Download Island Biogeography - Introduction to Conservation Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! Island Biogeography • Explore the relationships of I and E rates and S to island area and distance • Observe the accumulation of sp on an island, and the approach of I and E rates and S values to equilibrium • Find equilibrium values of I and E and sp • Understand species-area curves and the underlying mathematical relationships • Explore interaction effects of A & D Docsity.com Island Biogeography • Larger islands and closer islands support a greater number of species than smaller or more distant islands • These relationships can be described as ‘species-area’ or ‘species-distance’ • These patterns not only hold for true oceanic islands, but also mountain tops, lakes, and other habitat ‘islands’ Docsity.com Island Biogeography • In the simplest version of the model, all sp have equal probability of I & E • Realistically, I should be inversely related to D • I=imm rate, P=mainland sp pool, S=island richness, D=distance, c=colonization probability, f=scaling factor for distance (which have been estimated c=0.1, f=0.01) I = c (P-S) / f D Docsity.com Island Biogeography • Consider E • E=extinction rate, S=sp richness on island, A=area, q=extinction probability, m=power factor scaling for area • Values for q and m must be derived from the data ((q=0.20, m=0.25) E = qS / Am Docsity.com Island Biogeography • Consider Eq. 1, you can see species accumulate on an island, I will decrease • Conversely, as S increases, E increases • At some intermediate value, I and E will become equal and the S will be in equilibrium I = c (P-S) / f D E = qS / Am Docsity.com Graphical model of one variation of MacArthur-Wilson Dynamic Theory of Island Biogeography Turnover Rate Docsity.com Island Biogeography • This model has been widely adopted for conservation purposes, but do you see any potential flaws? Docsity.com Island Biogeography • The rate at which species are accumulated by increasing area is the slope • All else being equal, more sp on a given area of mainland supports more than same area of island Docsity.com Final pattern: Isolation effect, shown by fewer species on isolated islands, in species-area curve for birds of warm ocean regions: red triangles represent isolated islands (>300 km from next largest land mass) (from Paul Slud) Cocos Island, Costa Rica Docsity.com Both isolation (distance) effects on immigration, and island size (area) effects on extinction, combined into one model--showing different predicted equilibrium species richness values Docsity.com
