This passage is adapted from Adam K. Fetterman and Kai Sassenberg, “The Reputational Consequences of Failed Replications and Wrongness Admission among Scientists", first published in December 2015 by PLOS ONE.

We like to think of science as a purely rational. However, scientists are human and often identify with their work. Therefore, it should not be controversial to suggest that emotions are involved in replication discussions. Adding to this inherently emotionally volatile situation, the recent increase in the use of social media and blogs by scientists has allowed for instantaneous, unfiltered, and at times emotion-based commentary on research. Certainly social media has the potential to lead to many positive outcomes in science–among others, to create a more open science. To some, however, it seems as if this ease of communication is also leading to the public tar and feathering of scientists. Whether these assertions are true is up for debate, but we assume they are a part of many scientists’ subjective reality. Indeed, when failed replications are discussed in the same paragraphs as questionable research practices, or even fraud, it is hard to separate the science from the scientist. Questionable research practices and fraud are not about the science; they are about the scientist. We believe that these considerations are at least part of the reason that we find the overestimation effect that we do, here.

Even so, the current data suggests that while many are worried about how a failed replication would affect their reputation, it is probably not as bad as they think. Of course, the current data cannot provide evidence that there are no negative effects; just that the negative impact is overestimated. That said, everyone wants to be seen as competent and honest, but failed replications are a part of science. In fact, they are how science moves forward!

While we imply that these effects may be exacerbated by social media, the data cannot directly speak to this. However, any one of a number of cognitive biases may add support to this assumption and explain our findings. For example, it may be that a type of availability bias or pluralistic ignorance of which the more vocal and critical voices are leading individuals to judge current opinions as more negative than reality. As a result, it is easy to conflate discussions about direct replications with “witch- hunts” and overestimate the impact on one’s own reputation. Whatever the source may be, it is worth looking at the potential negative impact of social media in scientific conversations.

If the desire is to move science forward, scientists need to be able to acknowledge when they are wrong. Theories come and go, and scientists learn from their mistakes (if they can even be called “mistakes”). This is the point of science. However, holding on to faulty ideas flies in the face of the scientific method. Even so, it often seems as if scientists have a hard time admitting wrongness. This seems doubly true when someone else fails to replicate a scientist’s findings. In some cases, this may be the proper response. Just as often, though, it is not. In most cases, admitting wrongness will have relatively fewer ill effects on one’s reputation than not admitting and it may be better for reputation. It could also be that wrongness admission repairs damage to reputation.

It may seem strange that others consider it less likely that questionable research practices, for example, were used when a scientist admits that they were wrong. However, it does make sense from the standpoint that wrongness admission seems to indicate honesty. Therefore, if one is honest in one domain, they are likely honest in other domains. Moreover, the refusal to admit might indicate to others that the original scientist is trying to cover something up. The lack of significance of most of the interactions in our study suggests that it even seems as if scientists might already realize this. Therefore, we can generally suggest that scientists admit they are wrong, but only when the evidence suggests they should.

The chart below maps how scientists view others' work (left) and how they suspect others will view their own work (right) if the researcher (the scientist or another, depending on the focus) admitted to engaging in questionable research practices.

Adapted from Fetterman & Sassenberg, "The Reputational Consequences of Failed Replications and Wrongness Admission among Scientists." December 9, 2015, PLOS One.

Which of the following hypothetical situations would the author find most likely?

This passage is adapted from Adam K. Fetterman and Kai Sassenberg, “The Reputational Consequences of Failed Replications and Wrongness Admission among Scientists", first published in December 2015 by PLOS ONE.

