Corlett R.T.,CAS Xishuangbanna Tropical Botanical Garden
Trends in Ecology and Evolution | Year: 2016
The increasing abandonment of marginal land creates new opportunities for restoration, reintroduction, and rewilding, but what do these terms mean in a rapidly and irreversibly changing world? The 're' prefix means 'back', but it is becoming clear that the traditional use of past ecosystems as targets and criteria for success must be replaced by an orientation towards an uncertain future. Current opinions in restoration and reintroduction biology range from a defense of traditional definitions, with some modifications, to acceptance of more radical responses, including assisted migration, taxon substitution, de-extinction, and genetic modification. Rewilding attempts to minimize sustained intervention, but this hands-off approach is also threatened by rapid environmental change. Abandonment of agricultural land provides an opportunity for creating new ecosystems, but the traditional use of past ecosystems as targets is likely to be inappropriate in a time of rapid environmental change.There is no agreement among conservationists about how to replace the historically based reference frame, with opinions ranging from minor modification to the acceptance of increasingly radical alternatives including moving species outside their current native ranges, using non-native taxon substitutions to maintain key functions, and the acceptance of novel ecosystems that are different from any past analogs.New technologies will facilitate the genetic modification of threatened species and make the 'de-extinction' of at least some species possible, providing new, controversial options for conservationists.Future debates seem likely to increasingly focus on the degree of human intervention that is desirable as 'wildness' is seen as an increasingly important attribute. Rewilding attempts to minimize sustained intervention, but this approach is also threatened by rapid environmental change. © 2016 Elsevier Ltd.
Ives A.R.,University of Wisconsin - Madison |
Helmus M.R.,CAS Xishuangbanna Tropical Botanical Garden
Ecological Monographs | Year: 2011
There is growing appreciation that ecological communities are phylogenetically structured, with phylogenetically closely related species either more or less likely to co-occur at the same site. Here, we present phylogenetic generalized linear mixed models (PGLMMs) that can statistically test a wide variety of phylogenetic patterns in community structure. In contrast to most current statistical approaches that rely on community metrics and randomization tests, PGLMMs are model-based statistics that fit observed presence/absence data to underlying hypotheses about the distributions of species among communities. We built four PGLMMs to address (1) phylogenetic patterns in community composition, (2) phylogenetic variation in species sensitivities to environmental gradients among communities, (3) phylogenetic repulsion in which closely related species are less likely to co-occur, and (4) trait-based variation in species sensitivities to environmental gradients. We also built a fifth PGLMM to test a key underlying assumption of phylogenetic community structure: that phylogenetic information serves as a surrogate for trait information about species; this model tests whether the introduction of trait information can explain all variation in species occurrences among communities, leaving no phylogenetic residual variation. We assessed the performance of these PGLMMs using community simulation models and show that PGLMMs have equal or greater statistical power than alternative approaches currently in the literature. Finally, we illustrate the PGLMM advantage of fitting a model to data by showing how variation in species occurrences among communities can be partitioned into phylogenetic and site-specific components, and how fitted models can be used to predict the co-occurrence of phylogenetically related species. © 2011 by the Ecological Society of America.
