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Wolves in the panhandle of southeast Alaska are currently being considered as an endangered species by the US Fish and Wildlife Service in response to a petition by environmental groups. These groups are proposing that the Alexander Archipelago wolf (Canis lupus ligoni) subspecies that inhabits the entire region and a distinct population segment of wolves on Prince of Wales Island are threatened or endangered with extinction.
Whether or not these wolves are endangered with extinction was beyond the scope of our study. However our research quantified the genetic variation of these wolves in southeast Alaska which can contribute to assessing their status as a subspecies.
Because the US Endangered Species Act (ESA) defines species as “species, subspecies, and distinct population segments”, these categories are all considered “species” for the ESA. Although this definition is not consistent with the scientific definition of species it has become the legal definition of species for the ESA.
Therefore we have two questions to consider:
Are the wolves in southeast Alaska a subspecies?
Are the wolves on Prince of Wales Island a distinct population segment?
The literature on subspecies and distinct population segment designation is vast, but it is important to understand that subspecies is a taxonomic category, and basically refers to a group of populations that share an independent evolutionary history.
Taxonomy is the science of biological classification and is based on evolutionary history and common ancestry (called phylogeny). Species, subspecies, and higher-level groups (e.g, a genus such as Canis) are classified based on common ancestry. For example, wolves and foxes share common ancestry and are classified in the same family (Canidae), while bobcats and lions are classified in a different family (Felidae) because they share a common ancestry that is different from foxes and wolves.
Wolf in southeast Alaska. Photo credit: Kristian Larson, the Alaska Dept of Fish and Game (Wildlife Conservation Division, Region I). Image used with permission.
Subspecies designations are often subjective because of uncertainty about the relationships among populations of the same species. This leads many scientists to reject or ignore the subspecies category, but because the ESA is the most powerful environmental law in the United States the analysis of subspecies is of great practical importance.
Our results and other research showed that the wolves in Southeast Alaska differed in allele frequencies compared to wolves in other regions. Allele frequencies reflect the distribution of genetic variation within and among populations. However, the wolves in southeast Alaska do not comprise a homogeneous population, and there is as much genetic variation among the Game Management Units (GMU) in southeast Alaska as there is between southeast Alaska and other areas.
Our research data showed that the wolves in southeast Alaska are not a homogeneous group, but consist of multiple populations with different histories of colonization, isolation, and interbreeding. The genetic data also showed that the wolves on Prince of Wales Island are not particularly differentiated compared to the overall differentiation in Southeast Alaska and do not support designation as a distinct population segment.
The overall pattern for wolves in southeast Alaska is not one of long term isolation and evolutionary independence and does not support a subspecies designation. Other authors, including biologists with the US Fish and Wildlife Service, also do not designate wolves in southeast Alaska as a subspecies and there is general recognition that North America wolf subspecies designations have been arbitrary and are not supported by genetic data.
There is growing recognition in the scientific community of unwarranted taxonomic inflation of wildlife species and subspecies designations to achieve conservation goals. Because the very nature of subspecies is vague, wildlife management and conservation should focus on populations, including wolf populations. This allows all of the same management actions as proposed for subspecies, but with increased scientific rigor.
Headline image credit: Alaskan wolf, by Douglas Brown. CC-BY-NC-SA-2.0 via Flickr.
For tigers, visiting your neighbor is just not as easy as it used to be. Centuries ago, tigers roamed freely across the landscape from India to Indonesia and even as far north as Russia. Today, tigers inhabit is just 7% of that historical range. And that 7% is distributed in tiny patches across thousands of kilometers.
Habitat destruction and poaching has caused serious declines in tiger populations – only about 3,000 tigers remain from a historical estimate of 100,000 just a century ago. Several organizations are concerned with conserving this endangered species. Currently, however, all conservation plans focus increasing the number of tigers. Our study shows that, if we are managing for a future with healthy tiger populations, we need to look beyond the numbers. We need to consider genetic diversity.
Genetic diversity is the raw material for evolution. Populations with low genetic diversity can have lower health and reproduction due to ‘inbreeding effects’. This was the case with the Florida panther – in the early 1990s there were just 30 Florida panthers left. Populations with low genetic diversity are also vulnerable when faced with challenges such as disease or changes in the environment.
Photo by Rachael A. Bay
Luckily for tigers, they don’t have low genetic diversity. They have very high genetic diversity, in fact. But the problem for tigers is that losing genetic diversity happens more quickly in many small, disconnected populations than in one large population. The question is: how can we keep that genetic diversity so that tigers never suffer the consequences of inbreeding effects.
We used computer simulations to predict how many tigers we would need in the future to keep the genetic diversity they already have. Our study shows that without connecting the small populations, the number of tigers necessary to maintain that variation is biologically impossible. However, if we can connect some of these populations – between tiger reserves or even between subspecies – the number of tigers needed to harbor all the genetic variation becomes much smaller and more feasible. Case studies have shown that introducing genetic material from distantly related populations can hugely benefit the health of a population in decline. In the case of the Florida panther, when individuals from another subspecies were introduced into the breeding population, the numbers began to rise.
