Age, growth and mortality of red bandfish, Cepola macrophthalma (L.), in the eastern Adriatic Sea (Croatian coast)

Age, growth and mortality were analysed for red bandfish, Cepola macrophthalma, collected in the eastern Adriatic from May 2002 to June 2003. The oldest male was estimated to be age 4, the oldest female age 3. Parameters of the von Bertalanffy growth equation are: L_∞ = 55.0 cm (SE = 0.1), K = 0.445 (SE = 0.074) and t₀ = ?0.1 (SE = 0.001) for males, and L_∞ = 48.9 cm (SE = 0.167), K = 0.395 (SE = 0.062) and t₀ = ?0.009 (SE = 0.02) for females. The overall sex ratio was 1.42 : 1 in favour of males. Total mortality, corresponding to the slope of the descending limb of the catch curve, was Z = 1.20 per year for females and Z = 1.23 per year for males. Exploitation ratios were E = 0.479 for females and E = 0.433 for males.     

The effect of interspecific mating on sex ratios in the twospotted spider mite and the Banks grass mite (Acarina: Tetranychidae)

Mixed populations of the twospotted spider mite (TSM),Tetranychus urticae (Koch), and the Banks grass mite (BGM),Oligonychus pratensis (Banks), occur on corn and sorghum plants in late summer in the Great Plains. Interspecific matings between these arrhenotokous species occur readily in the laboratory but yield no female offspring. The effect of interspecific mating on female: male sex ratios was measured by examining the F₁ progeny of females that mated with both heterospecific and conspecific males in no-choice situations. TSM females that mated first with BGM males and then with TSM males produced a smaller percentage of female offspring than TSM females that mated only with TSM males (43.1±5.8 and 78.9±2.8% females, respectively). Similarly, BGM females mated with heterospecific males and then with conspecific males produced fewer female offspring than females mated only with BGM males (55.7±5.2 and 77.5±2.5%, respectively). Lower female: male sex ratios were produced also by BGM females that mated with TSM males after first mating with conspecifics (62.4±3.4%). In mixed populations containing males of both species, females also produced lower female: male sex ratios, but these ratios were not as low as expected based on mating propensities and progeny sex ratios observed in no-choice tests. These data suggest that interspecific mating may substantially reduce female fitness in both mite species by reducing the output of female offspring, but in mixed populations this effect is mitigated by unidentified behavioral mechanisms.     

Population structure and reproductive biology of Atlantoscia floridana (van Name, 1940) (Crustacea, Isopoda, Oniscidea) in southern Brazil

Data were obtained on the population structure and reproduction of Atlantoscia floridana, one of the most common species of terrestrial isopods in the restinga (coastal dune) forests of the state of Rio Grande do Sul, southern Brazil. During a 19-month period, a total of 7833 individuals were sampled: 2792 males, 3400 females and 1691 mancas. There was a significant difference between the size of both males and females collected in 2000 and 2001: the mean size was smaller in the second year when individuals in the larger size classes were lacking. Population density varied with season. The minimum population was 131 ind per m² individuals, the maximum 1040 ind per m² and the mean 450  per m². While the overall sex ratio was clearly female biased, the operational sex ratio favored males, and showed no changes with season. Because both ovigerous and post-ovigerous females were present throughout the year, reproduction is considered continuous; however, reproduction peaked during autumn and spring. Ovigerous females were measured (CW = cephalothorax width) and the number of eggs was counted. Fecundity (F) varied from 5 to 23 eggs ( = 11.18 ± 4) per female, and was expressed by the regression F = –18.48 + 22.59 CW, with the female cephalothorax width varying from 1.04 to 1.68 mm. Marsupial mortality was only 0.9%. Egg production was 588 eggs per m² in spring and 660 eggs per m² in autumn. Recruitment occurred in all months, and eggs, embryos and marsupial mancas were also present year-round. A. floridana is the dominant species of terrestrial isopod in the study area. Its most remarkable characteristic is its high reproductive investment.     

