Vegetation Composition and Structure of Some NeotropicaMountain Grasslands in Brazil

The description and understanding of plant communities is fundamental for the implementation of conservation or restoration programs, especially when these communities are highly threatened and need to be restored.Campos rupestres, some Neotropical mountain grasslands located in central Brazil and part of the Cerrado biome(covering 2 million km2) host unique plant communities, currently threatened by quarrying and mining.The grassy matrix of campos rupestres, has long been considered a rich mosaic under the control of local topography and the nature of substrate, but this affirmation has not been well studied.We analyzed whether plant communities varied in relation to edaphic factors within the stony substrate and the sandy substrate of this grassy matrix.We selected 5 sites where occur both grasslands on stony substrate and on sandy substrate, and we carried out vegetation surveys and soil analyses.We counted 222 plant species within our communities, among which38.6% are exclusively found on campos rupestres.Our results show that both soil-types are strongly acidic, nutrient poor and exhibit a seasonal variation.Phosphorus increases and p H and organic carbon decrease during the dry season.Stony soils areslightly richer in nutrients than sandy soils and differences in soil granulometry and composition have led to the formation of distinct plant communities.Some species are confined to either one or the other grassland-type, which makes the plant composition of each community unique.Variations in edaphic factors generate heterogeneous grasslands favorable to a high plant diversity.Conservation programs and restoration actions have to maintain or recreate this heterogeneity.The presence of distinct plant communities implies that different strategies might be adopted to improve the restoration of these ecosystems.

黑色素羽毛装饰反映了鸟类的抗氧化和免疫能力吗?(英文)

鸟类信号系统研究认为,不同于类胡萝卜素,基于黑色素的羽色装饰不需要昂贵的生理代价。然而,羽毛色素细胞的黑色素沉积与抗氧化能力和免疫系统有很强的联系,而抗氧化能力和免疫系统在提高有机体适合度方面具有重要的功能。黑色素细胞的生长对氧化环境压力十分敏感;并且,黑色素本身似乎就具有抗氧化剂的功能。相应地,把抗氧化剂用于以黑色素为基础羽色发育,还是用于其它方面例如免疫调节和免疫刺激等,个体也许必须对此做出权衡。组织中的抗氧化功能大多与代谢活动有关,也就是和自由基的最高水平有关。此外,人们发现,在哺乳动物中调节黑色素沉积的激素,即α黑素细胞刺激素,在鸟类上皮组织的色素沉积中也具有同样的功能。这种进化保守的激素是免疫和炎症反应的一个重要介体。它下调前炎性细胞因子、免疫介导细胞因子和协同刺激分子,以及主要组织相容性复合体Ⅰ类分子在单核细胞的表达以及抗体的产生,而上调抑制因子白介素。黑色素在羽毛上的大量沉积,也可能反映出免疫系统在局部免疫应答的负调控能力。这些将黑色素沉积和抗氧化剂以及免疫功能联系起来的机制,表明基于黑色素的羽色信号具有一定的生理代价。

The domestication of Cucurbita argyrosperma as revealed by the genome of its wild relative

Despite their economic importance and well-characterized domestication syndrome,the genomic impact of domestication and the identification of variants underlying the domestication traits in Cucurbita species(pumpkins and squashes)is currently lacking.Cucurbita argyrosperma,also known as cushaw pumpkin or silver-seed gourd,is a Mexican crop consumed primarily for its seeds rather than fruit flesh.This makes it a good model to study Cucurbita domestication,as seeds were an essential component of early Mesoamerican diet and likely the first targets of human-guided selection in pumpkins and squashes.We obtained population-level data using tunable Genotype by Sequencing libraries for 192 individuals of the wild and domesticated subspecies of C.argyrosperma across Mexico.We also assembled the first high-quality wild Cucurbita genome.Comparative genomic analyses revealed several structural variants and presence/absence of genes related to domestication.Our results indicate a monophyletic origin of this domesticated crop in the lowlands of Jalisco.We found evidence of gene flow between the domesticated and wild subspecies,which likely alleviated the effects of the domestication bottleneck.We uncovered candidate domestication genes that are involved in the regulation of growth hormones,plant defense mechanisms,seed development,and germination.The presence of shared selected alleles with the closely related species Cucurbita moschata suggests domestication-related introgression between both taxa.

