Predicting range shifts

Question 1

Bioclimatic envelope model principles

Answer 1

•Principle to record the relationship between species current distribution and current climate
•Then predict future distributions in different climates
•E.g. salamanders in N America - 3 different spp (N, mid and S)
-range loss predicted for S spp 85-100% - conservation can focus here
•CC has escalated so much, some predictions are now out of date

Question 2

General findings of models for 100s of spp

Answer 2

•NE shift in range boundary massive - 100s km
•Species lost 20% of range on average
•31 predicted to lose >90%
•Little overlap between old and new around 38-53%
•Endemic overlap mean 14-34%
-10 spp had no overlap, need to be able to disperse

Question 3

Problems with the model

Answer 3

1. Not based on global ranges (only Eu)
2. Spatial scale based on average conditions in large grid cells where can find lots of variation in this (like 1.5°C) difference in N and S slopes
3. Ignores local adaptations - assumes all will respond the same to CC
4. Assumes climate regulates range limits - when other factors do it too
5. Human factors can be more important than climate

Question 4

Not based on global ranges…

Answer 4

•Thekla lark - used in Eu listing, and predicted to lose 75% of existing range - new being 65% of old one
-but spp occurs in N and E Africa so can cope with warmer and drier climates

Question 5

Ignores local adaptations…

Answer 5

E.g. looking at plant Silene ciliata in 2 settings, 1 low height and 1 high height (snow melts 7 days later and is 2°C cooler higher up)
-swapped their seeds to opposite sites
-showed through % survival local individuals had home advantage
Evidence of local adaptation

Question 6

Assumes climate regulates range limits

Answer 6

Other factors regulating range limits…
•Dispersal- distribution limited by not travelling through unsuitable habitat to new
•Competitive interactions

Question 7

Human factors more important?

Answer 7

Red-backed shrike - envelope predicted a massive expansion in range, but its range massively reduced
-this was due to farming etc. couldn’t adapt (habitat specialist)
Kilimanjaro upper tree line shifted down 800m - predict it would go up…
-partly due to deforestation but mainly water use causing drought higher up

Question 8

Should bioclimatic envelope model be used?

Answer 8

Can predict pop movements - like UK birds, more warm adapted Mediterranean birds moving in - and cold-adapted out of UK
Worked for introduction of 2 butterfly spp based on predictions - pop now increasing

Question 9

Conservation implications of model

Answer 9

Many spp don’t have much overlap
Lots aren’t tracking climatic shifts
Should we facilitate dispersal..
Make space for nature by:
•enhance connections between or join sites (stepping stones etc.)
•create new sites = success of RSPB Ham Wall from peat industry

Question 10

Assisted colonisation

Answer 10

Moving native species out of their ranges and habitats
•controversial - impacts of alien spp etc.
Do when…
•extinction due CC is high risk
•Translocation and establishment are feasible
•The benefits outweigh biological and socioeconomic costs
Mammal introductions within continents have little spp impacts and low impact ranking