Daniel I Bolnick

Daniel I Bolnick
University of Texas at Austin | UT · Department of Integrative Biology

PhD

About

208
Publications
52,946
Reads
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20,784
Citations
Introduction
Additional affiliations
September 2009 - present
Howard Hughes Medical Institute
Position
  • Early Career Scientist
September 2004 - present
University of Texas at Austin
Position
  • Professor (Full)
September 1998 - August 2003
University of California, Davis
Position
  • PhD Student

Publications

Publications (208)
Article
Parasites impose fitness costs on their hosts. Biologists often assume that natural selection favors infection-resistant hosts. Yet, when the immune response itself is costly, theory suggests that selection may sometimes favor loss of resistance, which may result in alternative stable states where some populations are resistant and others are toler...
Preprint
Full-text available
Measuring gene expression simultaneously in both hosts and symbionts offers a powerful approach to explore the biology underlying species interactions. Such dual or simultaneous RNAseq approaches have primarily been used to gain insight into gene function in model systems, but there is opportunity to expand and apply these tools in new ways to unde...
Article
Full-text available
Sexual dimorphism is a ubiquitous source of within‐species variation, yet the community‐level consequences of sex differences remain poorly understood. Here, we analyze a bitrophic model of two competing resource species and a sexually‐reproducing consumer species. We show that consumer sex differences in resource acquisition can have striking cons...
Article
Full-text available
Closely related populations often differ in resistance to a given parasite, as measured by infection success or failure. Yet, the immunological mechanisms of these evolved differences are rarely specified. Does resistance evolve via changes to the host's ability to recognize that an infection exists, actuate an effective immune response, or attenua...
Article
Coevolution occurs when species interact to influence one another's fitness, resulting in reciprocal evolutionary change. In many coevolving lineages, trait expression in one species is modified by the genotypes and phenotypes of the other, forming feedback loops reminiscent of models of intraspecific social evolution. Here, we adapt the theory of...
Preprint
Full-text available
Pathogenic infection is an important driver of many ecological processes. Furthermore, variability in immune function is an important driver of differential infection outcomes. New evidence would suggest that immune variation extends to broad cellular structure of immune systems. However, variability at such broad levels is traditionally difficult...
Article
Full-text available
When predators consume prey, they risk becoming infected with their prey's parasites, which can then establish the predator as a secondary host. A predator population's diet therefore influences what parasites it is exposed to, as has been repeatedly shown in many species such as threespine stickleback (Gasterosteus aculeatus) (more benthic-feeding...
Article
Full-text available
Vertebrate immunity is a complex system consisting of a mix of constitutive and inducible defenses. Furthermore, host immunity is subject to selective pressure from a range of parasites and pathogens which can produce variation in these defenses across populations. As populations evolve immune responses to parasites, they may adapt via a combinatio...
Preprint
Parasites impose fitness costs on their hosts. Biologists therefore tend to assume that natural selection favors infection-resistant hosts. Yet, when the immune response itself is costly, theory suggests selection may instead favor loss of resistance. Immune costs are rarely documented in nature, and there are few examples of adaptive loss of resis...
Article
Fitness of aquatic animals can be limited by the scarcity of nutrients such as long-chain polyunsaturated fatty acids, especially docosahexaenoic acid (DHA). DHA availability from diet varies among aquatic habitats, imposing different selective pressures on resident animals to optimize DHA acquisition and synthesis. For example, DHA is generally po...
Article
Full-text available
Parasites can mediate host fitness both directly, via effects on survival and reproduction, or indirectly by inducing host immune defense with costly side‐effects. The evolution of immune defense is determined by a complex interplay of costs and benefits of parasite infection and immune response, all of which may differ for male and female hosts in...
Article
Full-text available
Commensal microbial communities have immense effects on their vertebrate hosts, contributing to a number of physiological functions, as well as host fitness. In particular, host immunity is strongly linked to microbiota composition through poorly understood bi-directional links. Gene expression may be a potential mediator of these links between mic...
Preprint
Full-text available
Coevolution occurs when species interact to influence one another's fitness, resulting in reciprocal evolutionary change. In many coevolving lineages, trait expression in one species is modified by the genotypes and phenotypes of the other, forming feedback loops reminiscent of models of intraspecific social evolution. Here, we adapt the theory of...
Article
Full-text available
Major Histocompatibility Complex (MHC) genes encode for proteins that recognize foreign protein antigens to initiate T‐cell mediated adaptive immune responses. They are often the most polymorphic genes in vertebrate genomes. How evolution maintains this diversity is still an unsettled issue. Three main hypotheses seek to explain the maintenance of...
