Alternative mating tactics in male white-faced dragonflies (Leucorrhinia intacta): plasticity of tactical options and consequences for reproductive success

Summary Alternative tactics used by males to obtain mates usually are associated with genetic and/or phenotypic differences between the behavioral morphs. This system of white-faced dragonfly (Leucorrhinia intacta) alternatives is characterized by plasticity of tactical options for individual males. Males may act either as territorials, and defend small perch-centered territories on the study pond, or they act as transients, spending most of their time in vegetation surrounding the pond and sallying out at intervals in search of mates. The two tactics remain in constant proportions over a broad range of densities, so transients do not result only from a filling in of suitable territorial sites. Males adopt tactics independently from day to day, with no significant influences of phenotypic variation, priority of arrival at the breeding site, or prior success in a role. We interpret this system as based on conditional, frequency-dependent choice of alternatives by a population of males not differing significantly in their abilities to employ one tactic or the other, but we cannot exclude entirely the possibility of mixed strategies. Average daily mating success is equal for territorial and transient males, supporting predictions of mixed and conditional ESS hypotheses. Males of each tactic obtain matings daily in proportion to their representation in the population for most data samples. Deviations from the expected mating success provide no information of use in selecting one or the other tactic on subsequent days. We suggest this system of alternatives represents a conditional mating strategy, in which males adopt tactics based on the availability of perches relative to oviposition substrate and on interactions within and between tactics that are influenced by the relative frequencies of territorial and transient males.     

Bryozoan biodiversity in the New Zealand region and implications for marine conservation

Marine biodiversity and its distribution in the New Zealand region were determined using historical data for an appropriate indicator taxon, the Bryozoa. Bryozoans were identified as belonging to three communities, termed Intertidal/Shelf/Slope (ISS) and Deep-Sea 1 and 2 (DS1 and DS2). Biodiversity was assessed using measures based on relatedness of species, average taxonomic distinctness and variation in taxonomic distinctness. High values of biodiversity for the ISS community are particularly concentrated at both ends of two main islands of New Zealand; the biogenic substratum of the Three Kings Plateau and Foveaux Strait. High values of biodiversity for the DS1 community were primarily located on the seamounts of the northern edge of the Chatham Rise. Values of biodiversity for stations comprising the DS2 community were generally low. The relationship between bryozoan community composition/biodiversity and depth suggested that habitat availability/heterogeneity, sedimentary perturbation and primary productivity could be evoked to explain the pattern of biodiversity observed. The results of the study indicate particular areas of the shelf and deep-sea environment that could be protected in order to conserve New Zealand's marine biodiversity.     

New Zealand climate in the Neogene and implications for global atmospheric circulation

New Zealand has a good Neogene plant fossil record. During the Miocene it was without high topography and it was highly maritime, meaning that its climate, and the resulting vegetation, would be controlled dominantly by zonal climate conditions. Its vegetation record during this time suggests the climate passed from an ever-wet and cool but frostless phase in the Early Miocene in which Nothofagus subgenus Brassospora was prominent. Then it became seasonally dry, with vegetation in which palms and Eucalyptus were prominent and fires were frequent, and in the mid-Miocene, it developed a dry-climate vegetation dominated by Casuarinaceae. These changes are reflected in a sedimentological change from acidic to alkaline chemistry and the appearance of regular charcoal in the record. The vegetation then changed again to include a prominent herb component including Chenopodiaceae and Asteraceae. Sphagnum became prominent, and Nothofagus returned, but mainly as the subgenus Fuscospora (presently restricted to temperate climates). This is interpreted as a return to a generally wet, but now cold climate, in which outbreaks of cold polar air and frost were frequent. The transient drying out of a small maritime island and the accompanying vegetation/climate sequence could be explained by a higher frequency of the Sub-Tropical High Pressure (STHP) cells (the descending limbs of the Hadley cells) over New Zealand during the Miocene. This may have resulted from an increased frequency of ‘blocking’, a synoptic situation which occurs in the region today. An alternative hypothesis, that the global STHP belt lay at a significantly higher latitude in the early Neogene (perhaps 55°S) than today (about 30°S), is considered less likely because of physical constraints on STHP belt latitude. In either case, the difference between the early Neogene and present situation may have been a response to an increased polar-equatorial temperature gradient. This contrasts with current climate models for the geological past in which the latitude of the High Pressure belt impact is held invariant though geological time.     