The adaptive significance of mate guarding in the soapberry bug,Jadera Haematoloma (Hemiptera: Rhopalidae)

Male soapberry bugs (Jadera haematoloma)face severe mating competition at the northern edge of their range due to male-biased adult sex ratios. Copulations lasting up to 11 days may serve a mate guarding function (encompassing four or more ovipositions), but copulation duration is highly variable, with some pairings lasting as little as 10 min. Data were gathered to describe factors that influence the reproductive costs and benefits of prolonged copulation. Estimated copulation durations (mean ± SD) were 20 ± 23 h in the lab and 50 ± 8 h in the field and were only weakly affected by sex ratio. Females mated for 5 min produced as many fertile eggs as those mated for 600 min laid; they became depleted of fertile sperm after about 25 days. In twicemated females, the first male's paternity was reduced by about 60%, and all females (N = 13) whose mates were removed experimentally mated again within an average of 6 min. The outcome of sperm competition on a perclutch basis was not highly predictable. The possibility of increased sperm displacement in longer copulations was not tested. Males often guarded females during oviposition and successfully defended them from intruding single males by recopulating. Such intrusions occurred in the majority of oviposition attempts observed in nature. Even though most females mated promiscuously, in a focal aggregation with a mean sex ratio of 2.2 ± 0.4 males/female, the interval between matings by males was commonly several days. Males appeared to respond facultatively to several aspects of the distribution and availability of females. The intensities of mating competition and sperm competition indicate that monogamous mate guarding should be favored over nonguarding in nature. Unpredicted brief. pairings may result from assessment by males of female reproductive value or of their own physical condition, or from female resistance.     

Lion (Panthera leo) demographics in the south-western Kgalagadi Transfrontier Park

Changes in demographic features of the lion population in the south-western Kgalagadi Transfrontier Park cause conservation concern. The ratio between adult males and females changed from 1♂:2♀ to 1♂:1♀ over a 32-year period (1977–2010). This is atypical for undisturbed lion populations. We evaluated mechanisms that on their own or together could explain the trend by using both a discrete- and continuous-time capture–recapture model to analyse 2 years of individual-based observation data (May 2013–June 2015). Although most vital rates were within expected parameters, shifts in the sex structure remained similar to that reported for sub-adults previously. The population comprised of 26.9% cubs and juveniles (<2 years), 14.2% sub-adults (2–4 years) and 59% adults (>4 years). Litters had equal sex ratios at first detection. Birth rates were lower (0.44 cubs per female per year) than between 1998 and 2001 (0.69 cubs per female per year). The continuous model indicated a higher survival effect for female cubs, while both models showed higher survival rates/effects for sub-adult and adult females relative to males. However, the sex ratio for sub-adults was male-biased. The shift in demographic signals may associate with changes in age-related immigration rates of sub-adult males.     

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.     

Mating Behavior and Reproductive Potential in the Turnip Moth Agrotis segetum (Lepidoptera: Noctuidae)

We investigated the lifetime mating potential and the reproductive behavior of male and female turnip moths Agrotis segetum (Schiff.) under field and laboratory conditions. The sex ratio was 1 : 1 in a lab-reared population as well as in two wild populations. Males were capable of mating repetitively a relatively large number of times (mean of 6.7 ± 2.7 matings) when given access to new virgin females throughout their lifetimes. Females seldom mated more than once (mean ± 1.3 ± 0.6 matings), indicating a male-biased operational sex ratio. The mean potential lifetime mating was five times higher in males, while the coefficient of variance was lower in males. There was no differences in longevity between animals that were allowed to mate and animals not allowed to mate, indicating no direct costs or benefits of mating in physiological terms. In males, the number of matings was positively correlated with longevity, but this was not the case in females. Nor was there a correlation between the number of female matings and the number of fertilized eggs. There was a negative correlation between the number of eggs fertilized and the number of times males had previously mated, indicating that male ejaculates were limited. Male spermatophore size also decreased with number of achieved matings. Laboratory-reared females attracted males in the field throughout their lifetimes, with a peak at 3–7 days of age. Wild males, allowed to choose between pairs of caged females in the field, were attracted in equal numbers to females of different ages. Females did not show any mate-rejection behavior in the field. They mated with the first male that courted them. No incidence of mate replacement by males arriving later to already courted females were recorded.     

