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Expert-Driven Distribution Modelling: Identifying Habitat for Eresus sandaliatus in Scania

Gerell, Dan (2017) BIOM01 20171
Degree Projects in Biology
Abstract
Landscape fragmentation and habitat loss are detrimental to biodiversity, affecting highly specialised species the most. Species distribution models usually require either solid knowledge about the ecological niche of the species or spatial distribution data. Many endangered species have, how- ever, a relatively unexplored ecological niche in combination with a very small area of distribution. A method identifying habitat for such a species was devised and applied on the endangered spider Eresus sandaliatus that is known from only a single locality in Sweden. A prediction model was built using a combination of literature research and expert knowledge about the species’ habitat requirements. The model was tested and calibrated using spatial... (More)
Landscape fragmentation and habitat loss are detrimental to biodiversity, affecting highly specialised species the most. Species distribution models usually require either solid knowledge about the ecological niche of the species or spatial distribution data. Many endangered species have, how- ever, a relatively unexplored ecological niche in combination with a very small area of distribution. A method identifying habitat for such a species was devised and applied on the endangered spider Eresus sandaliatus that is known from only a single locality in Sweden. A prediction model was built using a combination of literature research and expert knowledge about the species’ habitat requirements. The model was tested and calibrated using spatial records of known populations in a neighbouring region. The post-calibration model was applied to Scania and several suitable areas could be identified through a field survey of top predictions made by the model. This study shows a simple way of species distribution modelling that can be applied to, for example, endangered species with limited regional distributions or when studying relatively unexplored species. (Less)
Popular Abstract
Discovering new habitat for an endangered species

When I was a little boy, mother often brought me with on bike rides through our local nature. One day, while out riding through a particular warm and dry area, she’d stopped to show me a sand lizard lying at the side of the road. At that moment she spotted a ladybird in the corner of her eye. Almost having accepted what she saw, she felt the feeling of something being out of place. This surely was one big ladybird. After having another glance she realized it wasn’t a ladybird at all. Turns out, it wasn’t even an insect, but a spider.

On that summer day of 1993 my mother discovered a new species for Sweden, the ladybird spider, Eresus sandaliatus. Having evolved to mimic an ill tasting... (More)
Discovering new habitat for an endangered species

When I was a little boy, mother often brought me with on bike rides through our local nature. One day, while out riding through a particular warm and dry area, she’d stopped to show me a sand lizard lying at the side of the road. At that moment she spotted a ladybird in the corner of her eye. Almost having accepted what she saw, she felt the feeling of something being out of place. This surely was one big ladybird. After having another glance she realized it wasn’t a ladybird at all. Turns out, it wasn’t even an insect, but a spider.

On that summer day of 1993 my mother discovered a new species for Sweden, the ladybird spider, Eresus sandaliatus. Having evolved to mimic an ill tasting ladybird, it’s coloured in red, black and white.

Being biologists, my parents got involved with the conservation of the spider population, which at discovery turned out to be quite small. After several years of conservation, the population has grown in number, but still remains endangered and isolated.

I was curious about what habitat these spiders preferred and I was also wondering if they could be hiding in other parts of Scania. Since ecological knowledge about the species was quite sparse, I combined published knowledge with expert knowledge and created a model, using GIS, which would predict suitable habitat in Scania, the southernmost region of Sweden.

From a number of variables, I choose to work with heat, land use and soil type. The habitat for the ladybird needs to be dry, warm, sandy and having low vegetation (e.g. being grazed by animals).

Since the species only existed in one location in Sweden, I couldn’t test the model statistically. There are however a number of populations on the Danish part of the Jutland peninsula. The model was applied in Denmark and proved to be very effective at identifying the locations of these known locations. Now I could calibrate the model against the Danish localities to make it even better. I applied the results to Scania and several hotspots were identified. Some of these hotspots were visited and evaluated in the field. No hidden populations were discovered, however, several good habitats were identified, which could be very useful if we ever want to increase the distribution range of the ladybird spider within Scania.

The model used was to a large extent based on expert knowledge, but applying it on a calibration dataset gives a way to test the model (and the knowledge) statistically. This method can be applied by other people working with conservation biology, for other endangered species limited to one or only a few localities.

Master’s Degree Project in Biology 30 credits 2017
Department of Biology, Lund University

Advisor: Ola Olsson
Advisors Biodiversity, Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Gerell, Dan
supervisor
organization
course
BIOM01 20171
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8925912
date added to LUP
2017-09-18 15:55:13
date last changed
2017-09-19 08:58:22
@misc{8925912,
  abstract     = {Landscape fragmentation and habitat loss are detrimental to biodiversity, affecting highly specialised species the most. Species distribution models usually require either solid knowledge about the ecological niche of the species or spatial distribution data. Many endangered species have, how- ever, a relatively unexplored ecological niche in combination with a very small area of distribution. A method identifying habitat for such a species was devised and applied on the endangered spider Eresus sandaliatus that is known from only a single locality in Sweden. A prediction model was built using a combination of literature research and expert knowledge about the species’ habitat requirements. The model was tested and calibrated using spatial records of known populations in a neighbouring region. The post-calibration model was applied to Scania and several suitable areas could be identified through a field survey of top predictions made by the model. This study shows a simple way of species distribution modelling that can be applied to, for example, endangered species with limited regional distributions or when studying relatively unexplored species.},
  author       = {Gerell, Dan},
  language     = {eng},
  note         = {Student Paper},
  title        = {Expert-Driven Distribution Modelling: Identifying Habitat for Eresus sandaliatus in Scania},
  year         = {2017},
}