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The study of nocturnally active bats is difficult even for those species that seasonally congregate. This challenge is particularly acute for 'ope'ape'a (Hawaiian hoary bat; Lasiurus semotus) because of its solitary foliage-roosting behavior. Yet surveys are essential for conservation and management of this endangered species and only land mammal endemic to the Hawaiian Islands. We surveyed for 'ope'ape'a at 23 sites and a range of elevations (33-2,341 m) on Hawai'i Island from May 2018 to August 2021. We captured 138 unique bats (37 female, 101 male) over 224 mist-netting events. We averaged 16 net-hours per bat capture, with peak captures 30-90 min after sunset. We marked all captured individuals in this study with identifying forearm bands and recaptures represented 7% of total captures (10 of 148). We developed generalized linear mixed models to examine the relationship of nightly bat captures by sex to elevation and time-of-year while accounting for variable sampling effort and repeated sampling in this study. Both males and females were captured at low and high elevations with peak capture rates occurring at approximately 930 m. The capture rate for females was highest during the reproductive season (May to September), whereas it was highest for males during the non-reproductive season (October to April). This study informs future fieldwork with a description of 'ope'ape'a capture on Hawai'i Island by sex, elevation, time-of-year and time-of-night, radio transmitter retention, and recapture frequency. Keywords: Hawaiian hoary bat, 'ope'ape'a, Lasiurus semotus, Hawai'i, mist-net capture, VESPER BATS (FAMILY VESPERTILIONIDAE) are relatively small and primarily nocturnal, making it difficult to evaluate distribution, abundance, and population trends (Carter et al. 2003). One approach common to bat studies [...]

Unlike most cephalopods, the firefly squid Watasenia scintillans is highly monoandrous. We investigated this unusual phenomenon by considering the rare occurrence of polyandrous mating and the extremely male-biased operational sex ratio (OSR) at the beginning of the mating season. Theoretically, male-biased OSR can intensify competition for mates, leading to increased polyandry. We estimated OSR (male/female) as 32.7 and 9.1 at the beginning and end of the mating period, respectively. Next, we estimated the rate of polyandry in a population on a weekly basis, based on our new finding that the rate of polyandry can be estimated stochastically from the total number of spermatangia attached to one of the two seminal receptacles within a female. We found that the female squid sustains their highly monoandrous mating regime despite the fact that the OSR is extremely male-biased. Furthermore, there were no significant changes in the polyandry rate during the reproductive season. These results suggest that the squid mating system was not influenced by seasonal changes in OSR. Here, we discuss the evolutionary mechanism of how monoandry persists in this species., Author(s): Md. Nur E. Alam [sup.1] , Noritaka Hirohashi [sup.1] Author Affiliations: (1) grid.411621.1, 0000 0000 8661 1590, Graduate School of Natural Science and Technology, Shimane University, , Matsue, Japan [...]

We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona, and Pseudocalanus, we estimate that predation mortality contributed [greater than or equal to] 69% of the field mortality rate in adult males, whereas in Acartia, Oithona, and Calanus adult females, this is [greater than or equal to] 36%. We conclude that (1) adult sex ratio skew in pelagic copepods is primarily due to differential mortality of the sexes in the adult stage and not in juveniles, (2) mortality rates of adult Acartia, Pseudocalanus, and Oithona are dominated by predation mortality rather than physiological longevity (except under extreme food limitation), and (3) in Pseudocalanus and Oithona, elevated mortality rates in adult males to females is predominantly due to higher predation on males. Our work demonstrates that we now need to develop a more comprehensive understanding of the importance of feeding preferences in predators. doi: 10.4319/lo.2010.55.5.2193

The proximity of mates can influence mating opportunities and the quantity and quality of offspring, especially in dioecious plant species. Progeny sex ratios modulated by environmental conditions is one of the most radical ways in which offspring quality may be influenced, yet it has rarely been reported in plants. A mechanism proposed to influence progeny sex ratios in dioecious plants involves competition between female- and male-determining microgametophytes (certation) as a result of variation in pollination intensity. However, the role of selective fertilization in dioecious plants is controversial and has not been demonstrated under field conditions. Here we investigate whether natural variation in the spatial arrangement of females and males influences pollination intensity and progeny sex ratios in the wind-pollinated herb Rumex nivalis. Based on previous experimental manipulation of pollination intensity in this species, we predicted that maternal parents in close proximity to males would produce more strongly female-biased progeny sex ratios. We tested this prediction in six alpine populations in Switzerland by measuring the distance between focal females and neighboring males and assessing pollen loads and seed sex ratios of maternal parents. In four of the six populations, females positioned in close proximity to males captured more pollen and exhibited more female-biased sex ratios. Our results demonstrate that demographic aspects of the maternal mating environment can influence progeny sex ratios. The most probable explanation for biased primary sex ratios in Rumex is selective fertilization resulting from pollen tube competition. female-biased sex ratios | pollination intensity | selective fertilization

Abstract: Rubus chamaemorus L. is a dioecious clonal herb with highly variable fruit production. Our overall objective was to determine how fruit production (and the reproductive stages leading to fruit) [...]

Alpine ibex (Capra ibex) are polygynous ungulates that exhibit extreme sexual dimorphism and segregation. To test the hypothesis that risk of predation plays a key role in the development of sexual segregation (habitat segregation) in this species, compositions and locations of groups of ibex were recorded from February 2003 to October 2004. Individual fixes of marked adult males and females in the Gran Paradiso National Park in Italy were collected monthly over a 4-year period (January 2000--December 2003). Distances were measured between each location and the nearest refuge area (rocky slopes), and between each location and the nearest source of disturbance (roads and hiking trails). Group size was not related to distances from refuge areas or from sources of disturbance, but sex, age, and weaning played a key role in spatial segregation. During the period of rut, females kept nearer to rocky slopes and further from hiking trails than males. The presence of young also influenced the spatial behavior of females: mothers made use of refuge areas more frequently and of areas near hiking trails less frequently than other females. In contrast, no difference between the spatial behaviors of pregnant and nonpregnant females was recorded in spring. Age played an important role in space use by males, but not by females. Young males (2-5 years) stayed closer to rocks than did middle-aged males (6-11 years), and both stayed closer to rocks than did adult males (> 11 years). Adult males stayed closer to hiking trails than middle-aged males; likewise, the latter stayed closer to hiking trails than young males. Males stayed near areas with human presence, likely because of good foraging opportunities. Although our findings do not exclude other explanations, they support the reproductive strategy-predation risk hypothesis. Moreover, predation risk was shown as an important factor leading to both sexual and age segregation in males. Key words: alpine ibex, antipredator behavior, Capra ibex, predation risk, sexual segregation