Host personality predicts cuckoo egg rejection in Daurian redstarts Phoenicurus auroreus

In species that are subject to brood parasitism, individuals often vary in their responses to parasitic eggs, with some rejecting the eggs while others do not. While some factors, such as host age (breeding experience), the degree of egg matching and the level of perceived risk of brood parasitism have been shown to influence host decisions, much of the variation remains unexplained. The host personality hypothesis suggests that personality traits of the host influence its response to parasitic eggs, but few studies have tested this. We investigated the relationship between two personality traits (exploration and neophobia) and a physiological trait (breathing rate) of the host, and egg-rejection behaviour in a population of Daurian redstarts Phoenicurus auroreus in northeast China. We first show that exploratory behaviour and the response to a novel object are repeatable for individual females and strongly covary, indicating distinct personality types. We then show that fast-exploring and less neophobic hosts were more likely to reject parasitic eggs than slow-exploring and more neophobic hosts. Variation in breathing rate—a measure of the stress-response—did not affect rejection behaviour. Our results demonstrate that host personality, along the bold-shy continuum, predicts the responses to parasitic eggs in Daurian redstarts, with bold hosts being more likely to reject parasitic eggs.

The Pacific Tree-Parasitic Fungus Cyclocybe parasitica Exhibits Monokaryotic Fruiting, Showing Phenotypes Known from Bracket Fungi and from Cyclocybe aegerita

Cyclocybe parasitica is a wood-destroying parasitic edible mushroom growing on diverse broad-leafed trees in New Zealand and other Pacific areas. Recent molecular systematics of European Cyclocybe aegerita, a newly delimited Asian phylum and of related species, corroborated the distinction of the chiefly saprobic cultivated edible mushroom C. aegerita from C. parasitica. Here, we show that C. parasitica exhibits a morpho-physiological trait characteristic to its European cousin, i.e., monokaryotic fruiting sensu stricto (basidiome formation without mating). Monokaryotic fruiting structures formed by C. parasitica ICMP 11668-derived monokaryons were categorized into four phenotypes. One of them displays ulcer-like structures previously reported from bracket fungi. Histology of dikaryotic and monokaryotic C. parasitica fruiting structures revealed anatomical commonalities and differences between them, and towards monokaryotic fruiting structures of C. aegerita. Mating experiments with C. parasitica strains representative of each fruiting phenotype identified compatible sibling monokaryons. Given reports on hypothetically monokaryotic basidiome field populations of ‘C. aegerita sensu lato’, it seems worthwhile to prospectively investigate whether monokaryotic fruiting s.str. occurs in nature. Sampling from such populations including karyotyping, comparative -omics, and competition assays may help to answer this question and provide evidence whether this trait may confer competitive advantages to a species capable of it.

Domestication effects on aggressiveness: Comparison of biting motivation and bite force between wild and domesticated finches

ABSTRACTDomesticated animals evolve unique traits, known as domestication phenotypes or the domestication syndrome, due to their adaptation to a captive environment and changes in selection pressures. After being tamed, the Bengalese finch (Lonchura striata var. domestica) has undergone behavioural and physiological trait changes that differ from those of its wild ancestor, the white-rumped munia (Lonchura striata). The Bengalese finch has complex songs, lower fear response, and lower corticosterone levels than those in the white-rumped munia. We hypothesized that domesticated finches increase the effort to reproduce in lieu of maintaining fitness for survival as needed in the wild. Aggressiveness and bite performance affect survival rates and reproductive success, and are good indicators of adaptability in the natural environment. Therefore, we compared the aggressiveness and biting force of white-rumped munias with those of Bengalese finches to explore the evolutionary mechanisms of behavioural changes due to domestication. We found that the Bengalese finch had decreased aggressiveness (incidence of aggressive biting birds and the number of bite responses) and bite force than those in the white-rumped munia due to domestication. Therefore, we believe they could allocate more resources for breeding that would otherwise be needed for coping with predators through aggression.

