Evolution of Social Learning with Payoff and Content Bias

There has been much theoretical work aimed at understanding the evolution of social learning; and in most of it, individual and social learning are treated as distinct processes. A number of authors have argued that this approach is faulty because the same psychological mechanisms underpin social and individual learning. In previous work, we analyzed a simple model in which both individual and social learning are the result of a single learning process. Here, we extend this approach by showing how payoff and content biases evolve. We show that payoff bias leads to higher average fitness when environments are noisy and change rapidly. Content bias always evolves when the expected fitness benefits of alternative traits differ.

Female Reproductive Strategies and the Ovarian Cycle in Hamadryas Baboons

<p>This thesis examines the relationship between sexual behaviour and the ovarian cycle in a group-living primate, Papio h. hamadryas. Of particular interest is whether females modify their ovarian cycle in a manner that is expected increase their reproductive success. The study was conducted on a captive colony where the resident males (RM) had been vasectomised prior to start of the study resulting in all mature females undergoing repeated ovarian cycling throughout the study period. This made the analysis of sexual behaviour relative to fine scale changes in the ovarian cycle possible. One year of ovarian cycle data and 280 hours of behavioural data was collected via observational sampling during the study. RM vasectomisation did not alter the archetypal one male unit social structure nor the typical socio-spatial organisation of wild hamadryas populations. Females were found to be more promiscuous than in wild populations, however, presumably because of the confounding effect that the high number of simultaneously cycling females had on RM herding (Chapter 1). RMs dominated copulations over the optimal conceptive period of the ovarian cycle, while the majority of extra-OMU copulations occurred outside this period and were rarely solicited by females. This pattern supports a dual paternity concentration/paternity confusion strategy, and not female choice or fertility insurance strategies (Chapter 2). Females were not found to synchronise or asynchronise their cycles over the 1 year study period, although a review of the literature on hamadryas breeding patterns suggests that they may be able to do so over shorter periods (Chapter 3). Females did, however, appear to regulate the length of the turgescent phase of their ovarian cycle in a manner that would facilitate a paternity confusion strategy and maximise their expected fitness payoff (Chapter 4). Consequently, this study provides empirical evidence that female hamadryas baboons manipulate their ovarian cycle in a manner that is expected to increase their reproductive success.</p>

Female Reproductive Strategies and the Ovarian Cycle in Hamadryas Baboons

<p>This thesis examines the relationship between sexual behaviour and the ovarian cycle in a group-living primate, Papio h. hamadryas. Of particular interest is whether females modify their ovarian cycle in a manner that is expected increase their reproductive success. The study was conducted on a captive colony where the resident males (RM) had been vasectomised prior to start of the study resulting in all mature females undergoing repeated ovarian cycling throughout the study period. This made the analysis of sexual behaviour relative to fine scale changes in the ovarian cycle possible. One year of ovarian cycle data and 280 hours of behavioural data was collected via observational sampling during the study. RM vasectomisation did not alter the archetypal one male unit social structure nor the typical socio-spatial organisation of wild hamadryas populations. Females were found to be more promiscuous than in wild populations, however, presumably because of the confounding effect that the high number of simultaneously cycling females had on RM herding (Chapter 1). RMs dominated copulations over the optimal conceptive period of the ovarian cycle, while the majority of extra-OMU copulations occurred outside this period and were rarely solicited by females. This pattern supports a dual paternity concentration/paternity confusion strategy, and not female choice or fertility insurance strategies (Chapter 2). Females were not found to synchronise or asynchronise their cycles over the 1 year study period, although a review of the literature on hamadryas breeding patterns suggests that they may be able to do so over shorter periods (Chapter 3). Females did, however, appear to regulate the length of the turgescent phase of their ovarian cycle in a manner that would facilitate a paternity confusion strategy and maximise their expected fitness payoff (Chapter 4). Consequently, this study provides empirical evidence that female hamadryas baboons manipulate their ovarian cycle in a manner that is expected to increase their reproductive success.</p>

Hutchinson's ecological niche for individuals

We here develop a concept of an individualized niche in analogy to Hutchison’s concept of the ecological niche of a population. We consider the individualized (ecological) niche as the range of environmental conditions under which a particular individual has a fitness expectation of ≥1. We address four specific challenges that occur when scaling the niche down from populations to individuals: (1) We discuss the consequences of uniqueness of individuals in a population and the corresponding lack of statistical replication. (2) We discuss the dynamic nature of individualized niches and how they can be studied either as time-slice niches, as prospective niches or as trajectory-based niches. (3) We discuss the dimensionality of the individualized niche, that is greater than the population niche due to the additional dimensions of intra-specific niche space. (4) We discuss how the boundaries of individualized niche space can to be defined by expected fitness and how expected fitness can be inferred by marginalizing fitness functions across phenotypes or environments. We frame our discussion in the context of recent interest in the causes and consequences of individual differences in animal behavior.

