Biodiversity, Conservation, Ecology & Evolution

Convergent Evolution of Opsin Gene Expression Across Multiple African Cichlid Radiations

Authors: Kelly O'Quin, Christopher Hofmann, Hans Hofmann, and Karen Carleton
Department or Program: BEES
Presented by: Kelly O'Quin
Abstract: Convergent Evolution of Opsin Gene Expression Across Multiple African Cichlid Radiations

GENOME-WIDE LEVELS OF INTROGRESSION AND DIVERGENCE ACROSS MEXICAN TOWHEE HYBRID ZONES

Authors: Sarah E Kingston; William F Fagan; Michael J Braun
Department or Program: BEES
Presented by: Sarah E Kingston
Abstract: Hybrid zones are unique interfaces that can help us understand both population level and species level evolutionary processes. Stable regions of hybridization between two species of towhee, Pipilo maculatus (spotted towhee) and P. ocai (collared towhee), in Mexico have been previously delineated using morphological characters and isozyme loci. There are two main hybrid gradients; where these two gradients intersect, the two parental forms live sympatrically without hybridizing. Unraveling the architecture of this hybrid complex on a genomic level can offer insight into the broader implications of interspecies gene flow. Specifically, testing the porosity of the species boundary can help us assess the evolutionary importance of interspecies gene flow between these lineages. Specimens of P. maculatus, P. ocai, and their hybrids have been collected along the Teziutlán (~1200km, 11 locations, 167 total specimens) and Transvolcanic (~700km, 10 sites, 295 total specimens) gradients. The AFLP assay (genome survey) was run on the genomic DNA. Individuals were also sequenced at the mtDNA locus ND2 (1027 bp). Multi-locus analyses reveal not only geographic differentiation among parental types, but also divergence of populations within the areas of hybridization. Cline parameters (i.e. width, center) were estimated from the AFLP loci in order to compare among loci and compile a genomic distribution of parameters. The analysis revealed a variety of cline shapes, not just steep, concordant clines. The variation in cline parameters and a signature of bi-directional introgression across the species boundary suggests that some portion of loci in the genome may be free to cross porous species boundaries while other loci may be restricted by selective pressure. In combination, these results suggest gene exchange between species may be an important factor along the evolutionary trajectory of lineages.

POPULATION EFFECTS OF RESOURCE ALLOCATION STRATEGIES IN ASEXUALLY REPRODUCING ANNELIDS: SIZE DOES MATTER!

Authors: E.E. Zattara, P. Casanovas, A.E. Bely
Department or Program: BIOL
Presented by: Paula Casanovas
Abstract: Deciding between growth and reproduction is fundamental in determining life history strategies. How many resources are allocated to somatic growth and/or reproduction is a developmental decision with consequences affecting a species' ecological context. We explored resource allocation strategies and their effects on population growth using an in silico system modeled after naidid annelids, a group of segmented worms that reproduce asexually. Naidines grow by adding segments at their tail-end; when food is "fission zone", splitting the worm in two daughter individuals. How are resources allocated to either terminal growth or fission? We proposed two hypotheses; in the first, a fixed proportion of available resources is devoted to each process. In the second, the proportion varies with the worm's length. We built a computer model based in individual growth to generate predictions under each hypothesis. Our model predicts that under the first hypothesis, populations will increase at a rate dependent solely on available energy, irrespective of where along the body is a fission zone placed. Under the second however, locating a fission zone within certain ranges greatly enhances the population increase rate. We measured location and distribution of fission zones in real worm populations and found that they are placed at a specific level, within the range predicted under the variable-proportion hypothesis. We conclude that naidid worms do not use a fixed proportion allocation strategy, varying instead the proportion depending on each individual’s size.

Testing for Sexually Antagonistic Coevolution in Temperate Leiobunine Harvestmen

Authors: Mercedes Burns, Jeffrey Shultz
Department or Program: BEES
Presented by: Mercedes Burns
Abstract: Species-specific variation in genitalia is a pervasive theme in arthropod evolutionary biology, but researchers have differed on the sexual selection paradigms that may be involved in maintaining complicated genital structures. Some structures appear to be capable of increasing male reproductive success through coercion of females. The potential for coercion may produce selective pressure for females to present more discriminatory or defensive phenotypes, which could be reciprocated by the evolution of additional coercive features in the male. This escalating pattern of conflict is termed sexually antagonistic coevolution or a sexual arms race. Leiobunine harvestmen, members of the arachnid order Opiliones, occur throughout eastern North America and display a variety of genital morphologies—ranging from sacculate penises with glands that deliver an enticing nuptial gift to females during mating, to lanceolate forms that appear to be modified to force open the female genital operculum, plus intermediates. Coercive genital phenotypes are accompanied by palpal modifications for increased clasping strength, which could increase a male's ability to secure forced copulations. Using a phylogeny constructed from nuclear, ribosomal, and mitochondrial genes, we find that leiobunine species of eastern North America are closely related. Furthermore, the loss of penile sacs has occurred at least four times among the lineage of leiobunine harvestmen, and intermediate forms of male armament and female defense are seen in members of several species groups. These findings are consistent with the presence of a sexual arms race in temperate leiobunine opilionids. Further research will seek to correlate antagonistic characters using phylogenetic comparative methods to contrast behavior and genital biomechanics independent of phylogeny.

