Cat Journal Club

"Cat Journal Club is erratic like its namesake animal"

[monpponders]

Nearly half of size reduction in dogs explained by six genes

Rimbault M and Beale HC et al. (2013) Derived variants at six genes explain nearly half of size reduction in dog breeds. Genome Research 23:1985-1995. doi: 10.1101/gr.157339.113

Somewhere between 15,000 and 100,000 years ago, people started domesticating wolves through intense artificial selection for whatever traits they fancied. A majority of modern breeds were developed in last 300 years, today resulting in 175 AKC recognized breeds that are codified by very distinct standards. Such intense selection pressure means that within breeds, there’s going to be very little genetic diversity in those distinct traits [[not all purebreds are inbred, but they did start out that way, which is why you see more health issues in purebred dogs]]. 

The genetic loci determining size in particular have very strong signatures of selection. The CanMap project used 60,968 SNPs [[single nucleotide polymorphisms, or single DNA base pair changes]] to highlight a number of phenotype-associated loci, which the authors then fine-mapped to four autosomal loci and then further mapped to 6 specific gene loci polymorphisms. Another gene, IGF1, was implicated as a size factor in other studies, so it was also examined. This brought the total number of markers up to 7. [[Markers referring to specific DNA sequences that you know the location of and therefore can actually find.]]

Experiment:

1. Drew blood from AKC show dogs from 93 recognized breeds across the full range of canine body size. Average AKC “standard breed weight” (SBW) was used as a surrogate for body size.  All dogs were unrelated to one another at the grandparent level so there was no similarity due to recent inbreeding. At least 2 males and 2 females of each breed were tested.

2. Genotyped the dogs at the 7 markers [[looked at the dogs’ gene sequences at these 7 specific points]].

3. Determined the ancestral allele [[what the genome looked like before humans started making puggles]] for each marker by looking at 26 grey wolves, 2 red wolves, 2 coyotes. 

They found that genotypes at each marker corresponded to differences in size, with dogs possessing more derived markers trending towards a smaller and smaller standard breed weight. For each variant, SBWs of dogs homozygous for the derived allele were significantly less than SBWs of dogs homozygous for the ancestral genes. SBWs of D/D dogs were also significantly less than SBWs of heterozygotes (A/D) at four of the seven markers. 

These genes generally could not explain any of the size variation for the large dogs. Nearly all of the rottweilers were actually derived for one of the markers, IGF1, which was highly unusual. But, if a dog with a high SBW did have any derived markers, it was usually in the same place - IGF1. Large dogs clearly must have other size factors at play.

Genotypes at these seven loci (conservatively) account for between 46 and 52.5% of the SBW variance. This is crazy. Half of the size variation in small purebreds can be traced back to (essentially) 7 transcription errors that somehow only changed the size of the dog without too many other problems. Other mutations in these same genes have been implicated in growth disorders in mice and humans. 

Just as a comparison, we’ve identified 180 loci significantly associated with height in humans, and these are highly heritable genes, but these loci all together only account for around 10% of the variation in human heights. Granted, these were all show dogs so environmental factors (diet changes, poor upbringings, etc) were likely out of the picture, but the amount of control humans have exerted over the dog genome in just 300 years is astounding. People must have really wanted those puggles. 

[monpponders]

Negative association between religiousness and altruism in children

Decety J et al. (2015) The negative association between religiousness and children’s altruism across the world. Current Biology 25, 1-5.  http://dx.doi.org/10.1016/j.cub.2015.09.056

First impression: this paper is structured very strangely - the headers are just Results, Discussion, and Experimental Procedures. It reads like a normal paper otherwise, just a quirk.

Altruism is defined as a cost to the donor at the benefit of the recipient. [[This doesn’t need to be a definite loss, but can also be the increase in the probability of a death/dismemberment, as in the case of alarm calls.]] Prosocial behaviors, such as altruism, tend to be transmitted early in development. In humans, children tend to develop altruistic behavior (as exhibited by sharing) between preschool and late childhood [[undefined]]. 

