No evidence for acoustic mate-guarding in duetting buff-breasted wrens (Thryothorus leucotis)

There are few empirical tests of the acoustic mate-guarding hypothesis for the function of duetting in birds. This hypothesis states that when females are fertile, males initiate many songs or answer most of their mates solo songs to form duets and repel rival males seeking extra-pair copulations. We tested the hypothesis by comparing song initiation and answer rates of males and females in socially monogamous buff-breasted wrens (Throthorus leucotis) during pre-fertile and fertile periods. During pre-fertile periods, males often sang for short periods before being answered by their mates, yet first duets were formed earlier relative to dawn and more duets were given during the dawn chorus on pre-fertile than fertile mornings. Males initiated more songs during pre-fertile than fertile periods, whereas there was no difference between stages in female song initiation rates. The proportion of songs answered by individuals of both sexes did not differ between breeding stages. Other mate-guarding behaviours, such as frequent copulation and maintaining close proximity to mates when fertile, did not appear to be important in this species, as no copulations were observed and there was no difference in the time pairs spent in close proximity when females were fertile or not. Parentage analysis revealed that only 3% of 31 broods had young that were likely the result of extra-pair paternity. These findings do not support the acoustic mate-guarding hypothesis, and suggest that the low rate of extra-pair paternity in buff-breasted wrens was maintained without the use of acoustic or traditional paternity guards.Communicated by R. Gibson     

Migratory activity by hatchling loggerhead sea turtles (Caretta caretta L.): evidence for divergence between nesting groups

The South Florida subpopulation of loggerhead sea turtles (Caretta caretta L.) nests with great fidelity on either the southeast or the southwest coast of Florida, USA. The hatchlings that emerge from those nests must swim in opposite directions and search for different surface currents to migrate away from continental shelf waters. In this laboratory study, we compared the pattern of swimming activity shown by the hatchlings from each coast over the first 6 days of migration. Turtles from both coasts were equally active during their “frenzy” period (the first 24 h of swimming) and during the daylight hours of the 5 days that followed (the “postfrenzy” period). However, the west coast turtles were significantly more active than the east coast turtles during the nocturnal portion of the postfrenzy period. This difference may be related to the greater distance southwest coast turtles must negotiate to locate surface currents for transport out of the Gulf of Mexico and into the Atlantic Ocean basin. These differing behavioral strategies may be genetically determined, as similar correspondence between activity and distance is well known among migratory populations of birds and fish and is often based upon inherited programs of endogenously driven activity. Alternatively, behavioral differences between the two nesting groups could be a manifestation of phenotypic plasticity that arises as the hatchlings respond to unique environmental cues on each coast.     

Migratory activity by hatchling loggerhead sea turtles (Caretta caretta L.): evidence for divergence between nesting groups

The South Florida subpopulation of loggerhead sea turtles (Caretta caretta L.) nests with great fidelity on either the southeast or the southwest coast of Florida, USA. The hatchlings that emerge from those nests must swim in opposite directions and search for different surface currents to migrate away from continental shelf waters. In this laboratory study, we compared the pattern of swimming activity shown by the hatchlings from each coast over the first 6 days of migration. Turtles from both coasts were equally active during their “frenzy” period (the first 24 h of swimming) and during the daylight hours of the 5 days that followed (the “postfrenzy” period). However, the west coast turtles were significantly more active than the east coast turtles during the nocturnal portion of the postfrenzy period. This difference may be related to the greater distance southwest coast turtles must negotiate to locate surface currents for transport out of the Gulf of Mexico and into the Atlantic Ocean basin. These differing behavioral strategies may be genetically determined, as similar correspondence between activity and distance is well known among migratory populations of birds and fish and is often based upon inherited programs of endogenously driven activity. Alternatively, behavioral differences between the two nesting groups could be a manifestation of phenotypic plasticity that arises as the hatchlings respond to unique environmental cues on each coast.     

