Reproductive Coordination in a Nonseasonally Breeding Primate Species,Macaca silenus

Varying types of reproductive coordination among females have been described for several mammals. Among nonhuman primates, female reproductive coordination has usually been described as breeding seasonality, or in few cases, closer synchrony within the breeding or birth season. We examined birth records from a large captive colony of lion-tailed macaques, Macaca silenus, a nonseasonally breeding species, in order to determine the degree of female reproductive synchrony in this population. Births were nonrandomly distributed over the 10-year study period. Of the total of 28 births, the majority (21 or 75 %) of births occurred in cohorts, in spite of wide variations in interbirth intervals among cohort birth mothers. Cohorts consisted of two to five infants born within a 90-d period or less. Of the remaining 7 “isolated” births, four were in the three years in which only one or two births occurred. The pattern of cohort births was nonrandomly distributed according to mother's parity: three of the isolated births were to primiparous mothers, whereas only one of the 21 cohort births was to a primiparous mother. Estrous synchrony results showed that females in the longer-established of two groups exhibited greater synchrony, suggesting social facilitation of reproductive coordination. It is thus suggested that synchrony in this sample was the result of social rather than ecological mechanisms, as has been hypothesized for some other mammalian species.     

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.     

A Sub-population of Group A Streptococcus Elicits a Population-wide Production of Bacteriocins to Establish Dominance in the Host

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Parasitic Nematode Abundance Aggregation as a Mechanism of the Adaptive Response of the Host Plant to Temperature Variations

The mathematical model of host–parasite relations suggested previously by the authors was applied to analyze the formation of the aggregated distribution of parasites in the case of the host plant–parasitic nematode system. For nearly the same conditions and empirical infection levels, nematode abundances in the host population followed the gamma distribution. Exposure to temperature stresses modifies the resistance of the plant population to infection. Experiments with prolonged chilling of potato plants prior to nematode infestation revealed no statistically reliable increase in the share of resistant plants compared to the control, although the mean and the range of variation of the infection rate, as well as the aggregation of the parasite distribution, decreased. Short-term chilling of the plants prior to infestation led to a reliable decrease in the mean abundance of parasites and to the lowest aggregation of the parasitic nematode in the host plant population. The results of this study showed that this temperature stress caused potatoes to develop a reliably high and uniform resistance to the nematode.     

Responses of Salt Marsh Plant Rhizosphere Diazotroph Assemblages to Changes in Marsh Elevation,Edaphic Conditions and Plant Host Species

An important source of new nitrogen in salt marsh ecosystems is microbial diazotrophy (nitrogen fixation). The diazotroph assemblages associated with the rhizospheres (sediment directly affected by the roots) of salt marsh plants are highly diverse, somewhat stable, and consist mainly of novel organisms. In Crab Haul Creek Basin, North Inlet, SC, the distribution of plant types into discrete zones is dictated by relatively minor differences in marsh elevation and it was hypothesized that the biotic and abiotic properties of the plant zones would also dictate the composition of the rhizosphere diazotroph assemblages. Over a period of 1 year, rhizosphere sediments were collected from monotypic stands of the black needlerush, Juncus roemerianus, the common pickleweed, Salicornia virginica, the short and tall growth forms of the smooth cordgrass Spartina alterniflora, and a mixed zone of co-occurring S. virginica and short form, S. alterniflora. DNA was extracted, purified and nifH sequences PCR amplified for denaturing gradient gel electrophoresis (DGGE) analysis to determine the composition of the diazotroph assemblages. The diazotroph assemblages were strongly influenced by season, abiotic environmental parameters and plant host. Sediment chemistry and nitrogen fixation activity were also significantly influenced by seasonal changes. DGGE bands that significantly affected seasonal and zone specific clustering were identified and most of these sequences were from novel diazotrophs, unaffiliated with any previously described organisms. At least one third of the recovered nifH sequences were from a diverse assemblage of Chlorobia, and γ-, α-, β- and δ-Proteobacteria. Diazotrophs that occurred throughout the growing season and among all zones (frequently detected) were also mostly novel. These significant sequences indicated that diazotrophs driving the structure of the assemblages were diverse, versatile, and some were ubiquitous while others were seasonally responsive. Several ubiquitous sequences were closely related to sequences of actively N₂ fixing diazotrophs previously recovered from this system. These sequences from ubiquitous and versatile organisms likely indicate the diazotrophs in these rhizosphere assemblages that significantly contribute to ecosystem function.     

