Behavioural fever and chills

In mammals and other endotherms, parasitic infection is often associated with an endogenous fever response, in which the host's body temperature is increased above the norm by several degrees. It is usually argued that this is an adaptive response that helps the body to fight infection by stimulating natural defence mechanisms, though the issue remains controversial (Kluger et al., 1998). Whilst it is true that under many circumstances the body's elevated temperature can help fight off an...

Experimental Studies of Condition Dependence in Insect Sexual Traits

We surveyed the published literature of experiments using controlled variation of environmental or genetic factors to investigate condition-dependent expression of sexual traits in insects. Johnstone (1995) was used to obtain references for literature published prior to 1995, and we searched an electronic database (Web of Science http wos.mimas.ac.uk) for relevant recent articles. We also consulted the reference lists of these papers to identify additional studies. Although not exhaustive, the...

Sperm number

Theory predicts that an increased number of sperm is advantageous in sperm competition, either because a larger ejaculate volume displaces more rival sperm or due to numerical superiority. In general, sperm competition favouring numerous sperm may have led to the evolution of many tiny sperm and may even be responsible for the evolution of the two sexes (Parker et al., 1972 Bulmer and Parker, 2002). Comparative data in numerous animal groups have corroborated this finding. Males invest more...

References

Alcock, J. (1994) Post-insemination associations between males and females in insects the mate-guarding hypothesis. Annual Review of Entomology 39, 1-21. Andersson, J., Borg-Karlson, A.-K. and Wiklund, C. (2000) Sexual cooperation and conflict in butterflies a male-transferred anti-aphrodisiac reduces harassment of recently mated females. Proceedings of the Royal Society of London, Series B 267, 1271-1275. Andersson, J., Borg-Karlson, A.-K. and Wiklund, C. (2003) Antiaphrodisiacs in pierid...

Densitydependent prophylaxis

Most pest species of insects, almost by definition, exhibit wide fluctuations in population density from one generation to the next when conditions are favourable, population densities are high, and when they are less favourable they are low. For example, population densities of the larch budmoth (Zeiraphera diniana), a lepidopteran forest pest, may vary by more than 20,000fold over five generations (Speight et al., 1999). Low- and high-density environments differ in a number of qualitative and...

The Hoverfly Mimics 51 Resemblance

Hoverfly colour patterns have often been labelled as mimetic, but only some species resemble their models closely, whereas others resemble their supposed models only vaguely, so are at best rather poor mimics see, for example, the assessments in Howarth et al., 2000 . There is a clear distinction in the literature between bumblebee mimics, which are usually accepted as such without question, and honeybee and wasp mimics, where a large proportion are generalized or imperfect to the human eye....