The Use of Population Viability Analysis in the Recovery of Plant Species Listed under the U.S. Endangered Species Act

Authors: Sara Zeigler and Maile Neel
Department or Program: GEOG
Presented by: Sara Zeigler
Abstract: Studies have shown that populations of endangered species listed under the U.S. Endangered Species Act of 1979 were more likely to be characterized as “improving” if the species had clear, quantitative, biologically-based recovery criteria. However, most species either do not have clear criteria or have criteria that have been criticized for not being biologically-based. Population viability analysis (PVA) has been recommended as a tool for using species-specific demographic data to inform recovery criteria and management goals. The objectives of this study are (1) to examine PVA studies for both endangered and non-endangered plant species across the world to determine trends in how such models have been used and constructed in the past and (2) to determine if such studies could be used to inform models for endangered plant species in the U.S. for which information gaps in demographic data exist. Using ISI’s Web of Science database and Google Scholar we found 223 PVA studies discussing 246 plant species. Many of the PVAs were constructed from age- or stage based models and contained components for simulating the impact of threats and/or management options on species’ persistence. We also found that the results of PVAs and their sensitivity analyses were highly species and context dependent. PVA results changed dramatically depending on the underlying time and location demographic data were collected. Results also depended on the components used within the PVA models such as stochasticity and density dependence. Finally, sensitivity analyses, which highlighted the most important life-history stages for the persistence of a population or species, were dependent on the type of sensitivity methodology used, growth rate of the population, and components included in the model. We conclude that, although PVA may be an important tool for informing biologically-based recovery criteria for endangered species, conservationists will likely need to continue to base such models on demographic studies specific to individual species and even populations.

The role of host-hybridization in the host-associated genetic divergence of the holly leafminer Phytomyza glabricola

Authors: Julie Hebert, Sonja Scheffer, David Hawthorne
Department or Program: BEES
Presented by: Julie Hebert
Abstract: Phytophagous insects are extremely diverse, and one major factor contributing to this diversity involves changes in host use. Host races, populations of a species found on different hosts with limited gene flow between them, are often studied to determine the underlying mechanisms for speciation, and therefore diversity in insect lineages. This study examines potential host race formation in Phytomyza glabricola, a leafmining fly native to eastern North America that feeds on two native species of holly, Ilex glabra and I. coriacea. Elongation factor 1 alpha (EF1α) was sequenced in flies from available hosts in seven locations across their range. Significant differences in genetic structure were found in flies from different hosts. However there were several shared haplotypes, indicating limited gene flow. Significant differences in genetic structure were also found between populations from different locations. These results indicate P. glabricola does consist of host races. In addition, environmental factors, such as hybridization in the host plants, may be affecting the rate of gene flow differently in different locations, indicating a geographic mosaic of genetic divergence in these flies.

The Power of Wright’s F(st) and Jost’s D to Detect Recent Fragmentation Events

Authors: Michael W. Lloyd and Maile C. Neel
Department or Program: PSLA
Presented by: Michael Lloyd
Abstract: Habitat loss and fragmentation are considered to be the most imminent threats to biological diversity worldwide and thus are fundamental issues in conservation biology. Increased isolation alone has been implicated as a driver of negative impacts in populations associated with fragmented landscapes. Genetic monitoring and the use of measures of genetic differentiation have been proposed as solution to detect changes in landscape connectivity. Our goal was to evaluate whether or not genetic differentiation measured by Wright’s F(st) and Jost’s D is sensitive enough to detect recent fragmentation events across a range of effective population sizes and sampling regimes. We constructed an individual based model, which varied effective population size, the presence or absence of overlapping generations, and the presence or absence of population sub-structuring to assess this.

A nursery pollinator as a selective agent on floral traits through oviposition behavior

Authors: A.A.R. Kula, M.R. Dudash and C.B. Fenster
Department or Program: BEES
Presented by: Abby Kula
Abstract: There is much controversy surrounding the role of pollinators in the evolution of floral form, and recently florivores, frugivores and herbivores have been shown to select for floral traits. Because nursery pollinators play a dual role as pollinators and seed predators, they might exert conflicting selection pressures on floral traits, allowing unique insight into the relative selection pressures based on pollination and florivory or frugivory in the evolution of the floral phenotype. If nursery pollinators show oviposition preference on flowers with certain floral traits, a mechanism of selection through seed predation will be demonstrated. To determine the attractiveness of floral traits of Silene stellata for oviposition by the nursery pollinator, Hadena ectypa, several flowers per flagged plant were measured. The number of eggs laid on flowers was counted at the time of measurement. Means of floral measurements and eggs per flower were calculated for each plant. Multiple regression of oviposition (number of eggs per flower observed on a plant) on six floral measurements, stem height, and number of stems was significant for tube length (length from petal inflection to the nectary at the base of the ovary). This study indicates plants with flowers with longer tubes are more attractive to ovipositing moths. At the whole plant level, if plants with longer floral tubes have higher fruit predation (assuming higher oviposition rates results in higher predation), these plants will have lower reproductive output resulting in a net negative interaction with the nursery pollinator.

