A Biogeographic Perspective on the Evolution of Fire Syndromes in Pine Trees (Pinus: Pinaceae)

Our goals were to explore the relationship between biogeography and the evolution of fire-adaptive syndromes in the genus Pinus. We used a previously published time-calibrated phylogeny and conducted ancestral trait reconstruction to estimate the likely timing of diversification in Pinus, and to determine when fire-adaptive syndromes evolved in the lineage. To explore trait conservation among fire syndromes and to investigate historical biogeography, we constructed ancestral state reconstructions using the program RASP and estimated the degree of conservatism for fire-adapted traits in the program BaTS. Our reconstructions suggest that the Bering land bridge, which connected North America and Asia, probably played a major role in early pine evolution. Our estimates indicated that fire-adaptive syndromes seem to have evolved more frequently in New World taxa and probably are related to the uplift of major North American mountain ranges. Our data suggest that certain geographically widespread adaptations to fire evolved repeatedly, possibly due to localized changes in climate and environment, rather than resulting from large dispersal events of pre-adapted individuals

Human observers differ in ability to perceive insect diversity

Human perception of biological variation is an important and understudied issue in the conservation and management of natural resources. Here, we took a novel approach by asking 1152 participants, primarily college biology students, to score examples of insect mimicry by the number of distinct kinds of animals they saw. Latent class analysis successfully separated participants based on their accuracy of perception as well as demographic information and opinions about biodiversity. Contrary to expectations, factors such as childhood experience (growing up in urban, suburban or rural areas) did not affect the ability to see biodiversity as much as political views (location on a spectrum from liberal to conservative) or the position that biodiversity is important for the health of the environment. We conclude that research into effective measures of biological education should consider the connection between personal views and perceptions of natural variation

Butterflies, inchworms, and plants: revisiting long-standing hypotheses of codiversification

The purpose of this dissertation was to understand how changes in short-term ecological factors have lead to long-term evolutionary consequences, with a particular focus on the diversification of herbivorous insects and the plants they feed on. I begin with a general discussion of current theory on how changes to a species’ niche, or general way of life, can shape evolutionary processes across a broad diversity of organisms, including adaptation, selection, diversification, and hybridization. Additionally, I discuss two important and unresolved questions specifically regarding the diversification of herbivorous insects and discuss how the subsequent three dissertation chapters attempt to address these areas of investigation. In Chapter 1, I investigate the evolutionary history of Neotropical moths in the hyperdiverse genus Eois (Geometridae), with an emphasis on documenting the roles of host conservatism, geography, and elevation in promoting diversification. In Chapter 2, I examine the evolution of secondary defense chemistry in one clade of Piper plants (Radula), the predominant genus that Eois caterpillars feed on. Finally in chapter 3, I elucidate patterns of novel host using Californian butterflies and exotic plants as a model system in an effort to determine the characteristics of herbivores that promote host shifting, which is typically the predominant mechanism by which diversification is thought to occur in herbivorous insect lineages

Table S1. List of species involved in the analysis with their geographic distribution and their fire adaptations. from A biogeographic perspective on the evolution of fire syndromes in pine trees (<i>Pinus</i>: Pinaceae)

This Table provides all of the biogeographic data and fire adaptation information for all of the Pine species included in the analysis. Some Pine species exhibit multiple different fire adaptations, these are all included in the table

Species with more volatile population dynamics are differentially impacted by weather.

Climatic variation has been invoked as an explanation of population dynamics for a variety of taxa. Much work investigating the link between climatic forcings and population fluctuation uses single-taxon case studies. Here, we conduct comparative analyses of a multi-decadal dataset describing population dynamics of 50 co-occurring butterfly species at 10 sites in Northern California. Specifically, we explore the potential commonality of response to weather among species that encompass a gradient of population dynamics via a hierarchical Bayesian modelling framework. Results of this analysis demonstrate that certain weather conditions impact volatile, or irruptive, species differently as compared with relatively stable species. Notably, precipitation-related variables, including indices of the El Niño Southern Oscillation, have a more pronounced impact on the most volatile species. We hypothesize that these variables influence vegetation resource availability, and thus indirectly influence population dynamics of volatile taxa. As one of the first studies to show a common influence of weather among taxa with similar population dynamics, the results presented here suggest new lines of research in the field of biotic-abiotic interactions

Table S1. List of species involved in the analysis with their geographic distribution and their fire adaptations. from A biogeographic perspective on the evolution of fire syndromes in pine trees (<i>Pinus</i>: Pinaceae)

This Table provides all of the biogeographic data and fire adaptation information for all of the Pine species included in the analysis. Some Pine species exhibit multiple different fire adaptations, these are all included in the table

Species with more volatile population dynamics are differentially impacted by weather.

