Tag: Biology

Research based on a comprehensive study of 8,000 birds in Israel

Tel Aviv University (TAU) researchers say that climate change may be responsible for changes in the morphology of many birds in Israel over the past 70 years. The body mass of some species decreased while in others body length increased, in both cases increasing the ratio between surface area and volume. The researchers contend that these are strategies to facilitate heat loss to the environment.

“The birds evidently changed in response to the changing climate,” the researchers concluded. “However, this solution may not be fully adequate, especially as temperatures continue to rise.”

The study was led by Professor Shai Meiri and PhD student Shahar Dubiner of the School of Zoology, Wise Faculty of Life Sciences, and the Steinhardt Museum of Natural History at TAU. The paper was published in the scientific journal Global Ecology and Biogeography.

Professor Meiri explains that according to “Bergmann’s rule,” an ecogeographical rule formulated in the 19th century, members of bird and mammal species living in a cold climate tend to be larger than members of the same species living in a warmer climate. This is because the ratio of surface area to volume is higher in smaller animals, permitting more heat loss (an advantage in warm regions), and lower in larger bodies, minimizing heat loss (a benefit in colder climates). Based on this rule, scientists have predicted that global warming will lead to a reduction in animal size, with a possible exception: birds living in the human environment (such as pigeons, house sparrows, and the hooded crow) may gain size due to increased food availability, a phenomenon already witnessed in mammals such as jackals and wolves.

Relying on the vast bird collection preserved by the Steinhardt Museum of Natural History at TAU, the researchers looked for changes in bird morphology over the past 70 years in Israel. They examined approximately 8,000 adult specimens of 106 different species, including migratory birds that annually pass through Israel such as the common chiffchaff, white stork, and black buzzard; resident wild birds like the Eurasian jay, Eurasian eagle-owl, and rock partridge; and commensal birds that live near humans. They built a complex statistical model consisting of various parameters to assess morphological changes — in the birds’ body mass, body length and wing length — during the relevant period.

“Our findings revealed a complicated picture,” Dubiner says. “We identified two different types of morphological changes: some species had become lighter – their mass had decreased while their body length remained unchanged; while others had become longer – their body length had increased, while their mass remained unchanged. These together represent more than half of the species examined, but there was practically no overlap between the two groups – almost none of the birds had become both lighter and longer.

“We think that these are two different strategies for coping with the same problem, namely the rising temperatures. In both cases, the surface area to volume ratio is increased by either increasing the numerator or reducing the denominator, which helps the body lose heat to its environment. The opposite, namely a decrease in this ratio, was not observed in any of the species.”

These findings were observed across the country, regardless of nutrition, and in all types of species. A difference was identified, however, between the two strategies: changes in body length tended to occur more in migrants, while changes in body mass were more typical of non-migratory birds. The very fact that such changes were found in migratory birds coming from Asia, Europe, and Africa suggests that this is a global phenomenon. The study also found that the impact of climate change over time on bird morphology is 10 times greater than the impact of similar differences in temperature between geographical areas.

“Our findings indicate that global warming causes fast and significant changes in bird morphology,” Dubiner concludes. “But what are the implications of these changes? Should we be concerned? Is this a problem, or rather an encouraging ability to adapt to a changing environment? Such morphological changes over a few decades probably do not represent an evolutionary adaptation, but rather certain phenotypic flexibility exhibited by the birds. We are concerned that over such a short period of time, there is a limit to the flexibility or evolutionary potential of these traits, and the birds might run out of effective solutions as temperatures continue to rise.”

Inventive Study to Develop Biological Solutions for Agriculture

TAU and ag-biotech company PlantArcBio to collaborate on development of RNAi-based products.

Genetically improved plants can be a real-life magic stick for solving global famine issues. In a first-of-its-kind study, Ramot, the Technology Transfer Company of Tel Aviv University will cooperate with ag-biotech company PlantArcBio to develop innovative RNAi-based biological solutions for agriculture.

