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1.
Am Nat ; 195(6): 935-947, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32469655

RESUMO

The Adaptive Geometry of Trees had an important conceptual influence on plant ecology and helped inspire many new approaches to understanding succession, plant adaptation, and plant competition. Its central model provided an elegant potential explanation for how optimal canopy form should shift with ecological conditions, change those conditions through time, and thus help drive succession and be a consequence of it. Yet on close examination, this deeply inspirational model does not lead to the predictions for which it is widely known. Here I show that the Horn model actually favors monolayer canopies over multilayers under all light conditions if relative growth rate (growth per unit investment) is maximized. Horn's conclusion that multilayers would be favored over monolayers in brighter sites is an artifact. I propose that self-shading multilayers might gain an advantage in brightly lit sites by reducing water loss, reducing the costs of branch construction and maintenance, reducing photoinhibition, increasing light capture in sidelit microsites, and increasing water and nutrient supplies (or leaf longevity) when combined with one or more of the previous potential advantages. I conclude with a brief discussion connecting Horn's model to other conceptual frameworks in plant ecology and outlining possible future extensions.

2.
Am J Bot ; 106(6): 807-820, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31157408

RESUMO

PREMISE: In patterned fens, patches of short, sparse, species-rich vegetation often occur on substrates rich in precipitated carbonates near calcareous springheads, with taller, denser vegetation farther away. Boyer and Wheeler (1989) hypothesized that phosphorus co-precipitation near springheads limits plant productivity and coverage, and Givnish (1982) proposed that aggregations of rare, short-statured plant species might reflect their competitive restriction to sparsely covered microsites. METHODS: We tested these hypotheses by quantifying species distributions, leaf heights, plant coverage, community composition, and substrate and leaf chemistry of Eupatorium perfoliatum along a gradient of hydrology and geochemistry in a wetland complex in southeastern Wisconsin, USA, ranging from marl flats and fens on peat mounds near springheads to surrounding sedge meadows. RESULTS: Community composition was strongly correlated with a one-dimensional environmental gradient along which coverage and height increased moving downslope from marl flats, while soil carbonate, phosphorus immobilization capacity, and local species richness decreased, consistent with theory. Regionally rare species were short and restricted to sparsely covered microsites; within and among species, leaf height increased with local coverage. NPK tissue stoichiometry did not entirely support the Boyer-Wheeler hypothesis, although nitrogen limitation appeared strongest in sedge meadows. Shifts in stature and tissue chemistry of E. perfoliatum along the marl flat-sedge meadow gradient suggested that zinc toxicity may help limit coverage near springheads despite no significant change in soil zinc content. CONCLUSIONS: We propose a modified Boyer-Wheeler hypothesis to account for cascading effects of phosphorus co-precipitation near springheads on nitrogen fixation, nitrogen+phosphorus co-limitation, and zinc mobility.


Assuntos
Biodiversidade , Eupatorium/fisiologia , Solo/química , Áreas Alagadas , Eupatorium/crescimento & desenvolvimento , Nitrogênio/metabolismo , Fósforo/metabolismo , Dispersão Vegetal , Dinâmica Populacional , Potássio/metabolismo , Wisconsin
3.
Am J Bot ; 105(11): 1938-1950, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30408151

