Population dynamics and phenology of two congeneric and sympatric lynx spiders Peucetia rubrolineata Keyserling, 1877 and Peucetia flava Keyserling, 1877 (Oxyopidae)

Numerous phenological studies on spiders belonging to the families Oxyopidae, Thomisidae, Lycosidae, Selenopidae (e.g. Selenops cocheleti) and Salticidae (e.g. Psecas chapoda and Psecas viridipurpureus) have been conducted in the neotropical region. However, studies that simultaneously compare population dynamics and age structure in populations of sympatric species are limited, especially in Oxyopidae. The population dynamics and phenology of two congeneric lynx spider (Peucetia rubrolineata and Peucetia flava) were examined in southeastern Brazil. Several characteristics of the age structure were compared between the two spider species. The variation in the total abundance of individuals and age structure and their relationship with climatic variables were similar between the two spiders. Adults of these spiders were present mainly in spring, indicating an annual reproductive cycle and a ‘stenochronous spring’ phenological pattern. The recruitment of spiders occurred in summer for P. rubrolineata and P. flava, followed by successive phenological peaks at all stages of development. Rainfall and temperature had a positive correlation to population flux in the two spider species studied. Despite the significant climatic effects observed in the Serra do Japi, the phenological pattern of the population in this study was not always repeated in other species of spiders (e.g. Selenops cocheleti).     

Seasonal cycle of zooplankton abundance and biomass in Hamsilos Bay,Sinop, Southern Black Sea,Turkey

In this investigation, zooplankton was studied between July 2015 and June 2016 in Hamsilos Bay to examine spatial and temporal variations in abundance, biomass and taxonomic composition. The recorded mean zooplankton abundance and biomass were 3770.35 ind. m^?3 and 25.06 mg m^?3 in the inner station, 3928.11 ind. m^?3 and 28.19 mg m^?3 in the middle station and 3948.22 ind. m^?3 and 28.74 mg m^?3 in the outer station, respectively. The high abundance and biomass values observed in September 2015 were attributed to Oithona davisae (4575 ind. m^?3 at the inner station) and Penilia avirostris (33.4 mg m^?3 at the outer station), respectively. Copepoda was the most abundant during the entire period of the survey. In terms of abundance and biomass, Copepoda was followed by meroplankton and Cladocera. Most species within the zooplankton community exhibited evident seasonality throughout the year in Hamsilos Bay. This was particularly apparent for O. davisae, Centropages ponticus, Cladocera and meroplankton, which were abundant in summer–autumn, and for Pseudocalanus elongatus, which was more abundant during winter and spring. It has been determined that O. davisae, which is a non-indigenous cyclopoid copepod species of the Black Sea, has successfully inhabited southern Black Sea and has established a permanent population in this area.     

Population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) in the northern Aegean Sea (NE Mediterranean)

The population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) were studied in the northern Aegean Sea in samples collected annually (1997–2000) in summer, through experimental trawl, at depths down to 600 m. Females were larger than males in Plesionika martia and Plesionika heterocarpus; no significant differences in size of males and females were found in Chlorotocus crassicornis and Plesionika antigai. A trend of increasing size with depth was observed, as well as a linear increase in the proportion of females with increasing size. Sex ratio was skewed towards females at all depths in P. antigai, while in P. heterocarpus and C. crassicornis males dominated the intermediate depths. Negative allometries were apparent in the carapace length–weight relationships in males of all species. Isometric relationships were found in females apart from in P. heterocarpus. The population patterns conform to relevant Mediterranean reports. However, some population differences exist that may reflect the distinct environmental conditions prevailing in the study area.     

