The natural history of a monogamous coral-reef fish, Valenciennea strigata (Gobiidae): 2. behavior, mate fidelity and reproductive success

This study examined the behavior and reproduction of a monogamous coral-reef fish, Valenciennea strigata, to determine mate fidelity and the proximate causes of monogamy. Most fish were found in monogamous pairs that remained together over several rounds of reproduction. Pairs stayed within close proximity to each other and their burrows. Females fed at a higher rate than their mates, while males spent more time maintaining burrows. Females spawned every 13 days; males guarded eggs in the burrow for 2–3 days. Although females limited the RS of males, males did not mate polygynously under natural conditions. Reproductive success (RS) was affected primarily by survival, and secondarily by size. Both sexes enforced monogamy by guarding their mates. Three factors facilitated mate guarding: (1) all males were able to hold a nest site, (2) both sexes showed strong site fidelity, and (3) residents had an advantage in contests over mates. Thus, mates were economically defensible. Additionally, females formed a crescent of dark pigments on their abdomen that resembled a gravid condition; these marks may enhance continuation of the pair bond. Both sexes preferred large mates, and pairs were positively assorted by size. Males benefited from guarding large females because fecundity increased with size. Females may benefit from the burrowing of males, and larger males should be better burrowers.     

Long-term demographics of a coral-reef fish: growth,survival and abundance at several spatial scales

Coral Reefs - In marine organisms, pelagic larval dispersal often results in genetic panmixis among widely separated populations; however, local conditions may produce populations of marine...     

The influence of turbidity on growth and survival of fish larvae: a numerical analysis

Growth and survival through the early larval phase probably limit the production potential of many commercially important fish stocks. Attempts to increase the production of these stocks by restocking of juveniles have generally failed. Here, we analyse how enhanced concentrations of phytoplankton and zooplankton affect the survival of fish larvae during their early life stages. The analysis is developed for larvae feeding on copepod eggs and nauplii, with fish and invertebrates as major predators. A model of feeding and growth of fish larvae is applied to assess the benefit of enhanced phytoplankton and zooplankton abundance. The analysis shows that the shading effect of higher phytoplankton concentration may reduce predation rates on fish larvae substantially. This `top-down' effect may be more important for the cohort survivorship than the `bottom-up' mechanism in situations when larval food is sufficiently abundant. However, while increased algal biomass will improve recruitment at high zooplankton concentration, it may also reduce recruitment at low zooplankton concentrations and shallow mixing depths. Both the larvae and their vertebrate predators are dependent on light to detect their prey, and the longer reactive distance of the predators make them more susceptible than the larvae to reduced light levels and increased turbidity. We discuss the implications of reduced predation and increased zooplankton abundance on recruitment and production of fish larvae, and point at environmental conditions where changing algal biomass is likely to affect recruitment success.     

Recruitment and growth of two small‐bodied resident fish species (Gobiidae and Atherinidae) in oligohaline,seasonally open lagoons

Spatio‐temporal recruitment patterns, growth and survival of the Swan River goby Pseudogobius olorum and western hardyhead Leptatherina wallacei are described from two small, coastal lagoons on the south coast of Western Australia. In these lagoons, estuarine salinity dynamics were relatively stable over much of the autumn–spring period when freshwater inputs from rivers were reduced and there was no oceanic connection. Preflexion and flexion stages of both fish species contributed strongly to population size structure in downstream reaches, whereas upstream reaches were dominated by postflexion larvae and juvenile stages. Spawning of both species was protracted and largely asynchronous, although the episodic presence of stronger preflexion and flexion cohorts suggested some synchronized spawning had occurred. Comparison with estuarine conditions over this period provided evidence that synchronized spawning may be related to temperature and salinity variations from a combination of freshwater inputs and periods of marine exchange. Uninterrupted growth and the progression of cohorts through to juvenile stages were consistent with the generally stable estuarine conditions. Larval and juvenile stages of both species were also tolerant of abrupt changes in salinity and temperature, which occurred due to a non‐seasonal oceanic connection. These findings were consistent with the euryhaline nature of adults of both species.     