RESUMO

PREMISE OF THE STUDY: We used spatial phylogenetics to analyze the assembly of the Wisconsin flora, linking processes of dispersal and niche evolution to spatial patterns of floristic and phylogenetic diversity and testing whether phylogenetic niche conservatism can account for these patterns. METHODS: We used digitized records and a new molecular phylogeny for 93% of vascular plants in Wisconsin to estimate spatial variation in species richness and phylogenetic α and ß diversity in a native flora shaped mainly by postglacial dispersal and response to environmental gradients. We developed distribution models for all species and used these to infer fine-scale variation in potential diversity, phylogenetic distance, and interspecific range overlaps. We identified 11 bioregions based on floristic composition, mapped areas of neo- and paleo-endemism to establish new conservation priorities and predict how community-assembly patterns should shift with climatic change. KEY RESULTS: Spatial phylogenetic turnover most strongly reflects differences in temperature and spatial distance. For all vascular plants, assemblages shift from phylogenetically clustered to overdispersed northward, contrary to most other studies. This pattern is lost for angiosperms alone, illustrating the importance of phylogenetic scale. CONCLUSIONS: Species ranges and assemblage composition appear driven primarily by phylogenetic niche conservatism. Closely related species are ecologically similar and occupy similar territories. The average level and geographic structure of plant phylogenetic diversity within Wisconsin are expected to greatly decline over the next half century, while potential species richness will increase throughout the state. Our methods can be applied to allochthonous communities throughout the world.


Assuntos
Evolução Biológica , Ecossistema , Traqueófitas/genética , Mudança Climática , Previsões , Filogeografia , Wisconsin
4.
Am J Bot ; 105(11): 1888-1910, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30368769

RESUMO

PREMISE OF THE STUDY: We present the first plastome phylogeny encompassing all 77 monocot families, estimate branch support, and infer monocot-wide divergence times and rates of species diversification. METHODS: We conducted maximum likelihood analyses of phylogeny and BAMM studies of diversification rates based on 77 plastid genes across 545 monocots and 22 outgroups. We quantified how branch support and ascertainment vary with gene number, branch length, and branch depth. KEY RESULTS: Phylogenomic analyses shift the placement of 16 families in relation to earlier studies based on four plastid genes, add seven families, date the divergence between monocots and eudicots+Ceratophyllum at 136 Mya, successfully place all mycoheterotrophic taxa examined, and support recognizing Taccaceae and Thismiaceae as separate families and Arecales and Dasypogonales as separate orders. Only 45% of interfamilial divergences occurred after the Cretaceous. Net species diversification underwent four large-scale accelerations in PACMAD-BOP Poaceae, Asparagales sister to Doryanthaceae, Orchidoideae-Epidendroideae, and Araceae sister to Lemnoideae, each associated with specific ecological/morphological shifts. Branch ascertainment and support across monocots increase with gene number and branch length, and decrease with relative branch depth. Analysis of entire plastomes in Zingiberales quantifies the importance of non-coding regions in identifying and supporting short, deep branches. CONCLUSIONS: We provide the first resolved, well-supported monocot phylogeny and timeline spanning all families, and quantify the significant contribution of plastome-scale data to resolving short, deep branches. We outline a new functional model for the evolution of monocots and their diagnostic morphological traits from submersed aquatic ancestors, supported by convergent evolution of many of these traits in aquatic Hydatellaceae (Nymphaeales).


Assuntos
Especiação Genética , Genomas de Plastídeos , Magnoliopsida/genética , Filogenia , DNA Intergênico , Zingiberales/genética
5.
Science ; 358(6370): 1535-1536, 2017 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-29269460
6.
Am J Bot ; 104(3): 354-366, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28232316

RESUMO

PREMISE OF THE STUDY: A recent commentary by Edwards et al. (Am. J. Bot. 103: 975-978) proposed that constraints imposed by the packing of young leaves in buds could explain the positive association between non-entire leaf margins and latitude but did not thoroughly consider alternative explanations. METHODS: We review the logic and evidence underlying six major hypotheses for the functional significance of marginal teeth, involving putative effects on (1) leaf cooling, (2) optimal support and supply of the areas served by major veins, (3) enhanced leaf-margin photosynthesis, (4) hydathodal function, (5) defense against herbivores, and (6) bud packing. KEY RESULTS: Theoretical and empirical problems undermine all hypotheses except the support-supply hypothesis, which implies that thinner leaves should have non-entire margins. Phylogenetically structured analyses across angiosperms, the El Yunque flora, and the genus Viburnum all demonstrate that non-entire margins are indeed more common in thinner leaves. Across angiosperms, the association of leaf thickness with non-entire leaf margins is stronger than that of latitude. CONCLUSION: We outline a synthetic model showing how biomechanics, hydraulics, vein geometry, rates of leaf expansion, and length of development within resting buds, all tied to leaf thickness, drive patterns in the distribution of entire vs. non-entire leaf margins. Our model accounts for dominance of entire margins in the tropics, Mediterranean scrub, and tundra, non-entire margins in cold temperate deciduous forests and tropical vines and early-successional trees, and entire leaf margins in monocots. Spinose-toothed leaves should be favored in short-statured evergreen trees and shrubs, primarily in Mediterranean scrub and related semiarid habitats.


