Sometimes slower is better: slow-exploring birds are more sensitive to changes in a vocal discrimination task

Animal personality, defined as consistent individual differences across context and time, has attracted much recent research interest in the study of animal behaviour. More recently, this field has begun to examine how such variation arose and is maintained within populations. The habitat-dependent selection hypothesis, which posits that animals with differing personality types may fare better (i.e. have a fitness advantage) in different habitats, suggests one possible mechanism. In the current experiment, we tested whether slow- and fast-exploring black-capped chickadees (Poecile atricapillus), determined by performance in a novel environment exploration task, perform differentially when the demands of an acoustic operant discrimination (cognitive) task were altered following successful task acquisition. We found that slow-exploring birds learn to reverse previously learned natural category rules more quickly than faster exploring conspecifics. In accordance with the habitat-dependent selection hypothesis, and previous work with great tits (Parus major), a close relative of the black-capped chickadee, our results suggest that fast-exploring birds may perform better in stable, predictable environments where forming a routine is advantageous, while slow-exploring birds are favoured in unstable, unpredictable environments, where task demands often change. Our results also support a hypothesis derived from previous work with great tits; slow-exploring birds may be generally more flexible (i.e. able to modify their behaviour in accordance with changes in environmental stimuli) in some learning tasks.     

县域耕地非农化、非粮化与乡村人口空心化的耦合协调关系——以长江经济带为例

耕地非农化、非粮化的不断扩大严重影响了我国的粮食安全,亟需研究其演变机制和管控措施。基于1990、2000、2010和2020年四期土地覆盖数据和农业劳动力数据,利用耦合协调度模型和探索性时空数据分析(ESTDA)方法,分析了长江经济带县域耕地非农化、非粮化和乡村人口空心化的时空演化特征及其耦合协调关系。结果表明:①非农化呈现东高西低的格局,且存在围绕中心城市高值集聚的态势。非粮化则大致呈现出西高东低的倾向,远离大城市的边远县域非粮化程度较高。研究期内非农化和非粮化呈整体加剧趋势,乡村人口空心化程度显著提升。②非农化、非粮化和乡村人口空心化之间呈现较强耦合作用,失调区域逐渐扩大。③非农化、非粮化和乡村人口空心化耦合协调度存在明显的空间集聚现象并逐渐增强。高值集聚区主要分布在上游地区且数量逐渐减少,低值集聚区分布相对分散。④非农化、非粮化和乡村人口空心化耦合协调度具有较强时空动态特征,但县域及其邻域协同变动的比例较高,表明具有较强的局域整合性。     

Reproductive and Neurobehavioral Effects of Clothianidin Administered to Mice in the Diet

Clothianidin was given in the diet to provide levels of 0% (control), 0.003%, 0.006%, and 0.012% from 5 weeks of age of the F₀ generation to 11 weeks of age of the F₁ generation in mice. Selected reproductive and neurobehavioral parameters were measured. In exploratory behavior in the F₀ generation, average time of movement, number of rearing, and rearing time of adult males increased significantly in a dose‐related manner. There was no adverse effect of clothianidin on litter size, litter weight, or sex ratio at birth. The average body weight of male and female offspring was increased significantly in a dose‐related manner during the early lactation period. With respect to behavioral developmental parameters, swimming head angle at postnatal day (PND) 7 of male offspring was accelerated significantly in a dose‐related manner. Negative geotaxis at PND 7 of female offspring was accelerated significantly in a dose‐related manner. For movement activity of exploratory behavior in the F₁ generation, number of rearing of female offspring increased significantly in a dose‐related manner. Movement time of adult males increased significantly in a dose‐related manner. The dose levels of clothianidin in the present study produced several adverse effects in neurobehavioral parameters in mice. Nevertheless, it would appear that the levels of the actual dietary intake of clothianidin are unlikely to produce adverse effects in humans.     

Cognitive impairment in rats after long-term exposure to GSM-900 mobile phone radiation

Considering the frequent use of mobile phones, we have directed attention to possible implications on cognitive functions. In this study we investigated in a rat model the long-term effects of protracted exposure to Global System for Mobile Communication-900 MHz (GSM-900) radiation. Out of a total of 56 rats, 32 were exposed for 2 h each week for 55 weeks to radio-frequency electromagnetic radiation at different SAR levels (0.6 and 60 mW/kg at the initiation of the experimental period) emitted by a (GSM-900) test phone. Sixteen animals were sham exposed and eight animals were cage controls, which never left the animal house. After this protracted exposure, GSM-900 exposed rats were compared to sham exposed controls. Effects on exploratory behaviour were evaluated in the open-field test, in which no difference was seen. Effects on cognitive functions were evaluated in the episodic-like memory test. In our study, GSM exposed rats had impaired memory for objects and their temporal order of presentation, compared to sham exposed controls (P = 0.02). Detecting the place in which an object was presented was not affected by GSM exposure. Our results suggest significantly reduced memory functions in rats after GSM microwave exposure (P = 0.02).     

Shoal sex composition affects exploration in the Mediterranean killifish

As a consequence of sexual selection, males and females may exhibit wide behavioural differences, for example, spatial behaviour. In fish, the two sexes often show different exploratory tendencies. This sex difference has been usually studied by testing individual fish. As many fish species live in social groups with different sex composition, the aforementioned approach might not picture the natural variation of the exploratory behaviour expressed by males and females. Here, we observed shoals of four Mediterranean killifish, Aphanius fasciatus, with three different sex compositions (4 females, 4 males, or 2 females and 2 males) during the exploration of a novel environment. Sex composition of the shoals did not predict the latency to emerge from a shelter into the novel environment. However, once emerged, shoals composed by four males displayed reduced exploratory behaviour compared to 4‐female and mixed‐sex shoals. These results indicated that sex differences in exploration subsist also at group level and highlighted the importance of sex composition in determining the behaviour of the entire shoal.     

