Species Distribution & Change

Activities to try

1. 1

   Warming the living map: watch suitable habitat move

   Why it works: Distribution change is a band of suitability on the move; populations persist only where conditions let them breed. A full range shift means a trailing edge is lost as a leading edge is gained (though early on, or where the warm limit lies elsewhere, a range may simply expand for a time), and a species with nowhere suitable to follow to (summit, coast, fragmented habitat with no corridor) dies out at that site — a local extinction if it survives elsewhere, but a total loss for an endemic with no refuge anywhere.

   1. Work with a map where a coloured band of 'suitable climate' can be shifted north and upslope as temperature rises (e.g. a slider, successive overlays, or a sequence of printed map frames for 1970, today, and a warmer future).
   2. Predict for each of several species where its range will go as the band moves: a generalist butterfly, a heather-moor or alpine specialist pinned near a summit, and a coastal species pinned against the sea.
   3. Advance the warming and observe what happens to each range: the generalist's range glides north and persists; the mountaintop specialist creeps upslope until the mountain ends and its range contracts to a point and disappears from that site — a local extinction if the species still persists on other mountains or further north, but a total loss if it is a montane endemic with no cooler refuge anywhere; the coastal species is trapped with no room to shift.
   4. State in writing, for each species, WHY it coped, shifted, or was lost, naming the trait (generalist vs specialist, good vs poor disperser, 'nowhere to go').
   5. Repeat for the trailing (southern) edge: explain what happens to the population in the far south as it keeps warming and that area becomes too hot.
2. 2

   Introduce an invader: the same change opens a door

   Why it works: Invasive harm comes from effects such as outcompeting, preying on or spreading disease to residents that are often co-evolutionarily naive; human transport delivers the species, environmental change in the new area (warming, disturbance) can enable establishment, and escape from the enemies of its native range is an additional, distinct factor that can help it thrive. Change produces winners and losers, not a uniform good or bad outcome.

   1. On the same map (or a before/after food-web diagram), introduce a non-native species into disturbed or newly warmed ground and observe its range expanding while residents' ranges shrink.
   2. Write what 'invasive' means precisely — not merely 'non-native', but a non-native species that spreads and harms residents, for example by outcompeting them, preying on them, or spreading disease to them, often because they lack co-evolved defences.
   3. Explain how the invasion is enabled: human transport delivering the species (a way in, not a habitat change), plus environmental change in the NEW area such as warming making new ground suitable or disturbance opening space — and, as a separate factor, add that the invader may also thrive because it has escaped the competitors, predators or diseases that held it in check in its native range.
   4. Connect back to the range-shift activity: articulate how the same change that evicts one species opens the door for another.
3. 3

   Argue from evidence: justify each species' fate

   Why it works: Claims about distribution change must be backed by mechanism and empirical data; differential vulnerability (specialist vs generalist, disperser vs sessile, cold/high-altitude endemic with no escape) predicts which species cope and which are squeezed out.

   1. Work from real, documented case cards (e.g. comma butterfly and Cetti's warbler moving north; ptarmigan and other montane species running out of upslope room; signal crayfish or grey squirrel as invaders), each paired with range maps or data for an earlier decade versus today.
   2. For a chosen species, state a claim about what has happened to its distribution and support it with BOTH the data shown and the mechanism and traits, not a label alone.
   3. Answer challenge questions such as: why did the ptarmigan disappear here but the comma thrive? Why is a specialist more vulnerable to climate change than a near-ubiquitous generalist?
   4. Optionally run this as a role-play debrief: one learner acts as a field ecologist posing the challenge questions and offering case data while others justify each species' fate.
   5. Attempt the diagnostic prompt: 'As the climate warms, a butterfly that used to live only in the south is now found much further north. Explain what has made the butterfly's range move north.'