Cladistic Approaches in the Study of Soil and Plant Parasitic Nematodes

Cladistic analysis of free-living soil nematodes of the Leptonchoidea(Nematoda: Dorylaimida) resulted in groupings different fromthose obtained by traditional methods. We can interpret distributionsof species groups obtained by phyletic analysis in relationto plate tectonic events. Similar techniques are applicableto plant parasitic nematodes. Grouping on the basis of synapomorphiesproduced a cladogram of genera of the family Heteroderidae (Nematoda:Tylenchida) in which Meloidodera and Cryphodera appear to bethe most ancestral genera and the cyst forming genera the mostderived. A cladogram of groups of species in Heterodera sensulato showed a major division, with the round cyst nematodesand the Cacli group in one grouping and the rest of the Heteroderaspecies in the second. I interpret present-day distributionsby a strict vicariance view and suggest potential falsifiers;and also discuss ancient dispersal routes as alternative waysof thinking about nematode distribution.     

Endocrine Disruptors of the Stress Axis in Natural Populations: How Can We Tell?

Often, as environmental endocrinologists, we observe animalsin nature with the goal of describing their normal endocrinology.However, the contamination of virtually all natural habitatsby chemicals of anthropogenic origins (e.g., PCBs, organochlorines,phytoestrogens, alkyphenols, heavy metals) that might alterendocrine conditions suggests we need to reevaluate many ofour field studies with respect to points of reference or controls.The impaired response of the stress axis of feral brown trout,Salmo trutta, correlated with chronic exposure to heavy metalsis examined as a case in point although the problems extendto other hypothalamic axes as well. Our studies emphasize thatmeasurement of one static endocrine parameter to assess thehealth of any hypothalamus-pituitary axis (e.g., plasma cortisollevels to indicate stress) should not be used as a biomarkerfor field studies.     

Conservation and behavioral neuroendocrinology

The total number of threatened species of vertebrates is likely to be more than 10,000, with approximately one quarter of the world's mammal species, one eighth of the birds and one third of the amphibians threatened with extinction. The rate of loss of animal species and hence of biodiversity is increasing and may become even greater as ecosystems become affected by climate change due to global warming. Behavioral neuroendocrinology, which considers interactions between behavior and neuroendocrine function in animals from all vertebrate taxa, can contribute to animal conservation. Research with laboratory animals can address questions in basic biology relevant to conservation and develop methods for use with threatened animals. Field work with free-living animals considers the basic biology of new species and the use of endocrine tools to assess the susceptibility of species to threats. Non-invasive measurements of hormone concentrations, especially fecal steroids, are extensively used to assess reproductive function and the stress status of animals in captive breeding programs and in the wild. Biodiversity and natural selection both depend on individual variation, and conservation programs often work with animals on an individual basis. The consideration of data from individuals is essential in conservation endocrinology. Direct contributions to conservation programs are challenging as study situations are determined by practical conservation concerns. Indirect contributions such as the provision of scientific input to conservation plans and participation in public education programs offer significant benefits for conservation programs. Directly and indirectly, there are many opportunities for behavioral neuroendocrinologists to contribute to conservation.     

Disturbance-dependent Yellow-legged Gull (Larus michahellis) predation on Larid chicks decreases with chick age

