The shape of female mating preferences

The “shape” of a female mating preference is the relationship between a male trait and the probability of acceptance as a mating partner. The shape of preferences is important in many models of sexual selection, mate recognition, communication, and speciation, yet it has rarely been measured precisely. Here I examine preference shape for male calling song in a bushcricket (katydid). Preferences change dramatically between races of a species, from strongly directional to broadly stabilizing (but with a net directional effect). Preference shape generally matches the distribution of the male trait. This is compatible with a coevolutionary model of signal-preference evolution, although it does not rule out an alternative model, sensory exploitation. Preference shapes are shown to be genetic in origin.

Multiple benefits of multiple mating in guppies

The rewards of promiscuity for males are undisputed. But why should a female mate promiscuously, particularly when her partners offer no resources other than sperm and increase her chances of succumbing to predation or disease? This question has been hotly debated but at present remains largely unresolved [Jennions, M. D. & Petrie, M. (2000) Biol. Rev. 75, 21–64]. One possibility is that females exploit postcopulatory mechanisms, such as sperm competition, to increase both the quality and quantity of their offspring. In this paper, we use the Trinidadian guppy, a species with a resource-free mating system, to test the hypothesis that females gain multiple benefits from multiple mating. Our results indicate that multiply mated females secure substantive advantages: They have shorter gestation times and larger broods, and they produce offspring with better developed schooling abilities and escape responses than their singly mated counterparts.

Regulation of the pAD1 sex pheromone response of Enterococcus faecalis by direct interaction between the cAD1 peptide mating signal and the negatively regulating, DNA-binding TraA protein

The Enterococcus faecalis conjugative plasmid pAD1 (60 kb) encodes a mating response to the recipient-produced peptide sex pheromone cAD1. The response involves two key plasmid-encoded regulatory proteins: TraE1, which positively regulates all or most structural genes relating to conjugation, and TraA, which binds DNA and negatively regulates expression of traE1. In vitro studies that included development of a DNA-associated protein-tag affinity chromatography technique showed that TraA (37.9 kDa) binds directly to cAD1 near its carboxyl-terminal end and, as a consequence, loses its affinity for DNA. Analyses of genetically modified TraA proteins indicated that truncations within the carboxyl-terminal 9 residues significantly affected the specificity of peptide-directed association/dissociation of DNA. The data support earlier observations that transposon insertions near the 3′ end of traA eliminated the ability of cells to respond to cAD1.

A nonspecific fatty acid within the bumblebee mating plug prevents females from remating

The best mating strategy for males differs from that of females, because females gain from mating with several males (polyandry), but males gain from monopolizing the females. As a consequence, males have evolved a variety of methods, such as the transfer of inhibitory substances from their accessory glands, to ensure exclusive paternity of the female's offspring, generally with detrimental effects on female fitness. Inhibitory substances have been identified as peptides or other specific molecules. Unfortunately, in social insects male-mating traits are investigated only poorly, although male social insects might have the same fundamental influence on female-mating behavior as found in other species. A recently developed technique for the artificial insemination of bumblebee queens allowed us to investigate which chemical compound in the mating plug of male bumblebees, Bombus terrestris L., prevents females (queens) from further mating. Surprisingly, we found that the active substance is linoleic acid, a ubiquitous and rather unspecific fatty acid. Contrary to mating plugs in other insect species, the bumblebee mating plug is highly efficient and allows the males to determine queen-mating frequencies.

Female mating preference for bold males in the guppy, Poecilia reticulata.

Although females prefer to mate with brightly colored males in numerous species, the benefits accruing to such females are virtually unknown. According to one hypothesis of sexual selection theory, if the expression of costly preferred traits in males (such as conspicuous colors) is proportional to the male's overall quality or reveals his quality, a well-developed trait should indicate good condition and/or viability for example. A female choosing such a male would therefore stand to gain direct or indirect fitness benefits, or both. Among potential phenotypic indicators of an individual's quality are the amount and brightness of its carotenoid-based colors and its boldness, as measured by its willingness to risk approaching predators without being killed. Here, we show experimentally that in the Trinidadian guppy (Poecilia reticulata) the visual conspicuousness of the color pattern of males correlates positively with boldness toward, and with escape distance from, a cichlid fish predator. Bold individuals are thus more informed about nearby predators and more likely to survive encounters with them. Mate-choice experiments showed that females prefer colorful males as mates, but prefer bolder males irrespective of their coloration when given the opportunity to observe their behavior toward a potential fish predator. By preferentially mating with colorful males, female guppies are thus choosing on average, relatively bold, and perhaps more viable, individuals. In doing so, and to the extent that viability is heritable, they potentially gain indirect fitness benefits by producing more viable offspring than otherwise.

Dimorphism and haploid fruiting in Cryptococcus neoformans: association with the alpha-mating type.

Cryptococcus neoformans is a major opportunistic fungal pathogen in AIDS and other immunosuppressed patients. We have shown that wild-type haploid C. neoformans can develop an extensive hyphal phase under appropriate conditions. Hyphae produced under these conditions are monokaryotic, possess unfused clamp connections, and develop basidia with viable basidiospores. The ability to undergo this transition is determined by the presence of the alpha-mating type locus and is independent of serotype. The association of the hyphal phase with the alpha-mating type may explain the preponderance of this mating type in the environment and the nature of the infectious propagule of C. neoformans.

Relative effects of female fecundity and male mating success on fertility selection in Drosophila pseudoobscura.

