Alexander Kupfer

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. 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. 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, 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 mothers 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 preadaptation to the fetal feeding on the oviduct lining of viviparous caecilians.

One hundred million years of skin feeding? Extended parental care in a Neotropical caecilian (Amphibia: Gymnophiona)

Maternal dermatophagy, the eating of maternal skin by offspring, is an unusual form of parental investment involving co-evolved specializations of both maternal skin and offspring dentition, which has been recently discovered in an African caecilian amphibian. Here we report the discovery of this form of parental care in a second, distantly related Neotropical species Siphonops annulatus, where it is characterized by the same syndrome of maternal and offspring specializations. The detailed similarities of skin feeding in different caecilian species provide strong evidence of its homology, implying its presence in the last common ancestor of these species. Biogeographic considerations, the separation of Africa and South American land masses and inferred timescales of amphibian diversification all suggest that skin feeding is an ancient form of parental care in caecilians, which has probably persisted in multiple lineages for more than 100 Myr. These inferences support the hypotheses that (i) maternal dermatophagy is widespread in oviparous direct-developing caecilians, and (ii) that viviparous caecilians that feed on the hypertrophied maternal oviduct evolved from skin-feeding ancestors. In addition to skin-feeding, young S. annulatus were observed to congregate around, and imbibe liquid exuded from, the maternal cloacal opening.

Trophic ecology of a tropical aquatic and terrestrial food web: insights from stable isotopes ( 15 N)

Weusedstableisotopeanalysis( 15 N/ 14 N)tocharacterizethetrophicrelationshipsofconsumercommunities of an aquatic food web (a permanent pond) and the adjacent terrestrial food web (secondary dry dipterocarp forest) fromaseasonaltropicalfieldsiteinnorth-easternThailand.Ingeneral, isotopicsignaturesofaquaticvertebrates were higher (δ 15 N range =4.51-9.90‰) than those of invertebrates (δ 15 N range =1.10-6.00‰). High 15 N signatures identifiedwatersnakesandswampeelsastoppredatorsinthepondfoodweb.Intheterrestrialfoodweb 15 Nsignatures ofsaprophagouslitterinvertebrates(diplopods,earthworms),termites,antsandbeetlelarvaewerelowerthaninthose ofpredatoryinvertebrates(scolopendrids,scorpions,whipspiders).Predatoryterrestrialfrogsandcaecilianshadlower 15 N signatures than snakes, indicating that snakes are among the top predators in the terrestrial web. Based on the distribution of isotopic signatures, we estimated five trophic levels for both the aquatic and terrestrial food web. The foodchainsofaseasonaltropicalsitestudiedwererathershort,whichimpliessimilaritiestothestructureoftemperate food webs.

Life history of amphibians in the seasonal tropics: habitat, community and population ecology of a caecilian (genus Ichthyophis)

Fundamental information on the ecology of the limbless tropical caecilians is needed for a well-founded conservation assessment. Here, essential life-history characters are presented for the oviparous caecilian Ichthyophis cf. kohtaoensis from a field site in South-east Asia (Mekong valley, north-eastern Thailand).Ichthyophis cf.kohtaoensis was found in a range of terrestrial macrohabitats including open scrubs, gallery forests and open secondary dipterocarp forests. In the dry season, caecilians were found mainly in soil but in the rainy season they were also detected in epigeic microhabitats (leaf litter or rotten vegetation). Ichthyophis cf. kohtaoensis were recorded in low densities (median 0.08 individuals/m 2 ) and they share their habitat with a range of other terrestrial amphibians and reptiles. The population structure of I. cf. kohtaoensis varied seasonally. Records of late metamorphs were restricted to the cold dry season and occasionally to the onset of the rainy season. Females with clutches were only found in the rainy season. A life-history scenario of I. cf. kohtaoensis in north-eastern Thailand was set up. Reproduction and larval development is related to the rainy season. Mating and oviposition may start at the onset of the monsoon. Larvae hatch at the peak until the end of the rainy season and metamorphose until the end of the dry season. In the light of amphibian decline, this study may encourage further baseline work on the ecology of other caecilian species.