Predation is one of the key factors shaping the dynamics of animal populations. In birds, nest loss due to predation can be a significant cause of low reproductive success. Ground-nesting birds are among the bird groups most susceptible to predation, mainly because their nests are easily accessible to a broad suite of potential predators. For these birds, anthropogenic disturbances can generate changes in nest predation risk by altering their antipredator behaviour and also by altering the behaviour of the predator species, i.e. the predator becoming much more aware of predation opportunities due to frequent disturbances and/or motivated to repeat predation attempts when some are successful. To date, most previous studies investigating this have focused on a single effect, either predation or disturbance, on chick survival. It remains unknown how the risk of predation with and without disturbance varies with chick age. In this study, we used behavioural observations to assess how the interaction between predators and disturbance affects predation risk in chicks and how this interacts with chick age. Specifically, we investigated the effect of disturbance caused by humans and stray dogs on the predation of Slender-billed Gull Chroicocephalus genei chicks by Yellow-legged Gulls Larus michahellis, and whether this depended on the age of the chicks. Our results revealed that disturbance had a significant positive effect on predation measures of Slender-billed Gull chicks by Yellow-legged Gulls, but that this effect was mediated both by disturbance type and the age of chicks. Stray dogs entering the colony had a stronger disturbance effect on chicks than passing humans, increasing predation risk by Yellow-legged Gulls. Our results also showed that chick age interacts with disturbance type to determine the predation risk. This is probably mediated by chicks' capacity to escape predation by gathering in a single large crèche that runs into the water when disturbed. To preserve Slender-billed Gull colonies in one of its few remaining breeding sites in Tunisia, and as gulls tend to react even when the disturbance occurs relatively far from the colonies, it is crucial to (1) restrict human access to dikes and islets where large colonies breed and (2) construct artificial islets attractive to gulls and inaccessible to stray dogs.     

A View of Comparative Endocrinology and Aubrey Gorbman

Analyses of papers published in General and Comparative Endocrinologyfrom 1961 to 1981 were made from several aspects. Number ofpapers published has increased year after year. Molluscan endocrinologypapers have increased and overtaken annelid publications. Duringthe past 20 yr studies using crustaceans and insects have comprised25–50% of all endocrine research on invertebrate groups.Papers on protochordates, elasmobranchs, and cyclostomes arefew but constant in number, indicating that these three groupsare important from phylogenic aspects. Studies on birds andteleosts have increased, while those on amphibians have decreased.Biochemical techniques were employed in 50% of all publicationsin this journal. Radioimmunoassay has replaced autoradiography.Immunohistochemistry increased in popularity. Studies on thepars distalis and gonads are predominant among all endocrineorgans. Research at the molecular level is decreasing, but isincreasing at the organismal level. Research at the organismallevel may be characteristic of comparative endocrinology. Largelythrough the initiative of Aubrey Gorbman, General and ComparativeEndocrinology was first published in 1961, and the InternationalCommittee of the Symposium on Comparative Endocrinology wasformed in 1957. Gorbman has produced many students. His originaland important contributions are in diversified areas: thyroidphysiology and its evolution, hormones and the brain and behavior,cyclostome endocrinology and neurosecretory systems in lowervertebrates. In addition, he has influenced investigators throughhis ideas of evolution. He has had particular impact on thedevelopment of comparative endocrinology in Japan.     

Avian defensive behavior and blood-feeding success of the West Nile vector mosquito, Culex pipiens

Avian defensive behavior against host-seeking arthropods influencestransmission of vector-borne pathogens by affecting mosquitobiting rate, either by preventing vector–host contactor by increasing the rate of multiple host feeding. We exposedhouse sparrows (Passer domesticus L.) and chickens (Gallus gallusdomesticus L.) to Culex pipiens pipiens L. overnight in a largeobservation cage and measured avian defensive behavior ratesand mosquito blood-feeding success. Both bird species exhibiteda range of defensive behaviors, 90% of which were foot stomps,head movements, and wing shakes. Total behavior rates increasedproportionately with mosquito density in both species, increasedafter the first hour of mosquito exposure, and decreased asindividual birds were exposed to mosquitoes multiple times.Mosquito blood-feeding success on house sparrows was high overall(82 ± 5%) and independent of behavior rates. Blood-feedingsuccess on chicks was lower (58 ± 5%) and negativelycorrelated with defensive behavior rate after the first hourof mosquito exposure. Results revealed a higher percentage ofpartial blood meals on chicks (18 ± 3% of all blood mealson chicks) than on house sparrows (4.9 ± 3%). Birds ofboth species ate an average of 9.4 ± 1.2% of mosquitoes,and this percentage was positively correlated with defensivebehavior. High mosquito feeding success on house sparrows supportsits role as a potential amplifying host of West Nile virus.     