We do need to increase the number of tigers in the wild. If we can’t stop poaching and habitat destruction, we will lose all wild tigers before we have a chance to worry about genetic diversity. But in planning to conserve this majestic animal for future generations we should make sure those future populations can thrive – and that means trying to keep genetic variation.
Journal of Heredity covers organismal genetics: conservation genetics of endangered species, population structure and phylogeography, molecular evolution and speciation, molecular genetics of disease resistance in plants and animals, genetic biodiversity and relevant computer programs.
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Image credit: Tigers at San Francisco Zoo. Photo by Rachael A. Bay. Do not reproduce without permission.
Rapid development of molecular genetics in recent decades has revolutionized our understanding of life and the natural world. Scientists in the 1970s suggested that the grey wolf might be the sole ancestor of domestic dogs, but it was only in 1997 that Carles Vilà, Peter Savolainen, Robert Wayne, and their co-authors provided the conclusive evidence on this based on the analysis of molecular genetic markers.
It is generally assumed that dogs domesticated in East Asia; however, several recent studies challenged this hypothesis. In 2013, a team of scientists showed that the alleles (i.e. different versions of the same gene) of both modern dogs and the fossilized remains from Europe are in fact shared with local wolves.
One can suppose that genes of European wolves are descended both from the animals domesticated thousands of years ago and from wild grey wolves, which might hybridize with domestic dogs for thousands of years after domestication. The role of ongoing hybridization in the evolution of dogs is not easy to infer, even with our advanced molecular methods. In Europe and the US, since at least the 20th century, the mating of non-feral dogs (even large-bodied breeds) has usually been under human control. In many tropical countries, where dogs are not controlled so tightly, grey wolves don’t exist at all.
Natia Kopaliani and her co-workers from Ilia State University, Tbilisi, Georgia, have been studying wolf-dog conflict in the Caucasus since 2007. During recent years, they collected and processed samples of both wolves and dogs from the region with molecular genetic methods. Georgia, like other countries of the Caucasus, eastern Turkey, Iran, and Central Asia, has large livestock-guarding dogs, usually called here Caucasian or Georgian shepherds, which are traditionally free-ranging, and have uncontrolled contacts with grey wolves common to the area. The vast majority of the samples in this study were taken from the shepherd dogs guarding herds of sheep in the Central part of the Greater Caucasus Mountains.
Sequencing mitochondrial DNA showed us that as many as 37% of the dogs shared maternal haplotypes with the local wolves. The proportion of wolves with recent dog ancestry, detected using microsatellite markers, was almost two times higher than that of wolves studied earlier in southern Europe, where feral dogs are still present. More surprising still was that almost the same proportion (nearly 10%) of the guarding dogs possessed the detected hybrid ancestry. These results suggest that mutual gene flow between wolves and dogs in the Caucasus (and, possibly, in other mountainous regions of West and Central Asia) is common, most likely continued for millennia, and had a substantial impact on gene pool of both the domestic and the wild Canis lupus. It does not appear that the hybridization had any negative impact on the dog features important for humans. It is probable that shepherds used to exterminate the hybrids that demonstrated undesired behavior, but that most of the dogs with recent wolf ancestry were integrated into the dog population without problems.
This study may help our understanding of the process of the domestication of dogs and some other domestic animals. Attributing the ancestry of domestic dogs to a few animals from a small area is an oversimplification of the real pattern. Indeed, some domestic lineages may expand faster than the others may. However, wherever both the wild and the domestic forms coexist, they regularly hybridize and we have no reason to think this was not the case all the time since the earliest domestication events. Hybridization may produce animals with undesirable traits, but the owners rapidly eliminate them; occasional hybridization increases effective population size and may help to avoid inbred effect. This isolated, tightly controlled way of dog breeding is a more recent development. Modern dog-keepers select the animals with well-known pedigrees and keep them away from wild animals. Nowadays, it may sound strange to allow a pet dog to interbreed with a wolf. However, the permanent intensive selection of dogs with desirable features was most likely an instrument to keep the breeds “in shape” rather than a peculiar selection of the pedigrees.
Journal of Heredity covers organismal genetics: conservation genetics of endangered species, population structure and phylogeography, molecular evolution and speciation, molecular genetics of disease resistance in plants and animals, genetic biodiversity and relevant computer programs.
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Image credits: Both images courtesy of Natia Kopaliani, co-author of the paper.
Do conservation genetics and ancient Greek history ever cross paths? Recently, a genetic study of a remnant population of elephants in Eritrea has also addressed an ancient mystery surrounding a battle in the Hellenistic world. After Alexander the Great died unexpectedly in 323 BC, his generals divided his territory, founding several empires. Their successors ended up fighting each other during the next few centuries, often using elephants to intimidate the enemy and disrupt military formations. The Seleucids, heirs to the lands neighboring India, traded treasure and territory for access to Indian war elephants. They fought the Ptolemaic dynasty of Egypt, seeking control of the lands between the two empires during the Syrian Wars. The Ptolemaic pharaohs, desperate for their own pachydermal tanks, established outposts in what is today the country of Eritrea, to capture African elephants for warfare.
