Subordinate males are more likely to help if unrelated to the breeding female in cooperatively breeding white-browed scrubwrens

Subordinates in communally breeding groups of birds usually help to provision nestlings, but in some species helping-at-the-nest is facultative. In species in which groups usually contain relatives, subordinates either always feed young or are more likely to do so when breeding dominants are close relatives, suggesting that benefits of helping collateral kin are important. In other species, adult group members are unrelated to each other and males may only feed young if they have gained paternity, showing that cooperation is related to the mating system. The white-browed scrubwren, Sericornis frontalis, is a communally breeding species in which most groups consist of a simple pair or a dominant pair with a subordinate male. Subordinate males either fed nestlings in a given nest at a rate comparable to the dominants, or did not feed them at all. Breeding groups usually formed through natal philopatry of males, so that about 80% of subordinates were closely related to one or both members of the dominant pair. However, because of death and dispersal, 54% of subordinates were unrelated to the resident female. Although subordinates with their mother fed nestlings in 48% of cases, they fed offspring in 75% of cases if their mother had been replaced by an unrelated female, suggesting that their decision to help is influenced by the opportunity to mate with the female. Supporting this conclusion, relatedness to the dominant male did not affect subordinate behaviour, and genetic studies showed that subordinates often gained paternity if unrelated to the female. Thus, paradoxically, provisioning nestlings is related to the opportunity for mating in a society in which there is natal philopatry and subordinates are usually related to one or both members of the dominant pair. Received: 25 January 1997 / Accepted after revision: 1 May 1997     

An experimental examination of female preference patterns for components of the male advertisement call in the quacking frog,<Emphasis Type="Italic"> Crinia georgiana</Emphasis>

Even though females prefer particular components of a male display, their preferences may not be expressed during mate choice. Here, we quantified female preference patterns in the frog Crinia georgiana for call rate, pulse number and dominant frequency using two-speaker trials. Females typically chose signals emitted at a higher rate, with more pulses (when variation was extreme) and with an average dominant frequency. The results for pulse number and call rate agree with a previous field study which found that these two call components explained significant variation in male mating success. In contrast, the strong preferences for average dominant frequencies detected here disagree with the previous field study which failed to find any relationship between dominant frequency and male mating success. To explain the discrepancy we investigated whether the patterns of female preference for dominant frequency changed when another property, call rate, was varied simultaneously. Most females chose the call with an average dominant frequency when offered a choice between a call with an average dominant frequency and call rate or a non-average dominant frequency (±2 SD) and high call rate. When the differences in dominant frequency were reduced (±1 SD), females showed no clear preference for either signal. Accordingly, female preference patterns for one call component can vary with the expression of another. These results do not explain why dominant frequency did not account for any variation in male mating success under field conditions.Communicated by T. Beschlitz     

Mate preferences in <Emphasis Type="Italic">Drosophila</Emphasis> infected with <Emphasis Type="Italic">Wolbachia</Emphasis>?

The maternally inherited bacterium Wolbachia pipientis generates strong reproductive incompatibilities between uninfected females and infected males (cytoplasmic incompatibility), significantly reducing both female and male reproductive success. Such fitness costs are thought to place selective pressure on hosts to evolve pre-copulatory preferences for mating with compatible mates, thereby enabling them to avoid the reproductive incompatibilities associated with Wolbachia. Therefore, uninfected females are predicted to prefer mating with uninfected males, whereas infected males are predicted to prefer mating with infected females. Despite these predictions, previous investigations of pre-copulatory mate preferences in Wolbachia-manipulated Drosophila have not found evidence of female preference for uninfected or compatible males. However, none of these studies utilised a design where focal individuals are provided with a simple choice in a relatively non-competitive situation. We examined both female and male pre-copulatory mate preference based on mate infection status in Drosophila simulans and D. melanogaster using simple choice assays involving between 30–50 replicates per treatment. Although we found no evidence of female pre-copulatory mate preferences in either species, male D. simulans exhibited some preference for mating with females of the same infection status. However, this preference was not evident when we repeated the experiment to confirm this finding. Consequently, we conclude that neither male nor female D. melanogaster and D. simulans exhibit significant Wolbachia-associated pre-copulatory mate preferences.     