Alligators and Endocrine Disrupting Contaminants: A Current Perspective

Many xenobiotic compounds introduced into the environment byhuman activity have been shown to adversely affect wildlife.Reproductive disorders in wildlife include altered fertility,reduced viability of offspring, impaired hormone secretion oractivity and modified reproductive anatomy. It has been hypothesizedthat many of these alterations in reproductive function aredue to the endocrine disruptive effects of various environmentalcontaminants. The endocrine system exhibits an organizationaleffect on the developing embryo. Thus, a disruption of the normalhormonal signals can permanently modify the organization andfuture function of the reproductive system. We have examinedthe reproductive and developmental endocrinology of severalpopulations of American alligator (Alligator mississippiensis)living in contaminated and reference lakes and used this speciesas a sentinel species in field studies. We have observed thatneonatal and juvenile alligators living in pesticide-contaminatedlakes have altered plasma hormone concentrations, reproductivetract anatomy and hepatic functioning. Experimental studiesexposing developing embryos to various persistent and nonpersistentpesticides, have produced alterations in gonadal steroidogenesis,secondary sex characteristics and gonadal anatomy. These experimentalstudies have begun to provide the causal relationships betweenembryonic pesticide exposure and reproductive abnormalitiesthat have been lacking in pure field studies of wild populations.An understanding of the developmental consequences of endocrinedisruption in wildlife can lead to new indicators of exposureand a better understanding of the most sensitive life stagesand the consequences of exposure during these periods.     

Aging and Reproduction: Comparative Endocrinology of the Common Tern and Japanese Quail

SYNOPSIS. The endocrinology of reproductive aging in avian specieshas been described primarily in captive domestic birds, suchas the Japanese quail (Coturnix japonica), which show majorchanges in hormones and reproductive performance. To explorereproductive aging in longer-lived avian species, longitudinalstudies are being conducted on the Common Tern (Sterna hirundo)in which age-related changes in nesting patterns and clutchsize have been monitored. However, little information is availablerelevant to endocrine status of breeding pairs of Common Terns.This review summarizes information pertinent to the breedingbiology and endocrine status of the Common Tern during reproductiveaging and compares these findings to data available from theJapanese quail. Fundamental mechanisms in the process of agingin avian species may become apparent in the comparison of thesedata and data from field species.     

Effects of social environment on baseline glucocorticoid levels in a communally breeding rodent,the colonial tuco-tuco (Ctenomys sociabilis)

The social environment in which an animal lives can profoundly impact its physiology, including glucocorticoid (GC) responses to external stressors. In social, group-living species, individuals may face stressors arising from regular interactions with conspecifics as well as those associated with basic life history needs such as acquiring food or shelter. To explore the relative contributions of these two types of stressors on glucocorticoid physiology in a communally breeding mammal, we characterized baseline GC levels in female colonial tuco-tucos (Ctenomys sociabilis), which are subterranean rodents endemic to southwestern Argentina. Long-term field studies have revealed that while about half of all yearling female C. sociabilis live and breed alone, the remainder live and breed within their natal group. We assessed the effects of this intraspecific variation in social environment on GC physiology by comparing concentrations of baseline fecal corticosterone metabolite (fCM) for (1) lone and group-living yearling females in a free-living population of C. sociabilis and (2) captive yearling female C. sociabilis that had been experimentally assigned to live alone or with conspecifics. In both cases, lone females displayed significantly higher mean baseline fCM concentrations. Data from free-living animals indicated that this outcome arose from differences in circadian patterns of GC production. fCM concentrations for group-living animals declined in the afternoon while fCM in lone individuals did not. These findings suggest that for C. sociabilis, stressors associated with basic life history functions present greater challenges than those arising from interactions with conspecifics. Our study is one of the first to examine GC levels in a plural-breeding mammal in which the effects of group-living are not confounded by differences in reproductive or dominance status, thereby generating important insights into the endocrine consequences of group-living.     

