Across the animal kingdom, predation is a ubiquitous and omnipresent selective agent for a variety of traits. I aimed to address gaps in our knowledge pertaining to how predation shapes animal behavior. Many species of fish naturally occur in drainages that differ in the density of predators and exhibit obvious population divergence, making them ideal study organisms to investigate predator-driven behavioral evolution. In Chapter 1, I conducted a systematic review of the literature. The purpose of this review was to determine if predation acted as a stronger or weaker selective agent on particular behavioral traits (e.g., foraging, mating, antipredator etc.) across fish. This review showed that predation does not always drive behavior in predictable ways, and that some behavioral traits more consistently diverge than others. It was evident that antipredator behaviors are extremely variable but were typically measured in response to a visual stimulus. Investigations on intraspecific variation pertaining to how fish acquire, process, and respond to information across other sensory modalities are needed. To address this, I focused on a Neotropical fish, Brachyrhaphis rhabdophora (Poeciliidae), from Costa Rica that occur in distinct predation environments. For Chapter 2, I evaluated whether males and females exhibit differential responses to conspecific chemical alarm cues. Chemical alarm cues are released when a prey is injured by a predator and are an honest indicator of risk. It was clear that B. rhabdophora responded to alarm cues, but that males and females sometimes employed different antipredator strategies depending on what predation environment they were from. However, we know that in group-living species, such as B. rhabdophora, risk information can also be acquired indirectly through social cues. There are tradeoffs associated with relying on direct vs. indirect information, and these sources of information may sometimes conflict. For Chapter 3 I considered how B. rhabdophora integrates conflicting information to elicit antipredator behavior. I again exposed fish directly to chemical alarm cues and measured how their antipredator responses changed when visually observing conflicting or reinforcing social information. I found that individuals integrated personal and social information differently based on their evolutionary history with predators. Further, we found evidence that even a single observer fish is able to influence group behavior. Finally, for Chapter 4, I evaluated sex-specific variation in brain size across predation environments. According to the "expensive-tissue hypothesis" there should only be investment in brain tissue when there is sufficient selection for enhanced cognitive abilities. Prey under elevated selection from predators should invest more in cognitive traits to enhance survival, but how sex interplays with this effect is unclear. I found that females had higher relative total brain volumes than males, but males exhibited more variation across predation environments in the relative volumes for certain brain regions. This work as a whole suggests that, yes, evolutionary history matters for a variety of sensory-related traits in B. rhabdophora.

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<p> </p> <p>The degree of self-fertilization in a population determines levels of genetic variation and high selfing rates could thus limit future adaptive potential. Theory predicts that intermediate selfing rates should not persist, yet many plants exhibit mixed mating. Cleistogamy is a floral heteromorphism where individuals produce both showy potentially outcrossing chasmogamous flowers and closed obligately selfing cleistogamous flowers. Reproduction via cleistogamous flowers is thought to be beneficial because of their greater energetic economy compared to chasmogamous flowers but can be costly if selfing leads to inbreeding depression or accelerates the fixation of deleterious mutations within populations. Cleistogamy has evolved independently multiple times and can be used to study the maintenance of adaptive mixed mating. To investigate this, I estimated the costs and benefits of selfing in three populations of <em>Ruellia humilis </em>Nutt (Acanthaceae) in greenhouse common garden experiments. To quantify the costs, I performed hand pollinations and quantified fitness components of progeny resulting from selfing and outcrossing within- and between-populations. To quantify the relative energetic advantage of cleistogamous flowers, I measured dry flower mass, fertility, seed number per fruit, and pollen-ovule ratios of both types of flowers. I found negative cumulative inbreeding depression in all populations, indicative of selfed progeny outperforming outcrossed progeny. While the fitness consequences of between population outcrossing ranged from heterosis to outbreeding depression. When looking at the energetic benefits of selfing, I found that the cost of reproduction via cleistogamous flowers was between 3 and 14-fold less than the cost for outcrossing flowers. Finally, I combined data on inbreeding depression and the energetic costs of reproduction and found that chasmogamous flowers of <em>R. humilis </em>must provide between a 3 to a 45-fold fitness advantage to be maintained, the magnitude of which was dependent upon maternal population. Overall, I conclude that none of the existing hypotheses are sufficient enough to provide the selective advantage needed to explain the persistence of chasmogamous flowers in <em>R. humilis</em>. Without any supported explanations for the maintenance of mixed mating, the exploration of genetic constraints on the loss of chasmogamous flowers could solve this long-standing mystery. </p>