Interactions of Fire and Nonnative Species Across an Elevation/Plant Community Gradient in Hawaii Volcanoes National Park

Invasive species interacting with fires pose a relatively unknown, but potentially serious, threat to the tropical forests of Hawaii. Fires may create conditions that facilitate species invasions, but the degree to which this occurs in different tropical plant communities has not been quantified. We documented the survival and establishment of plant species for 2 yr following 2003 wildfires in tropical moist and wet forest life zones in Hawaii Volcanoes National Park, Hawaii. Fires were ignited by lava flows and burned across a steep environmental gradient encompassing two previously burned shrub-dominated communities and three Metrosideros polymorpha forest communities. Fires in all community types were stand replacing, where >95 percent of overstory trees were top killed. Over half (>57%) of the trees survived via basal sprouting, but sprout growth differed among forest communities. Sprout growth (>250,000 cm³) was greatest in the forest community where postfire understory cover was lowest presumably due to thick native Dicranopteris linearis fern litter that remained postfire. In contrast, M. polymorpha sprout growth was much slower (<100,000 cm³) in the two forest communities where there was rapid understory recovery of nonnative ferns Nephrolepis multiflora and invasive grasses Paspalum conjugatum. These results suggest that the rapid establishment of an invasive-dominated understory limited recovery of the overstory dominant M. polymorpha. In contrast to the three forest communities, there were few changes in vegetation composition in the shrubland communities. Nonnative species invasions coupled with repeated fires selectively eliminated fire-sensitive species thereby maintaining these communities in dominance of primarily nonnative, fire-resilient, species.     

Fluctuations in Populations of 3 Vorticella Species from an Activated-Sludge Sewage Plant

SYNOPSIS. To evaluate Vorticella populations in an activated sludge sewage-disposal plant as a ) indicators and b ) contributors to purification, population behavior in the plant was compared with behavior in clonaI cultures maintained with mixed sludge microflora. In a 12-month survey of protozoa in the plant, of 37 spp recorded only 9—all ciliates—were indigenous. Ciliate populations fluctuated cyclically. Alternations in dominance of Vorticella convallaria (L.) with V. octava (Stokes) + V. aequitata (Kahl) apparently followed changes in bacterial activity as indicated by changes in reduction of biochemical oxygen demand and suspended solids of the wastes. This correlation of Vorticella and bacterial activities was also investigated with clonal populations of the vorticellas and their accompanying mixed microflora—the bacteria being isolated together with the vorticellas from sludge samples. The mixed microflora which consistently supported healthy vorticellas was predominantly proteolytic. Varying periods of dominance in Vorticella species thus indicated activity of their supporting microflora. Log-phase bacteria activity stimulated V. octava ; stationary and declining phases stimulated V. convallaria. Thus, V. octava appeared predatory and V. convallaria appeared to require bacterial conditioning of the medium. Bacterial activity was stimulated by V. octava predation. Vorticella activity may thus promote purification.     

Host Plant Resistance as an Alternative to Methyl Bromide for Managing Meloidogyne incognita in Pepper

Pre-plant soil fumigation with methyl bromide and host resistance were compared for managing the southern root-knot nematode (Meloidogyne incognita) in pepper. Three pepper cultivars (Carolina Cayenne, Keystone Resistant Giant, and California Wonder) that differed in resistance to M. incognita were grown in field plots that had been fumigated with methyl bromide (98% CH₃Br : 2% CCl₃NO₂ [w/w]) before planting or left untreated. Carolina Cayenne is a well-adapted cayenne-type pepper that is highly resistant to M. incognita. The bell-type peppers Keystone Resistant Giant and California Wonder are intermediate to susceptible and susceptible, respectively. None of the cultivars exhibited root galling in the methyl bromide fumigated plots and nematode reproduction was minimal (<250 eggs/g fresh root), indicating that the fumigation treatment was highly effective in controlling M. incognita. Root galling of Carolina Cayenne and nematode reproduction were minimal, and fruit yields were not reduced in the untreated plots. The root-galling reaction for Keystone Resistant Giant was intermediate (gall index = 2.9, on a scale of 1 to 5), and nematode reproduction was moderately high. However, yields of Keystone Resistant Giant were not reduced in untreated plots. Root galling was severe (gall index = 4.3) on susceptible California Wonder, nematode reproduction was high, and fruit yields were reduced (P ≤ 0.05) in untreated plots. The resistance exhibited by Carolina Cayenne and Keystone Resistant Giant provides an alternative to methyl bromide for reducing yield losses by southern root-knot nematodes in pepper. The high level of resistance of Carolina Cayenne also suppresses population densities of M. incognita.     

