▪ Abstract Extra-pair paternity (EPP) is extremely variable among species of birds, both in its
frequency and in the behavioral events that produce it. A flood of field studies and …

Research conducted in the last fifteen years has placed in question many of the traditional
conclusions scholars have formed about human female sexuality. Though conventional …

Because populations of territorial birds are relatively stable compared to those of other
animal taxa, they are often considered to be tightly regulated. However, the mechanisms that …

Socially monogamous species vary widely in the frequency of extrapair offspring, but this is
usually discussed assuming that females are free to express mate choice. Using game …

Males of many species can breed in distinct alternative phenotypes; for example, in many
birds some males breed in dull plumage while others breed in bright plumage. Because …

Highlights•Male fruit flies use aggression for resource defence polygyny.•We tested for
additional adaptive functions of aggression in male fruit flies.•We found that males used …

Simultaneous effects of mate guarding on a male's energy intake and expenditure have not
been measured. We tested whether guarding males of the western Mexican whiptail lizard …

Sperm competition is the competition between the sperm of two or more males to fertilize the
ova of a single female. Over the past few decades, the extent to which sperm competition …

In many birds, males are presumed to protect their paternity by closely guarding their mate
or copulating frequently with her. Both these costly behaviors are assumed to reduce the risk …

Polygyny and extra-pair paternity are generally thought to enhance sexual selection.
However, the extent to which these phenomena increase variance in male reproductive …