O objetivo geral desta dissertação é testar hipóteses relacionadas à duração das linhagens (i.e. o intervalo de tempo definido pela origem e extinção das diferentes linhagens) e à dinâmica da diversificação dos ruminantes. Para isso, nós usamos compilações públicas de dados fósseis e modelos probabilísticos. Como a literatura macroevolutiva se aproveita das múltiplas escalas taxonômicas onde é possível estudar a mudança da biodiversidade no tempo, os dois capítulos desta dissertação testam suas hipóteses no níveis de espécie e gênero na tentativa de iluminar o papel da escala na manifestação dos padrões macroevolutivos. No primeiro capítulo, nós investigamos se tratamentos taxonômicos distintos aplicados aos dados brutos alteram os resultados obtidos por um método macroevolutivo. Nossos resultados sugerem que os dados, mesmo após passar por diferentes tratamentos, indicam similares dinâmicas de diversificação tanto no nível taxonômico dos gêneros quanto no nível das espécies. Por outro lado, as comparações entre dois conjuntos de dados inicialmente distintos podem gerar diferenças consideráveis na dinâmica da diversificação e inclusive indicar diferenças entre escalas taxonômicas. Esses resultados são robustos mesmo que as imperfeições do registro fóssil sejam consideradas de diferentes maneiras pelo método usado. No segundo capítulo, nós usamos modelos probabilísticos para testar uma importante hipótese macroevolutiva que é também considerada uma premissa para vários estudos da área: a de que a probabilidade de extinção de qualquer linhagem é independente da sua longevidade, ou seja, do intervalo de tempo que a linhagem já viveu. Nossos resultados sugerem um padrão consistente de diminuição na probabilidade de extinção conforme as espécies vivem por mais tempo, enquanto que o padrão observado do no nível dos gêneros é menos claro. Este resultado não só enriquece o nosso conhecimento a respeito da dinâmica da extinção de linhagens, como sugere que a premissa de independência de idade na probabilidade de extinção (importante para vários estudos macroevolutivos) pode não ser válida, pelo menos para Ruminantia. Nós esperamos que os dados e ideias aqui expostos interajam com novas ideias e dados do leitor, estimulando o desenvolvimento da macroevolução / The main goal of this dissertation is to test hypotheses related to the duration of the lineages (i.e. the time interval between the origin and extinction of each lineage) and to the diversification dynamics of the ruminants. To achieve this goal, we used public compilations of fossil data and probabilistic models. As the macroevolutionary literature take advantage of multiple taxonomic scales in which is possible to study biodiversity changes through time, the two chapters of this dissertation tested different hypotheses in both the species and genus levels, as na attempt to shed some light on the role of scale influencing the macroevolutionary phenomena. In the first chapter, we investigated if different taxonomic treatments applied over the raw data significantly change the results obtained from a macroevolutionary method. Our results suggest that the same data, even passing through different data curations, indicate similar diversification dynamics in species and genus taxonomic levels. On the other hand, data that comes from different sources may present considerable differences in the diversification dynamics, and even indicate differences between taxonomic scales. These results are robust to different considerations of the preservation biases of the fossil record by the method. In the second chapter, we used probabilistic models to test an importante macroevolutionary hypothesis that is also considered a premise of several macroevolutionary studies: that the probability of extinction of any lineage is independent of its longevity (the time span determined by the origination and extinction of each lineage). Our results suggest a consistent pattern of decreasing extinction probability as species live for longs periods of time, but the pattern presented by the genera is less clear. These results not only enhance our knowledge about extinction dynamics, but it also suggests that the premise of age independence in the extinction probability (important for several macroevolutionary studies) might not be valid, at least for Ruminatia. We hope our data and ideas interact with new ideas and data from the reader to stimulate the development of the macroevolutionary field

