L17: Practical examples of species distribution models

Question 1

Predicting species’ distributions has become an important component of conservation planning in recent years, and a wide variety of modelling techniques have been developed for this purpose (Guisan and Thuiller, 2005).

Answer 1

1) Identification of areas of endemism
2) Management of ecosystem services
3) Recovering distributional ranges of extinct species

Question 2

Example 1: Chameleons in Madagascar

Answer 2

Presence of a lot of species which only occur in Madagascar
Predicting distributions of known and unknown reptile species in Madagascar (Raxworthy et al, 2003)
Data:
29 modern data sets of environmental land coverage
621 chameleon occurrence localities from Madagascar (historical and recent)

Question 3

Example 2: Management of ecosystem services (pollination)

What are ecosystem services?

Answer 3

The set of ecosystem functions that are useful to humans (Kremen, 2005)

Question 4

Example 2: Management of ecosystem services (pollination)

Questions being asked for SDMs

Answer 4

In potential locations for the cultivation of pollination dependent crops, what is currently the relative level of pollination service provision?

To what extent does the current land cover type in a particular location contribute to the provision of pollination services to crops?

Question 5

Example 2: Management of ecosystem services (pollination)

SDM methods

Answer 5

Build hotspot maps
Show where in the landscape the presence of bees is higher

Combine with other GIS processes to understand where the pollination services are actually being delivered.

Question 6

Example 2: Management of ecosystem services (pollination)

Conclusions

Answer 6

1) In areas with low to intermediate pollination index, land management should be targeted to increase availability of suitable wild bee nesting habitat near and around pollinator-dependent crops to enhance pollination provisioning by wild bees.

2) Our hotspot map suggests that Nordic agricultural areas (e.g. Denmark, Finland, Iceland, Norway, and Sweden), are located outside the climatic range of many wild bee species, and here pollination service delivery may benefit from increasing the number of beehives to ensure high pollinator densities.
3) This model provides an approach that can quickly obtain a first approximation for land managers to identify potential regions to invest in actions to conserve or restore nesting habitats to enhance pollination service delivery.

Question 7

Example 3: Recovering the distribution and migratory patterns of the extinct Carolina parakeet

What is it?

Answer 7

Neotropical parrot: native to the eastern, midwest and plains states of the United States.

Question 8

Example 3: Recovering the distribution and migratory patterns of the extinct Carolina parakeet

Extinction cause?

Answer 8

The final extinction (1904) of the species is somewhat of a mystery, as it happened rapidly.

Humans had at least a contributory role in the extinction of the Carolina parakeet: hunting, deforestation, poultry disease (?), and pet trade.

However, to know what happened you need to map the distributions….

How come a species that looked fine could go extinct so fast?

Question 9

Recovering the distribution and migratory patterns of the extinct Carolina parakeet

Aim?

How?

Answer 9

Aim: informing modern conservation programs focused on threatened (extinction), closely related species.
To understanding extinction as a process: the end, when species actually go extinct.

How? Building a database with historical accounts with museum collections (e.g. Lewis and Clark expedition journal from the 1800s) and using Maxent.

Question 10

Recovering the distribution and migratory patterns of the extinct Carolina parakeet

What was found?

Answer 10

Evidence that the Carolina parakeet’s range was much smaller than previously believed

Populations with smaller range sizes are more vulnerable to extinction (Payne and Finnegan, 2007).

Question 11

Recovering the distribution and migratory patterns of the extinct Carolina parakeet

Comparisons of seasonal distribution models

Answer 11

Western subspecies may have moved between breeding and winter seasons, whereas the eastern subspecies appears to have not.

These results also suggest that the subspecific taxonomy may be valid!

Further genetic testing could be targeted to verify the validity of these subspecies, and to explore whether or not gene flow existed between the two subspecies in areas where they may have overlapped in the southeastern United States.

Question 12

SDMs and Climate change

Modeling the potential impacts of Climate change on species’ distributions

Answer 12

1) Climate change has the potential to significantly impact the distribution of species (Example 4).
2) The general approach is to calibrate the models based on current distributions of species and then predict future distributions of those species across landscapes for which the environmental input variables have been perturbed to reflect expected changes (Example 4 and 6).
3) Past distributions to e.g. understand how drivers of change influence in the past (Example 5).