The fertility component of natural selection acting on chromosomal inversions in two experimental populations of Drosophila pseudoobscura was subdivided into the effects of female fecundity and male mating success. The offspring of the three female genotypes could be distinguished by their mitochondrial DNA haplotypes, thus permitting a direct measurement of the relative fecundities of the female genotype. The effects of male mating success on inversion frequency were measured by comparing inversion frequencies in parents and their offspring. Selection by fertility caused significant changes in inversion frequency in both populations. In one population, the changes in inversion frequency due to female fecundity and to male mating success were comparable. In the other population, however, the changes in inversion frequency due to male mating success were considerably larger than those due to female fecundity. The difference between the two populations underscores the intrinsic variability of the fertility component of fitness.

A Drosophila seminal fluid protein, Acp26Aa, stimulates egg laying in females for 1 day after mating.

Mating triggers behavioral and physiological changes in the Drosophila melanogaster female, including an elevation of egg laying. Seminal fluid molecules from the male accessory gland are responsible for initial behavioral changes, but persistence of these changes requires stored sperm. Using genetic analysis, we have identified a seminal fluid protein that is responsible for an initial elevation of egg laying. This molecule, Acp26Aa, has structural features of a prohormone and contains a region with amino acid similarity to the egg-laying hormone of Aplysia. Acp26Aa is transferred to the female during mating, where it undergoes processing. Here we report the generation and analysis of mutants, including a null, in Acp26Aa. Females mated to male flies that lack Acp26Aa lay fewer eggs than do mates of normal males. This effect is apparent only on the first day after mating. The null mutation has no other detectable physiological or behavioral effects on the male or the mated female.

High frequency of sex and equal frequencies of mating types in natural populations of the ciliate Tetrahymena thermophila.

In ciliate protists, sex involves the temporary joining of two cells of compatible mating type, followed by meiosis and exchange of gametic nuclei between conjugants. Reproduction is by asexual binary fission following conjugation. For the many ciliates with fixed multiple mating types, frequency-dependent sex-ratio theory predicts equal frequencies of mating types, if sex is common in nature. Here, we report that in natural populations of Tetrahymena thermophila sexually immature cells, indicative of recent conjugation, are found from spring through fall. In addition, the seven mating types occur in approximately equal frequencies, and these frequencies appear to be maintained by interaction between complex, multiple mat alleles and environmental conditions during conjugation. Such genotype-environment interaction determining mating type frequency is rare among ciliates.

The loss of female sex pheromone after mating in the corn earworm moth Helicoverpa zea: identification of a male pheromonostatic peptide.

Female moths often become depleted of sex pheromone after mating as the various components of virgin behavior are switched off. In examining a potential male contribution to these events in the corn earworm moth Helicoverpa zea, we have characterized a basic polypeptide from the tissues producing (accessory glands) and storing (duplex) the seminal fluids. The peptide evokes the depletion of sex pheromone when injected into virgin females. This pheromonostatic peptide (PSP) is 57 amino acids long and contains a single disulfide bridge. It is blocked at the N terminus with pyroglutamate and at the C terminus by amidation. As little as 23 ng of peptide evokes the near-complete depletion of pheromone in decapitated (neck-ligated) females that had been injected with pheromone biosynthesis-activating neuropeptide. Activity is approximately 15-fold less in intact virgins, showing that the head limits the expression of activity in these injected females. Females mated to surgically impaired males, capable of producing a spermatophore but not transferring spermatozoa or seminal fluids, are depleted of pheromone by injected peptide. Females whose abdominal nerve cords have been severed are not depleted of pheromone after mating. Thus, neural signals either descending or ascending via the nerve cord are required for the depletion of pheromone after mating. PSP, from the seminal fluids, may participate in this process by direct or indirect action on the glandular tissue; if so, it represents an unusual mechanism in insects for the regulation by seminal fluids of postmating reproductive behavior.

A book on guinea culture, covering every feature of mating, hatching, rearing, feeding, housing, marketing, cooking and serving.

Cover title: Guinea fowl.

The bantams down-to-date. A detailed description of the colors, types, standard points and weights of all the exhibition bantams; how to mate for the production of all breeds and varieties of game and "variety" bantams; inbreeding, double mating, the founding of strains and the creation of new species; housing, feeding, hatching; fitting for exhibition and general management; simplified doctoring of sick bantams.

Mode of access: Internet.

The Barber stud-mating house.

Mode of access: Internet.

Heredity and social fitness; a study of differential mating in a Pennsylvania family,

"Paper no. 32 of the Station for experimental evolution at Cold Spring Harbor, New York."

Mate choice in the brown thornbill (Acanthiza pusilla): are settlement decisions, divorce and extrapair mating complementary strategies?

In socially monogamous birds, females may express mate preferences when they first select a breeding partner, through divorce and subsequent breeding dispersal to a new partner and through extrapair mating. We examined settlement patterns, divorce and breeding dispersal in a sedentary Australian passerine, the brown thornbill (Acanthiza pusilla), in relation to two traits known to influence extrapair paternity (male age and male size). Settlement decisions, divorce and territory switching behaviour were all female strategies that reduced their likelihood of breeding with 1-year-old males. Females preferred to settle in territories with 2+ -year-old males, were more likely to divorce 1-year-old males, and only switched territories if they had an opportunity to form a new pair bond with an old male. In contrast, female settlement and divorce decisions were not influenced by male size. Female thornbills obtain a direct benefit from preferring older males as social mates because breeding success improves with male age in brown thornbills. Nevertheless, divorce rates in this species were low (14% of pair bonds were terminated by divorce), and individuals rarely switched territories following the death of a mate. Both of these mating strategies appeared to be primarily constrained by the distance adults moved to initiate a new pair bond (1-2 territories) and by the limited availability of unpaired older males in the immediate neighbourhood.