Josef UyedaAlways struck by how much more the House Sparrow body size maps match the weather on the worst days of winter than it does the average climate of a region. 1) Today's temperature map 2) House sparrow body sizes 3) USDA planting zones
Just to make clear the implication: Natural selection on days like today is probably responsible for a massive proportion of the geographic variation in body size in House Sparrows vs. all the other factors that influence fitness throughout the year (inc. temp). If you live in the purple area, pour one out for the petite Passers that are dying outside (but don't feel that bad, they're invasive).
Grant Canterbury@pseudacris for sure, and interesting how this cline developed within a century or so from common ancestral population. I think I remember a metabolic rate study on maybe the farthest northern population in Churchill? Would be interesting to look at summit BMR, body size, and winter survivorship of House Sparrows along the cline.
Stephen Cerruti@pseudacris oh good, for a second there I was afraid you were saying the size of house sparrows was causing colder temperatures and started researching how to use AI to eradicate sparrows in a certain size range but exclude juveniles.
Peter Ralph@pseudacris Nice! How much difference is there between the smallest and biggest?
@petrelharp Not really sure, but my best guess from interpreting PC scores and limited raw data is about a 15% change in average mass, maybe 5% in linear measurements? I'm sure someone knows better than me.