A changing climate has hurt butterfly species in the Sierra Nevada, reducing species richness by about fifty percent in the last 35 years. so reports a team at UCDAvis led by Arthur Shapiro, and reported in the PNAS: Compounded effects of climate change and habitat alteration shift patterns of butterfly diversity — PNAS
Here we present 35 years of data on 159 species of
butterflies from 10 sites along an elevational gradient spanning 0–
2,775 m in a biodiversity hotspot, the Sierra Nevada Mountains of Northern California. Species richness has declined at half of the sites, with the most severe reductions at the lowest elevations, where habitat destruction is greatest. At higher elevations, we observed clear upward shifts in the elevational ranges of species, consistent with the influence of global warming.
Or, in the blunter tones of a story from that wild-eyed lefty journal USA Today:
The unprecedented, 35-year analysis of butterfly populations in the Sierra Nevada details how several species are fleeing to higher elevations to escape warming temperatures.
Those butterflies that already live on mountaintops and can't adjust to the heat have "nowhere else to go but heaven," says Arthur Shapiro, a biologist at University of California-Davis who collected the data.
Climate is clearly one factor degrading populations and pushing species up the mountains, but another agent at work is habitat destruction:
This suggests that some factor in
addition to climatic change has affected butterfly species richness
…We suggest habitat alteration at low elevations,
which has likely destroyed habitat directly (potentially
affecting both larval hosts and adult nectar resources) and
reduced connectivity among habitats.
Next question: How to save these and related species? The authors suggest preservation not just of habitat and species, but of "fauna." Hmmmm....