Early life history of the sheepnose (Plethobasus cyphyus) (Mollusca: Bivalvia: Unionoida)

Managing a rare species can be improved with knowledge of its natural history. The sheepnose (Plethobasus cyphyus) is a freshwater mussel recently listed by the US as federally endangered. We used standard methods to study P. cyphyus brooding behaviour, host fishes in the laboratory and under natural conditions, and glochidial morphology. We monitored a population of P. cyphyus in the Chippewa River, WI during spring and summer 2007–2009 and 2011 and found brooding animals between mid-May and early August. Gravid individuals ranged between 5 and 27 yr (mean age ± 1 s.d. = 13 ± 4 yr). Plethobasus cyphyus brooded glochidia in outer gills, which varied in colour from red, orange, pink, cream, or white. We observed mature glochidia more commonly in individuals with cream or white gills and these glochidia were released in a clear, adhesive, mucus matrix. In laboratory trials we found several minnow and topminnow species (29 spp.) served as productive suitable native hosts. The mean number of juvenile mussels released per cyprinid per day was significantly higher for trials conducted at 22–25°C compared with those at 18–20°C, and 83% of trials conducted at 18–20°C using suitable host species produced no juveniles. Glochidia had a unique outline and shell morphometrics that distinguished P. cyphyus from seven other Chippewa River mussel species that produce similar sized glochidia. Using morphometrics we determined that mimic shiners (Notropis volucellus) were natural hosts for P. cyphyus, round pigtoe (Pleurobema sintoxia), and Wabash pigtoe (Fusconaia flava). Releasing mucus-bound glochidia has evolved in a variety of mussel species and may be more common than is currently realized. Our data show that P. cyphyus is a cyprinid host specialist, and propagation efforts for this species can be strengthened through improved access to mature glochidia by using females with cream-coloured gills and increased juvenile production through warmer fish holding temperatures.     

Seasonal abundance and life cycle of Archaeomysis articulata (Crustacea: Mysidacea) on a sandy beach of western Hokkaido,Japan

Abundance and life cycle of the sandy beach mysid Archaeomysis articulata Hanamura were investigated based on seasonal collections over 2 years in the surf-swept intertidal zone of an open sandy beach in Ishikari Bay, western Hokkaido, Japan. The number of mysids in the intertidal zone increased from winter to spring, reaching its maximum in summer to autumn (average >2500 ind. m^-2), and decreased considerably towards the end of the year. The abundance was maintained at a minimal level (<200 ind. m^-2) throughout the winter. The breeding season was March to November, during which the liberation of young was most intensive from late April to mid-October. Three alternate generations, including overwintering, spring and summer generations, were suggested from field observations. Archaeomysis articulata is primarily iteroparous; only a restricted number of breeding females could produce more than two broods. The life span was estimated to be 7–9 months for the overwintering generation and 2.5–3.5 months for the spring–summer generations. The sex ratio fluctuated at samplings, with a tendency toward female dominance (overall mean=54%). The number of embryos carried by a single female ranged from 16 to 94, tending to increase with increasing size of females. The size of egg-like embryos varied seasonally from 0.45 to 0.54mm, being largest in spring and smallest in summer, with no correlation to the length of females; water temperature is considered an important factor in regulating the size of eggs. The embryonic development time was estimated to be 1.5 months for the spring generation (water temperature 5–10°C), and much shorter than this for the summer and overwintering generations. The mortality rate during embryonic development was estimated to be 7–18%.     

Mating behaviour and maternal care in the tropical savanna funnel-web spider Aglaoctenus lagotis Holmberg (Araneae: Lycosidae)

Despite their abundance and diversity, Neotropical spiders have been the subject of relatively few studies of behavioural ecology. The sexual behaviour and maternal care of the spider Aglaoctenus lagotis (Lycosidae) is described here. We performed experimental manipulations to test the hypothesis that males are attracted by female cues in the web. Two predictions were tested: (a) webs used by a virgin female will attract more males than webs used by an inseminated female; (b) the main cue in the web is chemical, so webs recently used by virgin females will attract more males than those that are not recently used. Additionally, we tested the hypothesis that maternal care increases offspring survivorship. Results showed that males are attracted by recently used webs (z = 0.0015; p = 0.037; z-test) and webs of virgin females (z = 0.041; p = 0.036, z-test). Male sexual behaviour presented three different categories: court, pre-mate and mate. After the mating, the females built a cocoon that was transported adhered to the spinnerets and held by the last pair of legs. After the hatching of the eggs, the young migrated to the dorsal region of the mother's body for 5 days. During maternal care the mother eliminates a yellowish drop from its oral cavity, which is collected by the young. During the development of the young until adulthood, the offspring that have their mother present in the first stages of life have greater survival compared with those without maternal care. Our results make it possible to perform comparative analyses between a South American Lycosidae species and other species distributed worldwide.     

