Generalization of learned preferences covaries with behavioral flexibility in red junglefowl chicks

2019. Josefina Zidar (et al.). Behavioral Ecology

Article

The relationship between animal cognition and consistent among-individual behavioral differences (i.e., behavioral types, animal personality, or coping styles), has recently received increased research attention. Focus has mainly been on linking different behavioral types to performance in learning tasks. It has been suggested that behavioral differences could influence also how individuals use previously learnt information to generalize about new stimuli with similar properties. Nonetheless, this has rarely been empirically tested. Here, we therefore explore the possibility that individual variation in generalization is related to variation in behavioral types in red junglefowl chicks (Gallus gallus). We show that more behaviorally flexible chicks have a stronger preference for a novel stimulus that is intermediate between 2 learnt positive stimuli compared to more inflexible chicks. Thus, more flexible and inflexible chicks differ in how they generalize. Further, behavioral flexibility correlates with fearfulness, suggesting a coping style, supporting that variation in generalization is related to variation in behavioral types. How individuals generalize affects decision making and responses to novel situations or objects, and can thus have a broad influence on the life of an individual. Our results add to the growing body of evidence linking cognition to consistent behavioral differences.

The relationship between learning speed and personalityis age- and task-dependent in red junglefowl

2018. Josefina Zidar (et al.). Behavioral Ecology and Sociobiology 72

Article

Cognition is fundamental to animals’ lives and an important source of phenotypic variation. Nevertheless, research on individual variation in animal cognition is still limited. Further, although individual cognitive abilities have been suggested to be linked to personality (i.e., consistent behavioral differences among individuals), few studies have linked performance across multiple cognitive tasks to personality traits. Thus, the interplays between cognition and personality are still unclear. We therefore investigated the relationships between an important aspect of cognition, learning, and personality, by exposing young and adult red junglefowl (Gallus gallus) to multiple learning tasks (discriminative, reversal, and spatial learning) and personality assays (novel arena, novel object, and tonic immobility). Learning speed was not correlated across learning tasks, and learning speed in discrimination and spatial learning tasks did not co-vary with personality. However, learning speed in reversal tasks was associated with individual variation in exploration, and in an age-dependent manner. More explorative chicks learned the reversal task faster than less explorative ones, while the opposite association was found for adult females (learning speed could not be assayed in adult males). In the same reversal tasks, we also observed a sex difference in learning speed of chicks, with females learning faster than males. Our results suggest that the relationship between cognition and personality is complex, as shown by its task- and age-dependence, and encourage further investigation of the causality and dynamics of this relationship.

Biased generalization of salient traits drives the evolution of warning signals

2018. Gabriella Gamberale-Stille (et al.). Proceedings of the Royal Society of London. Biological Sciences 285 (1877)

Article

The importance of receiver biases in shaping the evolution of many signalling systems is widely acknowledged. Here, we show that receiver bias can explain which traits evolve to become warning signals. For warning coloration, a generalization bias for a signalling trait can result from predators learning to discriminate unprofitable from profitable prey. However, because the colour patterns of prey are complex traits with multiple components, it is crucial to understand which of the many aspects of prey appearance evolve into signals. We provide experimental evidence that the more salient differences in prey traits give rise to greater generalization bias, corresponding to stronger selection towards trait exaggeration. Our results are based on experiments with domestic chickens as predators in a Skinner-box-like setting, and imply that the difference in appearance between profitable and unprofitable prey that is most rapidly learnt produces the greatest generalization bias. As a consequence, certain salient traits of unprofitable prey are selected towards exaggeration to even higher salience, driving the evolution of warning coloration. This general idea may also help to explain the evolution of many other striking signalling traits found in nature.

A comparison of animal personality and coping styles in the redjunglefowl

2017. Josefina Zidar (et al.). Animal Behaviour 130, 209-220

Article

There is an increased focus in biology on consistent behavioural variation. Several terms are used to describe this variation, including animal personality and coping style. Both terms describe between-individual consistency in behavioural variation; however, they differ in the behavioural assays typically used, the expected distribution of response variables, and whether they incorporate variation in behavioural flexibility. Despite these differences, the terms are often used interchangeably. We conducted experiments using juvenile and adult red junglefowl, Gallus gallus, as subjects to explore the degree to which animal personality and coping styles overlap. We demonstrate that animal personality and coping styles can be described in this species, and that shyer individuals had more flexible responses, as expected for coping styles. Behavioural responses from both personality and coping style assays had continuous distributions, and were not clearly separated into two types. Behavioural traits were not correlated and, hence, there was no evidence of a behavioural syndrome. Further, behavioural responses obtained in personality assays did not correlate with those from coping style tests. Animal personality and coping styles are therefore not synonymous in the red junglefowl. We suggest that the terms animal personality and coping style are not equivalent and should not be used interchangeably.

