David M. Marsh's research while affiliated with Washington & Lee University and other places

Publications (40)

Article
Full-text available
Climate change poses several challenges to biological communities including changes in the frequency of encounters between closely related congeners as a result of range shifts. When climate change leads to increased hybridization, hybrid dysfunction or genetic swamping may increase extinction risk—particularly in range‐restricted species with low...
Article
Winter cave and mine surveys have been the primary method to monitor status of bat populations but they are not equally effective across regions or species. Many species of bats that roost in rock outcrops during the non-hibernation period are difficult to monitor with existing methods. Visual surveys for bats roosting on talus slopes has been prop...
Article
Winter cave and mine surveys have been the primary method to monitor status of bat populations but they are not equally effective across regions or species. Many species of bats that roost in rock outcrops during the non-hibernation period are difficult to monitor with existing methods. Visual surveys for bats roosting on talus slopes has been prop...
Article
Citizen science holds great promise for collecting useful environmental data over large spatial scales. However, statistical issues that arise in the analysis of citizen science data may be relatively unfamiliar to scientists accustomed to data collected with traditional research methods. In particular, citizen science projects are often designed w...
Article
Understanding the scales over which land use affects animal populations is critical for conservation planning, and it can provide information about the mechanisms that underlie correlations between species distributions and land use. We used a citizen science database of anuran surveys to examine the relationship between road density, land use and...
Conference Paper
Background/Question/Methods Habitat loss, fragmentation, and isolation pose significant threats to pond-breeding amphibians. Anthropogenic influences that contribute to these factors are particularly harmful because the majority of amphibians require two vastly different habitats for completion of their life cycle. We investigated how pond-breedi...
Conference Paper
Background/Question/Methods Habitat loss and fragmentation represent significant threats to amphibians. Fragmentation is particularly harmful because many amphibians migrate between aquatic and terrestrial habitats, and even narrow bands of unsuitable habitat can act as barriers to movement. Additionally, amphibians are slow-moving and prone to r...
Article
Answering large-scale questions in ecology can involve time-consuming data compilation. We show how networks of undergraduate classes can make these projects more manageable and provide an authentic research experience for students. With this approach, we examined the factors associated with plant species richness in US national wildlife refuges. W...
Article
Terrestrial salamander abundance in North American forests is closely associated with forest characteristics, and salamander populations typically decline following timber removal. However, salamander responses to timber harvest vary considerably from one study to the next – some studies have shown limited or no effects whereas others have found ha...
Article
Full-text available
Montane regions can promote allopatric speciation and harbor unique species with small ranges. The southern Appalachians are a biodiversity hotspot for salamanders, and several montane endemics occur in the region. Here, we present the first DNA sequence data for Plethodon sherando, a terrestrial salamander recently discovered in the Blue Ridge Mou...
Article
ABSTRACT Roads through forest habitats reduce the abundance of many animal species. These reductions are often referred to as edge effects and their causes include roadkill, degradation of forest habitat, and changes in biotic interactions. Which of these causes are operating can have important implications for management. Terrestrial salamanders i...
Article
Territoriality has been well-documented in terrestrial plethodontid salamanders. However, most studies of territoriality have focused either on defense of single cover objects or on defense of areas of forest floor. In nature, cover objects tend to occur in groups, and little is known about how cover-object distributions affect territory defense an...
Article
While techniques for sampling pond-breeding amphibians are relatively well-established, comparable meth-ods for stream amphibians are still being developed. Uncertainty about sampling techniques is particularly acute for approaches that involve multiple observers. I evaluated three techniques for sampling stream sala-manders with multiple observers...
Article
Animal and plant population monitoring programs are critical for identifying species at risk, evaluating the effects of management or harvest, and tracking invasive and pest species. Nevertheless, monitoring activities are highly decentralized, which makes it difficult for researchers or conservation planners to get a good general picture of what r...
Article
Confirmation bias is the tendency of observers to see what they expect to see while conducting scientific research. Although confirmation bias has been well-studied by psychologists in the context of qualitative judgments, it has been much less studied with respect to the kinds of quantitative observations made by behavioral biologists. We carried...
Article
Full-text available
Roads can fragment animal populations by reducing gene flow, which can lead to drift and the loss of genetic diversity. One of the principle signatures of reduced gene flow is increased genetic differentiation in isolated populations, and evidence that roads contribute to such differentiation has been reported for several species. We used microsate...
Article
Full-text available
While many studies have examined the barrier effects of large rivers on animal dispersal and gene flow, few Studies have considered the barrier effects of small streams. We used displacement experiments and analyses of genetic population structure to examine the effects of first-order and second-order streams on the dispersal of terrestrial red-bac...
Article
Full-text available
Several recent studies have shown that amphibian populations may exhibit high genetic subdivision in areas with recent fragmentation and urban development. Less is known about the potential for genetic differentiation in continuous habitats. We studied genetic differentiation of red-backed salamanders (Plethodon cinereus) across a 2-km transect thr...
