Migratory birds can be taught to adjust to climate change

One result of climate change is that spring is arriving earlier. However, migratory birds are not keeping up with these developments and arrive too late for the peak in food availability when it is time for breeding. By getting the birds to fly a little further north, researchers in Lund, Sweden, and the Netherlands have observed that these birds can give their chicks a better start in life.

Global warming is causing problems for birds in Sweden and elsewhere. Warmer springs mean that caterpillars hatch, grow and pupate earlier compared with just a few decades ago. This has consequences for birds that cannot eat caterpillars that have entered the pupal stage. Therefore, when the food supply runs out at an ever earlier time in the spring, more and more chicks starve during the breeding season. This is a big problem for migratory birds that spend winters in Africa, as they do not know how early spring arrives in Sweden. Could the problem be solved if the migratory birds simply came home and started breeding earlier?

"It seems that our non-migratory birds are doing this to a certain extent. But, of course, they are present and can feel how early spring will come. We thought that perhaps the migratory birds could fly further north until they find a place with suitable well-developed caterpillars," says Jan-Åke Nilsson, biology researcher at Lund University in Sweden.

To test this in practice, the researchers decided to help some Pied Flycatchers along the way. The biologists caught Pied Flycatchers that had arrived prior to breeding in the Netherlands. The birds were then driven during the night to Vombs Fure, an area of pine forest outside Lund in Skåne, where they were released. The peak of caterpillar availability in Skåne is about two weeks later than in the Netherlands -- a distance of around 600 kilometres that a Pied Flycatcher could cover in just two nights.

"The birds that were given a lift from the Netherlands to Skåne synchronised very well with the food peak! As they started to breed about 10 days earlier the "Swedish" Pied Flycatchers they had a dramatically better breeding success than the Swedish ones as well as a better success than the Pied Flycatchers that remained in the Netherlands," says Jan-Åke Nilsson.

In addition, it was shown that the chicks of the Dutch Pied Flycatchers that had received migration assistance did not stop in the Netherlands when they returned after their first spring migration. Instead, they continued on to the area of pine forest outside Lund where they were born. Furthermore, they arrived earlier than the Swedish Pied Flycatchers and thereby had more well-fed chicks at Vombs Fure the year after the researchers gave the Pied Flycatchers a helping hand to find Skåne.

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You say tomato, these scientists say evolutionary mystery

Biologists at the University of Massachusetts Amherst have found evidence for evolutionary "syndromes" -- sets of traits that occur together -- that help to explain how tomatoes first evolved their distinctive blend of color, sweetness, acidity and aroma. The research, represented by a pair of papers recently published in Plants People Planet and The American Journal of Botany, not only shines a light on how fruits evolve in the wild, but will also be valuable to crop-improvement efforts aimed at breeding more nutritious and appealing varieties of fruits.

"Have you ever held a fresh tomato in your hand and wondered why it looks good, smells good and tastes delicious?" asks Jacob Barnett, graduate student in organismic and evolutionary biology at UMass Amherst and the papers' lead author. It turns out that the juicy, red tomatoes with their unique flavor have a long and circuitous evolutionary history.

Barnett and his co-authors, including Ana Caicedo, professor of biology at UMass Amherst, turned to the relatives of our modern tomatoes, a group of several wild species growing in the western coast of South America, from Chile to Ecuador, to explore this question. And those wild species are nothing like what you'd find in your sandwich or salad today.

"For one thing, they're tiny," says Barnett, "about the size of a blueberry. And most of them are green when ripe. Many smell like apples, melons or even cucumbers, and a number of them taste terrible."

So how did we get from a tiny, green, terrible-tasting, melon-smelling fruit to the sublime blend of color, sweetness, acidity and umami that makes tomatoes so beloved in pasta sauces, salads and pizzas?

It turns out that fruits in the wild tend to have sets of traits that occur together, which biologists call syndromes. For example, many fruits are small, brightly colored and high in sugar. But evidence of evolutionary syndromes in wild tomatoes has been hard to gather, because no previous researchers had grown all the species of wild tomatoes together at the same time.

"These two studies are the first to look at fruit traits across all species in the entire tomato group," says Caicedo. "We have been able to tell a comprehensive story of how wild tomatoes compare to each other and to our modern, cultivated varieties."