The function of mate guarding in a field cricket (Orthoptera: Gryllidae;Teleogryllus natalensis otte and cade)

Three hypotheses relating to the function of postcopulatory mate guarding were tested for the cricketTeleogryllus natalensis. The hypothesis that guarding allows the male to remain with the female for repeated matings was rejected. This was because the mean intercopulatory interval for maleT. natalensis was found to be nearly twice as long as the mean duration of guarding. Nor do the results provide evidence to support the hypothesis that guarding functions to prevent copulation attempts by rival males (the rival exclusion hypothesis): the presence of a rival male was found to have no significant effect on the duration of spermatophore attachment for either guarded or unguarded females. The results do, however, support a third hypothesis, namely, that guarding functions to prevent the female from removing the spermatophore ampulla before complete sperm transfer. As predicted by this hypothesis, the presence of a guarding male was found to have a significant positive effect on the duration of spermatophore attachment. Further support for this hypothesis was provided by the fact that there was a significant positive correlation between the duration of mate guarding and the duration of spermatophore attachment.     

The life cycle, population dynamics, growth and secondary production of the snail Xeropicta arenosa Ziegler (Gastropoda: Pulmonata) in northern Greece

The life cycle, population dynamics and secondary production of the xerothermophilic land snail Xeropicta arenosa were studied in northern Greece. The study of biology and the demographic analysis of the populations of X. arenosa revealed that it is a semelparous annual species. Reproduction takes place in autumn and the majority of the adults die after egglaying. Growth is continuous throughout the year and no seasonal fluctuations occur. Estimation of annual secondary production with the Hynes' size frequency method revealed a mean standing crop ( aa ) of 0.075 g m^-2 year^-1 and a productivity ( P ) of 0.267+ 0.043 gm^-2 year^-1. The annual turnover ratio ( P/ ) was equal to 3.56.     

The variability of mating signals and preferences in the brown planthopper,Nilaparvata lugens (Homoptera: Delphacidae)

Male and female brown planthoppers, Nilaparvata lugens(Stål) (Homoptera: Delphacidae), exchange substrate-transmitted signals prior to mating. The pulse repetition frequency of the male song is known to be involved in mate recognition and also to vary among geographical populations. Here the variability of male signals, female signals, and female preferences has been examined within a population. Female preference variation has been partitioned into variation in mean preference and variation in the window of preference of individuals. The genetic component of variation has been examined using isofemale lines. Male signal variation was limited (CV=8%) and was mainly within individuals. Female signal variation was greater (CV=15%). Female mean preference varied little (CV=10%) and was closely matched to the male signal mean, but the preference window was wide (> 4 male signal standard deviations on average) and variable (CV=56%). There was evidence for genetic variation only for preference window. These results are discussed in relation to theories of signal system evolution.     

The natural history of the sleepy lizard,Tiliqua rugosa (Gray, 1825) – Insight from chance observations and long‐term research on a common Australian skink species

In an effort to better understand the dynamics of the parapatric boundary in South Australia of the ticks Amblyomma limbatum and Bothriocroton hydrosauri the late Professor C. Michael Bull initiated studies into the ecology of sleepy lizards (Tiliqua rugosa), a common host of these parasites. These studies spanned a period of about 40 years and examined aspects such as monogamy, long‐term mate fidelity, social networks, personality, resource use and the transmission of parasites and other pathogens. This review incorporates the results of these studies with other information about this species to provide a comprehensive overview of its natural history, highlighting not only what is known, but also indicates areas that require further study.     

The effects of temperature and body size on the mating pattern of a gregariously nesting bee, Colletes cunicularius (Hymenoptera: Colletidae)

Abstract. 1. In a 3-year study of the solitary bee Colletes cunicularius L. in Sweden, average body size and population density fluctuated greatly between years.
2. In this protandrous population, females mated just once and the sex ratio was slightly male biased. Males were smaller than females.
3. Size assortative mating (homogamy), associated with an increase in population density during the central days of female emergence and mating, was observed in two out of three years. Homogamy was also observed in pairs with remating males.
4. Most of the mating males had emerged the day they mated, but 42% were older. We found no support for a general large-male mating advantage.
5. Weight of emerging females and mating males were negatively correlated with ground temperature, indicating thermoregulatory influence on the process of sexual selection in this species.     

The flexible lek: Phymatopus hecta the gold swift demonstrates the evolution of leking and male swarming via a hotspot (Lepidoptera: Hepialidae)

Leking moths present an evolutionary problem in their apparently simultaneous reversal of male–female attraction. The mating system of Phymatopus (or Hepialus) hecta embraces an unusually wide range of procedures. Both males and females use medium‐range olfactory attractants (also probably visual signals), and both sexes will lure, and both will approach, the other, either when flying or perched. This produces an ‘infinite variety’ which includes the classic moth mating procedure (males fly to sessile female); a typical lek procedure (female flies to sessile male); a mating swarm (hovering male follows passing female); and intermediates such as a mutual courtship dance. Male behaviour includes a flying display, two sessile displays, and an escalating war of attrition. The system is versatile, persistent, and probably evolutionarily stable. The lek site has a high density of perches suitable for copulation which facilitate predator‐escape by means of a dead drop. The whole supports a model for the evolution of resource‐based leks which commence with a concentration of females on a hotspot, leading to a concentration of males; and then an escalating process of sexual selection as males become increasingly attractive over a distance to females, and females use the males as a way of locating the resource. The main stabilizing pressure may be selection for efficient mate acquisition, and as with grouse leking systems, the precondition for evolution was probably having travelling females that actively sought a reproductive resource or a predator free space. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 184–201.     