The effect of rearing environment on blue structural coloration of eastern bluebirds (<Emphasis Type="Italic">Sialia sialis</Emphasis>)

We used a brood-size manipulation to test the effect of rearing environment on structural coloration of feathers grown by eastern bluebird (Sialia sialis) nestlings. Ultraviolet (UV)-blue structural coloration has been shown to be sexually selected in this species. Our experimental design took advantage of the growth of UV-blue wing feathers in nestlings that are retained as part of the first nuptial plumage. We cross-fostered nestlings to create enlarged and reduced broods with the purpose of manipulating parental feeding rates and measured the effect on nestling growth and plumage coloration. Brood size influenced feeding rates to offspring, but the effect varied with season. In general, male nestlings reared in reduced broods were fed more often, weighed more, and displayed brighter structural plumage compared to nestlings reared in enlarged broods. Female nestlings appeared to experience less adverse affects of brood enlargement, and we did not detect an effect of brood-size manipulation on the plumage coloration of female nestlings. Measures of plumage coloration in both males and females, however, were correlated to hatching date and nestling mass during feather development. These data provide empirical evidence that environmental quality can influence the development of the blue structural coloration of feathers and that males may be more sensitive to environmental fluctuations than females.     

Designing Systematic Conservation Assessments that Promote Effective Implementation: Best Practice from South Africa

Abstract:  Systematic conservation assessment and conservation planning are two distinct fields of conservation science often confused as one and the same. Systematic conservation assessment is the technical, often computer-based, identification of priority areas for conservation. Conservation planning is composed of a systematic conservation assessment coupled with processes for development of an implementation strategy and stakeholder collaboration. The peer-reviewed conservation biology literature abounds with studies analyzing the performance of assessments (e.g., area-selection techniques). This information alone, however, can never deliver effective conservation action; it informs conservation planning. Examples of how to translate systematic assessment outputs into knowledge and then use them for "doing" conservation are rare. South Africa has received generous international and domestic funding for regional conservation planning since the mid-1990s. We reviewed eight South African conservation planning processes and identified key ingredients of best practice for undertaking systematic conservation assessments in a way that facilitates implementing conservation action. These key ingredients include the design of conservation planning processes, skills for conservation assessment teams, collaboration with stakeholders, and interpretation and mainstreaming of products (e.g., maps) for stakeholders. Social learning institutions are critical to the successful operationalization of assessments within broader conservation planning processes and should include not only conservation planners but also diverse interest groups, including rural landowners, politicians, and government employees.     

Fitness consequences of body-size-dependent host species selection in a generalist ectoparasitoid

In insect parasitoids, offspring fitness is strongly influenced by the adult females choice of host, particularly in ectoparasitoids that attack non-growing host stages. We quantified the fitness consequences of size-dependent host species selection in Dirhinus giffardii, a solitary ectoparasitoid of tephritid fruit fly pupae. We first showed a positive correlation between the size of emerged D. giffardii wasps and the size of their host fruit fly species (in order of decreasing size): Bactrocera latifrons, B. cucurbitae, B. dorsalis or Ceratitis capitata. We then manipulated individual wasps to show that the parasitoid preferred to attack the largest (B. latifrons) to the smallest (C. capitata) host species when provided with a choice, and laid a greater proportion of female eggs in B. latifrons than in C. capitata. There were no differences in developmental time or offspring survival between individuals reared from these two host species. Finally, we compared the foraging efficiency of large versus small wasps (reared from B. latifrons vs C. capitata) under two different laboratory conditions: high versus low host habitat quality, given that realized fecundity in parasitoids may be influenced by either egg-limited or time-limited factors. Under both conditions, large wasps parasitized more hosts than did small ones as a consequence of high searching efficiency in the host-poor habitat, and high capacity for adjusting egg maturation in response to host availability in the host-rich habitat. Considering the flexibility of body growth, the apparent lack of cost of achieving large body size in either development or survival, and the strong dependence of realized reproductive success on a females size, we argue that body size may be a key to understanding evolution of host species selection in ectoparasitoids. We also discuss constraints upon the evolution of size-dependent host species selection in parasitoids.Communicated by D. Gwynne     

Antennal responses of four species of tree-killing bark beetles (Coleoptera: Scolytidae) to volatiles collected from beetles,and their host and nonhost conifers

Summary. Host selection in tree-killing bark beetles (Coleoptera: Scolytidae) is mediated by a complex of semiochemical cues. Using gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses, we conducted a comparative study of the electrophysiological responses of four species of tree-killing bark beetles, the Douglas-fir beetle, Dendroctonus pseudotsugae, Hopkins, the mountain pine beetle, D. ponderosae Hopkins, the spruce beetle, D. rufipennis Kirby, and the western balsam bark beetle, Dryocoetes confusus Swaine, to volatiles captured by aeration of 1) bole and foliage of four sympatric species of conifers, Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, lodgepole pine, Pinus contorta var. latifolia Engelm., interior spruce, Picea engelmannii x glauca, and interior fir, Abies lasiocarpa x bifolia, and 2) con- and heterospecific beetles at three stages of attack. We identified 13 monoterpenes in the conifers and nine compounds in the volatiles of beetles that elicited antennal responses. There was no qualitative difference in the terpene constitution of the four species of conifers and very little difference across beetle species in their antennal response to compounds from conifers or beetles. The lack of species-specific major or minor components in conifers suggests that beetles would need to detect differences in the ratios of different compounds in conifers to discriminate among them. Attraction to hosts and avoidance of nonhost conifers may be accentuated by perception of compounds emitted by con- and heterospecific beetles, respectively. The 22 compounds identified are candidate semiochemicals with potential behavioural roles in host location and discrimination.     

