Limpets and Their Algal Epibionts: Costs and Benefits of Acrosiphonia

Epibiont and basibiont relationships can have positive and negative effects on both organisms involved, ranging in intensity from minor to major effects. Limpets of species Lottia pelta are commonly found with two algal species growing on their backs, Ulva lactuca and Acrosiphonia spp. Previous research has shown that basibionts (substrate organism) and epibionts (organism growing on the surface) have complex interactions that can be positive, negative, or neutral. A force transducer and flume were used to measure the drag forces experienced by a limpet at various water velocities. Presence of either epiphyte significantly increased limpet drag. Acrosiphonia produced a greater drag effect than U. lactuca, increasing the force substantially. When dropped in a tank, limpets with algal growth landed foot-down significantly more often than limpets without algal growth. Acrosiphonia spp. had a greater effect than Ulva lactuca. Lastly, limpets in a wind tunnel with algal growth (especially Acrosiphonia) had cooler body temperatures than limpets without algal growth. In conclusion, the effects on the basibiont of this relationship were found to be both positive and negative

Developing a predictive model of the autecology of the spruce-fir moss spider, Microhexura montivaga Crosby and Bishop 1925 (Araneae: Dipluridae)

The spruce-fir moss spider (Microhexura montivaga) is a federally endangered species of spider found only in the high-elevation Southern Appalachian spruce-fir forests on North-facing slopes underneath moss mats. Despite this fact, little is known about some of the basic ecology of the spider, more specifically the characteristics of the habitat found underneath the moss mats. The goals of this project was to determine the temperature and humidity parameters of the microhabitat conditions around known spider locations, catalogue what other species live there, and use predictive mathematical models created in the Maxent software to estimate past and current locations of potential habitats and identify the key environmental factors that drive such a model. iButton temperature and humidity data loggers placed at Mt. Lyn-Lowry, Browning Knob, Whitetop Mountain and Mt. Rogers (a range that encompasses all metapopulations). Lyn-Lowry and Browning Knob are located in the Plott Balsam range in North Carolina. Whitetop Mountain and Mt. Rogers are located in the Mt. Rogers National Recreation Area in Virginia. No statistically significant differences in daily maximum or minimum temperature between positive and negative presence sites, among metapopulations, or individual sites. A potential set of temperature conversion factors were calculated using percent change for temperature by comparing the collected data, a local weather station, and a U.S. Fish and Wildlife Service deployed HOBO data logger mounted in a tree. Soil samples collected from Blackrock Mountain in the Plott Balsams yielded 2039 individuals comprising 11 orders, with Collembola and Acari being by far the most abundant; this is important as these orders have been hypothesized to be the primary prey items of M. montivaga. Maxent models show the current potential range as well as historical models of the last interglacial period and glacial maximum. Maxent models use presence only data and environmental factors to estimate potential habitat. Range during the last glacial maximum was greater than present range while the range during the last interglacial period was less than present range according to the models. They also include potential range expansion and retraction patterns. All models were heavily driven by temperature environmental layers, in particular those dealing with temperature maximums. This research provides a number of potential applications for the conservation and management of M. montivaga, such as using collected data to determine conversion factors for temperature data between microhabitat measurements and larger scale measuring methods, such as weather stations. For example, HOBO data loggers mounted in trees measure maximum daily temperature higher by 83.5% compared to microhabitat measurements. This allows for large scale monitoring can be done without having to actually measure the temperatures underneath the moss mats. It is hoped that this research, along with the continuing work of U.S. Fish and Wildlife Service, will contribute to a much more positive outlook for this endangered species

UNDERSTANDING AMPHIBIAN DISTRIBUTIONS, POPULATION DYNAMICS, AND POPULATION CONNECTIVITY BY USING ECOLOGICAL MODELLING AND GENETICS

