Complex patterns of expression of heat-shock protein 70 across the southern biogeographical ranges of the intertidal mussel Mytilus californianus and snail Nucella ostrina

摘要: Aim  It is often assumed that species reach their highest densities in the centre of ranges and decline abundance toward edges range. Implicit this notion, which we call abundant hypothesis, assumption range are more stressful to organisms likely show responses climate change. However, an earlier review empirical study patterns across intertidal invertebrates little support for hypothesis further demonstrated few studies have examined either or stress ranges. In part gap due logistical difficulties sampling large geographical Here use invertebrates, relatively simple linear latitudinal ranges, heat-shock proteins, been shown be integrative measure organismal stress, test stressed at We complementary data on population density relationship between proteins overall species’ range. Location  Our programme covered southern half two Pacific Coast North America. Sites were spread northern Baja California, Mexico Vancouver Island, Canada, a c. 22 degrees latitude. Method  sampled levels protein 70 (Hsp70) eight 12 individuals from each 20 sites mussel Mytilus californianus 11 snail Nucella ostrina, throughout The relationships Hsp70 site (1) latitude site, (2) site's position (3) average determined. Results  No significant was found latitude, density. Complex did emerge may explained by nonlinear gradients environmental conditions along coast. Specifically, observed peak values both Oregon, where zones disproportionately exposed daytime emersion (exposure air) summer months collections. A second M. south Point Conception, marked dramatic shifts warmer sea temperatures decreased wave exposure. Main conclusions  Patterns emerged not predicted models based hypothesis. they consistent with complex pictures heat condition gradient recent studies. suggest complexity, species-specific differences local effects must considered before generalizing abundance, limits