Altruism in children in religious households, as well as parental perception of child’s altruistic tendencies has not been studied on a global scale. If religion promotes prosocial behaviors, then children growing up in religious homes should show stronger altruistic behavior. 

Sample tasks (the dictator game) were performed across 1,170 children ages 5-12 from 6 different countries.  Children did not self identify as religious - the parents did. Religiosity was also indexed by frequency of religious practice, household spirituality, and overall religiousness as indicated by the caregivers’ completion of the Duke Religiousness Questionnaire (DRQ). In-group vs. out-group biases were controlled for. Age was overall predictive of total resources shared, but children from a religiously identifying households were significantly less likely to share than children from a non-religiously identifying household. 

After determining this, the authors compared non-religious households to Christian and Muslim households (the other religious households were too small a sample size and not included in this analysis). Age, country of origin, socioeconomic status, and religious identification were statistically significant predictors of sharing. Paired comparisons shows that while there was not a significant difference in generosity between Christian and Muslim children, both groups were significantly less altruistic than non-religious children. This relationship between altruism and religiousness was strongest in the older children (8-12 years of age). 

Children in Muslim households judged interpersonal harm as more mean than children from Christian households, who also judged it as more mean than children from non-religious households [[so there’s that at least]]. Children from Muslim households also differed in their ratings of deserved punishment for interpersonal harm, significantly erring on the “harsher” side than Christian/nonreligious households. 

As for parental rating, Christian households were significantly higher in parent-rated child sensitivity to injustice and child empathy than Muslim or nonreligious households. 

Religiosity is not associated with increased altruism in young children, and actually demonstrates that children from households identifying as either Christian or Muslim were less altruistic than children from non-religious households. This increased with age: children with a longer experience of religion in the household exhibited the greatest negative relations. 

This paper had a killer closing line: ”More generally, they call into question whether religion is vital for moral development, supporting the idea that the secularization of moral discourse will not reduce human kindness - in fact, it will do just the opposite.”

BAM. Sassy author is sassy.

[monpponders]

Lateralized behavior in the domestic cat

Wells DL and Millsopp S (2009) Lateralized behavior in the domestic cat,Felis silvestris catus. Animal Behavior 78.2: 537-541. doi:10.1016/j.anbehav.2009.06.010

90% of humans are right handed, but few studies have been done on lateralization in other species, mostly focusing on nonhuman primates (yay anthropocentricity!) A few studies have found that unneutered male dogs are more likely to use their left paws than female dogs or neutered dogs which suggesting the role of sex hormones in motor skills. Male horses also showed the same left bias, but other factors, such as training, may have affected motor bias.

Handedness often varies as a function of task complexity or conditioning, as any of us oppressed left handers will tell you, so multiple tests should be done to actually elucidate handedness. This study subjected only neutered/spayed domestic cats to three different tasks to determine whether or not the animals had significant paw preference.

Task 1: Food retrieval - make cat aware of treat, stick treat in a jar small enough that they can’t use face to retrieve. Observe first paw used.

Task 2: Tease cat with cat string toy/anything in the air. Observe first paw used.

Task 3: Drag toy along ground so cat will chase. Observe first paw used.    

Repeat tasks 100 times (not in one day or cat will murder you, see future post).

The cats showed a stronger paw preference for Task 1 (the most complex task) than Task 3 or Task 2 (may be more reflex oriented). Direction of the cats’ paw preference was significantly related to animals’ sex, with males being left biased. Previously, studies had not been able to show a sex based significant difference in handedness at the population level, but this could’ve been due to simply a higher n for females.

Conclusion: I think all three boys of the ginger frat are right pawed. I wonder if there’s any sort of relationship between owner handedness and cat handedness. Like if they’ve been conditioned to get more attention from the owner’s right or left side, depending on the owner’s handedness, would that condition their own handedness in response?