Stressor-induced ecdysis and thecate cyst formation in the armoured dinoflagellates Prorocentrum cordatum

Ecdysis, the process of extensive cell covering rearrangement, represents a remarkable physiological trait of dinoflagellates. It is involved in the regulation of the population and bloom dynamics of these microorganisms, since it is required for the formation of their thin-walled cysts. This study presents laboratory data on ecdysis in Prorocentrum cordatum, a harmful dinoflagellate species of high environmental significance. We studied external stressors triggering this process and changes in the cell ultrastructure accompanying it. Our experiments showed that mass ecdysis and formation of cysts in P. cordatum could be induced by centrifugation, temperature decrease, changes in salinity, and treatment by 2,6-dichlorobenzonitrile, whereas temperature increase, changes in pH and treatment by tetracycline did not have this effect. Obtained cysts of P. cordatum did not contain the pellicular layer and were formed in the end of the first stage of this process, i.e. removal of the plasma membrane and the outer amphiesmal vesicle membrane, whereas its second stage, removal of theca, represented excystment. Based on our findings, we conclude that such cysts can be attributed to thecate cysts and suggest P. cordatum as a promising model organism for the investigation of cellular and molecular aspects of ecdysis in dinoflagellates.

Comparison of Static and Dynamic Assays When Quantifying Thermal Plasticity of Drosophilids

Numerous assays are used to quantify thermal tolerance of arthropods including dynamic ramping and static knockdown assays. The dynamic assay measures a critical temperature while the animal is gradually heated, whereas the static assay measures the time to knockdown at a constant temperature. Previous studies indicate that heat tolerance measured by both assays can be reconciled using the time × temperature interaction from “thermal tolerance landscapes” (TTLs) in unhardened animals. To investigate if this relationship remains true within hardened animals, we use a static assay to assess the effect of heat hardening treatments on heat tolerance in 10 Drosophila species. Using this TTL approach and data from the static heat knockdown experiments, we model the expected change in dynamic heat knockdown temperature (CTmax: temperature at which flies enter coma) and compare these predictions to empirical measurements of CTmax. We find that heat tolerance and hardening capacity are highly species specific and that the two assays report similar and consistent responses to heat hardening. Tested assays are therefore likely to measure the same underlying physiological trait and provide directly comparable estimates of heat tolerance. Regardless of this compliance, we discuss why and when static or dynamic assays may be more appropriate to investigate ectotherm heat tolerance.

Intraspecific trait variation influences physiological performance and fitness in the South Africa shrub genus Protea (Proteaceae)

Background and Aims Global plant trait datasets commonly identify trait relationships that are interpreted to reflect fundamental trade-offs associated with plant strategies, but often these trait relationships are not identified when evaluating them at smaller taxonomic and spatial scales. In this study we evaluate trait relationships measured on individual plants for five widespread Protea species in South Africa to determine whether broad-scale patterns of structural trait (e.g. leaf area) and physiological trait (e.g. photosynthetic rates) relationships can be detected within natural populations, and if these traits are themselves related to plant fitness. Methods We evaluated the variance structure (i.e. the proportional intraspecific trait variation relative to among-species variation) for nine structural traits and six physiological traits measured in wild populations. We used a multivariate path model to evaluate the relationships between structural traits and physiological traits, and the relationship between these traits and plant size and reproductive effort. Key Results While intraspecific trait variation is relatively low for structural traits, it accounts for between 50 and 100 % of the variation in physiological traits. Furthermore, we identified few trait associations between any one structural trait and physiological trait, but multivariate regressions revealed clear associations between combinations of structural traits and physiological performance (R2 = 0.37–0.64), and almost all traits had detectable associations with plant fitness. Conclusions Intraspecific variation in structural traits leads to predictable differences in individual-level physiological performance in a multivariate framework, even though the relationship of any particular structural trait to physiological performance may be weak or undetectable. Furthermore, intraspecific variation in both structural and physiological traits leads to differences in plant size and fitness. These results demonstrate the importance of considering measurements of multivariate phenotypes on individual plants when evaluating trait relationships and how trait variation influences predictions of ecological and evolutionary outcomes.