Age,growth and mortality of common two‐banded seabream,Diplodus vulgaris (Geoffroy Saint‐Hilaire, 1817), in the eastern Adriatic Sea (Croatian coast)

Age, growth and mortality were analysed for the common two‐banded seabream, Diplodus vulgaris, collected in the eastern Adriatic (Croatian coast) from commercial fishery catches by ‘tramata’ fishing (2005–2006) to obtain growth estimation. The oldest female was estimated to be age 11, the oldest male age 10 years. The von Bertalanffy growth parameters estimated by reading scales were: L_∞ = 48.60 cm (SE = 1.101), K = 0.112 (SE = 0.005) and t₀ = ?2.366 (SE = 0.060) for all specimens; L_∞ = 51.96 cm (SE = 2.153), K = 0.095 (SE = 0.007) and t₀ = ?2.837 (SE = 0.120) for females and L_∞ = 56.25 cm (SE = 2.662), K = 0.084 (SE = 0.067) and t₀ = ?2.920 (SE = 0.117) for males. The overall sex ratio was 1.22 : 1 in favour of males. Total mortality, corresponding to the slope of the descending limb of the catch curve, was Z = 0.81 per year for females and Z = 0.85 per year for males. Exploitation ratios were E = 0.68 for females and E = 0.73 for males.     

Life history studies of <Emphasis Type="Italic">Prorops nasuta</Emphasis>, a parasitoid of the coffee berry borer

Life history studies were conducted in the laboratory on the African parasitoid Prorops nasuta Waterston (Hymenoptera: Bethylidae), a parasitoid of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae). The female wasp enters an infested coffee berry, kills the adult borer and seals the entrance of the berry with the body of the borer, impeding the entry of other organisms into the berry. The preoviposition period ranges from 3 to 14 days (mean 5.42 ± 0.37 SE). During this time females feed on the immature stages and paralyse fully grown larvae and pupae of the CBB. P. nasuta is an idiobiont solitary ectoparasitoid. Eggs are laid externally on the last instar larvae and pupae. Mean development time (egg to adult) for males and females was 27.7 (±0.37 SE) and 30 (±0.12 SE) days, respectively. Median survival for wasps fed on final instar CBB larvae was 27.7 days, significantly longer than any other treatment, while for females without food it was 2.5 days. In culture, females produced an average of 4.3 (±0.39 SE) progeny during their lifetimes. Adults began emerging at 30.6 days (±0.28 SE) after cultures were started and peak production was reached at 36 days, declining thereafter. Males normally emerged from coffee beans 2–3 days before females. Males usually emerged from 07:00 to 09:00h and females from 10:00 to 14:00 h. The culture sex ratio (proportion of males) was 0.21. Virgin females produced only male offspring.     

Food Shortage Disrupts Social Organization: The Case of Red Squirrels in Conifer Forests