Article
Full-text available
Recent methodological advances have led to a rapid expansion of evolutionary stud-ies employing three-dimensional landmark-based geometric morphometrics (GM). GM methods generally enable researchers to capture and compare complex shape phenotypes, and to quantify their relationship to environmental gradients. However, some recent studies have shown...
Article
The repeated occurrence of similar phenotypes in independent lineages (i.e., parallel evolution) in response to similar ecological conditions can provide compelling insights into the process of adaptive evolution. An intriguing question is to what extent repeated phenotypic changes are underlain by repeated changes at the genomic level and whether...
Article
Full-text available
A core goal of ecology is to understand the abiotic and biotic variables that regulate species distributions and community composition. A major obstacle is that the rules governing species distributions can change with spatial scale. Here, we illustrate this point using data from a spatially nested metacommunity of parasites infecting a metapopulat...
Preprint
Full-text available
Recent methodological advances have led to a rapid expansion of evolutionary studies employing three‐dimensional landmark‐based geometric morphometrics (GM). GM methods generally enable researchers to capture and compare complex shape phenotypes, and to quantify their relationship to environmental gradients. However, some recent studies have shown...
Preprint
Full-text available
Major Histocompatibility Complex (MHC) genes encode for proteins that recognize foreign protein antigens to initiate T-cell mediated adaptive immune responses. They are often the most polymorphic genes in vertebrate genomes. How evolution maintains this diversity is still an unsettled issue. Three main hypotheses seek to explain the maintenance of...
Preprint
Commensal microbial communities have immense effects on their vertebrate hosts, contributing to a number of physiological functions as well as host fitness. In particular, host immunity is strongly linked to microbiota composition through poorly understood bi-directional links. Gene expression may be a potential mediator of these links between micr...
Preprint
Despite the significant effect of host-parasite interactions on both ecological systems and organism health, there is still limited understanding of the mechanisms driving evolution of host resistance to parasites. One model of rapid evolution, the Baldwin Effect, describes the role of plasticity in adaptation to novel conditions, and subsequent ca...
Preprint
Full-text available
Parasites can mediate host fitness both directly, via effects on survival and reproduction, or indirectly by inducing host immune defense with costly side-effects. The evolution of immune defense is determined by a complex interplay of costs and benefits of parasite infection and immune response, all of which may differ for male and female hosts in...
Preprint
Full-text available
Closely related populations often differ in resistance to a given parasite, as measured by infection success or failure. Yet, the immunological mechanisms of these evolved differences are rarely specified. Does resistance evolve via changes to the host’s ability to recognize that an infection exists, actuate an effective immune response, or attenua...
Preprint
Full-text available
When predators consume prey, they risk becoming infected with their prey's parasites, which can then establish the predator as a secondary host. For example, stickleback in northern temperate lakes consume benthic or limnetic prey, which are intermediate hosts for distinct species of parasites (e.g. Eustrongylides nematodes in benthic oligocheates...
Article
Full-text available
Many metacommunities are distributed across habitat patches that are themselves aggregated into groups. Perhaps the clearest example of this nested metacommunity structure comes from multi-species parasite assemblages, which occupy individual hosts that are aggregated into host populations. At both spatial scales, we expect parasite community diver...
Article
Full-text available
Many generalist species consist of specialised individuals that use different resources. This within‐population niche variation can stabilise population and community dynamics. Consequently, ecologists wish to identify environmental settings that promote such variation. Theory predicts that environments with greater resource diversity favour ecolog...
Article
Since the New Synthesis, most migration‐selection balance theory predicted that there should be negligible differentiation over small spatial scales (relative to dispersal), because gene flow should erode any effect of divergent selection. Nevertheless, there are classic examples of microgeographic divergence, which theory suggests can arise under...
Article
Explanations of how organisms might adapt to urban environments have mostly focused on divergent natural selection and adaptive plasticity. However, differential habitat choice has been suggested as an alternative. Here, we test for habitat choice in enhancing crypsis in ground-perching grasshoppers colonizing an urbanized environment, composed of...
Article
Full-text available
The repeatability of adaptive radiation is expected to be scale-dependent, with determinism decreasing as greater spatial separation among "replicates" leads to their increased genetic and ecological independence. Threespine stickleback (Gasterosteus aculeatus) provide an opportunity to test whether this expectation holds for the early stages of ad...
