Population Dynamics and Distribution by Sharon Perera
Published on: Mar 4, 2016
Transcripts - Population Dynamics and Distribution by Sharon Perera
Distribution and Population Dynamics of Tribolium castaneum Sharon M. Perera Department of Environmental Science and Policy Faculty Sponsor: Alan Hastings Ph.D. INTRODUCTION RESULTS DISCUSSION Tribolium castaneum, more commonly known as the Red On the graphs you will notice an equation for exponential decay: y=Ne^(-kx). K A fat-tailed kernel means that the final fraction ofFlour Beetle, is a model insect in the study of population longest dispersal events goes far away, potentially is the term that describes how fast the curve is descending. In our case, thedynamics. Its ability to move through a landscape landscape with 300 beetles is falling at a much faster rate (-0.373) in comparison orders of magnitude over the mean dispersalprovides invaluable insight to the movement patterns of to the 250 beetle landscape (-0.256). Viewing the graphs, it appears that both distance, whereas they would be restricted to amany other creatures. However, relatively little research graphs are falling all the way down to zero and not leveling off to any constant; few times the mean dispersal distance under ahas been done to show the shape of the distribution thus we find that the graph may be classified as a ‘thin-tail’ kernel graph. thin-tailed kernel. In a changing environment and/graphs. In this experiment we proceeded to gather or when suitable habitats are fragmented and populations follow metapopulation dynamics 250 Beetles Number of Beetlespopulation census data from the flour beetles in our (frequent local extinction/recolonization), whetherman-made landscapes. This census data is averaged and an organism can move over more than 10, 100 or 60compiled into a graph in order to extrapolate whether 1000km can strongly affect the population and 50the graph has a ‘thin-tail’ or ‘fat-tail’ kernel shape. In a 40 evolutionary dynamics of the species for at least‘thin-tail’ kernel, the graph tapers off gradually until it 30 two reasons. First, because a single organismreaches zero. The ‘fat-tail’ graph tapers off to a certain set 20 -0.2556x established in an empty site may potentially lead to y = 63.144e 10 a large population generations ahead. Second,point and then continues to maintain this set point until 0 because the longer the dispersal events, the higherit reaches the end of the landscape; unlike a ‘thin-tail’ 1 2 3 4 5 6 7 8 9 10 11 12 13 the chances that the genetic content of the Patch Numbergraph it does not taper off quite so much. This model has invasive species will be different from the recipientmany applications and is useful for population biologists population and the higher the evolutionary impact 300 Beetles of the event. Hence, long-distance dispersal events Number of Beetlesas well as wildlife conservationists who wish to track orpredict the numerical distribution of creatures in a given can contribute disproportionately to specieslandscape 120 persistence in fragmented landscapes and/or under 100 a changing environment. Reliable data on long- 80 distance dispersal are, therefore, critical to MATERIALS AND METHODS 60 realistically parameterize models predicting how 40 species may respond to a changing environment in During trial runs 200 beetles were placed in the first patch -0.3731x 20 y = 143.44e 0 terms of their population dynamics and (or holding cell) and then allowed to disperse until at least 1 2 3 4 5 6 7 8 9 10 11 12 13 microevolution one out of the two hundred fifty beetles reached the end of Patch Number the man-made landscapes. This trial gave us a time frame estimate of how long we should let the beetles disperse. It took the beetles approximately 3 and a half weeks to reach the end. Because this time frame was much too long we ACKNOWLEDGMENTS decided to add more beetles to the starting point. Our first Materials, space, equipment etc. were generation of 250 beetles dispersed for 2.5 weeks and once the beetles reached the end we censused all the beetles in the landscape and their placement within the landscape. For provided by a grant from the NSF (National Science the next generation of beetles we added 300 beetles to the Foundation). This project was done under the beginning of the landscape and followed the same protocol of guidance and expertise of Alan Hastings Ph.D. in dispersal followed by censusing. The man-made landscapes the Department of Environmental Science and we used consisted of 17 clear plastic patches (or cubes) with Policy as well as with help of my fellow 2 tablespoons of wheat flour in each patch. For each undergradute co-worker Felix Munox-Teng. generation of beetles we constructed 10 uniform landscapes. Special thanks to both of them.