Champions of biodiversity: A weevil genus beats records of explosive evolutive radiation

With as many as 120 recently discovered weevils placed in the genus Laparocerus, it now hosts a total of 237 known species and subspecies. They are all flightless beetles and most of them endemic (living exclusively in one geographic location) to a single island of the archipelagos of Madeira, Selvagens and the Canary Islands (17 islands in total). Only two species inhabit Morocco, the nearest continental land.

Independent Canarian entomologist Dr. Antonio Machado, who has been collecting and studying this genus of weevils for the last sixteen years and researched 46,500 specimens so far, was helped by geneticist Dr. Mariano Hernández, from the University of La Laguna, Tenerife, Canary Islands, Spain, to undertake a phylogenetic study using three mitochondrial genes and one nuclear gene. The resulting phylogenetic tree also allowed for estimating the whole evolutionary process along a timeframe of about 11.2 million years. Their study is published in the open access journal ZooKeys.

The molecular analysis confirms that all Laparocerus weevils have a common evolutionary ancestor (monophyly), but could not clarify whether that ancient founding species arrived from southern Europe or northwestern Africa. The two extant Moroccan species were found to be the result of a back-colonisation from the Canary Islands to Africa, and not the ancestral source lineage, which unfortunately is still unknown.

weevils PR 2Colonisation of Macaronesia started in Porto Santo, Madeiran archipelago, which is the oldest island, and from there it ‘jumped’ to Madeira and the Desertas. The colonisation of the Canary Islands started shortly after, and it basically moved stepwise from the east to the west in line with the decreasing age of the volcanic islands. Yet, there have been several back-colonisations, as well (see map). Large islands, such as Tenerife (2034 km2), ended up with 65 species and subspecies. Globally, there is an outstanding ratio of one endemic Laparocerus for each 35.7 km2; a record not beaten by any other genus of plant or animal in Macaronesia.

The evolutionary process responsible for such richness comprises sequential radiation events in these archipelagoes, each generating several monophyletic groups. These groups, 20 in total, have been recognised as subgenera of Laparocerus, and five of them — Aridotrox, Belicarius, Bencomius, Canariotrox, and Purpuranius — are described as new to science in this study. Colonisation routes, habitat shifts, disruption of populations by volcanism, dispersal by massive landslides, and other relevant aspects for adaptive and non-adaptive radiation, are largely discussed and confronted with previously published data referring to other groups of beetles or to other biological organisms (spiders, bush crickets, plants, etc.).

“If oceanic islands have been traditionally considered as laboratories of evolution and species-producing machines, Laparocerus will become the ideal guinea-pig for broadening studies in dispersal and speciation processes of all kinds,” say the authors. “Working with such a group is like getting a picture of Nature with more pixels. Several intriguing cases highlighted in this contribution may turn into the inspiration for further phylogeographic research.”

The scientists hope that, in near future Laparocerus will merit sharing the podium with Darwin´s finches or Drosophila in the studies of island evolution”.

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Original source:

Machado A, Rodríguez-Expósito E, López M, Hernández M (2017) Phylogenetic analysis of the genus Laparocerus, with comments on colonisation and diversification in Macaronesia (Coleoptera, Curculionidae, Entiminae). Zookeys 651: 1-77 (02 Feb 2017) https://doi.org/10.3897/zookeys.651.10097

South African endemic mountain plant gives itself up after 147-year absence

South Africa’s mountains are essential to the economic well-being of the country, providing many goods and services essential for social and economic prosperity. However, the biodiversity value of these mountains is still poorly understood. This is exemplified by the large number of plant species still only known from one or two collections made well over a century ago.

The Great Escarpment Biodiversity Research Programme, led by Prof. Nigel Barker, University of Pretoria, has been systematically documenting plant diversity and endemism along much of the Great Escarpment – southern Africa’s principal mountain system.

“This ‘un-sexy’ foot-slogging research has yielded a number of valuable discoveries and rediscoveries, highlighting the biodiversity value of these mountains,” points lead author Dr Ralph Clark, Rhodes University, South Aftica.

One of these rediscoveries is a plant last seen only by one more person: Mrs Elizabeth Barber, one of South Africa’s finest women botanists of the 19th century. Mrs Barber has been a regular correspondent with Charles Darwin and has provided material of South African plants to numerous institutions in Europe.

“Her discovery – Lotononis harveyi, also known under the common name ‘Mrs Barber’s Beauty’ in her honour, was published in 1862, but unfortunately, as her specimen did not include a date, we do not know the actual year in which she discovered it,” he explains. “What we do know, is that it mysteriously disappeared for at least 147 years, despite attempts to relocate it.”harveyi img2

In 2009, Dr Ralph Clark undertook an extensive collecting trip to the Great Winterberg, where he accidently stumbled across a flowering specimen of ‘Mrs Barber’s Beauty’. It was only in 2014, however, that the plant was properly recognised for what it was, and a second trip was quickly planned.

The results of the second trip included the first photographs and ecological records of this apparently scarce species. Dr Clark’s results have been published in the open access journal PhytoKeys.

“There are currently only six known individuals of this species. The main limiting factors appear to be fire and grazing, the plants only occurring where these two prominent ecological actors have been excluded for some time,” notes Dr Clark.

“However, with much of these mountains still poorly explored by biodiversity scientists, it is possible that additional individuals will come to light. For now the species will be regarded as Critically Endangered.”

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Original source:

Clark VR, Bentley J, Dold AP, Zikishe V, Barker NP (2016) The rediscovery of the Great Winterberg endemic Lotononis harveyi B.-E.van Wyk after 147 years, and notes on the poorly known Amathole endemic Macowania revolutaOliv. (southern Great Escarpment, South Africa). PhytoKeys 62: 1-13. doi: 10.3897/phytokeys.62.8348