Hexbyte Glen Cove Cavalier King Charles spaniels carry more harmful genetic variants than other breeds thumbnail

Hexbyte Glen Cove Cavalier King Charles spaniels carry more harmful genetic variants than other breeds

Hexbyte Glen Cove

Comparisons of dachshunds with and without signs of heart disease were used to help identify mutations that potentially predispose cavalier King Charles spaniels to develop MMVD. Credit: Måns Engelbrektsson, Swedish Kennel Club, CC-BY 4.0 (creativecommons.org/licenses/by/4.0/)

Recent dog breeding practices have loaded up cavalier King Charles spaniels with disease-causing mutations, including variants linked to the common heart condition, myxomatous mitral valve disease (MMVD). Erik Axelsson of Uppsala University and colleagues published these new findings September 2nd in the journal PLOS Genetics.

The past 300 years of dog breeding have created an incredible diversity of breeds with various sizes, shapes, and abilities. Unfortunately, this process has also caused many breeds to become more inbred and more likely to inherit . The study’s researchers wanted to know whether recent breeding practices had increased the number of disease-causing variants in . They sequenced entire genomes from 20 dogs from eight common breeds, such as beagles, German shepherds, and golden retrievers. They found that the cavalier King Charles spaniel, which experienced the most intense breeding, carried more harmful genetic variants than the other breeds they examined.

The researchers also looked for genetic variants in the cavalier King Charles spaniel genomes linked to MMVD. In this condition, the mitral valve in the degenerates, allowing blood to leak from the back into the left atrium. They identified two genetic variants linked to the disease, which appear to regulate a gene that codes for a common protein in heart muscle. The findings offer a potential explanation for why the cavalier King Charles spaniel is predisposed to develop the disease.

The especially large number of potentially harmful genes in the genomes of cavalier King Charles spaniels, compared to other dogs, likely resulted from its breeding history. Records suggest that small spaniel-type dogs have existed for at least 1,000 years and were popular at royal courts for several hundred years throughout Asia and Europe, including at the court of King Charles II (1630-1685). These spaniels experienced several “bottlenecks” where only a small percentage of the population passed on their genes to the next generation. The bottlenecks may have made the harmful genes more common in the cavalier King Charles spaniel genome before the dog achieved recognition as a breed in 1945.

Axelsson adds, “We find that recent breeding may have led to an accelerated accumulation of harmful mutations in certain dog breeds. In the Cavalier King Charles spaniel specifically, one or several of these mutations affect heart muscle protein NEBL and may predispose this to devastating heart disease.”



More information:
Axelsson E, Ljungvall I, Bhoumik P, Conn LB, Muren E, Ohlsson Å, et al. (2021) The genetic consequences of dog breed formation—Accumulation of deleterious genetic variation and fixation of mutations associated with myxomatous mitral valve disease in cavalier King Charles spaniels. PLoS Genet 17(9): e1009726. doi.org/10.1371/journal.pgen.1009726

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Cavalier King Charles spaniels carry more harmful genetic variants than other breeds (2021, September 2)
retrieved 2 September 2021
from https://phys.org/news/2021-09-cavalier-king-charles-spaniels-genetic.html

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Hexbyte Glen Cove Charles Darwin was right about why insects are losing the ability to fly thumbnail

Hexbyte Glen Cove Charles Darwin was right about why insects are losing the ability to fly

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Credit: Unsplash/CC0 Public Domain

Most insects can fly.

Yet scores of species have lost that extraordinary ability, particularly on islands.

On the small islands that lie halfway between Antarctica and continents like Australia, almost all the insects have done so.

Flies walk, moths crawl.

“Of course, Charles Darwin knew about this wing loss habit of island insects,” says Ph.D. candidate Rachel Leihy, from the Monash University School of Biological Sciences.

“He and the famous botanist Joseph Hooker had a substantial argument about why this happens. Darwin’s position was deceptively simple. If you fly, you get blown out to sea. Those left on land to produce the next generation are those most reluctant to fly, and eventually evolution does the rest. Voilà.”

But since Hooker expressed his doubt, many other scientists have too.

In short, they have simply said Darwin got it wrong.

Yet almost all of these discussions have ignored the place that is the epitome of flight loss—those ‘sub-Antarctic’ islands. Lying in the ‘roaring forties’ and ‘furious fifties’, they’re some of the windiest places on Earth.

“If Darwin really got it wrong, then wind would not in any way explain why so many insects have lost their ability to fly on these islands,” said Rachel.

Using a large, new dataset on insects from sub-Antarctic and Arctic , Monash University researchers examined every idea proposed to account for flight loss in insects, including Darwin’s wind idea.

Reporting today in Proceedings of the Royal Society B, they show that Darwin was right for this ‘most windy of places’. None of the usual ideas (such as those proposed by Hooker) explain the extent of flight loss in sub-Antarctic insects, but Darwin’s idea does. Although in a slightly varied form, in keeping with modern ideas on how flight loss actually evolves.

Windy conditions make insect flight more difficult and energetically costly. Thus, stop investing in and its expensive underlying machinery (wings, wing muscles) and redirect the resources to reproduction.

“It’s remarkable that after 160 years, Darwin’s ideas continue to bring insight to ecology,” said Rachel, the lead author of the paper.

Professor Steven Chown, also from the School of Biological Sciences, added that the Antarctic region is an extraordinary laboratory in which to resolve some of the world’s most enduring mysteries and test some of its most important ideas.



More information:
Wind plays a major but not exclusive role in the prevalence of insect flight loss on remote islands, Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2020.2121

Citation:
Charles Darwin was right about why insects are losing the ability to fly (2020, December 8)
retrieved 9 December 2020
from https://phys.org/news/2020-12-charles-darwin-insects-ability.html

This document is subject to copyright. Apart from any fair

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