Aye-aye captain

Perhaps one of the most peculiar species of primates, the aye-aye (Daubentonia madagascariensis) is a nocturnal, arboreal insectivore is found only in Madagascar. It is believed that the common name for this species came from the "exclaim of surprise and astonishment" by the French naturalist Pierre Sonnerat at the sight of the animal. However, it was later pointed out that the name is quite similar to the Malagasy name for the animal "hai hai" [1].

Aye-aye by nomis-simon, [CC BY 2.0], via wikimedia.org

Aye-ayes spend the majority of their lives in solitude in the canopies of the forests. The most notable characteristic of the aye-aye is their long, skeletal middle finger which is used to tap into trees to unearth larvae using a method called "tap foraging". The aye-aye is the only primate to use echo-location, and it's middle digit serves as it's primary sensory organ. Their odd appearance may have contributed to the superstition by some natives of Madagascar that they are an incredibly unlucky omen. Unfortunately this has led to many being killed onsite [3]. Coupled with deforestasion this has led to the aye-aye becoming endangered (see IUCN).

Today we share the genome assembly for the aye-aye, Daubentonia madagascariensis. This is a $1K genome assembly, with a contig N50 = 215 Kb and a scaffold N50 = 211 Mb. For assembly procedure details, please see our Methods page. We graciously thank the Duke Lemur Center for providing the sample used to generate this chromosome-length assembly. Please check out the interactive Juicbox.js session below to explore the 15 chromosomes of the aye-aye:

Upon its initial classification, the aye-aye was believed to be a kind of rodent. This was a understandable presumption, as the aye-aye has ever growing incisors that are characteristic of the order Rodentia. Their cat-like face also led to some debate whether the aye-aye should be a a felid. Eventually, it was established that aye-ayes are lemurs! For some preliminary analysis, we aligned the new chromosome-length aye-aye reference, Daubentonia_madagascariensis_HiC (2n=30) against the collared lemur assembly Eulemur_collaris_HiC (2n=50), see the dot plot below. There are a large number of rearrangements between the two genomes underlying the different chromosome count.

Whole genome alignment plot between the aye-aye, (Daubentonia_madagascariensis_HiC) (2n=30) against the collared lemur, (Eulemur_collaris_HiC).

We're not monkeying around here, this is the 6th Lemuroidea species we've released so far and the 20th primate overall! Check out these other $1K assemblies for the Guinea baboon (P. papio), the golden lion tamarin (L. rosalia), and the Patas monkey (E. patas). Remember to follow us on Twitter @thednazoo and subscribe to our mailing list below to keep up to date on our latest releases!

Banding together

Unlike most other mongoose species, the banded mongoose, Mungos mungo, are social and prefer to band together. They live in groups of 10-20 individuals but may live in communities as large as 40 mongooses. As they are also smaller in size than other mongoose species, these groups may provide more protection. When a group of banded mongooses are approached by a predator, they group together to try and create the appearance of a larger, singular animal to intimidate the threat [1].

Banded mongoose by Cloudtail, [CC BY-NC-ND 2.0], via flickr.com

Today, we release the chromosome-length assembly for the banded mongoose, Mungos mungo! This is another $1K genome assembly, with contig n50 = 61 Kb and scaffold n50 = 129 Mb. We'd like to thank Fupi, a female banded mongoose from the Houston Zoo for donating the sample used to generate is assembly! Check out the interactive JuiceBox.js session below:

If you're interested in more assemblies from the Herpestidae family, check out our chromosome-length upgrade for the meerkat, Suricata suricatta. As always, we recommend subscribing to our mailing list below to keep up to date on our latest releases! Check back weekly for more chromosome-length genomes.

Congratulations! It's a... dragon?

The central bearded dragon (Pogona vitticeps) is a species of lizard with a flattened body, entirely covered by specialized scales. These lizards got their name due to their ability of making their throat look like a beard by inflating and puffing it out as well as the ability of their throat to turn to black when threatened.

Photo Description – The Central bearded dragon (Pogona vitticeps). Photo credits: David Cook [Public domain], via flickr.com

The central bearded dragon is an opportunistic omnivore widely distributed over eastern and central parts of Australia, found from the southeastern Northern Territory to the eastern part of southern Australia. They live in very diverse habitats including desert, dry forests and scrublands. Normally, these animals are diurnal. The central bearded dragon is an excellent climber, often found perched in bushes as well as on branches of trees and fence posts, spending as much time perching as it does on the ground. They are not social animals, though sometimes they congregate into groups to feed and bask.

Today we share a chromosome-length genome assembly for the central bearded dragon based on a draft assembly by Georges et al. GigaScience (2015). This draft was scaffolded with data donated by Norman, a central bearded dragon from Houston Zoo. Check out the interactive Hi-C contact map for the 16 chromosomes of the central bearded dragon below!

Central bearded dragon is one of the only two species of squamates (scaled reptiles) that has what's called genetic sex determination with overriding thermal influence (the other one being the eastern three-linked skink). (The lack of species with unambiguously identified sex reversal is not necessarily a reflection of this being a rare trait among reptiles as it is difficult to detect and document.) A study in 2015 has demonstrated that when eggs are incubated at temperatures above 32 °C (90 °F) some genetic males are born female! (1)

We hope that improvements to the bearded dragon reference genome assembly will improve genomic resources available for studying sex reversal in the species, help explore its prevalence and evolutionary implications in the current climate change landscape of rising temperatures.

Citations

Holleley CE, O'Meally D, Sarre SD, Graves JAM, Ezaz T, Matsubara K, Azad B, Zhang X, Georges A. (2015). "Sex reversal triggers the rapid transition from genetic to temperature-dependent sex". Nature. 523 (7558): 79‒82. doi:10.1038/nature14574