Like father, not like son

The song of songbirds is a learned, complex behavior and subject to strong selective forces. However, it is difficult to tease apart the influence of the genetic background and the environment on the expression of individual variation in song. Scientists from the Max Planck Institute for Ornithology in Seewiesen in collaboration with international researchers now compared song and brain structure of parents and offspring in zebra finches that have been raised either with their genetic or foster parents. They also varied the amount of food during breeding. Remarkably, both song and the underlying brain structure had a low heritability and were strongly influenced by environmental factors.

A central topic in behavioral biology is the question, which aspects of a behavior are learned or expressed due to genetic predisposition. Today it is known that our personality and behavior are far less determined by the genetic background. Especially during development environmental factors can shape brain and behavior via so-called epigenetic effects. Thereby hormones play an important role. A shift in hormone concentrations in early life can have long lasting effects for an organism, whereas the same change in adults often may show only short-term changes. However, whether the influence of the environment has either strong or weak effects can largely depend on the individual genetic predisposition. However, it is relatively hard to discriminate the effects of the environment from that of the genes.

An attempt to tease apart these effects has been conducted by researchers from the Max Planck Institute for Ornithology in collaboration with an international team of scientists in zebra finch breeding pairs. Using partial cross-fostering the researchers exchanged half of the eggs within a nest making them to “cuckoo’s eggs”. Therefore half of the hatchlings were raised by their genetic parents, whereas the other half was raised by their foster parents. In addition they modified the availability of food by mixing the seeds with husks so that the parents had to spend more time searching for food. When the male offspring were adult at 100 days the researchers recorded their songs and analyzed the underlying neuroanatomy. This partial cross-fostering design enabled the researchers to tease apart the involvement of genotype, the rearing environment and nutritional effects to variation in song behavior and brain structure.

The results showed that heritability values were low for most song characteristics, except the number of song syllables and maximum frequency. On the other hand the common rearing environment including the song of the foster father mainly predicted the proportion of unique syllables in the songs of the sons, moreover this relationship was dependent on food availability. Even more striking results were found when the researchers investigated the brain anatomy. Heritability of brain variables was very low and strongly controlled by the environment. For example, an emergence of a clear relationship between brain mass and genotype is prevented by varying environmental quality.

This result was quite surprising as previous studies have found a high heritability of the song control system in the songbird brain, however these studies did not account for variation of the rearing environment. ”Being highly flexible in response to environmental conditions can maintain genetic variation and influences song learning and brain development” says Stefan Leitner, senior author of the study.

Malign environmental combination favours schizophrenia

The interplay between an infection during pregnancy and stress in puberty plays a key role in the development of schizophrenia, as behaviourists from ETH Zurich demonstrate in a mouse model. However, there is no need to panic.

Around one per cent of the population suffers from schizophrenia, a serious mental disorder that usually does not develop until adulthood and is incurable. Psychiatrists and neuroscientists have long suspected that adverse enviromental factors may play an important role in the development of schizophrenia. Prenatal infections such as toxoplasmosis or influenza, psychological, stress or family history have all come into question as risk factors. Nevertheless, until now researchers were unable to identify the interplay of the individual factors linked to this serious mental disease.

However, a research group headed by Urs Meyer, a senior scientist at the Laboratory of Physiology & Behaviour at ETH Zurich, has now made a breakthrough: for the first time, they were able to find clear evidence that the combination of two environmental factors contributes significantly to the development of schizophrenia-relevant brain changes and at which stages in a person’s life they need to come into play for the disorder to break out. The researchers developed a special mouse model, with which they were able to simulate the processes in humans virtually in fast forward. The study has just been published in the journal Science.

Pesticides and Parkinson’s: UCLA researchers uncover further proof of a link

For several years, neurologists at UCLA have been building a case that a link exists between pesticides and Parkinson’s disease. To date, paraquat, maneb and ziram — common chemicals sprayed in California’s Central Valley and elsewhere — have been tied to increases in the disease, not only among farmworkers but in individuals who simply lived or worked near fields and likely inhaled drifting particles.

Now, UCLA researchers have discovered a link between Parkinson’s and another pesticide, benomyl, whose toxicological effects still linger some 10 years after the chemical was banned by the U.S. Environmental Protection Agency.

Even more significantly, the research suggests that the damaging series of events set in motion by benomyl may also occur in people with Parkinson’s disease who were never exposed to the pesticide, according to Jeff Bronstein, senior author of the study and a professor of neurology at UCLA, and his colleagues.

Benomyl exposure, they say, starts a cascade of cellular events that may lead to Parkinson’s. The pesticide prevents an enzyme called ALDH (aldehyde dehydrogenase) from keeping a lid on DOPAL, a toxin that naturally occurs in the brain. When left unchecked by ALDH, DOPAL accumulates, damages neurons and increases an individual’s risk of developing Parkinson’s.