A recent conceptual model of spatial organization in vertebrates, based upon changes in home range overlap with habitat quality, ‘the space-use model’, predicts large and strongly overlapping home ranges and absence of territorial behaviour in habitats with poor food availability. We investigated whether the model can be extended to predict intra-population variation in space-use in a habitat with strong temporal variation in resource abundance. We studied space use of Eurasian red squirrels (Sciurus vulgaris) in subalpine conifer forests over 4 years with strong fluctuations in seed production. Norway spruce dominated forests are resource limited habitats for squirrels, and tree seed availability is gradually depleted in the year following a poor seed-crop. Male and female squirrels responded to spruce seed-crop failure in 2000 by strongly increasing their home ranges and core-areas in the following year (mean MCP ± SE in summer and autumn, respectively: 2001, 122.9±14.1 ha and 84.3±9.4 ha, against 43.0±6.4 ha and 20.8±3.8 ha in 2002, and 22.7±1.5 ha and 21.4±2.0 ha in 2003). In 2001, half of the animals, those with the poorest quality pre-dispersal home ranges, emigrated to areas with more larch. Residents had multi-nuclear core-areas. Also, intra-sexual core-area overlap (males by males, females by females) was higher in 2001 and summer 2002, than in autumn 2002 and in 2003 (means ± SE in summer and autumn, respectively: males by males, 2001, 52±8 and 44±7%, 2002, 80±30 and 15±11%, 2003, 37±19 and 26±14%; females by females 2001, 52±10 and 112±32%, 2002, 55±27 and 0±0%, 2003, 12±8 and 0.1±0%). Red squirrels responded to food shortage by moving to patches with other food resources and abandoned the spacing pattern of reduced core-area overlap among males and nearly exclusive core-areas among females, found in less variable habitats. After richer seed-crops in 2001 and 2002, it took squirrels about a year to reduce the size of their home ranges and core-areas and return to a spacing pattern of stable home ranges and intra-sexual territoriality of adult females. These results are consistent with the space-use model and show that spacing behaviour in red squirrels is a plastic, conditional strategy with individuals adapting the size and/or location of their home ranges in relation to local distribution and abundance of food resources.Co-ordinating editor: R. Härdling     

Development, survival and fecundity of the urine fly, Scatella (Teichomyza) fusca and predation by the black dumpfly, Hydrotaea aenescens

Development, survival and fecundity for Scatella (Teichomyza) fusca Maquart (Diptera: Ephydridae) were studied at 20 ± 1 °C and 85 ± 10% r.h. Mean (± S.E.) developmental times of eggs, larvae and pupae were 4.0 ± 0.06, 14.9 ± 0.19 and 14.6 ± 0.11 days, respectively, the mean (± S.E.) survival of the original egg cohort to the start of larval, pupal and adult stage being 77.2 ± 3.2%, 54.5 ± 2.6% and 47.9 ± 3.5%, respectively. Females and males displayed approximately straight survivorship curves during adult life, implying constant mortality rates. Mean (± S.E.) adult longevity was 41.6 ± 2.98 days for females and 51.2 ± 3.91 days for males. Assuming a stable age distribution the population consisted of 56% eggs, 31% larvae, 6% pupae and 7% adults. Oviposition peaked when females were 25 days old, and the highest reproductive values (RV_x) (mean ± S.E.) ranged from 129.1 ± 7.57 to 138.5 ± 6.83 for individuals 17–27 days old. A female deposited a mean (± S.E.) of 614.7 ± 35.9 female eggs over a maximum life span of 93 days. The basic reproductive rate (R ₀) (mean ± S.E.) was 173.0 ± 14.2 female offspring per female and the intrinsic rate of natural increase of female individuals (r) (mean ± S.E.) was 0.088 ± 0.001 day^-1. The mean (± S.E.) generation time (T) was 57.8 ± 0.78 days. In cultures with equal numbers of first instar S. fusca larvae and predacious third instar larvae of Hydrotaea aenescens (synonymous Ophyra aenescens) Wiedemann, mean (± S.E.) survival to the adult stage of S. fusca (16.7 ± 8.8%) was significantly lower than in controls with S. fusca alone (58.3 ± 7.4%). The potential significance of predation by H. aenescens on S. fusca in pig farms is discussed.     

The reproductive ecology of resident manta rays (Manta alfredi) off Maui, Hawaii, with an emphasis on body size

In resident manta rays (Manta alfredi) off Maui, sexual maturity appears delayed until growth exceeds 90% of maximum size, an indicator that large body size provides a reproductive advantage at the expense of a shorter reproductive time period. In this study, 286 surveys were conducted between 2005 and 2010 using photo-identification and photogrammetry to study the reproductive ecology of a resident population of manta rays off Maui, Hawaii, and investigate the reproductive benefits of large body size in each sex. Although reproductive activities occurred year-round, mating trains and late-term pregnant females were significantly more likely to be observed during the winter months. Some females were pursued by males during both winter and summer of the same year, suggesting multiple ovulations may be possible in a single year. Males likely detect a female’s reproductive state by positioning directly behind her, or passing through her bodily excretions. The mean pregnancy rate was estimated at 0.56 pregnancies/adult female/year with larger females pregnant more often, and more likely in consecutive years. The operational sex ratio was heavily skewed with 2.68 adult males per reproductively available female. Although males appear to compete with one another for females within a mating train, no direct physical competition was ever observed between males. Evidence of highly dynamic mating trains lasting more than one day suggests endurance rivalry may be the primary mating strategy among males, during which larger males may benefit from greater energy reserves. The study area appears to be an important staging area for mating individuals in this population.     

