Intraspecies Size and Frequency Distribution of Rafinesquina ,Leptaena, and Sowerbyella
We have designed a research project that will test species frequency distribution among Rafinesquina ponderosa, Leptaena richmondensis, and Sowerbyella. Our null hypothesis is as there is an increase in favorable living conditions the number of species and the relative size of a species will increase. WE believe that our study of the Liberty formation will show this. We expect to find zones within the Liberty that contain more and larger species that in other parts of the formation. The formation that we are sampling is found on Indiana St. Route 1 road cut near Brookville, Indiana.
In the Ordovician Period about 450 million years ago the area of Ohio and parts of eastern Indiana were a shallow marine environment . This environment had an animal life full of brachiopods, molluscs, bryozoa, arthropods, and Echinodermata ( Schumacher, Shrake, Swinford, Brockman, Wickstrom 1987 ). Within the Ordovician period is a formation named the Liberty where our group will be basing our study on the size frequency and distribution of brachiopods : Rafinesquina, Leptaena, and Sowerbyella . to help us in our project study we have looked up a few studies pertaining to size-frequency distribution . One such study we found the comparison of the size-frequency and distribution of their subject compared to other size frequency distributions in other areas ( Golombek,Rapp 1997). The next study we found measured the density of their subjects more than the size frequency distribution ( Young, Padilla, Schneider, and Hewett 1996) . Our group plans to research and calculate the size frequency rather than the density of a species over a certain area . The last reference we will try and incorporate into our study was the idea of finding and measuring the growth rate of Rafinesquina, Leptaena, and Sowerbyella ( Cummins,Powell, Stanton, staff 1986) .
Methods
In our study we will use a random transect starting at the bottom and continuing to the highest point of the Liberty formation at the state rout 1 brookville site . We will the randomly choose 20 meter horizontal sections which will run perpendicular to the vertical transect . In these horizontal sections we will pick three sample sites and we will calculate three random sample sites along the section . The samples we will collect will be small slabs and brachiopods free from the rock . We will then us calipers to measure the width of the brachiopods. Our sampling areas will be outlined by a quarter meter square . We will then calculate our data on a computer and produce charts , tables and grafts .
Tools
Our tools for our project study will consist of A quarter meter square , calipers, string, 100 ft measuring tape .
References
Cummins,H. , Powell , E.N. , Stanton , R.J. and G. Staff. The Size-Frequency Distribution in Palaeoecology : Effects of Taphonomic Processes During Formation of Molluscan Death Assemblages in Texas Bays , Palaeontology, vol. 29 part 3,1986, pp. 495-518.
Golombek, M. and D. Rapp . Size-frequency distributions of rocks on Mars and Earth analog sites : Implications for future landed missions . Journal of Geophysical research , Feb. 25, 1997, vol 102,no. E2, pages 4117-4129.
Schumacher , G. ,Shrake, D., Swinford, E. , Brockman, C., and L. Wickstrom . Stratigraphy and Depositional Environments of the Cincinnati Group of Southwestern Ohio . Oct. 10, 1987, pp. 1-30 .
Young, B., Padilla,D., Schneider, D.,and S. Hewett. The Impotance of size-frequency relationships for predicting ecological impact of zebra mussel populations . Hydrobiologia, 1996, pp. 151-158 .
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