Relating abundance of purpleback flying squid Sthenoteuthis oualaniensis (Cephalopoda: Ommastrephidae) to environmental parameters using GIS and GAM in south-eastern Arabian Sea

The distribution pattern of purpleback flying squid and the relationship between its abundance and environmental variables in the south-eastern Arabian Sea were analysed using a geographical information system (GIS) and a generalised additive model (GAM). Highest abundances were observed during December and January within 10 and 13°N and 71 and 72°E around the Lakshadweep Islands. The mean abundance in the area was 4.21 tonnes/km² and the maximum sustainable yield (MSY) was estimated as 0.63 million tonnes. GAM indicated that very high squid abundance was associated with low values of dissolved oxygen (6.01–6.27 mg/L), sea surface temperature (28.03–28.62°C), pH (7.75–8.56), salinity (30.42–34.48 psu), chlorophyll-a (0.4–0.6 mg/m³), zooplankton biomass (0.23–0.64 mL/m³), and shallow 20°C isotherm (101.2–134.7 m) and mixed layer depth (17.8–29.8 m). As a carnivore from paralarval stages, S. oualaniensis depends on secondary and tertiary production to sustain its population for which primary production is used up. In the tropical Arabian Sea where temperature differences are not so pronounced, S. oualaniensis distribution was found to be related to a low but very narrow sea surface temperature (SST) band. There is sufficient fishable biomass in the area to possibly launch a new targeted oceanic squid fishery from the western seaboard of India.     

Reproductive ecology of the glass frog Espadarana prosoblepon (Anura: Centrolenidae) in an urban forest of the Central Andes of Colombia

Population and reproductive behaviour aspects of the glass frog Espadarana prosoblepon are well known for populations from Central America, but similar information is lacking for populations from South America. We recorded the reproductive ecology of a population of the glass frog E. prosoblepon in the city of Armenia, Central Andes of Colombia. With weekly surveys with mark-recapture between December 2013 and November 2015, we monitored activity patterns and evaluated if the probability of males mating is associated to their body size or to chorus tenure (i.e. the number of nights a same individual is calling for attracting a mate). In addition, upon observing an amplexus, we recorded the behaviour of the individuals until oviposition and noted characteristics of egg clutch. We recorded 47 males and 32 females, nine amplexus events, eight ovipositions, and 21 egg clutches (35.4 ± 4.79 eggs per clutch, N = 29). Activity of males and females and the number of egg clutches were positively correlated to rainfall. Mating success of males was not associated to their body size, but it was positively associated to longer chorus tenure; clutches from large females had a higher number of eggs than clutches from small females. Oviposition occurred on average 3.76 ± 1.74 hours after we first observed the amplexus, occurring 93.1% of the time in fronds of Selaginella geniculata at an average height of 1.58 ± 0.44 m. After the oviposition, the male left the site, while the female remained between 30 and 45 min, partially covering the eggs. The reproductive behaviour of E. prosoblepon did not vary widely between a population in Costa Rica and our population in time to oviposition, and mating success of males associated to chorus tenure; however, in our study population we recorded a larger clutch size and the preference for S. geniculata fronds as oviposition substrate.     

