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Member Institutions:
Tarun Mal Department of Biological, Geological and Environmental Sciences |
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Research Interests
Exotic species capable of colonizing habitats beyond their natural ranges are thriving in an unprecedented rate as human activities are becoming more and more globalized. Often these exotic species form extensive monocultures eliminating native species from the habitats. The net result is the loss of native biodiversity. Although many exotic species are very benign in their native habitats, they become more aggressive in their adventive ranges. My laboratory is investigating how the evolution of breeding systems can lead to increased aggressiveness leading to the inordinate success of an invasive species and subsequent decline of native species.
At present, my laboratory is working on the exotic weed, Lythrum salicaria (purple loosestrife). It is an obligate outcrosser, and is handicapped, as it requires another unlike individual for successful reproduction. Yet it is a very successful invasive weed and is now a potential threat to the maintenance of diversity of North American wetland flora and fauna. We are investigating its mating system as a potential factor for its increased colonizing abilities. We are trying to address how an outcrossing invasive species overcome founder events, and how they assure reproduction when potential mates are scarce during initial colonization periods.
My laboratory is also interested in studying the impacts of invasive species on the community using field survey and manipulative experiments. We are investigating how the recipient communities adjust and change due to colonization, and how the native species interact with the invasive species. Communities are always invaded by many colonizing species, but not all are equally successful. We are trying to identify definable characters of invasive species that are potential threats to native biodiversity. Identification of such characters will allow us to identify a Keystone Invasive SpecieS (KISS) for a particular community type, and will help us manage our biodiversity more effectively.
Norms of Reaction and Phenotypic Variation in Lythrum Salicaria
T. K. Mal*, and J. Lovett-Doust**. *Dept. of BGES, Cleveland State University, Cleveland, USA, and **Dept. of Biol. Sci., Univ. of Windsor, Windsor, Canada.
We examined morphological variation of a trimorphic weed, Lythrum salicaria, in a greenhouse experiment involving cloned genotypes and four soil moisture treatments. Vegetative characters such as shoot length, shoot and root biomass and their proportional allocation did not differ among morphs; however, the length and biomass of inflorescence differed significantly among morphs. Reproductive traits such as biomass of pistil, and stamen, and length of stamen and pistil were significantly different among morphs. Soil moisture treatment also has significant influence on vegetative and reproductive traits. Norms of reaction for each genotype and morph were determined for all the traits. Although, the reaction norms of a few traits could be distinguished among morphs, those of the genotypes of a morph could not be distinguished from each other. This implies that average differences among genotypes are not consistent, and therefore may be unavailable to selection.
n.b. We are planning to start a joint research project to study Vitis vinifera. Our plans include cold resistance of local strains as compared to imported strains. The ultimate goal is to produce cold resistant V. vinifera. In addition, our plan is to study sugar metabolism and anti-oxidant production in species of Vitis.
Recent references:
- Hermann, B. P., Mal, T. K., Williams, R. J. and Dollahon, N. R. 1999. Quantitative evaluation of stigma polymorphisms in a tristylous weed, Lythrum salicaria (Lythraceae). (in press).
- Mal, T. K., Lovett Doust, J. and Lovett Doust, L. 1999. Maternal and paternal success among flower morphs in tristylous Lythrum salicaria. (in press).
- Mal, T. K. 1998. Developmental aspects of tristyly in Lythrum salicaria. Canadian Journal of Botany 76:1214-1226.
- Lovett-Doust, J., Lovett Doust, L., Biernacki, M., Mal, T. K. and Lazar, R. 1997. Organic contaminant content and plant species in the Detroit River. Canadian Journal of Fisheries and Aquatic Sciences 54: 2417-2427.
- Mal, T. K. and Lovett-Doust, J. 1997. Morph frequency and floral variation in a heterostylous colonizing weed, Lythrum salicaria. Canadian Journal of Botany 75: 1034-1045.
- Mal, T. K., Lovett-Doust, J. and Lovett-Doust, L. 1997. Time-dependent competitive displacement of Typha angustifolia by Lythrum salicaria. Oikos 79: 26-33.
- Mal, T. K., Lovett Doust, J. and Lovett Doust, L. 1997. Effect of soil moisture and fertilizer application on clonal growth and reproduction of a tristylous weed, Lythrum salicaria. Canadian Journal of Botany 75: 46-60.
- Chattopadhyay, S. P., and Mal, T. K. 1996. Angiospermic flora of Lower Long Sands Island of Sunderbans, West Bengal (India). Journal of Economic and taxonomic Botany 20: 457-489.
- Mal, T. K. 1995. Aspects of floral modification and style-morph frequency in a colonizing weed, Lythrum salicaria (purple loosestrife). In M. Munawar, T. Edsall & J. Leach (eds.), The Lake Huron Ecosystem: Ecology, Fisheries and Management. Ecovision World Monograph Series, S.P.B. Academic Publishing, The Netherlands. pp. 471-481.
- Mal, T. K., Lovett-Doust, J., Lovett-Doust, L. and Mulligan, G. A. 1992. Biology of Canadian Weeds. 100. Lythrum salicaria. Canadian Journal of Plant Sciences 72:1305-1330.
- Mal, T. K. and Subbaramaiah, K. 1991. Bisexuality in Gracilaria edulis (Gmel.) Silva (Rhodophyta, Gigartinales). Journal of Indian Botanical Society 70:405-406.
- Mal, T. K. and Subbaramaiah, K. 1990. Morphological variation in Gracilaria edulis (Gmel.) Silva in the Mandapam region, India. Proceedings of Indian Academy of Science (Plant Science) 100:383-392.
- Mal, T. K. and Subbaramaiah, K. 1990. Diurnal periodicity of carpospore shedding in Gracilaria edulis (Gmel.) Silva. Indian Journal of Marine Science 19:63-65.
- Mal, T. K. and Subbaramaiah, K. 1990. Yield and physical properties of agar in the reproductive phases of Gracilaria edulis (Gmel.) Silva occurring in the Gulf of Mannar, India. Phykos 28:256-262.
- Mal, T. K. and Subbaramaiah, K. 1990. Growth and seasonality of reproductive phases of Gracilaria edulis (Gmel.) Silva ST-1 in the Gulf of Mannar. Seaweed Research and Utilization 12:97-100.
- Chattopadhyay, S. P., Mal, T. K. and Paria, N. 1990. Notes on Hydrophylax maritima Linn. F. (Rubiaceae) from an island of Sundarbans, West Bengal (India). Advances in Plant Science 3:73-81.
- Mal, T. K., Choudhury, A. and Chatterjee, P. 1990. Eco-taxonomical studies of intertidal benthic and epiphytic algal communities of a virgin island (Prentice) in Sundarbans, India. Proceedings of the National Symposium on Marine Resources, Techniques, Evaluation and Management (Ed. A. V. Sastry) Dept. of Geology, Andhra University, Waltair, India 530 003. May 14-16, 1987. pp 29-31.
- Subbaramaiah, K., Rama Rao, K., Subba Rao, P. V., Mal, T. K., Kaliaperumal, N., Kalimuthu, S. and Ramalingam, J. R. 1988. A report on the seaweed resources off Tamil Nadu coast, India. II Sector: Alantalai-Manapad and Vembar-Nallatanni Tivu, March-April, 1988. Central Salt and Marine Chemicals Research Institute, Bhavnagar, and Central Marine Fisheries Research Institute, Cochin, India.
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