We like to think of science as a purely rational. However, scientists are human and often identify with their work. Therefore, it should not be controversial to suggest that emotions are involved in replication discussions. Adding to this inherently emotionally volatile situation, the recent increase in the use of social media and blogs by scientists has allowed for instantaneous, unfiltered, and at times emotion-based commentary on research. Certainly social media has the potential to lead to many positive outcomes in science–among others, to create a more open science. To some, however, it seems as if this ease of communication is also leading to the public tar and feathering of scientists. Whether these assertions are true is up for debate, but we assume they are a part of many scientists’ subjective reality. Indeed, when failed replications are discussed in the same paragraphs as questionable research practices, or even fraud, it is hard to separate the science from the scientist. Questionable research practices and fraud are not about the science; they are about the scientist. We believe that these considerations are at least part of the reason that we find the overestimation effect that we do, here.

Even so, the current data suggests that while many are worried about how a failed replication would affect their reputation, it is probably not as bad as they think. Of course, the current data cannot provide evidence that there are no negative effects; just that the negative impact is overestimated. That said, everyone wants to be seen as competent and honest, but failed replications are a part of science. In fact, they are how science moves forward!

While we imply that these effects may be exacerbated by social media, the data cannot directly speak to this. However, any one of a number of cognitive biases may add support to this assumption and explain our findings. For example, it may be that a type of availability bias or pluralistic ignorance of which the more vocal and critical voices are leading individuals to judge current opinions as more negative than reality. As a result, it is easy to conflate discussions about direct replications with “witch- hunts” and overestimate the impact on one’s own reputation. Whatever the source may be, it is worth looking at the potential negative impact of social media in scientific conversations.

If the desire is to move science forward, scientists need to be able to acknowledge when they are wrong. Theories come and go, and scientists learn from their mistakes (if they can even be called “mistakes”). This is the point of science. However, holding on to faulty ideas flies in the face of the scientific method. Even so, it often seems as if scientists have a hard time admitting wrongness. This seems doubly true when someone else fails to replicate a scientist’s findings. In some cases, this may be the proper response. Just as often, though, it is not. In most cases, admitting wrongness will have relatively fewer ill effects on one’s reputation than not admitting and it may be better for reputation. It could also be that wrongness admission repairs damage to reputation.

It may seem strange that others consider it less likely that questionable research practices, for example, were used when a scientist admits that they were wrong. However, it does make sense from the standpoint that wrongness admission seems to indicate honesty. Therefore, if one is honest in one domain, they are likely honest in other domains. Moreover, the refusal to admit might indicate to others that the original scientist is trying to cover something up. The lack of significance of most of the interactions in our study suggests that it even seems as if scientists might already realize this. Therefore, we can generally suggest that scientists admit they are wrong, but only when the evidence suggests they should.

The chart below maps how scientists view others' work (left) and how they suspect others will view their own work (right) if the researcher (the scientist or another, depending on the focus) admitted to engaging in questionable research practices.

Adapted from Fetterman & Sassenberg, "The Reputational Consequences of Failed Replications and Wrongness Admission among Scientists." December 9, 2015, PLOS One.

Which of the following hypothetical situations would the author find most likely?

The following is an excerpt from Agnes Grey, an autobiographical novel by Anne Bronte that follows the life of a governess working in wealthy British households in the 19th century.

To avoid trouble and confusion, I have taken my pupils one by one, and discussed their various qualities; but this can give no adequate idea of being worried by the whole three together; when, as was often the case, all were determined to ‘be naughty, and to tease Miss Grey, and put her in a passion.’

Sometimes, on such occasions, the thought has suddenly occurred to me—’If they could see me now!’ meaning, of course, my friends at home; and the idea of how they would pity me has made me pity myself—so greatly that I have had the utmost difficulty to restrain my tears: but I have restrained them, till my little tormentors were gone to dessert, or cleared off to bed (my only prospects of deliverance), and then, in all the bliss of solitude, I have given myself up to the luxury of an unrestricted burst of weeping. But this was a weakness I did not often indulge: my employments were too numerous, my leisure moments too precious, to admit of much time being given to fruitless lamentations.