A network analysis approach to exploring the social structure of African ungulates

Authors: Leah Carpenter, Katerina Thompson, Mary Ann Ottinger
Department or Program: BEES
Presented by: Leah Carpenter
Abstract: Historically, studies of social behavior have focused on individuals or dyads, seldom taking a holistic approach that integrates information from an entire social group. Since the 1950’s the analytical tools have become available to quantitatively describe groups as a whole through their pattern of social relationships. This approach is central to social networks analysis. Within the past decade, social networks analyses have been adapted for the study of animal behavior. These applications provide the methods for investigating interactions at the individual, community, population and inter-population levels. In this study, social networks of herds of two species of African ungulates, roan antelope (Hippotragus equinus; n=10), and addra gazelle (Nanger dama; n=11), were constructed from data on direct social and agonistic interactions and spatial associations. The two species shared some features in their social structures, such as the centrality of dominant males. However, there were species differences relative to social subgroups and core versus peripheral actors, especially in agonistic interactions that were largely dependent on actor age. The social structure of these two ungulate groups as well as the variation in social structure and behavior between species hold interesting theoretical questions as well as practical implications for captive management of these species.

Won't you be my Neighbor: Community Interactions Between Sirex Noctilio and a Native Pine Community Assemblage

Authors: Brian Thompson, Dan Gruner
Department or Program: ENTM
Presented by: Brian Thompson
Abstract: Invasive species are one of the greatest threats to forests worldwide. Understanding the local processes of competition, predation and facilitation during these invasions is central to predicting the impact of invading species. The European sawfly, Sirex noctilio, is a recent invader to North America that, with its broad host range (>12 Pinus species worldwide) and an ability to attack healthy trees, is particularly threatening to North American conifers. It remains unclear whether Sirex will become devastating, as it has in pine plantations in the Southern Hemisphere, or whether it will it will be benign, as it is in native Eurasian forests. Among the many differences between past introductions and Sirex’s native forests, is the presence of a diverse assemblage of co-evolved interacting species. A pairwise field trial of Sirex attacked-vs- control Red pines shows that while Sirex is new to North America (<5 years) it elicits a strong response from some members of the North American insect community. Xylotrechus colonus, two native Siricids, and numerous parasitoid species, including Ibalia leucospoides, a known parasitoid of Sirex noctilio, were significantly more attracted to the attacked trees than the control. This attraction precludes interactions that could be either beneficial or detrimental for Sirex. More work is necessary in this area to elucidate how much impact individual species interactions have on invasive species and by what mechanisms heterospecifics, parasitoids and predators are attracted to invading species.

CONSEQUENCES OF MATING SYSTEM SWITCHES ON THE EVOLUTION OF SEX-BIASED GENES IN Caenorhabditis

Authors: Cristel G. Thomas, Ian Korf, Eric S. Haag
Department or Program: MOCB
Presented by: Cristel Thomas
Abstract: Mating systems shape genome structures over the generations through their effects on population genetics and reproductive traits. In the nematode genus Caenorhabditis, some species are androdioecious (male/hermaphrodite), such as the well-studied model organism Caenorhabditis elegans, while most are gonochoristic (male/female). Furthermore, selfing species in the genus seem to lose ancestral traits related to mating. Caenorhabditis is growing to be a “model genus”, as molecular tools and genetic data become available for a number of species. It offers a unique opportunity to study the impact of changes in mating system on the evolution of genomes over a short evolutionary time period, and more specifically the evolution of genes related to sex-specific attributes. Since traits related to mating have evolved so drastically in Caenorhabditis, we expect the presence and/or the regulation of some of these genes to have varied through evolution of the Caenorhabditis species. We used deep-sequencing technology to identify genes expressed in a sex-biased fashion in a gonochoristic species, C. remanei. To shed some light on the evolutionary processes driving the evolution of mating system, we defined potential candidate genes to characterize further based on their phylogenetic distribution within the Caenorhabditis genus. We will study the function of these genes in C. remanei by combining RNA interference with assays for mating behaviour and efficiency, as well as by looking at their pattern of expression. The combined results should allow us to understand better how different mating systems evolve and impact on the evolution of mating-related genes.

Restoration of a Coastal Prairie in Maryland

Authors: Douglas E. Gill and Henry F. Sears
Department or Program: BIOL
Presented by: Douglas E Gill
Abstract: In Maryland, the two primary objectives of the Conservation Reserve Enhancement Program (CREP) are protection of water quality and provision of wildlife habitat. Native warm-season grasses (NWSG) have been used extensively in Maryland and throughout the U.S. to meet these objectives. However, typical recommended management practices for NWSG stands (i.e. disking and prescribed fire) have provided limited success in maintaining wildlife habitat. Native grasslands are systems that evolved with larger grazers, which now primarily exist in the form of domesticated livestock. We propose to evaluate the use of managed grazing for restoring and maintaining eastern grassland ecosystems, with particular focus on maintaining vegetative diversity and habit for grassland bird species. The proposed research site includes more than 200 contiguous acres that have been established in NWSGs under the CRP practice Permanent Native Grasses (CP2) for more than 10 years. Ongoing research on the site has demonstrated the benefits of the NWSG plantings, as grassland birds have appeared, nested, and flourished at the site. The grasslands have been managed for grassland birds, following Maryland CRP guidelines, to the greatest extent possible within program constraints. However, as the grasslands have matured, the use of recommended management practices has not been sufficient to maintain quality habitat, and grassland bird populations have begun to decline. Managed grazing appears to be the most ecologically sound and cost-effective method remaining to maintain plant diversity and habitat quality. We propose to evaluate the use of prescribed grazing to both restore and maintain quality grassland bird habitat, while also meeting the objective of water quality protection. Results of the study will demonstrate appropriate management protocols for using grazing as a wildlife management tool in eastern NWSG stands. It is hoped that these protocols will be incorporated into the CRP in Maryland, in some form, as either general or grazing management practices on certain types of enrollments. Results of the study will also support wildlife management efforts through other federal and state programs, as well as enhance our basic understanding of the use of grazers for wildlife management in eastern grassland ecosystems.

