Ofer Mokady

A novel method using hair for determining hormonal levels in wildlife

ormones influence behaviour, and are also influ-enced by behaviour. Monitoring their levels cantherefore provide insights into the mechanistic aspects ofbehaviour. In male mammals for example, elevated levelsof testosterone are associated with increased aggressionand dominance (Creel et al. 1993, 1997; Mazur & Booth1998) and in social mammals, levels of stress hormones(e.g. corticosterone, glucocorticoid and cortisol) areassociated with rank (Sapolsky 1985; Creel et al. 1996,1997). Research has associated hormone levels with dif-ferent behaviours such as sexual, reproductive, courtship,parental, aggressive and feeding behaviours. Comparativetools for hormonal analysis provide insights into evolu-tionary theories based on behavioural aspects, such asreproductive suppression and the ‘challenge hypothesis’(e.g. Creel et al. 1993).In field studies, hormones are usually extracted fromblood samples, or noninvasively from saliva, urine andfaeces (Creel et al. 1992; Cavigelli 1999; Hirschenhauseret al. 1999; von Engelhardt et al. 2000). Samples derivedfrom trapped or handled animals are problematicalbecause stress may alter blood and urine hormonal levels(Creel et al. 1992). Additional problems with bloodsamples are that they are not always available, theamount that can be taken at a given time is limited, andvarious safety and ethical issues exist. Furthermore, bloodand saliva must be transported cold or frozen, conditionsthat are sometimes difficult to obtain in the field (Yang etal. 1998). Urine and faeces samples are sometimes diffi-cult to obtain from free-ranging animals that cannot becontinuously observed, or from species that deposit incommon latrines.An alternative source for hormones may be found inhair, which can be collected noninvasively, and is alreadyused to extract DNA (Woodruff 1993; Morin et al. 1994),trace metals, naturally occurring compounds and drugs(Wheeler et al. 1998). Hair is safe, readily available, andeasy to store and transport. Hair sampling does notinvolve pain or possible infection, and the analysis isunaffected by the momentary stress of capture (Yang et al.1998). Hair analysis may allow one to monitor hormonalchanges over weeks or months (between moults; Maurelet al. 1986) by shaving off a patch of hair and resamplingthe newly grown hair. Hormonal hair analysis offersonly a long-term profile, however, and is not suitable formonitoring hourly or daily (short-term) fluctuations inhormonal levels. It provides the resolution needed forstudies of main behavioural trends, especially in stablehierarchical social systems. Hair has already been used todiagnose early pregnancy in cows by detection of proges-terone (Liu et al. 1988), to detect oestradiol and testoster-one in cattle (Gleixner & Meyer 1997) and anabolicsteroid and corticosteroid abuse in athletes (Bowers S Hold et al. 1999; Kintz et al. 1999; Cirimeleet al. 2000). In humans, the levels of steroid hormones inhair do not vary significantly between different regions ofthe scalp (Wheeler et al. 1998). Oestradiol, progesteroneand testosterone levels measured in healthy humanadults’ hair correlate significantly with the levelsmeasured in their serum (Yang et al. 1998).As an example of the utility of this method, we usedata from our long-term study on rock hyrax,

Red to Mediterranean Sea bioinvasion: natural drift through the Suez Canal, or anthropogenic transport?

The biota of the eastern basin of the Mediterranean Sea has experienced dramatic changes in the last decades, in part as a result of the massive invasion of Red Sea species. The mechanism generally hypothesized for the ‘Red‐to‐Med’ invasion is that of natural dispersal through the Suez Canal. To date, however, this hypothesis has not been tested. This study examines the mode of invasion, using as a model the mussel Brachidontes pharaonis, an acclaimed ‘Lessepsian migrant’ that thrives along the eastern Mediterranean coast. Our findings reveal two distinct lineages of haplotypes, and five possible explanations are discussed for this observation. We show that the genetic exchange among the Mediterranean, Gulf of Suez and the northern Red Sea is sufficiently large to counteract the build up of sequential genetic structure. Nevertheless, these basins are rich in unique haplotypes of unknown origin. We propose that it is historic secondary contact, an ongoing anthropogenic transport or both processes, that participate in driving the population dynamics of B. pharaonis in the Mediterranean and northern Red Sea.