One principle question in ecology is how temporal and spatial environmental heterogeneity influences species’ ranges and connectivity of populations within the range. I aimed to integrate across disciplines to build a greater understanding of the impact of environmental heterogeneity on a variety of North American cold-adapted amphibian species. First, we found the last Northern Leopard Frog population in Washington is structured as three subpopulations, even at very small spatial scale (<4 km2), with grouping occurring along previously determined hydrological units. We informed conservation efforts using the subpopulations and migration rates by creating a meta-population viability analysis. Second, we evaluated landscape influences on population connectivity of the Columbia Spotted Frog under multiple sampling scenarios, and found forest reduced gene flow compared to other landscape types. Third, we conducted a systematic literature review and found that dispersal is rarely incorporated in species’ range research. We also conceptualized the consequences of not including dispersal. Fourth, using species distribution modeling, we found that human impact is one of the driving factors, along with climate, for delineating the range of six species. This highlights the need for researchers to move beyond climate-only estimates. We found that under more severe climate change, ranges will likely contract, and population extinction will occur at the southern edge. Under less sever climate change models, some species ranges were predicted to increase due to northward expansion occurring faster than rates of southern habitat loss. These findings highlight the importance of models that incorporate more realistic biological information add important resolution to range predictions. Throughout this work, we have integrated landscape ecology, computational modelling, and genetics to address questions of connectivity and range dynamics. We hope that these results are instrumental in the guidance of conservation decisions for cold-adapted amphibians, while also advancing methodologies for use in a wide-array of systems

Evaluating the Influence of Beaver Ponds on Nonnative Brook Trout in Idaho Streams Using Species Distribution Models

Beavers (Castor canadensis) alter the hydrologic, biotic, and geomorphic processes of stream systems in ways that benefit many aquatic species. As a result, beaver relocation is increasingly being used as a stream restoration tool. However, beaver impoundments could also facilitate the spread of nonnative fish species. This study aims to evaluate the influence of beaver ponds on nonnative brook trout (Salvelinus fontinalis) in Idaho. We will use species distribution modelling techniques to evaluate the role of beaver ponds, relative to other environmental variables, in determining the observed distributions of brook trout. Specifically, we will utilize the Beaver Restoration Analysis Tool (BRAT) outputs, IDFG brook trout distribution data, a valley confinement algorithm, NHDPlusV2 data, and other existing environmental data layers. If the best model includes beaver ponds as a key variable, while statistically controlling for other environmental and geographic effects, we will conclude beaver ponds do impact brook trout distribution. Additionally, we will provisionally recommend that caution is needed when beaver reintroductions are used as a conservation tool in Idaho, as such introductions may facilitate expansion of brook trout. If we find that beaver ponds are not a key variable, then we will suggest that nonnative brook trout spread may not be a major concern for future beaver restoration efforts

Integration of dispersal data into distribution modeling: what have we done and what have we learned?

Inclusion of dispersal data in models of species’ distributions in response to environmental change has been advocated for more than 15 years. We investigated whether there has been a shift in recent publications to include dispersal processes and how dispersal estimates explicitly change the conclusions of analyses. To address this question, we conducted a systemic review of the literature to assess what kinds of dispersal data and methods are being included in species distribution models across taxa. We collected metadata on 6,406 publications, 907 of which included dispersal data. The proportion of papers that included dispersal data in estimates of the species’ range increased from 8% to 20% from 1991 to 2017. Evaluation of a subsample of 200 papers showed no evidence for differences in taxa studied between dispersal and non-dispersal publications, with most studies focused on North America or Europe. Dispersal was incorporated at a higher frequency in studies from South America, Africa, and island systems. We found that forecasting models predicting range shifts with climate change rarely used dispersal data, but when they did, range shift projections were greatly affected. Our simulation models, in which a range of dispersal estimates were included, showed that projections were greatly influenced by dispersal distance assumptions. We summarize best practices for future research on distributions, including potential methodologies for dispersal integration and highlight the problems if dispersal is ignored

Integration of dispersal data into distribution modeling: what have we done and what have we learned?

Inclusion of dispersal data in models of species’ distributions in response to environmental change has been advocated for more than 15 years. We investigated whether there has been a shift in recent publications to include dispersal processes and how dispersal estimates explicitly change the conclusions of analyses. To address this question, we conducted a systemic review of the literature to assess what kinds of dispersal data and methods are being included in species distribution models across taxa. We collected metadata on 6,406 publications, 907 of which included dispersal data. The proportion of papers that included dispersal data in estimates of the species’ range increased from 8% to 20% from 1991 to 2017. Evaluation of a subsample of 200 papers showed no evidence for differences in taxa studied between dispersal and non-dispersal publications, with most studies focused on North America or Europe. Dispersal was incorporated at a higher frequency in studies from South America, Africa, and island systems. We found that forecasting models predicting range shifts with climate change rarely used dispersal data, but when they did, range shift projections were greatly affected. Our simulation models, in which a range of dispersal estimates were included, showed that projections were greatly influenced by dispersal distance assumptions. We summarize best practices for future research on distributions, including potential methodologies for dispersal integration and highlight the problems if dispersal is ignored

RALUNoSibs_GPS

Population locations