Aniara - en revy om människan i tid och rum

2016. Alexandra Balogh, Johanna Ethnersson Pontara, Jacob Derkert.

The opera Aniara by Karl-Birger Blomdahl premiered in 1959 and gained much attention forcombining its general serial style with other musical stylistic elements, as it alludes to and citesworks of other styles such as romanticism and jazz. This circumstance was considered amongother things to have led to Aniaras success, as it made the modernistic music more accessible to ageneral audience. I analyse two scenes in Aniara which contain allusions to and citations ofEllington's Ko-ko, Alfvén's Midsommarvaka, Shostakovich's Fifth Symphony, Beethoven's Ninthand the Swedish psalm Tryggare kan ingen vara regarding their intertextual meanings andaccording to Claudia Gorbman's theory of narrativity in film music. The overall function of theallusions and citations is to describe the conflicting emotions and mental states of the people ofthe spaceship Aniara: how they react to the occurring events during their voyage in space andtheir lack of hope. The intertextual references deepen the understanding of the narrative, and thesections with allusions are perhaps comparable to the aria in 1800th century opera, while themainly modernistic passages have a function similar to the drama-propelling recitative. Stylisticdiversity was not new in 20th century opera at the time of Aniara's premiere, however, the clearintertextuality of Blomdahl's allusions in service of narrative can be seen as ahead of its time.

FEATURE SALTATION AND THE EVOLUTION OF MIMICRY

2012. Gabriella Gamberale-Stille (et al.). Evolution 66 (3), 807-817

Article

In Batesian mimicry, a harmless prey species imitates the warning coloration of an unpalatable model species. A traditional suggestion is that mimicry evolves in a two-step process, in which a large mutation first achieves approximate similarity to the model, after which smaller changes improve the likeness. However, it is not known which aspects of predator psychology cause the initial mutant to be perceived by predators as being similar to the model, leaving open the question of how the crucial first step of mimicry evolution occurs. Using theoretical evolutionary simulations and reconstruction of examples of mimicry evolution, we show that the evolution of Batesian mimicry can be initiated by a mutation that causes prey to acquire a trait that is used by predators as a feature to categorize potential prey as unsuitable. The theory that species gain entry to mimicry through feature saltation allows us to formulate scenarios of the sequence of events during mimicry evolution and to reconstruct an initial mimetic appearance for important examples of Batesian mimicry. Because feature-based categorization by predators entails a qualitative distinction between nonmimics and passable mimics, the theory can explain the occurrence of imperfect mimicry.

Feature theory and the two-step hypothesis of Müllerian mimicry evolution

2010. Alexandra C.V. Balogh (et al.). Evolution 64 (3), 810-822

Article

The two-step hypothesis of Müllerian mimicry evolution states that mimicry starts with a major mutational leap between adaptive peaks, followed by gradual fine-tuning. The hypothesis was suggested to solve the problem of apostatic selection producing a valley between adaptive peaks, and appears reasonable for a one-dimensional phenotype. Extending the hypothesis to the realistic scenario of multidimensional phenotypes controlled by multiple genetic loci can be problematic, because it is unlikely that major mutational leaps occur simultaneously in several traits. Here we consider the implications of predator psychology on the evolutionary process. According to feature theory, single prey traits may be used by predators as features to classify prey into discrete categories. A mutational leap in such a trait could initiate mimicry evolution. We conducted individual-based evolutionary simulations in which virtual predators both categorize prey according to features and generalize over total appearances. We found that an initial mutational leap towards feature similarity in one dimension facilitates mimicry evolution of multidimensional traits. We suggest that feature-based predator categorization together with predator generalization over total appearances solves the problem of applying the two-step hypothesis to complex phenotypes, and provides a basis for a theory of the evolution of mimicry rings.

Predator psychology and mimicry evolution - a theoretical analysis

2009. Alexandra Balogh, Olof Leimar, Michael Speed.

Thesis (Doc)

The evolution of Müllerian mimicry depends on many factors, among which predator psychology is the most important one. Predator avoidance learning, generalization and discrimination are primary selective agents during the evolutionary process. This thesis investigates an issue that has been a matter of debate since the 19th century; the question of how a mutant of a potential mimic population can escape the apostatic selection caused by predators that neither recognize it as a member of its own population, nor as being similar to its future model. In paper I, we investigate one of the ideas concerning this issue. Fisher stated that mimicry can evolve gradually by the displacement of an adaptive peak in a fitness landscape. We find this to be a plausible scenario, under certain conditions regarding predator generalization. In paper II, we further investigate the gradual evolutionary process and the implications of different generalization gradients. We find that the gradual process might be even more general than has previously been assumed and that abundant genetic variation in prey populations is an important factor in combination with predator generalization. In paper III, we examine another suggested solution to the problem of apostatic selection, the so-called two-step process, which can be problematic to extend to multiple prey traits. We find that the two-step process works for multidimensional traits provided that predators use feature-based generalization. The selective landscape of mimicry evolution is also shaped by the cost-benefit relationships for models and mimics. In paper IV we explore this matter, by applying the Rescorla-Wagner theory of learning to mimicry. We find that if variation in prey unpalatability gives rise to surprise, the learning rate is increased. This leads to unexpected kinds of mimicry that are more mutualistic than Müllerian mimicry has previously been assumed to be.

