43 research outputs found
A first broad-scale molecular phylogeny of Prionoceridae (Coleoptera: Cleroidea) provides insight into taxonomy, biogeography and life history evolution
© Senckenberg Gesellschaft fur Naturforschung, 2016. This is an open access article. Authors are permitted to post a PDF of their own articles, as provided by the publisher, on their personal web pages or the web page of their institution. Any commercial use is excluded. The attached file is the published version of the article
Species-specific or assemblage-wide decline? The case of Arthroleptides dutoiti Loveridge, 1935 and the amphibian assemblage of Mount Elgon, Kenya
The frog Arthroleptides dutoiti Loveridge, 1935, endemic to Mount Elgon, East Africa was last collected in 1962 and has not been observed since. The species is regarded as Critically Endangered by the IUCN Red List and is a priority species on the Zoological Society of London’s EDGE (Evolutionarily Distinct, Globally Endangered) project, given its Red List status and phylogenetic distinctiveness. We analyse temporal patterns of abundance (1934–2014) of A. dutoiti and the remainder of the Mount Elgon amphibian assemblage to infer the probability of re-encountering A. dutoiti and assess whether declines are species specific to A. dutoiti, or whether they are assemblage-wide phenomena. Our results show that for localities where surveys have been repeatedly conducted, A. dutoiti is likely to be locally extinct. Declines are observed in other Mount Elgon amphibians, encompassing both specialists and generalists. Causal factors for declines are unknown, but habitat change might be important, given the high degree of forest loss in the area, especially since the turn of the 20th century. Urgent sampling of preferred microhabitats of A. dutoiti at the type locality and surrounding areas beyond those included in our study are required to determine whether or not the species is extinct. Impacts on other taxonomic groups would also be useful to understand so that it can be determined how broad the changes are for the Mount Elgon biota
Parental investment by skin feeding in a caecilian amphibian
Although the initial growth and development of most multicellular animals depends on the provision of yolk, there are many varied contrivances by which animals provide additional or alternative investment in their offspring(1). Providing offspring with additional nutrition should be favoured by natural selection when the consequent increased fitness of the young offsets any corresponding reduction in fecundity(2). Alternative forms of nutrition may allow parents to delay and potentially redirect their investment. Here we report a remarkable form of parental care and mechanism of parent-offspring nutrient transfer in a caecilian amphibian. Boulengerula taitanus is a direct-developing, oviparous caecilian(3), the skin of which is transformed in brooding females to provide a rich supply of nutrients for the developing offspring. Young animals are equipped with a specialized dentition, which they use to peel and eat the outer layer of their mother's modified skin. This new form of parental care provides a plausible intermediate stage in the evolution of viviparity in caecilians. At independence, offspring of viviparous and of oviparous dermatotrophic caecilians are relatively large despite being provided with relatively little yolk. The specialized dentition of skin-feeding (dermatophagous) caecilians may constitute a pre-adaptation to the fetal feeding on the oviduct lining of viviparous caecilians.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62957/1/nature04403.pd
Terrestrialization, Miniaturization and Rates of Diversification in African Puddle Frogs (Anura: Phrynobatrachidae)
Terrestrialization, the evolution of non-aquatic oviposition, and miniaturization, the evolution of tiny adult body size, are recurring trends in amphibian evolution, but the relationships among the traits that characterize these phenomena are not well understood. Furthermore, these traits have been identified as possible “key innovations” that are predicted to increase rates of speciation in those lineages in which they evolve. We examine terrestrialization and miniaturization in sub-Saharan puddle frogs (Phrynobatrachidae) in a phylogenetic context to investigate the relationship between adaptation and diversification through time. We use relative dating techniques to ascertain if character trait shifts are associated with increased diversification rates, and we evaluate the likelihood that a single temporal event can explain the evolution of those traits. Results indicate alternate reproductive modes evolved independently in Phrynobatrachus at least seven times, including terrestrial deposition of eggs and terrestrial, non-feeding larvae. These shifts towards alternate reproductive modes are not linked to a common temporal event. Contrary to the “key innovations” hypothesis, clades that exhibit alternate reproductive modes have lower diversification rates than those that deposit eggs aquatically. Adult habitat, pedal webbing and body size have no effect on diversification rates. Though these traits putatively identified as key innovations for Phrynobatrachus do not seem to be associated with increased speciation rates, they may still provide opportunities to extend into new niches, thus increasing overall diversity