Behaviour, natural history, and annual cycle of the Henderson Island rail Porzana atra (Aves: Rallidae)

The little known endemic Henderson Island rail (or Henderson rail) Porzflna atra , inhabits forest on the coastal plain and upraised plateau of Henderson Island. Rails were studied for 15 months from January 1991 to March 1992. The population was estimated at c. 6200 individuals living in pairs or cooperative groups of 3–4 adults on territories averaging about 1 ha. Two or three eggs were laid in covered or open nests near the ground from mid-July to mid-February. Up to five consecutive nesting attempts were made in cases where eggs or young chicks were lost. Adults laid a second clutch when chicks were fully feathered at about one month of age. Both sexes incubated and helped rear the young. Older chicks sometimes helped feed younger siblings. Dispersal of juveniles from the natal territory took place in April. Adult birds underwent a rapid, simultaneous post-nuptial moult of the remiges in February-April; the post-juvenile moult involved body feathers only. Data on morphometries, breeding ecology, courtship behaviour and voice are compared with available information for the spotless crake P. tabuensis , the Henderson rail's closest relative and probable ancestor. These comparisons provide some information on how these two taxa have differentiated since rails arrived on Henderson Island some time in the last 380000 years.     

The impact of extensive clonal growth on fine-scale mating patterns: a full paternity analysis of a lily-of-the-valley population (Convallaria majalis)

Background and Aims

The combination of clonality and a mating system promoting outcrossing is considered advantageous because outcrossing avoids the fitness costs of selfing within clones (geitonogamy) while clonality assures local persistence and increases floral display. The spatial spread of genetically identical plants (ramets) may, however, also decrease paternal diversity (the number of sires fertilizing a given dam) and fertility, particularly towards the centre of large clumped clones. This study aimed to quantify the impact of extensive clonal growth on fine-scale paternity patterns in a population of the allogamous Convallaria majalis.

Methods

A full analysis of paternity was performed by genotyping all flowering individuals and all viable seeds produced during a single season using AFLP. Mating patterns were examined and the spatial position of ramets was related to the extent of multiple paternity, fruiting success and seed production.

Key Results

The overall outcrossing rate was high (91 %) and pollen flow into the population was considerable (27 %). Despite extensive clonal growth, multiple paternity was relatively common (the fraction of siblings sharing the same father was 0·53 within ramets). The diversity of offspring collected from reproductive ramets surrounded by genetically identical inflorescences was as high as among offspring collected from ramets surrounded by distinct genets. There was no significant relationship between the similarity of the pollen load received by two ramets and the distance between them. Neither the distance of ramets with respect to distinct genets nor the distance to the genet centre significantly affected fruiting success or seed production.

Conclusions

Random mating and considerable pollen inflow most probably implied that pollen dispersal distances were sufficiently high to mitigate local mate scarcity despite extensive clonal spread. The data provide no evidence for the intrusion of clonal growth on fine-scale plant mating patterns.     

Population dynamics of an endangered heathland shrub,Epacris stuartii (Epacridaceae): Recruitment,establishment and survival

The only known population of the endangered shrub Epacris stuartii Stapf was studied from 1994 to 2001 using demographic census techniques. The effects of substrate, a fire and a storm on the emergence and survival of seedlings and the survival of established plants of different sizes were examined using failure‐time analyses and logit‐linear models. Ninety‐five per cent of seedling emergence was delayed until the second post‐fire spring, an unusual response among species with persistent soil seed banks. Mortality of seedlings was extreme compared with larger‐seeded species, but diminished significantly with age. Seedling mortality varied significantly between substrates: 40% of seedlings persisted for more than 5 years in mineral soil, whereas less than 10% lived more than a year on rock and intermediate substrates. However, seedling numbers and local densities were lower on soils than other substrates. Background mortality of established plants was lower on soil and intermediate substrates (0.5% per year) than on rock (3% per year). Small plants may be more susceptible than large plants on rock, but not on soil. Both the fire and the storm resulted in elevated mortality of established plants. The population exhibited a variable response to fire, with plants on rock and intermediate substrates behaving as obligate seeders, whereas plants in soil resprouted. This appears to be the first report of microhabitat variation in fire response at sympatric scales. The effects of the storm were apparently independent of substrate and plant size. The essentially independent disturbance regimes comprising recurring fires and storms are likely to have a profound effect on the long‐term population dynamics of E. stuartii. Over the 7‐year census period, recruitment has failed to compensate for mortality, resulting in a 30% net decline in the population. The demographic census has proved to be crucial in the detection and diagnosis of this decline.     