Consummatory simultaneous positive and negative contrast in fallow deer: implications for selectivity

2009. Ulrika Alm Bergvall, Alexandra C.V. Balogh. Mammalian Biology 74 (3), 236-239

Article

Predator psychology and the evolution of Müllerian mimicry

2008. Alexandra Balogh.

Thesis (Lic)

Learning and the mimicry spectrum: from quasi-Bates to super-Müller

2008. Alexandra C.V. Balogh, Gabriella Gamberale-Stille, Olof Leimar. Animal Behaviour 76 (5), 1591-1599

Article

Müllerian mimicry is the mutualistic resemblance between two defended species, while Batesian mimicry is the parasitic resemblance between a palatable species (the mimic) and an unpalatable one (the model). These two kinds of mimicry are traditionally seen as extreme ends of a mimicry spectrum. For the range in between, it has been suggested that mimetic relations between unequally defended species could be parasitic, and this phenomenon has been referred to as quasi-Batesian mimicry. Where a mimetic relation is placed along the mimicry spectrum depends on the assumptions made about predator learning. In this work, we use a variant of the Rescorla-Wagner learning model for virtual predators to analyse the different possible components of the mimicry spectrum. Our model entails that the rate of associative learning is influenced by variation in the stimuli to be learned. Variable stimuli, i.e. unequal defences, can increase the predator learning rate and thus lead to an increased level of mutualism in a mimetic relation. In our analysis, we make use of the concepts of super-Müllerian mimicry, where the benefit of mimicry is even greater than in traditional Müllerian mimicry, and quasi-Müllerian mimicry, where mimicry by a palatable mimic is mutualistic. We suggest that these types of mimicry should be included in the mimicry spectrum along with Müllerian, Batesian and quasi-Batesian mimicry.

Evolutionary implications of the form of predator generalisation for aposematic signals and mimicry in prey

2008. Graeme D. Ruxton (et al.). Evolution: International Journal of Organic Evolution 62 (11), 2913-2921

Article

Generalization is at the heart of many aspects of behavioral ecology; for foragers it can be seen as an essential feature of learning about potential prey, because natural populations of prey are unlikely to be perfectly homogenous. Aposematic signals are considered to aid predators in learning to avoid a class of defended prey. Predators do this by generalizing between the appearance of prey they have previously sampled and the appearance of prey they subsequently encounter. Mimicry arises when such generalization occurs between individuals of different species. Our aim here is to explore whether the specific shape of the generalization curve can be expected to be important for theoretical predictions relating to the evolution of aposematism and mimicry. We do this by a reanalysis and development of the models provided in two recent papers. We argue that the shape of the generalization curve, in combination with the nature of genetic and phenotypic variation in prey traits, can have evolutionary significance under certain delineated circumstances. We also demonstrate that the process of gradual evolution of Müllerian mimicry proposed by Fisher is particularly efficient in populations with a rich supply of standing genetic variation in mimetic traits.

Müllerian mimicry: an examination of Fisher's theory of gradual evolutionary change

2005. Alexandra C.V. Balogh, Olof Leimar. Proceedings of the Royal Society of London. Biological Sciences 272, 2269-2275

Article

In 1927, Fisher suggested that Müllerian mimicry evolution could be gradual and driven by predator generalization. A competing possibility is the so-called two-step hypothesis, entailing that Müllerian mimicry evolves through major mutational leaps of a less-protected species towards a better-protected, which sets the stage for coevolutionary fine-tuning of mimicry. At present, this hypothesis seems to be more widely accepted than Fisher’s suggestion. We conducted individual-based simulations of communities with predators and two prey types to assess the possibility of Fisher’s process leading to a common prey appearance. We found that Fisher’s process worked for initially relatively similar appearances. Moreover, by introducing a predator spectrum consisting of several predator types with different ranges of generalization, we found that gradual evolution towards mimicry occurred also for large initial differences in prey appearance. We suggest that Fisher’s process together with a predator spectrum is a realistic alternative to the two-step hypothesis and, furthermore, that it has fewer problems with purifying selection. We also examined factors influencing gradual evolution towards mimicry and found that not only the relative benefits from mimicry but also the mutational schemes of the prey types matter.

Alexandra BaloghStudy Counsellor

Publications

Generalization of learned preferences covaries with behavioral flexibility in red junglefowl chicks

The relationship between learning speed and personalityis age- and task-dependent in red junglefowl

Biased generalization of salient traits drives the evolution of warning signals

A comparison of animal personality and coping styles in the redjunglefowl

Aniara - en revy om människan i tid och rum

FEATURE SALTATION AND THE EVOLUTION OF MIMICRY

Feature theory and the two-step hypothesis of Müllerian mimicry evolution

Predator psychology and mimicry evolution - a theoretical analysis

Consummatory simultaneous positive and negative contrast in fallow deer: implications for selectivity

Predator psychology and the evolution of Müllerian mimicry

Learning and the mimicry spectrum: from quasi-Bates to super-Müller

Evolutionary implications of the form of predator generalisation for aposematic signals and mimicry in prey

Müllerian mimicry: an examination of Fisher's theory of gradual evolutionary change