Assuntos
Magnoliopsida/anatomia & histologia , Magnoliopsida/fisiologia , Fotossíntese/fisiologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Adaptação Fisiológica , Fenômenos Biomecânicos , Ecologia , Modelos Logísticos , Magnoliopsida/genética , Magnoliopsida/crescimento & desenvolvimento , Filogenia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Temperatura , Tilia
7.
Ecol Lett ; 20(3): 395-397, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28133897

RESUMO

Marks et al. (Ecol. Lett., 19, 2016, 743-751) show that tree diversity increases with tree height in North America and argue it reflects habitat 'suitability'. This finding conflicts with classical results, lacks controls for covariates of tree height, and can be explained alternatively using the modified Janzen-Connell effect and regional variance in habitats.


Assuntos
Ecossistema , Árvores , América do Norte
8.
Glob Chang Biol ; 23(3): 1305-1315, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27416325

RESUMO

Can species shift their distributions fast enough to track changes in climate? We used abundance data from the 1950s and the 2000s in Wisconsin to measure shifts in the distribution and abundance of 78 forest-understory plant species over the last half-century and compare these shifts to changes in climate. We estimated temporal shifts in the geographic distribution of each species using vectors to connect abundance-weighted centroids from the 1950s and 2000s. These shifts in distribution reflect colonization, extirpation, and changes in abundance within sites, separately quantified here. We then applied climate analog analyses to compute vectors representing the climate change that each species experienced. Species shifted mostly to the northwest (mean: 49 ± 29 km) primarily reflecting processes of colonization and changes in local abundance. Analog climates for these species shifted even further to the northwest, however, exceeding species' shifts by an average of 90 ± 40 km. Most species thus failed to match recent rates of climate change. These lags decline in species that have colonized more sites and those with broader site occupancy, larger seed mass, and higher habitat fidelity. Thus, species' traits appear to affect their responses to climate change, but relationships are weak. As climate change accelerates, these lags will likely increase, potentially threatening the persistence of species lacking the capacity to disperse to new sites or locally adapt. However, species with greater lags have not yet declined more in abundance. The extent of these threats will likely depend on how other drivers of ecological change and interactions among species affect their responses to climate change.


Assuntos
Mudança Climática , Ecossistema , Clima , Ecologia , Wisconsin
9.
Ecol Evol ; 6(10): 3367-79, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27103991

RESUMO

The amphicarpic annual legume Amphicarpaea bracteata is unusual in producing aerial and subterranean cleistogamous flowers that always self-fertilize and, less commonly, aerial chasmogamous flowers that outcross. Although both morphologic and genetic variants are known in this highly selfing species, debate continues over whether this variation is continuous, reflecting the segregation of standing genetic variation, or discontinuous, reflecting distinct taxa that rarely intercross. We characterized SNP variation in 128 individuals in southern Wisconsin to assess within- and among-population variation at 3928 SNPs. We also assessed genotype and leaf morphology in an additional 76 individuals to connect phenotypic variation with genetic variation. Genetic variation maps onto three strongly divergent and highly inbred genetic groups showing little relation to site location. Each group has a distinct phenotype, but the divergence of these groups differs from the varietal divisions previously identified based on morphological characters. Like previous authors, we argue that the taxonomy of this species should be revised. Despite extensive sympatry, estimates of among-group migration rates are low, and hybrid individuals were at low frequency (<2%) in our dataset. Restricted gene flow likely results from high selfing rates and partial reproductive incompatibility as evidenced by the U-shaped distribution of pairwise F ST values reflecting "islands" of genomic divergence. These islands may be associated with hybrid incompatibility loci that arose in allopatry. The coexistence of lineages within sites may reflect density-dependent attack by species-specific strains of pathogenic fungi and/or root-nodulating bacteria specializing on distinct genotypes.

