于生态位压缩，但这一假设不能解释在蓝角马中观察到的模式。蓝角马生态位的扩大和黑角马生态位宽度的限制与共同偏好模型的预测一致，其中黑角马是主要的竞争对手。当竞争发生时，物种利用次生资源的方式的差异可能在构建食草动物组合中发挥重要作用。

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引用次数: 25

Impacts of starvation on male reproductive success in Tribolium castaneum 饥饿对木栗雄性繁殖成功的影响

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2011-01-01 DOI: 10.3929/ETHZ-A-009988013

S. Sbilordo, Vera M. Grazer, Marco Demont, O. Martin

Background: Starvation is known to decrease male reproductive success in Tribolium castaneum. Starved males transfer less sperm, but we do not know whether reduced reproductive success is caused by lower oviposition rates of females or more frequent deposition of unfertilized eggs. Study organism: The red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae). Questions: Does the nutritional state of a male influence female oviposition rate and/or fertilization capability? Does sperm use by females at fertilization reflect reduced numbers of sperm transferred by starved males? Hypothesis: If the number of sperm released by females reflects the number of sperm stored, we would expect the number of sperm per egg to be inferior if mated with starved males. Methods: We assessed female oviposition rate and fertilization capability in females mated with fed versus starved males. We also quantified sperm use via microscopical counts of DAPI-stained sperm heads on freshly deposited eggs. Results: Females mated with starved males were less likely to deposit eggs and deposited fewer eggs. Furthermore, the eggs of females mated with starved males had fewer sperm, and those females laid a significantly higher proportion of unfertilized eggs. Based on our counts of sperm per egg, we estimate that for starved males, about a third less sperm come close to the site of fertilization.

背景:饥饿是已知的减少雄性繁殖成功的三角狼。饥饿的雄性转移的精子较少，但我们不知道繁殖成功率降低是由于雌性产卵率较低还是未受精卵更频繁地沉积造成的。研究生物:赤粉甲虫(鞘翅目:拟甲科)。问题:雄性的营养状况是否会影响雌性的产卵率和/或受精能力?受精时雌性精子的使用是否反映了饥饿的雄性精子移植数量的减少?假设:如果雌性释放的精子数量反映了储存的精子数量，我们可以预期，如果与饥饿的雄性交配，每个卵子的精子数量会更低。方法:我们评估了雌性与喂食和饥饿雄性交配的产卵率和受精率。我们还通过在新鲜卵子上对dapi染色的精子头进行显微镜计数来定量精子的使用。结果:雌性与饥饿的雄性交配产卵的可能性更小，产卵量也更少。此外，与饥饿雄鱼交配的雌鱼的卵子精子数量较少，而这些雌鱼产卵的未受精卵比例显著高于饥饿雄鱼。根据每个卵子的精子数量，我们估计，对于饥饿的雄性来说，接近受精地点的精子大约少了三分之一。

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引用次数: 26

Methane production in relation to body mass of ruminants and equids 反刍动物和马科动物体重与甲烷产量的关系

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2010-01-01 DOI: 10.5167/UZH-41217

R. Franz, C. Soliva, M. Kreuzer, P. Steuer, J. Hummel, M. Clauss

Background: Mammalian herbivores produce methane during digestion. Questions: Do ruminants (such as bovids) produce more methane during digestion than do equids (non-ruminants)? What are the effects of allometric scaling of methane production when different species feed on similar diets? Methods: From the literature, we collected a set of data on methane production (litres ·day−1) of ruminants (body mass 26–610 kg) and equids (208–850 kg) fed only roughage. To these data we added our own experimental results from three sheep (Ovis orientalis aries, 94 ± 4 kg) and three mini Shetland ponies (Equus ferus caballus, 97 ± 6 kg). We gave these six animals ad libitum access to the same batch of grass hay. We measured their food intake and methane production (using respiratory chambers), and calculated gut fill and food digestibility. Results: Daily dry matter intake and dry matter digestibility were 39 ± 10 g ·kg−0.75 day−1 and 48 ± 2% in sheep and 72 ± 16 g ·kg−0.75 day−1 and 41 ± 3% in ponies, respectively; the calculated dry matter gut fill was 2.0 ± 0.5% of body mass in sheep and 1.9 ± 0.4% in ponies. Methane production was higher in sheep (30.3 ± 3.0 litres ·day−1) than in ponies (13.4 ± 4.6 litres ·day−1), representing 6.7 ± 1.7% and 1.5 ± 0.2% of gross energy intake, respectively. The data set revealed a linear increase of methane production with body mass (i.e. M1.0) in equids and ruminants. However, a ruminant produces 3.6 times as much methane as does an equid of comparable body mass. Conclusions: Because energy and food intake scale allometrically with body mass (M0.75), our results mean that energetic losses due to methane production (as a proportion of overall energy intake) increase with increasing body mass. The magnitude of the losses is enough to limit the maximum size of a ruminant’s body, but not that of an equid.