Interspecific Variation in the Reproductive Response of Acacia Species to Protection from Large Mammalian Herbivores

We quantified the fruit set of four Acacia spp. inside and outside of long-term experimental exclosures in order to examine the fitness consequences of herbivory by large mammals. We found a considerable interspecific variation in the reproductive fitness costs of herbivory in four African Acacia spp. Acacia nilotica and A. brevispica respond to protection from large mammalian herbivores by greatly increasing their seed set. In contrast, there was little or no increase in seed set in A. mellifera and A. etbaica . The reasons for these differences are not known, but may be related to armament morphologies.     

Can a Threshold Value Be Used to Classify Chondrichthyan Reproductive Modes: Systematic Review and Validation Using an Oviparous Species

The maternal-embryonic nutritional relationship in chondrichthyans has been poorly explored. Consequently, accurately discerning between their different reproductive modes is difficult; especially lecithotrophy and incipient histotrophy. This present study is the first to assess changes in mass throughout embryonic development of an oviparous chondrichthyan other than Scyliorhinus canicula. Heterodontus portusjacksoni egg cases were collected and used to quantify the gain or loss of wet mass, dry mass, water content, inorganic and organic matter from freshly deposited eggs (without macroscopically visible embryos) to near full-term embryos. A loss in organic mass of ∼40% found from this study is approximately double the values previously obtained for S. canicula. This raises concerns for the validity of the current threshold value used to discern between lecithotrophic and matrotrophic species. Accordingly, 26 studies published in the primary literature between 1932 and 2012 addressing the maternal-embryonic nutritional relationship in sharks were reviewed. Values for changes in mass reported for over 20 different shark species were synthesised and recalculated, revealing multiple typographical, transcribing, calculation and rounding errors across many papers. These results suggest that the current threshold value of −20% established by previous studies is invalid and should be avoided to ascertain the reproductive mode of aplacental viviparous species.     

Vocal Mimicry of Alarm‐Associated Sounds by a Drongo Elicits Flee and Mobbing Responses from Other Species that Participate in Mixed‐Species Bird Flocks

A growing number of studies have shown that vocal mimicry appears to be adaptive for some bird species, although the exact function of this behaviour varies among species. Previous work has looked at the function of the vocal mimicry of non‐alarm sounds by the Greater Racket‐tailed Drongo (Dicurus paradiseus). But drongos also imitate sounds associated with danger, such as predators' vocalisations or the mobbing‐specific vocalisations of other prey species, raising the question of whether the function of mimicry can vary even within a species. In a playback experiment, we compared the effect on other species of different drongo vocalisations including: (1) predator mimicry, (2) mobbing mimicry, (3) drongo species‐specific alarms, (4) drongo species‐specific non‐alarms and (5) a control (barbet) sound. Both mobbing mimicry and drongo species‐specific alarms elicited flee responses from the most numerous species in the flocks, the Orange‐billed Babbler (Turdoides rufescens). Mobbing mimicry also elicited mobbing responses from the Orange‐billed Babbler and from another gregarious babbler, the Ashy‐headed Laughingthrush (Garrulax cinereifrons); when responses from both species were considered together, they were elicited at a significantly higher level by mobbing mimicry than by the barbet control, and a level that tended to be higher (0.07 < p < 0.10) than the response to drongo‐specific alarms. Predator mimicry elicited flee and mobbing responses at an intermediary level. Our results support the hypotheses that mobbing mimicry is a specific category of mimicry that helps attract the aid of heterospecifics during mobbing and that alarm mimicry can in some cases be beneficial to the caller.     

Physiological Responses of Three Contrasting Plant Species to Groundwater Level Changes in an Arid Environment

Plants growing on both sides of the Tarim River in western China serve as a natural barrier containing the deserts and protecting the oasis, and their growth is greatly affected by water conditions In their local habitat. We studied the physiological responses of three different types plants （i.e. Populus euphratlca Oliver, Tamarix ramosissima L., and Apocynum venetumas Linn） to changing groundwater levels by analyzing changes in chlorophyll, soluble sugar, proline （Pro）, malondialdehyde （MDA）, superoxlde dlsmutase （SOD）, peroxidase （POD）, indoleacetic acid （IAA）, giberellic acid, abscisic acid （ABA） and cytokinin （CK）. Relationships between these physiological characteristics and groundwater levels were analyzed in order to assess the drought tolerance of the three plant species based on the values of average membership function. We found that MDA, SOD and ABA were more susceptible to changes in groundwater level, followed by POD, IAA and CK. Among the three plant species, Populus euphratica responded physiologically less to changing groundwater level than T. ramosissima and A. venetumas.     