Emergence, Mating, and Postmating Behaviors of the Oriental Beetle (Coleoptera: Scarabaeidae)

In a previous field-trapping study of the oriental beetle, Exomala orientalis (Waterhouse), by using synthetic sex pheromone on golf course fairways, numerous males were observed and trapped during the hours of peak mating activity. However, very few beetles were observed in the same areas when synthetic pheromone was absent. To investigate the hypothesis that mating in nature occurs cryptically within vegetation at the soil surface, laboratory studies on female emergence and pheromone release, male emergence and mate-locating, and female and male mating behaviors were conducted. Mate acquisition and copulation occurred on the soil surface near the female emergence site, with both sexes engaging in pheromone-mediated behaviors after having emerged from the soil. A highly stereotyped female pheromone release, or calling, behavior was observed, consisting of insertion of the female's head into the soil and elevation of the tip of her abdomen into the air. Bioassays conducted in a wind tunnel that simulated a turf fairway environment showed that walking and flying were both important in the upwind response of males to females. Mating and copulation occurred without an obvious complex courtship, but observations of postmating behaviors suggested that mate guarding occurs.     

Spatial relationships between mate acquisition probability and aggregation size in a gregarious coreid bug, (Colpula lativentris): A case of the ideal free distribution under perceptual constraints

Spatial relationships of mate acquisition probability for individuals of both sexes of a gregariously-mating coreid bug, Colpula lativentris, were studied in relation to aggregation size. Operational sex ratio was always strongly male biased. Mate acquisition probability of females was rather constant and independent of aggregation size, as predicted by an ideal free distribution. Moreover laboratory experiments showed that both multiple mating and rearing density little affected female fecundity, suggesting ideal free distribution of females in terms of reproductive success. On the other hand, mate acquisition probability of males was higher in larger aggregations, where more receptive females were available. This male discrepancy from an ideal free distribution was similar to the patterns predicted by an ideal free distribution under perceptual constraints (Abrahams, 1986), but not by that under unequal competitive ability.     

The natural history, thermal physiology, and ecological impacts of intertidal mesopredators, Oedoparena spp. (Diptera: Dryomyzidae)

Abstract. The ecological roles of small (1–1000 mg) predators in benthic marine systems are poorly understood. We investigated the natural history and predatory impact of one group of such mesopredators—larvae of dipteran flies in the genus Oedoparena —which prey on intertidal barnacles. We 1) quantified patterns of larval Oedoparena distribution and abundance in the Northwest Straits of Washington State, USA, 2) determined larval physiological tolerance limits in the laboratory, and 3) conducted a manipulative field experiment to assess the role of microhabitat temperature on predation rates in Oedoparena . Members of Oedoparena in Washington are univoltine, with peak larval abundance in late spring and early summer. Infestation frequencies in the barnacles Balanus glandula and Chthamalus dalli were as high as 22% and 35%, respectively. In laboratory studies, larvae of O . glauca were able to tolerate temperatures up to 37°C; however, this temperature is often exceeded in high intertidal habitats. In a field manipulation using experimental shades, we demonstrate that the alleviation of physiological stress greatly increased the abundance of larvae of Oedoparena spp. As a result of increased larval densities under shades, adult B. glandula mortality increased from 5% to nearly 30%, and C. dalli mortality increased from less than 20% to over 60%. Because high intertidal barnacles serve as food and habitat for a diverse array of species, Oedoparena spp. have the potential to play a major role in structuring high intertidal communities, particularly in cooler microhabitats.     