Onion fly,Delia antiqua,oviposition and mating as influenced by insect age and dosage of male reproductive tract extract (Diptera: Anthomyiidae)

One hundred percent of virgin female onion flies,Delia antiqua, receiving 1/20 of a male equivalent of an aqueous extract of mature male reproductive tract remained unmated in the presence of males and began laying unfertilized eggs at a normally mated rate of about 20 eggs/female/day. The 50% behavioral response (BR₅₀) fell between 1/40 and 1/20 of a male equivalent. Sex peptide responses are not always all-or-none. Some females receiving extract at 1/40 male equivalent oviposited at an intermediate rate. Moreover, at low sex peptide dosages, some females were fully activated ovipositionally but were receiptive to mating. A low level of sex peptide was present in 1-day-old males. Sex peptide titer rose with age until plateauing by 6 days posteclosion. Males began mating at 3 days, when they first had ample mature sperm; 50% of 6-day-old males mated. The mean number of females inseminated per male exposed to an excess of virgin females over 24 h was 4.3±0.6 (±SE). Presence of mature eggs was not always a prerequisite for mating, although probability of insemination was correlated with egg maturation. One-day-old preovipositional females receiving 1/20 of a male equivalent of extract began ovipositing when they had mature eggs at 5–6 days old. Therefore, sex peptide may act early and permanently or have a long half-life and affect behaviors once females reach sexual maturity. Male flies provide females with an excess of sex peptide in many cases.D. antiqua males transferred ca. 5–10 times more sex peptide than necessary to activate females fully. We suggest this excess is related to the speed of female response. It is yet unclear whether sex peptide potency or titer in Diptera has become exaggerated by intra- or intersexual selection.     

A national survey of airborne pollen and grass flowering in New Zealand,with implications for respiratory disorder

Airborne pollen and spore levels were monitored at seven sites in New Zealand using the Intermittent Cycling Rotorod sampler during the summer of 1988/1989. Grasses formed the major component of atmospheric pollen levels during spring and summer at every locality. Peak levels of grass and total pollen occurred during December or late November, with a slight latitudinal lag apparent at the more southern sites. Highest levels were recorded at the smaller rural centres of Gore and Kaikohe and the lowest at the larger urban centres of Auckland, Christchurch and Wellington. We make a first approximation of the likely risk to hayfever and allergic asthma patients at each of the seven centres. For example, significantly higher grass pollen levels were experienced at Kaikohe on 44% and 65% of days during November and December, compared with just 15% and 8% at Auckland. By recording the flowering seasons of the principal allergenic grass species at each locality, we determined the potentially allergenic grasses contributing to peak pollen levels, the most ubiquitous being tall fescue (Festuca arundinacea Schreb.), ryegrass (Lolium perenne L.,L. multiflorum Lam.), cocksfoot (Dactylis glomerata L.), Yorkshire fog (Holcus lanatus L.) and sweet vernal (Anthoxanthum odoratum L.). Corresponding author. Deceased.     

Diversification of New Zealand weta (Orthoptera: Ensifera: Anostostomatidae) and their relationships in Australasia

New Zealand taxa from the Orthopteran family Anostostomatidae have been shown to consist of three broad groups, Hemiandrus (ground weta), Anisoura/Motuweta (tusked weta) and Hemideina-Deinacrida (tree-giant weta). The family is also present in Australia and New Caledonia, the nearest large land masses to New Zealand. All genera are endemic to their respective countries except Hemiandrus that occurs in New Zealand and Australia. We used nuclear and mitochondrial DNA sequence data to study within genera and among species-level genetic diversity within New Zealand and to examine phylogenetic relationships of taxa in Australasia. We found the Anostostomatidae to be monophyletic within Ensifera, and justifiably distinguished from the Stenopelmatidae among which they were formerly placed. However, the New Zealand Anostostomatidae are not monophyletic with respect to Australian and New Caledonian species in our analyses. Two of the New Zealand groups have closer allies in Australia and one in New Caledonia. We carried out maximum-likelihood and Bayesian analyses to reveal several well supported subgroupings. Our analysis included the most extensive sampling to date of Hemiandrus species and indicate that Australian and New Zealand Hemiandrus are not monophyletic. We used molecular dating approaches to test the plausibility of alternative biogeographic hypotheses for the origin of the New Zealand anostostomatid fauna and found support for divergence of the main clades at, or shortly after, Gondwanan break-up, and dispersal across the Tasman much more recently.     

