Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA
Explanations for areas of endemism often involve relative climatic stability, or low climate velocity, over time scales ranging from the Pleistocene to the late Cenozoic. Given that many narrowly endemic taxa in forested landscapes display discrete habitat associations, habitat stability should be s...
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| Format: | Article |
| Language: | English |
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International Biogeography Society
2015-07-01
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| Series: | Frontiers of Biogeography |
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| Online Access: | http://escholarship.org/uc/item/3dk4069j |
| _version_ | 1818522811246837760 |
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| author | Daniel G. Gavin |
| author_facet | Daniel G. Gavin |
| author_sort | Daniel G. Gavin |
| collection | DOAJ |
| description | Explanations for areas of endemism often involve relative climatic stability, or low climate velocity, over time scales ranging from the Pleistocene to the late Cenozoic. Given that many narrowly endemic taxa in forested landscapes display discrete habitat associations, habitat stability should be similarly important for endemic persistence. Furthermore, while past climate variability is exceedingly difficult to quantify on millennial time scales, past distributions of habitats may be robustly inferred from paleoecological records. The Olympic Peninsula, Washington, supports a biota with several insular features including 29 endemic plant and animal taxa. Here I present the geographic distribution and habitat of the endemic taxa, and then examine the vegetation stability of the past 14,300 years from five pollen records associated with discrete vegetation zones on the peninsula. I show that 11 endemics have distributions centered on dry alpine scree and rock in the northeastern quadrant of the peninsula, and nine occur in shaded riparian forests in the southwest. Vegetation turnover during the post-glacial period was smallest in these areas. However, another long pollen record from the western peninsula reveals existence of shrub tundra and greatly reduced forest cover, indicating southward displacement of shaded riparian habitats by perhaps as much as 100 km. Although this study supports an association of post-glacial vegetation stability with endemism, records spanning the glacial maximum indicate widespread tundra during long periods of the late Pleistocene and therefore suggest southern displacement of forest-associated endemics. While some of the alpine scree-associated endemics may have persisted <em>in situ</em>, many others likely arrived via a variety of dispersal trajectories. These histories include dispersal from southern refugia towards ocean barriers preventing further northward dispersal, contraction from more widespread distributions, and recent divergence from sister taxa. This study shows that paleoecological records can cast strong doubt on the inference that areas of endemism necessarily imply <em>in situ</em> glacial survival.<br /> |
| first_indexed | 2024-12-11T05:37:49Z |
| format | Article |
| id | doaj.art-2c24a6f188654c9f9362745262ebaff4 |
| institution | Directory Open Access Journal |
| issn | 1948-6596 |
| language | English |
| last_indexed | 2024-12-11T05:37:49Z |
| publishDate | 2015-07-01 |
| publisher | International Biogeography Society |
| record_format | Article |
| series | Frontiers of Biogeography |
| spelling | doaj.art-2c24a6f188654c9f9362745262ebaff42022-12-22T01:19:14ZengInternational Biogeography SocietyFrontiers of Biogeography1948-65962015-07-0172ark:13030/qt3dk4069jVegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USADaniel G. Gavin0University of OregonExplanations for areas of endemism often involve relative climatic stability, or low climate velocity, over time scales ranging from the Pleistocene to the late Cenozoic. Given that many narrowly endemic taxa in forested landscapes display discrete habitat associations, habitat stability should be similarly important for endemic persistence. Furthermore, while past climate variability is exceedingly difficult to quantify on millennial time scales, past distributions of habitats may be robustly inferred from paleoecological records. The Olympic Peninsula, Washington, supports a biota with several insular features including 29 endemic plant and animal taxa. Here I present the geographic distribution and habitat of the endemic taxa, and then examine the vegetation stability of the past 14,300 years from five pollen records associated with discrete vegetation zones on the peninsula. I show that 11 endemics have distributions centered on dry alpine scree and rock in the northeastern quadrant of the peninsula, and nine occur in shaded riparian forests in the southwest. Vegetation turnover during the post-glacial period was smallest in these areas. However, another long pollen record from the western peninsula reveals existence of shrub tundra and greatly reduced forest cover, indicating southward displacement of shaded riparian habitats by perhaps as much as 100 km. Although this study supports an association of post-glacial vegetation stability with endemism, records spanning the glacial maximum indicate widespread tundra during long periods of the late Pleistocene and therefore suggest southern displacement of forest-associated endemics. While some of the alpine scree-associated endemics may have persisted <em>in situ</em>, many others likely arrived via a variety of dispersal trajectories. These histories include dispersal from southern refugia towards ocean barriers preventing further northward dispersal, contraction from more widespread distributions, and recent divergence from sister taxa. This study shows that paleoecological records can cast strong doubt on the inference that areas of endemism necessarily imply <em>in situ</em> glacial survival.<br />http://escholarship.org/uc/item/3dk4069jallochthonous endemismPollen recordsCommunity rate of changeMultidimensional scaling |
| spellingShingle | Daniel G. Gavin Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA Frontiers of Biogeography allochthonous endemism Pollen records Community rate of change Multidimensional scaling |
| title | Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA |
| title_full | Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA |
| title_fullStr | Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA |
| title_full_unstemmed | Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA |
| title_short | Vegetation stability and the habitat associations of the endemic taxa of the Olympic Peninsula, Washington, USA |
| title_sort | vegetation stability and the habitat associations of the endemic taxa of the olympic peninsula washington usa |
| topic | allochthonous endemism Pollen records Community rate of change Multidimensional scaling |
| url | http://escholarship.org/uc/item/3dk4069j |
| work_keys_str_mv | AT danielggavin vegetationstabilityandthehabitatassociationsoftheendemictaxaoftheolympicpeninsulawashingtonusa |