Article
Full-text available
Evolutionary biologist tend to approach the study of the natural world within a framework of adaptation, inspired perhaps by the power of natural selection to produce fitness advantages that drive population persistence and biological diversity. In contrast, evolution has rarely been studied through the lens of adaptation’s complement, maladaptatio...
Article
Full-text available
The repeated evolution of similar phenotypes in independent populations (i.e. parallel or convergent evolution) provides an opportunity to identify genetic and ecological factors that influence the process of adaptation. Threespine stickleback fish ( Gasterosteus aculeatus ) are an excellent model for such studies, as they have repeatedly adapted t...
Preprint
Full-text available
Many metacommunities are distributed across habitat patches that are themselves aggregated into groups. Perhaps the clearest example of this nested metacommunity structure comes from multi-species parasite assemblages, which occupy individual hosts that are aggregated into host populations. At both spatial scales, we expect parasite community diver...
Preprint
Full-text available
Many generalist species consist of disparate specialized individuals, a phenomenon known as individual specialization. This within-population niche variation can stabilize population dynamics, reduce extinction risk, and alter community composition. But, we still only vaguely understand the ecological contexts that promote niche variation and its s...
Article
Evolutionary biologists have long trained their sights on adaptation, focusing on the power of natural selection to produce relative fitness advantages while often ignoring changes in absolute fitness. Ecologists generally have taken a different tack, focusing on changes in abundance and ranges that reflect absolute fitness while often ignoring rel...
Preprint
Full-text available
A core goal of ecology is to understand the abiotic and biotic variables that regulate species distributions and community composition. A major obstacle is that the rules governing species distribution can change with spatial scale. Here, we illustrate this point using data from a spatially nested metacommunity of parasites infecting a metapopulati...
Preprint
Full-text available
The repeatability of adaptive radiation is expected to be scale dependent, with determinism decreasing as greater spatial separation among ″replicates″ leads to their increased genetic and ecological independence. Threespine stickleback ( Gasterosteus aculeatus ) provide an opportunity to test whether this expectation holds for the early stages of...
Article
Parallel evolution across replicate populations has provided evolutionary biologists with iconic examples of adaptation. When multiple populations colonize seemingly similar habitats, they may evolve similar genes, traits, or functions. Yet, replicated evolution in nature or in the laboratory often yields inconsistent outcomes: Some replicate popul...
Article
Full-text available
Theoretical models of sexual selection suggest that male courtship signals can evolve through the build‐up of genetic correlations between the male signal and female preference. When preference is mediated via increased sensitivity of the signal characteristics, correlations between male signal and perception/sensitivity are expected. When signal e...
Article
Full-text available
The ecological multifunctionality of colour often results in multiple selective pressures operating on a single trait. Most research on colour evolution focuses on males because they are the most conspicuous sex in most species. This bias can limit inferences about the ecological drivers of colour evolution. For example, little is known about popul...
Data
Dataset of colour measurements, geographic information, time, and reproductive state. This is the total dataset, including field number, lake designation, raw RGB brightness levels, lake surface area in hectares, watershed designation, date (in month/day format), and gravidity designation, where 1 is gravid, and 0 is not gravid.
Preprint
Adaptive phenotypic divergence is typically studied across relatively broad spatial scales (continents, archipelagos, river basins) because at these scales we expect environmental differences to be strong, and the homogenizing effect of gene flow to be weak. However, phenotypic plasticity and phenotype-dependent habitat choice are additional mechan...
Article
Full-text available
Evolutionary ecologists aim to explain and predict evolutionary change under different selective regimes. Theory suggests that such evolutionary prediction should be more difficult for biomechanical systems in which different trait combinations generate the same functional output: "many-to-one mapping". Many-to-one mapping of phenotype to function...
Article
Full-text available
Heritable population differences in immune gene expression following infection can reveal mechanisms of host immune evolution. We compared gene expression in infected and uninfected threespine stickleback (Gasterosteus aculeatus) from two natural populations that differ in resistance to a native cestode parasite, Schistocephalus solidus. Genes in b...
Article
Full-text available
Melanomacrophage centers (MMCs) are aggregates of highly pigmented phagocytes found primarily in the head kidney and spleen, and occasionally the liver of many vertebrates. Preliminary histological analyses suggested that MMCs are structurally similar to the mammalian germinal center (GC), leading to the hypothesis that the MMC plays a role in the...
Article
Signal evolution is thought to depend on both a signal's detectability or conspicuousness (signal design) as well as any extractable information it may convey to a potential receiver (signal content). While theoretical and empirical work in sexual selection has largely focused on signal content, there has been a steady accrual of evidence that sign...