Echinoid Bioerosion as a Major Structuring Force of Red Sea Coral Reefs

Echinoid bioerosion is ecologically important as a limiting factor for reef growth. Diadema setosum and Echinometra mathaei are the most abundant sea urchins in the Gulf of Eilat, Red Sea. Bioerosion by these urchins was estimated from field experiments with urchins placed in underwater chambers. A novel methodology was developed for measuring the CaCO3 content of fecal pellets and total gut contents. This method is based on measurement of the amount of gas formed by total acidification of a mixed sample. The population density of the urchins was determined for the reef flat (depth 0.6-1 m) and the reef slope (depth 6-8 m). D. setosum, which erodes 310 mg individual-1 d-1, is much less abundant on the reef flat (0.1 individuals m-2) than on the reef slope (6.4 individuals m-2). In contrast, E. mathaei, which erodes 120 mg individual-1 d-1, is more dominant on the reef flat (10.5 individuals m-2) than on the reef slope (3.7 individuals m--2). We estimate that echinoid bioerosion converts to carbonate sediments 7%-11% of the total reef flat calcification and 13%-22% of the total reef slope calcification. These findings emphasize the importance of echinoid bioerosion as a structuring force in the coral reef, and its potential importance to the dynamics of reef development. However, they imply that some previous studies may have overestimated the role of echinoid bioerosion, thus possibly underestimating internal bioerosion.

Marine molluscs in environmental monitoring

Concentrations of trace elements and organic pollutants were determined in marine sediments and molluscs from the Mediterranean and Red Sea coasts of Israel. Two bivalve species (Donax trunculus, Pteria aegyptia), two gastropod species (Patella caerulea, Cellana rota) and sediments were sampled at polluted and relatively clean, reference, sites. Along the Mediterranean coast of Israel, sediments and molluscs from Haifa Bay stations were enriched with both organic and trace element contaminants. In the Red Sea, differences between the polluted and reference sites were less pronounced. Bio-concentration factors indicate a significant concentration of Zn, As, Cd, Sn and Pb in animal tissue relative to the concentrations of these elements in the sediments. In contrast, Ce, La and U were not concentrated in molluscs. The trace element results indicate a saturation of the detoxification mechanisms in molluscs from polluted sites. The concentrations of organic pollutants at the same sites are at the lower range of values recorded in other studies. However, synergistic effects between these compounds and between them and metals can lead to acute toxicity.

Song dialects do not restrict gene flow in an urban population of the orange-tufted sunbird, Nectarinia osea

Geographic variation in vocalizations is widespread in passerine birds, but its origins and maintenance remain unclear. In this study, we test the hypothesis that song dialect, a culturally transmitted trait, is related to the population genetic structure of the orange-tufted sunbird, Nectarinia osea. To address this, we compared mitochondrial DNA (mtDNA) sequence variation together with allele frequencies at five microsatellite loci from an urban population of sunbirds exhibiting two distinct song dialects on a microgeographic scale. Our findings reveal no association between dialect membership and genetic composition. All genetic measures, from both mitochondrial and nuclear DNA, indicate high levels of gene flow between both dialect populations. The low FST values obtained from mtDNA and microsatellite analysis imply that the variation among dialects does not account for more than 2%, at best, of the overall genetic variation found in the entire population. These measures fall well within the range of similar measures obtained in other studies of species exhibiting vocal dialects, most of which fail to detect any dialect-based genetic differentiation. The persistence of dialects in the orange-tufted sunbird may thus best be explained by dispersal of individuals across dialect boundaries and possibly from surrounding areas, followed by postdispersal vocal matching. Because genetic structuring appears weaker than cultural structure in this species, we discuss the behavioral mechanisms underlying dialect maintenance in the presence of apparent gene flow.

Phylogeny of the Baldratiina (Diptera : Cecidomyiidae) inferred from morphological, ecological and molecular data sources, and evolutionary patterns in plant-galler relationships

The phylogeny of the gall-midge subtribe Baldratiina (Diptera: Cecidomyiidae) was reconstructed from molecular (partial sequence of the mitochondrial 12S rDNA), morphological and ecological data sets, using 16 representative species of most of the genera. The morphological and ecological data were combined in a single character matrix and analyzed separately from the molecular data, resulting in an eco-morphological cladogram and a molecular cladogram. Attributes of galls and host associations were superimposed on the molecular cladogram in order to detect possible trends in the evolution of these traits. The cladograms resulting from the two independent analyses were statistically incongruent, although both provide evidence for the monophyly of the genera Baldratia and Careopalpis and the paraphyly of the genera Stefaniola and Izeniola. The results suggest a minor impact of the morphological characters traditionally used in the classification of the Baldratiina, whereas ecological data had a major impact on the phylogenetic inference. Mapping of gall and host attributes on the molecular cladogram suggests that multi-chambered stem galls constitute the ancestral state in the subtribe, with several subsequent shifts to leaf galls. It is concluded that in contrast to other studied groups of gall insects, related baldratiine species induce different types of galls, attesting to speciation driven by gall-type shifts at least as often as host shifts.