RNAi technology enables a temporary external disruption of RNA (ribonucleic acid) molecules, diminishing the amount of Messenger RNA (mRNA), thus temporarily reducing the expression of specific genes, without modifying or genetically engineering the organism’s DNA. Externally applied RNAi molecules affect specific genes for a specific time period, as required for positive effects like crop protection and yield enhancement. 

Specifically, the research will focus on testing the joint technology’s contribution to the stability of RNAi-based products and their ability to penetrate plants and insects.

Joining Forces

The first-of-its-kind joint study will examine the efficacy of PlantArcBio‘s RNAi technology for agriculture, combined with the unique lipid-based RNA delivery technology developed by Prof. Dan Peer, TAU’s Vice President for R&D, head of the Center for Translational Medicine and a member of both the Shmunis School of Biomedicine and Cancer ResearchGeorge S. Wise Faculty of Life Sciences, and the Center for Nanoscience and Nanotechnology, and a pioneer using RNA to manipulate cells in cancer and other immune related diseases.  


Prof. Dan Peer

“We see great value in contributing to the development of RNAi-based products addressing global issues and providing an ecological and environmentally friendly solution to the global challenges of sustainability in agriculture and food security,” says Peer.

Keren Primor Cohen, CEO of Ramot, believes there is “extensive commercial potential for this combined technology” and welcomes the collaboration with PlantArcBio.

The research will be carried out both at PlantArcBio‘s Laboratories and at Prof. Dan Peer’s Laboratory of Precision NanoMedicine at Tel Aviv University. According to Dror Shalitin, Founder and CEO of PlantArcBio, the results are expected within approximately 12 months.

Tiny insects become “visible” to bats when they swarm

3-D simulations could provide new insights into the evolution of bat echolocation, TAU researchers say

Bats use echolocation to hunt insects, many of which fly in swarms. In this process, bats emit a sound signal that bounces off the target object, revealing its location. Smaller insects like mosquitos are individually hard to detect through echolocation, but a new Tel Aviv University study reveals that they become perceptible when they gather in large swarms. The findings could provide new insights into the evolution of bat echolocation and explain why tiny insects are found in the diets of bats that seem to use sound frequencies that are too high to effectively detect them. The new research was conducted by Dr. Arjan Boonman and Prof. Yossi Yovel at TAU’s Department of Zoology and colleagues at Canada’s Western University. It was published in PLOS Computational Biology on December 12.

Modeling bat vision

Few studies have addressed what swarms of insects — as opposed to single insects — “look” like to bats. To find out, Dr. Boonman and colleagues combined three-dimensional computer simulations of insect swarms with real-world measurements of bat echolocation signals to examine how bats sense swarms that vary in size and density. They found that small insects that are undetectable on their own, such as mosquitos, suddenly become “visible” to bats when they gather in large swarms. They also discovered that the fact that bats use signals with multiple frequencies is well suited to the task of detecting insect swarms. These signals appear to be ideal for detecting an object if more than one target falls inside the echolocation signal beam at once. “Using simulations, we investigated something that could never have been measured in reality,” Dr. Boonman says. “Modeling enabled us to have full control over any aspect of an insect swarm, even the full elimination of the shape of each insect within the swarm.”

From insects to drones

The insect model the researchers used has a tiny mesh (skeleton) and minuscule legs and wings. “We are still adding new features, such as the bat’s acoustic beam or ears, which were not in the original model,” says Prof. Yovel. “We also developed a faster version of the algorithm. All of this will open a new world for us in which we can get echoes even from entire landscapes, so we can learn what a bat or sonar-robot would ‘see’ much more quickly.” The study could also affect technology being developed to improve defense systems. “The algorithms developed for this study could potentially be applied to radar echoes of drone swarms in order to lower the probability of detection by enemy radar,” Dr. Boonman explains. “Since drones are playing an ever more prominent role in warfare, our biological study could spawn new ideas for the defense industry.”


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