10.
Plant Cell Environ ; 39(9): 2085-94, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27037757

RESUMO

Water plays a central role in plant biology and the efficiency of water transport throughout the plant affects both photosynthetic rate and growth, an influence that scales up deterministically to the productivity of terrestrial ecosystems. Moreover, hydraulic traits mediate the ways in which plants interact with their abiotic and biotic environment. At landscape to global scale, plant hydraulic traits are important in describing the function of ecological communities and ecosystems. Plant hydraulics is increasingly recognized as a central hub within a network by which plant biology is connected to palaeobiology, agronomy, climatology, forestry, community and ecosystem ecology and earth-system science. Such grand challenges as anticipating and mitigating the impacts of climate change, and improving the security and sustainability of our food supply rely on our fundamental knowledge of how water behaves in the cells, tissues, organs, bodies and diverse communities of plants. A workshop, 'Emerging Frontiers in Plant Hydraulics' supported by the National Science Foundation, was held in Washington DC, 2015 to promote open discussion of new ideas, controversies regarding measurements and analyses, and especially, the potential for expansion of up-scaled and down-scaled inter-disciplinary research, and the strengthening of connections between plant hydraulic research, allied fields and global modelling efforts.


Assuntos
Ecossistema , Árvores/fisiologia , Água/fisiologia , Ciclo Hidrológico
11.
Sci Adv ; 2(2): e1500975, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26989775

RESUMO

Patterns of biodiversity are changing rapidly. "Legacy studies" use historical data to document changes between past and present communities, revealing long-term trends that can often be linked to particular drivers of ecological change. However, a single pair of historical samples cannot ascertain whether rates of change are consistent or whether the impact and identity of drivers have shifted. Using data from a second resurvey of 47 Wisconsin prairie remnants, we show that the pace of community change has increased with shifts in the strength of particular drivers. Annual rates of local colonization and extinction accelerated by 129 and 214%, respectively, between 1950 and 1987 and between 1987 and 2012. Two anthropogenic drivers-patch area and fire history-increased in importance between these periods. As the strength and number of anthropogenic forces increase, rates of biodiversity change are likely to accelerate in other ecosystems as well.


Assuntos
Biodiversidade , Pradaria , Ecossistema , Extinção Biológica , Fogo , Plantas , Fatores de Tempo , Wisconsin
12.
Genome Biol Evol ; 8(4): 1150-64, 2016 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-26988252

RESUMO

Comparisons of flowering plant genomes reveal multiple rounds of ancient polyploidy characterized by large intragenomic syntenic blocks. Three such whole-genome duplication (WGD) events, designated as rho (ρ), sigma (σ), and tau (τ), have been identified in the genomes of cereal grasses. Precise dating of these WGD events is necessary to investigate how they have influenced diversification rates, evolutionary innovations, and genomic characteristics such as the GC profile of protein-coding sequences. The timing of these events has remained uncertain due to the paucity of monocot genome sequence data outside the grass family (Poaceae). Phylogenomic analysis of protein-coding genes from sequenced genomes and transcriptome assemblies from 35 species, including representatives of all families within the Poales, has resolved the timing of rho and sigma relative to speciation events and placed tau prior to divergence of Asparagales and the commelinids but after divergence with eudicots. Examination of gene family phylogenies indicates that rho occurred just prior to the diversification of Poaceae and sigma occurred before early diversification of Poales lineages but after the Poales-commelinid split. Additional lineage-specific WGD events were identified on the basis of the transcriptome data. Gene families exhibiting high GC content are underrepresented among those with duplicate genes that persisted following these genome duplications. However, genome duplications had little overall influence on lineage-specific changes in the GC content of coding genes. Improved resolution of the timing of WGD events in monocot history provides evidence for the influence of polyploidization on functional evolution and species diversification.


