Justin Gerlach | University of Cambridge (original) (raw)
I have worked in conservation, ecology and evolution for 30 years, supported with a living made from undergraduate teaching and from scientific books.
My recent focus has been the Partula snails. I worked on them 20 years ago and now come to their fascinating evolution and tragic demise with new perspectives. My recent work resulted in a major monograph of the family Partulidae (http://islandbiodiversity.com/partulapages.htm). I am also working on the predators that affect these snails.
I am developing new collaborative research on the biodiversity of Madagascar and on the recently discovered remarkable behaviour of hunting by giant tortoises.
Address: Peterhouse, Cambridge, United Kingdom
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Papers by Justin Gerlach
Current Biology, 2021
Tortoises (land turtles) are familiar animals and are generally assumed to be strict herbivores. ... more Tortoises (land turtles) are familiar animals and are generally assumed to be strict herbivores. Their ecological roles are most obvious in giant tortoise species which, due to their size and local abundance, play major roles as keystone species and ecosystem engineers. In the Galápagos and Seychelles islands these species are known to play major roles as the islands’ largest herbivores, with exceptionally high biomass and consuming up to 11% of primary production1. In addition they act as ecosystem engineers, dispersing seeds, breaking vegetation and eroding rocks2. However, as slow-moving poikilotherms most people assume their behaviour to be simple. Here we present video evidence of a Seychelles giant tortoise (Aldabrachelys gigantea) attacking a tern chick and pursuing it along a log. Finally the tortoise killed the chick and was observed to eat it. Other tortoises in the same area have been seen making similar attacks, although those were not fully documented. We believe that the exceptional combination of a tree-nesting tern colony with a resident giant tortoise population has created conditions leading to systematic hunting of birds by several individual tortoises; an entirely novel behavioural strategy for any tortoise species.
Nature Ecology & Evolution, 2020
Phelsuma, 1996
Page 1. The effects of habitat domination by invasive Melastomataceae Justin Gerlach, PO Box 207,... more Page 1. The effects of habitat domination by invasive Melastomataceae Justin Gerlach, PO Box 207, Victoria, Mané, SEYCHELLES. ... Leaf litter was collected from 10m2 and animals extracted using a Winkler apparatus in December 1993. ...
Scripta Botanica Belgica, 2010
The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have lo... more The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have long focused on taxonomy, and plant communities were described in a qualitative way, based on simple observation. Therefore the altitudinal belts, their floristic characteristics and distribution are still poorly understood and conservation efforts focus mainly on species-centred actions. Here we describe a quantitative study of plant communities and indicator species differentiated along the altitudinal gradient on Silhouette, the most pristine and second highest (740 m) island of this archipelago. Twelve plots were sampled from 80 m to 640 m above sea level. Each plot contains three nested subplots corresponding to three forest strata. Three altitudinal belts are distinguished: lowland, submontane and lower montane rain forests. Most of the best indicator species are found in the understory, especially ferns. The submontane belt develops at about 350 m and turns into a typical lower mont...
Conservation Biology of Freshwater Turtles and Tortoises, 2008
IOP Conf. Ser.: Earth Environ. Sci., 2009
ABSTRACT This article was submitted without an abstract, please refer to the full-text PDF file.
Journal of Threatened Taxa, 2013
Chelonian Conservation and Biology, 2013
Chelonian Conservation and Biology, 2011
SCIENCE-NEW YORK THEN WASHINGTON-, 2006
Report on a visit to the Bishop Museum, Hawaii to examine their amazing collection of Partula sna... more Report on a visit to the Bishop Museum, Hawaii to examine their amazing collection of Partula snails. Partula taxonomy now almost completely worked out. http://islandbidoversity.com/pnews.htm
Current Biology, 2021
Tortoises (land turtles) are familiar animals and are generally assumed to be strict herbivores. ... more Tortoises (land turtles) are familiar animals and are generally assumed to be strict herbivores. Their ecological roles are most obvious in giant tortoise species which, due to their size and local abundance, play major roles as keystone species and ecosystem engineers. In the Galápagos and Seychelles islands these species are known to play major roles as the islands’ largest herbivores, with exceptionally high biomass and consuming up to 11% of primary production1. In addition they act as ecosystem engineers, dispersing seeds, breaking vegetation and eroding rocks2. However, as slow-moving poikilotherms most people assume their behaviour to be simple. Here we present video evidence of a Seychelles giant tortoise (Aldabrachelys gigantea) attacking a tern chick and pursuing it along a log. Finally the tortoise killed the chick and was observed to eat it. Other tortoises in the same area have been seen making similar attacks, although those were not fully documented. We believe that the exceptional combination of a tree-nesting tern colony with a resident giant tortoise population has created conditions leading to systematic hunting of birds by several individual tortoises; an entirely novel behavioural strategy for any tortoise species.
