Does inbreeding affect personality traits?

The question of why variation is maintained in personality traits is an evolutionary puzzle. According to the condition‐dependence hypothesis, such traits depend on condition, which limits the behavioral choices available to individuals. Because condition is affected by many genes, it can effectively be manipulated by inbreeding, which exposes the effects of deleterious recessive mutations. Here, I compared two personality traits, boldness and tendency to explore, of male guppies (Poecilia reticulata) from first‐generation inbred and outbred treatments. Boldness in guppies is associated with increased sexual attractiveness and is thus expected to affect fitness. Therefore, I hypothesized that the personality traits would be negatively affected by inbreeding. However, the results indicated that inbred guppies did not differ in either personality trait from their outbred counterparts. This finding suggests that mechanisms other than condition dependence are maintaining personality variation in the guppy.     

Do early branching lineages signify ancestral traits?

A reverence for ancestors that has pre-occupied humans since time immemorial persists to the present. Reconstructing ancestry is the focus of many biological studies but failure to distinguish between present-day descendants and long-dead ancestors has led to incorrect interpretation of phylogenetic trees. This has resulted in erroneous reconstruction of traits such as morphology and ancestral areas. Misinterpretation becomes evident when authors use the terms 'basal' or 'early diverging' to refer to extant taxa. Here, we discuss the correct interpretation of trees and methods for reconstructing the ancestral features of organisms using recently developed statistical models. These models can be inaccurate unless they use information that is independent of phylogenies, such as genetics, molecular and developmental biology, functional morphology, geological and climatic processes, and the fossil record.     

Can tolerance traits impose selection on herbivores?

Plant tolerance reduces the fitness consequences of herbivore and natural enemy damage, while resistance reduces the amount of damage suffered. In contrast to resistance, tolerance is often assumed to not affect herbivore performance and evolution. Evidence from the literature, however, suggests that it is possible for plant tolerance to affect herbivore performance and evolution, and potentially plant–herbivore coevolution. First, for cases when genetic correlations between resistance and tolerance are due to pleiotropy, the genes and loci for tolerance and resistance are the same, and as such both traits will affect herbivore performance directly. Second, it is possible that the physiological basis and mechanisms of plant tolerance – for example, changes in plant physiology and resource allocation – directly alter herbivore fitness characters. In this paper, I review the evidence for these potential effects of plant tolerance on herbivore performance, and suggest straightforward experiments to evaluate these possibilities. More generally, I propose that this untested assumption is constraining our view of plant–herbivore coevolution.     

Why are behavioral and immune traits linked?

Through behavior, animals interact with a world where parasites abound. It is easy to understand how behavioral traits can thus have a differential effect on pathogen exposure. Harder to understand is why we observe behavioral traits to be linked to immune defense traits. Is variation in immune traits a consequence of behavior-induced variation in immunological experiences? Or is variation in behavioral traits a function of immune capabilities? Is our immune system a much bigger driver of personality than anticipated? In this review, I provide examples of how behavioral and immune traits co-vary. I then explore the different routes linking behavioral and immune traits, emphasizing on the physiological/hormonal mechanisms that could lead to immune control of behavior. Finally, I discuss why we should aim at understanding more about the mechanisms connecting these phenotypic traits.     

Do parasitic common goldeneye Bucephala clangula females choose nests on the basis of host traits or nest site traits?

Conspecific brood parasitism (CBP) is an important alternative breeding strategy for gaining reproductive output in birds. While interactions between hosts and parasites and consequences of CBP to breeding success of both parties have been studied a lot, the roles of host characteristics and nest site characteristics in CBP have received less attention. We studied the relative importance of host‐related traits, such as female condition and breeding experience, and nest‐site‐related factors, such as overall nest site preference and occupation rate, in explaining the occurrence of CBP in a common goldeneye Bucephala clangula population. We used spatially and temporally extensive data sets, analysed the data with generalized linear mixed models that allowed us to account for the non‐independency of individual nesting attempts across females and nesting sites, and used an information theoretic approach in model selection and inference. About half of the nests were parasitized annually during the seven year study period. The occurrence of CBP decreased with advancement of the breeding season but late nests were also frequently parasitized. We found that the occurrence of CBP was better explained by nest‐site characteristics than host traits, implying that parasitic females target a given nest based on factors related to the nest site itself rather than on the host. Our results suggest that more attention should be paid to factors associated with nest site attractiveness and quality when studying laying decisions of parasites and the occurrence of CBP in general.     