I particularly remember one wild, snowy afternoon, soon after my return in January: the children had all come up from dinner, loudly declaring that they meant ‘to be naughty;’ and they had well kept their resolution, though I had talked myself hoarse, and wearied every muscle in my throat, in the vain attempt to reason them out of it. I had got Tom pinned up in a corner, whence, I told him, he should not escape till he had done his appointed task. Meantime, Fanny had possessed herself of my workbag, and was rifling its contents—and spitting into it besides. I told her to let it alone, but to no purpose, of course. ‘Burn it, Fanny!’ cried Tom: and this command she hastened to obey. I sprang to snatch it from the fire, and Tom darted to the door. ‘Mary Ann, throw her desk out of the window!’ cried he: and my precious desk, containing my letters and papers, my small amount of cash, and all my valuables, was about to be precipitated from the three-story window. I flew to rescue it. Meanwhile Tom had left the room, and was rushing down the stairs, followed by Fanny. Having secured my desk, I ran to catch them, and Mary Ann came scampering after. All three escaped me, and ran out of the house into the garden, where they plunged about in the snow, shouting and screaming in exultant glee.

What must I do? If I followed them, I should probably be unable to capture one, and only drive them farther away; if I did not, how was I to get them in? And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?

The passage implies that:

The following is an excerpt from Agnes Grey, an autobiographical novel by Anne Bronte that follows the life of a governess working in wealthy British households in the 19th century.

To avoid trouble and confusion, I have taken my pupils one by one, and discussed their various qualities; but this can give no adequate idea of being worried by the whole three together; when, as was often the case, all were determined to ‘be naughty, and to tease Miss Grey, and put her in a passion.’

Sometimes, on such occasions, the thought has suddenly occurred to me—’If they could see me now!’ meaning, of course, my friends at home; and the idea of how they would pity me has made me pity myself—so greatly that I have had the utmost difficulty to restrain my tears: but I have restrained them, till my little tormentors were gone to dessert, or cleared off to bed (my only prospects of deliverance), and then, in all the bliss of solitude, I have given myself up to the luxury of an unrestricted burst of weeping. But this was a weakness I did not often indulge: my employments were too numerous, my leisure moments too precious, to admit of much time being given to fruitless lamentations.

I particularly remember one wild, snowy afternoon, soon after my return in January: the children had all come up from dinner, loudly declaring that they meant ‘to be naughty;’ and they had well kept their resolution, though I had talked myself hoarse, and wearied every muscle in my throat, in the vain attempt to reason them out of it. I had got Tom pinned up in a corner, whence, I told him, he should not escape till he had done his appointed task. Meantime, Fanny had possessed herself of my workbag, and was rifling its contents—and spitting into it besides. I told her to let it alone, but to no purpose, of course. ‘Burn it, Fanny!’ cried Tom: and this command she hastened to obey. I sprang to snatch it from the fire, and Tom darted to the door. ‘Mary Ann, throw her desk out of the window!’ cried he: and my precious desk, containing my letters and papers, my small amount of cash, and all my valuables, was about to be precipitated from the three-story window. I flew to rescue it. Meanwhile Tom had left the room, and was rushing down the stairs, followed by Fanny. Having secured my desk, I ran to catch them, and Mary Ann came scampering after. All three escaped me, and ran out of the house into the garden, where they plunged about in the snow, shouting and screaming in exultant glee.

What must I do? If I followed them, I should probably be unable to capture one, and only drive them farther away; if I did not, how was I to get them in? And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?

The passage implies that:

The following is an excerpt from Agnes Grey, an autobiographical novel by Anne Bronte that follows the life of a governess working in wealthy British households in the 19th century.

To avoid trouble and confusion, I have taken my pupils one by one, and discussed their various qualities; but this can give no adequate idea of being worried by the whole three together; when, as was often the case, all were determined to ‘be naughty, and to tease Miss Grey, and put her in a passion.’