Part of that story involves the collecting efforts of Charles Rick, from the University of California Davis, who traveled through South America in the 1950s and 1960s collecting seeds from wild species and bringing them back to what would become the C.M. Rick Tomato Genetics Resource Center. Barnett and Caicedo acquired seeds from 13 species of wild tomato, as well seeds from multiple variants within each species, and then grew them at the UMass Crop and Animal Research and Education Farm in South Deerfield, Massachusetts.

When mature, the plants were "wild and scraggly," says Caicedo, and at one point Barnett had to hack his way through them with a machete on his way to gathering their fruits and leaves. Back in the lab, the team scanned the fruits for color and shape, measured sugar and acid content and analyzed the DNA in the leaf samples. With the help of co-author Denise Tieman, research assistant professor at the University of Florida, Barnett measured and classified each sample's volatile organic compounds -- the chemicals responsible for tomatoes' smell.

Not only did the team discover that smell, flavor and color are syndromatic, they also discovered that there is what Barnett calls an "honest signal" -- a match between the outside appearance of the tomato and the inside nutritional content. This match supports a controversial hypothesis that animal preferences shaped the evolution of fruit syndromes, because animals will choose some fruits over others if they learn to associate the fruit's looks with its unique nutrient reward.

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Humans are unique but not exceptional species of mammal

In modern society, one parent may take a daughter to ballet class and fix dinner so the other parent can get to exercise class before picking up the son from soccer practice. To an observer, they seem to be cooperating in their very busy, co-parenting, monogamous relationship.

These people may think they are part of an evolved society different from the other mammals that inhabit earth. But their day-to-day behavior and child-rearing habits are not much different than other mammals who hunt, forage for food, and rear and teach their children, researchers suggest.

"For a long time it has been argued that humans are an exceptional, egalitarian species compared to other mammals," said Monique Borgerhoff Mulder, professor emerita of anthropology at the University of California, Davis, and corresponding author of a new study. But, she said, this exceptionalism may have been exaggerated.

"Humans appear to resemble mammals that live in monogamous partnerships and to some extent, those classified as cooperative breeders, where breeding individuals have to rely on the help of others to raise their offspring," she said.

The UC Davis-led study, with more than 100 researchers collaborating from several institutions throughout the world, is the first to look at whether human males are more egalitarian than are males among other mammals, focusing on the numbers of offspring they produce.

The article, "Reproductive inequality in humans and other mammals," was published this week (May 22) in the Proceedings of the National Academy of Sciences. Co-authors include researchers from UC Davis, The Santa Fe Institute, the National Institute for Mathematical and Biological Synthesis, and the Max Planck Institute for Evolutionary Anthropology, Germany.

The researchers amassed data from 90 human populations comprising 80,223 individuals from many parts of the world -- both historical and contemporary. They compared the records for men and women to lifetime data for 45 different nonhuman, free-ranging mammals.

The researchers found that humans are by no means exceptional, merely another unique species of mammal. Furthermore, as first author Cody Ross, former UC Davis graduate student in the Department of Anthropology now at the Max Planck Institute, points out "we can quite successfully model reproductive inequality in humans and nonhumans using the same predictors."

Egalitarianism in polygynous societies

Somewhat unexpectedly, when focusing specifically on women, the researchers found greater reproductive egalitarianism in societies that allow for polygynous marriage than in those where monogamous marriage prevails. In polygynous systems, in which men take several wives at the same time, women tend to have more equal access to resources, such as land, food and shelter -- and parenting help. This is because women, or their parents on their behalf, favor polygynous marriages with wealthy men who have more resources to share.

Researchers observed something else in their work.

"It turns out that monogamous mating (and marriage) can drive significant inequalities among women," Borgerhoff Mulder said. Monogamy, practiced in agricultural and market economies, can promote large differences in the number of children couples produce, researchers found, resulting from large differences in wealth in such economies.

How humans may differ

The fact men are relatively egalitarian compared to other animals reflects our patterns of child rearing. Human children are heavily dependent on the care and resources provided by both mothers and fathers -- a factor that is unusual, but not completely absent -- in other mammals, researchers said.

