Pup provisioning in the cooperatively breeding African wild dog, Lycaon pictus, is driven by pack size, social status and age

Division of labour, in terms of providing for offspring, in obligate cooperatively breeding mammalian species is poorly understood.To understand offspring provisioning in a cooperatively breeding canid, we analysed a long-term dataset comprising 22 African wild dog, Lycaon pictus,denning events (nine packs over nine consecutive years).We investigated the effects of sex, age class, social status, and pack size on the likelihood and frequency of regurgitating food to pups at the den. We found that the interaction of social status and pack size affected the likelihood of regurgitation. Specifically, when in a large (>15) pack, dominant individuals were less likely to regurgitate than subordinate individuals. However, in smaller (£15) packs, dominant individuals were more likely to regurgitate than subordinate individuals.We also found that the interaction of age and pack size affected the frequency of regurgitation. Specifically, in large packs, yearlings regurgitated more frequently per observation period than adults. Contrastingly, in smaller packs, adults regurgitated more frequently.Sex did not affect pup provisioning.We suggest that these contrasting patterns of helping are best explained by a strong selection pressure for individual behaviour that results in larger pack sizes in this species. When in larger packs, costs are shared as the division of labour spreads amongst individuals. In smaller packs, a division of labour requires individuals that already experience costs (such as reproduction) to be further burdened by provisioning. Overall, our results support that the need for more helpers to care for offspring contributes to the evolutionary consequence of an inverse density dependence.http://www.sawma.co.zaam2019Veterinary Tropical Disease

Functional MRI of Sentence Comprehension in Children with Dyslexia: Beyond Word Recognition

Sentence comprehension (SC) studies in typical and impaired readers suggest that reading for meaning involves more extensive brain activation than reading isolated words. Thus far, no reading disability/dyslexia (RD) studies have directly controlled for the word recognition (WR) components of SC tasks, which is central for understanding comprehension processes beyond WR. This experiment compared SC to WR in 29, 9–14 year olds (15 typical and 14 impaired readers). The SC-WR contrast for each group showed activation in left inferior frontal and extrastriate regions, but the RD group showed significantly more activation than Controls in areas associated with linguistic processing (left middle/superior temporal gyri), and attention and response selection (bilateral insula, right cingulate gyrus, right superior frontal gyrus, and right parietal lobe). Further analyses revealed this overactivation was driven by the RD group's response to incongruous sentences. Correlations with out-of-scanner measures showed that better word- and text-level reading fluency was associated with greater left occipitotemporal activation, whereas worse performance on WR, fluency, and comprehension (reading and oral) were associated with greater right hemisphere activation in a variety of areas, including supramarginal and superior temporal gyri. Results provide initial foundations for understanding the neurobiological correlates of higher-level processes associated with reading comprehension