Sometimes, on such occasions, the thought has suddenly occurred to me—’If they could see me now!’ meaning, of course, my friends at home; and the idea of how they would pity me has made me pity myself—so greatly that I have had the utmost difficulty to restrain my tears: but I have restrained them, till my little tormentors were gone to dessert, or cleared off to bed (my only prospects of deliverance), and then, in all the bliss of solitude, I have given myself up to the luxury of an unrestricted burst of weeping. But this was a weakness I did not often indulge: my employments were too numerous, my leisure moments too precious, to admit of much time being given to fruitless lamentations.

I particularly remember one wild, snowy afternoon, soon after my return in January: the children had all come up from dinner, loudly declaring that they meant ‘to be naughty;’ and they had well kept their resolution, though I had talked myself hoarse, and wearied every muscle in my throat, in the vain attempt to reason them out of it. I had got Tom pinned up in a corner, whence, I told him, he should not escape till he had done his appointed task. Meantime, Fanny had possessed herself of my workbag, and was rifling its contents—and spitting into it besides. I told her to let it alone, but to no purpose, of course. ‘Burn it, Fanny!’ cried Tom: and this command she hastened to obey. I sprang to snatch it from the fire, and Tom darted to the door. ‘Mary Ann, throw her desk out of the window!’ cried he: and my precious desk, containing my letters and papers, my small amount of cash, and all my valuables, was about to be precipitated from the three-story window. I flew to rescue it. Meanwhile Tom had left the room, and was rushing down the stairs, followed by Fanny. Having secured my desk, I ran to catch them, and Mary Ann came scampering after. All three escaped me, and ran out of the house into the garden, where they plunged about in the snow, shouting and screaming in exultant glee.

What must I do? If I followed them, I should probably be unable to capture one, and only drive them farther away; if I did not, how was I to get them in? And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?

Which of the following best describes the attitude of Miss Grey toward the parents of the three children?

The following is an excerpt from Agnes Grey, an autobiographical novel by Anne Bronte that follows the life of a governess working in wealthy British households in the 19th century.

To avoid trouble and confusion, I have taken my pupils one by one, and discussed their various qualities; but this can give no adequate idea of being worried by the whole three together; when, as was often the case, all were determined to ‘be naughty, and to tease Miss Grey, and put her in a passion.’

Sometimes, on such occasions, the thought has suddenly occurred to me—’If they could see me now!’ meaning, of course, my friends at home; and the idea of how they would pity me has made me pity myself—so greatly that I have had the utmost difficulty to restrain my tears: but I have restrained them, till my little tormentors were gone to dessert, or cleared off to bed (my only prospects of deliverance), and then, in all the bliss of solitude, I have given myself up to the luxury of an unrestricted burst of weeping. But this was a weakness I did not often indulge: my employments were too numerous, my leisure moments too precious, to admit of much time being given to fruitless lamentations.

I particularly remember one wild, snowy afternoon, soon after my return in January: the children had all come up from dinner, loudly declaring that they meant ‘to be naughty;’ and they had well kept their resolution, though I had talked myself hoarse, and wearied every muscle in my throat, in the vain attempt to reason them out of it. I had got Tom pinned up in a corner, whence, I told him, he should not escape till he had done his appointed task. Meantime, Fanny had possessed herself of my workbag, and was rifling its contents—and spitting into it besides. I told her to let it alone, but to no purpose, of course. ‘Burn it, Fanny!’ cried Tom: and this command she hastened to obey. I sprang to snatch it from the fire, and Tom darted to the door. ‘Mary Ann, throw her desk out of the window!’ cried he: and my precious desk, containing my letters and papers, my small amount of cash, and all my valuables, was about to be precipitated from the three-story window. I flew to rescue it. Meanwhile Tom had left the room, and was rushing down the stairs, followed by Fanny. Having secured my desk, I ran to catch them, and Mary Ann came scampering after. All three escaped me, and ran out of the house into the garden, where they plunged about in the snow, shouting and screaming in exultant glee.

What must I do? If I followed them, I should probably be unable to capture one, and only drive them farther away; if I did not, how was I to get them in? And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?