Are secondary sex traits, parasites and immunity related to variation in primary sex traits in the Arctic charr?

Primary and secondary sex traits are influenced by the same sex hormones, and the expression of secondary sex traits may consequently signal males' capacity for sperm production. Sperm quality may also be influenced by immune activity, as sperm are non-self to the male. Parasite infections alter immune activity and may thus reduce ejaculate quality. In the Arctic charr (Salvelinus alpinus) the red abdominal colour is considered an ornament that signals important information in mate choice. We captured and individually caged sexually mature male Arctic charr during the spawning period. Afterwards we estimated abdominal colour, parasite infections, gonad mass and several spermatological and immunological variables. Intensity of abdominal colour was positively correlated to testes mass, milt mass and sperm cell numbers produced. Additionally, males with low parasite intensities had high testes mass and produced milt with high sperm density, indicating a trade-off between parasite resistance and development of primary sex traits. Our measures of immunity were, however, not related to primary sex traits. We conclude that females evaluating male abdominal coloration may obtain information about differences between males in fertilization potential and parasite resistance.     

Detecting QTL for feed intake traits and other performance traits in growing pigs in a Piétrain-Large White backcross

Knowing the large difference in daily feed intake (DFI) between Large White (LW) and Piétrain (PI) growing pigs, a backcross (BC) population has been set up to map QTL that could be used in marker assisted selection strategies. LW × PI boars were mated with sows from two LW lines to produce 16 sire families. A total of 717 BC progeny were fed ad libitum from 30 to 108 kg BW using single-place electronic feeders. A genome scan was conducted using genotypes for the halothane gene and 118 microsatellite markers spread on the 18 porcine autosomes. Interval mapping analyses were carried out, assuming different QTL alleles between sire families to account for within breed variability using the QTLMap software. The effects of the halothane genotype and of the dam line on the QTL effect estimates were tested. One QTL for DFI (P < 0.05 at the chromosome-wide (CW) level) and one QTL for feed conversion ratio (P < 0.01 at the CW level) were mapped to chromosomes SSC6 - probably due to the halothane alleles - and SSC7, respectively. Three putative QTL for feed intake traits were detected (P < 0.06 at the CW level) on SSC2, SSC7 and SSC9. QTL on feeding traits had effects in the range of 0.20 phenotypic s.d. The relatively low number of QTL detected for these traits suggests a large QTL allele variability within breeds and/or low effects of individual loci. Significant QTL were detected for traits related to carcass composition on chromosomes SSC6, SSC15 and SSC17, and to meat quality on chromosome SSC6 (P < 0.01 at the genome-wide level). QTL effects for body composition on SSC13 and SSC17 differed according to the LW dam line, which confirmed that QTL alleles were segregating in the LW breed. An epistatic effect involving the halothane locus and a QTL for loin weight on SSC7 was identified, the estimated substitution effects for the QTL differing by 200 g between Nn and NN individuals. The interactions between QTL alleles and genetic background or particular genes suggest further work to validate QTL segregations in the populations where marker assisted selection for the QTL would be applied.     

Analysis of genetic effects of nuclear–cytoplasmic interaction on quantitative traits: Genetic models for seed traits of plants

Two Genetic models (an embryo model and an endosperm model) were proposed for analyzing genetic effects of nuclear genes, cytoplasmic genes, maternal genes, and nuclear–cytoplasmic interaction (NCI) as well as their genotype by environment interaction for quantitative traits of plant seed. In these models, the NCI effects were partitioned into direct additive and dominance NCI components. Mixed linear model approaches were employed for statistical analysis. For both balanced and unbalanced diallel cross designs, Monte Carlo simulations were conducted to evaluate unbiasedness and precision of estimated variance components of these models. The results showed that the proposed methods work well. Random genetic effects were predicted with an adjusted unbiased prediction method. Seed traits (protein content and oil content) of Upland cotton (Gossypium hirsutum L.) were analyzed as worked examples to demonstrate the use of the models.     

