Biology subjects

Johnson, J. A.

Publications and source records attributed to Johnson, J. A..

23 records · Page 2Linked to original sources

bioRxiv2019

Mitochondrial phylogeography reveals high diversity and unique divergent lineage in Indian Dugongs (Dugong dugon)

O_LIIndia plays a central role in dugong conservation by hosting the largest population within south Asia. Current knowledge on status of Indian dugongs is limited due to paucity of reliable ecological data. This study generates mitochondrial control region sequences from about 10% of dugong population from major dugong populations within India. These data was compared with the global data to assess genetic lineages, population structure and genetic diversity of Indian populations. C_LIO_LIMultiple analyses suggest that the Indian dugong populations are part of a single genetic cluster, comprising south Asia, northwest Indian ocean and southwest Indian ocean populations. Despite small population size, they retain high genetic diversity with unique mitochondrial DNA haplotypes within south Asia. C_LIO_LIWithin India, novel haplotypes were observed from all sampling sites with overall high haplotype diversity (0.85{+/-}0.04) but low nucleotide diversity (0.005{+/-}0.001). Indian populations exhibit high genetic differentiation with higher within-population variance (63.41%) than among populations (36.59%), signaling population structure. Few haplotypes were shared with Sri Lanka and southeast Asian populations, indicating potential genetic connectivity. C_LIO_LIBeing the most genetically unique population within south Asia, Indian dugong populations are globally significant. We recommend that Indian Dugong populations should be managed as a Conservation Unit to ensure population recovery and long-term survival of the species. C_LI

molecular biology↗

bioRxiv2019

Globally Harmonized Carbon Storage Data using a Simple Decision Tree Approach

This paper presents methods and results that combine multiple carbon storage and above-ground biomass datasets using a simple decision tree approach. The resulting dataset combines the positive attributes of the multiple input datasets in order to have global, high-resolution extent while utilizing the best statistical methods where possible. Visual inspection shows very different spatial configurations of carbon storage between the results and the input data, suggesting that combination of methods can improve estimates. The summation of the decision tree result was 336.55 petagrams while the summation of a dataset based on the IPCC Tier 1 method was 502.38 petagrams (49.27% higher than the results from the decision tree).

ecology↗

bioRxiv2019

No evidence for disruption of global patterns of nest predation in shorebirds

Kubelka et al. (Science, 9 November 2018, p. 680-683) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.

ecology↗

bioRxiv2018

A protocol for an intercomparison of biodiversity and ecosystem services models using harmonized land-use and climate scenarios

Abstract.To support the assessments of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the IPBES Expert Group on Scenarios and Models is carrying out an intercomparison of biodiversity and ecosystem services models using harmonized scenarios (BES-SIM). The goals of BES-SIM are (1) to project the global impacts of land use and climate change on biodiversity and ecosystem services (i.e. natures contributions to people) over the coming decades, compared to the 20th century, using a set of common metrics at multiple scales, and (2) to identify model uncertainties and research gaps through the comparisons of projected biodiversity and ecosystem services across models. BES-SIM uses three scenarios combining specific Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs) to explore a wide range of land-use change and climate change futures. This paper describes the rationale for scenarios selection, the process of harmonizing input data for land use, based on the second phase of the Land Use Harmonization Project (LUH2), and climate, the biodiversity and ecosystem service models used, the core simulations carried out, the harmonization of the model output metrics, and the treatment of uncertainty. The results of this collaborative modelling project will support the ongoing global assessment of IPBES, strengthen ties between IPBES and the Intergovernmental Panel on Climate Change (IPCC) scenarios and modelling processes, advise the Convention on Biological Diversity (CBD) on its development of a post-2020 strategic plans and conservation goals, and inform the development of a new generation of nature-centred scenarios.

ecology↗

bioRxiv2016

Unexpected diversity in socially synchronized rhythms of shorebirds

The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment1-4. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions1,5, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators6-10. Individuals can temporally segregate their daily activities (e.g. prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (e.g. group foraging, communal defence, pairs reproducing or caring for offspring)6-9,11. The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood5-7,9. Here, we address this in the context of biparental care, a particularly sensitive phase of social synchronization12 where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally-incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within- and between-species diversity in incubation rhythms. Between species, the median length of one parents incubation bout varied from 1 - 19 hours, while period length-the time in which a parents probability to incubate cycles once between its highest and lowest value - varied from 6 - 43 hours. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or actively protect their nest against predators. Rhythms entrainable to the 24-h light-dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity5-7,9. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms.

animal behavior and cognition↗