Ecological and evolutionary significance of cyclopoid predation on fish larvae

Of 412 cyclopoids found preying on fish larvae in Lake Michigan,411 were adult females. It is suggested that adult, female cyclopoidpredation on fish larvae may represent an important mechanismboth to reduce intraspecific competition for food (i.e. betweensexes) and maximize net energy intake for reproduction. Ourobservations of cyclopoid predation on fish larvae in naturemay also provide complementary evidence on how freshwater parasiticcyclopoids evolved from free-living ancestors. Freshwater, parasiticcyclopoids may have evolved from an ancestral free-living cyclopoidwhich was predaceous on small organisms, to a free-living cyclopoid(e.g. Acanthocyclops vernalis and Diacyclops thomasi) whichwas predaceous on larger prey such as fish larvae. Evolutionthen could have proceeded to a free-living cyclopoid with intermediatemorphological modification of its second antennae (e.g. Ergasiluschautauquaensis), and finally to a parasitic cyclopoid whichmorphologically exhibits a high degree of modification in itssecond antennae (e.g. many species of Ergasilus).     

Determination of non-market values to inform conservation strategies for the threatened Alistana–Sanabresa cattle breed

Livestock breed-related public good functions are often used to justify support for endangered breed conservation despite the fact that little is known about such non-market values. We show how stated preference techniques can be used to assess the non-market values that people place on livestock breeds. Through the application of a case study choice experiment survey in Zamora province, Spain, the total economic value (TEV) of the threatened Alistana–Sanabresa (AS) cattle breed was investigated. An analysis of the relative importance of the non-market components of its TEV and an assessment of the socio-economic variables that influence people’s valuation of such components is used to inform conservation strategy design. Overall, the findings reveal that the AS breed had significant non-market values associated with it and that the value that respondents placed on each specific public good function also varied significantly. Functions related with indirect use cultural and existence values were much more highly valued than landscape maintenance values. These high cultural and existence values (totalling over 80% of TEV) suggest that an AS in situ conservation strategy will be required to secure such values. As part of such a strategy, incentive mechanisms will be needed to permit farmers to capture some of these public good values and thus be able to afford to maintain breed population numbers at socially desirable levels. One such mechanism could be related to the development of breed-related agritourism initiatives, with a view to enhancing private good values and providing an important addition to continued direct support. Where linked with cultural dimensions, niche product market development, including through improving AS breed-related product quality and brand recognition may also have a role to play as part of such an overall conservation and use strategy. We conclude that livestock breed conservation strategies with the highest potential to maximise societal welfare would be those that secure the breed-related functions that people value most, with appropriate in situ conservation interventions and strategies being identified accordingly.     

The study of endocrine-disrupting compounds: past approaches and new directions

Over the last decade, evidence has mounted demonstrating thathuman-made compounds released into the environment are disruptingendocrine systems of animals. Research has centered largelyon direct steroidogenic or antisteroidogenic effects of thesecompounds with a recent focus on development of rapid in vitroassays employing estrogen receptors. A literature search andanalysis confirms attention placed on estrogen and anti-estrogen-likeaspects of endocrine disruption at the receptor level. Non-steroidalcomponents of the hypothalamic-pituitary-end gland axes havereceived much less attention in the published endocrine disruptionliterature. Furthermore, aspects of endocrine physiology, suchas the ability of animals to cope with stress or communicatechemically, have also received relatively less literature attentionwhen compared to disruption of development and reproduction.As researchers continue to investigate complex mixes of human-synthesizedcompounds in the environment, it is critical to broaden thespectrum of hormonal disruption investigated beyond estrogenicand androgenic actions and to determine how exposure to mixesaffects physiological function beyond reproduction. Last, inthe field of endocrine disruption, it also important to beginto use data on individuals for development of hypotheses regardingfitness risks, changes in population dynamics, and the potentialfor ecosystem level disruption.     

ECG Response of Koalas to Tourists Proximity: A Preliminary Study

Koalas operate on a tight energy budget and, thus, may not always display behavioral avoidance reaction when placed in a stressful condition. We investigated the physiological response of captive koalas Phascolarctos cinereus in a conservation centre to the presence of tourists walking through their habitat. We compared, using animal-attached data-recorders, the electrocardiogram activity of female koalas in contact with tourists and in a human-free area. One of the koalas in the tourist zone presented elevated heart rate values and variability throughout the recording period. The remaining female in the exhibit area showed a higher field resting heart rates during the daytime than that in the isolated area. In the evening, heart rate profiles changed drastically and both the koalas in the exhibit and in the tourist-free zones displayed similar field resting heart rates, which were lower than those during the day. In parallel, the autonomic nervous systems of these two individuals evolved from sympathetic-dominant during the day to parasympathetic-dominant in the evening. Our results report ECG of free-living koalas for the first time. Although they are preliminary due to the difficulty of having sufficient samples of animals of the same sex and age, our results stress out the importance of studies investigating the physiological reaction of animals to tourists.     