The critical importance of the complementary nature of this care -- that that each parent provides different and often non-substitutable resources and care throughout long human childhoods -- is why we don't show the huge reproductive variability seen in some of the great apes, said researcher Paul Hooper, from the University of New Mexico.

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Chicken breeding in Japan dates back to fourth century BCE

Conclusive evidence of chicken breeding in the Yayoi period of Japan has been discovered from the Karako-Kagi site.

The chicken is one of the most common domesticated animals, with a current estimated population of over 33 billion individuals. They are reared for their meat and eggs, and may be kept as pets.

The chicken is believed to have been domesticated in Southeast Asia about 3500 years ago, following which they were carried to all corners of the world. The exact date of introduction of chicken breeding to Japan is under debate, as there are no historical records and archeological evidence is inconclusive.

Professor Masaki Eda at the Hokkaido University Museum led a team to uncover the earliest conclusive evidence of chicken breeding in Japan. The findings, which show chickens were bred in the Karako-Kagi site, a settlement from the Yayoi period [5th century BCE to around 2nd century BCE], were published in the journal Frontiers in Earth Sciences.

"Chickens and their wild relatives belong to a family of birds called Phasianids, which includes pheasants, turkeys and quail," explains Eda. "Bones of juvenile phasianids recovered from archeological sites could not indisputably be identified as belonging to chickens or to similarly sized wild pheasants. Identification of juveniles is important, as it would indicate that breeding of chickens took place."

The Karako-Kagi site, in what is now Tawaramoto Town, Nara Prefecture, is considered to be a settlement that played the role of a leader of the Kinki region during the Yayoi period. There are multiple archeological digs in the area; one such dig, at the 58th research point, yielded ten phasianid bones, four of which belonged to juvenile birds.

The team used a technique called Zooarchaeology by Mass Spectrometry (ZooMS) to analyze the collagen in two of the juvenile phasianid bones. Previous work by Eda had shown that domestic chicken and Japanese wild pheasants had different ZooMS fingerprints; ZooMS revealed that both the two bones belonged to chickens. The collagen from one of the bones was also carbon dated to 381-204 BCE, corresponding to the middle Yayoi period.

"Ten of the eleven previously-discovered bones of adult chickens from this period have all belonged to males; hence, it was thought chicken breeding could not have occurred on the Japanese archipelago," Eda elaborated. "By identifying bones from juvenile chickens, we provide clear evidence that breeding did occur in that time period -- which is also the earliest time chickens could have been introduced to Japan. In addition, Karako-Kagi is considered an important trade hub of the Yayoi period, so there is a possibility that this status is a factor in chicken breeding during the period."

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On a warming planet, these Arctic geese rapidly found (and shared) a new migratory route

As the planet warms, animals that breed in the Arctic are at particular risk. But a new study reported in Current Biology on March 1 offers some encouraging news: in an apparent reaction to pressures along their former migratory route, a population of Arctic geese has rapidly adjusted, forming a new migration route and breeding location almost 1,000 kilometers from their original stomping grounds.

What's more, it appears the new route has caught on with other geese and even birds of other species via cultural transmission (social learning). As such, the new population already has grown to as many as 4,000 individuals.

"It is extremely fascinating to witness such rapid evolution of new breeding grounds and migratory route by a bird species that is regarded as being very traditional in its behavior and site use," said Jesper Madsen of Aarhus University in Denmark. "It gives some hope for 'ecological rescue' at times of very radical environmental changes due to climate change and, more broadly, global change."

"We observe a new distinct population of birds in the making in real time," he added. "This is very rare to observe. The speed of the development is astonishing."

Madsen's team has been studying Norway's Svalbard population of pink-footed geese for more than 35 years. They've kept tabs on their population size and demographic variables, using a systematic marking and resighting program. About 20 years ago, they started getting reports of geese turning up on migration in Sweden and Finland, which were confirmed as members of the Svalbard population.

To learn more, Madsen went to Oulu, Finland, in the spring of 2018 and 2019 with his goose-catching team from Denmark as well as Dutch and Finnish partners. Their hope was to catch and tag some pink-footed geese with GPS tags. They wanted to know where these geese were going, and they got an unexpected answer.

"It was a real surprise to see that half of the marked individuals in Oulu migrated northeast to Novaya Zemlya in north Russia," Madsen says. "From the tagging information we could not only follow their new path but also got indications that females were breeding there. This site is around 1,000 kilometers east of the Svalbard breeding grounds.

