% pubman genre = thesis
@phdthesis{item_3617282,
title = {{From antelopes to zebras: which factors explain inter- and intraspecific variation in ungulate cognition?}},
author = {Schaffer, Alina},
language = {eng},
year = {2024},
abstract = {{Cognition is the mechanism by which animals acquire, process, store, and act on information from the environment, including perception, learning, memory, and decision-making (Shettleworth 2009a). Comparative cognition aims to investigate how cognitive skills are distributed across taxa, and thus find the socio-ecological challenges that might explain this distribution (Healy et al. 2009; MacLean et al. 2012). As a result, comparative cognition allows researchers to find variations in problem-solving abilities, better understand the processes that lead to the emergence of complex cognition, and understand the evolutionary challenges that are linked to the emergence of specific skills (Barrett et al. 2002; Bueno-Guerra and Amici 2018; Dunbar 1992; Harcourt et al. 1988; MacLean et al. 2012; Shettleworth 2009a). In their natural environment, animals face a variety of ecological and social challenges. Theories of cognitive evolution suggest that these challenges have favoured the emergence of cognitive skills that allow individuals to better cope with the requirements they encounter in their ecological niches, like foraging or interacting with conspecifics (Ashton et al. 2018; Holekamp 2007; Tomasello and Call 1997). Therefore, cognitive skills usually evolve when individuals face specific problems, either in a physical context (i.e., cognitive processes used to solve physical problems) or in a social context (i.e., cognitive processes used to interact with social partners). In my thesis, I focus on physical cognition and object understanding, which includes how animals deal with inanimate objects and what they understand about their spatial, temporal, and causal relations. One reason why some species may have evolved different cognitive abilities is that they face specific ecological challenges which the evolution of complex cognition, and thus greater behavioural flexibility, allows to overcome more efficiently. These ecological challenges include, for example, dietary breadth or domestication. Moreover, social challenges may also constitute a strong selection pressure for the evolution of enhanced cognitive abilities. When social life is complex, individuals must use flexible cognitive strategies to recognize other individuals, keep track of their relationships, and predict, coordinate and manipulate their behaviours. Unlike objects, social partners are reactive, unpredictable and respond with different behaviours to one{\textquotesingle}s actions; therefore, social complexity would present high cognitive challenges and strong selection pressures for the evolution of cognition. Social challenges include, for example, living in large groups, frequently engaging in social interactions, or showing fission-fusion dynamics. Apart from interspecific variation, cognition also varies across conspecific individuals, depending on factors such as sex, age, rank, social integration or early life experiences. In addition to these characteristics, personality traits (i.e., interindividual behavioural differences that are consistent over time and across contexts) may also influence performance on cognitive tasks. In this project, I used ungulates as a model to directly test socio-ecological hypotheses about the evolution of cognition. Ungulates are an ideal model to test cognitive abilities from a comparative perspective. First, they show an impressive diversity of socio-ecological traits, which allows for a reliable contrast of different evolutionary hypotheses. Second, there are very few studies that have examined the relationship between cognition and socio-ecological traits in ungulates, and the largest majority have used neuroanatomical proxies for cognitive skills. Third, although ungulates are economically important for humans, we still know little about their cognition, and about the cognitive enrichments that might be used to improve their welfare. This thesis aimed to test variation in different cognitive skills across several ungulate species, to assess the ecological, social and individual factors that best explain inter- and intra-specific variation in their cognitive abilities. I used well-established experimental procedures to test individuals{\textasciiacute} object permanence, short-term memory, causality, understanding of object properties, gravity and quantity discrimination skills. Further, I tested individuals{\textasciiacute} neophobic reactions to new objects. All tests were carried out on captive individuals in the zoos of Leipzig (Germany) and Barcelona (Spain), and partially in other European zoos. I tested the following species in one or more studies: goats (Capra aegagrus hircus), llamas (Lama glama), guanacos (Lama guanicoe), Grevy{\textquoteright}s zebras (Equus grevyi), Chapman{\textquoteright}s zebras (Equus burchelli chapmanni), rhinos (Diceros bicornis michaeli), giraffes (Giraffa camelopardalis rothschildi), European bisons (Bison bonasus), Forest buffalos (Syncerus caffer nanus), oryx (Oryx dammah), dromedaries (Camelus dromedarius), red deer (Cervus elaphus), barbary sheep (Ammotragus lervia), Przewalski horses (Equus ferus przewalskii), and sheep (Ovis aries). In summary, 15 different ungulate species were tested in well-established experimental procedures to test individuals{\textasciiacute} object permanence, short-term memory, causality, understanding of object properties, gravity and quantity discrimination skills. Further, individuals{\textasciiacute} neophobic reactions to new objects were tested. In the first paper on neophobia, I tested neophobic responses to novel objects in different ungulate species and found differences both within and across species. In particular, more socially integrated individuals were more neophobic than less central ones, showing a higher latency to approach food that was closer to a novel object. Further, Barbary sheep were less neophobic than all the other species and spent a higher proportion of time close to novel objects. In the second paper, I tested whether higher levels of fission-fusion dynamics predict better cognitive skills. I found Grevy{\textasciiacute}s zebras (which are characterized by higher fission-fusion dynamics) to perform better than Chapman{\textasciiacute}s zebras in tasks requiring inference and quantity discrimination skills. In the third paper, I tested the cognitive skills of ungulates in different object-understanding tasks and showed that all species were able to understand that objects continue to exist even when they are out of sight, remember the location of objects after delays of up to 60 seconds (short-term memory), and infer the location of the food from the presence or lack of sound produced when shaking containers. I found that subjects, across species, had some understanding of object properties and gravity, being able to locate food behind one of the two occluders based on their shape and inclination, and searching for falling food in the correct location. In the fourth paper, individuals performed above chance levels in most conditions of the Numerosity and Size tasks, in which they had to rely on item number and size to maximize food intake. Overall, I detected inter- and intra-specific variation across the cognitive tasks performed. The socio-ecological factors that explained the inter-specific variation were domestication (i.e., species that have been selected for living in close relationships with humans), group size (i.e., the actual size of the tested group) and fission-fusion dynamics (i.e., individuals living in groups frequently splitting into subgroups of varying size and composition). Apart from inter-specific variation, I could also detect inter-individual variation, with socially more integrated individuals being more neophobic. Taken together, the results of my thesis show that different inter- and intra-specific factors lead to variation in cognitive skills between ungulate species.}},
}