背景:食草哺乳动物在消化过程中产生甲烷。反刍动物(如牛科动物)在消化过程中产生的甲烷比马科动物(非反刍动物)多吗?当不同物种以相似的食物为食时，甲烷产量异速缩放的影响是什么?方法:从文献中收集了一组仅饲喂粗饲料的反刍动物(体重26-610 kg)和马科动物(208-850 kg)的甲烷产量(升·天−1)数据。在这些数据中，我们还加入了我们自己的实验结果，实验对象是3只羊(东方羊，94±4千克)和3匹迷你设得兰矮种马(马科，97±6千克)。我们让这六只动物随意使用同一批干草。我们测量了它们的食物摄入量和甲烷产量(使用呼吸室)，并计算了肠道填充率和食物消化率。结果:绵羊日干物质采食量和干物质消化率分别为39±10 g·kg−0.75 day - 1和48±2%，小马日干物质消化率分别为72±16 g·kg−0.75 day - 1和41±3%;绵羊和小马的干物质肠填充率分别为体重的2.0±0.5%和1.9±0.4%。绵羊的甲烷产量(30.3±3.0 l·day - 1)高于小马(13.4±4.6 l·day - 1)，分别占总能量摄入的6.7±1.7%和1.5±0.2%。该数据集显示，马科动物和反刍动物的甲烷产量随体重(即M1.0)呈线性增加。然而，反刍动物产生的甲烷是同等体重的马的3.6倍。结论:由于能量和食物摄入与体重呈异速增长(M0.75)，我们的研究结果表明，由于甲烷产生的能量损失(占总能量摄入的比例)随着体重的增加而增加。损失的幅度足以限制反刍动物身体的最大尺寸，但对马科动物来说却不够。

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引用次数: 42

Ploidy composition in all-hybrid frog populations in relation to ecological conditions 全杂交蛙种群倍性组成与生态条件的关系

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2010-01-01 DOI: 10.5167/UZH-38402

C. Jakob, Martina Arioli, H. Reyer

Question: What explains the differences in ratios of diploid (LR) and two types of triploid frogs (LLR, LRR) among all-hybrid frog populations? Hypothesis: Ecological conditions favouring one (LL) or the other (RR) parental species also favour those triploids that carry two copies of the respective genome (dosage effect), whereas diploids dominate under intermediate conditions. Organism: European water frog (Pelophylax esculentus). Field site: Thirty-four natural ponds in the province of Skane, southern Sweden. Methods: We caught more than 3000 frogs, determined their genotypes with microsatellites, and related the ploidy composition to several uncorrelated ecological parameters, including pond morphology, vegetation, and physical and chemical water parameters. Conclusions: We found a shift from predominantly LLR in small isolated ponds to more LRR in large wetland ponds. This parallels the preferences of the parental species LL and RR for small and large bodies of water, respectively. The effects that pond vegetation and physico-chemical water parameters exert on the parental species were not found in all-hybrid populations. This suggests that environmental parameters affect the genotype composition of all-hybrid populations less than populations containing the parental species. Pond-to-pond differences in LR, LLR, and LRR proportions seem to be better explained by differences in gamete production and thus inheritance patterns.

问题:如何解释全杂交蛙种群中二倍体(LR)和两种三倍体蛙(LLR、LRR)的比例差异?假设:有利于一个亲本物种(LL)或另一个亲本物种(RR)的生态条件也有利于携带各自基因组两个拷贝的三倍体(剂量效应)，而二倍体在中间条件下占主导地位。生物:欧洲水蛙(Pelophylax esculentus)研究地点:瑞典南部斯科讷省34个天然池塘。方法:捕获青蛙3000余只，利用微卫星测定其基因型，并将倍性组成与池塘形态、植被、水体理化参数等不相关的生态参数进行关联。结论:从小型孤立池塘的LRR为主向大型湿地池塘的LRR为主转变。这与亲本物种LL和RR分别对小水体和大水体的偏好相似。池塘植被和水体理化参数对亲本种的影响在全杂交群体中没有发现。这表明环境参数对全杂交群体基因型组成的影响小于含有亲本种的群体。塘与塘之间LR、LLR和LRR比例的差异似乎可以用配子产量的差异和遗传模式的差异来更好地解释。

