Organic Matter and Nitrogen Cycles in a Pine Afforested Catchment with a Shrub Layer of Adenocarpus decorticans and Cistus laurifolius in South-eastern Spain

Organic matter and nitrogen cycles in two mediterranean woodyshrubs (Adenocarpus decorticans Boiss. andCistus laurifoliusL.) and two pine species were investigated during 1987–1989in a small, recently pine-afforested catchment in Sierra delos Filabres (Almería Province, south-eastern Spain).Pine cover was sparse because canopy closure was not yet completed,allowing strong shrub colonization in the clearings. The aimof this study was to compare the contribution of different annualfluxes and the distribution of organic matter and nitrogen inboth shrub and pine components for the entire catchment. Specialemphasis was placed on the N use strategy shown by the two shrubspecies, a symbiotic N₂fixing species (A. decorticans) and anon-fixing species (C. laurifolius). Our results showed that the characteristics of C and N cyclingin the Nacimiento catchment are mainly determined by the earlystage of pine layer development and the significant contributionof the two shrub species differing with respect to C acquisitionand N use. The pine layer was characterized by a low standing biomass,substantial percentages of needle biomass and high (net production/biomass)and (needle production/total net production) ratios. N uptakewas mainly diverted to biomass increment, as shown by the substantialallocation found in this study. Overall, these results are consistentwith the patterns described for even-aged stands during theearly-growth phase. Retranslocation supplied 21% of the annualN requirements for pine above-ground biomass production. C. laurifolius showed low litter-fall return, strong retranslocation,efficient utilization of N in bulk deposition and slow decomposition,suggesting a closer, self-regulated organic matter and N-conservingbehaviour thanA. decorticans . On the contrary,A. decorticansshowed high leaf turnover, strong litter-fall return, low retranslocationand fast mineralization of organic matter and nitrogen, indicatingthat internal organic matter and N cycling is less efficient,and thus, that this species is more dependent on the soil tomeet its N requirements. Adenocarpus decorticans Boiss.; biogeochemical cycles,Cistus laurifolius L.; mediterranean shrubs; nitrogen fixation; nitrogen use; pine afforestation; south-eastern Spain; woody legumes     

Multiple barriers to gene exchange in a field cricket hybrid zone

Data on patterns of variation within hybrid zones, combined with studies of life history, mate choice, and hybrid performance, allow estimates of the contribution of different pre-zygotic and post-zygotic barriers to reproductive isolation. We examine the role of behavioural barriers to gene exchange in the maintenance of a hybrid zone between North American field crickets Gryllus firmus and Gryllus pennsylvanicus . We consider these barriers in the context of previous studies that documented temporal and ecological isolation and a one-way post-mating incompatibility (i.e. G. firmus females do not produce offspring when they mate only with heterospecific males). Based on no-choice mating experiments in the laboratory, we demonstrate strong behavioural pre-mating barriers between the two species, but no apparent fecundity or fertility costs for G. firmus females when they mate with both conspecific and heterospecific males. Furthermore, we show that G. firmus females do not discriminate between hybrids and conspecifics, whereas G. pennsylvanicus females do. This observation could explain the asymmetric allele introgression observed in the hybrid zone. We also document a failure of heterospecific males to induce normal oviposition in G. firmus females, which may be due to rapid evolution of accessory gland proteins and may serve as an additional barrier to gene exchange.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 390–402.     

Palynology of South Indian Zingiberaceae

MANGALY, J. K. & NAYAR, J. 1990. Palynology of South Indian Zingiberaceae. Light microscope studies on pollen morphology of 21 Old World, tropical taxa of Zingiberaceae reveal that an exine is absent only in Kaempferia . A discontinuous exine layer consisting of circular plates joined together at margins occurs in Alpinia galanga and Amomum hypoleucum while all other taxa possess an uninterrupted exine layer which is commonly 0.7 μm to less than 2.0 μrn thick (3.2 μm in Zingiber zerumbet , 2.5 μm in Amomum hypoleucum ). Exine is spinose in Alpinia (smooth in Alpinia sanderae ), Amomum and Boesenbergia , verrucose in Eleltaria , tuberculate to areolate or striate in Zingiber , papillose in Globba and smooth or nearly so in Curcuma, Costus and Hedychiurn . Pollen grains are spheroidal, 50–90 μm in size (35 μm in Globba ophioglossa ), and inaparturate (foraminate in Costus ), except in Curcuma and Zingiber where they are ovoid to ellipsoidal, 70–135 times 60–80 μm in size and sulcate. A lamellated intine, much thicker than the exine, occurs in all, and it is thinner at the apertural region in Curcuma, Costus and Zingiber; in Elettaria and Hedychiurn it is thinner in one or few large scattered circular areas, and in Boesenbergia and Alpinia zerumbet on one side of the grains. Palynologirally Alpinia, Amomum, Boesenbergia, Kaempferia and Zingiber constitute one group while Elettaria, Hedychiurn and Costus constitute another.     

Effects of habitat heterogeneity and local adaptation on the body condition of a forest passerine at the edge of its distributional range

We studied fluctuating asymmetry and feather growth rates as indicators of fitness of blackcaps ( Sylvia atricapilla ) breeding at the border of their distribution range in the Iberian Peninsula. Iberian blackcaps increase their abundance with increasing rainfall and ground cover of brambles. In border habitats, they are sedentary and morphologically different from migrants, suggesting that they could be adapted to peripheral conditions. We tested whether juvenile body condition depends on (1) distance from the centre of the range, (2) mean precipitation or (3) bramble cover. Controlling for environmental variation, we tested for differences between migratory and sedentary populations. Body condition varied across the Iberian gradient in parallel with changes in precipitation. Controlling for this effect, sedentary populations were in better body condition than migratory populations. Our results support the idea that environmental heterogeneity causes fitness to fluctuate across species' ranges, and also that local adaptation may mean that peripheral populations are more than a 'tail end' of the species.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 479–488.     