Colored plastic and metal leg bands do not affect survival of Piping Plover chicks

ABSTRACT Leg bands are commonly used to mark shorebird chicks as young as 1‐d old, but little is known about the possible impacts of bands on survival of prefledging shorebirds. We used a mark‐recapture framework to assess the impact of bands and banding‐related disturbance on prefledging survival in a federally endangered population of Piping Plovers (Charadrius melodus) breeding in the Great Lakes region from 2000 to 2008. We banded approximately 96% of all surviving chicks hatched prior to fledging, typically between 5 and 15 d of age. We used a multistate approach in program MARK whereby individuals contributed data as unbanded chicks before capture (N= 1073) and as banded chicks afterward (N= 780). The cumulative probability of surviving through 24 d of age was 0.63 and did not differ between banded and unbanded chicks. In addition, we found a positive effect of banding‐related disturbance on survival up to 3 d following banding (β= 0.60 CI: 0.17–1.02), possibly due to increased postbanding vigilance on the part of chicks and adults. Our results indicate that banding has no detrimental effect on survival of Piping Plover chicks prior to fledging and that current capture and banding methods are appropriate for this endangered species.     

Costly reproductive competition between females in a monogamous cooperatively breeding bird

In many cooperatively breeding societies, only a few socially dominant individuals in a group breed, reproductive skew is high, and reproductive conflict is common. Surprisingly, the effects of this conflict on dominant reproductive success in vertebrate societies have rarely been investigated, especially in high-skew societies. We examine how subordinate female competition for breeding opportunities affects the reproductive success of dominant females in a monogamous cooperatively breeding bird, the Southern pied babbler (Turdoides bicolor). In this species, successful subordinate reproduction is very rare, despite the fact that groups commonly contain sexually mature female subordinates that could mate with unrelated group males. However, we show that subordinate females compete with dominant females to breed, and do so far more often than expected, based on the infrequency of their success. Attempts by subordinates to obtain a share of breeding impose significant costs on dominant females: chicks fledge from fewer nests, more nests are abandoned before incubation begins, and more eggs are lost. Dominant females appear to attempt to reduce these costs by aggressively suppressing potentially competitive subordinate females. This empirical evidence provides rare insight into the nature of the conflicts between females and the resultant costs to reproductive success in cooperatively breeding societies.     

Territory and male quality do not influence settlement of yearling female willow ptarmigan

A common assumption in territory and mate selection models isthat individuals evaluate the qualities of territories and/orpartners and then choose the best ones. We determined whetherthis assumption was correct for yearling female willow ptarmigan(Lagopus lagopus). Yearling females did not choose partnersbased on the characteristics of the territories or of the malesthat we measured. In addition, the first females to settle didnot appear to obtain better territories or better partners thanthose settling later; date of settling was not related to subsequentsurvival, reproductive success, or quality of chicks produced.To evaluate whether choices of territories and partners wereconsistent among females, we manipulated settlement such thattwo sets of yearling females had the same suite of territoriesand males available. We found no consistent patterns of territoryand mate choice. We concluded that, in this population, yearlingfemales did not choose where to settle based on the relativequalities of territories or partners. Females may have beenunable to assess differences among territories when settlingbecause all territories were covered with snow.     

