{"id":357,"date":"2011-05-31T22:45:56","date_gmt":"2011-05-31T20:45:56","guid":{"rendered":"http:\/\/occamstypewriter.org\/boboh\/2011\/05\/31\/species-area_relationships_dont_overestimate_extinction_rates_from_habitat_loss\/"},"modified":"2011-05-31T22:45:56","modified_gmt":"2011-05-31T20:45:56","slug":"species-area_relationships_dont_overestimate_extinction_rates_from_habitat_loss","status":"publish","type":"post","link":"https:\/\/occamstypewriter.org\/boboh\/2011\/05\/31\/species-area_relationships_dont_overestimate_extinction_rates_from_habitat_loss\/","title":{"rendered":"Species-area relationships don’t overestimate extinction rates from habitat loss"},"content":{"rendered":"

\"This<\/a><\/span>Today at work we had a journal club about a recent paper in Nature<\/i> that had caused a bit of a stir. It had suggested that the reason we don’t see as many extinctions due to habitat loss as we’d expect from empirical relationships (which I will explain in a moment) is because we’re using the wrong ones.
\nUnfortunately0<\/a><\/sup> I had to prepare a seminar for today, so I didn’t have enough time to read the paper properly, and only got as far as working out that I didn’t understand what the authors were doing. And when, in the journal club, the maths was mentioned they all turned to me for help. Eeek – I wanted someone else to explain it all to me! So after the journal club I decided to really think about the paper, and thanks to our new white board I worked out that it was wrong:
\n\"Whiteboard.JPG\"<\/a>
\nAnd, thanks to RMV<\/a> not coordinating their trams and trains during the afternoon commute, I worked out why it was wrong. Now read on…<\/p>\n


\nOK, now we’re below the jump, what’s the problem?
\nIn ecology it’s well know that the number of species you can find in a region is related to the size of the region. This is usually called the Species-Area Relationship, and might look like this:
\n\"SAR.png\"<\/a>
\nThese predict the number of species we’ll find in an area: if we lose area (for example if Paradise gets paved over), they should predict how many species will go extinct from that area. This is useful for conservation, because we can predict how many species we lose if we remove some land (or sea I suppose, if we’re marine biologists). But, when ecologists have looked at areas where land1<\/a><\/sup> has been removed, they see more species than the SAR would predict.
\nThe usual explanation for this is something called the Extinction Debt. This is simply the idea that species hang around for some time before they have all finally shuffled of this mortal coil. So, if we remove half of Wales, it’ll take a bit of time for the species that don’t have enough land to survive in to go extinct: they hang around for a few years declining in number but still managing to hold an Eisteddfod until there’s nobody left.
\nThis new paper that we journal clubbed to day is by He and Hubbell (this is Hubbell of the Unified Neutral Theory of Biogeography fame, and nothing to do with telescopes). They argue that the SAR isn’t a good model for how extinctions will happen, and instead we should use another curve, the Endemics-Area Relationship (EAR). They do this by pointing out that we can calculate extinctions in two ways:<\/p>\n