It's another stunning Malagasy #dartfrog/#poisonfrog for today's #FrogOfTheDay, #42 Mantella cowani Boulenger, 1882! A highly threatened, actively conserved and managed frog from the highlands of central #Madagascar
#MadagascarFrogs
📸D.Edmonds/CalPhotos

This thread will cover only a tiny fraction of the work on Mantella cowanii because, being so charismatic and threatened, it has received quite a bit of attention.
#MadagascarFrogs
We start at the very beginning: the first specimens, two females, were collected by Reverend Deans Cowan in East Betsileo, Madagascar, and sent to London, where George Albert Boulenger described the species in 1882.
#MadagascarFrogs
Boulenger placed the species in his new genus, Mantella, along with ebenaui, betsileo, and madagascariensis. He recognised that the other Malagasy poison frogs were distinct from the Dendrobates of the Americas, although he did keep them in the Dendrobatidae.
#MadagascarFrogs
As more specimens were collected, it became clear that the species was highly variable. In 1978, Jean Guibé wrote with interest about this variability, describing a new subspecies, M. cowani nigricans—today a full species. #MadagascarFrogs
https://t.co/dwaHMbrYbj
Although Guibé was wrong about the affinities of those two species, it is true that there is astounding variability of colour in this (and other) Mantella species, and that they evidently hybridise with other species.
#MadagascarFrogs
📸B.Freiermuth/CalPhotos
Little was known about Mantella cowanii in the wild until the 1990s. By 1999, when Miguel Vences et al. published a revision of Mantella, it was known from a few different locations, but populations between it and M. baroni posed challenges to identification.
#MadagascarFrogs
These frogs occur in bizarre habitat in central Madagascar, often with wet, exposed rocks interspersed with low bushes.
📸Mantella cowanii Action Plan, 2021–2025 (on which more below)
The first (?) DNA-based phylogeny came out in 2002, confirming close affinity with M. baroni and M. nigricans, and showing that Malagasy poison frogs may have Müllerian mimicry generating repeated colour pattern evolution. https://t.co/4qqzbiiAev
#MadagascarFrogs
The hybridisation of M. cowanii with M. baroni received a lot of interest, in part because the species are generally morphologically and ecologically distinct.
https://t.co/VMFGZ7tP0Y
https://t.co/9uFZ7KBRzZ
International interest has always been strong in the beautiful #Mantella #frogs, so M. cowanii were targeted for the pet trade. Between 1988 and 2003, some 12,877 individuals were reportedly exported from Madagascar.
https://t.co/gJXip5xMTv
#MadagascarFrogs
In 2005, @CITES imposed a zero quota on M. cowanii, effectively banning export. For a species known from only a few locations in threatened habitat, and low fecundity (Tessa et al., see link), harvesting at these rates was unsustainable.
#MadagascarFrogs
https://t.co/SAON3F2VqF
Until 2014, Mantella cowanii was listed as Critically Endangered, but it was then downgraded to Endangered. Apparently the population declines seen until 2003 were halted by the cessation of trade. https://t.co/2rS29qFNQT
#MadagascarFrogs
Nevertheless, Mantella cowanii is heavily threatened. Representatives of @ASG_IUCN @Voakajy @amphibiansorg @chesterzoo and other organisations are actively involved in its conservation. A new action plan for 2021–2025 was just released.
#MadagascarFrogs
https://t.co/ozm89CMSSR
As I understand it, captive populations of Mantella cowanii are being maintained. So, if extirpated, it might be possible to reintroduce this frog, as long as habitat remains available. So there is hope for the 'harlequin' mantella!
#MadagascarFrogs

More from Science

Hard agree. And if this is useful, let me share something that often gets omitted (not by @kakape).

Variants always emerge, & are not good or bad, but expected. The challenge is figuring out which variants are bad, and that can't be done with sequence alone.


You can't just look at a sequence and say, "Aha! A mutation in spike. This must be more transmissible or can evade antibody neutralization." Sure, we can use computational models to try and predict the functional consequence of a given mutation, but models are often wrong.

The virus acquires mutations randomly every time it replicates. Many mutations don't change the virus at all. Others may change it in a way that have no consequences for human transmission or disease. But you can't tell just looking at sequence alone.

In order to determine the functional impact of a mutation, you need to actually do experiments. You can look at some effects in cell culture, but to address questions relating to transmission or disease, you have to use animal models.

The reason people were concerned initially about B.1.1.7 is because of epidemiological evidence showing that it rapidly became dominant in one area. More rapidly that could be explained unless it had some kind of advantage that allowed it to outcompete other circulating variants.

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