Assessment of climate change impact on the malaria vector Anopheles hyrcanus, West Nile disease, and incidence of melanoma in the Vojvodina Province (Serbia) using data from a regional climate model 

By: Dragutin T. Mihailović, Dusan Petrić, Tamas Petrović, Ivana Hrnjaković- Cvjetković, Vladimir Djurdjevic, Emilija Nikolić-Đoric, Ilija Arsenić, Mina PetrićID, Gordan Mimić, Aleksandra Ignjatović-Cupina 

Summarized by: Kailey McCain

What data were used? Researchers assessed climate change and UV radiation (UVR) and compared it to data collected over ten years from mosquito field collections at over 166 sites across Serbia. Additionally, public health records for the circulation of vector-borne disease (I.e., illnesses spread by mosquitoes and ticks), specifically the West Nile Virus, and the incidence of melanoma (i.e., a serious form of skin cancer) were collected and compared.

Methods: The climate change and UVR doses were collected by using EBU-POM model (a type of regional climate model) for the time periods: 1961-2000 and 2001-2030. As for the collection of the mosquito data, two different dry-ice baited traps (dry-ice is a solid form of carbon dioxide, which is a natural attractive substance for mosquitos) were used. The various sites were chosen by entomologists (i.e., scientists who study insects) to obtain a diverse data set. The mosquitoes collected were then anesthetised, separated by location, species, sex, and then tested for a specific RNA (I.e., a single stranded molecule) strand that would indicate the mosquito was carrying the West Nile Virus.

Furthermore, the researchers measured the rate of melanoma incidences in Serbia by using two different indicators: new number of cases versus time and number of new cases versus population size. The defined time period for data collection was 10 years (1995-2004). With this data, the researchers compared the rate of incidence to the climate data previously collected.

Results: From the data collected via the regional climate model, a linear upwards trend in temperature in Serbia was recorded. The prevalence of mosquitoes was also found to increase linearly throughout the time period. The culmination of these results can be seen in figure 1.

As for the melanoma data, the researchers found a linear increase in UVR doses for the time period. This data was found to be correlated to an increase in melanoma incidences throughout Serbia and this data can be visualized in figure 2.

Why is this study important? Disease prevalence and distribution have always been difficult to predict due to the varying ecological factors that play important roles. Research like this is especially important because it allows scientists to simulate future spreads of vector-borne diseases within European countries. This can eventually lead to the development of public health surveillance technology and overall prevention.

The big picture: This study aimed to correlate changes in temperature and UV radiation to the spread of diseases and cancer. With vector-borne diseases being the most sensitive to ecological conditions, researchers chose the West Nile Virus to act as a proxy to all mosquito transmitted diseases. As expected, the data supports the claim that increased temperatures trigger an enhanced risk for not only infectious diseases, but certain cancers as well.

Citation: Mihailović, D. T., Petrić, D., Petrović, T., Hrnjaković-Cvjetković, I., Djurdjevic, V., Nikolić-Đorić, E., Arsenić, I., Petrić, M., Mimić, G., & Ignjatović-Ćupina, A. (2020). Assessment of climate change impact on the malaria vector Anopheles hyrcanus, West Nile disease, and incidence of melanoma in the Vojvodina Province (Serbia) using data from a regional climate model. PLoS ONE, 15(1), 1–17. https://doi.org/10.1371/journal.pone.0227679

Temporal shifts in the distribution of murine rodent body size classes at Liang Bua (Flores, Indonesia) reveal new insights into the paleoecology of Homo floresiensis and associated fauna

by: E. Grace Veatch, Matthew W. Tocheri, Thomas Sutikna, Kate McGrath, E. Wahyu Saptomo, Jatmiko, and Kristofer M. Helgen.

Summarized by: Kailey McCain

What data were used? Researchers once believed that Homo sapiens (i.e., modern humans) were the only hominid to reach the Indonesian islands. However, in the past few decades anthropologists, archeologists, and paleontologists have discovered an early hominid species’ cultural and skeletal remains, belonging to Homo floresiensis, on the island of Flores. Along with the hominid remains, 257,000 additional vertebrate skeletal elements were identified and 80% of the collected belonged to the murine rodent taxa (i.e., rats). The main rodent genera identified and used in this study varied in body size, which was used as a proxy (i.e., representative) to identify the paleoecology of the environment. The five genera used were: Papagomys, Spelaeomys, Hooijeromys, Komodomys, Paulamys, and Rattus (Figure 1).

