Department of Biological Sciences: Leading the way to Prominence
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Ron Karlson, Ph.D.

Professor

Ron Karlson, Ph.D.

Karlson

Phone: (302) 831-2794
Fax: (302) 831-2281
Email: rkarlson@udel.edu
Office: 323 Wolf Hall

Address:
Department of Biological Sciences
Wolf Hall
University of Delaware
Newark, DE 19716

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Education

  • B.A. - Pomona College
  • M.A., Ph.D. - Duke University
  • Postdoctoral - Johns Hopkins University

Research Interests

Most of my current research focuses on scale-dependent variation in the structure and dynamics of benthic communities especially those dominated by corals and other clonal invertebrates. These sessile organisms are typically very abundant and are competitively superior to non-clonal taxa. They occur on hard substrate in shallow marine environments throughout the world. Their reproductive patterns, growth forms, and settlement preferences are often directly related to their success as spatial competitors. In high-latitude coastal waters, a diverse assemblage of sponges, hydroids, bryozoans, and ascidians flourish in what are called fouling communities. Likewise in the tropics, the dominant benthic organisms on coral reefs include a rich variety of hard corals, soft corals, zoanthids, sponges, and gorgonians. Similarly, the encrusting assemblages found in cryptic environments on coral reefs are also dominated by clonal animals.

Some recent results have characterized the nature of coral communities distributed across five tropical regions along a 10,000-km stretch of the west-central Pacific Ocean. In terms of number of species, local communities tend to reflect the size of the regional species pool (referred to as regional enrichment or proportional sampling). The variation among locations within a region has been attributed to habitat differences as well as to environmental and demographic stochasticity (e.g., regional scale disturbance and recruitment processes). Thus local communities represent samples from much larger metacommunities distributed over regional scales. We have characterized these regional metacommunities in terms of species richness, species abundance distributions, and the degree of spatial aggregation among coral species (see publications listed below).

Research Group

  • Sean R. Connolly, Ph.D. - Australian Professional Fellow (ARC Centre of Excellence for Coral Reef Studies, James Cook University). Theoretical ecology, coral community ecology.
  • Terence P. Hughes, FAA, Ph.D. - Federation Fellow and Director (ARC Centre of Excellence for Coral Reef Studies, James Cook University). Coral ecology and evolution, socioeconomic and ecological resilience.
  • Richard W. Osman, Ph.D. – Senior Scientist (Smithsonian Environmental Research Center). Benthic population and community ecology.

Selected Publications

Dynamics of Coral Communities cover
  • Cornell HV, Karlson RH, Hughes TP. Local-regional species richness relationships are linear at very small to large scales in west-central Pacific corals. Coral Reefs. 2008;27(1):145–151.
  • Cornell HV, Karlson RH, Hughes TP. Scale-dependent variation in coral community similarity across sites, islands, and island groups. Ecology. 2007;88(7):1707–1715.
  • Idjadi JA, Karlson RH. Spatial arrangement of competitors influences coexistence of reef-building corals. Ecology. 2007;88(10):2449–2454.
  • Karlson RH, Cornell HV, Hughes TP. Aggregation influences coral species richness at multiple spatial scales. Ecology. 2007;88(1):170–177.
  • Idjadi JA, Edmunds PJ. The role of scleractinian corals as facilitators for other invertebrates on a Caribbean reef. Mar Ecol Prog Ser. 2006;319:117–127.
  • Idjadi JA, Lee SC, Bruno JF, Precht WF, Allen-Requa L, Edmunds PJ. Rapid phase-shift reversal on a Jamaican coral reef. Coral Reefs. 2006;25(2):209–211.
  • Karlson RH. Metapopulation dynamics and community ecology of marine systems. In: Krizer JP, Sale PF, eds. Marine Metapopulations. Academic Press; 2006.
  • Connolly SR, Hughes TP, Bellwood DR, Karlson RH. Community structure of corals and reef fishes at multiple scales. Science. 2005;309(5739):1363–1365.
  • Karlson RH, Cornell HV, Hughes TP. Coral communities are regionally enriched along an oceanic biodiversity gradient. Nature. 2004;429(6994):867–870.
  • Baird AH, Bellwood DR, Connell JH, et al. Coral reef biodiversity and conservation. Science. 2002;296(5570):1026–8; author reply 1026–8.
  • Callaghan TP, Karlson RH. Summer dormancy as a refuge from mortality in the freshwater bryozoan Plumatella emarginata. Oecologia. 2002;132(1):51–59.
  • Karlson RH. Global, regional, and local patterns in species richness and abundance of butterflyfishes: Comment. Ecology. 2002;83(2):583–585.
  • Karlson RH. Population processes in modular benthic invertebrates. In: Hughes RN, ed. Progress in Asexual Reproduction. New Delhi, India: Oxford and IBH Publishing Co. Pvt. Ltd.; 2002:255–282. Reproductive Biology of Invertebrates XI.
  • Karlson RH, Cornell HV. Species richness of coral assemblages: Detecting regional influences at local spatial scales. Ecology. 2002;83(2):452–463.
  • Cornell HV, Karlson RH. Coral species richness: ecological versus biogeographical influences. Coral Reefs. 2000;19(1):37–49.
  • Karlson RH. Dynamics of Coral Communities. Dordrecht, The Netherlands: Kluwer Academic Publishers; 1999. Population and Community Biology 23.
  • Karlson RH, Cornell HV. Scale-dependent variation in local vs. regional effects on coral species richness. Ecol Monogr. 1998;68(2):259–274.
  • Cornell HV, Karlson RH. Species richness of reef-building corals determined by local and regional processes. J Anim Ecol. 1996;65(2):233–241.
  • Karlson RH, Hughes TP, Karlson SR. Density-dependent dynamics of soft coral aggregations: The significance of clonal growth and form. Ecology. 1996;77(5):1592–1599.
  • Karlson RH, Hurd LE. Disturbance, coral-reef communities, and changing ecological paradigms. Coral Reefs. 1993;12(3-4):117–125.
  • Karlson RH, Taylor HM. Mixed dispersal strategies and clonal spreading of risk – predictions from a branching-process model. Theor Popul Biol. 1992;42(2):218–233.
  • Karlson RH. Size-dependent growth in 2 zoanthid Species – a contrast in clonal strategies. Ecology. 1988;69(4):1219–1232.
  • Karlson RH, Jackson JBC. Competitive networks and community structure – a simulation Study. Ecology. 1981;62(3):670–678.
  • Sutherland JP, Karlson RH. Development and stability of fouling community at Beaufort, North Carolina. Ecol Monogr. 1977;47(4):425–446.
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