Development of Multiple Behaviors in Evolving Robots

We investigate whether standard evolutionary robotics methods can be extended to support the evolution of multiple behaviors by forcing the retention of variations that are adaptive with respect to all required behaviors. This is realized by selecting the individuals located in the first Pareto fronts of the multidimensional fitness space in the case of a standard evolutionary algorithms and by computing and using multiple gradients of the expected fitness in the case of a modern evolutionary strategies that move the population in the direction of the gradient of the fitness. The results collected on two extended versions of state-of-the-art benchmarking problems indicate that the latter method permits to evolve robots capable of producing the required multiple behaviors in the majority of the replications and produces significantly better results than all the other methods considered.

Birth order as a source of within-genotype diversification in the clonal duckweed, Spirodela polyrhiza (Araceae: Lemnoideae)

Organismal persistence attests to adaptive responses to environmental variation. Diversification bet hedging, in which risk is reduced at the cost of expected fitness, is increasingly recognized as an adaptive response, yet mechanisms by which a single genotype generates diversification remain obscure. The clonal greater duckweed, Spirodela polyrhiza (L.), facultatively expresses a seed-like but vegetative form, the ‘turion’, that allows survival through otherwise lethal conditions. Turion reactivation phenology is a key fitness component, yet little is known about turion reactivation phenology in the field, or sources of variation. Here, using floating traps deployed in the field, we found a remarkable extent of variation in natural reactivation phenology that could not be explained solely by spring cues, occurring over a period of ≥ 200 days. In controlled laboratory conditions, we found support for the hypothesis that turion phenology is influenced jointly by phenotypic plasticity to temperature and diversification within clones. Turion ‘birth order’ consistently accounted for a difference in reactivation time of 46 days at temperatures between 10 and 18 °C, with turions early in birth order reactivating more rapidly than turions late in birth order. These results should motivate future work to evaluate the variance in turion phenology formally as a bet-hedging trait.

Reliability Analysis of Technical Means of Transport

The importance of system reliability within military logistics should be considered in terms of the ability to ensure the readiness of all available resources, e.g., means of transport, which are necessary during the realization of operational tasks. A special role is played by technical security, which enables the performance of all the specific tasks by the realization of the process supporting the subsystem in the area of providing the necessary assemblies, subassemblies and spare parts. The objective of the work was to define reliability in relation to technical means of transport and to illustrate an original solution leading to the determination of the expected fitness time of the available vehicle fleet, using the example of a selected military unit. The GNU Octave software—designed to conduct, among other things, advanced numerical computations—was used for the study. The daily operational mileage for a selected group of means of transport and the moments of failures were recorded during the tests, for the period from 31 December 2013 until 30 June 2015. The conducted analysis enabled the determination of the fundamental reliability indicators. The presented model has been supported with numerical examples, along with the interpretation of the obtained results.

Why men invest in non-biological offspring: paternal care and paternity confidence among Himba pastoralists

Paternal investment is predicted to be a facultative calculation based on expected fitness returns and modulated by a host of social predictors including paternity uncertainty. However, the direct role of paternity confidence on the patterns of paternal investment is relatively unknown, in part due to a lack of research in populations with high levels of paternity uncertainty. Additionally, much of the work on paternity certainty uses cues of paternity confidence rather than direct assessments from fathers. We examine the effect of paternity assertions on the multiple measures of paternal investment in Himba pastoralists. Despite a high degree of paternity uncertainty, Himba have strong norms associated with social fatherhood, with men expected to invest equally in biological and non-biological offspring. Our behavioural data show patterns that largely conform to these norms. For domains of investment that are highly visible to the community, such as brideprice payments, we find no evidence of investment biased by paternity confidence. However, more private investment decisions do show some evidence of sex-specific titration. We discuss these results in light of broader considerations about paternal care and the mating–parenting trade-off.

Fruit-feeding in European cold season noctuid moths increases fecundity, but not longevity

Feeding on rotting fruits, rather than nectar, is linked to high adult life-expectancy in certain butterflies, notably tropical Nymphalidae. We experimentally tested whether cold-season central European noctuid moths may also derive longevity and fecundity benefits from feeding on fruits. Many cold-season noctuid moths avidly feed on such resources. We expected fitness benefits to be especially pronounced in moths which overwinter as adults, in relation to their unusually long and thus nutrient-demanding imaginal life (6–9 months). Field-caught female individuals representing four genera (Allophyes Tams, 1942; Agrochola Hübner, 1821; Conistra Hübner, 1821; Eupsilia Hübner, 1821) were offered sucrose solution, sucrose solution enriched with vitamins, or moisturized banana slices plus sucrose solution, respectively, under greenhouse conditions. These moths represented two life-cycle types (autumn species vs. adult hibernators). Life span differed between moth genera, but we did not observe any enhancement of life span through fruit-feeding. Rather, in some cases moths kept with access to banana slices experienced a minor reduction in life span, compared to moths fed sucrose solution only. We observed no benefits in terms of enhanced fecundity through fruit-feeding in autumn species. Among adult hibernators, in contrast, potential fecundity increased by over 50% in banana-fed females, when observed over their full lifetime. Yet, if kept in the lab only after completing their hibernation in the wild, fitness benefits no longer accrued to moths from supplementing their diet with fruits. We conclude that noctuids that hibernate as adults are indeed income breeders which potentially increase their fecundity by feeding on fruits.