Effects of kinship on territorial conflicts among groups of lions,<Emphasis Type="Italic"> Panthera leo</Emphasis>

Inclusive fitness theory predicts that cost of tolerant behaviour during competitive interactions is lower for relatives than for nonrelatives. Many studies have examined the effect of relatedness on behaviour within social groups. In contrast, kin selection acting among groups has received less attention. The genetic structure of African lion (Panthera leo) populations creates a strong possibility that kin selection among groups modifies behaviour during group conflicts. We used playback experiments and genetic data to investigate the importance of relatedness during simulated territorial disputes in lions. However, we found no effect of relatedness on territorial behaviour. Degree of relatedness did not affect the decision to approach simulated intrusions, nor did it affect the behaviour during approaches. The decision to approach was instead affected by position within the territory and consecutive playback number (a measure of habituation). For playbacks that did elicit an approach, the speed of response was not detectably affected by relatedness, but was affected by odds (the ratio of residents to intruders), number of intruders, number of bouts, presence of cubs, position within the territory, temperature and playback number. Although responses were unaffected by relatedness, it remains possible that other aspects of behaviour during natural encounters among prides are affected by kin selection.Communicated by L. Sterck     

Bat serenades—complex courtship songs of the sac-winged bat (<Emphasis Type="Italic">Saccopteryx bilineata</Emphasis>)

Vocalisations of many songbirds, anurans, and insects are shaped by sexual selection. Males acoustically compete for territories, and females choose their mates by means of male courtship songs. In courtship, richness and complexity of elements are often favoured characters. Only a few examples of complex songs are known in mammals. Males of the harem-polygynous sac-winged bat (Saccopteryx bilineata, Emballonuridae) have an uncommonly complex vocal repertoire, and different song types of males are used in the context of territorial defence and in courting females. We classified the daytime vocalisations of 16 male S. bilineata from a colony in Costa Rica, both on the basis of their acoustical properties and the social context in which they occurred. Seven vocalisation types were differentiated: echolocation pulses, barks, chatter, whistles, screeches, territorial songs and courtship songs. Territorial songs were short, rather stereotyped and not obviously directed towards a certain conspecific. They appear to be of importance in male competition for harem territories, in which females roost during the day. Courtship songs were exclusively observed when males displayed towards a female; they were long and complex, and consisted of highly variable elements (calls). We classified the calls in courtship songs of six males into call types, based on acoustical properties, mainly spectral purity and duration. Four call types are described in detail: trills, noise-bursts, short tonal calls, and quasi constant frequency calls. Twelve parameter values were extracted from the most common call type, the trill. Discriminant function analysis of trills showed that different males had different repertoires. This could allow females to use trill parameters for recognition of individual males and thus for mate choice.Communicated by G. Wilkinson     

Effect of queen quality on interactions between workers and dueling queens in honeybee (Apis mellifera L.) colonies

The fitness of a social insect colony depends greatly on the quality (i.e., mating ability, fecundity, and offspring viability) of its queen(s). In honeybees, there is marked variation in the quality of young queens that compete in a series of lethal duels to replace a colonys previous queen. Workers interact with queens during these duels and could increase their inclusive fitness by biasing the outcomes of the duels in favor of high-quality queens. We predicted that workers will have more antagonistic interactions (chasing, grabbing, clamping) and fewer beneficent interactions (feeding, grooming) with low-quality than high-quality queens. To test this prediction, we reared queens from 0-day-old, 2-day-old, and 3-day-old worker larvae in observation colonies undergoing queen replacement, thus producing high-quality, low-quality, and very low-quality queens, respectively. Immediately after each queen emerged, we observed her for 1 h to record her interactions with the workers. Subsequent morphological measurement of the queens confirmed that initial larval age had a significant effect on queen quality. However, there was no consistent effect of queen quality on the rates of worker–queen interactions, thus falsifying our hypothesis. The mean power of our tests was high (0.599), therefore the probability of a type II error (a false negative) is low. We conclude that if workers actively select high-quality queens, then they do so prior to queen duels, during queen development. We suggest that each worker–queen interaction has a distinct adaptive significance rather than forming a suite of behavior that favors particular queens (e.g., chasing repels any queen that approaches a queen cell, thus protecting all queen cells from destruction).Communicated by M. Giurfa