"It was also cool to observe that geese from the traditional flyway have turned up on the new route and seemed to have switched. Hence, social learning and following individuals from the new route has been an important phenomenon, which also explains how this development could be so fast."

With their new report, they've now documented an abrupt formation of a new migration route and population for the Arctic geese over the course of 10 to 15 years. The population has grown over time due to successful breeding and high survival rates combined with continued immigration of geese from the old route to the new one.

Their ability to live in Novaya Zemlya has apparently been aided by warming in the area, they say. While the new population is not genetically or demographically isolated yet, they note that it already now qualifies as a separate population.

The new route does have some disadvantages, Madsen says. For instance, it's longer. But they suspect the benefits of the new route and grounds outweigh any downsides. The findings in geese show the importance of social learning on a changing planet, Madsen notes, especially in social animals including birds but perhaps also hoofed ungulates, wolves, and whales.

"At this time, when climate change and other human activities threaten many species, not least the Arctic ones, social learning can be a behavior that can provide advantages to avoid some negative impacts, at least in the short term," Madsen says.

The researchers say they hope one day to observe the geese in their new breeding grounds in Russia. For now, they'll keep an eye on the future development of the new population using GPS-tracking devices and remote sensing of the new environment.

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Rice breeding breakthrough to feed billions

An international team has succeeded in propagating a commercial hybrid rice strain as a clone through seeds with 95 percent efficiency. This could lower the cost of hybrid rice seed, making high-yielding, disease resistant rice strains available to low-income farmers worldwide. The work was published Dec. 27 in Nature Communications.

First-generation hybrids of crop plants often show higher performance than their parent strains, a phenomenon called hybrid vigor. But this does not persist if the hybrids are bred together for a second generation. So when farmers want to use high-performing hybrid plant varieties, they need to purchase new seed each season.

Rice, the staple crop for half the world's population, is relatively costly to breed as a hybrid for a yield improvement of about 10 percent. This means that the benefits of rice hybrids have yet to reach many of the world's farmers, said Gurdev Khush, adjunct professor emeritus in the Department of Plant Sciences at the University of California, Davis. Working at the International Rice Research Institute from 1967 until retiring to UC Davis in 2002, Khush led efforts to create new rice high-yield rice varieties, work for which he received the World Food Prize in 1996.

One solution to this would be to propagate hybrids as clones that would remain identical from generation to generation without further breeding. Many wild plants can produce seeds that are clones of themselves, a process called apomixis.

"Once you have the hybrid, if you can induce apomixis, then you can plant it every year," Khush said.

However, transferring apomixis to a major crop plant has proved difficult to achieve.

One Step to Cloned Hybrid Seeds

In 2019, a team led by Professor Venkatesan Sundaresan and Assistant Professor Imtiyaz Khanday at the UC Davis Departments of Plant Biology and Plant Sciences achieved apomixis in rice plants, with about 30 percent of seeds being clones.

Sundaresan, Khanday and colleagues in France, Germany and Ghana have now achieved a clonal efficiency of 95 percent, using a commercial hybrid rice strain, and shown that the process could be sustained for at least three generations.

The single-step process involves modifying three genes called MiMe which cause the plant to switch from meioisis, the process that plants use to form egg cells, to mitosis, in which a cell divides into two copies of itself. Another gene modification induces apomixis. The result is a seed that can grow into a plant genetically identical to its parent.

The method would allow seed companies to produce hybrid seeds more rapidly and at larger scale, as well as providing seed that farmers could save and replant from season to season, Khush said.

"Apomixis in crop plants has been the target of worldwide research for over 30 years, because it can make hybrid seed production can become accessible to everyone," Sundaresan said. "The resulting increase in yields can help meet global needs of an increasing population without having to increase use of land, water and fertilizers to unsustainable levels."

The results could be applied to other food crops, Sundaresan said. In particular, rice is a genetic model for other cereal crops including maize and wheat, that together constitute major food staples for the world.