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引用次数: 15

Size-dependent energetics of metamorphosis in the yellow dung fly, Scathophaga stercoraria 黄粪蝇变态的大小依赖能量学

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2009-01-01 DOI: 10.5167/UZH-30455

C. Reim, C. Kaufmann, W. Blanckenhorn

Competing hypotheses: (1) Large body size confers more efficient energy use (relative efficiency hypothesis). (2) Large body size requires more energy to be sustained, a disadvantage when food is limited (absolute energy demand hypothesis). Organism: Yellow dung flies, Scathophaga stercoraria (Diptera: Scathophagidae), artificially selected for large and small body size in the laboratory for 24 generations to augment the available phenotypic body sizes. Methods: Larvae were reared under limited and unlimited food (dung) conditions, and the energy content of pupae was measured at the beginning and the end of the pupal stage in different, size-matched individuals. Conclusions: Over the pupal period, lipids and glycogen decreased whereas sugar content increased. Net energy loss per unit body mass was higher at unlimited food. Contrary to expectation, males (the larger sex) lost less energy than females. Large selection line pupae showed the highest absolute and mass-specific energy loss during metamorphosis, indicating a correlated physiological response to body size selection because phenotypic body sizes do not differ between the lines at limited dung. We conclude that energetic costs due to greater absolute energy demand of larger individuals during the pupal phase outweigh the benefits due to greater metabolic efficiency.

相互竞争的假说:(1)体型越大，能量利用效率越高(相对效率假说)。(2)体型大需要更多的能量来维持，在食物有限的情况下(绝对能量需求假说)是一个劣势。生物:黄粪蝇，粪蝇科(双翅目:粪蝇科)，在实验室人工选择大小体型24代，以增加可用的表型体型。方法:分别在有限和无限食物(粪)条件下饲养幼虫，测定不同个体蛹期开始和结束时蛹的能量含量。结论:在蛹期，脂质和糖原降低，糖含量增加。在不限量食物的情况下，单位体重的净能量损失更高。与预期相反，雄性(较大的性别)比雌性损失的能量少。大选择系的蛹在变态过程中表现出最高的绝对能量损失和质量比能量损失，这表明了与体型选择相关的生理反应，因为在有限的粪便中，表型体型在不同的系之间没有差异。我们得出的结论是，在蛹期，体型较大的个体因绝对能量需求增加而产生的能量成本超过了代谢效率提高所带来的收益。

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引用次数: 8

The genetic correlation between flower size and water use efficiency in monkeyflowers. 猴花花大小与水分利用效率的遗传相关性。

Q2 Agricultural and Biological Sciences

Evolutionary Ecology Research

Pub Date : 2008-01-01

John K Kelly, Liza M Holeski, H S Arathi

QUESTION: Does water loss during drought stress represent an important physiological constraint on the evolution of flower size? ORGANISM: A genetically diverse population of Mimulus guttatus (yellow monkeyflower) originally sampled from an alpine meadow in Oregon, USA. METHODS: We grew plants of three different genotypic classes (small, medium, and large flowered) under both well-watered and drought-stress conditions and measured water use efficiency using stable carbon isotopes. RESULTS: There was no difference in water use efficiency among flower size genotypes under well-watered conditions, but the water use efficiency of small-flowered plants was substantially lower than that of medium or large genotypes under drought stress. Whether this paradoxical result is a direct effect of flower size or an indirect (i.e. pleiotropic) effect, the presence of a genetic correlation between floral and physiological traits indicates that selection of one does impact the other.

问：干旱胁迫下的水分流失是否代表了花大小进化的重要生理限制？生物：黄猴花（Mimulus guttatus）的遗传多样性种群，最初取样于美国俄勒冈州的高山草甸。方法：我们在水分充足和干旱胁迫条件下种植了三种不同基因型（小花、中花和大花）的植物，并使用稳定碳同位素测量了水分利用效率。结果：在水分充足的条件下，不同花大小基因型植物的水分利用效率没有差异，但在干旱胁迫下，小花型植物的水分利用效率明显低于中、大基因型植物。无论这种矛盾的结果是花大小的直接影响还是间接（即多效性）影响，花和生理性状之间存在遗传相关性表明，选择其中一个确实会影响另一个。

引用次数: 0