So happy to see my 2n thesis chapter published in Diversity and Distributions 🥳🥳 How does local climate influence ecological communities? Answer: #Thermophilisation caused by #colonisation and local #extinction of mountain butterflies 🦋 #ClimateChange#Refugia Small thread below⬇️
How does the ability of localized refugia to protect species against global warming depend on their climatic conditions? To find out, we looked at changes to butterfly communities in four mountain ranges in central Spain between 1984-2005 and 2017-2022.
📷 Parnassius apollo (Sara Castro-Cobo)
We revisited 74 field sites where we were lucky to have butterfly data from historical surveys. To estimate changes to the climates that butterflies experienced near the ground we used the mechanistic Microclima model. besjournals.onlinelibrary.wiley.com/doi/full/10....
The geographic ranges of species reflect their climatic tolerance or “thermal affinity”. To summarise this for butterfly species in each community we used the average temperature across their Iberian Peninsula distributions – known as the Community Temperature Index or CTI. More info about it ⬇️
We found CTI to be greater in hotter sites in both periods. CTI also increased in many sites over time – known as community thermophilisation. But this could result from colonisations by species favouring hot conditions, or extinctions of species that do not tolerate warming.
We deduced that colonisation and extinction took place at similar rates, as species richness and average variation in thermal affinities per site did not change. If colonisations were more important we expected both values to rise, if extinctions were more important we expected both to decline.
Comparing thermal affinities for colonising versus extinct species across sites confirmed that species favouring warm conditions were colonising, and species preferring cool conditions were experiencing local extinctions. As a result, CTI increased.
We also found that species tolerating a wider range of temperatures across their range (thermal niche breadth) increased the number of sites they occupied, especially if they preferred warm conditions. Species with narrow thermal preferences or cold affinities decreased most.
Has CTI changed equally across the mountain regions and study sites? No, communities occupying sites with cold conditions historically increased their CTI most, especially in Sierra de Gredos and Javalambre. Community changes differed between the four regions.
So, mountain butterfly communities in central Spain became more dominated by species with warm thermal affinities and broader thermal niches. To adapt conservation to climate change, a regional perspective is needed to provide a wide range of local climates and rates of change.