Phylotranscriptomic consolidation of the jawed vertebrate timetree

Phylogenomics is extremely powerful but introduces new challenges as no agreement exists on ‘standards’ for data selection, curation and tree inference. We use jawed vertebrates (Gnathostomata) as a model to address these issues. Despite considerable efforts in resolving their evolutionary history and macroevolution, few studies have included a full phylogenetic diversity of gnathostomes, and some relationships remain controversial. We tested a new bioinformatic pipeline to assemble large and accurate phylogenomic datasets from RNA sequencing and found this phylotranscriptomic approach to be successful and highly cost-effective. Increased sequencing effort up to about 10 Gbp allows more genes to be recovered, but shallower sequencing (1.5 Gbp) is sufficient to obtain thousands of full-length orthologous transcripts. We reconstruct a robust and strongly supported timetree of jawed vertebrates using 7,189 nuclear genes from 100 taxa, including 23 new transcriptomes from previously unsampled key species. Gene jackknifing of genomic data corroborates the robustness of our tree and allows calculating genome-wide divergence times by overcoming gene sampling bias. Mitochondrial genomes prove insufficient to resolve the deepest relationships because of limited signal and among-lineage rate heterogeneity. Our analyses emphasize the importance of large, curated, nuclear datasets to increase the accuracy of phylogenomics and provide a reference framework for the evolutionary history of jawed vertebrates.The use of genomic data to reconstruct phylogenetic relationships is powerful but challenging. Here, the authors develop a bioinformatics pipeline and use phylogenomic datasets to reconstruct the evolutionary relationships of jawed vertebrates.

On the taxonomy of ichthyophiid caecilians from southern Thailand: A reevaluation of the holotype of Ichthyophis supachaii Taylor 1960 (Amphibia: Gymnophiona: Ichthyophiidae)

The taxonomy of South-East Asian ichthyophiid caecilians is largely in a woeful state. We give a new diagnosis for Ichthyophis supachaii from Thailand, based on a reexamination of the complete type series and recently collected material. The holotype is redescribed. The higher number of splenial than dentary teeth, a previously reported main diagnostic character of the taxon, is rejected. Ichthyophis supachaii follows the usual pattern of ichthyophiid caecilians in having more dentary than splenial teeth. Nevertheless, Ichthyophis supachaii is regarded as a valid taxon based on several morphometric and meristic characters. We provide a detailed description of the male phallodeum.

Care and Parentage in a Skin-Feeding Caecilian Amphibian

An exceptional form of parental care has recently been discovered in a poorly known caecilian amphibian. Mothers of the Taita Hills (Kenya) endemic Boulengerula taitanus provide their own skin as a food source for their offspring. Field data suggest that nursing is costly. Females found attending young had a lower body condition and fat body volume than nonbrooding and egg-incubating females, and the female condition decreased substantially during parental care. Most mothers and their eggs or offspring were found in close proximity to other nesting females, in high-density nest sites that enhance the potential for social interactions and highlighting the possibility of communal breeding. Parentage was investigated using Amplified Fragment Length Polymorphism (AFLP) genetic markers in 29 offspring from six litters guarded by putative mothers. Our data provide the first evidence of multiple paternity in a caecilian, implying that two fathers sired one litter. Some young from two litters had genotypes not matching the guarding female suggesting that not all offspring are cared for by their biological mothers. This study provides evidence for alloparenting in an amphibian with cost-intensive parental care.

Passive trapping of aquatic caecilians (Amphibia: Gymnophiona: Typhlonectidae)

Abstract Due to a paucity of quantitative methods to study caecilian amphibians, knowledge of their biology has lagged far behind that of other neotropical vertebrates. We report the passive trapping of the aquatic Typhlonectes compressicauda (Typhlonectidae) from a pond in French Guiana. Four collapsible, nylon-meshed funnel traps (two different manufacturers) were baited with fish and set over a total of five nights in June 2004 and January 2005. A total of 11 T. compressicauda were collected across four nights, all in the same single trap. Our results demonstrate the feasibility of passive trapping of aquatic caecilians. This method of capture provides study specimens, but also has the potential to yield quantitative data on the population biology of these poorly known amphibians.

Flesh and bone: An integrative approach towards sexual size dimorphism of a terrestrial salamander (genus Salamandrina)

Males and females face different selection pressures due to a sexually biased investment into reproduction. This often results in different morphologies. Sexual size dimorphisms (SSD) can give us important hints on the evolution and biology of a species. Salamanders are a perfectly suited system for investigating SSD, including a diversity of reproductive modes and behaviors, and patterns of SSD combined with life history traits in a phylogenetic context help us to understand the evolution of these processes. Because spectacled salamanders (genus Salamandrina) are the phylogenetically most basal taxon of the Salamandridae, they play a key role in reconstructing the evolutionary pattern of SSD. Combining extensive external and skeletal measurements of the cranium, limbs, and the pelvic girdle using high‐resolution micro Computer Tomography (μCT) yielded an integrative analysis of expressed SSD of morphology and osteology of Salamandrina perspicillata. Multivariate analysis of external characters showed that males generally had larger cloacae, heads, and limbs relative to body size, while females had larger trunks. Analysis of osteology confirmed this pattern but also revealed new dimorphic characters in the cranium and the pelvic girdle. Dimorphic characters in external morphology and osteology are likely linked to the different reproductive roles of the sexes and support sexual rather than ecological selection as the primary force acting on the phenotype of the phylogenetically basal salamandrids.