Post-fledging, within Hatch-Year Dispersal of Grasshopper Sparrows (Ammodramus savannarum)

Authors: Travis Anthony, Douglas E. Gill, Daniel M. Small, Jared Parks, Maren Gimpel, Jason B. Guerard, and Henry F. Sears
Department or Program: BIOL
Presented by: Travis Anthony
Abstract: Little is known about the post-fledging period in most bird species, and nothing has been reported for the family Emberizidae, including New World sparrows. We report here for the first time the sizes (wing length and body mass) of, and the distances traveled by free-flying fledgling Grasshopper Sparrows within their hatch summer within an experimentally restored Atlantic Coastal grasslands in Maryland. In the years 2002 - 2009 we recaptured 45.2% of the 823 banded nestlings (Locals) in the grasslands sometime within their hatch year. Body mass was not significantly correlated with wing length, no significant change in wing length occurred over the summers, and the average fledgling gained weight by 14% per 100 days. Smaller than average birds were missing from late summer recaptures. As expected the distance travelled increased significantly with time, but most HYs were recaptured 56m and 403m from their natal nests; the longest and fastest distance recorded was 1615 m from the natal nest in 20 days. The average time of recapture was 36 days after fledging; the longest recorded retention was 97 days from fledging. We conclude that, in this population of Grasshopper Sparrows, fledglings survive at surprisingly high rates, and that most HYs remain within the vicinity of parents and adult neighbors for most of the summer.

Temporal and spatial variation in the genetic diversity of the Hawaiian petrel (Pterodroma sandwichensis)

Authors: Andreanna J. Welch, Helen F. James, and Robert C. Fleischer
Department or Program: BEES
Presented by: Andreanna Welch
Abstract: The Hawaiian petrel (Pterodroma sandwichensis) is an endemic species that was once the dominant seabird in the Hawaiian Islands. After colonization of the Islands by humans approximately 1200-1600 years ago, and the subsequent introduction of alien mammalian predators, this species experienced a severe decline in population size. The exact timing and severity of the genetic bottleneck, however, remain unclear. A genetic analysis was conducted using nuclear and mitochondrial loci from modern, archaeological, and paleontological samples. Genetic diversity was significantly higher in ancient than in modern samples indicating that the decline in population size has impacted the genetic variability of this species. Additionally, individuals from Maui and Hawaii grouped together in a haplotype network, implying that there is some gene flow between islands. An understanding of the temporal and spatial dynamics of the genetic diversity of the Hawaiian petrel will aid in the preservation of this ecologically important endangered species.

Reproductive Asynchrony and Allee Effects in Spatial Population Models

Authors: E.A. Larsen, W.F. Fagan, C. Cosner, J.M. Calabrese
Department or Program: BIOL
Presented by: Elise Larsen
Abstract: From a population dynamics perspective, spatial mate finding problems are well studied, and decreased mate finding efficiency at low population densities is a well-recognized mechanism for the Allee effect. Temporal aspects of mate finding have been rarely considered, but reproductive asynchrony may create an Allee effect in which some females go mateless by virtue of temporal isolation. We develop and explore a model that unifies previously disparate theoretical considerations of spatial and temporal aspects of mate finding. Specifically, we develop a two-sex reaction-diffusion system to examine the interplay between reproductive asynchrony and the dispersal of individuals out of a patch. We also consider additional behavioral complications affecting mating efficiency and advective movements by males. By calculating the fraction of females expected to go mateless as a joint function of reproductive asynchrony and patch size, we find that the population-level reproductive rates necessary to offset female matelessness may be quite high. These results suggest that Allee effects caused by by reproductive asynchrony will be greatly exacerbated in spatially isolated populations.

Using Stable Isotopes to Understand Long-distance Dispersal in Migratory Birds

Authors: Clark Rushing
Department or Program: BEES
Presented by: Clark Rushing
Abstract: Long-distance dispersal (LDD) has fundamental implications for many ecological and evolutionary processes, including gene flow, population dynamics, disease spread and range expansion. Historically, our understanding of LDD has been limited by the inability of mark-recapture studies to detect these events. This limitation is especially severe for migratory birds due to the large dispersal distances exhibited by these species. Recent advances in the use of isotopes to track migratory birds have introduced another method to study dispersal. My research will use isotopes to study how winter habitat quality drives LDD in a migratory bird, the American redstart (Setophaga ruticilla). In addition, I plan to use isotopes to quantify the effects of LDD and winter habitat quality on reproductive success in this species.