High-frequency sound transmission in natural habitats: implications for the evolution of insect acoustic communication

Summary Transmission and reception of high-frequency sound in the natural environment of bushcrickets (Tettigonia viridissima L.) was studied using the activity of an identified neuron in the insect's auditory pathway as a biological microphone. Different positions of the receiver within the habitat were simulated by systematic variation of the distance from a loudspeaker and the height above the ground. Attenuation and filtering properties of the habitat were investigated with pure-tone frequencies between 5 and 40 kHz. Sound attenuation in excess of the attenuation due to geometrical spreading alone increased with increasing frequency, distance between sender and receiver, and decreasing height within the vegetation (Figs. 2–4). The data also confirm the existence of two kinds of excess attenuation. The amount of amplitude fluctuations in the sound signals was investigated by analysing the variability of the neuronal responses at a given receiver position. Variability increased with decreasing bandwidth of a noise signal at some distance from the loadspeaker. The variability in the responses to pure tones increased with both increasing frequency and distance from the source (Fig. 7). In the selected habitat, the temporal pattern of the natural calling song of male T. viridissima was very reliably reflected in the activity of the recorded neuron up to a distance of 30 m at the top of the vegetation, and 15–20 m near ground level (Figs. 5, 8). The maximum hearing distance in response to the calling song was about 40 m. Environmental constraints on long-range acoustic communication in the habitat are discussed in relation to possible adaptations of both the signal structure and the behavior of the insects.Abbreviations excessive attenuation EA - sound pressure level SPL Offprint requests to: H. Romer     

Duetting in the subdesert mesite Monias benschi: evidence for acoustic mate defence?

Despite numerous hypotheses proposed for the function of duets, there is currently no consensus as to why males and females should coordinate their songs in such a precise way. There is evidence indicating that duets sometimes serve in territory defence, but additional functions are rarely considered. The mate-defence hypothesis proposes that birds sing in response to their partner's song and the resulting duet repels rivals and may prevent desertion of a partner. We investigated this idea in the subdesert mesite Monias benschi using playback experiments in which we broadcast recordings of solos and duets to single birds and groups. Two predictions of the hypothesis were met: (1) the solo songs of both sexes incited aggressive responses from paired birds of the same sex; and (2) compared to solo songs, pair duets elicited weaker responses from groups and duetting pairs. However, groups responded to male duets with a vigour equal to that with which they responded to male solos. This indicated that the weaker responses of groups to pair duets compared to male solos was a function of the sex rather than number of vocalising birds. Groups responded more strongly to male solos than to either female solos or pair duets, and females' responses were generally weaker than those of males. This may reflect stronger competition among males for mates, due to a male-biased sex ratio in the population. We conclude that song serves similar functions in each sex and that duets may arise through mutual mate defence.     

Vibrational communication between hitchhikers and foragers in leaf-cutting ants (Atta cephalotes)

Abstract In a foraging column of the leaf-cutting ant Atta cephalotes, minim workers (the smallest worker subcaste) hitchhike on leaf fragments carried by larger workers. It has been demonstrated that they defend leaf carriers against parasitic phorid flies. The present study examines the cues used by the potential hitchhikers to locate leaf carriers. As recently reported, foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations serve as closerange recruitment signals. We tested the hypothesis that these plant-borne stridulatory vibrations are used by the potential hitchhikers to locate workers engaged in cutting. Three different lines of evidence support this view. Firstly, the repetition rate of the stridulations produced by foraging workers increases significantly as foragers maneuver the leaf fragment into the carrying position and walk loaded to the nest. This is the moment when hitchhikers usually climb on the leaf. Although the leaf-borne stridulatory vibrations are considerably attenuated when transmitted through the workers' legs, they can nevertheless be detected at short distances by minims. This subcaste is several times more sensitive to substrate-borne vibrations than larger workers. Secondly, when a stridulating and a silent leaf were simultaneously presented at the foraging site, minim workers spent significantly more time on the stridulating than on the silent leaf. Thirdly, hitchhiking was more frequent in leaf carriers which cut fragments out of the stridulating leaf than in those cutting the silent leaf.Abstract In a foraging column of the leaf-cutting ant Atta cephalotes, minim workers (the smallest worker subcaste) hitchhike on leaf fragments carried by larger workers. It has been demonstrated that they defend leaf carriers against parasitic phorid flies. The present study examines the cues used by the potential hitchhikers to locate leaf carriers. As recently reported, foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations serve as closerange recruitment signals. We tested the hypothesis that these plant-borne stridulatory vibrations are used by the potential hitchhikers to locate workers engaged in cutting. Three different lines of evidence support this view. Firstly, the repetition rate of the stridulations produced by foraging workers increases significantly as foragers maneuver the leaf fragment into the carrying position and walk loaded to the nest. This is the moment when hitchhikers usually climb on the leaf. Although the leaf-borne stridulatory vibrations are considerably attenuated when transmitted through the workers' legs, they can nevertheless be detected at short distances by minims. This subcaste is several times more sensitive to substrate-borne vibrations than larger workers. Secondly, when a stridulating and a silent leaf were simultaneously presented at the foraging site, minim workers spent significantly more time on the stridulating than on the silent leaf. Thirdly, hitchhiking was more frequent in leaf carriers which cut fragments out of the stridulating leaf than in those cutting the silent leaf.Communicated by P. Pamilo     