Do host bark traits influence trunk epiphyte communities?

Host bark traits are known to affect the characteristics of epiphyte communities in forests worldwide; however, few investigations of such relationships have been undertaken in New Zealand forests. By examining the trunk epiphyte communities on four co-occurring forest tree species (Agathis australis, Dacrydium cupressinum, Knightia excelsa and Vitex lucens) representing a range of bark characteristics, we sought evidence that bark traits may shape these communities. Sampling was conducted on tree trunks in the Waitakere and Hunua ranges in the Auckland Region. As expected, the rough but lightly shedding bark of Vitex lucens was found to support many epiphytes, whereas the coarsely flaking bark surface of Dacrydium cupressinum supported few epiphytes. Conversely, despite bark with a smooth texture that sheds in large flakes, and contrary to the suggestions of previous authors, Agathis australis trunks were found to support the greatest numbers of epiphytes and this species was one of the most frequent epiphyte hosts. The individual epiphytes found on Agathis australis, however, were significantly smaller and more appressed to the trunk than those on the other trees, and species composition differed from the other host species.     

Are animal personality traits linked to life-history productivity?

Animal personality traits such as boldness, activity and aggressiveness have been described for many animal species. However, why some individuals are consistently bolder or more active than others, for example, is currently obscure. Given that life-history tradeoffs are common and known to promote inter-individual differences in behavior, we suggest that consistent individual differences in animal personality traits can be favored when those traits contribute to consistent individual differences in productivity (growth and/or fecundity). A survey of empirical studies indicates that boldness, activity and/or aggressiveness are positively related to food intake rates, productivity and other life-history traits in a wide range of taxa. Our conceptual framework sets the stage for a closer look at relationships between personality traits and life-history traits in animals.     

Expression of embryonic hemoglobin genes in mice heterozygous for α-thalassemia or β-duplication traits and in mice heterozygous for both traits

Hemoglobins of mouse embryos at 11.5 through 16.5 days of gestation were separated by electrophoresis on cellulose acetate and quantitated by a scanning densitometer to study the effects of two radiation-induced mutations on the expression of embryonic hemoglobin genes in mice. Normal mice produce three kinds of embryonic hemoglobins. In heterozygous α-thalassemic embryos, expression of EI (x₂y₂) and EII (α₂y₂) is deficient because the x- and α-globin genes of one of the allelic pairs of Hba on chromosome 11 was deleted or otherwise inactivated by X irradiation. Simultaneous inactivation of the x- and α-globin genes indicates that these genes must be closely linked. Reduced x- and α-chain synthesis results in an excess of y chains that associate as homotetramers. This unique y₄ hemoglobin also appears in β-duplication embryos where excess y chains are produced by the presence of three rather than two functional alleles of y- and β-globin genes. In double heterozygotes, which have a single functional allele of x- and α-globin genes and three functional alleles of y- and β-globin genes, synthesis of α and non-α chains is severely imbalanced and half of the total hemoglobin is y₄. Mouse y₄ has a high affinity for oxygen, P₅₀ of less than 10 mm Hg, but it lacks cooperativity so is inefficient for oxygen transport. The death of double heterozygotes in late fetal or neonatal life may be due in large part to oxygen deprivation to the tissues.     