Effects of Early Contact with Maternal Parent on Locomotor Activity and Exploratory Behavior in Spiderlings of Hogna carolinensis (Araneae: Lycosidae)

In this study we investigated the effect of rearing conditions (stimulus complexity) on the locomotor activity and exploratory behavior of spiderlings of Hogna carolinensis in a novel open field arena. Experimental groups consisted of spiderlings that were allowed to remain with their maternal parent for 1 day (group 1), 3 days (group 2), and 5 days (group 3) after emergence from their egg sacs, and those who had no contact (group 4) with a maternal parent. Spiderlings that had physical contact with their mothers for 3 and 5 days required significantly less time to enter the arena, to reach the central grid area of the arena, and for an initial return to the start box than spiderlings in groups 1 and 4. In addition, spiderlings in groups 2 and 3 exhibited a significantly greater number of grid crossings as compared to groups 1 and 4, and spent more time in the arena. This is the first demonstration that environmental complexity, in the form of a social factor such as physical contact with a maternal parent, can affect the subsequent behavior of spiderlings.     

Behavioral effects of the aqueous extract of Guiera senegalensis in mice and rats

Behavioral effects of the aqueous extract of Guiera senegalensis on the central nervous system of mice and rats were investigated. Spontaneous motor activity, pentobarbital sleeping time, amphetamine-stereotyped behavior, exploratory activity and performance on treadmills (rota-rod) were evaluated. The results revealed that the aqueous extract of G. senegalensis reduced spontaneous motor activity in mice, prolonged the duration of pentobarbital sleeping time in rats and attenuated amphetamine-induced stereotype behavior in rats. The extract also decreased exploratory activity in mice and had no observable effects on motor coordination (rota-rod) at the doses tested. The results suggested that the crude aqueous extract of G. senegalensis possesses some biologically active principles that are sedative in nature.     

Abnormal behavior,striatal dopamine turnover and opioid peptide gene expression in histamine‐deficient mice

Hypothalamic histaminergic neurons regulate a variety of homeostatic, metabolic and cognitive functions. Recent data have suggested a modulatory role of histamine and histamine receptors in shaping striatal activity and connected the histaminergic system to neuropsychiatric disorders. We characterized exploratory behavior and striatal neurotransmission in mice lacking the histamine producing enzyme histidine decarboxylase (Hdc). The mutant mice showed a distinct behavioral pattern during exploration of novel environment, specifically, increased frequency of rearing seated against the wall, jumping and head/body shakes. This behavioral phenotype was associated with decreased levels of striatal dopamine and serotonin and increased level of dopamine metabolite DOPAC. Gene expression levels of dynorphin and enkephalin, opioids released by medium spiny neurons of striatal direct and indirect pathways respectively, were lower in Hdc mutant mice than in control animals. A low dose of amphetamine led to similar behavioral and biochemical outcomes in both genotypes. Increased striatal dopamine turnover was observed in Hdc KO mice after treatment with dopamine precursor l ‐Dopa. Overall, our study suggests a role for striatal dopamine and opioid peptides in formation of distinct behavioral phenotype of Hdc KO mice.     

Multiple Facets of Exploratory Behavior in House Crickets (Acheta domesticus): Split Personalities or Simply Different Behaviors?

Behavioral ecologists are increasingly interested in patterns of repeatable variation in behaviors. The study of this variation, under the label ‘animal personality’, frequently makes assumptions both in regards to what the ecological significance of particular behavioral responses might be and whether different methodologies in fact test the same behavior. Here, using house crickets (Acheta domesticus), we tested whether stereotypical approaches to quantifying repeatable variation in exploratory behavior measured the same behaviors. We found that house cricket exploratory behavior was highly repeatable in two populations (repeatability: 0.37–0.51). However, exploratory behavior across two different testing methods was not strongly correlated (r = ?0.17 to 0.14). This suggests that either different behaviors or distinct components of exploratory behavior were being measured. Our results also support recent criticisms that care needs to be taken in describing personality traits.     

Association between DRD4 gene polymorphism and personality variation in great tits: a test across four wild populations

Polymorphisms in the dopamine receptor D4 gene (DRD4) have been related to individual variation in novelty‐seeking or exploratory behaviour in a variety of animals, including humans. Recently, the human DRD4 orthologue was sequenced in a wild bird, the great tit (Parus major) and a single nucleotide polymorphism in exon 3 of this gene (SNP830) was shown to be associated with variation in exploratory behaviour of lab‐raised individuals originating from a single wild population. Here we test the generality of this finding in a large sample of free‐living individuals from four European great tit populations, including the originally sampled population. We demonstrate that the association between SNP830 genotype and exploratory behaviour also exists in free‐living birds from the original population. However, in the other three populations we found only limited evidence for an association: in two populations the association appeared absent; while in one there was a nonsignificant tendency. We could not confirm a previously demonstrated interaction with another DRD4 polymorphism, a 15 bp indel in the promoter region (ID15). As yet unknown differences in genetic or environmental background could explain why the same genetic polymorphism (SNP830) has a substantial effect on exploratory behaviour in one population, explaining 4.5–5.8% of the total variance—a large effect for a single gene influencing a complex behavioural trait—but not in three others. The confirmation of an association between SNP830 genotype and personality‐related behaviour in a wild bird population warrants further research into potential fitness effects of the polymorphism, while also the population differences in the strength of the association deserve further investigation. Another important future challenge is the identification of additional loci influencing avian personality traits in the wild.