A new vertebrate species native to the British isles: Bufo spinosus Daudin, 1803 in Jersey

Recent molecular and morphological studies have shown that Bufo bufo and B. spinosus are genetically distinct and morphologically diagnosable across a relatively narrow contact zone in northern France and should be regarded as different species. However, the species identity of the neighbouring populations of Bufo on the British Channel Island of Jersey has not been investigated. We here present new molecular (a mtDNA RFLP assay plus sequences of the nuclear RAG1 gene) and morphological evidence that these populations are to be assigned to B. spinosus, and can thus be considered an addition to the native British herpetofauna. Jersey toad populations are declining and have a distinct breeding ecology compared to other populations in mainland Britain. We discuss the results in the light of amphibian conservation efforts in Jersey.Fieldwork and sampling in Jersey was conducted under licence from the States of Jersey Environment Department and with support from Amphibian and Reptile Conservation. Other funds were provided by grants CGL2008-04271-C02-01/BOS and CGL2011-28300 (Ministerio de Ciencia e Innovación, Ministerio de Economía y Competitividad, Spain, and FEDER) and PPII10-0097- 4200 (Junta de Comunidades de Castilla la Mancha and FEDER) to IMS, who is currently funded by Project “Biodiversity, Ecology and Global Change”, co-financed by North Portugal Regional Operational Programme 2007/2013 (ON.2–O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).Peer Reviewe

How complex is the Bufo bufo species group?

Species delineation remains one of the most challenging tasks in the study of biodiversity, mostly owing to the application of different species concepts, which results in contrasting taxonomic arrangements. This has important practical consequences, since species are basic units in fields like ecology and conservation biology. We here review molecular genetic evidence relevant to the systematics of toads in the Bufo bufo species group (Anura, Bufonidae). Two studies recently published in this journal (Recuero et al., MPE 62: 71-86 and García-Porta et al., MPE 63: 113-130) addressed this issue but reached opposing conclusions on the taxonomy of the group (four versus two species). In particular, allozyme data in the latter paper were interpreted as evidence for hybridization across species (between B. bufo-B. spinosus and B. bufo-B. verrucosissimus). We tested claims for hybridization through re-analysis of allozyme data for individuals instead of populations, to be able to distinguish between sympatry with and without admixture, and found no evidence of hybridization across taxa. We propose alternative explanations for the observed patterns that García-Porta et al. (2012) failed to consider. In the absence of unequivocal evidence for hybridization and introgression, we reject the proposal to downgrade Bufo spinosus and Bufo verrucosissimus to the subspecies level.IMS is a "Ramón y Cajal" postdoctoral fellow supported by the Spanish Ministerio de Ciencia e Innovación and the Universidad de Castilla la Mancha. Partial funds for this work were provided by grants CGL2008-04271-C02-01/BOS and CGL2011-28300 (Ministerio de Ciencia e Innovación, Ministerio de Economía y Competitividad, FEDER) and PPII10-0097-4200 (Junta de Comunidades de Castilla la Mancha) to IMS.Peer Reviewe

Multilocus species tree analyses resolve the radiation of the widespread Bufo bufo species group (Anura, Bufonidae)

