Biomedical subjects

WE Wagner

Publications and source records attributed to WE Wagner.

3 recordsLinked to original sources

PubMed2000

The importance of calling song and courtship song in female mate choice in the variable field cricket.

Male field crickets produce calling songs, courtship songs, tactile signals and chemical signals. Although calling songs are known to play an important role in female mate choice, the importance of the other signals in mate choice is poorly understood. In the variable field cricket, Gryllus lineaticeps, females select mates, in part, based on variation in male calling song. Females prefer higher chirp rates, a trait which is partially dependent on male nutrient intake, and females prefer longer chirp durations, a trait which appears to be independent of male nutrient intake. We tested whether females also have preferences based on variation in male courtship song, and whether the structure of male courtship song varies with nutrient intake. First, we reexamined female preference for calling song chirp rate. Then, we examined: (1) female preference based on courtship song chirp rate; (2) the relative importance of calling song and courtship song chirp rate; (3) the nutrition dependence of courtship song chirp rate; and (4) the correlation between calling song and courtship song chirp rate. As reported previously, females preferred higher calling song chirp rates, and in addition, preferred higher courtship song chirp rates. Females were more likely to switch from a speaker broadcasting more attractive calling song to a speaker broadcasting less attractive calling song when the attractive calling song was associated with an unattractive courtship song than when it was associated with an attractive courtship song. Preferences based on courtship song may thus cause females to alter the choices that they made based on calling song. Males that received greater nutrients did not produce higher courtship song chirp rates. There was no correlation between calling song and courtship song chirp rate. As a result, the two traits may provide information to females about different aspects of male quality. Copyright 2000 The Association for the Study of Animal Behaviour.

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PubMed1999

Nutritional effects on male calling behaviour in the variable field cricket.

In the variable field cricket, Gryllus lineaticeps, females prefer higher chirp rates and longer chirp durations in male calling song. Higher chirp rates are energetically more expensive to produce, but the energetic cost of calling does not vary with chirp duration. We tested the hypothesis that nutrition affects male chirp rate and chirp duration. Full-sibling brothers of similar age were placed on high- and low-nutrition feeding regimes. There was no effect of feeding regime on male weight; neither group showed a significant change in weight, and the two groups did not differ from each other in weight change. However, males on the high-nutrition feeding regime both called more frequently and called at higher chirp rates when they did call. The two groups did not differ in chirp duration, the duration of pulses within chirps or chirp dominant frequency. These results suggest that females select mates based on one nutrition-dependent call character (chirp rate) and one nutrition-independent call character (chirp duration). In addition, because males in the two groups did not show significant differences in weight change, and because males on the high-nutrition feeding regime engaged in energetically more expensive calling, these results suggest that males invest any excess energy above their basic maintenance requirements in the production of call types that increase their attractiveness to females. The absence of a relationship between body condition and calling song structure for males in the field may be a consequence of this pattern of energy allocation. Copyright 1999 The Association for the Study of Animal Behaviour.

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PubMed1998

Measuring female mating preferences.

Interest in the evolution of female mating preferences has increased greatly in recent years, and numerous hypotheses have been proposed to explain how mating preferences evolve. Despite this interest, little is known about how selection acts on mating preferences in natural populations. One reason for this lack of information may be that experimental designs commonly used for testing female preferences make it difficult to quantify the preferences of individual females. Most commonly used designs share three features: they examine the preferences of populations of females, they test female responses when they are presented simultaneously with two stimuli, and they infer information on female preferences by observing female choices between alternative stimuli. Population-level choice tests, in which each female is tested only once with a set of stimuli, do not evaluate within-female variation in preference, which is necessary to document between-female variation in preference. Two-stimulus designs test only for directional preferences if female responses are tested with only a single pair of stimuli. In addition, dichotomous scoring of female responses makes detection of between-female variation in preference difficult. Simultaneous stimulus presentations can confound female preference and female sampling behaviour. An alternative method to assess female preferences is to measure repeatedly the preference functions of individual females using a single-stimulus design. The shape of a female's preference function indicates how a female's mating response varies with male trait value, and repeated measures of individual preference functions allow measurement of within- and between-female variation in preferences. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

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