Assuntos
Evolução Molecular , Genoma de Planta , Magnoliopsida/genética , Transcriptoma , Duplicação Gênica , Oryza/genética , Filogenia , Poaceae/genética , Poliploidia , RNA de Plantas/genética , Sorghum/genética
13.
Mol Phylogenet Evol ; 95: 183-95, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26702956

RESUMO

The role of geography and ecology in speciation are often discussed in the context of phylogenetic niche conservatism (PNC), the propensity of lineages to retain ancestral niche related traits. However, a recent paradigm shift focuses instead on measuring divergence of these traits in conjunction with patterns of speciation. Under this framework, we analyzed the diversification of North America's third most diverse family, Cyperaceae ("sedges"), using a modified Parsimony Analysis of Endemicity approach to identify floristic regions and ordination statistics to quantify species distribution in a continuous manner. Utilizing over 200,000 georeferenced specimens, we characterized the geographical distribution and climatic and edaphic niche space occupied by each species. We constructed a supermatrix phylogeny of the North American sedge flora, aided in part by the sequencing of all sedges of Wisconsin, and employed a multifaceted approach to assess the role of geographical and ecological divergence on lineage diversification. In addition to measuring phylogenetic signal for these traits, we also measured pairwise phylogenetic distance of species within floristic regions, calculated rates of speciation, and tested for correlations of speciation rate to tempo of geographical and ecological evolution. Our analyses consistently show that evolutionarily related species tend to be geographically unrelated. Rates of geographical and ecological diversification are closely linked to tempo of speciation, and exploration of geographical place coincides with divergence in ecological niche space. We highlight the benefits of treating geography in a continuous manner, and stress the importance of employing a diverse suite of analytical approaches in testing hypotheses regarding the evolution of range and niche.


Assuntos
Carex (Planta)/classificação , Carex (Planta)/genética , Evolução Molecular , Especiação Genética , Cyperaceae/classificação , Cyperaceae/genética , Ecossistema , Geografia , América do Norte , Fenótipo , Filogenia , Filogeografia , Estados Unidos
14.
PLoS One ; 10(9): e0137963, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26368936

RESUMO

Ecologists have long classified Midwestern prairies based on compositional variation assumed to reflect local gradients in moisture availability. The best known classification is based on Curtis' continuum index (CI), calculated using the presence of indicator species thought centered on different portions of an underlying moisture gradient. Direct evidence of the extent to which CI reflects differences in moisture availability has been lacking, however. Many factors that increase moisture availability (e.g., soil depth, silt content) also increase nutrient supply and decrease soil mechanical impedance; the ecological effects of the last have rarely been considered in any ecosystem. Decreased soil mechanical impedance should increase the availability of soil moisture and nutrients by reducing the root costs of retrieving both. Here we assess the relative importance of soil moisture, nutrient supply, and mechanical impedance in determining prairie composition and structure. We used leaf δ13C of C3 plants as a measure of growing-season moisture availability, cation exchange capacity (CEC) x soil depth as a measure of mineral nutrient availability, and penetrometer data as a measure of soil mechanical impedance. Community composition and structure were assessed in 17 remnant prairies in Wisconsin which vary little in annual precipitation. Ordination and regression analyses showed that δ13C increased with CI toward "drier" sites, and decreased with soil depth and % silt content. Variation in δ13C among remnants was 2.0‰, comparable to that along continental gradients from ca. 500-1500 mm annual rainfall. As predicted, LAI and average leaf height increased significantly toward "wetter" sites. CI accounted for 54% of compositional variance but δ13C accounted for only 6.2%, despite the strong relationships of δ13C to CI and CI to composition. Compositional variation reflects soil fertility and mechanical impedance more than moisture availability. This study is the first to quantify the effects of soil mechanical impedance on community ecology.