Question 13

Example 4: Climate warming and the decline of amphibians and reptiles in Europe

Aim

Answer 13

Aim: Explore the relationship between current European distributions of amphibian and reptile species and observed climate, and project species potential distributions into the future.

Question 14

Example 4: Climate warming and the decline of amphibians and reptiles in Europe

Which is the impact of increasing temperatures on amphibian and reptile species in Europe?

Answer 14

• Several factors contribute to the vulnerability of amphibians to the projected effects of climate change.
• 1/3 of amphibian species are already at risk of extinction.
• habitat loss, disease, invasive species, overexploitation, and chemical pollution

Question 15

Example 4: Climate warming and the decline of amphibians and reptiles in Europe

More sensitive to climate cooling than warming?

Answer 15

Amphibian: Ectothermic ‘cold- blooded’: rely on external warmth to raise their body temperature and become active.
Their ability to cope with lower temperatures is limited (most species are unable to live at temperatures below -4 Co).

Question 16

Example 4: Climate warming and the decline of amphibians and reptiles in Europe

Some conclusions

Answer 16

1) Unlimited dispersal: species expand! This is because warming in the cooler northern ranges of species creates new opportunities for colonization.
2) If species are unable to disperse, then most species are projected to lose range.
3) Loss of suitable climate space for species is projected to occur mainly in the south-west of Europe, including the Iberian Peninsula, whilst species in the south-east are projected to gain suitable climate. This is because dry conditions in the south-west are projected to increase.

Question 17

Example 5: Testing the accuracy of SDMs for economically valuable species in Europe

How?

Answer 17

1) Devised a methodology to hindcast SDMs for 7 economically valuable European tree species
2) Three climatically distinct periods considered:
• Medieval Warm Period (900-1300)
• Little Ice Age (1600-1850)
•20th century warming
3) Modelled distribution compared against actual distribution as displayed in European fossil pollen database.

Question 18

Example 5: Testing the accuracy of SDMs for economically valuable species in Europe

Some conclusions

Answer 18

High model performance statistics in all classes
A tendency to a decrease in performance (but still high) in more human managed species distributions (e.g Vitis vinifera, Olea europaea)
Future predicted modelling of these species in Europe using SDMs is robust
Results also demonstrates individual characteristics of species e.g. rates of response to climate warming

Question 19

Example 6: Iberian Lynx and climate change

Background

Answer 19

Climate change threatens the Iberian Lynx(Lynx pardinus) despite conservation efforts
Over €90 million has been spent since 1994 to mitigate the extinction risk of this charismatic animal, mainly through habitat management, reduction of human- caused mortality and, more recently, translocation. But Araújo and his colleagues aren’t convinced that those programs could work.

Question 20

Example 6: Iberian Lynx and climate change

Simulate demographic responses of lynx to spatial patterns…

Answer 20

of rabbit abundance (rabbit, 80% of Iberian lynx consumption) conditioned by disease, climate change, and land use.
Model trophic interactions of species, such as predators and their prey!

Combined effects of climate change, prey availability (rabbit, 80% of Iberian lynx consumption) and management intervention on the persistence of the Iberian lynx. Also rabbit declined in the 20th century due to two diseases.

Question 21

Example 6: Iberian Lynx and climate change

Climate change is predicted to…

Answer 21

have a rapid and severe negative influence on lynx abundance.
Even with global cuts to anthropogenic greenhouse gas emissions.
By shifting reintroduction programs further north, Lynx could not only survive climate change, but rebound, the researchers found.
Peninsula-wide strategy considers habitats in the northern half of Iberia as potential refugia from climate- induced shifts in physiological conditions, rabbit abundance and habitat availability.
Habitat in the south, where the two extant populations of lynx persist, is most likely to be inhospitable to lynx by the middle of this century

Question 22

Example 7: SDMs and invasive species

Process involved

Answer 22

Identifying the problem
Defining the objectives
Defining possible actions 
Consequences of actions 
Trade offs between costs and benefits of actions 
Decision