Relatedness dynamics and sex-biased dispersal in a seasonal cycle of corn mice from intensively managed agroecosystems

The sex-biased dispersal and kinship dynamics are important factors shaping the spatial distribution of individuals and are key parameters affecting a variety of ecological and evolutionary processes.Here,we studied the spatial distribution of related individuals within a population of corn mice Calomys musculinus in a seasonal cycle to infer dispersal patterns.The sampling was carried out from spring 2005 to winter 2006 in field borders of intensively managed agroecosystems.Genotyping data from 346 individuals with 9 microsatellites showed spatial genetic structure was weak for males,but not for females.The results indicate a complex spatial kinship dynamic of related females across all seasons.Which,contrary to our expectations,dispersal distances decrease with the increase of the population abundance.Meanwhile,male dispersal distances were greater when population abundance increased and thus the availability of active females.Males disperse greater distances to mate and sire offspring with distant females as a possible inbreeding avoidance mechanism.This study shows that C.musculinus is capable of much greater scattering distances than previously reported and that dispersal occurs fluidly and without barriers across the agroecosystem.The indirect benefit of dispersal on individual fitness could be related to relaxing the competition in the natal area and increasing the mating rate.Our study highlights the value of combining genetic relatedness,fieldwork observations,and behavioral data to estimate dispersal at a fine geographical scale.

Bigger or long-winged male common crossbills exhibit redder carotenoid-based plumage coloration

Carotenoid-based ornaments are often considered reliable(honest)individual condition signals because their expression implies physiological costs unaffordable for low-quality animals(handicap signals).Recently,it has been suggested that efficient cell respiration is mandatory for producing red ketocarotenoids from dietary yellow carotenoids.This implies that red colorations should be entirely unfalsifiable and independent of expression costs(index signals).In a precedent study,male common crossbills,Loxia curvirostra,showing a red plumage reported higher apparent survival than those showing yellowish-orange colors.The plumage redness in this species is due to ketocarotenoid accumulation in feathers.Here,we correlated the male plumage redness(a 4-level visual score:yellow,patchy,orange,and red)and the body morphology in more than 1,ooo adult crossbills captured in 3 Iberian localities to infer the mechanisms responsible for color evolution.A principal component analysis summarized morphometry of 10 variables(beak,wing,tarsus length,etc.).The overall body size(PC1)and the length of flight feathers regarding body size(Pc3)showed significant positive relationships with plumage redness.Plumage redness was barely correlated with bill shape measures,suggesting no constraint in acquiring carotenoids from pine cones.However,large body sizes or proportionally long flying feathers could help carotenoid acquisition via social competition or increased foraging ranges.Proportionally longer flight feathers might also be associated with a specific cell respiration profile that would simultaneously favor flying capacities and enzymatic transformations needed for ketocarotenoid synthesis.Such a phenotypic profile would agree with the hypothesis of ketocarotenoid-based colors acting as individual quality index signals.