Methods: The excavation site for the murine skeletal remains, as well as H. floresiensis, was within the Liang Bua, a limestone cave on Flores Island. The stratigraphy of Liang Bua was divided into sectors based on age, with the oldest being approximately 190-120 ka (thousand years ago) and the youngest sector at less than 3 ka. Once the sites were identified, researchers began excavating the remains by using a method called wet-sieving, which is the process of sediment separation using water to remove certain grain sizes and break apart agglomerates (i.e., a mass of sediment grains).

Once the murine remains were collected, researchers began identifying the different species by using molar and jaw sizes, as well as comparing the skeletal body to size to extant (i.e., living) rodents. In addition to dividing the remains into their different species, they were also further divided by size. The five distinct body size categories are: small (<100 g), medium (100-300 g), large (300-600 g), huge (600-1100 g), and giant (>1100 g).

Results: The data collected showed that the small and medium sized murines dominated the cave during the first two sectors (190-60 ka) but researchers noted a sharp decline in the medium sized murines during the 60-50 ka age range. This decrease in species can be correlated to the paleoclimate record, which indicated a substantial decrease in available vegetation. As time progressed to the age range 47-12 ka, researchers noticed no significant change in body size. This was a surprise to the researchers due to the geologic record indicating high levels of volcanic activity. The next range, 12-5 ka, exhibited a decrease in overall murine size that can be attributed to the high rainfall and monsoon season recorded for this time period. Finally, the age range 5-3 ka, showed the first increase of medium sized murines which could be correlated to the dispersal of Homo floresiensis and the subsequent opening of habitats, but will need further research to support the claim.

Why is this study important? This study is important because it shows the relationship between the dominant non-human animals and Homo floresiensis within the Liang Bua cave. Additionally, the researchers explored other ecological factors (e.g, weather, resource availability, volcanic activity) and showed how it affects not only the fauna in general, but showed the difference in responses between sizes.

The big picture: The researchers set out to determine the ways in which the dominant fauna, second to the hominid species, responded throughout time with the introduction and dispersal Homo floresiensis. While there was a relationship noted between murine size/distribution and hominid involvement, the data also suggested that additional ecological factors may have contributed; therefore, no significant conclusions can be made without additional research regarding the true impact of Homo floresiensis. 

Citation: Veatch, E. G., Tocheri, M. W., Sutikna, T., McGrath, K., Saptomo, E. W., & Helgen, K. M. (2019). Temporal shifts in the distribution of murine rodent body size classes at Liang Bua (Flores, Indonesia) reveal new insights into the paleoecology of Homo floresiensis and associated fauna. Journal of human evolution, 130, 45-60. https://doi.org/10.1016/j.jhevol.2019.02.002

Triassic vegetation and climate evolution on the northern margin of Gondwana: a palynological study from Tulong, southern Xizang (Tibet), China

by: Jungang Peng, Jianguo Li, Sam M. Slater, Qianqi Zhanga, Huaicheng Zhu, Vivi Vajda

Summarized by: Kailey McCain

What data were used? Researchers noticed that while there was extensive research in North American and European paleobotany (i.e., plant fossils) from the Triassic period, data was very limited for Southern Asia. To fill this gap in knowledge, 147 samples were collected across China and examined for pollen, dust, and other microscopic fossils (also known as palynomorphs). Additionally, rock samples that dated through the Early Triassic were collected and processed. 

Methods: The samples were processed using hydrochloric acid (HCl is strong acid and has a low pH value ~1) and hydrofluoric acid (HF is a weak acid and has a higher pH value ~6) lab techniques. By using these acids, the microfossils were isolated from the sediment sample and placed on a microscope slide for further investigation. 

