Captivity and habituation to humans raise curiosity in vervet monkeys

The cognitive mechanisms causing intraspecific behavioural differences between wild and captive animals remain poorly understood. Although diminished neophobia, resulting from a safer environment and more “free” time, has been proposed to underlie these differences among settings, less is known about how captivity influences exploration tendency. Here, we refer to the combination of reduced neophobia and increased interest in exploring novelty as “curiosity”, which we systematically compared across seven groups of captive and wild vervet monkeys (Chlorocebus pygerythrus) by exposing them to a test battery of eight novel stimuli. In the wild sample, we included both monkeys habituated to human presence and unhabituated individuals filmed using motion-triggered cameras. Results revealed clear differences in number of approaches to novel stimuli among captive, wild-habituated and wild-unhabituated monkeys. As foraging pressure and predation risks are assumed to be equal for all wild monkeys, our results do not support a relationship between curiosity and safety or free time. Instead, we propose “the habituation hypothesis” as an explanation of why well-habituated and captive monkeys both approached and explored novelty more than unhabituated individuals. We conclude that varying levels of human and/or human artefact habituation, rather than the risks present in natural environments, better explain variation in curiosity in our sample of vervet monkeys.

Evolutionary genomics of grape (Vitis viniferassp.vinifera) domestication

We gathered genomic data from grapes (Vitis viniferassp.vinifera), a clonally propagated perennial crop, to address three ongoing mysteries about plant domestication. The first is the duration of domestication; archaeological evidence suggests that domestication occurs over millennia, but genetic evidence indicates that it can occur rapidly. We estimated that our wild and cultivated grape samples diverged ∼22,000 years ago and that the cultivated lineage experienced a steady decline in population size (Ne) thereafter. The long decline may reflect low-intensity management by humans before domestication. The second mystery is the identification of genes that contribute to domestication phenotypes. In cultivated grapes, we identified candidate-selected genes that function in sugar metabolism, flower development, and stress responses. In contrast, candidate-selected genes in the wild sample were limited to abiotic and biotic stress responses. A genomic region of high divergence corresponded to the sex determination region and included a candidate male sterility factor and additional genes with sex-specific expression. The third mystery concerns the cost of domestication. Annual crops accumulate putatively deleterious variants, in part due to strong domestication bottlenecks. The domestication of perennial crops differs from that of annuals in several ways, including the intensity of bottlenecks, and it is not yet clear if they accumulate deleterious variants. We found that grape accessions contained 5.2% more deleterious variants than wild individuals, and these were more often in a heterozygous state. Using forward simulations, we confirm that clonal propagation leads to the accumulation of recessive deleterious mutations but without decreasing fitness.

Morphometric changes of Triatoma flavida Neiva, 1911 (Hemiptera:Triatominae) in the transition from sylvatic to laboratory conditions

The one-generational metric changes occurring in Triatoma flavida (Hemiptera: Triatominae) when carried from its wild habitat (caves) to laboratory, were examined using traditional morphometric techniques. As for other species of Triatoma, Rhodnius or Panstrongylus studied in similar conditions, a significant reduction of head, thorax and wing size was observed. Sexual dimorphism of the wings, while present in the wild sample, was not detected anymore in the laboratory individuals. Biological significance and epidemiological importance are discussed.

Experimental study of gene flow between wild and cultivated Pennisetum glaucum

Under natural conditions, wild and cultivated pearl millet, Pennisetum glaucum (L.) R.Br., exchanged genes for millenia and, nevertheless, maintain high morphological differentiation. Under experimental conditions in the Sahel, hybridization between wild and cultivated pearl millet was measured using isozymic markers and interpreted in relation to the phenology of the plants. Gene flows were asymmetric, engendering 8% of hybrids in the progeny of the wild phenotype, 45% in that of the cultivated phenotype, and 39% in that of the intermediate "shibra" phenotype; these last two phenotypes constitute the sample of cultivated pearl millet. The proportion of hybrids in the progeny of the wild sample was time dependent during the flowering phase of cultivated pearl millet. The proportion of hybrids produced by the cultivated pearl millet was not time dependent. In the seeds produced by the cultivated phenotype along its reproductive phase, the proportion of viable seeds was negatively correlated with the frequency of hybrids. Likewise, the speed of germination of seeds produced by the cultivated or the shibra phenotypes was negatively correlated with the frequency of the hybrids that they contained. The effects of balancing among genetic intermixing, isolation and reproduction barriers, and differential anthropic and natural selection pressures are discussed to better understand the evolution and the maintenance of the polymorphism of Pennisetum glaucum. Key words: pearl millet, wild pearl millet, Pennisetum glaucum, gene flow, domestication, hybrid.