Coral host specificity in settlement and metamorphosis of the date mussel Lithophaga lessepsiana (Vaillant, 1865)

The boring bivalve Lithophaga lessepsiana is found only in the coral Stylophora pistillata Esper, 1797, in the Gulf of Eilat, Red Sea. In laboratory experiments, L. lessepsiana larvae were found to choose S. pistillata as a substratum for settlement significantly more than all other coral substrata offered (p < 0.001). Furthermore, larvae were induced to metamorphose by tissue extracts of their known host significantly more than by extracts of other corals (p < 0.001). Larvae maintained in laboratory cultures retained the ability to metamorphose for 4 mth, with only very low incidence of spontaneous metamorphosis Our experimental results suggest that larval choice of substratum, and specific triggering of metamorphosis by the coral host, act together to form the species specific association between L. lessepsiana and S. pistillata.

Speciation and the establishment of zonation in an intertidal barnacle: specific settlement vs. selection*

The tropical barnacle Tetraclita forms a belt on hard substrates in the intertidal zone of the Red Sea. Based on morphological data, three distinct species were suggested to exist, occupying different vertical levels — T. barnesorum, T. rufotincta and T. achituvi. In this study we used molecular (12S mitochondrial ribosomal DNA) and ecological data to examine whether this morphological variability reflects genetic differences, or is a result of environmental factors. Adults and spats, collected from settlement plates, were censused and screened genotypically using single strand conformation polymorphism (SSCP) analysis, and settlement dynamics was recorded. We provide evidence for the existence of only two distinct species, and point out both phenotypic plasticity and convergence within and between the proposed species. Cyprids of T. achituvi settle specifically at the lower part of the Tetraclita belt, and feature one phenotype. In contrast, T. rufotincta, occupying the upper and middle portions of the Tetraclita belt, settles throughout the range, shows phenotypic plasticity (three variants), and presumably undergoes selection at the lower part. Thus, the vertical zonation of Tetraclita is produced by the combination of pre‐settlement and post‐settlement factors, in T. achituvi and T. rufotincta, respectively. The examined system may offer a model in which to study the mechanisms underlying sympatric speciation.

Settlement and metamorphosis specificity of Lithophaga simplex Iredale (Bivalvia : Mytilidae) on Red Sea corals

Abstract Lithophaga simplex (Bivalvia:Mytilidae) inhabits only two species of live corals in the Red Sea: Astreopora myriophthalma (Lamarck) and Goniastrea pectinata (Ehrenberg). Larvae from mussels originating from both of these corals were offered a variety of coral substrata, either living corals or bleached skeletons, to assess the degree of specificity with regard to settlement substratum and metamorphosis. An index termed “combined chance of metamorphosis” (CCM) was used to compare the overall success of larval recruitment. Settlement was highest on A. myriophthalma for both populations of larvae, regardless of the coral from which they originated. Metamorphosis was induced only by living corals and was highest on the parent host coral. Overall recruitment success (indicated by the CCM value) was also highest on the parent host coral. It is hypothesized that L. simplex is undergoing speciation in a suggested direction.

The different morphs of Chthamalus anisopoma: a phenotypic response? Direct molecular evidence

Chthamalus anisopoma is a rock-inhabiting barnacle which appears in two radically different morphs: the shell may be either conical or bent at a right angle. Based on field experiments, it was previously concluded that the two morphs are phenotypic variants, with the bent morph being induced by the presence of a predator gastropod. In the present study we used molecular data in order to examine directly the degree of genetic similarity between the two morphs. We compared the sequences of two mitochondrial DNA segments previously shown to exhibit substantial inter- and intra-specific variability in barnacles: the 12S mt rDNA and the cytochrome C oxidase subunit 1 (CO1). The sequences obtained for the different C. anisopoma morphs showed complete identity (12S rDNA) or very high similarity (>99.5%, CO1). We thus provide direct genetic evidence indicating that barnacles of the different morphs originate from a common gene pool. This supports previous conclusions that predation in this case is an inductive factor rather than selective.