Dataset Information

The importance of observation versus process error in analyses of global ungulate populations.

ABSTRACT: Population abundance data vary widely in quality and are rarely accurate. The two main components of error in such data are observation and process error. We used Bayesian state space models to estimate the observation and process error in time-series of 55 globally distributed populations of two species, Cervus elaphus (elk/red deer) and Rangifer tarandus (caribou/reindeer). We examined variation among populations and species in the magnitude of estimates of error components and density dependence using generalized linear models. Process error exceeded observation error in 75% of all populations, and on average, both components of error were greater in Rangifer than in Cervus populations. Observation error differed significantly across the different observation methods, and predation and time-series length differentially affected the error components. Comparing the Bayesian model results to traditional models that do not separate error components revealed the potential for misleading inferences about sources of variation in population dynamics.

SUBMITTER: Ahrestani FS

PROVIDER: S-EPMC6506149 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The importance of observation versus process error in analyses of global ungulate populations.

Ahrestani Farshid S FS Hebblewhite Mark M Post Eric E

Scientific reports 20131108

Population abundance data vary widely in quality and are rarely accurate. The two main components of error in such data are observation and process error. We used Bayesian state space models to estimate the observation and process error in time-series of 55 globally distributed populations of two species, Cervus elaphus (elk/red deer) and Rangifer tarandus (caribou/reindeer). We examined variation among populations and species in the magnitude of estimates of error components and density depende ...[more]

PMID: 24201239

Similar Datasets

Project description:Coupled motions have been demonstrated to be functionally important in a number of enzymes. Noncovalent side-chain interactions play essential roles in coordinating the motions across different structural elements in a protein. However, most of the dynamic studies of proteins are focused on backbone amides or methyl groups in the side chains and little is known about the polar and charged side chains. We have previously characterized the conformational dynamics of deubiquitinase A (DUBA), an isopeptidase, on the microsecond-to-millisecond (μs-ms) time scales with the amide 1H Carr-Purcell-Meiboom-Gill (CPMG) experiment. We detected a global conformational exchange process on a time scale of approximately 200 μs, which involves most of the structural elements in DUBA, including the active site and the substrate binding interface. Here, we extend our previous study on backbone amides to the arginine side-chain Nε-Hε groups using a modified 1H CPMG pulse sequence that can efficiently detect both backbone amide and arginine side-chain Nε-Hε signals in a single experiment. We found that the side chains of three arginines display motions on the same time scale as the backbone amides. Mutations of two of the three arginines to alanines result in a decrease in enzyme activity. One of these two arginines is located in a loop involved in substrate binding. This loop is not visible in the backbone amide-detected experiments due to excess line broadening induced by motions on the μs-ms time scales. These results clearly demonstrate that the motions of some arginine side chains are coupled to the global conformational exchange process and provide an additional probe for motions in a functionally important loop that did not yield visible backbone amide signals, suggesting the value of side-chain experiments on DUBA. The modified 1H CPMG pulse sequence allows the simultaneous characterization of backbone and arginine side-chain dynamics without any increase in data acquisition time and can be applied to the dynamic studies of any protein that displays measurable amide 1H relaxation dispersion.

Project description:The ecological integrity of US national parks and other protected areas are under threat in the Anthropocene. For Yellowstone National Park (YNP), the impacts that global change has already had on the park's capacity to sustain its large migratory herds of wild ungulates is incompletely understood. Here we examine how two understudied components of global change, the historical increase in atmospheric CO2 and the spread of nonnative, invasive plant species, may have altered the capacity of YNP to provide forage for ungulates over the last 200-plus years. We performed two experiments: (1) a growth chamber study that determined the growth rates of important invasive and native YNP grasses that are forages for ungulates under preindustrial (280 ppm) versus modern (410 ppm) CO2 levels and (2) a field study that compared the effect of defoliation (clipping) on the shoot growth of invasive and native mesic grassland plants under ambient CO2 conditions in 2019. The growth chamber experiment revealed that modern CO2 increased the growth rates of both invasive and native grasses, and invasive grasses grew faster regardless of CO2 conditions. The field results showed a continuum of positive to negative responses of shoot growth to defoliation, with a subgroup of invasive species responding most positively. Altogether the results indicated that the historical increase in CO2 and the spread of invasive species, some of which were planted to provide forage for ungulates in the early and mid-1900s, have likely increased the capacity of forage production in YNP. However, rising CO2 has also resulted in regional warming and increased aridity in YNP, which will likely reduce grassland productivity. The challenge for global change biologists and park managers is to determine how competing components of global change have already affected and will increasingly affect forage dynamics and the sustainability of Yellowstone's iconic ungulate herds in the Anthropocene.

Dataset Information

The importance of observation versus process error in analyses of global ungulate populations.

Publications

The importance of observation versus process error in analyses of global ungulate populations.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets