Daron Blake – Effects of climate change on establishment and mortality of two invasive plant species (Mentor: Melinda Smith).
Climate change prediction models forecast increased temperatures and increased variability between rainfall events in North America. These predicted changes may have significant effects on the plant composition of the tallgrass prairie. This ecosystem, already reduced to a fraction of its original area, depends on its natural plant composition for its important role as an area of carbon sequestration. The ability of invasive plants to establish, persist, and alter the natural plant composition of this ecosystem could be drastically altered by changing climates. Two common invasive plants in the tallgrass prairie, Coronilla varia and Bromus inermis, were introduced to sixty 1-m2 plots. These plots were subjected to four treatments: delayed rainfall and ambient temperature, delayed rainfall and raised temperature, ambient rainfall and ambient temperature, and ambient rainfall and raised temperature. These climate treatments were simulated by the Rainfall Manipulation Plots (RaMPs) at Konza Prairie Biological Station. The establishment, mortality, and total number of seedlings were observed for both invasive plant species for the months of June and July. Heating treatments appeared to have minimal or no effect on any of the measured variables for either species. Precipitation treatments had no significant effect on the establishment, mortality, or total number of C. varia seedlings. Statistical analysis of the data revealed a significant difference of total B. inermis seedlings between the ambient and delayed rain regimes. B. inermis seedlings were more abundant in plots simulating ambient rainfall treatments than in delayed treatment plots. This observation contrasts with current theories which hypothesize that predicted pulses in resources may favor invasion. The observed difference in B. inermis seedling abundance may result from prolonged dry periods which may inhibit seedling success in the delayed treatment plots. An understanding of invasive plants’ responses to predicted climate change is important in predicting future changes to the already dwindling North American tallgrass prairie.

Joanna Bronkema – Testing for adaptations in color patterns of the common garter snake (Thamnophis sirtalis) along a geographic cline using phenotypic and genotypic data (Mentors: Michael Westphal and Ted Morgan).
Adaptive evolutionary processes can be tested in contemporary settings if we focus on systems that show sufficient variation at the population scale, particularly when the variation shows a regular pattern. We investigated regional variation in mtDNA and phenotypic color traits in midwestern populations of the common garter snake, Thamnophis sirtalis, in order to assess whether an observed microcline in Manitoba is the result of secondary contact between phenotypically distinct forms that share a north-south contact zone stretching from Canada to Texas. We combined phenotypic data from Kansas populations with novel genetic data and genetic data from the literature to characterize the variation. We found that a microcline also exists in Kansas in the same phenotypic and geographic direction as that in Manitoba, and that the cline in each region occurs within in separate clades that themselves are contained within one large western clade. Because the clines do not reflect mitochondrial patterns of diversification among our target populations, we conclude that some unknown large-scale adaptive process is driving the clinal variation in midwestern T. sirtalis.

Carina Castro – Temporal changes in the song dialects of Dickcissels (Spiza americana) (Mentors: Tim Parker and Brett Sandercock).
In many songbird species, individuals learn songs from each other, and as a result such species often show geographic patterns of song-type sharing, sometimes known as dialects. When young males first learn to sing, they learn from surrounding male "tutors". Despite this local learning, local dialects can still be subject to change. For instance, high population turnover due to an increase in adult immigrants could lead to introduction of foreign songs that are then learned by new recruits. High turnover could also lead to an increase in recruitment of yearlings who must learn their song. Since learning is imperfect, errors in learning, known as cultural mutations, can also alter dialects. Such temporal changes in dialects are poorly studied to the extent that even the rate of change among years is unknown in most species. We studied temporal dynamics in song dialects in the Dickcissel (Spiza americana), a species in which individuals learn songs and populations have easily recognized dialects. In previous studies, neighboring Dickcissels shared similar songs, but as distance increased between neighbors, song sharing decreased. Also, songs of individual Dickcissels remained constant throughout the breeding season. However, it is not known how Dickcissel song changes between seasons. We compared songs recorded among neighbors in 2006 to songs we recorded in 2008 at two different locations at Konza Prairie Biological Station, Kansas. Two of 9 birds banded in 2006 returned to the same areas in 2008. Despite within-season consistency in 2006, the songs of the two returning birds' changed substantially in structure between seasons. Given that result, it is less surprising that the dialect also changed on territories that had changed ownership since 2006. Song similarity between the 2006 and 2008 populations was low as measured by song type classification and assessed with the Jaccard Index of Similarity. It appears that Dickcissel dialects are dynamic over short time frames and that individual males are able to continue to learn song throughout their lifetime.

Nicholas DiRienzo – Nuptial feeding in the southern ground cricket Allonemobius socius: Conflict or investment? (Mentor: Jeremy Marshall).
In the southern ground cricket Allonemobius socius, the males provide females with a nuptial gift in the form of hemolymph. During copulation, the female chews open a specialized spur on the male’s tibia, allowing her to extract hemolymph. For females, this nuptial gift significantly increases reproductive life span and thus, lifetime fitness. For males, however, the cost of this gift can be rather significant, ranging from 0.5-8% of the male’s body mass and a significant decrease in reproductive life span. This raises an important question: Is this behavior maintained as a result of paternal investment, or rather is it a male cost for mating that is a target for sexual conflict? These opposing hypotheses set up opposite evolutionary predictions. If the behavior is a form of paternal investment, males will be selected to maintain long feeding times and there should be a positive relationship between feeding time and female measures of fitness (e.g., fecundity and offspring survival). However, if nuptial feeding is simply an upfront cost to mating for males, then males will be selected to minimize feeding time and there should not be a positive relationship between feeding time and female fitness. Here, we tested the hypothesis that feeding time is positively correlated with egg-laying in females. Specifically, virgin females were each mated with a single male. Approximately half of the females were prevented from receiving the nuptial gift. This was accomplished by covering the male’s tibial spur with liquid band-aid, which blocks the female’s access. The remaining females were not prevented from receiving the nuptial gift. Successfully mated females were allowed to lay eggs for seven days, after which the number of eggs laid was recorded. After analyzing the data we found that the females who were allowed to feed stayed in second mount (the time period in which females feed) for significantly more time than those who were not allowed to feed. Also, females who were allowed to feed laid a greater number of eggs compared to those who were not. Neither treatment showed a significant correlation between the duration of feeding and the number of eggs laid. Also, there was no difference in mating success rate or spermatophore attachment duration for either treatment. These data suggest that receiving any hemolymph during feeding, rather than the quantity received, increases the rate of egg-laying in females. This result can be explained by one of three, non-mutually exclusive, possibilities: (1) any hemolymph is a significant gift, (2) hemolymph provides additional cues to the female to lay more eggs, or (3) the hemolymph contains an egg-dumping protein by which males manipulate females to lay more eggs. Regardless of the explanation, it is clear that longer feeding times, while beneficial to females, do not enhance this component of male fitness. In all, nuptial feeding appears to be a target of sexual conflict.

Jennifer Fill – The influence of habitat variation on snake body temperature and behavior at Konza Prairie (Mentor: Page Klug and Kimberly With).
Snakes are important members of the threatened tallgrass prairie ecosystem, not only for their own intrinsic value but also as predators of grassland bird nests. An understanding of how snake behavior is influenced by tallgrass prairie management (burning and grazing) is critical in understanding how they will respond to the anthropogenic changes to the ecosystem and how this may affect their predatory relationship with grassland birds. In order to understand how snakes are impacted by various management regimes it is crucial to look at the basic relationships between snake body temperature and habitat. Since snakes are ectotherms, their body temperature is critically dependent on the thermal properties of their environment, and body temperature has a profound influence on their physiology, fitness, and behavior. My objective was to investigate the influence of burning and grazing on snake behavior. To do this I looked at the relationship between snake body temperature and habitat structure resulting from experimental grazing and burning treatments on Konza Prairie. I radio-tracked yellow-bellied racers (Coluber constrictor) and Great Plains ratsnakes (Pantherophis emoryi) on Konza Prairie from June to August, recording body temperature and both watershed (treatment type) and habitat at each location. ANOVA results showed that body temperature differed significantly between species and within each species it differed among snakes located in grassland, edge, forest, and shrubby draws. Contrary to the expectation that racers would be found most often in grassland and least in draws, and that ratsnakes would be found more often in edge than in grassland (areas in which body temperature most closely matched the preferred temperature of the species), I found racers using shrubby draws more often in less frequently burned areas while ratsnakes exhibited no outstanding trend. Based on the correlation between body and litter temperatures in the racer and between body and under-rock temperatures in the ratsnake, I conclude that behavioral use of habitat in the racer is more strongly affected by management due to alteration of substrate by burning. Average body temperature of the racer varied significantly among individual watersheds, and the lack of a difference in body temperature among macrohabitats within each watershed would suggest the influence of management treatment. Differences in use of macrohabitats may also be a result of foraging strategy, availability of macrohabitat, or predator avoidance. While the direct effects of this behavioral change on snake fitness due to management are uncertain, it represents a reaction to alteration of the landscape that may have important implications for biodiversity conservation.

Laura Kangas – Spatial and temporal physiological variation among tallgrass prairie plants (Mentor: Jesse Nippert).
Landscape-level relationships of plant productivity and composition in response to the dominant influences of fire, grazing, and drought in the tallgrass prairie have been well documented. However, less is known about the relationships at a smaller scale within the same area. The objective of this study was to characterize the physiological variability along a topographic gradient at community and individual levels and identify drivers of this variation. We measured leaf area index by plot and stomatal densities, leaf-level physiological characteristics, predawn and midday water potentials, and canopy height for each species in ten plots along a topographic gradient. Environmental data was logged by sensors near each plot. Leaf area index was similar across the topographic gradient in June, and differentiated as the summer progressed, becoming greatest in the lowland (LAI = 4.6) and least in the upland (3.4). Above-average rainfall during the growing season resulted in minimal water stress, even in the uplands. Stomatal density, determined for Andropogon gerardii and Sorghastrum nutans, was not significantly correlated with conductance rate, however, the stomatal densities of both species showed decreasing trends along the topographic gradient. For the C4 grasses, photosynthesis (A), conductance (gs), and transpiration (E) were highest in the beginning of the summer and declined over June and July, while gas exchange rates for C3 forbs and grasses varied considerably between sampling dates. Multivariate analyses of environmental factors indicated that A, gs, and E in C4 grasses were related to relative humidity and soil temperature. As a group, there was no significant relationship between abiotic factors and gas exchange rates for C3 species, with the exception of Dichanthelium oligosanthes and Ambrosia psilostachya. With these exceptions, these results are consistent with previous studies of the positive response of C4 plants in relation to abiotic conditions, while C3 forbs and grasses indicate no response; and rather are influenced by biotic interactions, related to that of grass productivity (Briggs and Knapp 2001). The above-average rainfall during the growing season provided interesting implications for this study, as both C4 and C3 species had high rates of leaf-level gas exchange. However, even when water did not limit growth, the community and individual-level variability measured along the topographic gradient indicated microsite complexity with varying environmental drivers between the C4 and C3 species present.

Jorge Mendoza – Investigating the home-ranges of Common Nighthawks (Chordeiles minor) (Mentors: Rebecca Lohnes and Brett Sandercock).
Limited studies have been conducted with Common Nighthawks (Chordeiles minor) and much of their natural history remains unknown. One questions is whether nighthawks maintain territories or home ranges. Previous studies based on observations of unmarked birds in urban areas have concluded that nighthawks are territorial. In order to study the home range of Common Nighthawks at Konza Prairie we used radio telemetry (a more precise and unbiased method). We captured six male Common Nighthawks by spotlighting at night at Konza Prairie. All birds were weighed, measured (wings, tarsus, total head), and blood was collected. To each bird, we attached a backpack radio transmitter with a necklace and thorax harness. Two of the six nighthawks with radio dispersed from Konza Prairie and one radio was dropped with a week of attachment. Movements recorded during the summer indicated that male nighthawks maintain large home ranges ranging from 1 to 3 km2 in area, and birds used different locations depending the time of day (morning, afternoon, evening and at night). Our movement data also showed some overlapping in the evening at the point where nighthawks showed the most flying activity. We did not observe any form of territoriality and it should be studied better in the future. Our results showed that radio telemetry can be successful with nighthawks and it could be useful to monitor their activity in order to investigate questions regarding their mating system and breeding behavior.

Amy Strauss – Effects of habitat on geographic patterns of song sharing in Dickcissels (Spiza americana) (Mentor: Tim Parker).
Dickcissels (Spiza americana) are oscine songbirds in which males use song in territorial defense and possibly to attract females. Males learn their song by imitating nearby territories, and this creates localized geographic patterns of song sharing, sometimes known as ‘dialects’. Various factors are hypothesized to influence the creation of these dialects, including the rate of learning errors ('cultural mutations'), immigration and emigration between populations (rate of territory turnover), proximity of each individual to neighboring territories, and the ability of sound to travel across a particular distance. These factors are presumably impacted by the conditions and quality of the habitat in which the birds live and breed. We investigated whether or not varied habitats showed differential patterns of song similarity between adjacent male Dickcissels by recording the songs of neighboring Dickcissels along continuous road transects, and noting the proportion of different habitats along those transects. Songs were then analyzed by comparing spectrograms, and classified into categories based on similarity. There was no significant correlation between general habitat cover and average Dickcissel density or between general habitat cover and average song similarity between adjacent birds (Jaccard Index of Similarity). We did find that average song similarity between adjacent birds increased as a function of declines in the average Dickcissel density per transect. This result could be explained by the fact that Dickcissel density on transects was unrelated to the density of recorded birds, which indicates that transects with higher Dickcissel density presumably had a higher number of unrecorded birds between adjacent recorded birds. More sophisticated analyses will be necessary to determine how song similarity changes over increasing distances between two birds, how variance in habitat and Dickcissel density may be related to patterns of song sharing, and how more specific designations of various habitats impact song sharing to ultimately understand the link between patterns of geographic song sharing and ecological factors.

Katie White – Evaluating fish habitat usage in the Kansas River at species and community levels (Mentors: Craig Paukert and Joe Gerken).
In large river systems, little is understood about the influence of different habitat types on species and community-level characteristics of fish. This study had two goals: 1) to assess differences in fish species and community attributes between three habitat types (mud bank, log jam, rip rap) at 439 randomly selected sites within the main channel along the entire Kansas River, and 2) to investigate fish utilization of two flooded secondary channels in a river reach located near Manhattan, Kansas. Daytime low pulse electrofishing during May-August 2006 and 2007 yielded 1468 total fish dominated by five taxa (flathead catfish Pylodictis olivaris, red shiner Cyprinella lutrensis, river carpsucker Carpiodes carpio, freshwater drum Aplodinotus grunniens, and blue sucker Cycleptus elongatus) from the three habitat types in the main channel along the entire river. Standardized seine hauls with a 4 meter seine net yielded 1288 fish from 6 samples taken within the main channel, dominated by four taxa (red shiner, white bass Morone chrysops, freshwater drum, and gizzard shad Dorosoma cepedianum), and 584 fish from five samples taken within the secondary channels, dominated by three taxa (red shiner, sand shiner Notropis stramineus, freshwater drum). Species richness and diversity were significantly highest in rip rap, and four species (shovelnose sturgeon Scaphirhynchus platorynchus, flathead catfish, blue sucker, smallmouth buffalo Ictiobus bubalus) had significantly higher abundances in one of the three habitat types. Discriminant function analysis and percent similarity indices indicated that fish assemblages did not differ among the three habitat types in the main channel or between secondary and main channels. The Kansas River fish community is dominated by habitat generalists and tolerant species that can exploit various habitats, potentially leading to a lack of community-level habitat associations. This pattern could also result from temporal effects (little habitat partitioning in the summer season), or unnoticed association patterns (habitat selection by specific fish life stages). Future research should focus on the mechanisms of how fish are utilizing different habitat types in the river and should ideally sample throughout the year and across age classes to assess any temporal or ontological trends in habitat associations.

Last updated: August 2008