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| 2. |
- Agnvall, Beatrix, et al.
(författare)
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Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl (Gallus gallus)
- 2015
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Ingår i: Biology Letters. - : ROYAL SOC. - 1744-9561 .- 1744-957X. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- Domesticated animals tend to develop a coherent set of phenotypic traits. Tameness could be a central underlying factor driving this, and we therefore selected red junglefowl, ancestors of all domestic chickens, for high or low fear of humans during six generations. We measured basal metabolic rate (BMR), feed efficiency, boldness in a novel object (NO) test, corticosterone reactivity and basal serotonin levels (related to fearfulness) in birds from the fifth and sixth generation of the high- and low-fear lines, respectively (44-48 individuals). Corticosterone response to physical restraint did not differ between selection lines. However, BMR was higher in low-fear birds, as was feed efficiency. Low-fear males had higher plasma levels of serotonin and both low-fear males and females were bolder in an NO test. The results show that many aspects of the domesticated phenotype may have developed as correlated responses to reduced fear of humans, an essential trait for successful domestication.
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| 3. |
- Ahi, Ehsan Pashay, et al.
(författare)
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Expression levels of the tetratricopeptide repeat protein gene ttc39b covary with carotenoid-based skin colour in cichlid fish
- 2020
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 16:11
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Tidskriftsartikel (refereegranskat)abstract
- Carotenoid pigments play a major role in animal body colouration, generating strong interest in the genes involved in the metabolic processes that lead from their dietary uptake to their storage in the integument. Here, we used RNA sequencing (RNA-Seq) to test for differentially expressed genes in a taxonomically replicated design using three pairs of related cichlid fish taxa from the genera Tropheus and Aulonocara. Within each pair, taxa differed in terms of red and yellow body colouration, and high‐performance liquid chromatography (HPLC) analyses of skin extracts revealed different carotenoid profiles and concentrations across the studied taxa. Five genes were differentially expressed in all three yellow–red skin contrasts (dhrsx, nlrc3, tcaf2, urah and ttc39b), but only the tetratricopeptide repeat protein-coding gene ttc39b, whose gene product is linked to mammalian lipid metabolism, was consistently expressed more highly in the red skin samples. The RNA-Seq results were confirmed by quantitative PCR. We propose ttc39b as a compelling candidate gene for variation in animal carotenoid colouration. Since differential expression of ttc39b was correlated with the presence/absence of yellow carotenoids in a previous study, we suggest that ttc39b is more likely associated with the concentration of total carotenoids than with the metabolic formation of red carotenoids.
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| 4. |
- Ahlgren, Johan, et al.
(författare)
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Camouflaged or tanned: plasticity in freshwater snail pigmentation.
- 2013
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Ingår i: Biology letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 9:5, s. 4-20130464
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Tidskriftsartikel (refereegranskat)abstract
- By having phenotypically plastic traits, many organisms optimize their fitness in response to fluctuating threats. Freshwater snails with translucent shells, e.g. snails from the Radix genus, differ considerably in their mantle pigmentation patterns, with snails from the same water body ranging from being completely dark pigmented to having only a few dark patterns. These pigmentation differences have previously been suggested to be genetically fixed, but we propose that this polymorphism is owing to phenotypic plasticity in response to a fluctuating environment. Hence, we here aimed to assess whether common stressors, including ultraviolet radiation (UVR) and predation, induce a plastic response in mantle pigmentation patterns of Radix balthica. We show, in contrast to previous studies, that snails are plastic in their expression of mantle pigmentation in response to changes in UVR and predator threats, i.e. differences among populations are not genetically fixed. When exposed to cues from visually hunting fish, R. balthica increased the proportion of their dark pigmentation, suggesting a crypsis strategy. Snails increased their pigmentation even further in response to UVR, but this also led to a reduction in pattern complexity. Furthermore, when exposed to UVR and fish simultaneously, snails responded in the same way as in the UVR treatment, suggesting a trade-off between photoprotection and crypsis.
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| 5. |
- Ahlgren, Johan, et al.
(författare)
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Individual boldness is linked to protective shell shape in aquatic snails
- 2015
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Ingår i: Biology Letters. - London : Royal society. - 1744-9561 .- 1744-957X. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- The existence of consistent individual differences in behaviour ('animal personality') has been well documented in recent years. However, how such individual variation in behaviour is maintained over evolutionary time is an ongoing conundrum. A well-studied axis of animal personality is individual variation along a bold-shy continuum, where individuals differ consistently in their propensity to take risks. A predation-risk cost to boldness is often assumed, but also that the reproductive benefits associated with boldness lead to equivalent fitness outcomes between bold and shy individuals over a lifetime. However, an alternative or complementary explanation may be that bold individuals phenotypically compensate for their risky lifestyle to reduce predation costs, for instance by investing in more pronounced morphological defences. Here, we investigate the 'phenotypic compensation' hypothesis, i.e. that bold individuals exhibit more pronounced anti-predator defences than shy individuals, by relating shell shape in the aquatic snail Radix balthica to an index of individual boldness. Our analyses find a strong relationship between risk-taking propensity and shell shape in this species, with bolder individuals exhibiting a more defended shell shape than shy individuals. We suggest that this supports the 'phenotypic compensation' hypothesis and sheds light on a previously poorly studied mechanism to promote the maintenance of personality variation among animals.
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| 6. |
- Alexander, Michelle, et al.