The palynology samples were tested for pollen and spores (cells that are capable of developing into a new individual without another reproductive cell). The abundance of specific species were then mapped to illustrate vegetation and climate during the Olenekian, a period of time during the Early Triassic. The identified microfossils can be seen in figure 1. 

Results: The data collected showed that there are roughly three vegetation stages throughout the Early Triassic. The first stage is dominated by pteridosperms (fern-like vegetation lacking spores), which indicated a warm and dry climate. The following stage exhibited a decrease in pteridosperms and an increase in conifers (woody plants). This change in vegetation indicates a decrease in temperature and an increase in humidity. The final stage exhibits a steady increase in conifers and a diverse range in ferns, thus indicating a stable and temperate climate.

Using these stages, researchers were then able to compare the shifts in vegetation and climate to the tectonic activity due to the rifting (splitting) of Gondwana, an ancient supercontinent that split from Pangea. Through the examination of the rifts and ocean levels, the researchers hypothesized that the separation of Gondwana was a driving factor in regional climate and vegetation shifts. 

Why is this study important? This study provided insights into the ways tectonic activity affected the environment in an area that lacked prior research. It drew important correlations between climate and tectonic activity. Additionally, evaluating the specific abundance and lack of certain vegetation helps establish evolutionary patterns not only in the Triassic, but also in supercontinents. 

The big picture: Paleobotany and palynological data paint a great picture of what Earth was like during certain time periods. Specifically, the data collected in this study shows a correlation in Triassic vegetation and climate evolution during the rifting of Gondwana in Southern Asia.

Citation: Triassic vegetation and climate evolution on the northern margin of Gondwana: a palynological study from Tulong, southern Xizang (Tibet), China. (2019). Journal of Asian Earth Sciences, 175, 74–82. https://doi.org/10.1016/j.jseaes.2018.06.005

An Interaction Between Climate Change and Infectious Disease Drove Widespread Amphibian Declines

by: Jeremy M. Cohen, David J. Civitello, Matthew D. Venesky, Taegan A. McMahon, Jason R. Rohr

Summarized by: Kailey McCain

What data were used? 

This study combined laboratory experiments, field data, and climate records together to support their hypothesis that amphibians have a higher mortality (death) rate when exposed to warmer temperatures, this is known as the “thermal mismatch hypothesis”

Methods: 

The laboratory experiments consisted of a temperature gradient and a temperature shift experiment. Both experiments exposed an endangered captive frog, Atelopus zeteki or the Panamanian Golden Frog, to a disease causing fungus, Batrachochytrium dendrobatidis, and measured the rate of death. The temperature gradient gradient slowly increased the temperature, while the temperature shift experiment exposed the frog to the fungus at specific temperature units: 14°C, 17°C, 23°C, or 26°C.  

The data was then compared to field data collected from the International Union for Conservation of Nature red list database to observe a real time decline in a total of 66 species of frog. The geographical range for the field data was limited to Latin America and the rate of decline was compared to historic monthly climate data.

Results:  

The results of the temperature gradient and temperature shift experiments show that mortality increased when the infected frog was exposed to higher temperatures. However, it also shows that temperature did not affect the mortality rate of the control group, the non infected frogs. As for the field data collected, the results showed that the frogs’ decline could not be correlated to precipitation nor altitude, but climate change, the thermal mismatch hypothesis clearly  predicted an increased decline of the species.

Why is this study important? 

This study tackles two of the largest challenges facing the modern world: climate change and disease prevalence. Some believe these issues are falsely linked, but the evidence collected in this study shows a positive correlation between disease induced death and increased temperature, both in a laboratory environment and the outside world. 

The big picture: 

While this study was isolated in geographical terms, the data collected gives researchers a look into what the future might hold for the spread of diseases in a warming world. Alone, the rising temperatures were not found to increase the rate of mortality; however, when mixed with a pathogen, a deadly combination was created and increased the rate of mortality greatly.

Citation: full citation of paper 

Cohen, J. M., Civitello, D. J., Venesky, M. D., McMahon, T. A., & Rohr, J. R. (2019). An interaction between climate change and infectious disease drove widespread amphibian declines. Global Change Biology, 3, 927. https://doi-org.ezproxy.lib.usf.edu/10.1111/gcb.14489