Molecular phylogenetics reveal multiple tertiary vicariance origins of the African rain forest trees
Background - Tropical rain forests are the most diverse terrestrial ecosystems on the planet. How this diversity evolved remains largely unexplained. In Africa, rain forests are situated in two geographically isolated regions: the West-Central Guineo-Congolian region and the coastal and montane regions of East Africa. These regions have strong floristic affinities with each other, suggesting a former connection via an Eocene pan-African rain forest. High levels of endemism observed in both regions have been hypothesized to be the result of either 1) a single break-up followed by a long isolation or 2) multiple fragmentation and reconnection since the Oligocene. To test these hypotheses the evolutionary history of endemic taxa within a rain forest restricted African lineage of the plant family Annonaceae was studied. Molecular phylogenies and divergence dates were estimated using a Bayesian relaxed uncorrelated molecular clock assumption accounting for both calibration and phylogenetic uncertainties. Results - Our results provide strong evidence that East African endemic lineages of Annonaceae have multiple origins dated to significantly different times spanning the Oligocene and Miocene epochs. Moreover, these successive origins (c. 33, 16 and 8 million years ¿ Myr) coincide with known periods of aridification and geological activity in Africa that would have recurrently isolated the Guineo-Congolian rain forest from the East African one. All East African taxa were found to have diversified prior to Pleistocene times. Conclusion - Molecular phylogenetic dating analyses of this large pan-African clade of Annonaceae unravels an interesting pattern of diversification for rain forest restricted trees co-occurring in West/Central and East African rain forests. Our results suggest that repeated reconnections between the West/Central and East African rain forest blocks allowed for biotic exchange while the break-ups induced speciation via vicariance, enhancing the levels of endemicity. These results provide an explanation for present day distribution patterns and origins of endemicity for African rain forest trees. Moreover, given the pre-Pleistocene origins of all the studied endemic East African genera and species, these results also offer important insights for setting conservation priorities in these highly diversified but threatene
Next-generation mitogenomics: A comparison of approaches applied to caecilian amphibian phylogeny
Mitochondrial genome (mitogenome) sequences are being generated with increasing speed due to the advances of next-generation sequencing (NGS) technology and associated analytical tools. However, detailed comparisons to explore the utility of alternative NGS approaches applied to the same taxa have not been undertaken. We compared a 'traditional' Sanger sequencing method with two NGS approaches (shotgun sequencing and non-indexed, multiplex amplicon sequencing) on four different sequencing platforms (Illumina's HiSeq and MiSeq, Roche's 454 GS FLX, and Life Technologies' Ion Torrent) to produce seven (near-) complete mitogenomes from six species that form a small radiation of caecilian amphibians from the Seychelles. The fastest, most accurate method of obtaining mitogenome sequences that we tested was direct sequencing of genomic DNA (shotgun sequencing) using the MiSeq platform. Bayesian inference and maximum likelihood analyses using seven different partitioning strategies were unable to resolve compellingly all phylogenetic relationships among the Seychelles caecilian species, indicating the need for additional data in this case
Leaf colour as a signal of chemical defence to insect herbivores in wild cabbage (Brassica Oleracea)
Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour
A new species of Boulengerula Tornier, 1896 (Amphibia: Gymnophiona: Herpelidae) from Kenya and the “rediscovery” of Boulengerula denhardti
A new species of herpelid caecilian, Boulengerula spawlsi sp. nov., is described based on nine specimens from Ngaia (= Ngaya or Ngaja) Forest Reserve, Nyambene Hills, Meru County, Kenya collected between 2007 and 2013. The new species differs from all other Boulengerula in having more anteriorly positioned tentacular apertures and tentacular grooves that are partly or completely covered by the maxillopalatines. Specimens of the new species were previously erroneously reported as a rediscovery of the poorly known congener Boulengerula denhardti Neiden, 1912 together with a biogeographic scenario to explain their disjunct distribution that is not required.Copyright © 2017 Magnolia Press. Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0. The attached file is the published version of the article.NHM Repositor