(författare)
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Mitogenomic analysis of a 50-generation chicken pedigree reveals a rapid rate of mitochondrial evolution and evidence for paternal mtDNA inheritance
- 2015
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial genomes represent a valuable source of data for evolutionary research, but studies of their short-term evolution have typically been limited to invertebrates, humans and laboratory organisms. Here we present a detailed study of 12 mitochondrial genomes that span a total of 385 transmissions in a well-documented 50-generation pedigree in which two lineages of chickens were selected for low and high juvenile body weight. These data allowed us to test the hypothesis of time-dependent evolutionary rates and the assumption of strict maternal mitochondrial transmission, and to investigate the role of mitochondrial mutations in determining phenotype. The identification of a non-synonymous mutation in ND4L and a synonymous mutation in CYTB, both novel mutations in Gallus, allowed us to estimate a molecular rate of 3.13 x 10(-7) mutations/site/year (95% confidence interval 3.75 x 10(-8)-1.12 x 10(-6)). This is substantially higher than avian rate estimates based upon fossil calibrations. Ascertaining which of the two novel mutations was present in an additional 49 individuals also revealed an instance of paternal inheritance of mtDNA. Lastly, an association analysis demonstrated that neither of the point mutations was strongly associated with the phenotypic differences between the two selection lines. Together, these observations reveal the highly dynamic nature of mitochondrial evolution over short time periods.
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| 7. |
- Alsterberg, Christian, 1982, et al.
(författare)
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Multiple stressors and multifunctionality: limited effects on an illuminated benthic system
- 2014
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- The bulk of experiments that study stressor effects on ecosystem functioning consider only individual functions one at a time, and such narrow focus may well bias our understanding of the overall impact on ecosystem functioning. We used data from six published experiments in which marine illuminated sediment systems were exposed to nutrient enrichment, toxicants, sedimentation and warming, either alone or in combination. Measured functions were primary production, community respiration, inorganic nitrogen and phosphorus fluxes, and autotrophic biomass. We calculated two indices of multifunctionality that simultaneously considered all six functions: (i) a weighted average level of the functions and (ii) the number of functions that simultaneously exceed a critical threshold level. Stressors affected individual functions both positively and negatively, but multifunctionality was generally unaffected by both single and joint stressors. The filtering capacity of coastal illuminated sediment systems thus appears resilient to exposure to moderate levels of multiple stressors, most probably due to the robustness of the benthic microalgal community. We recommend using a multifunctionality approach in future studies on cumulative stressor effects on ecosystem functioning, particularly when considering functions related to ecosystem services.
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| 8. |
- Alström, Per, et al.
(författare)
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Discovery of a relict lineage and monotypic family of passerine birds.
- 2014
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of one of the most comprehensive datasets to date of the largest passerine bird clade, Passerida, identified 10 primary well-supported lineages corresponding to Sylvioidea, Muscicapoidea, Certhioidea, Passeroidea, the ‘bombycillids’ (here proposed to be recognized as Bombycilloidea), Paridae/Remizidae (proposed to be recognized as Paroidea), Stenostiridae, Hyliotidae, Regulidae (proposed to be recognized as Reguloidea) and spotted wren-babbler Spelaeornis formosus. The latter was found on a single branch in a strongly supported clade with Muscicapoidea, Certhioidea and Bombycilloidea, although the relationships among these were unresolved. We conclude that the spotted wren-babbler represents a relict basal lineage within Passerida with no close extant relatives, and we support the already used name Elachura formosa and propose the new family name Elachuridae for this single species.
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| 9. |
- Arnemo, Jon
(författare)
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Heart rate during hyperphagia differs between two bear species
- 2019
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Hyperphagia is a critical part of the yearly cycle of bears when they gain fat reserves before entering hibernation. We used heart rate as a proxy to compare the metabolic rate between the Asian black bear (Ursus thibetanus) in Japan and the Eurasian brown bear (Ursus arctos) in Sweden from summer into hibernation. In the hyperphagic period, black bears feed on fat- and carbohydrate-rich hard masts whereas brown bears feed on sugar-rich berries. Availability of hard masts has quantitative and spatial annual fluctuations, which might require increased activity and result in intraspecific stress. Using generalized additive mixed models we analysed the differences in heart rate between the two species. Black bears had decreased heart rates during summer but had doubled heart rate values throughout the hyperphagic period compared to brown bears. This letter illustrates the different physiological consequences of seasonal differences in food availability in two species of the same genus dealing with the same phenological challenge.
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| 10. |
- Arnqvist, Göran, et al.
(författare)
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Sex-role reversed nuptial feeding reduces male kleptoparasitism of females in Zeus bugs (Heteroptera : Veliidae)
- 2006
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 2:4, s. 491-493
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Tidskriftsartikel (refereegranskat)abstract
- Males of a variety of taxa occasionally steal food secured by their mates. In some spiders and insects, males rely entirely on this form of intraspecific kleptoparasitism for their subsistence. However, this male strategy may be costly for females and a variety of different female counteradaptations have been proposed. In Zeus bugs ( Phoreticovelia spp.), males ride on the back of their mates for extended periods and females produce a gland secretion that males feed on. By experimentally occluding the dorsal glands in females and varying food availability, we show that nuptial feeding by females reduces the extent to which the males kleptoparasitize their mates. We suggest that females have, at least in part, evolved this unique form of nuptial feeding as a counteradaptation to reduce the rate of kleptoparasitism by males.
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