Assuntos
Biodiversidade , Folhas de Planta/crescimento & desenvolvimento , Solo/química , Água/análise , Carbono/análise , Pradaria , Modelos Teóricos , Folhas de Planta/química , Wisconsin
15.
Proc Biol Sci ; 282(1814)2015 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-26311671

RESUMO

Orchids are the most diverse family of angiosperms, with over 25 000 species,more than mammals, birds and reptiles combined. Tests of hypotheses to account for such diversity have been stymied by the lack of a fully resolved broad-scale phylogeny. Here,we provide such a phylogeny, based on 75 chloroplast genes for 39 species representing all orchid subfamilies and 16 of 17 tribes, time-calibrated against 17 angiosperm fossils. Asupermatrix analysis places an additional 144 species based on three plastid genes. Orchids appear to have arisen roughly 112 million years ago (Mya); the subfamilies Orchidoideae and Epidendroideae diverged from each other at the end of the Cretaceous; and the eight tribes and three previously unplaced subtribes of the upper epidendroids diverged rapidly from each other between 37.9 and 30.8 Mya. Orchids appear to have undergone one significant acceleration of net species diversification in the orchidoids, and two accelerations and one deceleration in the upper epidendroids. Consistent with theory, such accelerations were correlated with the evolution of pollinia, the epiphytic habit, CAM photosynthesis, tropical distribution (especially in extensive cordilleras),and pollination via Lepidoptera or euglossine bees. Deceit pollination appears to have elevated the number of orchid species by one-half but not via acceleration of the rate of net diversification. The highest rate of net species diversification within the orchids (0.382 sp sp(-1) My(-1)) is 6.8 times that at the Asparagales crown.


Assuntos
Evolução Biológica , Orchidaceae/classificação , Orchidaceae/genética , Filogenia , Animais , Abelhas , Cloroplastos/genética , Decepção , Genoma de Planta , Lepidópteros , Fotossíntese , Polinização/genética , Fatores de Tempo
16.
New Phytol ; 207(2): 297-303, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26032979

RESUMO

Adaptive radiation is the rise of a diversity of ecological roles and role-specific adaptations within a lineage. Recently, some researchers have begun to use 'adaptive radiation' or 'radiation' as synonymous with 'explosive species diversification'. This essay aims to clarify distinctions between these concepts, and the related ideas of geographic speciation, sexual selection, key innovations, key landscapes and ecological keys. Several examples are given to demonstrate that adaptive radiation and explosive diversification are not the same phenomenon, and that focusing on explosive diversification and the analysis of phylogenetic topology ignores much of the rich biology associated with adaptive radiation, and risks generating confusion about the nature of the evolutionary forces driving species diversification. Some 'radiations' involve bursts of geographic speciation or sexual selection, rather than adaptive diversification; some adaptive radiations have little or no effect on speciation, or even a negative effect. Many classic examples of 'adaptive radiation' appear to involve effects driven partly by geographic speciation, species' dispersal abilities, and the nature of extrinsic dispersal barriers; partly by sexual selection; and partly by adaptive radiation in the classical sense, including the origin of traits and invasion of adaptive zones that result in decreased diversification rates but add to overall diversity.


Assuntos
Adaptação Fisiológica , Biodiversidade , Evolução Biológica , Filogenia , Plantas/genética , Ecologia , Especiação Genética , Lupinus/genética , Fenótipo , Filogeografia
17.
New Phytol ; 207(1): 43-58, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25858142