A Phosphate Transporter from the Root Endophytic Fungus Piriformospora indica Plays a Role in Phosphate Transport to the Host Plant

Because pure cultures and a stable transformation system are not available for arbuscular mycorrhizal fungi, the role of their phosphate transporters for the symbiotic interaction with the plant up till now could not be studied. Here we report the cloning and the functional analysis of a gene encoding a phosphate transporter (PiPT) from the root endophytic fungus Piriformospora indica, which can be grown axenically. The PiPT polypeptide belongs to the major facilitator superfamily. Homology modeling reveals that PiPT exhibits twelve transmembrane helices divided into two halves connected by a large hydrophilic loop in the middle. The function of the protein encoded by PiPT was confirmed by complementation of a yeast phosphate transporter mutant. The kinetic analysis of PiPT (K_m 25 μm) reveals that it belongs to the high affinity phosphate transporter family (Pht1). Expression of PiPT was localized to the external hyphae of P. indica colonized with maize plant root, which suggests that external hyphae are the initial site of phosphate uptake from the soil. To understand the physiological role of PiPT, knockdown transformants of the gene were prepared using electroporation and RNA interference. Knockdown transformants transported a significantly lower amount of phosphate to the host plant than wild-type P. indica. Higher amounts of phosphate were found in plants colonized with wild-type P. indica than that of non-colonized and plants colonized with knockdown PiPT P. indica. These observations suggest that PiPT is actively involved in the phosphate transportation and, in turn, P. indica helps improve the nutritional status of the host plant.     

Livestock Diversification: an Adaptive Strategy to Climate and Rangeland Ecosystem Changes in Southern Ethiopia

Pastoral cattle production in southern Ethiopia is becoming increasingly vulnerable to impacts of climate variability and rangeland resource degradation, giving rise to livestock diversification. Using a household (n?=?242) survey among herders, the relative functions, adaptability and vulnerability of four livestock species and factors influencing livestock diversification were analyzed. The stated major drivers of livestock diversification were recurrent droughts, bush encroachment, increased vulnerability of cattle and growing demand for adaptive species. Different livestock species are kept to fulfill various livelihood priorities with subsistence objectives outweighing production goals of the herders. Adaptability and vulnerability analyses of the livestock species showed camels and cattle to be the most and least adaptable species, respectively. Livestock species diversification varied significantly with family size and per capita holding of cattle, implicating the influence of labor and economic factors on adoptions. Multispecies herding emerged as the dominant local adaptation strategy, likely because it enhances resilience of households to climate and rangeland ecosystem changes by broadening the set of existing strategies.     

Dark Leaf Respiration in Light and Darkness of an Evergreen and a Deciduous Plant Species

Dark respiration in light as well as in dark was estimated for attached leaves of an evergreen (Heteromeles arbutifolia Ait.) and a deciduous (Lepechinia fragans Greene) shrub species using an open gas-exchange system. Dark respiration in light was estimated by the Laisk method. Respiration rates in the dark were always higher than in the light, indicating that light inhibited respiration in both species. The rates of respiration in the dark were higher in the leaves of the deciduous species than in the evergreen species. However, there were no significant differences in respiration rates in light between the species. Thus, the degree of inhibition of respiration by light was greater in the deciduous species (62%) than in the evergreen species (51%). Respiration in both the light and darkness decreased with increasing leaf age. However, because respiration in the light decreased faster with leaf age than respiration in darkness, the degree of inhibition of respiration by light increased with leaf age (from 36% in the youngest leaves to 81% in the mature leaves). This suggests that the rate of dark respiration in the light is related to the rate of biosynthetic processes. Dark respiration in the light decreased with increasing light intensity. Respiration both in the light and in the dark was dependent on leaf temperature. We concluded that respiration in light and respiration in darkness are tightly coupled, with variation in respiration in darkness accounting for more than 60% of the variation in respiration in light. Care must be taken when the relation between respiration in light and respiration in darkness is studied, because the relation varies with species, leaf age, and light intensity.     

Brood Parasitism in Two Species of Spider Wasps (Hymenoptera: Pompilidae, Dipogon), with Notes on a Novel Reproductive Strategy

A trap-nesting study provided the first documentation of brood parasitism in Dipogon nagasei and in D. iwatai. Dipogon nagasei was found to brood parasitize D. sperconsus, D. conspersus, D. inconspersus, and D. bifasciatus. Dipogon iwatai brood parasitized D. sperconsus, D. conspersus, D. romankovae, and Auplopus carbonarius. Both brood parasitic species are with the subgenus Nipponodipogon, whereas all five Dipogon hosts are in the subgenus Deuteragenia. Comparison of their ecological features revealed that brood parasitism in D. nagasei is considerably more derived than in D. iwatai. Of particular note is the fact that in D. nagasei the female routinely lays up to five eggs on a single host spider, all of which develop into adult wasps without larval cannibalism; almost all Pompilidae previously studied lay only one egg on a host spider.     

