Biogeography of Islands. Oceanic islands Sky islands (mountain tops) Forest fragments Prairie potholes Prairie remnants

Transcription

1 Biogeography of Islands Oceanic islands Sky islands (mountain tops) Forest fragments Prairie potholes Prairie remnants

2 Biogeography of Islands Oceanic islands Sky islands (mountain tops) Forest fragments Prairie potholes Prairie remnants

3 Biogeography of Islands Islands biologically important 1. Dispersal biology Nature of island biota: how it differs from that of the sourcearea, and the nature of adaptations of the successful immigrants that permitted them to reach and colonize the island

4 Biogeography of Islands Islands biologically important 2. Island Biogeography Identifying and quantifying the factors that control 3 phenonmena: rate of island immigration rate of island extinction number of species per island

5 Biogeography of Islands Islands biologically important 3. Adaptive radiations Processes of change by which immigrant species diversify and radiate to occupy ecological niches that on the mainland are normally occupied by other groups

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7 Island patterns: three interrelated ecological and biogeographical observations of patterns on islands have been made 1. Species-area relationships Relationship within archipelagos between the sizes of individual islands and the number of species that comprise their biota.

8 Long been recognized that larger islands have more species Philip Darlington quantified this relationship for the herptofauna of the West Indies 1. Species-area relationships Relationship within archipelagos between the sizes of individual islands and the number of species that comprise their biota.

9 In order to double the number of species, the size of the island had to increase 10 fold 1. Species-area relationships Relationship within archipelagos between the sizes of individual islands and the number of species that comprise their biota.

10 This general relationship (although with different ratios) was later seen with flowering plants and birds in the Pacific.

11 This general relationship (although with different ratios) was later seen with flowering plants and birds in the Pacific.

12 2. Effect of isolation Isolated islands have fewer species than expected based on size alone.

13 3. Species turn-over Islands have more species turnover than continental landmasses.

14 3. Species turn-over Islands have more species turnover than continental landmasses.

15 number of bird species increased rapidly until 1920, and then species number remained relatively constant despite changes in composition of the avifauna some of the later arrivals were successful colonists, replacing about an equal number of species that became extinct 3. Species turn-over Islands have more species turnover than continental landmasses.

16 Robert MacArthur (ecologist, competetion) and E.O. Wilson (ant taxonomist, biogeographer) produced in 1963 (small paper in Evolution) and 1967 (book at right) a unifying theory to explain these three basic characteristics of insular biotas:

17 1. Number of species increases with increasing island size 2. Number of species decreases with increasing distance to the nearest continent or other source of species 3. Continual turnover in species composition due to recurrent colonizations and extinctions, but the number of species remains constant

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20 Applications of Island Biogeographic Theory to Nature Preserves SLOSS Single Large or Several Small Island nature of its habitat today swamp forest in Arkansas where re-discovered in 2004 Ivory-billed woodpeckerconsidered extinct since 1944

21 Applications of Island Biogeographic Theory to Nature Preserves SLOSS Single Large or Several Small Single Large vs. Several Small Circular vs. "Peninsular Clumped vs. Spread out Connected vs. Unconnected

22 Today, we are going to test species-area relationships in the Jordan River nurse logs

23 Today, we are going to test species-area relationships in the Jordan River nurse logs Method 1. Measure area of nurse log islands and record numbers of vascular species 2. We will graph out species-area relationships (including previous years data) you may see these results on the final 3. Group 1: Adam, Annaka, Ben, Beth, Emily 4. Group 2: Erin, Ken, Lynelle, Sam, Stephen