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Elephant seal’s map sense tells them when to head ‘home’

Each year, pregnant female elephant seals take an approximately 240-day trek over 10,000 kilometers across the Eastern North Pacific Ocean before returning to their breeding beaches to give birth within five days of their arrival. Now, a study appearing February 28 in the journal biology Current Biology finds that this impressive navigation ability depends on an internal map sense, which functions much like a built-in GPS.

"We found that migrating elephant seals know how far they are from their breeding beach thousands of kilometers away," said Roxanne Beltran of the University of California Santa Cruz. "They also know approximately how long it will take them to get back."

Beltran and her colleagues, including Dan Costa, knew that elephant seals are expert navigators. What they didn't know was how the seals manage to make it back to the beach just in time for the breeding season.

In the new study, the researchers used satellite tracking data collected from more than 100 adult female seals. They figured out when each of them turned around to head back to the beach where they started from.

The data revealed that seals decided to turn around based strongly on how far away they were from where they needed to go. Their decisions to turn around weren't related to their body condition, measured as amount of body fat.

"We were surprised that foraging success or percent body fat was not more strongly related to when seals begin the return portion of the migration," Beltran said. "We expected that highly successful (i.e. fatter) seals might end their foraging trips earlier, but that was not the case; instead, it seems like they are well programmed to turn around strategically based on where they are and in turn how long it will take them to get back."

The researchers don't yet know what sensory cues the elephant seals depend on to keep track of where they are and head in the right direction at the right time, but it's clear that they can adjust the timing of their travels based on an internal perception of time and space.

The results help to better understand elephant seals, with important implications for their conservation, the researchers say. In future studies, they hope to quantify exactly how precise the seals' navigation ability is and determine which cues are most important.

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World's largest fish breeding area discovered in Antarctica

Near the Filchner Ice Shelf in the south of the Antarctic Weddell Sea, a research team has found the world's largest fish breeding area known to date. A towed camera system photographed and filmed thousands of nests of icefish of the species Neopagetopsis ionah on the seabed. The density of the nests and the size of the entire breeding area suggest a total number of about 60 million icefish breeding at the time of observation. These findings provide support for the establishment of a Marine Protected Area in the Atlantic sector of the Southern Ocean. A team led by Autun Purser from the Alfred Wegener Institute publish their results in the current issue of the scientific journal Current Biology.

The joy was great when, in February 2021, researchers viewed numerous fish nests on the monitors aboard the German research vessel Polarstern, which their towed camera system transmitted live to the vessel from the seabed, 535 to 420 metres below the ship, from the seafloor of the Antarctic Weddell Sea. The longer the mission lasted, the more the excitement grew, finally ending in disbelief: nest followed nest, with later precise evaluation showing that there were on average one breeding site per three square metres, with the team even finding a maximum of one to two active nests per square metre.

The mapping of the area suggests a total extent of 240 square kilometres, which is roughly the size of the island of Malta. Extrapolated to this area size, the total number of fish nests was estimated to be about 60 million. "The idea that such a huge breeding area of icefish in the Weddell Sea was previously undiscovered is totally fascinating," says Autun Purser, deep-sea biologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and lead author of the current publication. After all, the Alfred Wegener Institute has been exploring the area with its icebreaker Polarstern since the early 1980s. So far, only individual Neopagetopsis ionah or small clusters of nests have been detected here.

The unique observations are made with a so-called OFOBS, the Ocean Floor Observation and Bathymetry System. It is a camera sledge built to survey the seafloor of extreme environments, like ice-covered seas. It is towed on a special fibre-optic and power cable normally at a speed of about one half to one knot, about one and half metres above the seafloor. "After the spectacular discovery of the many fish nests, we thought about a strategy on board to find out how large the breeding area was -- there was literally no end in sight. The nests are three quarters of a metre in diameter -- so they are much larger than the structures and creatures, some of which are only centimetres in size, that we normally detect with the OFOBS system," Autun Purser reports. "So, we were able to increase the height above ground to about three metres and the towing speed to a maximum of three knots, thus multiplying the area investigated. We covered an area of 45,600 square metres and counted an incredible 16,160 fish nests on the photo and video footage," says the AWI expert.