RESUMO

Leaf hydraulic conductance (Kleaf ) quantifies the capacity of a leaf to transport liquid water and is a major constraint on light-saturated stomatal conductance (gs ) and photosynthetic rate (Amax ). Few studies have tested the plasticity of Kleaf and anatomy across growth light environments. These provided conflicting results. The Hawaiian lobeliads are an excellent system to examine plasticity, given the striking diversity in the light regimes they occupy, and their correspondingly wide range of Amax , allowing maximal carbon gain for success in given environments. We measured Kleaf , Amax , gs and leaf anatomical and structural traits, focusing on six species of lobeliads grown in a common garden under two irradiances (300/800 µmol photons m(-2)  s(-1) ). We tested hypotheses for light-induced plasticity in each trait based on expectations from optimality. Kleaf , Amax , and gs differed strongly among species. Sun/shade plasticity was observed in Kleaf , Amax, and numerous traits relating to lamina and xylem anatomy, venation, and composition, but gs was not plastic with growth irradiance. Species native to higher irradiance showed greater hydraulic plasticity. Our results demonstrate that a wide set of leaf hydraulic, stomatal, photosynthetic, anatomical, and structural traits tend to shift together during plasticity and adaptation to diverse light regimes, optimizing performance from low to high irradiance.


Assuntos
Campanulaceae/fisiologia , Fenômenos Ecológicos e Ambientais , Gases/metabolismo , Luz , Folhas de Planta/anatomia & histologia , Folhas de Planta/efeitos da radiação , Feixe Vascular de Plantas/fisiologia , Biodiversidade , Campanulaceae/crescimento & desenvolvimento , Campanulaceae/efeitos da radiação , Geografia , Folhas de Planta/fisiologia , Feixe Vascular de Plantas/efeitos da radiação , Característica Quantitativa Herdável , Chuva , Especificidade da Espécie , Água
19.
Appl Plant Sci ; 2(10)2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25309836

RESUMO

PREMISE OF THE STUDY: The chemical diversity of land plants ensures that no single DNA isolation method results in high yield and purity with little effort for all species. Here we evaluate a new technique originally developed for forensic science, based on MagnaCel paramagnetic cellulose particles (PMC), to determine its efficacy in extracting DNA from 25 plant species representing 21 families and 15 orders. • METHODS AND RESULTS: Yield and purity of DNA isolated by PMC, DNeasy Plant Mini Kit (silica column), and cetyltrimethylammonium bromide (CTAB) methods were compared among four individuals for each of 25 plant species. PMC gave a twofold advantage in average yield, and the relative advantage of the PMC method was greatest for samples with the lowest DNA yields. PMC also produced more consistent sample purity based on absorbance ratios at 260:280 and 260:230 nm. • CONCLUSIONS: PMC technology is a promising alternative for plant DNA isolation.

20.
Am J Bot ; 101(7): 1189-1199, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25002460

RESUMO

• Premise of the study: Tropical forests are the most species-rich terrestrial communities on Earth, and understory trees and shrubs comprise a large fraction of their plant species diversity, especially at high rainfalls. The mechanisms responsible for generating such high levels of diversity remain unknown. One hypothesis is that fleshy-fruited understory species should have limited seed dispersal due to the sedentary nature of their avian dispersers, resulting in restricted gene flow, population differentiation at small spatial scales, and ultimately, high rates of allopatric speciation.• Methods: We sampled four species of the hyperdiverse tropical shrub genus Psychotria (Rubiaceae) on Barro Colorado Island (BCI) and two nearby sites in Panama. We genotyped each species with AFLPs, assessed genetic differentiation among populations, and determined patterns of fine-scale spatial genetic structure in the BCI population. Measures of spatial autocorrelation and population density were used to estimate the dispersal distance parameter σ.• Key results: Regionally, ΦPT values ranged from 0.13 to 0.28, reflecting local population differentiation and suggesting that Lake Gatun/Rio Chagres has posed a relatively strong barrier to gene flow. Fine-scale spatial genetic structure on BCI was stronger than in most canopy trees, and estimated distances of gene flow were unusually low for endozoochorous tropical woody plants, with dispersal distance σ = 9-113 m.• Conclusions: These results demonstrate comparatively limited gene flow in bird-dispersed understory species, supporting a hypothesized mechanism for generating high levels of plant species diversity in tropical rain forests, in one of the largest genera of flowering plants on Earth.

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