Taylor, David , Bilyeu, Jade .
Evolution of pollen size in angiosperms clades.
Recent analyses have shown that pollen largest dimension varies significantly between major angiosperm clades. They show the monocot clade has a significantly larger maximum average size than eudicots. Our hypothesis is that there can be significant difference in the largest pollen dimension when comparing the average largest pollen dimension of one clade or order to another. We did order by order and larger clade comparisons using a data base containing data for largest pollen dimensions for all angiosperms from Erdtman, 1971, the largest summary of angiosperm pollen at the family level. These data are mostly from light microscopy, but the techniques of processing are fairly uniform, so results should be consistent. Unfortunately, Erdtman did not give averages,rather the range of the largest dimension. Thus his data were adjusted in two ways. First, the conscriptions of the families were updated to reflect the work of the angiosperm working group as reflect in Angiosperm website (http://www.mobot.org/mobot/research/apweb/). Where the families had new conscriptions, Erdtman's species were reassigned and these data were adjusted. Finally, because Erdtman's data only have the range of the largest pollen dimension, two data points were collected for each family, the maximum largest dimension and the minimum largest dimension for each family and statistics comparisons made on the averages of each. These data sets were checked for normal distribution.The mean, median and mode of each data set were compared using the Microsoft Excel program to determine normality. Because of the lack of normalcy, all data sets were then transformed using the log10 in Microsoft Excel to establish normalcy. The IBM SPSS program was used to compare among the transformed data sets. A one way ANOVA was conducted to compare the means of the data and detect any significant differences. Descriptive statistics and the Levene's test(homogeneity of variances) were run. If the null hypothesis for the Levene's statistic failed to be rejected then a Tukey test was done to compare the specific groups. Our preliminary analysis shows that most clades and orders do not vary significantly, but order to order variation is found, such as the Alismatales have significantly larger minimum and maximum average pollen dimensions than other monocots, the Malvales have significantly larger maximum average pollen dimension than Brassicales within the rosids, and Dipsacales have significantly larger minimum and maximum average pollen dimensions than Asterales within the asterids. Multiple ecological factors may explain this variation.
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1 - INDIANA UNIVERSITY SOUTHEAST, Department Of Biology, 4201 GRANT LINE ROAD, NEW ALBANY, IN, 47150, USA
2 - INDIANA UNIVERSITY SOUTHEAST, Biology, 4201 Grant Line Rd, New Albany, IN, 47150, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Wednesday, July 11th, 2012
Time: 1:45 PM