Elephants from the two continents were put to the test at the Battle of Raphia in 217 BC, between Antiochus III and Ptolemy IV Philopater. In The Histories, which includes the only known account of African and Asian elephants meeting in warfare, the Greek historian Polybius described the resulting fiasco:
“Most of Ptolemy’s elephants, however, declined the combat, as is the habit of African elephants; for unable to stand the smell and the trumpeting of the Indian elephants, and terrified, I suppose, also by their great size and strength, they at once turn tail and take to flight before they get near them. This is what happened on the present occasion; when Ptolemy’s elephants were thus thrown into confusion and driven back on their own lines.”
As every school child knows, Asian elephants are smaller than African elephants. So why did Polybius get this wrong? One British writer, perhaps unconsciously affected by the corporal punishments meted out by Classics teachers to disruptive students at English schools, decided that Polybius must after all be correct. He pointed out that, although African savanna elephants are larger than Asian elephants, there is a different species of elephant that lives in the tropical forests of Africa, and which is smaller in size than the Asian elephant. Thus began the tale that the war elephants of the pharaohs were actually African forest elephants, ignoring the thousands of kilometers that separate the range of forest elephants from places where the Egyptians captured their war elephants. This tale was then perpetuated by subsequent authors, each citing authors before as definitive sources.
A savanna elephant in Kruger National Park, South Africa
In a recent conservation genetics study, we examined the elephants of Eritrea, the descendants of the population that was the source of Egyptian war elephants. Eritrea currently has the northernmost population of elephants in eastern Africa. Perhaps one or two hundred elephants persist there, in isolated and fragmented habitat. Using DNA isolated from non-invasively collected dung samples we examined three different genetic markers. First we looked at slow-evolving nuclear gene sequences in the Eritrean elephants. In every case the sites always had the same sequence found in hundreds of savanna elephants, and in no case did we ever get a match to sequences found across all forest elephants. This established that Eritrean elephants were savanna elephants.
When we then looked at very fast evolving regions of the nuclear genome, the Eritrean elephants proved to be a close match to savanna elephants in East Africa, and again were genetically unlike forest elephants. Finally, we looked at mitochondrial DNA, which often has a different pattern than other genetic markers in elephants. Mitochondrial DNA is transmitted only by females, and these females do not geographically disperse away from the natal heard. Very often, one can infer a signal of ancient genetic events that persist only in the pattern of the mitochondrial DNA. Yet in this case, the mitochondrial DNA agreed with the nuclear results: these were savanna elephants, and there was not the slightest trace of any ancient forest elephant presence in Eritrea.
Given this result, why did Polybius claim that the Asian elephants were larger than African elephants? It turns out that in the ancient world there was a legend that, due to the wet climate, animals were always larger in India than they were elsewhere. This legend was widespread among authors before and after Polybius. Go back and look at the way the translation of the Polybius text is worded. Even in translation, it is evident that Polybius has interjecting his own beliefs onto the account, and not recounting an actual observation.
Our genetic study indicated that the isolated population of elephants in Eritrea has low genetic diversity. Habitat loss and human-wildlife conflict are major concerns for conservation of this population, which luckily has not yet been impacted by China’s lust for illegal ivory. Increasing and protecting suitable habitat for their long-term survival is critical, and in the very long run it may become possible to create habitat corridors to other surviving but distant populations. Luckily, the government of Eritrea is committed to protecting the country’s natural environment, and has recently reported an increase in the range and number of elephants.
The Journal of Heredity covers organismal genetics: conservation genetics of endangered species, population structure and phylogeography, molecular evolution and speciation, molecular genetics of disease resistance in plants and animals, genetic biodiversity and relevant computer programs.
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Image credit: Savanna elephant in Kruger National Park, South Africa. By Felix Andrews (CC-BY-SA-3.0) via Wikimedia Commons.
By Bianca Haase
Cats are among the most common household pets and they share the same environment with humans and thus many of the risk factors. Obesity is a growing problem for feline health for the same reasons as it is in humans and has become a serious veterinary problem. Multiple diseases, such as type II diabetes mellitus and dermatosis, are associated with excess body weight and obesity in cats and may result in a lowered quality of life and potentially lead to an early death. Appleton et al. demonstrated that about 44% of cats developed impaired
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It's being called "a whale of a problem," and not just by me. According to research published in the Journal of Heredity, endangered Southern Resident orcas are mating within their family groups. This "genetic bottleneck" means the whales could be more susceptible to diseases, early mortality or failure to produce calves.
The study's lead author is Michael J. Ford, a scientist with the Northwest Fisheries Science Center in Seattle.
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