The Huck Institutes of the Life Sciences

Ecology Colloquium schedule

Upcoming talks in Ecology 590, the Graduate Colloquium
 
Schedule and Talk Summaries for Spring 2018 Ecology Graduate Colloquium (ECLGY 590)
Wednesday 12:20 – 1:10 PM, 104 Forest Resources Building

 

DATE

SPEAKER

TITLE

Jan 24

Rondy Malik

The missing link: Unraveling the role of mycorrhizal fungi in food web processes

Jan 31

Jason Kaye

Tips about how to give a seminar for students in their first colloquium

Feb 7

 

*Snow day* 

Feb 14

Joe Keller

Warming accelerates the musk thistle (Carduus nutans) life cycle

Feb 21

Ben Dillner

Plant Regeneration and Resource Availability in a Tree Tip-Up Chronosequence 

Feb 28

Lake Graboski

Characterizing species composition trajectories of forest regeneration following overstory removal in previously Quercus (oak) dominated ecosystems

Mar 7

 

Spring Break

Mar 14

Tarik Avecedo

Burkholderia sp. a bacterial endosymbiont for the squash bug pest, Anasa tristis

Mar 21

Madalyn Slook

Understanding the Consequences of Altered Light Cycles on Avian Circannual Rhythms

Mar 28

Sarah Rothman

Pollinator Habitat Restoration on Surface Mines

Apr 4

Brady Boyer

The effects of pre-dispersal seed predation on plant community diversity

Apr 18

Ted Primka

The impact of topography and its associated soil water content on tree fine root dynamics and landscape level tree root community structure

Apr 25

Benjamin Vizzachero

The Advantage of the Rare: Field Experiments on Density-Dependent Seed Dispersal by Avian Frugivores

 

 

Spring 2018 Ecology Colloquium Summaries

 

Jan. 24. Rondi Malik. The missing link: Unraveling the role of mycorrhizal fungi in food web processes

Although the food web is comprised of decomposers, primary producers and higher-level consumers, the role of mutualistic fungi remains vital to food web structure. Mycorrhizal fungi are mutualists that associate with plants and increase plant vigor through nutrient enrichment. However, it's unclear whether these mutualists vary in the degree in which they indirectly effect higher trophic links, including pathogens and herbivores. Here, I elucidate ways in which mycorrhizal composition can  impact food web connectedness. Adviser: David Eissenstat.

 

Feb. 7. Joe Keller. Warming accelerates the musk thistle (Carduus nutans) life cycle

Climate change has the potential to alter the life cycles of many plants. Warmer temperatures can advance mother plants’ phenology, causing earlier seed release and earlier germination of fall-germinating seeds. Warming can also extend the growing season later into the fall. Together these effects may cause seedlings to grow to larger sizes in their first growing season. The demography of monocarpic perennials with size-dependent flowering may be particularly sensitive to these changes, as increased growth causes individuals to reach size thresholds for reproduction more quickly. We investigated the effects of earlier seed release and warming on the life cycle of musk thistle (Carduus nutans) in a two-cohort field experiment with seven planting time treatments (ranging from planting in early August to planting in mid-November) and two temperature treatments (warmed in fiberglass open-top chambers and ambient). Earlier planting resulted in larger rosette sizes at the end of the first growing season, which lead to a larger fraction of individuals flowering as annuals. Warming also increased the growth of rosettes. Together, increased growth and larger new rosette sizes are projected to increase the local population growth rate. Adviser: Katriona Shea

 

Feb. 14. Ben Dillner. Plant Regeneration and Resource Availability in a Tree Tip-Up Chronosequence

Blow down events are a major source of disturbance in Northeastern forests. Tree tip-up creates pit and mound microsites which may receive more sunlight or have higher nutrient availability, potentially promoting regeneration of trees that fill the canopy gap. Research on the evolution of pit and mound microsites over a long time period, especially on shale bedrock sites, is lacking. This presentation will outline a proposed project that examines plant regeneration and resource availability in a tree tip-up chronosequence in the Susquehanna Shale Hills Critical Zone Observatory. The focus will be on the methods and sampling design for the project with descriptions of similar past research. Adviser: Jason Kaye

 

Feb. 28. Lake Gaboski. Characterizing species composition trajectories of forest regeneration following overstory removal in previously Quercus (oak) dominated ecosystems

Abstract coming. Adviser: Kim Steiner

 

Mar. 7. Tarik Acevedo. Burkholderia sp. a bacterial endosymbiont for the squash bug pest, Anasa tristis

