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Lacking tropical data

Posted by kfeeley on 07 Feb 2017 at 15:52 GMT

Wiens (2016) claims to have broad taxonomic and geographic coverage of studies in his meta-analysis of species’ range shifts due to climate change. Unfortunately, this is not the case. In fact, from the true tropics (i.e., excluding the studies from the Santa Catalina Mountains of Arizona, USA, the Appalachian Mountains of north Georgia, USA, and the high Himalayas that Wiens categorizes as “tropical” for the purposes of his analyses), only 5 studies representing a total of just 341 species (35% of species, 18% of studies) are included. All but one of these tropical studies (of 55 Andean bird species) are from oceanic islands (Borneo [insects], New Guinea [birds], Madagascar [amphibians], and Hawaii [plants]). All tropical plants are represented by just 4 grasses in Hawaii.

The lack of data from the tropics is not Wiens’ fault but rather reflects a true underlying disparity in the state of knowledge about different systems of the world. Simply put, we know much more about the effects of climate change in North America and Europe than we do the effects of climate change in the tropics. That said, Wiens needs to be more forthright in acknowledging this disparity. Furthermore, given this extreme lack of data, it is clearly premature to conclude that "there were significant effects of climatic region overall, with extinction more common in tropical regions" and that "this pattern of more frequent tropical extinction arose from a much lower frequency of extinctions for temperate plants". Four grasses from Hawaii tell us next to nothing about how the thousands of tropical plants are responding to climate change. Or even if we lump the tropics and subtropics together as does Wiens, 4 grasses from Hawaii, 27 mountain desert plants from Arizona and 124 high-elevation Himalayan plant species (all with ranges restricted to elevations >3500 m asl) provide little information about how the thousands of other tropical and subtropical plants are responding to climate change. The tropical data void is real and it is troublesome (Feeley et al. 2016a,b). But before we can begin to address this lack of data it needs to be acknowledged and recognized for the problem that it is.

Kenneth J. Feeley, PhD
Smathers Chair of Tropical Tree Biology
Department of Biology, The University of Miami
Coral Gables, FL USA 33146

Literature cited:
Wiens JJ (2016) Climate-Related Local Extinctions Are Already Widespread among Plant and Animal Species. PLOS Biology 14(12): e2001104. doi: 10.1371/journal.pbio.2001104

Feeley KJ, Stroud JT, and Perez TM. 2016. Most “global” reviews of species’ responses to climate change aren't truly global. Diversity and Distributions. In Press.

Feeley KJ, Silman M, and Duque A. 2016. Where are the tropical plants? A call for better inclusion of tropical plants in studies investigating and predicting the impacts of climate change. Frontiers of Biogeography. 7(4). fb_27602.

No competing interests declared.

RE: Lacking tropical data

jwiens761 replied to kfeeley on 08 Feb 2017 at 00:31 GMT

Hi Ken:

Thank you for your comment. Can you please explain by what criterion Borneo, New Guinea, and Madagascar are considered "oceanic" islands? I am pretty sure that they are actually considered "continental" islands and not "oceanic" islands. Perhaps you should correct your posting with this in mind?

Also, I did explain that tropical includes subtropical. Perhaps you missed this?

Thank you again for your comment.

all the best,

John J. Wiens

Competing interests declared: Author of paper.

RE: RE: Lacking tropical data

kfeeley replied to jwiens761 on 09 May 2017 at 20:39 GMT

John W. is correct that Borneo, New Guinea, and Madagascar are continental islands (I was really just trying to say that these islands are in the ocean and not in lakes, but I was very sloppy with my terminology - unfortunately I can't find a way to edit or correct the original post). But regardless of how the islands were formed, it does concern me that essentially all of the tropical systems where we have looked for the effects of climate change are on islands. Clearly more work needs to be done on the mainland.

It is stated explicitly in the original paper that subtropical and tropical sites are being lumped together into one "tropical" category. I don't think that this lumping is justified. Ecosystems from northern Arizona and the high himalayas are very different from equatorial or other tropical ecosystems. By lumping such disparate systems into one "tropical" category, we don't gain any real power or additional insight into the working of the tropics. And by lumping these systems together, the bias against the tropics in climate change studies is masked. Unfortunately, I don't think that we yet have enough data from the tropics (from islands or the mainland) to make broad generalizations about how tropical systems or species, and especially tropical plant species, are being affected by climate change.

No competing interests declared.