Article
Roads can fragment animal populations by disrupting movement among formerly continuous habitats. Although models have demonstrated that disrupted movement can contribute to long-term extinction, there are few empirical data on the effects of roads on animal movement. We used displacement and homing experiments to determine whether forest roads are...
Article
Although demographic models have become increasingly important tools in plant conservation, few models have considered the implications of seed banks for population persistence. Based on a 15-year study of the threatened herb, Helenium virginicum, we created a stage-class transition matrix to model the population dynamics of the plant. Our goal was...
Article
Most studies of animal behaviour are based on direct observations of behaviour in a natural or laboratory context. While the potential for observation biases has often been discussed, there have been few quantitative analyses of the kinds of biases that may affect behavioural data. We used multiple observers of aggression and foraging behaviour in...
Article
The ability of animal species to disperse through matrix habitats is likely to have important implications for species' responses to habitat fragmentation. Within frag-mented forests, open fields are among the most common matrix habitats. However, few empirical studies have measured the effects of open habitats on dispersal success of forest-dwelli...
Article
One of the major effects of deforestation is the creation of numerous edge zones where remaining forest meets nonforest habitat. At this interface, edge effects on forest habitats can include altered abiotic conditions, changes in rates of competition and predation, and altered community structure. While the edge effects resulting from clear-cuts a...
Article
Arrays of wood cover boards are useful tools for studying and monitoring plethodontid salamander populations. However, little is known about the biases inherent in monitoring data collected from such arrays. We used Red-Backed Salamanders, Plethodon cinereus, to test for two potential biases associated with use of wood cover board arrays. First, we...
Article
In our essay on amphibian metapopulation dynamics (Marsh & Trenham 2001), we recommended amphibi-ans as "prime candidates" for egg and larval transloca-tion programs. We contended that translocation of am-phibians has been successful in some cases (e.g., Zvirgzds et al. 1995; Denton et al. 1997) and might be the best op-tion for preserving amphibia...
Article
The magnitude of population fluctuations can affect the power of monitoring programs and the calculation of extinction risk. Because amphibian populations may be experiencing worldwide declines, understanding population fluctuations in amphibians is particularly important. I conducted a meta-analysis of population fluctuations in amphibian time ser...
Article
Population responses to variable environments can result from individual behavior (i.e., dispersal and habitat selection) or demography (i.e., changes in birth and death rates). Distinguishing behavioral from demographic responses to environmental variability has important implications for interpretation of spatial patterns and projections of popul...
Article
Because oviposition site selection is often studied in a single ecological context, little is known about flexibility in oviposition strategies. We studied the oviposition site selection strategies of túngara frogs (Physalaemus pustulosus) with respect to conspecific eggs and larvae in two different ecological contexts-arrays of artificial ponds an...
Article
In many respects, amphibian spatial dynamics resemble classical metapopulation models, in which subpopulations in breeding ponds blink in and out of existence and extinction and colonization rates are functions of pond spatial arrangement. This “ponds-as-patches” view of amphibian spatial dynamics is useful in several respects. First, it highlights...
Article
In many respects, amphibian spatial dynamics resemble classical metapopulation models, in which subpopulations in breeding ponds blink in and out of existence and extinction and colonization rates are functions of pond spatial arrangement. This "ponds-as-patches" view of amphibian spatial dynamics is useful in several respects. First, it highlights...
Article
Though many amphibians breed in response to rainfall, rainfall can create substantial risks as well as benefits. For species that breed in ephemeral ponds and puddles, heavy rainfall can create many “false” ponds that quickly desiccate, particularly in wet years. As a result, nightly responses to rainfall may vary depending on seasonal or yearly ra...
Article
Full-text available
Habitat and resource distributions can influence the movement and aggregation of individuals and thus have important effects on breeding behavior and ecology. Though amphibians have been model systems for the study of breeding behavior and sexual selection, most studies have examined breeding behavior within a single pond. As a result, little is kn...
Article
1. Recent theoretical and empirical research has shown that habitat isolation can have strong effects on patterns of abundance and population dynamics of animals. Effects of habitat patch isolation may be particularly strong in taxa such as amphibians, which may have limited dispersal abilities and yet rely on breeding habitats that are variable in...
Article
We used visual transect surveys to study the effects of forest fragmentation on abundance of two species of Leptodactylid frogs in an Andean forest of northern Ecuador. We measured the abundances of Eleutherodactylus chloronatus and E. trepidotus at various distances from the forest edge in one large forest patch (200 ha) and four adjacent forest f...