Effects of temperature and diet on oviposition rate and development time of the New Zealand flower thrips, Thrips obscuratus

The life history of New Zealand flower thrips (Thrips obscuratus (Crawford), Thysanoptera: Thripidae) was studied using a simple laboratory rearing method. The effects of temperature and diet on oviposition rate and development time were examined. Oviposition rate increased with increasing temperature between 10°C and 25°C. Development time for individual instars and for total development decreased with increasing temperature between 10°C and 27°C. Total development time ranged from 50 days at 10°C (female) to 10 days at 27°C (male). The relationship between temperature and development rate was expressed as a straight line such that lower thresholds of development of between 4.2°C and 6.3°C were established for life stages. Adult lifespan increased with decreasing temperature between 10°C and 25°C and females lived longer than males. At 10°C and 25°C females lived for an average of 34 and 3 weeks respectively. Thrips supplied with pollen exhibited highest and sustained levels of egg production in comparison to other diets. Larval mortality was lowest and development time fastest on diets of pollen and sucrose or fruit juice in comparison to other plant tissues. Larval development time was similar on four species of pollen.     

The biogeography of three Boeckella species (Copepoda: Calanoida) in New Zealand

The New Zealand distributions of three species of Boeckella (Copepoda, Calanoida), B. triarticulata, B. dilatata and B. hamata are mapped. B. triarticulata is primarily a pond dweller but is also found in reservoirs and shallow lakes. B. dilatata is mainly found in the deeper glacial lakes and ponds in the central region of the South Island and B. hamata has a more widespread distribution in lakes and ponds in the South Island and lower half of the North Island. Differences in temperature optima, food requirements and dispersal ability among the three Boeckella species are related to vicariant events to explain their distribution in New Zealand.     

Behavioural switch of female Mediterranean fruit fly, Ceratitis capitata: mating and oviposition activity in outdoor field cages in Hawaii

1 Laboratory-reared normal, and wild female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were assayed in outdoor field cages to assess the impact of a mating-induced behavioural switch on mating and subsequent oviposition activity. 2 Virgin females preferred interactions with males leading to mating over attraction to, and oviposition in, artificial yellow spheres containing guava odour or green apples hung in a guava tree. Laboratory-reared females previously mated with either laboratory-reared normal males or laboratory-reared irradiated (sterile) males showed little interest in remating with males and instead, were much more likely to be found arrested on artificial and real fruit and ovipositing. Oviposition on artificial fruit was five times greater by females that had mated with either normal or irradiated males than by virgin females. Wild females showed similar qualitative changes in the mating-induced behavioural switch; however, oviposition activity was significantly less than for laboratory-reared females. 3 These results confirm that mating has a profound effect on the behaviour of female Mediterranean fruit flies and that irradiated males are functionally equal with normal males (lab-reared or wild) in their ability to alter female behaviour. These results are discussed in the context of the sterile insect technique for control of Mediterranean fruit flies in the field.     

Eye and clasper damage influence male mating tactics in the horseshoe crab, Limulus polyphemus

In the horseshoe crab mating system, mated pairs are frequently accompanied by unattached satellite males as they spawn on intertidal beaches. Previous studies have shown that males locate females visually using their lateral (compound) eyes, and that attached (mated) males generally have less heavily worn or damaged carapaces than unattached males. The purpose of this study was to investigate the influences of lateral eye condition and clasper abnormalities on male mating tactics. Sexually mature males had two kinds of eye damage: deterioration caused by disease, and overgrowth by sessile invertebrates, such as bryozoans, mussels, and tube-building polychaetes. The lateral eyes of attached males had significantly less decay than unattached males. On the other hand, coverage of the lateral eyes by encrusting invertebrates was more extensive among attached than unattached males. Although overgrowth did not appear to impair a males ability to pair with a female as severely as eye decay, it is conceivable that amplexus may have occurred before epibiont coverage was sufficient to obscure vision. Male crabs that were experimentally blindfolded by painting their lateral eyes with black nail polish were less likely to reattach to a female than controls. Appendage injuries were more frequent among unattached males than among attached males; in particular, 6.4% of unattached males but 0.0% of attached males had damaged claspers (the modified first legs required for amplexus). Unattached males in the population were older, as judged by the degree of carapace wear, than attached males. Severe visual impairment and/or clasper damage may explain the reduced pairing success of older male horseshoe crabs, and underlie their choice of the alternative satellite male mating tactics.     