Adult versus larval assemblage of Trichoptera at an urban headwater stream

Authors: Robert F. Smith & William O. Lamp
Department or Program: ENTM
Presented by: Robert Smith
Abstract: The shift from aquatic to terrestrial habitats is a key feature of aquatic insect life cycles. While watershed urbanization may impact an insect’s entire life cycle, most conservation and restoration efforts focus on in-stream habitat quality and its effect on larval stages. The terrestrial, adult stage is responsible for reproduction and colonization, and impacts to this stage may contribute to taxa loss from urban streams. We collected adult and larval Trichoptera with malaise traps at one urban and one rural headwater to assess the composition of the adult assemblage. The abundance of adults was similar between streams, but the number of species caught was lower at the urban headwater. Several species of adult caddisflies at the urban headwater were not found as larvae, indicating that although these species were potential colonizers, poor in-stream quality prevented colonization. The urban trichopteran assemblage’s low diversity also suggested that watershed urbanization may have limited migration for many taxa typically found in headwater streams. Impacts to adults and larvae that lead to the loss of populations from urban headwaters differ among species. Further study is underway to relate these patterns to life history traits of caddisfly species.

Evolution of an Adaptive Behavior in the Cavefish Astyanax mexicanus

Authors: Masato Yoshizawa, Daphne Soares, Špela Gorički, Go Ashida, and William R. Jeffery
Department or Program: BIOL
Presented by: Masato Yoshizawa
Abstract: Cavefish are faced with the challenge of finding food and mates in a completely dark environment. They are also devoid of natural predators, which may have relaxed constraints that normally prevent the emergence of behaviors that can be disadvantageous in lighted environments. Here we examine the behavioral characteristics and genetic basis of the vibration attraction behavior in Astyanax mexicanus. We define a vibration attraction behavior as the tendency of fish to move towards a vibrating probe. It is measured by (1) the time it takes a fish to initially enter a 2 cm circle around the probe, and (2) the number of times it enters the circle within a 3 minute interval. Cavefish showed significantly augmented vibration attraction behavior relative to surface fish, which is presumably adaptive for detecting water vibrations that may be a source of food and/or mates. Frequency analysis ranging from 2Hz to 800Hz and pharmacological analysis using lateral line inhibitors suggested that the lateral line system of neuromasts, which is enhanced in cavefish, is critical for vibration attraction behavior. Mating experiments between surface fish and cavefish suggested that vibration attraction behavior is inherited paternally as a polygenic trait. QTL mapping using 317 F2 offspring showed a unique genetic basis for vibration attraction behavior. There was a major epistatic interaction between QTLs on LG1 and LG5, which explained 29% of the phenotypic variance in vibration attraction behavior. To our knowledge, this is the first example of an evolved behavioral trait controlled by an epistatic interaction. We propose that the evolution of vibration attraction behavior has been instrumental for the success of Astyanax mexicanus to life in perpetual darkness.

Vocal Signatures in Pallid Bat (Antrozous pallidus) Social Calls

Authors: Bryan D. Arnold
Department or Program: BEES
Presented by: Bryan Arnold
Abstract: Contact calls are utilized by several bird and mammal species to maintain group cohesion and coordinate group movement. From a signal design perspective, contact calls typically exhibit acoustic features that make them easily localizable and encode information about individual or group identity. Pallid bats (Antrozous pallidus) are unusual among vespertilionids (the most common and diverse family of bats in temperate regions of the world) in that they often emit a loud, partially audible call several times in rapid succession while in flight. This social call appears to function as a contact call in that it is frequently given when bats return from foraging and perform circular flights before entering a crevice roost. The primary goal of this study was to examine acoustic variability of pallid bat social calls to determine the extent to which call variation could be used for roostmate recognition. To address this question, I measured digital high frequency recordings of 306 social calls collected from four sites in central Oregon. Analyses revealed that most of the acoustic variation in call structure is explained by differences among individuals, although significant differences in call structure were also detected among colonies. In addition, spectral cross correlation analysis of calls recorded from the same radio-tagged bat (N=7) on multiple evenings revealed that the frequency pattern of the social call is highly repeatable within an individual. Thus, social call structure appears to be unique to individuals, stable through time, and well-suited for maintaining social bonds among individuals at the roost site.

Local maladaptation in the aphid Macrosiphum albifrons to its host plant Lupinus lepidus var. lobbii in a primary successional landscape

Authors: Christian Che-Castaldo, Tim Hinds, John Bishop
Department or Program: BEES
Presented by: Christian Che-Castaldo
Abstract: Herbivorous insects are often locally adapted to their host plants due to direct selection by the host plant itself or indirectly by the environment in which that host plant is found. This fitness advantage can be nullified by high levels of gene flow or potentially reversed by a change in the coevolutionary arms race between plant and herbivore. While local maladaptation in insect herbivores has been found to be rare, herbivorous insects in primary successional environments may be an exception. Extinction and recolonization dynamics are common after catastrophic disturbances. In these primary successional landscapes, frequent colonization and host plant shifts by herbivores to pioneer plant species may temporarily cause local maladaptation. We examined whether the aphid Macrosiphum albifrons that feeds on Lupinus lepidus var. lobbii, the most important colonizing plant on the Mount St. Helens (MSH) primary successional Pumice Plain, was locally adapted to its host. In a greenhouse experiment, aphid adults from MSH were placed on L. lepidus from the Pumice Plain and Olympic National Park. In a field experiment, aphids from MSH and two more distant source populations, Mount Hood and Santiam Pass, were placed on L. lepidus on the Pumice Plain. Number of aphid progeny were counted after 17 days as a measure of fitness. In the greenhouse experiment, L. lepidus source population significantly affected MSH aphid fitness in terms of progeny per adult, with MSH aphids having fewer progeny on MSH plants than on plants from Olympic National Park. In the field experiment, we found a similar pattern, with aphids from MSH having significantly fewer progeny than aphids from Mount Hood and Santiam Pass when grown on MSH plants. These results suggest that aphids are locally maladapted to L. lepidus on the Pumice Plain. In an additional experiment, L. lepidus plants from the Pumice Plain were grown in the lab and fertilized with nitrogen, phosphorous (P), or not at all. MSH aphid adults were placed on these plants and progeny per adult was measured after 17 days. Aphids performed significantly better on L. lepidus that had been fertilized with P, suggesting that MSH aphids may be P-limited.