Climatic variation has been invoked as an explanation of population dynamics for a variety of taxa. Much work investigating the link between climatic forcings and population fluctuation uses single-taxon case studies. Here, we conduct comparative analyses of a multi-decadal dataset describing population dynamics of 50 co-occurring butterfly species at 10 sites in Northern California. Specifically, we explore the potential commonality of response to weather among species that encompass a gradient of population dynamics via a hierarchical Bayesian modelling framework. Results of this analysis demonstrate that certain weather conditions impact volatile, or irruptive, species differently as compared with relatively stable species. Notably, precipitation-related variables, including indices of the El Niño Southern Oscillation, have a more pronounced impact on the most volatile species. We hypothesize that these variables influence vegetation resource availability, and thus indirectly influence population dynamics of volatile taxa. As one of the first studies to show a common influence of weather among taxa with similar population dynamics, the results presented here suggest new lines of research in the field of biotic-abiotic interactions

Absence of population structure across elevational gradients despite large phenotypic variation in mountain chickadees (Poecile gambeli)

Montane habitats are characterized by predictably rapid heterogeneity along elevational gradients and are useful for investigating the consequences of environmental heterogeneity for local adaptation and population genetic structure. Foodcaching mountain chickadees inhabit a continuous elevation gradient in the Sierra Nevada, and birds living at harsher, high elevations have better spatial memory ability and exhibit differences in male song structure and female mate preference compared to birds inhabiting milder, low elevations. While high elevation birds breed, on average, two weeks later than low elevation birds, the extent of gene flow between elevations is unknown. Despite phenotypic variation and indirect evidence for local adaptation, population genetic analyses based on 18 073 single nucleotide polymorphisms across three transects of high and low elevation populations provided no evidence for genetic differentiation. Analyses based on individual genotypes revealed no patterns of clustering, pairwise estimates of genetic differentiation (FST, Nei's D) were very low, and AMOVA revealed no evidence for genetic variation structured by transect or by low and high elevation sites within transects. In addition, we found no consistent evidence for strong parallel allele frequency divergence between low and high elevation sites within the three transects. Large elevation-related phenotypic variation may be maintained by strong selection despite gene flow and future work should focus on the mechanisms underlying such variation may be maintained by strong selection despite gene flow and future work should focus on the mechanisms underlying such variation

Data from: Absence of population structure across elevational gradients despite large phenotypic variation in mountain chickadees (Poecile gambeli)

Montane habitats are characterized by predictably rapid heterogeneity along elevational gradients and are useful for investigating the consequences of environmental heterogeneity for local adaptation and population genetic structure. Food-caching mountain chickadees inhabit a continuous elevation gradient in the Sierra Nevada, and birds living at harsher, high elevations have better spatial memory ability and exhibit differences in male song structure and female mate preference compared to birds inhabiting milder, low elevations. While high elevation birds breed, on average, two weeks later than low elevation birds, the extent of gene flow between elevations is unknown. Despite phenotypic variation and indirect evidence for local adaptation, population genetic analyses based on 18 073 single nucleotide polymorphisms across three transects of high and low elevation populations provided no evidence for genetic differentiation. Analyses based on individual genotypes revealed no patterns of clustering, pairwise estimates of genetic differentiation (FST, Nei's D) were very low, and AMOVA revealed no evidence for genetic variation structured by transect or by low and high elevation sites within transects. In addition, we found no consistent evidence for strong parallel allele frequency divergence between low and high elevation sites within the three transects. Large elevation-related phenotypic variation may be maintained by strong selection despite gene flow and future work should focus on the mechanisms underlying such variation