The investigators believe their findings concerning benomyl may be generalized to all Parkinson’s patients. Developing new drugs to protect ALDH activity, they say, may eventually help slow the progression of the disease, whether or not an individual has been exposed to pesticides.

The research is published in the current online edition of Proceedings of the National Academy of Sciences.

Insects change the way they communicate when drowned out by man-made noises

Birds and frogs do it, even whales have been known to do it. Now scientists have for the first time shown that insects also change the way they sing to one another when drowned out by man-made noises.

Click HERE to listen to a grasshopper battling traffic noise

Grasshoppers living next to a main road respond to the increased background volume of passing traffic by adjusting their summer courtship songs, scientists have discovered.

In order to make themselves heard above the low-rumble noise pollution of moving vehicles, male bow-winged grasshoppers of central Europe alter the pitch of their songs’ lower notes so that they rise to a mini-crescendo, the scientists found.

“Bow-winged grasshoppers produce songs that include low and high frequency components,” said Ulrike Lampe of the University of Bielefeld in Germany, who led the study published in the journal Functional Ecology.

“We found that grasshoppers from noisy habitats boost the volume of the lower-frequency part of their song, which makes sense since road noise can mask signals in this part of the frequency spectrum,” Dr Lampe said.

University of Toronto study demonstrates impact of adversity on early life development

It is time to put the nature versus nurture debate to rest and embrace growing evidence that it is the interaction between biology and environment in early life that influences human development, according to a series of studies recently published in a special edition of the Proceedings of the National Academy of Sciences (PNAS).

"Biologists used to think that our differences are pre-programmed in our genes, while psychologists argued that babies are born with a blank slate and their experience writes on it to shape them into the adults they become. Instead, the important question to be asking is, ‘How is our experience in early life getting embedded in our biology?’" says University of Toronto behavioural geneticist Marla Sokolowski. She is co-editor of the PNAS special edition titled "Biological Embedding of Early Social Adversity: From Fruit Flies to Kindergarteners" along with professors Tom Boyce (University of British Columbia) and Gene Robinson (University of Illinois).

Sokolowski, who is a University Professor in the Department of Ecology & Evolutionary Biology (EEB), the inaugural academic director of Uof T’s Fraser Mustard Institute for Human Development and co-director of the Experience-based Brain and Biological Development Program (EBBD) at the Canadian Institute for Advanced Research (CIFAR) says that relatively little is known about the gene-environment interplay that underlies the impact of early life adversity on adult health and behaviour.

In one of the studies in the series, Sokolowski and her colleagues found that chronic food deprivation and lack of adequate nutrition in the early life of the fruit fly Drosophila melanogaster had significant impact on adult behaviour and quality of life. Fruit flies are especially useful for genetic studies because they share a surprising number of qualities with humans, are inexpensive to care for and reproduce rapidly, allowing for several generations to be studied in just a few months.

New studies reveal connections between animals’ microbial communities and behavior

New research is revealing surprising connections between animal microbiomes—the communities of microbes that live inside animals’ bodies—and animal behavior, according to a paper by University of Georgia ecologist Vanessa O. Ezenwa and her colleagues. The article, just published in the Perspectives section of the journal Science, reviews recent developments in this emerging research area and offers questions for future investigation.

The paper grew out of a National Science Foundation-sponsored workshop on new ways to approach the study of animal behavior. Ezenwa, an associate professor in the UGA Odum School of Ecology and College of Veterinary Medicine department of infectious diseases, and her coauthors were interested in the relationship between animal behavior and beneficial microbes.

Most research on the interactions between microbes and their animal hosts has focused on pathogens, Ezenwa said. Less is known about beneficial microbes or animal microbiomes, but several recent studies have begun to explore these connections.

"We know that animal behavior plays a critical role in establishing microbiomes," she said. "Once they’re established, the microbiomes then influence animal behavior in lots of ways that have far-reaching consequences. That’s what we were trying to highlight in this article."

(Image credit: sankax)

The collapse of the Fukushima Dai-ichi Nuclear Power Plant caused a massive release of radioactive materials to the environment. A prompt and reliable system for evaluating the biological impacts of this accident on animals has not been available. Here we show that the accident caused physiological and genetic damage to the pale grass blue Zizeeria maha, a common lycaenid butterfly in Japan. We collected the first-voltine adults in the Fukushima area in May 2011, some of which showed relatively mild abnormalities. The F₁ offspring from the first-voltine females showed more severe abnormalities, which were inherited by the F₂ generation. Adult butterflies collected in September 2011 showed more severe abnormalities than those collected in May. Similar abnormalities were experimentally reproduced in individuals from a non-contaminated area by external and internal low-dose exposures. We conclude that artificial radionuclides from the Fukushima Nuclear Power Plant caused physiological and genetic damage to this species.