Competition between Thlaspi caerulescens and Thlaspi montanum: can phytoremediation threaten native plant populations?

Authors: Judy Che-Castaldo, David W. Inouye
Department or Program: BEES
Presented by: Judy Che-Castaldo
Abstract: Metal-hyperaccumulating plants can uptake extraordinary amounts of heavy metals into their shoots, and have been proposed for use in cleaning up metal-contaminated soils. My dissertation research examines the potential ecological risks of introducing a non-native metal accumulating plant to contaminated sites for remediation purposes. In this experiment, I tested whether phytoremediation may pose a threat to native plant populatins through interspecific competition from the hyperaccumulating plant. Thlaspi caerulescens (Brassicaceae) is a zinc- and cadmium-hyperaccumulator native to southern France, and is commonly used in phytoremediation studies. Its congener, Thlaspi montanum var montanum, is native to my study region of southwestern Colorado, where it has colonized the edges of the waste heaps, called tailings, at some abandoned silver mines. My field sites consisted of three of these mines, where I collected T. montanum seeds and soil substrate for use in the greenhouse experiment. I also examined whether soil metal content influences the competitiveness of the hyperaccumulator by using field soil collected from two locations: at the edges of the tailings and 20m from the tailings at each site. My results suggest that under certain abiotic conditions (for example, low copper levels in the substrate), T. caerulescens has the capacity to survive and reproduce more rapidly than the native T. montanum when planted on non-native soils.

The fossil record provides important new insights for the evolution of Alnus

Authors: Nathan A. Jud and Scott L. Wing
Department or Program: BEES
Presented by: Nathan Jud
Abstract: The genus Alnus consists of about 35 species of Nitrogen-fixing trees and shrubs distributed throughout the Northern Hemisphere and into montane tropical regions. The taxonomic classification of groups within Alnus has been revised numerous times based on both morphological and genetic data. Although consensus has not yet been reached on which taxonomic system is most appropriate, certain clades or subgenera are well-supported with genetic data and are consistent with traditional morphological concepts. The fossil record of Alnus leaves and reproductive structures (aments) is extensive. Alnus is unique in that the trees grow near water in habitats that accumulate sediment and are likely to preserve fossils and the durable, woody aments are typically preserved along with the leaves. This makes Alnus an important organism for study because few other genera are so well represented in the fossil record. In this study we report the oldest record of Alnus macrofossils in North America from 55.3Ma. We attribute these fossils to subgenus Alnus and discuss the subgeneric affinities of numerous younger fossil Alnus. When compared with the phylogeny, the stratigraphic record of Alnus subgenera as represented by leaves and aments can provide important insights for both morphological evolution and the establishment of the modern distributions. Our preliminary results suggest that, despite similarity with the sister genus Betula, the morphology associated with certain basal lineages is of recent origin. Additionally, the abrupt appearance of subgenus Alnus in North America during the Earliest Eocene suggests that genus originated somewhere in Asia, and that subgenus Clethropsis as well as various clades within subgenus Alnus have migrated across continents via high latitude land bridges during the globally warm Paleogene, resulting in several disjunct lineages.

Evaluating the presence of competition between native and invasive slugs in central Maryland

Authors: Megan E. Paustian and Pedro Barbosa
Department or Program: BEES
Presented by: Megan Paustian
Abstract: Although many invasive species are recognized as potential competitors of native species, the harm to the native competitor may be difficult to observe. The fitness of natives in the presence of introduced competitors should be evaluated across realistic resource levels and circumstances of interaction to suggest when competition is possible. The native slug Philomycus carolinianus is likely to compete for resources with the aggressive invasive slug Arion subfuscus in Maryland forests. In order to establish whether competition occurs between these two species, I am testing for the following criteria: 1. a decline in the fitness of P. carolinianus (adults or juveniles) in the presence of A. subfuscus and 2. evidence for competition mechanisms (resource exploitation, mucous interference, or aggression). When sharing a low-resource lab cage with either A. subfuscus or conspecifics, adult P. carolinianus experienced a similar decline in fitness, suggesting that exploitative resource competition was no greater between heterospecifics than between conspecifics. No evidence of heterospecific interference (competition independent of resource levels) was found. Adults of both species had a similar impact on juvenile P. carolinianus fitness. Given the limited support for the criteria of competition, A. subfuscus was not shown to be an immediate threat to the persistence of P. carolinianus.

