Females restrict the position of domatia and suffer more herbivory than hermaphrodites in Myriocarpa longipes, a neotropical facultative myrmecophyte

Domatia are hollow structures in plants occupied by ant colonies, in turn ants provide protection against herbivores. In plants, competition for resources has driven sex-related changes in the patterns of resource allocation to life-history traits and defence traits. The resource-competition hypothesis (RCH) proposes that female plants due to their higher investment in reproduction will allocate fewer resources to defence production, showing greater herbivore damage than other sexual forms. We hypothesise the existence of sex-related differences in defensive traits of domatia-bearing plants, being female plants less defended due to differences in domatia traits, such as size, number of domatia and their position, exhibiting more herbivore damage than hermaphrodite plants of Myriocarpa longipes, a facultative neotropical myrmecophyte. We found eight species of ants inhabiting domatia; some species co-inhabited the same plant, even the same branch. Our results are consistent with the predictions of RCH, as female plants had ant-inhabited domatia restricted to the middle position of their branches and exhibited greater herbivore damage in leaves than hermaphrodites. However, we did not find differences in domatia size and leaf area between sexual forms. Our study provides evidence for intersexual differences in domatia position and herbivory in a facultative ant–plant mutualism in M. longipes. We highlight the importance of considering the plant sex in ant–plant interactions. Differences in resource allocation related to sexual reproduction could influence the outcome of ant–plant interactions.

Impact of the female and hermaphrodite forms of Opuntia robusta on the plant defence hypothesis

The optimal defence hypothesis predicts that increased plant defence capabilities, lower levels of damage, and lower investment in vegetative biomass will occur more frequently in sexual forms with higher resource-demanding tissue production and/or younger plant parts. We aimed to examine the effects of sexual form, cladode, and flower age on growth rate, herbivore damage, and 4-hydroxybenzoic acid (4-HBA), chlorogenic acid, and quercetin (QUE) concentrations in Opuntia robusta plants in central Mexico. Our findings demonstrated that hermaphrodite flowers showed faster growth and lesser damage than female flowers. The effect of cladode sexual forms on 4-HBA and QUE occurrence was consistent with the predictions of the optimal defence hypothesis. However, chlorogenic acid occurrences were not significantly affected by sexual forms. Old cladodes exhibited higher QUE and 4-HBA occurrences than young cladodes, and hermaphrodites exhibited higher 4-HBA concentrations than females. Resource allocation for reproduction and secondary metabolite production, and growth was higher and lower, respectively, in females, compared to hermaphrodites, indicating a trade-off between investment in reproduction, growth, and secondary metabolite production. Secondary metabolite concentrations in O. robusta plants were not negatively correlated with herbivore damage, and the two traits were not accurate predictors of plant reproductive output.

Adult body growth and reproductive investment vary markedly within and across Atlantic and Pacific herring: a meta-analysis and review of 26 stocks

Life-history traits of Pacific (Clupea pallasii) and Atlantic (Clupea harengus) herring, comprising both local and oceanic stocks subdivided into summer-autumn and spring spawners, were extensively reviewed. The main parameters investigated were body growth, condition, and reproductive investment. Body size of Pacific herring increased with increasing latitude. This pattern was inconsistent for Atlantic herring. Pacific and local Norwegian herring showed comparable body conditions, whereas oceanic Atlantic herring generally appeared stouter. Among Atlantic herring, summer and autumn spawners produced many small eggs compared to spring spawners, which had fewer but larger eggs—findings agreeing with statements given several decades ago. The 26 herring stocks we analysed, when combined across distant waters, showed clear evidence of a trade-off between fecundity and egg size. The size-specific individual variation, often ignored, was substantial. Additional information on biometrics clarified that oceanic stocks were generally larger and had longer life spans than local herring stocks, probably related to their longer feeding migrations. Body condition was only weakly, positively related to assumingly in situ annual temperatures (0–30 m depth). Contrarily, body growth (cm × y−1), taken as an integrator of ambient environmental conditions, closely reflected the extent of investment in reproduction. Overall, Pacific and local Norwegian herring tended to cluster based on morphometric and reproductive features, whereas oceanic Atlantic herring clustered separately. Our work underlines that herring stocks are uniquely adapted to their habitats in terms of trade-offs between fecundity and egg size whereas reproductive investment mimics the productivity of the water in question.

Synthesis and Outlook

In this final chapter I want to briefly recap what I presented in the previous chapters and provide a few ideas on what might be done in the future to move the field forward. All three factors I discussed as relevant in male mate choice—male investment in reproduction, sex ratios, and variability in partner quality—are still emerging fields in sexual selection research and need more theoretical and empirical work. I suggest that variability in female quality is more important and more complex than currently known. The same is true for sex ratios. On the other hand, I suggest that sheer investment in gametes may be a little less important than currently assumed. Most importantly we need to explore the interactions of these three pathways to male mate choice. Female competition and also female ornamentation are still somewhat enigmatic and both topics are likely to grow in importance for our understanding of sexual selection. I think considering male and female choice together, as well as female and male competition will ultimately provide a more complete picture of Darwinian sexual selection.