Reproductive isolation with little genetic divergence between Urticina (=Tealia) felina and U. eques (Anthozoa: Actiniaria)

There has long been doubt as to whether there are one or two British species of the sea anemone genus Urticina. In the present study, populations of both putative species, which occur sympatrically in the Isle of Man, have been compared by electrophoresis of isozymes and nematocyst analysis. The analysis of fourteen isozyme loci exhibited a high genetic identity between the two taxa (I=0.907), but four loci showed significant differences in gene frequencies; thus indicating reproductive isolation. The populations displayed highly significant differences in the sizes of the various nematocyst types. The individual analysis of data for each type of nematocyst revealed that the basitrics from the actinopharynx and from the tentacles contribute most to the observed difference. Consequently, U. felina (L.) and U. eques (Gosse) are assumed to be valid species, as suggested by Manuel (1981). The mean heterozygosities for each species (0.410 and 0.436, respectively) are the highest reported for cnidarians.     

Life-history evidence for sibling species in Axiothella rubrocincta (Polychaeta: Maldanidae)

Individual Axiothella rubrocincta Johnson on the Californian coast live in U-shaped tubes, feed on the surface of the sediment, attain densities of 100 m^-2, attain lengths of 140 mm, have maximum oocyte diameters of 220 μm and produce demersal larvae. Individuals from Washington populations live in vertical tubes, feed 10–15 cm below the sediment surface, reach densities of 5000 m^-2, attain lengths of 60 mm, have maximum oocyte diameters of 385 μm and brood their young in their tubes to at least the 7-setiger stage. Individuals from California have a scalloped posterior margin of the cephalic plate, while individuals from Washington have entire margins. There are no other consistent morphological differences between populations. The population from Eagle Cove, Washington has individuals similar in size and oocyte diameter to individuals from California, but which maintain vertical tubes. A. rubrocincta represents a sibling species complex.     

Comparison between chemical and isotopic measurements of biological nitrate utilization: further evidence of low new-production levels in the equatorial Pacific

New-production (nitrate uptake) rates in the equatorial Pacific were estimated by parallel measurements of nitrate disappearance from sea water using a colorimetric method and of ¹⁵N-labelled nitrate (¹⁵NO₃ ⁻) incorporation into particulate organic nitrogen (PON) collected on GF/F filters (net nitrate uptake, conventional ¹⁵N-tracer method) and Anopore (0.2 μm) membranes. Regression analyses of 74 sample pairs gathered during 12 and 24 h productivity experiments revealed a significant positive relationship between decreasing nitrate level and ¹⁵NO₃ ⁻ accumulation into PON retained on GF/F filters, but the slopes of Model I and Model II regression lines were 1.18 and 1.29, respectively, suggesting that 15 to 22% of ¹⁵NO₃ ⁻ removed from the dissolved fraction were lost to another N-pool. Two possible avenues for the missing ¹⁵NO₃ ⁻ have been examined: uptake by submicron particles passed through the GF/F filters, and loss as dissolved organic nitrogen (DON). Nitrate uptake by small cells not recovered on GF/F filters, could be safely eliminated as a cause of loss, since ¹⁵NO₃ ⁻ uptake rates obtained from ¹⁵N entering PON collected on GF/F filters agreed well with those obtained from ¹⁵N entering PON collected on Anopore membranes (32 sample pairs). Inspection of the DON pool of 0.2 μm filtrates for excess-¹⁵N enrichment (20 samples) revealed that in nitrate-rich waters (equatorial upwelling between 1°N and 10°S), loss of ¹⁵NO₃ ⁻ as DO¹⁵N accounted for <5% of net nitrate uptake. In samples from subtropical oligotrophic waters (from 11°S southward), however, ¹⁵NO₃ loss as DO¹⁵N represented up to 20% of net NO₃ ⁻ uptake. These results, as well as experimental considerations concerning the use of colorimetric and isotopic methods to measure new production show that: (1) earlier reported high discrepancies between nitrate decreases (ΔNO₃ ⁻) and ¹⁵NO₃ ⁻ incorporation into filterable particles (ΔNO₃ ⁻/¹⁵NO₃ ⁻ incorporation >2) were probably erroneous; (2) the use of GF/F filters does not result in an underestimation of new production, although it was found to underestimate PON concentrations by up to 60%; (3) in the equatorial upwelling area (1°N to 10°S), which has high ambient nitrate levels (>2000 nmol l⁻¹) but only slight changes in concentration (0 to 80 nmol l⁻¹ d⁻¹), new production is more accurately estimated by the isotopic method than by the chemical method; (4) in subtropical oligotrophic waters (from 11°S southward) with low ambient nitrate levels (0 to 100 nmol l⁻¹), both procedures are appropriate as long as nitrate removal per incubation period is >3 nmol l⁻¹ (lower rates are only detectable with the isotopic method); (5) the traditional ¹⁵N-tracer technique does not substantially underestimate net new-production in the equatorial Pacific, and failure to account for the loss of ¹⁵NO₃ ⁻ as DON, i.e. to estimate gross nitrate uptake (gross uptake = net uptake + ¹⁵N loss) tends to underestimate new production on an average by only 10%. Overall, the apparent low level of new production in the nitrate-rich area of the central equatorial Pacific seems to be a fact, and may be ascribable to other nutrient (macro and micro) deficiencies and/or to intense in situ recycling of ammonium and nitrate (regenerated production) rather than to inaccurate nitrate uptake rates measured with the classical ¹⁵N-tracer technique. Received: 24 November 1998 / Accepted 10 March 2000     