Selection for altered pheromone-component ratios in the pink bollworm moth,Pectinophora gossypiella (Lepidoptera: Gelechiidae)

Female pink bollworm moths, Pectinophora gossypiella(Saunders), were selected for altered component ratios of the long-distance sex pheromone, (Z, E)-and (Z, Z)-7,11- hexadecadienyl acetate. Selection for 12 generations increased the mean (± SD) percentage of the (Z, E)isomer from 42.9 ± 1.0 in the parental generation to 48.2 ± 1.2. Although statistically significant, a change of this magnitude may be transparent to males because of their relatively broad response spectrum. Selection for a lower percentage of the (Z, E)isomer yielded no change in the mean pheromone ratio. The total amount of pheromone produced declined in both selected lines. In the line selected for females producing a high percentage of the (Z, E)isomer, the duration of wing fanning by males to high (Z, E)blends was elevated.     

Reproductive Parameters and Maternal Investment in Mandrills (Mandrillus sphinx)

We report on 14 years of reproductive data for semifree-ranging mandrills (Mandrillus sphinx) in Gabon, and we explore relationships between female rank, age and parity, and reproductive strategies. Most births (61% of 132) occurred during the wet season in Gabon, between January and March. Female rank and parity were unrelated to the timing of parturition. Gestation lengths average 175 days (SE = ±1 day; N = 61) and were similar irrespective of female rank, parity, or sex of offspring. Birth sex ratio did not differ significantly from unity (52% male), and was unrelated to maternal rank or parity. Stillbirths and neonatal mortality tended to be more common among lower-ranking females than among either mid-ranking or dominant females. Median age at first birth is 4.71 years, at a median body mass of 7.6 kg, ca 5 years before females attain their adult body mass (median 12 kg). Age at first reproduction is significantly correlated with dominance rank, with dominant females giving birth on average 1.3 years earlier than lower-ranking females do. Interbirth intervals (IBI) average 405 days (range 184–1159 days, N = 103), and are independent of the sex of the offspring. Infant death within 6 months shortened IBI to 305 days. Increasing age and parity are also associated with short IBI, as is higher rank. Maternal rank and parity appear to influence reproductive success in female mandrills, but there is no apparent differential maternal investment by sex.     

Some factors affecting reproduction and sex-ratio of the predacious mite Amblyseius deleoni (Muma and Denmark) (Acari: Phytoseiidae)

Abstract

Several factors were examined to determine their effect on the reproduction and sex ratio in the predacious mite Amblyseius deleoni (Muma and Denmark), in the laboratory. The factors investigated included multiple matings, duration of copulation, capacity of male for mating in excess of females and age of mating females and males. The factors included also, the host plant leaf texture, food deprivation during immature and adult stages, and prey (Tetranychus urticae Koch) density. The results indicated that females of A. deleoni require multiple matings to maximize their reproductive potential, also when copulation was allowed for increasing periods of time, there was a gradual increase in total egg production and oviposition period. A male showed a high reproductive ability for more than 15 days and was able to mate more than once in excess of females. Age of females has an influence on fecundity and sex ratio; old females decreased egg production and produced proportionally more male progeny compared with young females. Similarly, the highest number of eggs deposited per female A. deleoni was reported, when female mated with a young male (0-day old). In addition, males of A. deleoni (at any age) were able to inseminate the females. Results from host plant leaf texture indicated that guava leaf gave the highest reproduction rate, while the fig leaf gave the least female fecundity. Neither the reproductive rate nor the sex ratio of the progeny of females crossed by normal or experimental males had been influenced by the food deprivation during immature stages. A significant lower fecundity was recorded on female's A. deleoni when exposed to different food deprivation programmes during adult stage. The number of eggs laid by the predator female increased with increasing prey density of T. urtice to a maximum of 2.04 eggs deposited per day at a prey density of 30 protonymphs of T. urticae as a prey. As the level of prey density was increased, there was a shift in sex ratio towards an increased proportion of females.     