Optimal Foraging Theory (OFT) has its origin in processualistic ideas in 1960s with traces back to the dawn of the archaeological science in the 19th century. The OFT model is based on the construction of an individual’s food item selection understood as an evolutionary construct that maximizes the net energy gained per unit feeding time. The most common variants are diet patch choice, diet breadth/prey choice models and Marginal Value Theorem (MVT). The theory introduced experimental studies combined with mathematically data analyses and computer simulations. The results visualized in the experimental diagrammed curve are possible to compare with the archaeological records. What is “optimal” is an empirical question not possible to know but still useful as a benchmark for measuring culture. The theory is common in USA but still not in Europe. OFT seems to be useful in hunter-gatherer research looking at human decisions, energy flow, depression of resources and extinction. This literature review concludes that the prey-choice/diet-breadth model seems to be useful for hunter-gatherer research on Gotland focusing on possible causes of the hiatus in archaeological records between 5000-4500 BC. / Optimal Foraging Theory (OFT) har sitt ursprung i de processualistiska ideérna under 1960-talet med spår tillbaka till arkeologins början som vetenskap under 1800-talet. OFT modellen baseras på konstruktionen av en individs födoämnesval som förstås som en evolutionär konstruktion som maximerar nettoenergiintaget per tidsenhet som gått åt för försörjningen. De vanligaste varianterna är patch-choice, diet breadth/prey choice modellerna och Marginal Value Theorem (MVT). Experimentella studier genomförs och data bearbetas matematiskt och visar datorsimulerade kurvdiagram möjliga att jämföra med arkeologiska källmaterial. Vad som är ”optimalt” är en empirisk fråga omöjlig att veta men användbar ändå som en slag referens för att mäta kultur. Teorin är vanlig i USA men ännu inte i Europa. OFT förefaller användbar inom forskning av jägare-samlare om man fokuserar på beslutsfattande, energiflöde, depression av resurser och utrotning av arter. Slutsatsen i denna litteraturöversikt är att prey choice/diet breadth modellen tycks vara användbar för gotländsk jägare-samlare-forskning som fokuserar på möjliga orsaker till de arkeologiska fyndens hiatus mellan 5000-4500 BC.

A fundamental goal in ecology and evolutionary biology has been to understand how microevolutionary forces affect the origin and maintenance of mutualisms over ecological and evolutionary time scales. Mutualistic partners vary in the reciprocal benefits they provide, yet the role of partner variation on microevolutionary forces that impact the maintenance of mutualisms is unclear. Using the mutualism between legumes and nitrogen fixing symbionts, my dissertation investigated the ecological and evolutionary consequences of variation in partner quality. In the first experiment, I demonstrate how insect herbivory can change the costs and benefits of associating with exploiters, and that some degree of exploitation from non-beneficial rhizobia can reduce insect herbivory, thus removing the fitness advantage of associating purely with beneficial rhizobia. In the second study, I examine how rhizobia genotype modifies competition between hosts grown in kin and non-kin groups. I show that lower fitness in plant kin groups can simply be a by-product of genetic variance in plant size and non-linear relationships between plant size and fitness. I further show that the symbiotic community can change difference in fitness between kin and non-kin groups independent of these by-product effects. In my last chapter, I provide the first empirical evidence that an important mechanism for mutualism stability-- the ability for hosts to preferentially associate with beneficial rhizobia-- is genetically variable and can evolve in response to exploitation. I also show that host preference for beneficial rhizobia can be maintained in legume populations, even in the absence of exploitation. My dissertation provides insight into the potential evolutionary dynamics of stabilizing mechanisms by suggesting that the agents of selection that affect the level of host exploitation can come from biotic factors other than the exploiters themselves. My dissertation has also shown that inclusion of other ecological interactions, such as herbivory, can provide valuable perspective on fitness effects of symbionts on their hosts, and can even change our fundamental assumptions about the effects of exploitation on host fitness, which has formed the backbone of mutualism theory.