et al.New analytical methods are improving our ability to reconstruct robust species trees from multilocus datasets, despite difficulties in phylogenetic reconstruction associated with recent, rapid divergence, incomplete lineage sorting and/or introgression. In this study, we applied these methods to resolve the radiation of toads in the Bufo bufo (Anura, Bufonidae) species group, ranging from the Iberian Peninsula and North Africa to Siberia, based on sequences from two mitochondrial and four nuclear DNA regions (3490. base. pairs). We obtained a fully-resolved topology, with the recently described Bufo eichwaldi from the Talysh Mountains in south Azerbaijan and Iran as the sister taxon to a clade including: (1) north African, Iberian, and most French populations, referred herein to Bufo spinosus based on the implied inclusion of populations from its type locality and (2) a second clade, sister to B. spinosus, including two sister subclades: one with all samples of Bufo verrucosissimus from the Caucasus and another one with samples of B. bufo from northern France to Russia, including the Apennine and Balkan peninsulas and most of Anatolia. Coalescent-based estimations of time to most recent common ancestors for each species and selected subclades allowed historical reconstruction of the diversification of the species group in the context of Mediterranean paleogeography and indicated a long evolutionary history in this region. Finally, we used our data to delimit the ranges of the four species, particularly the more widespread and historically confused B. spinosus and B. bufo, and identify potential contact zones, some of which show striking parallels with other co-distributed species.IMS is a “Ramón y Cajal” postdoctoral fellow supported by the Spanish Ministerio de Ciencia e Innovación and the Universidad de Castilla la Mancha. The Synthesis Project (http://www.synthesys.info/) of the European Union partially supported this study (Ref.: HU-TAF-181). Partial funds were also provided by the Spanish Ministerio de Ciencia e Innovación (Ref.: CGL2008-04271-C02-01/ BOS) and Junta de Comunidades de Castilla la Mancha (Ref.: PPII10-0097-4200) to IMS, Hungarian Scientific Research Fund (OTKA K77841) to JV and Ministry of Education and Science of Republic of Serbia (Grant No. 173025) to JCI.Peer Reviewe

Morphological and molecular data to describe a hybrid population of the Common toad (Bufo bufo) and the Spined toad (Bufo spinosus) in western France

The use of hyper-variable markers across species is often hindered by low cross-species amplification success, a reduced level of polymorphism or a high frequency of null alleles. However, optimizing sets of reliable and informative markers that can be consistently amplified and scored across taxa is key to address questions about patterns of genetic diversity and structure, hybridization and speciation. Here we present 14 newly developed microsatellite markers in the Spined toad (Bufo spinosus), assess their polymorphism in two Iberian populations and test for cross-species amplification in the closely related Common toad (Bufo bufo). We then use the 12 loci co-amplifying in both species to the study of a morphologically intermediate population (Moyaux) from the contact zone in northwest France as well as reference populations of the two species from both sides of the contact zone. Individuals from Moyaux had mtDNA haplotypes of the two species and were identified as hybrids in analyses with software NewHybrids. These results provide solid evidence for ongoing hybridization between B. bufo and B. spinosus, with no apparent restrictions to gene flow.This research was funded by grants CGL2008-04271-C02-01/BOS and CGL2011-28300 (Ministerio de Ciencia e Innovación), Ministerio de Economía y Competitividad and FEDER) and PPII10-0097-4200 (Junta de Comunidades de Castilla la Mancha) to IMS. J. Gutiérrez-Rodríguez was supported by the Consejo Superior de Investigaciones Científicas of Spain (CSIC) and the European Social Fund (ESF) with a JAE-pre PhD fellowship. IMS was funded by the project ‘Biodiversity, Ecology and Global Change’, co-financed by North Portugal Regional Operational Programme 2007/2013 (ON.2–O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF) and by funding from the Spanish Severo Ochoa Program (SEV-2012-0262). IMS’s stay in Leiden was supported by a Naturalis Temminck fellowship.Peer reviewe

Data concatenation, Bayesian concordance and coalescent-based analyses of the species tree for the rapid radiation of Triturus newts

The phylogenetic relationships for rapid species radiations are difficult to disentangle. Here we study one such case, namely the genus Triturus, which is composed of the marbled and crested newts. We analyze data for 38 genetic markers, positioned in 3-prime untranslated regions of protein-coding genes, obtained with 454 sequencing. Our dataset includes twenty Triturus newts and represents all nine species. Bayesian analysis of population structure allocates all individuals to their respective species. The branching patterns obtained by data concatenation, Bayesian concordance analysis and coalescent-based estimations of the species tree differ from one another. The data concatenation based species tree shows high branch support but branching order is considerably affected by allele choice in the case of heterozygotes in the concatenation process. Bayesian concordance analysis expresses the conflict between individual gene trees for part of the Triturus species tree as low concordance factors. The coalescent-based species tree is relatively similar to a previously published species tree based upon morphology and full mtDNA and any conflicting internal branches are not highly supported. Our findings reflect high gene tree discordance due to incomplete lineage sorting (possibly aggravated by hybridization) in combination with low information content of the markers employed (as can be expected for relatively recent species radiations). This case study highlights the complexity of resolving rapid radiations and we acknowledge that to convincingly resolve the Triturus species tree even more genes will have to be consulted

