Ecologists and evolutionary biologists have been interested in the functional biology
of pollen since the discovery in the 1800s that pollen grains encompass tiny plants
(male gametophytes) that develop and produce sperm cells. After the discovery of double
fertilization in flowering plants, botanists in the early 1900s were quick to explore
the effects of temperature and maternal nutrients on pollen performance, while evolutionary
biologists began studying the nature of haploid selection and pollen competition.
A series of technical and theoretic developments have subsequently, but usually separately,
expanded our knowledge of the nature of pollen performance and how it evolves. Today,
there is a tremendous diversity of interests that touch on pollen performance, ranging
from the ecological setting on the stigma, structural and physiological aspects of
pollen germination and tube growth, the form of pollen competition and its role in
sexual selection in plants, virus transmission, mating system evolution, and inbreeding
depression. Given the explosion of technical knowledge of pollen cell biology, computer
modeling, and new methods to deal with diversity in a phylogenetic context, we are
now more than ever poised for a new era of research that includes complex functional
traits that limit or enhance the evolution of these deceptively simple organisms.