The Role of Adaptation to Host Plants in the Evolution of Reproductive Isolation: Negative Evidence from Tetranychus Urticae Koch

Reproductive isolation between demes of a phytophagous arthropod population that use different host plant species could evolve in two different ways. First, adaptation to different host species might result in reproductive isolation as a pleiotropic by-product. Second, if adaptation to one host species strongly reduces fitness on others, selection could favour mechanisms, such as host fidelity and assortative mating, that restrict gene flow between host-adapted demes. A laboratory selection experiment on the broadly polyphagous spider mite Tetranychus urticae gave information on these possibilities. A population allowed to adapt to tomato plants showed increased survival, development rate and fecundity on tomato relative to the base population from which it was derived. In spite of the large difference between the tomato-adapted and base populations in performance on tomato plants, the two populations showed no evidence of reproductive isolation, as measured by the hatching rate of eggs laid by F1 hybrids between the lines. Furthermore, a genetically variable population formed by hybridizing the tomato-adapted and base populations did not show evidence for a decline in ability to survive on tomato after more than ten generations of mass rearing on lima bean, indicating that tomato-adapted genotypes suffered little or no selective disadvantage on bean. These results give no support for the role of host plants in the evolution of reproductive isolation in T. urticae.     

Behavioral and Physiological Aspects of Reproductive Control in a Diacamma Species from Malaysia (Formicidae,Ponerinae)

The reproductive system of a Diacamma species from Malaysia is described. Intact colonies have no queens. Instead one mated worker (gamergate) reproduces. Only a few workers (2%) have weakly developed ovaries. Newly emerged workers possess thoracic appendages, called gemmae, but only one worker retains them, mates and becomes a gamergate. All other individuals are mutilated mostly by already mutilated workers. After the gamergate has been removed this mutilation-behavior continues for at least 24 h. After three days no more mutilation occurs. Groups of workers without gamergate start to fight about one week after the gamergate was removed and one worker reaches the alpha-position and becomes the sole egg layer. When workers emerge in already established groups they are not mutilated. Workers, which were isolated one week earlier than the rest of the group, and thus already escaped inhibition by the gamergate, had a higher chance to obtain the alpha-position. To test factors that might influence worker-dominance, juvenile hormone titer was measured. Juvenile hormone was not detectable in gamergates and alpha-workers but the amounts of juvenile hormone in non-reproductive workers increased with age. This is discussed with regard to the situation found in honeybees.     

Variation in Butterfly Larval Acoustics as a Strategy to Infiltrate and Exploit Host Ant Colony Resources

About 10,000 arthropods live as ants'' social parasites and have evolved a number of mechanisms allowing them to penetrate and survive inside the ant nests. Many of them can intercept and manipulate their host communication systems. This is particularly important for butterflies of the genus Maculinea, which spend the majority of their lifecycle inside Myrmica ant nests. Once in the colony, caterpillars of Maculinea “predatory species” directly feed on the ant larvae, while those of “cuckoo species” are fed primarily by attendance workers, by trophallaxis. It has been shown that Maculinea cuckoo larvae are able to reach a higher social status within the colony''s hierarchy by mimicking the acoustic signals of their host queen ants. In this research we tested if, when and how myrmecophilous butterflies may change sound emissions depending on their integration level and on stages of their life cycle. We studied how a Maculinea predatory species (M. teleius) can acoustically interact with their host ants and highlighted differences with respect to a cuckoo species (M. alcon). We recorded sounds emitted by Maculinea larvae as well as by their Myrmica hosts, and performed playback experiments to assess the parasites'' capacity to interfere with the host acoustic communication system. We found that, although varying between and within butterfly species, the larval acoustic emissions are more similar to queens'' than to workers'' stridulations. Nevertheless playback experiments showed that ant workers responded most strongly to the sounds emitted by the integrated (i.e. post-adoption) larvae of the cuckoo species, as well as by those of predatory species recorded before any contact with the host ants (i.e. in pre-adoption), thereby revealing the role of acoustic signals both in parasite integration and in adoption rituals. We discuss our findings in the broader context of parasite adaptations, comparing effects of acoustical and chemical mimicry.