Nesting territory characteristics of a migratory South American forest hawk,the White-throated Hawk (Buteo albigula) (Aves: Accipitridae), in temperate rainforest remnants of Araucanía,southern Chile

During four successive breeding periods (2007–11) we characterized the nesting territories of the white-throated hawk (Buteo albigula) in southern Chile. Territories were located in mountainous areas with mature native forest (n = 17) or mature pine plantations (n = 1). Most of the territories were distant from urban centres (>2 km). Only one or two adult hawks and one young per pair/year were observed in each territory. All nest sites were located in the upper parts of ravines. Nests were built on large, living mature trees. Platforms were bulky (>50 cm diameter) and oval or round. Eggs were white and subelliptical in shape (40.0 × 50.0 mm). Hawk pairs reproduced asynchronically extending the reproductive period for 6 months. Although some white-throated hawk pairs were tolerant of human-modified habitats, it is possible that decline in forest cover represents a potential threat for the population viability of this migratory forest hawk.     

Demographic characteristics,seasonal range and habitat topography of Balkan chamois population in its southernmost limit of its distribution (Giona mountain,Greece)

The annual range of Balkan chamois (Rupicapra rupicapra balcanica) in Giona mountain was found to be 5502 ha, with a low population density (2 individuals/100 ha). Seasonal range patterns varied significantly, with a minimum extent in summer and a maximum in winter (30% and 79% of the annual range, respectively). Summer stress and the rutting period might be associated with the observed aggregated distributions during the summer and autumn (core areas of 28% and 22% of seasonal ranges, respectively, defined after the Fixed Kernel Density Estimator). Chamois were found to use significantly lower altitude habitats in winter (1212 m) than in summer (2223 m), and significantly steeper slopes in winter (35°); aspect was not found to have a significant effect on habitat use. Population structure consisted of kids (21%), yearlings (8%), females (35%) and males (36%). Conservation management for the species should consider poaching, livestock competition and global warming.     

Life history of Paraselenis (Spaethiechoma) dichroa (Germar, 1824) (Coleoptera: Chrysomelidae: Cassidinae) in natural conditions of Atlantic Forest from Brazil

Cassidinae Gyllenhaal? is the second largest subfamily of Chrysomelidae (Coleoptera), which presents characteristic morphology, biology and behaviour. The current study describes the life cycle of Paraselenis(Spaetiechoma) dichroa (Germar), ?determining biological and behavioural aspects as well as the action of natural enemies on populations, when the species has maternal care. The study was conducted between February and April 2015 in the National Forest of Passa Quatro, municipality of Passa Quatro, Minas Gerais state, Brazil. Daily observations were made (morning and afternoon) to evaluate the offspring of females on Ipomoea sp. and Merremia macrocalyx (O’Donell?) (Convolvulaceae), as well as the actions of natural enemies on the young. The eggs are deposited on the midrib and abaxial surface of leaves (n = 25). Egg clusters are pedunculated, arranged in groups and devoid of any cover. On average, each female produced 27.3 ± 5.6 (n = 16) eggs, with a mean incubation period of 12.7 ± 2.9 days (n = 10 females with their young). The larvae remained grouped in the leaves throughout development, except when they fed. They retained faeces and exuviae as a stacked faecal structure on their mobile urogomphi (caudal process) like a faecal shield. The mean number of larvae per female was 12.7 ± 10.1 (n = 19) and the larval period lasted 24.9 ± 4.5 days (n = 12). Pupation occurred on the stem of the plant (n = 16). On average there were 8.1 ± 8.5 individuals for pupae progeny (n = 14). The mean duration of the pupal stage was 10.4 ± 3.3 days (n = 5). Overall, 3% of adults emerged (n = 13 individuals), with a total cycle time of 41.3 ± 8.4 days (n = 6). Adults are sexually dimorphic in the elytral shape. Females remain with the offspring throughout development. The natural enemies of immatures were Emersonella pubipennis Hansson? (Hymenoptera: Eulophidae), Tachinidae (Diptera) and Stiretrus decastigmus (Herrich-Schaeffer?) (Heteroptera: Pentatomidae), Conura sp. Spinola? (Hymenoptera: Chalcididae) and Brachymeria sp. Westwood? (Hymenoptera: Chalcididae). The information presented here on the natural history of P. dichroa are important as they may serve as a starting point to understand evolutionary questions and multispecies interactions.     