Genetic divergence and phylogenetic inferences in five species of Mugilidae (Pisces: Perciformes)

Allozyme electrophoresis was used to compare the genetic divergence of global populations of Mugil cephalus Linnaeus, 1758 and two congeneric [M.␣curema Cuvier & Valenciennes, 1836; M. gyrans (Jordan & Gilbert, 1885)] and two more distantly related [Liza ramada (Risso, 1826); Xenomugil thoburni (Jordan & Starks, 1896)] species on the basis of 18 enzyme loci. The amount of genetic divergence among the species examined is in agreement with their present systematic status, the differences being larger among non-congeneric species than among species of the same genus. Intraspecific genetic distances in M. cephalus (average Nei's D= 0.154), although higher than those reported for conspecific populations of fish, appear to be small when compared to the interspecific values among mugilid species (0.821 ≤ Nei's D ≤ 1.744). Phylogenetic trees obtained by genetic distance methods and discrete character parsimony analysis were of similar topology, except for the relationships within the genus Mugil and for the arrangement of M. cephalus populations. Received: 7 April 1997 / Accepted: 4 February 1998     

Phylogeography of the sea star Marthasterias glacialis (Asteroidea, Echinodermata): deep genetic divergence between mitochondrial lineages in the north-western mediterranean

We explore the phylogeography of the broadcast spawner Marthasterias glacialis along south Europe and Azores. Sequences of the cytochrome c oxidase gene from 225 specimens, belonging to 10 localities, were analysed. We found 73 haplotypes grouped within two lineages (divergence 2.9%). One lineage was Atlanto–Mediterranean, whereas another one was exclusively Mediterranean. Estimation of lineages split goes back to 830,000–580,000 (±120,000) years ago. This suggests that sea-level oscillations during the Pleistocene glaciations promoted gene flow interruption, lineage divergence between basins and cryptic speciation. Secondary contact between populations allowed a recolonization of the Mediterranean by the Atlantic lineage. When animals of the Atlanto–Mediterranean lineage were considered separately, F _st index and AMOVA did not show significant differences between populations along either the Iberian Peninsula or basins. Isolation by distance between populations was not detected, and only populations of Plymouth and Azores showed significant differences to all the others. The remoteness of Azores islands might explain the structure of this population. Haphazard arrival of larvae and local extinctions rather than contemporary restricted gene flow might be responsible for the distinctive population structure of Plymouth.     

Molecular divergence between North Atlantic and Indo-West Pacific Cladophora albida (Cladophorales: Chlorophyta) isolates as indicated by DNA-DNA hybridization

Genomic relationships between North Atlantic, Australian and Japanese isolates of the benthic seaweed Cladophora albida (Huds.) Kütz. were examined in 1987 by means of DNA-DNA hybridization. The data indicate that C. albida can be divided into a North Atlantic and an Indo-West Pacific group with an intergroup hybridization response of 25 to 30% and 5.5° to 6.0°C for hybridization percentage and T _me the melting temperature reduction of hybridized sequences, respectively. This level of genome divergence is considerably higher than that observed in most other eukaryotes. The separation between the two C. albida groups presumably dates back to the closure of the Asian part of the Tethys Ocean, about 12 million years ago. The data also indicate that transatlantic C. albida populations have a greater genetic inter-relatedness than have Japanese and Australian populations. In C. albida there is no clear correlation between molecular evolution and the evolution of morphological traits. C. albida and C. rupestris (L.) Kütz have hardly any DNA sequences in common.     