Nature Ecology & Evolution, 2020
Phelsuma, 1996
Page 1. The effects of habitat domination by invasive Melastomataceae Justin Gerlach, PO Box 207,... more Page 1. The effects of habitat domination by invasive Melastomataceae Justin Gerlach, PO Box 207, Victoria, Mané, SEYCHELLES. ... Leaf litter was collected from 10m2 and animals extracted using a Winkler apparatus in December 1993. ...
Scripta Botanica Belgica, 2010
The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have lo... more The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have long focused on taxonomy, and plant communities were described in a qualitative way, based on simple observation. Therefore the altitudinal belts, their floristic characteristics and distribution are still poorly understood and conservation efforts focus mainly on species-centred actions. Here we describe a quantitative study of plant communities and indicator species differentiated along the altitudinal gradient on Silhouette, the most pristine and second highest (740 m) island of this archipelago. Twelve plots were sampled from 80 m to 640 m above sea level. Each plot contains three nested subplots corresponding to three forest strata. Three altitudinal belts are distinguished: lowland, submontane and lower montane rain forests. Most of the best indicator species are found in the understory, especially ferns. The submontane belt develops at about 350 m and turns into a typical lower mont...
Conservation Biology of Freshwater Turtles and Tortoises, 2008
IOP Conf. Ser.: Earth Environ. Sci., 2009
ABSTRACT This article was submitted without an abstract, please refer to the full-text PDF file.
Journal of Threatened Taxa, 2013
Chelonian Conservation and Biology, 2013
Chelonian Conservation and Biology, 2011
SCIENCE-NEW YORK THEN WASHINGTON-, 2006
Report on a visit to the Bishop Museum, Hawaii to examine their amazing collection of Partula sna... more Report on a visit to the Bishop Museum, Hawaii to examine their amazing collection of Partula snails. Partula taxonomy now almost completely worked out. http://islandbidoversity.com/pnews.htm
The partulid tree-snails of the Pacific Islands are today best known for their tragic recent hist... more The partulid tree-snails of the Pacific Islands are today best known for their tragic recent history. Following the introduction of predatory snails a third of partulid species are now extinct and almost all others threatened with extinction. As most of these extinctions took place in a 20 year period this is one of the most dramatic rates of extinction ever recorded. Before Partula became icons of extinction, they were central to the development of our understanding of evolutionary biology. This started with the pioneering field studies of evolution by Henry Crampton in 1908 and led to laboratory genetics studies of the inheritance of genetic traits. Crampton's great work on Partula was unfinished by the time of his death. This book marks the centenary of the publication of Crampton's first volume by completing his work, and updates it with a full revision of the taxonomy, and comprehensive accounts of what is known of the history, ecology, evolution and conservation of the family. This revision consolidates the 344 names applied to the family into 103 species, including the description of 5 new species. Each valid species is described with full references and synonyms, distribution maps, and photographs of 842 shells: type specimens of each species and all colour varieties. This is based on measurements of 125,824 shells, dissections of 1,244 snails and the analysis of 30 years of data from the captive breeding programme.
The islands of the Western Indian Ocean (Madagascar and the small island groups of the Seychelles... more The islands of the Western Indian Ocean (Madagascar and the small island groups of the Seychelles, Mascarenes and Comoros) are home to a remarkable diversity of animals and plants. Among the most notable are the tortoises, including some of the world’s largest, smallest and rarest species. Historically, at least ten species were present in the islands but today only five survive. This book reviews all of the information on the species, drawing together the historical records (many previously unpublished) including how humans decimated the tortoise populations as a source of food for long sea voyages, along with the latest information on palaeontology, evolution and ecology, including from a molecular genetics perspective. The conservation status of each species is described, as are the current efforts to restore tortoises to their central position in the ecology of these islands. The volume includes contributions from twelve expert authors from the UK, France, USA, Canada and Madagascar
The story of the tree snails of the Pacific Islands spans 250 years of the history of biology as ... more The story of the tree snails of the Pacific Islands spans 250 years of the history of biology as a science. This runs from Captain Cook's first voyage of exploration, through the start of evolutionary theory and the development of the science of genetics. 'Snailing round the South Seas' traces this history through the surprisingly central role played by a group of snails. Ultimately this leads into the struggle for survival in the modern world. Partula snails almost disappeared in the most rapid extinction event known so far and the survivors are among the rarest species on earth. Once more these snails have been at the heart of new developments, this time in conservation biology.
Brief summary of research work in the collections of the Academy of Natural Sciences, Philadelphia