Are plasticity in functional traits and constancy in performance traits linked with invasiveness? An experimental test comparing invasive and naturalized plant species

The role of phenotypic plasticity in plant invasions is among the most often discussed relationships in invasion ecology. However, despite the large number of studies on this topic, there is little consistency. Reconsideration of the role of plasticity by distinguishing two substantially distinct trait-groups, performance traits (contributing directly to fitness) and functional traits (influencing fitness indirectly), could form a more operative framework for comparative studies. In the current study we expect that invasive species benefit from being plastic in functional traits, which allows them to maintain a more constant performance across different environmental conditions compared to non-invasive alien species. We compared invasive and naturalized non-invasive alien plant species by their germination (20 species), their vegetative (10 species) and their reproductive (four species) responses to three different levels of water, light and nutrient availability in a common garden experiment. Used traits were classified into performance (germination ratio, total biomass, seed number) and functional traits (time to germination, root:shoot ratio, specific leaf area, reproductive allocation). We found that invasive and non-invasive species responded similarly to environmental factors, except for example that invasive species germinated earlier with decreasing light conditions or, surprisingly, non-invasive species reacted more intensely to increased nitrogen availability by having a superior ability to achieve greater biomass. The two groups were equally plastic in all the germination and vegetative traits measured but the reproductive traits, since higher plasticity in relative reproductive allocation and higher constancy in reproductive performance showed a pronounced relation with invasiveness.     

Haemoglobin synthesis in 28 obligatory cases for α-thalassemia traits

Summary In the Far East two types of -thalassemia genes, namely -thalassemia₁ (-thal₁) and -thalassemia₂ (-thal₂) exist. Definite diagnosis of the -thal₁ and -thal₂ traits is very difficult because their hematological findings are minimally abnormal or normal. This study attempts to characterize the heterozygotes by hemoglobin chain synthesis in reticulocytes from obligatory cases of the -thal₁ and -thal₂ traits. Twelve parents of babies with hemoglobin Bart's hydrops fetalis (obligatory -thal₁ trait) had the mean total radioactivity / ratio of 0.76±SD 0.04, while that of 7 normal controls was 1.06±SD 0.04. The / globin chain ratios of 16 cases, who were either parents or offspring of patients with hemoglobin H disease, were found to segregate into 2 groups, i.e. 0.78±SD 0.03 (10 cases) and 0.92±SD 0.03 (6 cases), probably representing the -thal₁ and -thal₂ traits respectively. The hematological data of the first group showed definite hypochromic microcytic red cells, similar to thoseof the parents of the hydrops. The second group had significantly higher mean corpuscular hemoglobin than the first group, compatible with -thal₂ trait. Our globin chain synthesis study thus appears to be capable of discriminating normal, -thal₁ and -thal₂ traits.A preliminary report of the results was presented at the XV Congress of the International Society of Haematology, Israel, September, 1974.     

Cyclic variation in women’s preferences for masculine traits

Women’s preferences for several male traits, including voices, change over the menstrual cycle, but the proximate causes of these changes are unknown. This paper explores relationships between levels of estradiol, progesterone, luteinizing hormone, follicle stimulating hormone, prolactin, and testosterone (estimated using menstrual cycle information) and women’s preferences for male vocal masculinity in normally cycling and hormonally contracepting heterosexual females. Preferences for vocal masculinity decreased with predicted progesterone levels and increased with predicted prolactin levels in normally cycling—but not hormonally contracepting—women. Adaptive explanations for menstrual variation in women’s preferences for masculine traits are discussed and evaluated in light of these findings.     

Are we underestimating the genetic variances of dimorphic traits?

Populations often contain discrete classes or morphs (e.g., sexual dimorphisms, wing dimorphisms, trophic dimorphisms) characterized by distinct patterns of trait expression. In quantitative genetic analyses, the different morphs can be considered as different environments within which traits are expressed. Genetic variances and covariances can then be estimated independently for each morph or in a combined analysis. In the latter case, morphs can be considered as separate environments in a bivariate analysis or entered as fixed effects in a univariate analysis. Although a common approach, we demonstrate that the latter produces downwardly biased estimates of additive genetic variance and heritability unless the quantitative genetic architecture of the traits concerned is perfectly correlated between the morphs. This result is derived for four widely used quantitative genetic variance partitioning methods. Given that theory predicts the evolution of genotype‐by‐environment (morph) interactions as a consequence of selection favoring different trait combinations in each morph, we argue that perfect correlations between the genetic architectures of the different morphs are unlikely. A sampling of the recent literature indicates that the majority of researchers studying traits expressed in different morphs recognize this and do estimate morph‐specific quantitative genetic architecture. However, ca. 16% of the studies in our sample utilized only univariate, fixed‐effects models. We caution against this approach and recommend that it be used only if supported by evidence that the genetic architectures of the different morphs do not differ.     