Exaptation Traits for Megafaunal Mutualisms as a Factor in Plant Domestication

Megafaunal extinctions are recurring events that cause evolutionary ripples, as cascades of secondary extinctions and shifting selective pressures reshape ecosystems. Megafaunal browsers and grazers are major ecosystem engineers, they: keep woody vegetation suppressed; are nitrogen cyclers; and serve as seed dispersers. Most angiosperms possess sets of physiological traits that allow for the fixation of mutualisms with megafauna; some of these traits appear to serve as exaptation (preadaptation) features for farming. As an easily recognized example, fleshy fruits are, an exaptation to agriculture, as they evolved to recruit a non-human disperser. We hypothesize that the traits of rapid annual growth, self-compatibility, heavy investment in reproduction, high plasticity (wide reaction norms), and rapid evolvability were part of an adaptive syndrome for megafaunal seed dispersal. We review the evolutionary importance that megafauna had for crop and weed progenitors and discuss possible ramifications of their extinction on: (1) seed dispersal; (2) population dynamics; and (3) habitat loss. Humans replaced some of the ecological services that had been lost as a result of late Quaternary extinctions and drove rapid evolutionary change resulting in domestication.

MANAGEMENT OF INTELLECTUAL CAPITAL DEVELOPMENT OF THE ENTERPRISE WITH ORIENTATION ON THE PURPOSE, POSSIBILITIES, EFFICIENCY AND INNOVATION

The work is devoted to the substantiation of the system of management decisions to increase the level of development of intellectual capital of the enterprise as a whole and its individual components with a focus on goals, opportunities, efficiency and innovation. Determined following criteria for selection of measures to increase the level of development of certain types of intellectual capital of the enterprise: the size of vertical development reserves, the size of horizontal development reserves, the efficiency of investment in reproduction. Economic and statistical tools are recommended to formalize the task of forming a system of measures taking into account determined criteria. Approaches to setting thresholds for selection criteria depending on the characteristics of the internal and external environment of the enterprise, management targets are proposed. The expediency of checking the implemented measures for pareto-optimality in order to prevent the implementation of measures that will have a negative impact on the development of certain types of intellectual capital of the enterprise is revealed. The expediency of using the cost of reproduction of intellectual capital of the enterprise as an indicator of investment efficiency is substantiated. Proposed to use single-criteria optimization for the selection of specific measures on the principle of the highest cost effectiveness for their implementation. The structural and logical model of achieving the target settings of intellectual capital development management of the enterprise, which takes into account internal and external conditions, management objectives and results of performance evaluation, levels and reserves of intellectual capital development and its components, is presented in six stages. A system of standard measures to increase the level of development of certain components of the intellectual capital of the enterprise is recommended.

Faecal parasites increase with age but not reproductive effort in wild female chimpanzees

Energy investment in reproduction is predicted to trade off against other necessary physiological functions like immunity, but it is unclear to what extent this impacts fitness in long-lived species. Among mammals, female primates, and especially apes, exhibit extensive periods of investment in each offspring. During this time, energy diverted to gestation and lactation is hypothesized to incur short and long-term deficits in maternal immunity and lead to accelerated ageing. We examined the relationship between reproduction and immunity, as measured by faecal parasite counts, in wild female chimpanzees ( Pan troglodytes schweinfurthii ) of Kibale National Park, Uganda. While we observed higher parasite shedding (counts of eggs, cysts and larvae) in pregnant chimpanzees relative to cycling females, parasites rapidly decreased during early lactation, the most energetically taxing phase of the reproductive cycle. Additionally, while our results indicate that parasite shedding increases with age, females with higher fertility for their age had lower faecal parasite counts. Such findings support the hypothesis that the relatively conservative rate of female reproduction in chimpanzees may be protective against the negative effects of reproductive effort on health. This article is part of the theme issue ‘Evolution of the primate ageing process’.

Animal Personality and Investment in Reproduction: Hermit Crabs and Other Crustaceans as Model Organisms

Animal personality has been demonstrated in a wide range of taxa, including crustaceans. This chapter defines personality as consistent variation in behavior among individuals. It describes related ideas about how individuals can differ in the way they adjust their behavior to match the current situation (“behavioral plasticity”) and how they might differ in how consistent their behavior is within a particular situation (“within individual variation”). Such behavioral variation may represent a component of wider syndromes encompassing among-individual differences in life history traits such as growth, metabolism, and fecundity. First, the chapter reviews studies that have tested these ideas in a range of crustacean species. It then focuses on a series of studies on the common European hermit crab Pagurus bernhardus. In both cases, it describes details of the experimental approaches and analyses used to study personality in crustaceans. While boldness appears to be a key personality trait in hermit crabs and other crustaceans, bold individuals are not necessarily those with the greatest success in acquiring resources or with the greatest life history productivity (i.e., investment in growth and reproduction). Rather, individuals that win fights and invest heavily in respiratory pigments and in reproduction appear to behave consistently more cautious when compared to other individuals from the same population. Despite these initial findings, there is a paucity of studies that investigate links between personality and mating behavior in crustaceans, or that investigate the behavior of females; these areas should be priorities for future work.