Conceiving Reproduction: New Reproductive Technologies and the Redefinition of the Kinship Narrative in New Zealand Society

This paper focuses on technologies for assisting conception and considers how normative notions of conception and family formation have informed the rejection, incorporation and adaptation of technologies and their regulation in New Zealand. Drawing on a textual analysis of primary written materials and secondary sources generated between 1965 and 2004, the paper reveals how these technologies help various groups in New Zealand society make explicit their understandings of relatedness, identity and social and cultural belonging. Whilst biological/genetic connection and social connections inform understandings of kinship, reproduction, parenthood and social structure for many New Zealanders, the boundaries between the biological and social are often blurred and precedence of one over the other is very much context dependent. The incorporation of the new reproductive technologies has been an inherently politicised process, with barriers to access to these technologies emerging in relation to ethnic identity and race, sexuality, socioeconomic status, gender, and marital status.     

Subordinate male meerkats prospect for extra-group paternity: alternative reproductive tactics in a cooperative mammal

In cooperatively breeding species, subordinates typically suffer strong constraints on within-group reproduction. While numerous studies have highlighted the additional fitness benefits that subordinates might accrue through helping, few have considered the possibility that subordinates may also seek extra-group matings to improve their chances of actually breeding. Here, we show that subordinate males in cooperative meerkat, Suricata suricatta, societies conduct frequent extraterritorial forays, during periods of peak female fertility, which give rise to matings with females in other groups. Genetic analyses reveal that extra-group paternity (EGP) accrued while prospecting contributes substantially to the reproductive success of subordinates: yielding the majority of their offspring (approx. 70%); significantly reducing their age at first reproduction and allowing them to breed without dispersing. We estimate that prospecting subordinates sire 20-25% of all young in the population. While recent studies on cooperative birds indicate that dominant males accrue the majority of EGP, our findings reveal that EGP can also arise from alternative reproductive tactics employed exclusively by subordinates. It is important, therefore, that future attempts to estimate the fitness of subordinate males in animal societies quantify the distribution of extra-group as well as within-group paternity, because a substantial proportion of the reproductive success of subordinates may otherwise go undetected.     

Inbreeding depression and mixed mating in Leptosiphon jepsonii: a comparison of three populations

BACKGROUND AND AIMS: Inbreeding depression is thought to play a central role in the evolution and maintenance of cross-fertilization. Theory indicates that inbreeding depression can be purged with self-fertilization, resulting in positive feedback for the selection of selfing. Variation among populations of Leptosiphon jepsonii in the timing and rate of self-fertilization provides an opportunity to study the evolution of inbreeding depression and mating systems. In addition, the hypothesis that differences in inbreeding depression for male and female fitness can stabilize mixed mating in L. jepsonii is tested. METHODS: In a growth room experiment, inbreeding depression was measured in three populations with mean outcrossing rates ranging from 0.06 to 0.69. The performance of selfed and outcrossed progeny is compared at five life history stages. To distinguish between self-incompatibility and early inbreeding depression, aborted seeds and unfertilized ovules were counted in selfed and outcrossed fruits. In one population, pollen and ovule production was quantified to estimate inbreeding depression for male and female fitness. KEY RESULTS: Both prezygotic barriers and inbreeding depression limited self seed set in the most outcrossing population. Cumulative inbreeding depression ranged from 0.297 to 0.501, with the lowest value found in the most selfing population. Significant inbreeding depression for early life stages was found only in the more outcrossing populations. Inbreeding depression was not significant for pollen or ovule production. CONCLUSIONS: The results provide modest support for the hypothesized relationship between inbreeding depression and mating systems. The absence of early inbreeding depression in the more selfing populations is consistent with theory on purging. Differences in male and female expression of inbreeding depression do not appear to stabilize mixed mating in L. jepsonii. The current estimates of inbreeding depression for L. jepsonii differ from those of previous studies, underscoring the effects of environmental variation on its expression.     