Which of the following best describes the attitude of Miss Grey toward the parents of the three children?

The following is an excerpt from Agnes Grey, an autobiographical novel by Anne Bronte that follows the life of a governess working in wealthy British households in the 19th century.

To avoid trouble and confusion, I have taken my pupils one by one, and discussed their various qualities; but this can give no adequate idea of being worried by the whole three together; when, as was often the case, all were determined to ‘be naughty, and to tease Miss Grey, and put her in a passion.’

Sometimes, on such occasions, the thought has suddenly occurred to me—’If they could see me now!’ meaning, of course, my friends at home; and the idea of how they would pity me has made me pity myself—so greatly that I have had the utmost difficulty to restrain my tears: but I have restrained them, till my little tormentors were gone to dessert, or cleared off to bed (my only prospects of deliverance), and then, in all the bliss of solitude, I have given myself up to the luxury of an unrestricted burst of weeping. But this was a weakness I did not often indulge: my employments were too numerous, my leisure moments too precious, to admit of much time being given to fruitless lamentations.

I particularly remember one wild, snowy afternoon, soon after my return in January: the children had all come up from dinner, loudly declaring that they meant ‘to be naughty;’ and they had well kept their resolution, though I had talked myself hoarse, and wearied every muscle in my throat, in the vain attempt to reason them out of it. I had got Tom pinned up in a corner, whence, I told him, he should not escape till he had done his appointed task. Meantime, Fanny had possessed herself of my workbag, and was rifling its contents—and spitting into it besides. I told her to let it alone, but to no purpose, of course. ‘Burn it, Fanny!’ cried Tom: and this command she hastened to obey. I sprang to snatch it from the fire, and Tom darted to the door. ‘Mary Ann, throw her desk out of the window!’ cried he: and my precious desk, containing my letters and papers, my small amount of cash, and all my valuables, was about to be precipitated from the three-story window. I flew to rescue it. Meanwhile Tom had left the room, and was rushing down the stairs, followed by Fanny. Having secured my desk, I ran to catch them, and Mary Ann came scampering after. All three escaped me, and ran out of the house into the garden, where they plunged about in the snow, shouting and screaming in exultant glee.

What must I do? If I followed them, I should probably be unable to capture one, and only drive them farther away; if I did not, how was I to get them in? And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?

The passage suggests that Miss Grey

The following is an excerpt from Agnes Grey, an autobiographical novel by Anne Bronte that follows the life of a governess working in wealthy British households in the 19th century.

To avoid trouble and confusion, I have taken my pupils one by one, and discussed their various qualities; but this can give no adequate idea of being worried by the whole three together; when, as was often the case, all were determined to ‘be naughty, and to tease Miss Grey, and put her in a passion.’

Sometimes, on such occasions, the thought has suddenly occurred to me—’If they could see me now!’ meaning, of course, my friends at home; and the idea of how they would pity me has made me pity myself—so greatly that I have had the utmost difficulty to restrain my tears: but I have restrained them, till my little tormentors were gone to dessert, or cleared off to bed (my only prospects of deliverance), and then, in all the bliss of solitude, I have given myself up to the luxury of an unrestricted burst of weeping. But this was a weakness I did not often indulge: my employments were too numerous, my leisure moments too precious, to admit of much time being given to fruitless lamentations.

I particularly remember one wild, snowy afternoon, soon after my return in January: the children had all come up from dinner, loudly declaring that they meant ‘to be naughty;’ and they had well kept their resolution, though I had talked myself hoarse, and wearied every muscle in my throat, in the vain attempt to reason them out of it. I had got Tom pinned up in a corner, whence, I told him, he should not escape till he had done his appointed task. Meantime, Fanny had possessed herself of my workbag, and was rifling its contents—and spitting into it besides. I told her to let it alone, but to no purpose, of course. ‘Burn it, Fanny!’ cried Tom: and this command she hastened to obey. I sprang to snatch it from the fire, and Tom darted to the door. ‘Mary Ann, throw her desk out of the window!’ cried he: and my precious desk, containing my letters and papers, my small amount of cash, and all my valuables, was about to be precipitated from the three-story window. I flew to rescue it. Meanwhile Tom had left the room, and was rushing down the stairs, followed by Fanny. Having secured my desk, I ran to catch them, and Mary Ann came scampering after. All three escaped me, and ran out of the house into the garden, where they plunged about in the snow, shouting and screaming in exultant glee.

