ABSTRACT
This paper addresses an important debate in Amazonian studies; namely, the scale, intensity, and nature of human modification of the forests in prehistory. Phytolith and charcoal analysis of terrestrial soils underneath mature tierra firme (nonflooded, nonriverine) forests in the remote Medio Putumayo-Algodón watersheds, northeastern Peru, provide a vegetation and fire history spanning at least the past 5,000 y. A tree inventory carried out in the region enables calibration of ancient phytolith records with standing vegetation and estimates of palm species densities on the landscape through time. Phytolith records show no evidence for forest clearing or agriculture with major annual seed and root crops. Frequencies of important economic palms such as Oenocarpus, Euterpe, Bactris, and Astrocaryum spp., some of which contain hyperdominant species in the modern flora, do not increase through prehistoric time. This indicates pre-Columbian occupations, if documented in the region with future research, did not significantly increase the abundance of those species through management or cultivation. Phytoliths from other arboreal and woody species similarly reflect a stable forest structure and diversity throughout the records. Charcoal 14C dates evidence local forest burning between ca. 2,800 and 1,400 y ago. Our data support previous research indicating that considerable areas of some Amazonian tierra firme forests were not significantly impacted by human activities during the prehistoric era. Rather, it appears that over the last 5,000 y, indigenous populations in this region coexisted with, and helped maintain, large expanses of relatively unmodified forest, as they continue to do today.
Subject(s)
Fires , Forests , Anthropogenic Effects , PeruABSTRACT
The forests of Amazonia are among the most biodiverse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary biodiversity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 'hyperdominant' species account for >50% of all individuals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations.
Subject(s)
Forests , Trees , Biodiversity , Brazil , HumansABSTRACT
Durante el período 2000 - 2016, se llevaron a cabo 15 inventarios biológicos en áreas remotas en el pie de monte andino y el llano amazónico del Perú. En estos inventarios, 27 botánicos colectaron un total de 9397 especímenes de plantas vasculares fértiles. Hasta finales del 2017, más de la mitad de estos especímenes se han identificado a nivel de especie, de los cuales 64 especies y 2 géneros (Dicorynia y Monopteryx) representan nuevos registros para la flora del Perú. Si esta tasa de novedades se mantiene, el número de registros nuevos en el material de los inventarios podría aumentar, lo cual nos indica que aún queda mucho por descubrir en la flora andino-amazónica del Perú.
Between 2000 and 2016 we carried out 15 rapid biological inventories in remote areas of the Andean foothills and Amazon basin in Peru. During these inventories, 27 botanists collected 9397 fertile vascular plant specimens. By the end of 2017, more than half of these specimens had been identified to species. Of the 2303 species identified to date, 64 species and 2 genera (Dicorynia and Monopteryx) are new records for the flora of Peru. If this rate of discovery proves typical, the number of new records for Peru in the rapid inventory material could increase, which indicates that there is still much to discover in the Peruvian flora.
ABSTRACT
Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is a sensitive and accurate tool for quantitative estimation of gene transcription levels in preimplantation embryos. To control for possible experimental variations, gene expression data must be normalized using internal control genes commonly known as reference genes. However, the stability of reference genes can vary depending on the state of development and/or experimental conditions; hence the assessment of their stability is essential before initiating a gene expression analysis. In the present study, we used RT-qPCR to measure the transcript levels of 10 commonly used reference genes and analyzed their expression stability in bovine blastocysts produced by in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT). Using the geNorm program, we found the best combination of genes to normalize gene expression data in bovine embryos at the blastocyst stage produced by IVF (HMBS, SF3A1, and HPRT1), ICSI (H2A, HMBS, and GAPDH), SCNT (ACTB, SF3A1, and SDHA) and/or between blastocysts produced by these methods (GAPDH, HMBS and EEF1A2). We also demonstrated that not only the culture conditions may affect the expression patterns in bovine blastocysts but also the choice of embryo production method may have an important effect.