The study of host shifts by herbivorous insects has played an important role in evolutionary biology, contributing to research in coevolution, ecological speciation, and adaptive radiation. As invasive plants become more abundant in many ecosystems,
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.
Myriad unexplored mechanisms potentially drive ecological speciation and could help explain global variation in diversity. Here, we develop a novel hypothesis focused on variation in biotic, chemical, and physical properties of soil as a factor contributing to diversification in communities of plants and animals. The Soil Mosaic Hypothesis (SMH) suggests that differences in soil attributes can affect intraspecific variation in phytochemistry, leading to cascading ecological and evolutionary effects on higher trophic levels. To illustrate the potential importance of the SMH, we examine three underlying ideas: (1) plant species and species assemblages shift over time, exposing them to novel soil environments, which can lead to genetic differentiation; (2) differences in soil properties can alter phytochemistry via plasticity and local adaptation; (3) phytochemistry can drive herbivore diversification via divergent natural selection (i.e. ecological speciation). The SMH provides insight into the process of diversification in a variety of landscapes and at a variety of scales and may inform analyses of diversification at local, regional, and global scales.
Abstract. 1. Ecologists often make predictions about community richness and diversity using climate variables that include seasonal precipitation totals and mean daily temperatures. While means and totals can be effective predictors to a certain extent, the complexities of faunal-climate relationships might be over-simplified through the use of coarse-grained variables.2. The goal of this study was to investigate less commonly studied climate variables, including indices of intra-annual variation in the timing and intensity of precipitation events that might be used to predict butterfly richness across an elevational gradient. Data from a long-term, single-observer dataset at four sites in California were examined with Bayesian model averaging and structural equation modelling. Species-specific responses to climate were compared with community responses at each site.3. At lower elevations, it was found that the relative importance of climate variables shifted towards temporal patterns of precipitation, including the timing of the first storm event and the annual number of precipitation events. Heterogeneity among sites was apparent in the importance of specific weather variables, and temporal trends (across years) were detected for a small number of variables. Species-specific results paralleled those obtained from analysis of species richness, thus suggesting a commonality of response to climate across site-specific assemblages.4. Models were improved by inclusion of the Pacific Decadal Oscillation and El Niño-Southern Oscillation indices, indicating that regional variables can profitably be included in faunal-climate relationship analyses. These results emphasise the need for researchers to examine climate variables beyond the most readily summarised means and totals.
Managing vast federal public lands governed by multiple land use policies creates challenges when demographic data on at-risk species are lacking. The U.S. Bureau of Land Management Cedar City Field Office used this project in the Black Mountains (Utah) to inform vegetation management supporting at-risk greater sage-grouse and Utah prairie dog planning. Ecological systems were mapped from satellite remote sensing imagery and used to model species habitat suitability under two levels of management activity (custodial, preferred) and climate scenarios for historic and two global circulation models. Spatial state-and-transition models of ecological systems were simulated for all six scenarios up to 60 years while coupled with expert-developed habitat suitability indices. All ecological systems are at least moderately departed from reference conditions in 2012, whereas habitat suitability was 50.5% and 48.4% for sage-grouse and prairie dog, respectively. Management actions replaced non-native annual grasslands with perennial grasses, removed conifers, and controlled exotic forbs. The drier climate most affected ecological departure and prairie dog habitat suitability at 30 years only. Different climates influenced spatial patterns of sage-grouse habitat suitability, but nonspatial values were unchanged. Climate impacts on fire, vegetation succession, and restoration explain many results. Front-loading restoration is predicted to benefit under future drier climate.
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