Genetic structure of lions (Panthera leo L.) in the Selous Game Reserve: implications for the evolution of sociality

Abstract We use 14 microsatellites to examine the genetic structure of a lion (Panthera leo L.) population in southern Tanzania. Heterozygosity levels were high (0.75 ± 0.08). Relatedness estimates showed that prides often had close relatives in neighbouring prides, whereas few relatives were found in prides not sharing a border. The drop‐off in relatedness with distance was highly significant. Female pridemates exhibited a higher mean relatedness (0.26 ± 0.07) to one another than did pride males (0.11 ± 0.07). Mean relatedness among females was significantly higher in small prides than in large ones. Prides exhibited significant inbreeding avoidance (F_IL: ?0.11). Mating did not detectably differ from random across prides (F_IT: ?0.02 ns). In addition to being recognizable behavioural and demographic units, prides were statistically distinct genetic units (F_LT: 0.07). Some neighbouring prides grouped together both geographically and genetically, forming ‘superprides’ in the population (F_ZT = 0.05). Thus, although individual prides were genetically distinct, there was an important genetic structure above the level of social groups.     

An appraisal of simple tree-mounted shelters for non-lethal monitoring of weta (Orthoptera: Anostostomatidae and Rhaphidophoridae) in New Zealand nature reserves

When monitoring rare insect species, or when surveying faunas within nature reserves, it is desirable not to use indiscriminate lethal sampling techniques. In this investigation we assessed the usefulness of simple tree-mounted wooden shelters to monitor endemic weta (Orthoptera) in nature reserves in Canterbury, New Zealand. Fifty shelters were placed out at six sites and examined at three-monthly intervals for a year. A wide variety of invertebrates were found utilizing the shelters, with Arachnida, Blattodea and Collembola being the most common occupants. After three months over 80% of the shelters exhibited signs of use by invertebrates, increasing to 96% after 12 months. Only seven tree weta (Anostostomatidae) and one (dead) ground weta (Hemiandrus sp.) were observed in the shelters over the full 12 month period. There were 52 observations of cave weta (Rhaphidophoridae) in the shelters, 36 of which occurred at one site, Orton Bradley Park. Occupation of the shelters by cave weta was not affected by soil conditions, light intensity or aspect of the shelter. However, cave weta exhibited a preference for shelters less than 50 cm above the ground and for shelters attached to kanuka and vines. Although weta were found in only a small proportion (9%) of the shelters, this method proved useful in confirming the presence of weta without risk of harming vulnerable populations. These shelters are inexpensive and easy to manufacture and have potential for long-term non-lethal monitoring of weta and as a collection/carriage device for live specimens used in conservation translocations.     

Body size,male aggression,and male mating success in the cottonwood borer,Plectrodera scalator (Coleoptera: Cerambycidae)

The natural history and mating system ofPlectrodera scalator exhibit several unusual characteristics. Larvae and adults feed on the wood and foliage, respectively, of the same plant,Populus deltoides. The population sex ratio, based on censuses of oviposition areas, is female-biased. Females are significantly larger than males, yet males are intensely aggressive. Larger males tend to win escalated battles, which involve grasping of antennae with mandibles, but smaller males can defeat larger males if they grasp their opponent's antenna first. Most escalated fights involve possession of a female, but prior possession does not play a role in determining the outcome of these fights. The size-dependent fighting advantage does not translate into a mating advantage for larger males. There is no significant difference in elytron length or body mass between mating and single males. Larger females are not preferred as mates. The mating system appears to be a mixture of female-defense and scramble-competition tactics. One advantage to males of aggression may be in its effect on sperm precedence. Males appear to be able to remove previously deposited sperm from a female's reproductive tract.     

Environmental safety of biological control: Policy and practice in New Zealand

Introduction of biological control agents into New Zealand is regulated under the Hazardous Substances and New Organisms Act 1996 (HSNO). The legislation is strongly focused on the health and safety of people and the environment. HSNO is implemented by the Environmental Risk Management Authority, a quasi-judicial body of 6–8 people appointed by the Minister for the Environment. The process by which biological control applications are received and processed is described. Two case studies of weed biological control agents which have been through the HSNO process, and the scientific issues that arose in considering the environmental safety of these agents are discussed. The case studies presented are the applications to release the gall fly Procecidochares alani (Diptera: Tephritidae) to control mist flower Ageratina riparia, and three biological control agents, Macrolabis pilosellae (Diptera: Cecidomyiidae), Cheilosia urbana, and Cheilosia psilophthalma (Diptera: Syrphidae) for biological control of hawkweeds (Hieracium spp.). Both applications were approved for agent release into the environment.