The effects of harvesting of the South African kelp (Ecklonia maxima) on kelp population structure, growth rate and recruitment

Ecklonia maxima is an economically important kelp in South Africa. The harvested kelp is used mainly as feed for cultured Haliotis midae (abalone) on farms all along the South African South and West Coast. The effects that different harvesting methods have on the growth of sub-canopy kelps, kelp population structure and kelp recruitment were tested in a kelp bed at Bordjies Rif near Cape Town. Two 30 × 10 m sites were set up, about 100 m apart, in near monoculture stands of E. maxima. Each 30×10 m area was subdivided into three treatments. In treatment 1 (T1) the whole ‘head’ of each kelp sporophyte that reached the surface was cut off between the bulb and the primary blade (‘lethal’ method). In treatment 2 (T2) (‘non-lethal’ method), the secondary fronds of all sporophytes that reached the surface were cut 20–30 cm from their junction with the primary blade, and removed. In the control plot, the kelp plants were not treated. Harvesting treatments were done approximately every four months, at low spring tide, from 3 March 2003 to 3 November 2003 (three treatments). The effects of harvesting on the kelps depend largely on the size of plant and the time the fronds were removed; however, no seasonal pattern could be observed. The different treatments had no effect on the growth rate, population structure or recruitment of the kelp. This means that factors other than light play an important role in the growth, structure and recruitment of the kelp beds in False Bay. Results are discussed in relation to current commercial harvesting practices.     

Inter- and intraspecific differences in the life history and growth of Caridina spp. (Decapoda: Atyidae) in Hong Kong streams

1. The life‐history pattern of three populations of Caridina cantonensis (Atyidae) and one population of Caridina serrata were studied in four Hong Kong streams: Pak Ngau Shek (PNS), Kap Man Hang (KMH), Pak Tam Chung (PTC), and Lung Fu Shan (LFS). Caridina cantonensis occurred at PNS, KMH and PTC while C. serrata was present at LFS only. Monthly quantitative sampling was carried out at each study site over 2 years to investigate life‐history patterns and cohort‐specific growth rates. 2. Breeding by both species was mainly restricted to the wet season, and there was an increase in the incidence of ovigerous females as water temperatures rose at the start of the summer monsoon. The number of cohorts and the frequency of recruitment of C. cantonensis (one to three times each year) were highly site‐specific, but consistent between years. 3. Shrimp growth was size‐dependent, and decreased with increasing body size. Caridina cantonensis at PTC had the highest cohort‐specific growth rates (0.05–0.14 mg ash‐free dry weight (AFDW) mg^?1 day^?1), followed by C. serrata at LFS (6% lower), and C. cantonensis at KMH and PNS (16–39% lower). Shrimp life spans exceeded 1 year (17–22 months), depending on site and species. 4. Sexual maturity occurred at an earlier age and at a smaller size in populations with higher growth rates. Shrimps at PTC and LFS matured at approximately 4 months old; this was 3 months earlier than at KMH and 5 months earlier than at PNS. Females of C. cantonensis at PTC and C. serrata at LFS may have bred twice during each breeding season, while females in the other two populations bred once only. The number of cohorts produced by each population in each year did not vary between the years of the study. Most sexually mature individuals only survived long enough (for 10–12 months after maturation) to breed during one season. 5. The mean brood size of C. cantonensis varied among streams and was 25–28% larger at PNS and KMH than at PTC. Egg size did not differ among populations. Larger brood sizes at PNS and KMH may have been a consequence of increased availability of algal food in these unshaded stream sites. Caridina serrata had similar egg and brood sizes to C. cantonensis, but females were smaller and reproductive investment was higher. Thus, the degree of intraspecific variation in atyid breeding in Hong Kong was at least equal to, if not greater than, the extent of interspecific variation. Interspecific differences in life history may reflect the frequency of droughts and spate intensity experienced by C. serrata at LFS.     

The memory of water: Archaeobotanical evidence of wetland plants from Modena (Emilia-Romagna,northern Italy) and palaeoecological remarks

Modena, founded by the Romans (183 BC), has always been conditioned by water in all its urban history. In the city, numerous archaeobotanical investigations have been carried out in order to reconstruct the natural landscape and human–environment interactions over time. During these investigations, four archaeological sites (two Roman and two medieval) have revealed deposits with a marked character of palaeobiocoenosis, largely resulting from the natural environment surrounding the sites, due to natural “seed rain”. These deposits are characterized by widespread evidence of plants related to water, constituting a valuable archive to investigate habitats which currently have become very rare and threatened, if they have not completely disappeared. The present paper aims to reveal the peculiarities of the Roman/medieval archaeocarpological floristic lists (through a comparison with the flora over the last two centuries in the area of Modena) and highlight the possible causes explaining the presence or the demise of several taxa, considering also the palaeoecological reconstruction of the environment in which they have been found.