Comprehensive Genetic and Morphological Analyses do not Support the Taxonomic Rank of Species for the Federally Listed Endangered Plant Agalinis acuta (Orobanchaceae)

Authors: James B. Pettengill and Maile C. Neel
Department or Program: BEES
Presented by: James Pettengill
Abstract: Agalinis acuta (Orobanchaceae) is a federally listed endangered plant species that is at risk of extinction due to habitat loss and degradation. The taxonomic status of A. acuta has been questioned based on morphological and DNA sequence similarity with A. decemloba and A. tenella. However, those species have been synonymized with A. obtusifolia. To better understand the evolutionary distinctiveness and phylogenetic affinities of these putative species and an additional congener, A. skinneriana, we sampled six chloroplast DNA loci from representatives of 35 different populations representing five putative species, characterized variation at 21 microsatellite loci across 20 populations representing A. acuta, A. decemloba, A. tenella, and A. obtusifolia, and measured 61 morphological characters assayed from multiple individuals from 18 populations. These different datasets provide evidence for five identifiable lineages that correspond to each of the five putative species. However, the magnitude and patterns of differences observed do not support the taxonomic rank of species for all taxa investigated. There is strong support for species status for both A. obtusifolia and A. skinneriana, but there is insufficient evidence to warrant the designation of species for the putative samples of the listed species A. acuta. The most appropriate taxonomic alignment is treating A. acuta and A. decemloba as one subspecies and A. tenella as another subspecies of a single species. Nomenclatural precedence dictates that the former taxon would be Agalinis decemloba ssp. decemloba and the latter would be Agalinis decemloba ssp. tenella. Whether Agalinis decemloba ssp. decemloba represents a taxon deserving of federal protection under the Endangered Species Act is also discussed.

Dynamic Echolocation Behavior in the Big Brown Bat, Eptesicus fuscus

Authors: Beatrice Mao, Dr. Murat Aytekin, Dr. Cynthia Moss
Department or Program: BEES
Presented by: Beatrice Mao
Abstract: Bat echolocation is a dynamic behavior that allows for real-time adaptations in call design in response to the particular environment in which a bat is operating (e.g. open, cluttered), or the particular task before it (e.g. orientation, foraging). Because different call designs are better suited to provide the caller with different types of information, the spectral and temporal characteristics of echolocation calls may indicate what type of information the bat seeks in a particular situation. So far, it is known that the duration and rate of emission of echolocation calls decrease and increase, respectively, as the distance between the calling bat and the object it’s ensonifying diminishes. When the big brown bat, Eptesicus fuscus, forages for insect prey, it produces frequency modulated (FM) calls, with a duration that decreases from > 5 msec during initial target approach to less than .5 msec during the final buzz before capture. The interval between successive calls also decreases as a bat flies towards its prey, from >100 ms during initial target approach to about 6 msec just before capture. Research in the lab and the field has shown that bats using FM echolocation calls adjust the duration of their calls to avoid overlap between emissions and echoes, and adjustments in call duration can be used to indicate where the bat is attending along the distance axis. We used this observation to study where in distance E. fuscus is attending when a stationary ‘distractor’ is present to produce echoes that might interfere with the bat’s ability to track a moving target. We trained bats to rest on a stationary platform and track a tethered insect that approached the bat from a starting distance of about 2 meters. In this situation, bats engaged in dynamic vocal production patterns resembling those of a free-flying bat. We went on to examine how a stationary bat adjusts its calls in response to an approaching tethered insect target in the presence of a stationary distractor, presented at two different distances and at several different angular offsets relative to the path of the tethered insect. We show that the presence of an interfering stationary target at different angular offsets and distances from the bat influences sonar vocalization parameters, which holds implications for understanding spatial information processing and perception by echolocation.

“Mum is special: socialization in Asian elephants (Elephas maximus)”

Authors: Julie Samy and Bertrand Deputte
Department or Program: BIOL
Presented by: Julie Samy
Abstract: For a young animal, the socialization process includes the development of a behavioral repertoire (all behaviors expressed or received) and the establishment of a network of conspecifics. Studies on social species and especially primates report high variability in the role played by the mother and other group members in a young animal’s social ontogeny. However, few studies have simultaneously investigated the role played by the mother and other group members in a young animal’s socialization. In species with a long social ontogeny, long gestation period, long inter-birth interval, and with one offspring per parturition, such as Asian elephants, we expect maternal investment in offspring survival and development to be important. In this study, we investigated the effect of the mother and group members on socialization by comparing the social development of 8 elephant calves with their natal group, and 6 orphans without it. We investigated the social development by measuring the repertoire richness (percentage of behaviors expressed or received at least once during the study period out of the number of possible behaviors of the total repertoire), total frequency of interactions, and diversity of interactions (interactions at a high frequency with a few classes of partners (low diversity) or at a similar frequency with a high number of conspecifics (high diversity)). The study results indicate that the repertoire richness did not differ between orphan calves and calves with their mothers. However, orphan calves had a simpler social network than calves with their mother, both when they were the initiators and when they were the recipients of interactions. Calves having their mothers in the group had a higher total frequency of interactions than orphan calves. They interacted principally with their mother but also with a higher diversity of partners compared to orphan calves. These results suggest that, in elephant society, the mother plays an important role in the socialization of its offspring by enabling the calf to interact with a variety of partners within its group.

