Data from: Historical biogeography supports Point Conception as the site of turnover between temperate East Pacific ichthyofaunas

The cold temperate and subtropical marine faunas of the Northeastern
Pacific meet within California as part of one of the few eastern boundary
upwelling ecosystems in the world. Traditionally, it is believed that
Point Conception is the precise site of turnover between these two faunas
due to sharp changes in oceanographic conditions. However, evidence from
intraspecific phylogeography and species range terminals do not support
this view, finding stronger biogeographic breaks elsewhere along the
coast. Here I develop a new application of historical biogeographic
approaches to uncover sites of transition between faunas without needing
an a priori hypothesis of where these occur. I used this approach to
determine whether the point of transition between northern and southern
temperate faunas occurs at Point Conception or elsewhere within
California. I also examined expert-vetted latitudinal range data of
California fish species from the 1970s and the 2020s to assess how
biogeography could change with the backdrop of climate change. The site of
turnover was found to occur near Point Conception, in concordance with the
traditional view. I suggest that recent species- and population-level
processes could be expected to give signals of different events from
historical biogeography, possibly explaining the discrepancy across
studies. Species richness of California has increased since the 1970s,
mostly due to species’s ranges expanding northward from Baja California
(Mexico). Range shifts under warming conditions seem to be increasing the
disparity between northern and southern faunas of California, creating a
more divergent biogeography.