Based on the images, the team was able to clearly identify the round fish nests, about 15 centimetres deep and 75 centimetres in diameter, which were made distinct from the otherwise muddy seabed by a round central area of small stones. Several types of fish nests were distinguished: "Active" nests, containing between 1,500 and 2,500 eggs and guarded in three-quarters of the cases by an adult icefish of the species Neopagetopsis ionah, or nests which contained only eggs; there were also unused nests, in the vicinity of which either only a fish without eggs could be seen, or a dead fish. The researchers mapped the distribution and density of the nests using OFOBS's longer-range but lower-resolution side scan sonars, which recorded over 100,000 nests.

The scientists combined their results with oceanographic and biological data. The result: the breeding area corresponds spatially with the inflow of warmer deep water from the Weddell Sea onto the higher shelf. With the help of transmitter equipped seals, the multidisciplinary team was also able to prove that the region is also a popular destination for Weddell seals. 90 per cent of the seals' diving activities took place within the region of active fish nests, where they presumably go in search of food. No wonder, the researchers calculate the biomass of the ice fish colony there at 60 thousand tonnes.

With its biomass, this huge breeding area is an extremely important ecosystem for the Weddell Sea and, according to current research, likely to be the most spatially extensive contiguous fish breeding colony discovered worldwide to date, the experts report in the publication in Current Biology.

German Federal Research Minister Bettina Stark-Watzinger said: "My congratulations to the researchers involved on their fascinating discovery. After the MOSAiC expedition, German marine and polar research has once more reaffirmed its outstanding position. German research vessels are floating environmental research laboratories. They continue to sail the polar seas and our oceans almost non-stop, serving as platforms for science aimed at generating important findings to support climate and environmental protection. Funding by the Federal Ministry of Education and Research (BMBF) provides German marine and polar research with one of the most state-of-the-art research vessel fleets worldwide. This discovery can make an important contribution towards protecting the Antarctic environment. The BMBF will continue to work towards this goal under the umbrella of the United Nations Decade of Ocean Science for Sustainable Development that runs until 2030."

For AWI Director and deep-sea biologist Prof. Antje Boetius, the current study is a sign of how urgent it is to establish marine protected areas in Antarctica. "This great discovery was enabled by a specific under-ice survey technology we developed during my ERC Grant. It shows how important it is to be able to investigate unknown ecosystems before we disturb them. Considering how little known the Antarctic Weddell Sea is, this underlines all the more the need of international efforts to establish a Marine Protected Area (MPA)," Antje Boetius classifies the results of the study, in which she was not directly involved. A proposal for such an MPA has been prepared under the lead of the Alfred Wegener Institute and is defended since 2016 by the European Union and its member states as well as other supporting countries in the international Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

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Most dog breeds highly inbred

Dog breeds are often recognized for distinctive traits -- the short legs of a dachshund, wrinkled face of a pug, spotted coat of a Dalmatian. Unfortunately, the genetics that give various breeds their particular attributes are often the result of inbreeding.

In a recent study published in Canine Medicine and Genetics, an international team of researchers led by University of California, Davis, veterinary geneticist Danika Bannasch show that the majority of canine breeds are highly inbred, contributing to an increase in disease and health care costs throughout their lifespan.

"It's amazing how inbreeding seems to matter to health," Bannasch said. "While previous studies have shown that small dogs live longer than large dogs, no one had previously reported on morbidity, or the presence of disease. This study revealed that if dogs are of smaller size and not inbred, they are much healthier than larger dogs with high inbreeding."

Inbreeding affects health

The average inbreeding based on genetic analysis across 227 breeds was close to 25%, or the equivalent of sharing the same genetic material with a full sibling. These are levels considered well above what would be safe for either humans or wild animal populations. In humans, high levels of inbreeding (3-6%) have been associated with increased prevalence of complex diseases as well as other conditions.

"Data from other species, combined with strong breed predispositions to complex diseases like cancer and autoimmune diseases, highlight the relevance of high inbreeding in dogs to their health," said Bannasch, who also serves as the Maxine Adler Endowed Chair in Genetics at the UC Davis School of Veterinary Medicine.

The researchers partnered with Wisdom Health Genetics, a world leader in pet genetics, to obtain the largest sample size possible for analysis. Wisdom Health's database is the largest dog DNA database in the world, helping researchers collect data from 49,378 dogs across 227 breeds -- primarily from European sources.

