TYLER, ANNA P.* and DIANE L. MARSHALL. Department of Biology, University of New Mexico, Albuquerque, NM, 87131. - Effects of elevated CO2 on male fitness in wild radish, Raphanus saitvus.
It is widely predicted that atmospheric CO2 concentrations
will double from 350 ppm to 700 ppm within the next one hundred years.
The impact of elevated CO2 on biological systems is of
considerable interest. As the amount of fixed carbon available to a
plant increases, both growth and reproduction may increase. If
increases in reproduction, and hence fitness occur and they increase
differentially among species populations or genotypes, the increases
in [CO2] may affect community structure, and/or selection
within populations. While changes in reproductive output as a result
of increased levels of CO2 have been shown in various
species, generally these studies have focused on developing seeds and
ovaries - the female half of plant reproduction; considerably less
information exists about these effects on developing pollen grains -
the male half of plant reproduction. Wild radish, Raphanus
sativus, was used as a model organism to study the effects of
elevated ambient CO2 on male reproductive success. Sibling
pairs of pollen donors were grown in growth chambers in one of two
CO2 levels, ambient (~ 360ppm) or elevated (~700ppm).
Pollen collected from these plants was used to pollinate a set of
unrelated plants. In addition to the pollinations, flowers and pollen
were collected from the donors in order to measure pollen quality and
quantity. Results will be discussed in terms of siring success,
offspring seed weight, amount of pollen produced, and pollen
germination ability.
Key words: Brassicaceae, CO2, pollen competition, pollen production, Raphanus sativus, seed paternity