The Effect of Social Parasitism by Polyergus breviceps on the Nestmate Recognition System of Its Host,Formica altipetens

Highly social ants, bees and wasps employ sophisticated recognition systems to identify colony members and deny foreign individuals access to their nest. For ants, cuticular hydrocarbons serve as the labels used to ascertain nest membership. Social parasites, however, are capable of breaking the recognition code so that they can thrive unopposed within the colonies of their hosts. Here we examine the influence of the socially parasitic slave-making ant, Polyergus breviceps on the nestmate recognition system of its slaves, Formica altipetens. We compared the chemical, genetic, and behavioral characteristics of colonies of enslaved and free-living F. altipetens. We found that enslaved Formica colonies were more genetically and chemically diverse than their free-living counterparts. These differences are likely caused by the hallmark of slave-making ant ecology: seasonal raids in which pupa are stolen from several adjacent host colonies. The different social environments of enslaved and free-living Formica appear to affect their recognition behaviors: enslaved Formica workers were less aggressive towards non-nestmates than were free-living Formica. Our findings indicate that parasitism by P. breviceps dramatically alters both the chemical and genetic context in which their kidnapped hosts develop, leading to changes in how they recognize nestmates.     

Transitions in symbiosis: evidence for environmental acquisition and social transmission within a clade of heritable symbionts

A dynamic continuum exists from free-living environmental microbes to strict host-associated symbionts that are vertically inherited. However, knowledge of the forces that drive transitions in symbiotic lifestyle and transmission mode is lacking. Arsenophonus is a diverse clade of bacterial symbionts, comprising reproductive parasites to coevolving obligate mutualists, in which the predominant mode of transmission is vertical. We describe a symbiosis between a member of the genus Arsenophonus and the Western honey bee. The symbiont shares common genomic and predicted metabolic properties with the male-killing symbiont Arsenophonus nasoniae, however we present multiple lines of evidence that the bee Arsenophonus deviates from a heritable model of transmission. Field sampling uncovered spatial and seasonal dynamics in symbiont prevalence, and rapid infection loss events were observed in field colonies and laboratory individuals. Fluorescent in situ hybridisation showed Arsenophonus localised in the gut, and detection was rare in screens of early honey bee life stages. We directly show horizontal transmission of Arsenophonus between bees under varying social conditions. We conclude that honey bees acquire Arsenophonus through a combination of environmental exposure and social contacts. These findings uncover a key link in the Arsenophonus clades trajectory from free-living ancestral life to obligate mutualism, and provide a foundation for studying transitions in symbiotic lifestyle.Subject terms: Microbial ecology, Molecular evolution, Bacterial evolution, Bacterial genetics, Phylogenetics     

Physiological and analytical validations of fecal steroid hormone measures in black howler monkeys

The measurement of hormones in fecal samples allows for the noninvasive assessment of the endocrine status of free-ranging primates. However, procedures and techniques for hormone analysis in feces must be validated, both analytically and physiologically. Few studies have addressed the endocrinology of black howler monkeys (Alouatta pigra). Due to its conservation status, direct handling of individuals from this species and invasive sample collection are highly regulated, and therefore traditional methods for the validation of hormone assays, such as pharmacological challenges, are not allowed. As a consequence, sometimes studies of the fecal hormones of free-ranging black howler monkeys do not report physiological validations and therefore the biological reliability of such measurements cannot be assessed. In order to stimulate future research with this species, the present study aimed at providing methodological bases for fecal endocrine monitoring. Specifically, we compared the validity of two immunoassays (radioimmunoassays, RIA; solid-phase chemiluminescent enzyme immunoassay, SPCEI) performed with commercial kits to measure cortisol, testosterone, estradiol, and progesterone; and demonstrate how the physiological functions of these steroid hormones can be determined through non-pharmacological validations. We found no differences between the analytical validity of RIA and SPCEI assays to measure cortisol and testosterone, whereas for estradiol and progesterone RIA showed better results. Concerning the physiological validation of our assays, we demonstrated that: (1) comparisons between pre- and post-stress situations may be used to assess cortisol response, (2) comparisons between females and males may be used to assess variation in testosterone levels, and (3) comparisons between pregnant and non-pregnant females may be used to determine variation in estradiol and progesterone activity. The analytical and physiological validations that we performed demonstrate that there are currently commercial kits that allow for correct endocrine monitoring of this species, and that there are non-pharmacological alternatives to assess the biological validity of hormone measurements.