Xu Z.-F.,CAS Xishuangbanna Tropical Botanical Garden
BMC genomics | Year: 2014
BACKGROUND: Jatropha curcas, whose seed content is approximately 30-40% oil, is an ideal feedstock for producing biodiesel and bio-jet fuels. However, Jatropha plants have a low number of female flowers, which results in low seed yield that cannot meet the needs of the biofuel industry. Thus, increasing the number of female flowers is critical for the improvement of Jatropha seed yield. Our previous findings showed that cytokinin treatment can increase the flower number and female to male ratio and also induce bisexual flowers in Jatropha. The mechanisms underlying the influence of cytokinin on Jatropha flower development and sex determination, however, have not been clarified.RESULTS: This study examined the transcriptional levels of genes involved in the response to cytokinin in Jatropha inflorescence meristems at different time points after cytokinin treatment by 454 sequencing, which gave rise to a total of 294.6 Mb of transcript sequences. Up-regulated and down-regulated annotated and novel genes were identified, and the expression levels of the genes of interest were confirmed by qRT-PCR. The identified transcripts include those encoding genes involved in the biosynthesis, metabolism, and signaling of cytokinin and other plant hormones, flower development and cell division, which may be related to phenotypic changes of Jatropha in response to cytokinin treatment. Our analysis indicated that Jatropha orthologs of the floral organ identity genes known as ABCE model genes, JcAP1,2, JcPI, JcAG, and JcSEP1,2,3, were all significantly repressed, with an exception of one B-function gene JcAP3 that was shown to be up-regulated by BA treatment, indicating different mechanisms to be involved in the floral organ development of unisexual flowers of Jatropha and bisexual flowers of Arabidopsis. Several cell division-related genes, including JcCycA3;2, JcCycD3;1, JcCycD3;2 and JcTSO1, were up-regulated, which may contribute to the increased flower number after cytokinin treatment.CONCLUSIONS: This study presents the first report of global expression patterns of cytokinin-regulated transcripts in Jatropha inflorescence meristems. This report laid the foundation for further mechanistic studies on Jatropha and other non-model plants responding to cytokinin. Moreover, the identification of functional candidate genes will be useful for generating superior varieties of high-yielding transgenic Jatropha.
Corlett R.T.,CAS Xishuangbanna Tropical Botanical Garden
Biological Conservation | Year: 2013
The majority of terrestrial ecosystems outside Africa have lost megafaunal vertebrates (>44. kg) since the Middle Pleistocene and most of these extinctions can be attributed to human influence. This review assesses the likely impacts of prehistoric megafaunal extinctions in the lowland tropics and discusses the implications for contemporary conservation management. The most likely impacts include: the coextinction of parasites, a reduction in environmental heterogeneity, the release of competitors and prey (including plants), and a loss of quality and quantity in seed dispersal services. This, however, is based largely on arguments by analogy with the surviving megafauna, since the impacts of megafaunal losses are compounded in the paleoenvironmental record with changes in climate and other human impacts. Suggested conservation responses include: prioritizing the conservation of the surviving megafaunal species and reintroducing them, where possible, into parts of their former ranges; reversible experiments with the introduction of taxon substitutes outside their natural ranges; and special conservation attention to megafaunal-dependent orphans and anachronisms. © 2012 Elsevier Ltd.
Song Y.,CAS Xishuangbanna Tropical Botanical Garden
Journal of Integrative Plant Biology | Year: 2014
2,4-Dichlorophenoxyacetic acid (2,4-D) was the first synthetic herbicide to be commercially developed and has commonly been used as a broadleaf herbicide for over 60 years. It is a selective herbicide that kills dicots without affecting monocots and mimics natural auxin at the molecular level. Physiological responses of dicots sensitive to auxinic herbicides include abnormal growth, senescence, and plant death. The identification of auxin receptors, auxin transport carriers, transcription factors response to auxin, and cross-talk among phytohormones have shed light on the molecular action mode of 2,4-D as a herbicide. Here, the molecular action mode of 2,4-D is highlighted according to the latest findings, emphasizing the physiological process, perception, and signal transduction under herbicide treatment. © 2013 Institute of Botany, Chinese Academy of Sciences.
Harrison R.D.,CAS Xishuangbanna Tropical Botanical Garden
BioScience | Year: 2011
More than 18% of tropical rainforests are now covered by totally protected areas. If these were well protected, we could feel reasonably confident that current conservation strategies might succeed in preserving a substantial proportion of tropical biodiversity. However, in most parts of the tropics, poachers enter and leave reserves with impunity. On the basis of reports from the hunting literature, it seems likely that a majority of tropical nature reserves may already be considered empty forestsmeaning that all bird and mammal species larger than approximately two kilogramsbarring a few hunting-tolerant specieshave either been extirpated or exist at densities well below natural levels of abundance. The disruption of ecological functions caused by the loss of symbionts further compromises the capacity of these reserves to conserve biodiversity over the long term. A substantial shift toward improving the management and enforcement of tropical protected-area networks is required. © 2011 by American Institute of Biological Sciences. All rights reserved.
