Correlated evolution of multivariate traits: detecting co-divergence across multiple dimensions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75039/1/j.1420-9101.2007.01415.x.pd

Copulation behaviour of Glossina pallidipes (Diptera: Muscidae) outside and inside the female, with a discussion of genitalic evolution

artículo (arbitrado)--Universidad de Costa Rica. Escuela de Biología, 2007If species-specific male genitalia are courtship devices under sexual selection by cryptic female choice, then species-specific aspects of the morphology and behaviour of male genitalia should often function to stimulate the female during copulation. The morphology and behaviour of the complex, species-specific male genitalia of the tsetse fly, Glossina pallidipes Austen, were determined from both direct observations and dissections of flash-frozen copulating pairs; and we found that some male genitalic traits probably function to stimulate the female, while others function to restrain her. The male clamps the ventral surface of the female’s abdomen tightly with his powerful cerci. Clamping does not always result in intromission. Clamping bends the female’s body wall and her internal reproductive tract sharply, posteriorly and dorsally, and pinches them tightly. Males performed sustained, complex, stereotyped, rhythmic squeezing movements with his cerci that were not necessary to mechanically restrain the female and appeared instead to have a stimulatory function. Six different groups of modified setae, on and near the male’s genitalia, rub directly against particular sites on the female during squeezing. The designs of these setae correlate with the force with which they press on the female and the probable sensitivity of the female surfaces that they contact. As expected under the hypothesis that these structures are under sexual selection by female choice, several traits suspected to have stimulatory functions have diverged in G. pallidipes and its close relative, G. longipalpis. Additional male non-genitalic behaviour during copulation, redescribed more precisely than in previous publications, is also likely to have a courtship function. The elaborate copulatory courtship behaviour and male genitalia may provide the stimuli that previous studies showed induce female ovulation and resistance to remating.Universidad de Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Nonantagonistic interactions between the sexes revealed by the ecological consequences of reproductive traits

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73504/1/j.1420-9101.2004.00779.x.pd

Operational sex ratio, sexual conflict and the intensity of sexual selection.

Modern sexual selection theory indicates that reproductive costs rather than the operational sex ratio predict the intensity of sexual selection. We investigated sexual selection in the polygynandrous common lizard Lacerta vivipara. This species shows male aggression, causing high mating costs for females when adult sex ratios (ASR) are male-biased. We manipulated ASR in 12 experimental populations and quantified the intensity of sexual selection based on the relationship between reproductive success and body size. In sharp contrast to classical sexual selection theory predictions, positive directional sexual selection on male size was stronger and positive directional selection on female size weaker in female-biased populations than in male-biased populations. Thus, consistent with modern theory, directional sexual selection on male size was weaker in populations with higher female mating costs. This suggests that the costs of breeding, but not the operational sex ratio, correctly predicted the strength of sexual selection

Simultaneous age-dependent and age-independent sexual selection in the lekking black grouse (Lyrurus tetrix)

1. Individuals' reproductive success is often strongly associated with their 18 age, with typical patterns of early life reproductive improvement and late 19 life senescence. These age-related patterns are due to the inherent trade-20 offs between life history traits competing for a limited amount of resources 21 available to the organisms. In males, such trade-offs are exacerbated by the 22 resource requirements associated with the expression of costly sexual 23 2 traits, leading to dynamic changes in trait expression throughout their 24 lifespan. 25 2. Due to the age-dependency of male phenotypes, the relationship between 26 the expression of male traits and mating success can also vary with male 27 age. Hence, using longitudinal data in a lekking species with strong sexual 28 selection – the black grouse Lyrurus tetrix – we quantified the effects of 29 age, lifespan and age of first lek attendance (AFL) on male annual mating 30 success (AMS) to separate the effects of within-individual improvement 31 and senescence on AMS from selective (dis)appearance of certain 32 phenotypes. Then, we used male AMS to quantify univariate and 33 multivariate sexual selection gradients on male morphological and 34 behavioural traits with and without accounting for age and age-related 35 effects of other traits. 36 3. Male AMS increased with age and there was no significant reproductive 37 senescence. Most males never copulated and of the ones that did, the 38 majority had only one successful year. Lifespan was unrelated to AMS, but 39 early AFL tended to lead to higher AMS at ages 1 to 3. AMS was related 40 to morphological and behavioural traits when male age was ignored. 41 Accounting for age and age-specific trait effects (i.e. the interaction 42 between a trait and age) reduced the magnitude of the selection gradients 43 and revealed that behavioural traits are under consistent sexual selection, 44 while sexual selection on morphological traits is stronger in old males. 45 4. Therefore, sexual selection in black grouse operates primarily on male 46 behaviour and morphological traits may act as additional cues to 47 supplement female choice. These results demonstrate the multifaceted 48 3 influence of age on both fitness and sexual traits and highlight the 49 importance of accounting for such effects when quantifying sexual 50 selection