Citations

... Our samples from P. cinereus came from the same habitat patches as those from P. nettingi and, as such, might also be expected to exhibit fairly low levels of genetic variation. In fact, in a similar comparative study, Page et al. (2020) actually found P. cinereus to have lower levels of genetic diversity than another small-ranged, Appalachian mountain-top plethodontid salamander, P. hubrichti. However, based on our analyses of the microsatellite data, the levels of genetic variation we observed for P. cinereus from our sampled patches are substantially higher than those observed for P. nettingi (Table 1), and similar to values reported from P. cinereus from fragmented forest patches elsewhere in the species' range, i.e., Indiana (Jordan et al. 2009), Ohio (Wilk et al. 2020) and Canada (Noël et al. 2007;Noël and Lapointe 2010). ...
... These challenges have led to new methods in monitoring this rock-roosting species. In some areas of the Eastern Small-footed Bat's range, flipping rocks or searching rock crevices with flashlights has proved to be a successful way to find individuals in their diurnal summer roosts (Moosman et al. 2020). ...
... in research and conservation(Cooper et al., 2021;Marsh & Cosentino, 2019;McKinley et al., 2015;Westgate et al., 2015). Research suggests that actively involving the public in science can improve biolog-ical knowledge, conservation awareness and encourage participation in decision-making processes (Aceves-Bueno et al., 2015; Shirk et al., 2012). ...
... Surprisingly, we found that populations of both spring and summer breeding species, as well as species that overwinter in soil and in stream beds, were sensitive to observed winter severity, with warmer temperatures and increasing days of snow cover increasing occupancy for many species. This illustrates that changing winter conditions may have long-term consequences for anuran species across a range of breeding phenology and life history characteristics across large spatial scales, in contrast to other investigations (Gibbs & Breisch, 2001;Marsh et al., 2017). ...
... They reproduce repeatedly over multiple seasons to make temporally fine-grained environments or move wider across habitats with different conditions to make spatially fine-grained environments (Figure 7). For these reasons, iteroparity (Hopper, 1999;Stearns, 1992) and dispersal or migration (metapopulation structure: Hanski, 1999;Levin, 1974;Marsh & Trenham, 2001) have evolved in many species. Both activities are costly in terms F I G U R E 7 Within-generation diversified bet-hedging. ...
... Although many amphibians often are found in new ponds and have better larval performance in these habitats, oviposition preference for newly filled ponds has not been demonstrated (Wilbur, 1980;Alford and Wilbur, 1985;Wilbur and Alford 1985;Morin 1990;Murphy, 2003;Church, 2008). In a similar study, ovipositing T´ungara Frogs, Physalaemus pustulosus, in Panama did not prefer newly filled ponds two, four, and eight weeks younger than paired old water ponds (Fegraus and Marsh, 2000). Larval growth and survival did not differ between old and new ponds, however, suggesting no selective advantage to breed in new ponds. ...
... Citizen science efforts have been used to document trends in anuran occupancy as part of the North American Amphibian Monitoring Program (Cosentino et al. 2014;Weir et al. 2014;Villena et al. 2016). Herpetological statewide atlases have been significantly aided by citizen scientists (Cunningham et al. 2012;Gibbs et al. 2007;Jensen et al. 2008;Price and Dorcas 2011). ...
... The Appalachian mountains are a biodiversity hotspot for plethodontid salamanders, the largest genus of salamanders in North America with > 50 recognized species (Rissler and Smith 2010;Bayer et al. 2012). Many species of Plethodon have limited dispersal ability and exhibit strong site fidelity, which can promote isolation and local speciation, resulting in species endemic to a single mountaintop or mountain range (Highton 1995;Carpenter et al. 2001;Wiens et al. 2006;Cabe et al. 2007;Marsh et al. 2008;Kozak and Wiens 2010). ...
... Class modules can also be developed to incorporate long-term components. These have the added benefit of exposing students to realistic hypothesis-testing and data-collection activities, which is otherwise often absent in science lab courses (Hoopes et al., 2013). Furthermore, the use of students can increase civic attitudes as well as aid in management or restoration goals directly (Bruce et al., 2014 Alternatively, the enthusiasm of the general public can be leveraged for the collection and analysis of long-term data (e.g., "citizen science"), facilitating the development of longitudinal studies (Conrad & Hilchey, 2011). ...
... Although most studies agree that clearcutting can have strong effects on terrestrial salamanders (DeMaynadier and Hunter, 1995), the results of other types of harvesting are more variable. A review of 108 species and treatment combinations from 24 studies concluded that complete overstory removal (e.g., clearcut) has a greater impact than partial overstory removal (e.g., single-tree, group selection, shelterwood, or forest thinning) on terrestrial salamanders (62% mean decline and 29% mean decline respectively), but that salamander numbers almost always declined following timber removal (Tilghman et al. 2012). Studies of shelterwood harvests have produced variable results, with some studies finding strong effects of the initial shelterwood cut on salamander abundance Haas 1999, Knapp et al. 2003) and some reporting little to no effects of the initial cut (Cantrell et al. 2013, Macneil and Williams 2014, Mahoney et al. 2016. ...