Corlett R.T.,CAS Xishuangbanna Tropical Botanical Garden
Trends in Ecology and Evolution | Year: 2015
The term 'Anthropocene' was first used in the year 2000 to refer to the current time period in which human impacts are at least as important as natural processes. It is currently being considered as a potential geological epoch, following on from the Holocene. While most environmental scientists accept that many key environmental parameters are now outside their Holocene ranges, there is no agreement on when the Anthropocene started, with plausible dates ranging from the Late Pleistocene megafaunal extinctions to the recent globalization of industrial impacts. In ecology, the Anthropocene concept has focused attention on human-dominated habitats and novel ecosystems, while in conservation biology it has sparked a divisive debate on the continued relevance of the traditional biocentric aims. © 2014 Elsevier Ltd.
Cai Z.Q.,CAS Xishuangbanna Tropical Botanical Garden
Industrial Crops and Products | Year: 2011
We examined variation in the flowering phenology of Sacha Inchi (Plukenetia volubilis) plants monitored during an 8-month period with reference to a light gradient (20%, 52%, 75% and 100% of full sunlight), and related these results to photosynthetic features, growth and fruit yield. With strong phenotypically plastic response to light, relative growth rate and photosynthetic capability continually increased with increasing irradiance and their maximum values were much similar to those of the pioneer species. Shade did not increase the apparent quantum yield and reduce the light saturation point and respiration rate. Thus, it was suggested that P. volubilis is a high-light demanding species. Shade delayed initial flowering date and decreased flower and fruit parts. An earlier initiation of flowering was associated with higher flower biomass and plant total biomass, in turn; the latter was positively correlated with fruit biomass across light gradients. These results suggested that an optimized crop management practice should be adopted to ensure that P. volubilis be grown under conditions with minimal shading. © 2011 Elsevier B.V.
Zhu H.,CAS Xishuangbanna Tropical Botanical Garden
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2013
The distribution patterns of geographical elements of seed plants from 135 regional floras that cover southern China were used to reassess the extent and boundaries of the tropical zone. The areas for which tropical genera account for >. 80% of the total genera in the flora are south of 22°30'N in southern and southeastern China, which corresponds closely to the northern boundary of the tropical monsoon forest and rain forest in southeastern China. The line at c. 22°30'N is therefore suggested to be the northern biogeographical boundary of the tropical zone in south and southeastern China. This line exceeds the northern boundary of marginal tropical climate, which implies that the tropical zone could have extended further north in the geological past than it does today. The study supports the suggestion from palaeoecological studies that tropical and subtropical broadleaved evergreen forests in eastern China shifted north during the mid-Holocene. It also shows that there are climatic and biogeographical disparities between southeastern and southwestern China due to their different topography and geology. © 2013 Elsevier B.V.
Corlett R.T.,CAS Xishuangbanna Tropical Botanical Garden |
Trends in Ecology and Evolution | Year: 2013
In the face of anthropogenic climate change, species must acclimate, adapt, move, or die. Although some species are moving already, their ability to keep up with the faster changes expected in the future is unclear. 'Migration lag' is a particular concern with plants, because it could threaten both biodiversity and carbon storage. Plant movements are not realistically represented in models currently used to predict future vegetation and carbon-cycle feedbacks, so there is an urgent need to understand how much of a problem failure to track climate change is likely to be. Therefore, in this review, we compare how fast plants need to move with how fast they can move; that is, the velocity of climate change with the velocity of plant movement. © 2013 Elsevier Ltd.