Oily substances from gastral intersegmental glands of the antPachycondyla tridenta (Ponerinae): Lack of pheromone function in tandem running and antibiotic effects but further evidence for lubricative function

Summary Gas chromatographic analyses of volatizable material from gaster intersegmental complex glands ofP. tridentata revealed the presence of linoleic acid, palmitic acid, methyl oleate, and several long-chain hydrocarbons as major constituents, which form an oily fluid mixture. The nest relocation communication ofP. tridentata is tandem running. Tandem following is mediated by pheromones as demonstrated by dummy experiments with isolated gasters and thoraces and with glass balls. The secretions of all gaster complex glands, as well as hind gut contents and metapleural gland secretions, were unable to evoke tandem following. Morphology and position of the glands, lack of pheromonal function, oily properties, low volatility, and lack of antibiotic effects of these secretions strongly suggest a function as lubricants for the ants' gastral segments.     

Sneak copulations in long-tailed macaques (Macaca fascicularis): no evidence for tactical deception

Sexual competition is highly prevalent within multi-male multi-female primate groups and may lead to copulations in absence of potentially interfering bystanders. Such avoidance of bystanders may result from tactical deception or from simpler mechanisms such as taking advantage of encountered situations without bystanders, operant conditioning or a peripheral positioning of non-alpha males. We investigated which individuals are avoided as bystanders, how individuals react to the presence of bystanders and whether copulation partners separate themselves from the group in a tactical way. Our observations of a group of 15 female and seven male long-tailed macaques housed in three interconnected, but visually separated compartments revealed that both males and females can interrupt sexual behaviour and that bystanders of both sexes were avoided during copulations (n?=?256). The strength of the effect of bystanders tended to decrease with the dominance rank of male bystanders, but did not depend on the dominance rank of female bystanders. The audience effects of non-alpha individuals did not depend on the strong audience effect of the alpha male in combination with proximity with the alpha male. The effects that we found for separate bystanders suggest that sexual competition concerns rank dependent male–male competition and rank independent female–female competition. Additionally, both male and female copulation partners paid attention to the presence of bystanders and conducted fewer copulation solicitations in their presence. The timing of a male and female’s separation from the group suggests that exploitation of the peripheral position of non-alpha males, and not tactical deception, may cause these audience effects.     

Molecular evidence for multiple lineages in the gorgonian family Plexauridae (Anthozoa: Octocorallia)

Octocorals are diverse and abundant on many marine hard substrates, and, within this group, members of the family Plexauridae are an important component of tropical reef assemblages, especially in the Caribbean. To understand historical relationships within this large and diverse assemblage, and to test the monophyly of the family and some of its genera, DNA sequences of two mitochondrial loci (msh1 and ND2, ~1,185 bp) were analyzed from 46 species in 21 genera from deep and shallow waters in the tropical western Atlantic and in the tropical western and eastern Pacific (plus 9 taxa in the closely related Gorgoniidae and 1 species of the more distantly related Alcyoniidae). Five strongly supported clades were recovered. Three large clades correspond roughly to the Plexauridae, Paramuriceidae, and Gorgoniidae, and two smaller clades were comprised of taxa previously assigned to several families. Astrogorgia sp. did not group with any of the clades. The mutual relationships among the five clades remain unclear. Several genera previously regarded as unrelated appear to be grouped among the three families; e.g. Hypnogorgia sp. (Paramuriceidae) falls within a clade consisting of both Pacific and Atlantic Muricea spp. (Plexauridae), while Swiftia sp., Scleracis sp., and an Atlantic Thesea sp. (all Paramuriceidae) group with the gorgoniids. In several instances, genera containing Atlantic and Pacific species were recovered as monophyletic (Muricea spp., Bebryce spp.). However, in at least three cases (Echinomuricea spp., Thesea spp., Villogorgia spp.), placement of Atlantic and Pacific species in the same genus may reflect convergence of sclerite morphology. The results indicate a strong need for reexamination of octocoral taxonomy using a combination of molecular, morphological, and chemical evidence.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00227-005-1592-y.Communicated by J.P. Grassle, New Brunswick     