Some breeds more inbred

So, what makes a dog breed more inbred than others? Bannasch explained that it's often a combination of a small founding population followed by strong selection for particular traits in a breed -- often based on looks rather than purpose. While she has always had an interest in the population structure of some of these breeds, she became particularly interested in the Danish-Swedish farmdog several years ago. She fell in love with their compact size, disposition and intelligence, and ended up importing one from Sweden.

Bannasch discovered that Danish-Swedish farmdogs have a low level of inbreeding based on their history of a relatively large founding population of 200, and being bred for function, rather than a strong artificial selection for looks. And according to the insurance health data on breeds collected from Agria Insurance Sweden and hosted online by the International Partnership for Dogs, the farmdog is one of the healthiest breeds.

The study also revealed a significant difference in morbidity between brachycephalic (short skull and snout) and non-brachycephalic breeds. While that finding wasn't unexpected, the researchers removed brachycephalic breeds from the final analysis on effects of inbreeding on health.

Preserving genetic diversity

In the end, Bannasch said she isn't sure there is a way out of inbred breeds. People have recognized that creating matches based solely on pedigrees is misleading. The inbreeding calculators don't go back far enough in a dog's genetic line, and that method doesn't improve overall high levels of population inbreeding.

There are other measures that can be taken to preserve the genetic diversity and health of a breed, she said. They include careful management of breeding populations to avoid additional loss of existing genetic diversity, through breeder education and monitoring of inbreeding levels enabled by direct genotyping technologies.

Outcrosses are being proposed or have already been carried out for some breeds and conditions as a measure to increase genetic diversity, but care must be taken to consider if these will effectively increase overall breed diversity and therefore reduce inbreeding, Bannasch said. In particular, in the few breeds with low inbreeding levels, every effort should be made to maintain the genetic diversity that is present.

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Breeding plants with genes from one parent

Scientists are a step closer to breeding plants with genes from only one parent. New research led by plant biologists at the University of California, Davis, published Nov. 19 in Science Advances, shows the underlying mechanism behind eliminating half the genome and could make for easier and more rapid breeding of crop plants with desirable traits such as disease resistance.

The work stems from a discovery made over a decade ago by the late Simon Chan, associate professor of plant biology in the UC Davis College of Biological Sciences, and colleagues.

Plants, like other sexual organisms, inherit a matching set of chromosomes from each parent. In order to transmit a favorable trait, such as pest or drought resistance, to all their offspring, the plant would have to carry the same genetic variant on each chromosome. But creating plants that "breed true" in this way can take generations of cross-breeding.

In 2010, Chan and postdoctoral fellow Ravi Maruthachalam serendipitously discovered a way to eliminate the genetic contribution from one parent while breeding the lab plant Arabidopsis. They had modified a protein called CENH3, found in the centromere, a structure in the center of a chromosome. When they tried to cross wildtype Arabidopsiswith plants with modified CENH3, they got plants with half the normal number of chromosomes. The part of the genome from one parent plant had been eliminated to create a haploid plant.

That work was published in Nature in March 2010, setting off efforts to achieve the same result in crop plants such as maize, wheat and tomato.

Clearing up a mystery

But replicating Chan's exact strategy outside Arabidopsis has so far proved fruitless, said Professor Luca Comai, UC Davis Department of Plant Biology and Genome Center, who is senior author on the new paper. Recently, other labs have created plants with one set of chromosomes by manipulating CENH3, but it's not clear how the results are related.

"The mechanistic basis of CENH3 effects on haploid induction was mysterious," Comai said. There appear to be different rules for each species, he said.

Much of that mystery has now been cleared up. Mohan Marimuthu, researcher at the UC Davis Genome Center and Department of Plant Biology, with Comai, Maruthachalam (now at the Indian Institute of Science Education and Research, Kerala) and colleagues found that when CENH3 protein is altered, it is removed from the DNA in the egg before fertilization, weakening the centromere.

"In the subsequent embryonic divisions, the CENH3-depleted centromeres contributed by the egg fail to compete with the CENH3-rich ones contributed by the sperm and the female genome is eliminated," Comai said.

The finding that any selective depletion of CENH3 engenders centromere weakness explains the original results by Chan and Maruthachalam as well as new results from other labs in wheat and maize, Comai said. This new knowledge should make it easier to induce haploids in crop plants, he said.

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