Females frequently mate with several males, whose sperm then compete to fertilize
available ova. Sperm competition represents a potent selective force that is expected to …

The spermatozoon is a highly differentiated and polarized cell, with two main structures: the
head, containing a haploid nucleus and the acrosomal exocytotic granule, and the flagellum …

The deer mouse (genus Peromyscus) is the most abundant mammal in North America, and it
occupies almost every type of terrestrial habitat. It is not surprising therefore that the natural …

From flocking birds to swarming insects, interactions of organisms large and small lead to
the emergence of collective dynamics. Here, we report striking collective swimming of …

Sperm storage, the extended maintenance of viable sperm, probably occurs in most
internally fertilizing animals. Because it temporally separates mating from conception, sperm …

The functions of the female reproductive tract not only encompass sperm migration, storage,
and fertilization, but also support the transport and development of the fertilized egg through …

While only a single sperm may fertilize the egg, getting to the egg can be facilitated, and
possibly enhanced, by sperm group dynamics. Examples range from the trains formed by …

Kin discrimination, the differential treatment of conspecifics based on kinship, occurs across
the tree of life, from animals to plants to fungi to bacteria. When kin and nonkin interact, the …

In species where females mate promiscuously, competition between ejaculates from
different males to fertilize the ova is an important selective force sha** many aspects of …

Cooperation between cells is a widespread phenomenon in nature, found across diverse
systems ranging from microbial populations to multicellular organisms. For cooperation to …