What must I do? If I followed them, I should probably be unable to capture one, and only drive them farther away; if I did not, how was I to get them in? And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?

The passage suggests that Miss Grey

The following passage is adapted from Ricki Lewis, "Did Donkeys Arise from an Inverted Chromosome?", originally published 2018 in PLOSOne Blogs.

In the world of genome sequencing, donkeys haven’t received nearly as much attention as horses. But now a report on a new-and-improved genome sequence of Willy, a donkey (Equus asinus) jack 5 born at the Copenhagen Zoo in 1997, appears in the new issue of Science Advances, from Gabriel Renaud, of the Centre for GeoGenetics, Natural History Museum of Denmark. (A female is a jenny or jennet.) The new view provides clues to how donkeys may have branched from horses along the tree of evolution.

Horses and their relatives, past and present, are genetically peculiar in that their chromosomes are rearranged, with respect to each other. That should prevent them from producing viable hybrids – yet they do. Donkeys have 62 chromosomes and horses have 64. A mule comes from the mating of a male donkey and a female horse, and has 63 chromosomes. Mules are known for their intelligence, calm, stamina, and persistence. Their horse-like bodies perched on donkey-like limbs make them ideal for hauling tourists around the Grand Canyon and schlepping supplies in combat situations. The ears are large like those of the horse mom, and mules make a sound that begins as a whinny and becomes a bray.

The complementary couple, a female donkey and a male horse, produces a hinny, smaller than a mule. Hinnies are the flip side of the mule, with a donkey’s physique atop horsey limbs, and short donkey ears. They’re rarer than mules, but also have 63 chromosomes. It’s easy to mix them up.

Comparing Willy’s genome to a horse genome revealed their close evolutionary relationship. Only about 15% of horse genes aren’t also in the donkey genome, and only about 10% of a donkey’s genes don’t have counterparts in the horse. Most of the genes that they share provide basic “housekeeping” functions like dismantling proteins, repairing DNA, enabling embryonic development, and controlling cell division. So that’s why a copy of each genome can smush together to yield mules and hinnies.

A second form of information encoded in genomes, in addition to the A, C, T, G sequence, is the pattern of whether the two variants of individual genes are different (heterozygous) or the same (homozygous). Many contiguous homozygous genes form a “run of homozygosity” (ROH).

An ROH indicates a chromosome chunk, perhaps as long as millions of DNA bases, that’s the same from each of an individual’s parents, who in turn inherited it from a shared ancestor, like a grandparent that cousins share. The longer the ROH, the more recent the shared ancestor, because it takes time for mutations to accrue that would break the sameness of the sequence.

Scrutinizing ROHs can reveal recent inbreeding and domestication, help to reconstruct possible branching patterns of evolution, and, more practically, help ancestry companies assign the DNA in spit samples to geographic areas where people’s ancestors might have come from. The new study compared ROHs for the three zebra and three ass species, confirming that Willy’s most recent ancestors were Somali wild asses.

The researchers used Chicago HiRise assembly technology to up the quality of Willy’s genome sequence. “This new assembly allowed us to identify fine chromosomal rearrangements between the horse and the donkey that likely played an active role in their divergence and, ultimately, speciation,” they write.

The bigger pieces enabled them to zero in on DNA sequences where chromosomes contort, such as inversions (where a sequence flips) or translocations (where different chromosome types exchange parts). These events could have fueled the reproductive isolation of small populations that can expand into speciation.