A fundamental goal in ecology and evolutionary biology has been to understand how microevolutionary forces affect the origin and maintenance of mutualisms over ecological and evolutionary time scales. Mutualistic partners vary in the reciprocal benefits they provide, yet the role of partner variation on microevolutionary forces that impact the maintenance of mutualisms is unclear. Using the mutualism between legumes and nitrogen fixing symbionts, my dissertation investigated the ecological and evolutionary consequences of variation in partner quality. In the first experiment, I demonstrate how insect herbivory can change the costs and benefits of associating with exploiters, and that some degree of exploitation from non-beneficial rhizobia can reduce insect herbivory, thus removing the fitness advantage of associating purely with beneficial rhizobia. In the second study, I examine how rhizobia genotype modifies competition between hosts grown in kin and non-kin groups. I show that lower fitness in plant kin groups can simply be a by-product of genetic variance in plant size and non-linear relationships between plant size and fitness. I further show that the symbiotic community can change difference in fitness between kin and non-kin groups independent of these by-product effects. In my last chapter, I provide the first empirical evidence that an important mechanism for mutualism stability-- the ability for hosts to preferentially associate with beneficial rhizobia-- is genetically variable and can evolve in response to exploitation. I also show that host preference for beneficial rhizobia can be maintained in legume populations, even in the absence of exploitation. My dissertation provides insight into the potential evolutionary dynamics of stabilizing mechanisms by suggesting that the agents of selection that affect the level of host exploitation can come from biotic factors other than the exploiters themselves. My dissertation has also shown that inclusion of other ecological interactions, such as herbivory, can provide valuable perspective on fitness effects of symbionts on their hosts, and can even change our fundamental assumptions about the effects of exploitation on host fitness, which has formed the backbone of mutualism theory.

abstract: How fast is evolution? In this dissertation I document a profound change that occurred around the middle of the 20th century in the way that ecologists conceptualized the temporal and spatial scales of adaptive evolution, through the lens of British plant ecologist Anthony David Bradshaw (1926–2008). In the early 1960s, one prominent ecologist distinguished what he called “ecological time”—around ten generations—from “evolutionary time”— around half of a million years. For most ecologists working in the first half of the 20th century, evolution by natural selection was indeed a slow and plodding process, tangible in its products but not in its processes, and inconsequential for explaining most ecological phenomena. During the 1960s, however, many ecologists began to see evolution as potentially rapid and observable. Natural selection moved from the distant past—a remote explanans for both extant biological diversity and paleontological phenomena—to a measurable, quantifiable mechanism molding populations in real time. The idea that adaptive evolution could be rapid and highly localized was a significant enabling condition for the emergence of ecological genetics in the second half of the 20th century. Most of what historians know about that conceptual shift and the rise of ecological genetics centers on the work of Oxford zoologist E. B. Ford and his students on polymorphism in Lepidotera, especially industrial melanism in Biston betularia. I argue that ecological genetics in Britain was not the brainchild of an infamous patriarch (Ford), but rather the outgrowth of a long tradition of pastureland research at plant breeding stations in Scotland and Wales, part of a discipline known as “genecology” or “experimental taxonomy.” Bradshaw’s investigative activities between 1948 and 1968 were an outgrowth of the specific brand of plant genecology practiced at the Welsh and Scottish Plant Breeding stations. Bradshaw generated evidence that plant populations with negligible reproductive isolation—separated by just a few meters—could diverge and adapt to contrasting environmental conditions in just a few generations. In Bradshaw’s research one can observe the crystallization of a new concept of rapid adaptive evolution, and the methodological and conceptual transformation of genecology into ecological genetics. / Dissertation/Thesis / Doctoral Dissertation Biology 2015

The topic of the presented thesis is evolution of the arvicoline rodents (Cricetidae) using the phylogenetic approach. Phylogenetic relationships within the Arvicolinae were examined based on two genes (mitochondrial cytb, nuclear GHR exon 10) and approx. 470 morphological, developmental, behavioural, ecological and cytogenetic characters. The thesis consists of four related topics: (i) Phylogeny of arvicoline rodents (Robovský et al. 2008: Zool. Scr. 37: 571-590); (ii) Fossils, phylogeny and morphological evolution in the Arvicolinae (Rodentia: Cricetidae); (iii) Enamel, diet and habitat evolution in arvicoline rodents (Cricetidae); and (iv) Vole population cycles: evolutionary history or actual life histories?.