Population ecology of rhesus monkeys (Macaca mulatta) at Nanwan Nature Reserve,Hainan, China

Rhesus monkeys (Macaca mulatta) at the Nanwan peninsula of Hainan Island, China, have been observed in the field for 25 years, and have been studied intensively for eight years, beginning in 1981. There were about 115 monkeys in 5 natural groups when the Nanwan Reserve was founded in 1965. From 1965 to 1984, the number of groups increased from 5 to 19, and the total population increased from 115 to 930 individuals, an annual population increase of 12.7%. From 1984 to 1987, the population continued a slower rate of increase (8.9%) to approximately 1200 monkeys in 20 groups. The home ranges of each monkey group at Nanwan varied from 0.16 to 0.72 km², with a mean and standard deviation of 0.37 ± 0.18. The size of the home range of the rhesus was affected by the quality of vegetation and rhesus population density. The average birth rate per year was 77.8 ± 13.9%, varying from 53.8% to 100% since 1978. From 1978, the birth rates of two food provisioned groups were higher in alternate years (x? = 91.7%) and lower in intervening years (x? = 68.8%; P = <0.01). A minority (26.5%) of females have given birth at 4 years of age, most at 5 years. The sex ratio of newborns in any one year varied from 0.3 to 3.5 males to females, with a mean and standard error of 1.09 ± 0.37 males to females.     

An integrative mating system assessment of a nonmodel,economically important Pacific rockfish (Sebastes melanops) reveals nonterritorial polygamy and conservation implications for a large species flock

Characterizing the mating systems of long‐lived, economically important Pacific rockfishes comprising the viviparous Sebastes species flock is crucial for their conservation. However, direct assignment of mating success to sires is precluded by open, offshore populations and high female fecundity. We addressed this challenge by integrating paternity‐assigned mating success of females with the adult sex ratio (ASR) of the population, male evolutionary responses to receptive females, and reproductive life history traits—in the framework of sexual selection theory—to assess the mating system of Sebastes melanops. Microsatellite parentage analysis of 17 pregnant females, 1,256 of their progeny, and 106 adults from the population yielded one to four sires per brood, a mean of two sires, and a female mate frequency distribution with a truncated normal (random) pattern. The 11 multiple paternity broods all contained higher median allele richness than the six single paternity broods (Wilcoxon test: W = 0, p < .001), despite similar levels of average heterozygosity. By sampling sperm and alleles from different males, polyandrous females gain opportunities to enhance their sperm supply and to lower the cost of mating with genetically incompatible males through reproductive compensation. A mean of two mates per mated female with a variance of one, an ASR = 1.2 females per male, and the expected population mean of 2.4 mates for mated males (and the estimated 35 unavailable sires), fits polygamous male mate frequency distributions that distinguish polygynandry and polyandrogyny mating systems, that is, variations of polygamy, but not polyandry. Inference for polygamy is consistent with weak premating sexual selection on males, expected in mid‐water, schooling S. melanops, owing to polyandrous mating, moderately aggregated receptive females, an even ASR, and no territories and nests used for reproduction. Each of these characteristics facilitates more mating males and erodes conspicuous sexual dimorphism. Evaluation of male evolutionary responses of demersal congeners that express reproductively territorial behavior revealed they have more potential mechanisms for producing premating sexual selection, greater variation in reproductive success, and a reduced breeding effective population size of adults and annual effective size of a cohort, compared to S. melanops modeled with two mates per adult. Such divergence in behavior and mating system by territorial species may differentially lower their per capita birth rates, subsequent population growth, and slow their recovery from exploitation.     

