Data from: Positive size-speed relationships in gametes and vegetative cells of Chlamydomonas reinhardtii; implications for the evolution of sperm.

It is commonly held that differences in gametes of the two sexes
(anisogamy) evolved from ancestors whose gametes were similar in size and
behaviour (isogamy). Underlying many hypotheses explaining anisogamy are
assumed relationships between cell size and speed in the ancestral
isogamous population. Using the isogamous alga Chlamydomonas reinhardtii,
we explored size-speed distributions in vegetative and gamete cells of ten
cell lines, and clonal data from within two cell lines. We applied an
independent speed selection approach to gamete populations of C.
reinhardtii, monitoring correlated responses in size following selection
for high speed. We demonstrate positive size-speed relationships in
clones, cell lines and artificially selected speed selection lines. We
found different size-speed relationships in the two cell types of C.
reinhardtii even though they overlap in size, suggesting that cell
composition and/or programs of gene expression are capable of altering
this relationship, and that the relationship is evolvable. The positive
genetic size-speed correlation means that the division of parent
vegetative cells into numerous gametes trades off against not only size
but also speed, a trade-off that has not received previous attention. Our
results support re-evaluating the role of speed selection in the evolution
of anisogamy.