一种由蜂类和鸟类传粉的鼠尾草属植物的花生物学:建立了有性阶段、花蜜动态过程和繁育系统与访花行为的联系

在对传粉综合征的认知过程中,人们已经意识到共享某类传粉媒介的植物间的花表型中存在着适应性趋同的现象。然而,虽然许多植物都表现出了与特定综合征相关的性状,但它们的访花传粉者却不止一种。这种情况可能意味着传粉媒介的变化,或者可能形成了一种可适应不同传粉媒介的稳定情况。此前在鼠尾草属Salvia stachydifolia中开展的一项研究表明,该物种的花形状可以最大限度地提升蜜蜂和蜂鸟的传粉效果。在本文中,我们研究了该物种的花生物学的另外3个方面:有性阶段、花蜜动态过程和繁育系统,并探讨了它们与传粉者行为之间的联系,以了解该物种在这3个方面上对蜜蜂和/或蜂鸟传粉的适应性变化。我们以某一温室种群为研究对象,对其在5种不同传粉方式下的繁育系统进行了刻画。为了确定有性阶段,我们分别对花开、花药开裂、花冠掉落和柱头可授性的情况进行了记录。此外,我们还对花蜜体积和浓度在一整天的动态变化进行了表征。最后,为了确定传粉者的组成和访花模式,我们开展了实地观测并记录传粉者的行为。研究结果显示,S.stachydifolia是部分雄蕊先成熟且可自交,但自由授粉植株的繁殖成功率最高,表明繁殖过程主要取决于传粉者的活动。熊蜂属Bombus opifex(一种大黄蜂)是最常见的访花者,但在清晨和黄昏时占主导地位的访花者则是红尾慧星蜂鸟(Sappho sparganura)。花蜜常见于大黄蜂授粉的情况。我们认为蜜蜂-蜂鸟混合访花的模式构成了一种不稳定的进化情形,使得S.stachydifolia成为一种理想的研究对象,用以了解传粉媒介发生变化的生态环境。

The Genome of Cucurbita argyrosperma (Silver- Seed Gourd) Reveals Faster Rates of Protein- Coding Gene and Long Noncoding RNA Turnover and Neofunctionalization within Cucurbita

Whole-genome duplications are an important source of evolutionary novelties that change the mode and tempo at which genetic elements evolve within a genome. The Cucurbita genus experienced a wholegenome duplication around 30 million years ago, although the evolutionary dynamics of the coding and noncoding genes in this genus have not yet been scrutinized. Here, we analyzed the genomes of four Cucurbita species, in eluding a newly assembled genome of Cucurbita argyrosperma, and compared the gene con tents of these species with those of five other members of the Cucurbitaceae family to assess the evolutionary dynamics of protein-coding and long intergenic noncoding RNA (lincRNA) genes after the genome duplication. We report that Cucurbita genomes have a higher protein-coding gene birth-death rate compared with the genomes of the other members of the Cucurbitaceae family. C. argyrosperma gene families associated with pollination and transmembrane transport had significantly faster evolutionary rates. lincRNA families showed high levels of gene turnover throughout the phylogeny, and 67.7% of the lincRNA families in Cucurbita showed evidence of birth from the neofunctionalization of previously existing protein-coding genes. Collectively, our results suggest that the whole-genome duplication in Cucurbita resulted in faster rates of gene family evolution through the neofunctionalization of duplicated genes.

蝴蝶中“假触角”的“假头”翅模式

在灰蝶科蝴蝶的种类很多，和后翅颜色图案的形态，加上一定的行为，表明一个假头的存在（FH）在栖息个人后结束。这是由FH有序适应逃避捕食者的视觉导向。FH的常见成分的尾巴，大概类似于天线，和典型的后翅来回沿矢状面运动（HWM）而栖显然移动尾巴的一种方式，触角的运动进行模拟。让33个人从18种灰蝶一个毛绒的食虫鸟，我们测试的两个替代假说关于HWM。第一个假设认为，当蝴蝶在近距离观察，HWM的扭曲的假头从而降低其欺骗效果的形状，因此，选择将有利于那些停止移动翅膀当捕食者是关闭的；假设二说HWM的频率增加，提高其偏当蝴蝶效应在近距离面对捕食者。我们的研究结果倾向于支持的第二个假设因为蝴蝶半开始将其后翅或增加率的影响当暴露于鸟类；然而，有相当比例的蝴蝶（30%）停止移动后的翅膀或预计从第一个假设HWM率降低。我们的观察也表明，在杰出的HWM率存在差异，论证了生产”的后翼尾生动”运动的替代方式的存在（“假天线”）在[当前生态61没有影响（4）：758-764，2015 ]。

Multiple color patches and parasites in Sceloporus occidentalis:differential relationships by sex and infection