Operational Sex Ratio and Individual Mating Frequencies in Two Bushcricket Species (Orthoptera,Tettigonioidea, Poecilimon)

During mating the male bushericket transfers a large spermatophore which is consumed by the female after copulation. Such a ‘nuptial gift' is likely to have strong effects on the mating frequency of both males and females and thus on the operational sex ratio (OSR): For the male a longer time period will be required in which he is prevented from further matings. For the female consumption may be advantageous increasing interest in matings. To quantify these effects field studies were carried out on two species of the genus Poecilimon. Both species differed widely in the mean number of matings observed per day (19% of all females in P. veluchianus compaied to 42% in P. affinis; Fig. 2) and thus in the distribution of female mating intervals (P. veluchianus 2 days, P. affinis 1 day (modes); Fig. 3). Separate experiments on the minimum male mating interval and the spermatophore weight also revealed distinct differences: the mean spermatophore weight was 26% of the male body weight in P. veluchianus and 15% in P. affinis (Fig. 6). Accordingly the refractory period was longer in P. veluchianus; 3 days after a previous mating nearh all males were ready to remate, compared to 2 days in P. affinis (Fig. 5). These differences, however, compensated one another in that the amount of spermatophylax material transferred per day was very similar in both species in relation to female body weight. Using data on female mating frequency per day and male remating ability, an upper estimate for the OSR was calculated. A lower limit for the OSR was given taking into account the most frequent female mating interval (big. 7). In both species the OSR remained relatively constant for large parts of the season. The medians (upper/lower estimate for the ratio males to females ready to mate: 2.95/1.19 in P. veluchianus; 2.22 0.88 in P. affinis) were very low, comparable to that in explosive breeding frog species. Thus in the bushcricket mating system, females may be able to demand large male mating efforts so that the operational sex ratio can come close to unity.     

Thermal acclimation in the grain miteAcarus siro (Acari: Acaridae)

Grain mites reared on wheat germ at 21±1°C and 85% r.h. were treated (acclimated) as adults at 0, 14, 28 or 33°C for 1 or 4 days. Fecundity, longevity and numbers of F₁ females and males produced were compared. A treatment of 1 day was enough to acclimateAcarus siro and change the studied developmental parameters. Acclimation always lowered fecundity but the magnitude of the effect was dependent upon the temperature regime. The number of males and females emerging differed greatly among various temperature regimes; however, the sex ratio of emerged adults remained in most instances quite constant.     

Spatial organisation and dynamics of the pine marten Martes martes population in Białowieza Forest (E Poland) compared with other European woodlands

We studied factors affecting density and spacing patterns in the pine marten Martes martes population inhabiting temperate forests of Bia?owieza National Park, eastern Poland. From 1985/1986 to 1995/1996 marten densities ranged from 3.63 to 7.57 individuals 10 km^?2 (mean 5.4) and were positively correlated with abundance of forest rodents in the previous year. The rate of marten population growth was inversely density‐dependent and positively related to rodent density. Annual mortality rate averaged 0.384 and tended to be negatively related to marten densities. Mean annual home range of males (2.58 km², SE=0.24) was larger than that of females (1.41 km², SE=0.20). Seasonal home ranges also differed significantly between males and females. Both sexes held the smallest ranges in December–January. Female ranges increased in April–May, whereas those of males increased in June–September when they were mating. Fidelity of pine martens to their home ranges was very high. The mean shift between arithmetic centres of seasonal ranges was 0.25 km, and the ranges recorded in two consecutive seasons overlapped, on average, by 87–90%. We observed very little home range overlap between neighbouring male (mean 4–6%) or female (mean 6%) marten. Year round the neighbouring individuals of the same sex neither avoided nor attracted each other. Females attracted males only during the spring‐summer mating season. A review of other studies has documented that winter severity and seasonal variation in ecosystem productivity were essential factors shaping the biogeographic variation in pine marten densities between 41^o and 68^oN. The density of marten populations increased in areas with mild winters and lower seasonality. Maximum population densities (indicative of habitat carrying capacity) were correlated with mean winter temperature. In Europe, male home ranges increased with decreasing forest cover in a study area, whereas female ranges varied positively with rodent abundance.