Investigating the influence of habitat type and weather conditions on the population dynamics of land snails Vertigo angustior Jeffreys, 1830 and Vertigo moulinsiana (Dupuy, 1849). A case study from western Poland

The conservation of land snails has become an urgent issue because of the current global decline of this group. Detailed knowledge of population dynamics is needed to develop an appropriate strategy for conservation. We investigated the population dynamics of two threatened European land snail species: Vertigo angustior and Vertigo moulinsiana. Although the species may be found at the same site, V. moulinsiana is more tolerant of wetter conditions than is V. angustior. Abundance data for the two species were collected at two sites (one drier and one wetter) in western Poland biweekly during the spring and summer months in 2008 and 2009. In the drier year, snail abundance was similar between the drier and wetter sites. In the wetter year, snail abundances were generally higher than in the dry year, except that the inundation-intolerant V. angustior became less abundant at the wetter site. We conclude that weather affects different species differently and therefore should be considered along with the habitat features in interpreting survey results for land snails.     

Reproductive strategies of two sympatric species of Hyalella Smith, 1874 (Amphipoda,Dogielinotidae) in laboratory conditions

This study was performed in order to test theoretical predictions that sympatric species might show different reproductive strategies to facilitate their coexistence. The duration of precopulatory mate‐guarding behaviour, body size of ovigerous females, embryonic and postembryonic development time, fecundity, and viability of the sympatric amphipod species Hyalella pleoacuta and H. castroi were investigated under laboratory conditions (19±1°C and 12 h light/dark photoperiod). Specimens were collected with nets in autumn and spring 2004, and summer and winter 2005 in the Vale das Trutas, São José dos Ausentes County, southern Brazil, and transported to the laboratory. Both species of Hyalella showed similar reproductive strategies, especially in respect to the duration of the precopula, duration of the embryonic period, and fecundity. However, these species differed in body size of ovigerous females, duration of the postembryonic period, viability, and body size of juveniles that remained in the marsupium and those released by females. These differences in the reproductive traits of H. pleoacuta and H. castroi may facilitate their coexistence in nature.     

Population dynamics of the gall inducer Eriogallococcus isaias (Hemiptera: Coccoidea: Eriococcidae) on Pseudobombax grandiflorum (Malvaceae)

Eriogallococcus isaias Hodgson and Magalhães is a Neotropical species of gall-inducing scale insect (Coccoidea: Eriococcidae), whose phenological synchrony with its host plant, Pseudobombax grandiflorum, is fundamental to the maintenance of its population. Furthermore, E. isaias is unusual among gall-inducing Eriococcidae because its galls are not sexually dimorphic and are induced by the second-instar nymphs. We studied the life cycles of the host plant and the galling insect, and followed the development of the insects and the structure of the gall. The results showed that gall induction is synchronous with leaf flushing, and that the galls and leaves mature concomitantly. Males have a 36–48-day life cycle within the gall, whereas females have a 75–100-day life cycle.     

Breeding biology of the threatened Campo Miner Geositta poeciloptera (Aves: Scleruridae), a Neotropical grassland specialist

The Campo Miner is a threatened grassland passerine endemic to the South American Cerrado, whose life history is almost unknown. In this paper, we studied during three breeding seasons (2014 to 2016) the breeding biology of a colour banded population of the species found in the Upper Rio Grande Grasslands, south-eastern Brazil. We found 98 nests, 81 of which became active and were monitored. The Campo Miner breeds in frequently burnt-and-grazed natural grasslands, successfully nesting in highly disturbed sites, such as dirt banks along roads and even in mine pits. The species is socially monogamous and both parents build the nest, which is a cavity/with-tunnel/simple/platform type. The nest chamber is lined with a platform made of grass fragments, charcoal, hairs, and mammal faeces. The most common clutch size is three eggs (n = 66), with some nests containing one (n = 1), two (n = 12) or four eggs (n = 2). The egg is white and pyriform and the incubation, performed by both parents, lasts 17.5 days. Mean nestling period is 15.5 days, with both parents feeding the young. Breeding season lasted for about 125 days (August to December) and multiple breeding attempts in a single season were common, with a maximum of three attempts recorded. All species of Scleruridae built their nests inside cavities dug in the soil with an access tunnel to it, where they lay a small clutch (usually 2–3 white eggs), but no other species in the family has been studied in detail to date. Further studies are required to understand why a species apparently tolerant to anthropogenic impacts such as G. poeciloptera can be so rare, patchily distributed and threatened throughout its range.     

