Molecular evidence regarding the origin of echolocation and flight in bats

Bats (order Chiroptera) are one of the few orders of mammals that echolocate and the only group with the capacity for powered flight. The order is subdivided into Microchiroptera and Megachiroptera, with an array of characteristics defining each group, including complex laryngeal echolocation systems in microbats and enhanced visual acuity in megabats. The respective monophylies of the two suborders have been tacitly assumed, although microbat monophyly is uncorroborated by molecular data. Here we present a phylogenetic analysis of bat relationships using DNA sequence data from four nuclear genes and three mitochondrial genes (total of 8,230 base pairs), indicating that microbat families in the superfamily Rhinolophoidea are more closely related to megabats than they are to other microbats. This implies that echolocation systems either evolved independently in rhinolophoids and other microbats or were lost in the evolution of megabats. Our data also reject flying lemur (order Dermoptera) as the bat sister group, indicating that presumed shared derived characters for flying lemurs and bats are convergent features that evolved in association with gliding and flight, respectively.     

Symbiosis insights through metagenomic analysis of a microbial consortium

Symbioses between bacteria and eukaryotes are ubiquitous, yet our understanding of the interactions driving these associations is hampered by our inability to cultivate most host-associated microbes. Here we use a metagenomic approach to describe four co-occurring symbionts from the marine oligochaete Olavius algarvensis, a worm lacking a mouth, gut and nephridia. Shotgun sequencing and metabolic pathway reconstruction revealed that the symbionts are sulphur-oxidizing and sulphate-reducing bacteria, all of which are capable of carbon fixation, thus providing the host with multiple sources of nutrition. Molecular evidence for the uptake and recycling of worm waste products by the symbionts suggests how the worm could eliminate its excretory system, an adaptation unique among annelid worms. We propose a model that describes how the versatile metabolism within this symbiotic consortium provides the host with an optimal energy supply as it shuttles between the upper oxic and lower anoxic coastal sediments that it inhabits.