If eventually sperm with one inverted chromosome fertilized eggs with the same inversion, animals would have been conceived in which both copies of the chromosome are inverted – and they’d be fertile with each other, but not with horses. Once a subpopulation with the inversion became established, further genetic changes would separate them further from the ancestral horse.

Which of the following is suggested about the gene inversion?

The following passage is adapted from Ricki Lewis, "Did Donkeys Arise from an Inverted Chromosome?", originally published 2018 in PLOSOne Blogs.

In the world of genome sequencing, donkeys haven’t received nearly as much attention as horses. But now a report on a new-and-improved genome sequence of Willy, a donkey (Equus asinus) jack 5 born at the Copenhagen Zoo in 1997, appears in the new issue of Science Advances, from Gabriel Renaud, of the Centre for GeoGenetics, Natural History Museum of Denmark. (A female is a jenny or jennet.) The new view provides clues to how donkeys may have branched from horses along the tree of evolution.

Horses and their relatives, past and present, are genetically peculiar in that their chromosomes are rearranged, with respect to each other. That should prevent them from producing viable hybrids – yet they do. Donkeys have 62 chromosomes and horses have 64. A mule comes from the mating of a male donkey and a female horse, and has 63 chromosomes. Mules are known for their intelligence, calm, stamina, and persistence. Their horse-like bodies perched on donkey-like limbs make them ideal for hauling tourists around the Grand Canyon and schlepping supplies in combat situations. The ears are large like those of the horse mom, and mules make a sound that begins as a whinny and becomes a bray.

The complementary couple, a female donkey and a male horse, produces a hinny, smaller than a mule. Hinnies are the flip side of the mule, with a donkey’s physique atop horsey limbs, and short donkey ears. They’re rarer than mules, but also have 63 chromosomes. It’s easy to mix them up.

Comparing Willy’s genome to a horse genome revealed their close evolutionary relationship. Only about 15% of horse genes aren’t also in the donkey genome, and only about 10% of a donkey’s genes don’t have counterparts in the horse. Most of the genes that they share provide basic “housekeeping” functions like dismantling proteins, repairing DNA, enabling embryonic development, and controlling cell division. So that’s why a copy of each genome can smush together to yield mules and hinnies.

A second form of information encoded in genomes, in addition to the A, C, T, G sequence, is the pattern of whether the two variants of individual genes are different (heterozygous) or the same (homozygous). Many contiguous homozygous genes form a “run of homozygosity” (ROH).

An ROH indicates a chromosome chunk, perhaps as long as millions of DNA bases, that’s the same from each of an individual’s parents, who in turn inherited it from a shared ancestor, like a grandparent that cousins share. The longer the ROH, the more recent the shared ancestor, because it takes time for mutations to accrue that would break the sameness of the sequence.

Scrutinizing ROHs can reveal recent inbreeding and domestication, help to reconstruct possible branching patterns of evolution, and, more practically, help ancestry companies assign the DNA in spit samples to geographic areas where people’s ancestors might have come from. The new study compared ROHs for the three zebra and three ass species, confirming that Willy’s most recent ancestors were Somali wild asses.

The researchers used Chicago HiRise assembly technology to up the quality of Willy’s genome sequence. “This new assembly allowed us to identify fine chromosomal rearrangements between the horse and the donkey that likely played an active role in their divergence and, ultimately, speciation,” they write.

The bigger pieces enabled them to zero in on DNA sequences where chromosomes contort, such as inversions (where a sequence flips) or translocations (where different chromosome types exchange parts). These events could have fueled the reproductive isolation of small populations that can expand into speciation.

If eventually sperm with one inverted chromosome fertilized eggs with the same inversion, animals would have been conceived in which both copies of the chromosome are inverted – and they’d be fertile with each other, but not with horses. Once a subpopulation with the inversion became established, further genetic changes would separate them further from the ancestral horse.

Which of the following is suggested about the gene inversion?