Can population genetic structure be predicted from life-history traits?

Population genetic structure is a key parameter in evolutionary biology. Earlier comparative studies have shown that genetic structure depends on species ecological attributes and life-history traits, but species phylogenetic relatedness had not been accounted for. Here we reevaluate the relationships between genetic structure and species traits in seed plants. Each species is characterized by a set of life-history and ecological features as well as by its geographic range size, its heterozygote deficit, and its genetic structure at nuclear and organelle markers to distinguish between pollen- and seed-mediated gene flow. We use both a conventional regression approach and a method that controls for phylogenetic relationships. Once phylogenetic conservatism and covariation among traits are taken into account, genetic structure is shown to be related with only a few synthetic traits, such as mating system for nuclear markers and seed dispersal mode or geographic range size for organelle markers. Along with other studies on invasiveness or rarity, our work illustrates the fact that predicting the fate of species across a broad taxonomic assemblage on the basis of simple traits is rarely possible, a testimony of the highly contingent nature of evolution.     

Magic traits in speciation: 'magic' but not rare?

Speciation with gene flow is greatly facilitated when traits subject to divergent selection also contribute to non-random mating. Such traits have been called 'magic traits', which could be interpreted to imply that they are rare, special, or unrealistic. Here, we question this assumption by illustrating that magic traits can be produced by a variety of mechanisms, including ones in which reproductive isolation arises as an automatic by-product of adaptive divergence. We also draw upon the theoretical literature to explore whether magic traits have a unique role in speciation or can be mimicked in their effects by physically linked trait-complexes. We conclude that magic traits are more frequent than previously perceived, but further work is needed to clarify their importance.     

Can metabolic traits explain animal community assembly and functioning?

All animals on Earth compete for free energy, which is acquired, assimilated, and ultimately allocated to growth and reproduction. Competition is strongest within communities of sympatric, ecologically similar animals of roughly equal size (i.e. horizontal communities), which are often the focus of traditional community ecology. The replacement of taxonomic identities with functional traits has improved our ability to decipher the ecological dynamics that govern the assembly and functioning of animal communities. Yet, the use of low-resolution and taxonomically idiosyncratic traits in animals may have hampered progress to date. An animal's metabolic rate (MR) determines the costs of basic organismal processes and activities, thus linking major aspects of the multifaceted constructs of ecological niches (where, when, and how energy is obtained) and ecological fitness (how much energy is accumulated and passed on to future generations). We review evidence from organismal physiology to large-scale analyses across the tree of life to propose that MR gives rise to a group of meaningful functional traits – resting metabolic rate (RMR), maximum metabolic rate (MMR), and aerobic scope (AS) – that may permit an improved quantification of the energetic basis of species coexistence and, ultimately, the assembly and functioning of animal communities. Specifically, metabolic traits integrate across a variety of typical trait proxies for energy acquisition and allocation in animals (e.g. body size, diet, mobility, life history, habitat use), to yield a smaller suite of continuous quantities that: (1) can be precisely measured for individuals in a standardized fashion; and (2) apply to all animals regardless of their body plan, habitat, or taxonomic affiliation. While integrating metabolic traits into animal community ecology is neither a panacea to disentangling the nuanced effects of biological differences on animal community structure and functioning, nor without challenges, a small number of studies across different taxa suggest that MR may serve as a useful proxy for the energetic basis of competition in animals. Thus, the application of MR traits for animal communities can lead to a more general understanding of community assembly and functioning, enhance our ability to trace eco-evolutionary dynamics from genotypes to phenotypes (and vice versa), and help predict the responses of animal communities to environmental change. While trait-based ecology has improved our knowledge of animal communities to date, a more explicit energetic lens via the integration of metabolic traits may further strengthen the existing framework.