Drivers of amphibian population dynamics and asynchrony at local and regional scales

Identifying the drivers of population fluctuations in spatially distinct populations remains a significant challenge for ecologists. Whereas regional climatic factors may generate population synchrony (i.e., the Moran effect), local factors including the level of density-dependence may reduce the level of synchrony. Although divergences in the scaling of population synchrony and spatial environmental variation have been observed, the regulatory factors that underlie such mismatches are poorly understood. Few previous studies have investigated how density-dependent processes and population-specific responses to weather variation influence spatial synchrony at both local and regional scales. We addressed this issue in a pond-breeding amphibian, the great crested newt (Triturus cristatus). We used capture-recapture data collected through long-term surveys in five T. cristatus populations in Western Europe. In all populations – and subpopulations within metapopulations – population size, annual survival and recruitment fluctuated over time. Likewise, there was considerable variation in these demographic rates between populations and within metapopulations. These fluctuations and variations appear to be context-dependent and more related to site-specific characteristics than local or regional climatic drivers. We found a low level of demographic synchrony at both local and regional levels. Weather has weak and spatially variable effects on survival, recruitment and population growth rate. In contrast, density-dependence was a common phenomenon (at least for population growth) in almost all populations and subpopulations. Our findings support the idea that the Moran effect is low in species where the population dynamics more closely depends on local factors (e.g. population density and habitat characteristics) than on large-scale environmental fluctuation (e.g. regional climatic variation). Such responses may have far-reaching consequences for the long-term viability of spatially structured populations and their ability to response to large-scale climatic anomalies

Sex-related differences in aging rate are associated with sex chromosome system in amphibians

Sex-related differences in mortality are widespread in the animal kingdom. Although studies have shown that sex determination systems might drive lifespan evolution, sex chromosome influence on aging rates have not been investigated so far, likely due to an apparent lack of demographic data from clades including both XY (with heterogametic males) and ZW (heterogametic females) systems. Taking advantage of a unique collection of capture-recapture datasets in amphibians, a vertebrate group where XY and ZW systems have repeatedly evolved over the past 200 million years, we examined whether sex heterogamy can predict sex differences in aging rates and lifespans. We showed that the strength and direction of sex differences in aging rates (and not lifespan) differ between XY and ZW systems. Sex-specific variation in aging rates was moderate within each system, but aging rates tended to be consistently higher in the heterogametic sex. This led to small but detectable effects of sex chromosome system on sex differences in aging rates in our models. Although preliminary, our results suggest that exposed recessive deleterious mutations on the X/Z chromosome (the "unguarded X/Z effect") or repeat-rich Y/W chromosome (the "toxic Y/W effect") could accelerate aging in the heterogametic sex in some vertebrate clades.Peer reviewe

FIGURE 1 in Coexistence of two newt species in a transition zone of range overlap

FIGURE 1 Land use map of the study area in the western part of the department Pas de Calais in the northwest of France (see insert), after Curado et al. (2011) and Arntzen et al. (2017). The small-bodied newt species Lissotriton helveticus and L. vulgaris are frequently syntopic (for data see table 1), but have different strongholds in and outside the 'Dunes de la Slack' and the bomb crater areas, respectively. The partial spatial separation is illustrated by dotted contour lines where L. vulgaris is at 60% (red dots), 50% (purple dots) or 40% (blue dots) of the Lissotriton total. Note the position of the study pond at the species transition.Published as part of Arntzen, Jan W., 2022, Coexistence of two newt species in a transition zone of range overlap, pp. 133-151 in Contributions to Zoology 91 (2) on page 140, DOI: 10.1163/18759866-BJA10028, http://zenodo.org/record/834335