Many chameleons, and panther chameleons in particular, have the remarkable ability to exhibit complex and rapid colour changes during social interactions such as male contests or courtship. It is generally interpreted that these changes are due to dispersion/aggregation of pigment-containing organelles within dermal chromatophores. Here, combining microscopy, photometric videography and photonic band-gap modelling, we show that chameleons shift colour through active tuning of a lattice of guanine nanocrystals within a superficial thick layer of dermal iridophores. In addition, we show that a deeper population of iridophores with larger crystals reflects a substantial proportion of sunlight especially in the near-infrared range. The organization of iridophores into two superposed layers constitutes an evolutionary novelty for chameleons, which allows some species to combine efficient camouflage with spectacular display, while potentially providing passive thermal protection.

Recent studies have reported that independent adaptive radiations can lead to identical ecomorphs. Our phylogenetic analyses of nuclear and mitochondrial DNA sequences here indicate that a major radiation of ranid frogs on Madagascar produced morphological, physiological, and developmental characters that are remarkably similar to those that independently evolved on the Indian subcontinent. We demonstrate further that, in several cases, adult and larval stages each evolved sets of characters which are not only convergent between independent lineages, but also allowed both developmental stages to invade the same adaptive zone. It is likely that such covariations are produced by similar selective pressures on independent larval and adult characters rather than by genetic or functional linkage. We briefly discuss why larval/adult covariations might constitute an important evolutionary phenomenon in species for which more than one developmental stage potentially has access to multiple environmental conditions.

The apparent biotic affinities between the mainland and the island in the Western Ghats–Sri Lanka biodiversity hotspot have been interpreted as the result of frequent migrations during recent periods of low sea level. We show, using molecular phylogenies of two invertebrate and four vertebrate groups, that biotic interchange between these areas has been much more limited than hitherto assumed. Despite several extended periods of land connection during the past 500,000 years, Sri Lanka has maintained a fauna that is largely distinct from that of the Indian mainland. Future conservation programs for the subcontinent should take into account such patterns of local endemism at the finest scale at which they may occur.

Ranidae is a large anuran group with a nearly cosmopolitan distribution. We investigated the phylogenetic relationships and early biogeographic history of ranid frogs, using 104 representatives of all subfamilies and families, sampled from throughout their distribution. Analyses of ∼ 1570 bp of nuclear gene fragments (Rag-1, rhod, Tyr) and ∼ 2100 bp of the mitochondrial genome (12S rRNA, tRNA^VAL, 16S rRNA) indicate that the monophyly of several taxa can be rejected with high confidence. Our tree is characterized by a clear historical association of each major clade with one Gondwanan plate. This prevalence of continent-scale endemism suggests that plate tectonics has played a major role in the distribution of ranid frogs. We performed dispersal-vicariance analyses, as well as analyses constrained by paleogeographic data, to estimate ancestral distributions during early ranid diversification. Additionally, we used molecular clock analyses to evaluate whether these scenarios fit the temporal framework of continental breakup. Our analyses suggest that a scenario in which the ancestors of several clades (Rhacophorinae, Dicroglossinae, Raninae) reached Eurasia via the Indian subcontinent, and the ancestor of Ceratobatrachinae entered via the Australia–New Guinea plate, best fits the paleogeographic models and requires the fewest number of dispersal/vicariance events. However, several alternatives, in which part of the ranid fauna colonized Laurasia from Africa, are not significantly worse. Most importantly, all hypotheses make clear predictions as to where to expect key fossils and where to sample other living ranids, and thus constitute a strong basis for further research.

Sixty-five million years ago, massive volcanism produced on the India-Seychelles landmass the largest continental lava deposit (Deccan Traps) of the past 200 million years. Using a molecular clock–independent approach for inferring dating information from molecular phylogenies, we show that multiple lineages of frogs survived Deccan Traps volcanism after millions of years of isolation on drifting India. The collision between the Indian and Eurasian plates was followed by wide dispersal of several of these lineages. This “out-of-India” scenario reveals a zoogeographical pattern that might reconcile paleontological and molecular data in other vertebrate groups.