tag:blogger.com,1999:blog-3164804243040726299.post8945063560909892999..comments2024-03-19T06:40:22.220-04:00Comments on The EEB & Flow: Have humans altered community interactions?Marc Cadottehttp://www.blogger.com/profile/08335319636148357534noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-3164804243040726299.post-85964651447298693352016-02-01T11:23:02.030-05:002016-02-01T11:23:02.030-05:00Thanks Jessica - I will definitely read the pollen...Thanks Jessica - I will definitely read the pollen paper! I appreciate the discussion you and Brian have contributed here - lots to think about.Caroline Tuckerhttps://www.blogger.com/profile/09319215430054509345noreply@blogger.comtag:blogger.com,1999:blog-3164804243040726299.post-85535231167110226522016-01-31T20:39:10.350-05:002016-01-31T20:39:10.350-05:00I'll note that the pollen data are the subject...I'll note that the pollen data are the subject of a separate paper entirely! We didn't address the issue of timing of the shift from mostly aggregated to mostly segregated pairs in that paper, but rather tried to attribute particular significant species pairs to being caused by differences in environmental niches, potentially dispersal limitation, or, if none of those seemed to be a factor, a potential species/taxa interaction. I tend to take the extreme shifts in % aggregation prior to 15 kyr BP with a grain of salt because there are fewer sites during those times...so focusing on data from 14 kyr BP to the present you can see the slow but steady shift from dominance by aggregated pairs to dominance by segregated pairs.<br /><br />Here's the link to that paper on Wiley, though if anyone needs a reprint they can email me at jblois ucmerced edu: http://onlinelibrary.wiley.com/doi/10.1111/ecog.00779/abstractJessicahttps://www.blogger.com/profile/12179456460305908661noreply@blogger.comtag:blogger.com,1999:blog-3164804243040726299.post-8770411518839780622016-01-23T12:40:34.007-05:002016-01-23T12:40:34.007-05:00Hi Jon - thanks for your thoughts. I wondered abou...Hi Jon - thanks for your thoughts. I wondered about the pollen data as possibly a more consistent source of data (although I didn't know whether biased preservation or difference in dispersal of different species were issues). It would have been great if they had provided a separate plot for the pollen data.<br /><br />I think the Extended Data Figure 3 still makes me uncertain how strong the relationships the authors found were, since once the modern data are removed from the loess regression, the resulting plot shows a variable trend rather than a decreasing one. But again, perhaps the relationship for pollen only would be convincing - I just can't tell looking at the plot...Caroline Tuckerhttps://www.blogger.com/profile/09319215430054509345noreply@blogger.comtag:blogger.com,1999:blog-3164804243040726299.post-55195606512641476252016-01-22T10:43:38.052-05:002016-01-22T10:43:38.052-05:00Looking at their Figure 2, it strikes me that if t...Looking at their Figure 2, it strikes me that if the pollen data are removed, then there is (at least visually) a negative relationship between the temporal extent/grain and proportion aggregated. The pollen data definitely drive the shape of the line from 10Ka to the Recent. I wish they'd just plotted the pollen data separately on a linear axis, since it's sampled so evenly through time...Jonhttps://www.blogger.com/profile/13728872012920505418noreply@blogger.comtag:blogger.com,1999:blog-3164804243040726299.post-33593903540367705412016-01-22T10:38:14.360-05:002016-01-22T10:38:14.360-05:00Looking at their Extended Data Table, the issue of...Looking at their Extended Data Table, the issue of scale seems to be completely mitigated in the pollen-based subset of their data. The spatial and temporal scales are identical for the 4200+ pollen localities spanning 21,000 years (these are almost certainly core data, hence the detailed data on spatio-temporal resolution). Pollen is essentially indestructable, so it's basically a gold-standard since the issues of biased preservation don't really apply to it.<br /><br />I agree that co-occurrence data is far from optimal, but the marked departure in co-occurrence patterns from the identically-scaled pollen data is definitely interesting. The fact that the same general shift is observed in the other datasets (which do have all of the problems you described) still seems impressive.<br /><br />There is a lot more spread in the aggregation/segregation in the oldest pollen data, but those are also based on *way* smaller data sets (<100 sites per 1kyrs before 13Ka vs >200 sites per 1kyrs for 12Ka and younger).Jonhttps://www.blogger.com/profile/13728872012920505418noreply@blogger.com