Article
Parasites can be a major cause of natural selection on hosts, which consequently evolve a variety of strategies to avoid, eliminate, or tolerate infection. When ecologically similar host populations present disparate infection loads, this natural variation can reveal immunological strategies underlying adaptation to infection and population diverge...
Article
Full-text available
The light environment influences an animal's ability to forage, evade predators, and find mates, and consequently is known to drive local adaptation of visual systems. However, the light environment may also vary over fine spatial scales at which genetic adaptation is difficult. For instance, in aquatic systems the available wavelengths of light ch...
Article
Two distinct forms of natural selection promote adaptive biological diversity. Divergent selection occurs when different environments favour different phenotypes, leading to increased differences between populations. Negative frequency-dependent selection occurs when rare variants within a population are favoured over common ones, increasing divers...
Article
Full-text available
Parallel evolution of similar traits by independent populations in similar environments is considered strong evidence for adaptation by natural selection. Often, however, replicate populations in similar environments do not all evolve in the same way, thus deviating from any single, predominant outcome of evolution. This variation might arise from...
Article
Major histocompatibility (MHC) genes encode proteins that play a central role in vertebrates' adaptive immunity to parasites. MHC loci are among the most polymorphic in vertebrates' genomes, inspiring many studies to identify evolutionary processes driving MHC polymorphism within populations, and divergence between populations. Leading hypotheses i...
Preprint
Full-text available
Selection against migrants is key to maintaining genetic differences between populations linked by dispersal. Yet, migrants are not just passively weeded out by selection. Migrants may mitigate fitness costs by proactively choosing among available habitats, or by phenotypic plasticity. We previously reported that a reciprocal transplant of lake and...
Article
Full-text available
The Clever Foraging Hypothesis asserts that organisms living in a more spatially complex environment will have a greater neurological capacity for cognitive processes related to spatial memory, navigation, and foraging. Because the telencephalon is often associated with spatial memory and navigation tasks, this hypothesis predicts a positive associ...
Article
Evolutionary biologists typically represent clines as spatial gradients in a univariate character (or a principal-component axis) whose mean changes as a function of location along a transect spanning an environmental gradient or ecotone. This univariate approach may obscure the multivariate nature of phenotypic evolution across a landscape. Clines...
Preprint
Full-text available
Damage by parasites is a perpetual challenge for hosts, often leading to the evolution of elaborate mechanisms of avoidance, immunity, or tolerance. Host resistance can evolve via changes in immune protein coding and/or expression. Heritable population differences in gene expression following infection can reveal mechanisms of immune evolution. We...
Article
Basic science is integral to medical education because it teaches future physicians the fundamental principles of biology they need to become lifelong learners and keep up with expanding medical knowledge. One of these fundamental principles is evolution, which has many practical applications in medicine. Consequently, there is increasing interest...
Article
Character displacement was originally defined simply as a pattern – divergence between two species in sympatry but not allopatry – and it was recognized that multiple processes might generate this pattern. However, over time, character displacement has come to be nearly synonymous with the process of adaptive divergence between species caused by se...
Preprint
Full-text available
Major histocompatibility (MHC) genes encode proteins that play a central role in vertebrates’ adaptive immunity to parasites. MHC loci are among the most polymorphic in vertebrates’ genomes, inspiring many studies to identify evolutionary processes driving MHC polymorphism within populations, and divergence between populations. Leading hypotheses i...
Article
Trait-based ecology argues that an understanding of the traits of interactors can enhance the predictability of ecological outcomes. We examine here whether the multidimensional behavioural-trait diversity of communities influences community performance and stability in situ. We created experimental communities of web-building spiders, each with an...
Preprint
Full-text available
Parasites can be a major cause of natural selection on hosts, which consequently evolve a variety of strategies to avoid, eliminate, or tolerate infection. When ecologically similar host populations present disparate infection loads, this natural variation can reveal immunological strategies underlying adaptation to infection and population diverge...
Article
Full-text available
Gene flow is widely thought to homogenize spatially separate populations, eroding effects of divergent selection. The resulting theory of ‘migration-selection balance’ is predicated on a common assumption that all genotypes are equally prone to dispersal. If instead certain genotypes are disproportionately likely to disperse, then migration can act...
Article
Full-text available
Parasite infections are a product of both ecological processes affecting host-parasite encounter rates and evolutionary dynamics affecting host susceptibility. However, few studies examine natural infection variation from both ecological and evolutionary perspectives. Here, we describe the ecological and evolutionary factors generating variation in...