Do all Blackcaps Sylvia atricapilla show winter site fidelity?

Fidelity to previous wintering areas (i.e. site fidelity) has important ecological and evolutionary implications. However, since the percentage of recaptures of ringed birds at the same wintering area in subsequent years does not allow the estimation of the proportion of birds alive that exhibit site fidelity, previous studies on different passerine species have failed to show the true extent of this site fidelity. Here we use a recent approach, based on the comparison of survival rate estimates from capture-recapture data at single field stations with recovery data from a much larger area. The idea is to determine the proportion of birds still alive that return to the area. The study was carried out on the Blackcap Sylvia atricapilla , comparing the capture-recapture data of two field stations (Pilas [SW] and Tiana [NE]) situated 1000 km apart in Spain with the complete winter recovery data of the Spanish Ringing Office. Totals of 1936 and 3976 Blackcaps were ringed at Pilas (1981–1986) and Tiana (1975–1986), respectively, and the numbers of recaptures in subsequent winters were 94 and 34. The pooled annual survival rate estimation based on the two sites is 0.40 (s.e. = 0.05). The annual survival rate estimated from the Spanish ringing recovery data was 0.48 (s.e. = 0.08), which is not significantly different. We can conclude, therefore, that migrant Blackcaps in Spain, if alive, tend to return year after year to the previous wintering site.     

A NEW SPECIES OF BERTHELLA BLAINVILLE, 1824 (OPISTHOBRANCHIA: NOTASPIDEA) FROM THE CANARY ISLANDS (EASTERN ATLANTIC OCEAN), WITH A RE-EXAMINATION OF THE PHYLOGENETIC RELATIONSHIPS OF THE NOTASPIDEA

Berthella canariensis is described from Canary Islands. Themantle is smooth and its ground colour is grey, with black andopaque white spots scattered regularly all over the dorsal surface.White spots are less abundant than black ones. The posterior halfof the mantle has areas of with a paler ground colour that are variablein size. Berthella canariensis has several features that distinguishit from other described members of Berthella. It had a broadradula with numerous teeth per half-row. However, other aspectsof its anatomy, such as the absence of a medial buccal glandand the presence of a tuberculate gill, distinguish it fromother species with a broad radula. As the present species has two features found in some speciesof Pleurobranchus and several new higher taxa have been describedrecently, Willan's (1987) phylogenetic hypothesis was re-analysed.This analysis largely supports the hypothesis presented by Willan. The sister-group relationship of B. Canariensis with B. californiais supported by two synapomorphies. The relationship of thesetwo species to other species of Berthella is poorly resolvedin the present analysis and requires additional study of allmembers of the genus. Similarly, questions of the monophylyof Bathyberthella, Polictenidia, Parabathyberthella, Tomthompsoniaand Berthella require the consideration of additional speciesand comparison with other member of Berthella and Berthellina. Despite the need for further study, the mohophyly of the cladecontaining Bathyberthella, Polictenidia, Parabathyberthellais well supported. Similarly, numerous synapomorphic featuresconfirm the monophyly of the clade containing Bathyberthella,Polictenidia, Parabathyberthella, Tomthompsonia, Berthellinaand Berthella, and its sister-group relationship with the Pleurobranchus. The present study reveals that the Notaspidea have three distinctconfigurations of triaulic reproductive systems, not previouslydifferentiated. (Received 19 January 1998; accepted 15 November 1999)     

Blastocrithidia triatomae n. sp. Found in Triatoma infestans from Argentina

SYNOPSIS. Blastocrithidia triatomae n. sp. found in the digestive tract of T. infestans in Argentina is described. Cysts attached to the flagellum, a conspicuous characteristic of the new species, are described and shown in photomicrographs. Since T. infestans may harbor both T. cruzi and B. triatomae, or either one independently, it is essential that they be distinguished in xenodiagnosis.     

Can a sponge feeder be a herbivore? Tylodina perversa (Gastropoda) feeding on Aplysina aerophoba (Demospongiae)

Feeding biology in mollusks has important biological, ecological and evolutionary implications because many of the characteristics we observe in mollusks arise from their co-evolution with diet organisms. We investigated the relationship between the opisthobranch Tylodina perversa and the sponges Aplysina aerophoba and Aplysina cavernicola in order to ascertain the trophic interactions between them. The opisthobranch preferred specimens of Aplysina aerophoba inhabiting shallow overdeep waters, ectosome of Aplysina aerophoba over choanosome, and showed no preference for Aplysina cavernicola . The sponge Aplysina cavernicola lacks the cyanobacteria abundant in the ectosome of Aplysina aerophoba . Our study shows that the opisthobranch Tylodina perversa actively selects for sponges or sponge zones with high concentration of cyanobacteria, i.e. only a fraction of the ingested material is of animal origin. Addition of cyanobacteria to symbiont-free sponge material induced a shift in mollusk preference. Our results cast doubt over the widely recognized qualification of Tylodina perversa as a carnivorous sponge feeder and show evidence that cyanobacteria determine the opisthobranch food selection. Whether this is an isolated example of how symbionts may determine trophic interactions between hosts and predators or it is widespread in benthic organisms remains an open question that requires further investigation.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 429–438.