Treesearch

Background: As it becomes increasingly possible to obtain DNA sequences of orthologous genes from diverse sets of taxa, species trees are frequently being inferred from multilocus data. However, the behavior of many methods for performing this inference has remained largely unexplored. Some methods have been proven to be consistent given certain evolutionary models, whereas others rely on criteria that, although appropriate for many parameter values, have peculiar zones of the parameter space in which they fail to converge on the correct estimate as data sets increase in size. Results:...

Deploying well-adapted and ecologically appropriate plant materials is a core component of successful restoration projects. We have developed generalized provisional seed zones that can be applied to any plant species in the United States to help guide seed movement. These seed zones are based on the intersection of high-resolution climatic data for winter minimum temperature and aridity (as measured by annual heat : moisture index), each classified into discrete bands. This results in the delineation of 64 provisional seed zones for the continental United States. These zones represent...

The velocity of species dispersal post-last glacial maximum (LGM) is an interesting question from both paleo-historical and contemporary perspectives. The apparent time lag between a location’s climate becoming suitable for a given species and that species’ arrival at that location has important implications for our understanding of the relationship between climate variables such as temperature and moisture and the dispersal ability of plants. Our knowledge of species dispersal rates underlies assumptions required for the interpretation of pollen and sediment records, biogeochemical...

Warmer and drier climate over the past few decades has brought larger fire sizes and increased annual area burned in forested ecosystems of western North America, and continued increases in annual area burned are expected due to climate change. As warming continues, fires may also increase in severity and produce larger contiguous patches of severely burned areas. We used remotely sensed burn-severity data from 125 fires in the northern Cascade Range of Washington, USA, to explore relationships between fire size, severity, and the spatial pattern of severity. We examined relationships...

Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density...

We may expect butterflies as ectotherms to have particularly active lifehistory stages that occur in the warmest and lightest times of the year; however, there are temperate species that are active when climatic conditions seem unfavourable and photoperiod short, such as the Taylor’s checkerspot (Euphydryas editha taylori). For such species, studies suggest that even subtle changes to microclimate can potentially impact populations. Thus, understanding how in situ variations in microclimate influence the Taylor’s checkerspot butterfly could provide much needed insights into more effective...

The conversion rate of flowers into fruit in C. montanum at two sites over four seasons was 52-85%, unusually high for a food mimic orchid. Comparative measurements of the trap-like labellum of C. montanum showed it was intermediate in size compared to measurements of six other Cypripedium spp. found in North America and China. While visitors to flowers of C. montanum represented three insect orders, at two sites, over four seasons only small- to medium-sized, solitary bees (5-10 mm in length) carried the pollen massulae. Bee-visitation occurred at both sites and began within 24-48 hours...

Biological invasions create complex ecological and societal issues worldwide. Most of the knowledge about invasions comes only from successful invaders, but less is known about which processes determine the differential success of invasions. In this review, we develop a framework to identify the main dimensions driving the success and failure of invaders, including human influences, characteristics of the invader, and biotic interactions. We apply this framework by contrasting hypotheses and available evidence to explain variability in invasion success for 12 salmonids introduced to Chile....

Urban landscape restoration and conservation initiatives are challenged by financial and other constraints. Consequently, these initiatives are increasingly reliant on volunteer stewards. Knowledge of why people volunteer to restore and conserve urban ecosystems can help practitioners enhance volunteering as a social-ecological process that is mutually beneficial to landscapes and people. We included two open-ended questions about why people volunteer and what they perceive as benefits of volunteering, in a survey of volunteers for urban landscape restoration and conservation in Seattle,...

Multiple species of annual grasses are invading sagebrush-steppe communities throughout the western United States. Most research has focused on dominant species such as Bromus tectorum (cheatgrass), yet other, less studied annual grasses such as Taeniatherum caput-medusae (medusahead) and Ventenata dubia (ventenata) are spreading rapidly. Future precipitation regimes are expected to have less frequent but more intense rain events, which may affect soil moisture availability and favor these ‘newer’ invasives over cheatgrass. We conducted a full factorial, growth chamber study examining the...