The squash bug, Anasa tristis, is a devastating pest of cucurbit crops. Many true bugs possess a special organelle which houses an endosymbiont critical for the host survival. However, A. tristis has never been tested as containing any such partnerships. Here we surveyed A. tristis adults from four locations for bacterial symbionts in midgut crypts through culture-dependent methods. Ninety percent of sequences collected had high similarity to Burkholderia spp., the predominant genus of symbionts in many true bug species. Fitness assays were also performed to ascertain the importance of the prevailing Burkholderia.  The prevalence of Burkholderia within our samples suggests that A. tristis has a symbiotic relationship with Burkholderia and its absence results in costs to fitness. Adviser: Mary Ann Bruns

 

Mar. 21. Madalyn Slook. Understanding the Consequences of Altered Light Cycles on Avian Circannual Rhythms

As anthropogenic activity increases, so do disturbances to natural environmental systems. As one of the most anciently rooted daily rhythms, normal light and dark variation faces extreme alterations from urban light pollution and has the ability to disrupt typical diurnal activity patterns for the animals exposed to it. Additionally, for species that depend on seasonal changes in photoperiod to accurately time their life history events, such as avian migration, the masking of this critical cue could lead to unexamined behavioral effects. To date, studies examining the consequences that light pollution may have on migration have been overwhelmingly executed in the field, leaving much of the effect on mid-migratory behavior a mystery. Additionally, biological control mechanisms which regulate migration are still largely unknown. The purpose of this research is to alleviate these shortcomings, and to evaluate how the presence of light pollution may impact typical migratory behavior on a physiological scale. Adviser: Paul Bartell

 

Mar. 28. Sarah Rothman. Pollinator Habitat Restoration on Surface Mines

Pollinators are in severe decline, with land use change as the leading cause. Due to their extensive surface area, restoring inactive surface mines as wildflower meadows may help stabilize or reverse these population trends by increasing foraging habitat. Currently, most mining companies comply with the 1977 Surface Mining Control and Reclamation Act by seeding fast-growing, often non-native, grasses; the result is an area low in diversity and dominated by wind-pollinated species that offer little nutrition to pollinators. Cultivating wildflower meadows instead would offer a more biodiverse solution to mineland restoration and rebuild plant-pollinator networks. In undisturbed sites, recent research suggests that adding compost as a soil amendment maximizes the nutritional quality of flowers and creates preferential foraging. My research will investigate the relationship between soil quality and pollinator foraging on surface mines for the purpose of forming a recommendation for restoration. Adviser: Andy Cole

 

Apr. 4. Brady Boyer. The effects of pre-dispersal seed predation on plant community diversity

Pre-dispersal seed predation occurs whenever the seeds of a plant are killed before the fruit containing them is dispersed from the parent plant. My work is investigating if the rates of pre-dispersal seed predation differ either between plant species or differ as the abundance of a plant species changes. This data is compared to bird frugivory data collected along a latitudinal gradient. For this reason, species observed are species that are known to be frequented by birds. I hypothesize that certain predation patterns, in conjunction with the anti-apostatic behavior of birds, will lead to a stabilizing effect on the plant diversity of a community. The effects that pre-dispersal seed predation can have on a plant community have not been studied and this work can potentially add to our understanding of the trade-offs plants must make to balance defense and dispersal. Adviser: Tomás Carlo

 

Apr. 18. Ted Primka. The impact of topography and its associated soil water content on tree fine root dynamics and landscape level tree root community structure

Plants acquire nutrients and water from the soil primarily through fine roots. During this acquisition process, fine roots release a lot of carbon dioxide and become a large contributing factor to total soil respiration. Despite the importance of fine roots in these processes, little is known about how soil water content and topography impact where tree roots grow their roots across a landscape and the dynamics of this organ in a natural system. In this talk, I will cover my research proposal for my thesis and some of the preliminary data from my current study. Adviser: David Eissenstat

 

Apr. 24. Ben Vizzachero. Play-doh Ecology: Experimentally Investigating Anti-apostatic Mechanisms of Fruit Choice in Birds

Recent work in tropical forests demonstrates that fruits which are rare in a particularly place and time occupy a disproportionately high fraction of the diet of avian frugivores. If further research and experimentation in multiple environments supports this pattern, it offers a new mechanism contributing to plant species’ maintenance of hyper-diverse tropical forests, and may provide new context in understanding declining/threatened species, species invasions, and range expansions. In the past 12 months, I performed a field experiment in which I presented arrays of artificial fruit in contrast to a background of abundant real fruit. I varied the color and density of artificial fruit arrays, and measured the interest of frugivorous birds using motion-sensitive camera traps. I repeated this experiment in Argentina, Puerto Rico, and Pennsylvania. Our results indicate that in most, but not all circumstances, avian frugivores are more interested in artificial fruit which appear novel than those which resemble the dominant fruit in that environment. Our results also indicate that artificial fruit present in lower densities receive more visits-per- fruit than those present in greater densities. These results together support the hypothesis that rare fruits are more likely to be dispersed than those more common. Adviser: Tomás Carlo