Choosiness in rolled-leaf beetles: Leaf age and leaf configuration affect colonization by the specialist herbivore Cephaloleia fenestrata

Authors: Forde, A.J., J. E. Forsyth, M. J. McKone, J. L. Anderson, C. E. Kazanski, and M.D. Luterra.
Department or Program: BEES
Presented by: Alexander Forde
Abstract: Neotropical rolled-leaf beetles (Chrysomelidae: Hispinae: tribes Cephaloleiini and Arescini) are specialist herbivores that live and feed in immature rolled leaves of their host plants (Order Zingiberales). As a first step towards understanding the evolution of this ancient plant-insect interaction, we investigated how leaf characteristics influence the rate of colonization of Pleiostachya pruinosa (Zingiberales: Marantaceae) by its specialist rolled-leaf beetle Cephaloleia fenestrata. The leaves normally colonized by the beetles are both young (newly emerged) and in a rolled configuration. Leaf configuration is correlated with leaf age, since leaves unroll as they mature, so we used experimental manipulations to ask whether configuration and age are independently important for colonization. We manipulated the configuration of both mature and young P. pruinosa leaves so that they were either rolled tightly to a small diameter, rolled more loosely to a larger diameter, or completely unrolled. Leaves were checked after 24 hours for colonization by C. fenestrata.  Leaf configuration and leaf age both significantly influenced the probability of leaf colonization. There was essentially no colonization on mature leaves (only 1 out of 168 mature leaves were colonized), whether rolled or not. On young leaves, beetle colonization was highly dependent on leaf configuration. Rate of colonization was highest on tightly rolled leaves (50% of 82 leaves colonized), less on loosely rolled leaves (18.1% of 55 leaves), and absent on experimentally unrolled leaves (0 of 56 leaves). This pattern of colonization indicates that C. fenestrata discriminates between leaves on the basis of both leaf age and physical configuration. There are several hypotheses to explain C. fenestrata’s preference for leaves that are both tightly rolled and young, including selection on the beetles to (1) occupy enemy-free space, (2) find the highest quality food resources, and (3) optimize the ratio of time spent in leaf rolls relative to time spent dispersing.

Genome-wide Survey of Differentiation Between Hybridizing Appalachian Chickadees

Authors: Brian Davidson and Michael Braun
Department or Program: BEES
Presented by: Brian Davidson
Abstract: Hybrid zones provide valuable opportunities to study genetic, ecological, and behavioral interactions between differentiated groups, and act as natural experiments that provide information about the formation and maintenance of evolutionary diversity. Molecular methods now allow fast, economical, and genome-wide characterization of gene frequencies, which is instrumental in understanding introgression and gene flow between hybridizing populations. Black-capped and Carolina chickadees (Poecile atricapillus and P. carolinensis) hybridize along an east-west range interface through the middle of the USA and southward along the spine of the Appalachian Mountains. A previous study demonstrated long-distance bidirectional introgression at one diagnostic autosomal RFLP locus, but not at three other diagnostic loci (all sex linked or mitochondrial). Here, we used AFLP loci to characterize three parental and one introgressed population from the same area in the northern Appalachians (n= ~20 individuals per population). AFLP can generate hundreds of anonymous loci, widely spaced throughout the genome. Many of these loci are likely to be selectively neutral and able to introgress, unless there is a strong and generalized barrier to gene flow. Preliminary AFLP data were generated from ten selective-PCR primer pairs, and yielded roughly two hundred individual loci. A low proportion of loci exhibited differences between populations (~5%), and only very few were fully diagnostic. Identification of differentiated loci will enable characterization of the genomic distribution of selected and neutral regions and their potential to introgress across hybrid zones.

Phylogeography of the protistan oyster parasite Perkinsus marinus

Authors: Peter Thompson, Benjamin Rosenthal, and Matthew Hare
Department or Program: BEES
Presented by: Peter Thompson
Abstract: The protistan estuarine parasite Perkinsus marinus is found continuously along the east coast of North America from Mexico to southern parts of Canada. Previous study indicated that genetically similar populations comprise three regions: the Gulf of Mexico, the southeastern United States, and populations north of Chesapeake Bay. Here, we sampled multiple individuals from 15 locations across the parasite range in order to understand the connectivity of parasite populations within and between regions. Seven novel microsatellite loci were used to genotype P. marinus strains directly from infected oysters. Samples were analyzed using population genetic methodologies to better understand local and regional population structure. Genotypes were consistent with a diploid model with binomial superinfection probabilities. Estimates of Fst and Rst indicated that most populations were genetically distinct and did not show regional patterns as previously described. Furthermore, the genetic distance between populations did not increase with increasing geographic distance as observed in other estuarine species. Rather, cluster analysis of individual multilocus genotypes revealed a distribution of two categories of parasite lineage; endemic strains, limited to only one or two locations, and cosmopolitan strains, occupying the entire parasite range. Interestingly, certain populations were composed almost entirely of endemic strains while other populations contained only cosmopolitan strains. Taken altogether, local populations of P. marinus were highly variable and consisted of both endemic and cosmopolitan strains. We conclude that contemporary population dynamics are driven by local conditions while evolutionary gene flow is frequent enough to spread P. marinus strains among distant geographic populations.