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Shawn Meagher, Associate Professor

Parasitology, genetics, conservation biology, mammalogyshawn

Contact Information:

(309) 298-2409
Waggoner Hall 230
SA-Meagher1@wiu.edu


Degree:
 
Ph.D. - Michigan, 1995


Courses Taught: 
  • BIOL 340 (Genetics & Evolutionary Biology)
  • BIOL 425 (Conservation Biology)
  • MICR/ZOOL 460 (Parasitology)
  • LAS 501 (History & Philosophy of the Sciences)

shawn
Research Interests:

My primary research interests are in conservation genetics and wildlife disease. In particular,
I am interested in whether or not reduced genetic diversity (that is, increased homozygosity) makes hosts more susceptible to infection by parasites. This question has important conservation implications because small endangered populations inevitably become inbred, which leads to reduced heterozygosity. This could lead to higher levels of infection and the extinction of populations. I have addressed this question using a variety of approaches, focusing primarily on wild rodents and the parasitic nematodes that live in them (see Publications, below).

By performing field surveys of population variation in enzyme diversity and parasitic infection, I have found that inbred deer mouse (Peromyscus maniculatus) populations have higher frequencies of parasite infection (Meagher, 1999). I completed a large controlled experiment and found that inbreeding depresses the fitness of male house mice (Mus domesticus) to a much greater extent in competitive (“semi-natural”) conditions than could be predicted from studies in benign laboratory settings (Meagher et al. 2000). Furthermore, I have found that these same inbred males naturally acquired significantly larger pinworm infections than the other animals in the study (in prep). I am currently performing a controlled infection experiment to test whether inbred oldfield mice (Peromyscus polionotus) are more susceptible to infection with the nematode Trichinella spiralis.

In the future, I hope to apply molecular genetic approaches to examine in a more detailed fashion the correlation between genetic diversity and parasitic infection in both field populations of P. maniculatus, and my laboratory population of P. polionotus.

In addition to the particular area of genetic diversity and parasite resistance, I have a general interest in host-parasite co-evolution. I will continue to address questions concerning the physiological effects of parasites on their hosts (Meagher 1998, Meagher and O’Connor 2001, Meagher and Dudek 2002) as well as host-specificity in wild parasites.


Recent Publications:

  • Carrol, L.S., Shawn Meagher, L. Morrison, D.J. Penn, and W.K. Potts. 2004. Fitness effects of a selfish gene (the Mus t complex) are revealed in an ecological context. Evolution 58:1318-1328.


Graduate Student Research:

  • Shay Bradbury: Shay is doing a research project in "current evolution", evolutionary change that occurs over time spans short enough for humans to observe. He is using a serial passage experiment to test whether host specificity evolves in Trichinella spiralis, a nematode parasite of vertebrates. Shay is passing several generations of T. spiralis through white-footed mice (Peromyscus leucopus). If host specificity evolves, T. spiralis reproductive output will increase in P. leucopus (a new host) and decrease in rats (the host used to maintain the parasite in the lab).
  • Lori Lincoln: Lori's research is in conservation genetics. She is describing the population genetic structure of a South American monkey, the callimico (Callimico goeldii). There is some evidence that the captive population of callimicos displays "outbreeding depression", reduced reproductive output when breeding pairs are genetically distinctive. However, there is no evidence of substantial genetic differentiation among wild callimico populations. Lori has sequenced two mitochondrial DNA genes (with Jean Dubach at the Brookfield Zoo, Brookfield, IL) to determine if genetic differentiation among captive callimicos could be the cause of outbreeding depression.


Undergraduate Student Research:

  • Sumer Allensworth: Male hosts are often more susceptible than females to parasite infections. Sumer is performing an infection experiment to see if male white-footed mice (Peromyscus leucopus) are more susceptible to Trichinella spiralis, a nematode parasite of vertebrates.
  • Becky Eichenseer: Becky is studying parasite community ecology in an Illinois pond. She is using parasite surveys to determine if the fluke "yellow grub" (Clinostomum marginatum) has harmful effects on largemouth bass. She is also testing to see whether levels of parasitism differ between host sexes or ages, and whether parasitism varies by season.
  • Miranda Wire: Male hosts are often more susceptible than females to parasite infections. Miranda is performing an infection experiment to see if steroid hormone levels in white-footed mice (Peromyscus leucopus) affect resistance to Trichinella spiralis, a nematode parasite of vertebrates.