Close-range acoustic signaling and mate choice in Hawaiian crickets (Gryllidae: Laupala)

Evolution of the mate recognition system (MRS) can play a central role in animal speciation. One dramatic consequence of changes in the MRS is the failure of individuals from divergent lineages to successfully court and mate, thereby reducing gene flow between these groups. Here, we test the role of an acoustic mating signal on mate choice in a Hawaiian cricket genus (Gryllidae: Laupala). Speciation in Laupala is proceeding at an extremely rapid rate, apparently driven by divergence in aspects of the mate recognition system, most conspicuously the pulse rate of male calling song. Previous studies demonstrate that females prefer the pulse rate of a conspecific male’s song when perceived at long range, in laboratory phonotaxis trials. In this study, we examined mate choice in two species that differ dramatically in pulse rate: Laupala paranigra and Laupala kohalensis. We tested the female’s preference in both species for pulse rates at close range, by providing females an opportunity to mate with hybrid males producing a range of intermediate pulse rates. Results of our study demonstrate that while strong behavioral barriers exist between these two species, variation in the pulse rate of male calling song did not predict female mate choice at close range. These results suggest a more complex architecture to mate recognition in Laupala than previously hypothesized.     

Biochemical genetic evidence for a third species of Metridium (Coelenterata: Actiniaria)

Fine-structural analysis of the tissues of the marine demosponge Callyspongia diffusa was carried out using scanning electron microscopu and ethanol cryofracture. Micrographic data reveal the pathway of water movement through the sponge, and allow accurate measurement of the dimensions of successive structural filters in the aquiferous system. Understanding the organization and cytoarchitecture of the normal tissues of this sponge provides a basis for comparison where histopathology is being investigated, e.g. in allograft rejection reactions.     

A synomone imparting distinct sex pheromone communication channels for Choristoneura rosaceana (Harris) and Pandemis limitata (Robinson) (Lepidoptera: Tortricidae)

Summary. Male obliquebanded leafrollers, Choristoneura rosaceana (Harris), were induced to respond to a pheromone source tainted with a behavioural antagonist, Z9-tetradecenyl acetate, when a source releasing the antagonist was placed 10 cm upwind of the tainted source in a wind tunnel. However, placement of the antagonist upwind of an attractive pheromone source did not interrupt pheromone-mediated responses. Placement of a source releasing Z9-tetradecenyl acetate, a minor pheromone component of the sympatric species, the threelined leafroller, Pandemis limitata (Robinson), upwind of a calling P. limitata female, reduced conspecific male pheromone-mediated response but resulted in upwind flight by male C. rosaceana and contact with heterospecific females. Male P. limitata locked on and flew upwind to but did not contact heterospecific females when a source releasing Z9-tetradecenyl acetate was positioned upwind of a calling C. rosaceana female. In the field, adaptation or habituation to Z9-tetradecenyl acetate caused by atmospheric treatment with this compound apparently resulted in reciprocal heterospecific pheromone responses. More C. rosaceana males were captured in traps baited with their pheromone and the behavioural antagonist in small field plots treated atmospherically with Z9-tetradecenyl acetate than in nontreated control plots. Fewer male P. limitata were captured in traps baited with their own pheromone, or with C. rosaceana pheromone tainted with Z9-tetradecenyl acetate in plots treated atmospherically with Z9-tetradecenyl acetate than in nontreated control plots. We argue that Z9-tetradecenyl acetate is an important synomone which assists in partitioning the sexual chemical communication channels of C. rosaceana and P. limitata. Received 9 February 1999; accepted 22 March 1999.     

Genetic evidence for multiple parentage in eastern kingbirds (Tyrannus tyrannus)

Summary Electrophoretic analysis was performed on 28 families of eastern kingbirds (Tyrannus tyrannus) from northern Michigan to estimate the occurrence of multiple parentage. Out of 19 families used in the final analysis, at least one putative parent was excluded in 9 families, or 18 out of 60 offspring (30% of offspring). Distribution of exclusion types conforms most closely to a model of quasi-parasitism, rather than extra-pair fertilizations, with secondary females laying their eggs in the primary female's nest, but random brood parasitism cannot be ruled out as an additional or alternative source of stray genes. Based on the model of random parasitism, an estimated 39% of all offspring in this population may be unrelated to one or both of the putative parents, or 53% based on a model of quasi-parasitism. Heretofore, eastern kingbirds have been considered to be exclusively monogamous; no behavioral evidence for alternative reproductive strategies has ever been reported for this species.