Parasites generally have a negative influence on the color expression of their hosts.Sexual selection theory predicts resistant high-quality individuals should show intense coloration,whereas susceptible low-quality individuals would show poor coloration.However,intensely colored males of different species of Oid and New World lizards were more often infected by hemoparasites.These results suggest that high-quality males,with intense coloration,would suffer higher susceptibility to hemoparasites.This hypothesis remains poorly understood and contradicts general theories on sexual selection.We surveyed a population of Sceloporus occidentalis for parasites and found infections by the parasite genera Lankesterella and Acroeimeria.In this population,both males and females express ventral blue and yellow color patches.Lankesterella was almost exclusively infecting males.The body size of the males significantly predicted the coloration of both blue and yellow patches.Larger males showed darker (lower lightness)blue ventral patches and more saturated yellow patches that were also orange-skewed.Moreover,these males were more often infected by Lankesterella than smaller males.The intestinal parasite Acroeimeria infected both males and females.The infection by intestinal parasites of the genus Acroeimeria was the best predictor for the chroma in the blue patch of the males and for hue in the yellow patch of the females.Those males infected by Acroeimeria expressed blue patches with significantly lower chroma than the uninfected males.However,the hue of the yellow patch was not significantly different between infected and uninfected females.These results suggest a different effect of Lankesterella and Acroeimeria on the lizards.On the one hand,the intense coloration of male lizards infected by Lankesterella suggested high-quality male lizards may tolerate it.On the other hand,the low chroma of the blue coloration of the infected males suggested that this coloration could honestly express the infection by Acroeimeria.

Strategic adjustment of copulatory plug size in a nematode

Copulatory plugs(CP)are substances produced during copulation that block the genital openings of the female.In several species of Nematoda,males produce CP that are thought to impede female remating and thus sperm competition.The relatively large size of the CP in several nematodes,and its evolutionary loss in self-fertilizing populations of Caenorhabditis elegans,suggests that CP are costly to produce.If CP production is costly,the application of basic concepts of strategic ejaculation theory suggests a modulated allocation of CP in response to sperm competition risk.This hypothesis led us to predict that males perceiving a higher risk of sperm competition will produce larger CP.We tested these ideas with the entomopathogenic,gonochoristic nematode Rhabditis regina.Our first experiment provides evidence suggesting that production of CP is costly,because the size of CP is negatively affected by stressful conditions(high population density,small male adult size,and suboptimal food type).The results of our second experiment support the prediction that males adjust the size of CP to sperm competition risk:the average size of CP increased as the number of males competing for one female increased.Overall,our study supports the idea that in R.regina the production of CP is costly for males and that the size of the CP produced is influenced by sperm competition risk.

Snake-like calls in breeding tits

Hole-nesting tits belonging to the family Paridae produce a hissing display that resembles the exhalatory hiss of a snake.When a predatory animal enters the nest hole of a tit,tits often hiss vigorously,while lunging their head forward and shaking their wings and tail,until the intruder retreats.We assessed the acoustic similarity between such hiss calls from 6 species of tits,snake hisses,and tit syllables used in alarm vocalizations,as well as white noise as a control.Tit hiss calls showed a high degree of similarity with snake hisses from 3 different snake families.Tit hisses had lower similarity to syllable alarm calls,suggesting convergence of tit hisses in their spectral structure.Hiss calls would only be effective in protecting nest boxes if nest predators responded to these calls.In order to test this hypothesis,we trained individual Swinhoe’s striped squirrels,Tamiops swinhoei hainanus,a common predator of egg and nestling tits,to feed at feeders in proximity to nest boxes.We compared the aversive response of squirrels to tit’s hiss calls and white noise,presented in random order.Squirrels showed a higher degree of avoidance of feeders when hiss calls were played back than when white noise was presented.In conclusion,our study suggests that hole-nesting birds have evolved convergent snake-like hiss calls,and that predators avoid to prey on the contents of nest boxes from which snake-like hisses emerge.