Population dynamics of the bark-dwelling spider Eustala perfida Mello-Leitão, 1947 (Araneidae)

Population dynamics of spiders may vary according to biotic and abiotic factors. We studied the phenology of the bark-dwelling spider Eustala perfida over a two-year period and investigated how temperature, precipitation, and prey availability were associated with the population of this species. The population of E. perfida presented a well-defined fluctuation, with one reproductive cycle per year. The recruitment of spiders occurred in summer, followed by successive phenological peaks at all stages of development. The species is protogynic, and the population of adult males peaks in the cold/dry season, indicating a winter mature phenological pattern. The diet of E. perfida is composed mainly of medium-sized homopterans, complemented by small dipterans and hymenopterans. We found that the higher abundance of spiders occurred two months after the highest values of precipitation and temperature, and three months after the higher abundance of potential prey items. These results indicate that spiders require time to respond to changes in environmental conditions. The species’ natural history and the structure of the trunks in which it lives may also affect the number of individuals in a particular area and over time.     

Using short-term surveys and mark–recapture to estimate diversity and population size of orchid bees in forest formations of the Brazilian savanna

Studies on the diversity and population dynamics of euglossine bees in forest formations of the Brazilian savanna can be notably informative considering that most species are forest-dependent. The current study aimed to estimate the diversity and population size of euglossine bees using short-term surveys and the mark–recapture method. We also compared short-term surveys with monthly surveys over a 1-year period (long-term surveys) to assess the species diversity. The study occurred in seven forest formations of the Brazilian savanna. We collected 14 species and marked 375 males but recaptured only 23 (6.1%). The population size of Euglossa bees ranged from 111.1 ± 34.4 to 1384.5 ± 384.6 males. The diversity indices achieved through the short-term surveys were similar to or higher than those obtained from long-term studies. The low recapture rate of euglossine males seems to be the result of their long-distance dispersal capacity. We also proposed that short-term surveys be viewed as a favourable alternative to long-term studies on diversity estimation and that euglossine bees can occur in small populations in some forest formations studied.     

The first vertebrate fossil from Socotra Island (Yemen) is an early Holocene Egyptian fruit bat

Data on the prehistoric biota of the Socotra Archipelago (Yemen) are scarce. We report on the first extinct vertebrate ever recorded from this western Indian Ocean island group. An exceptionally preserved adult specimen of Egyptian fruit bat Rousettus aegyptiacus was found in a calcite flowstone in Hoq Cave on the NE coast of Socotra Island. Accelerator mass spectrometry (AMS) radiocarbon dating on bone fragments estimates the fossil at ca. 7600–7400 cal a BP (radiocarbon age 6669 ± 70 ¹⁴C a BP) corresponding to an early Holocene wet period in southern Arabia and the Horn of Africa. Morphometric analysis of the skull compared to Recent specimens from the neighbouring mainlands finds the fossil morphologically most similar to Egyptian (Nile Valley and Libyan Desert), not to East African or Middle Eastern populations. The species is currently absent from the Horn of Africa (Somalia and Eastern Ethiopia). Although potentially a stray individual, we also discuss the palaeoenvironmental implications under the hypothetical scenario that the fruit bat is a remnant of an extinct resident population. If so, the extinction of an important pollinator and seed disperser may have impacted the Socotran terrestrial ecosystems.