29. Rabinowitz, D. 1981. Seven forms of rarity. Pages 205-217 in H. Synge, ed.,
The Biological Aspects of Rare Plant Conservation. John Wiley and Sons, New
York.
Blog Author: Ben Clinch
Blurb Author: Kevin J. Gaston
-Professor of Biodiversity & Conservation, University of Exeter
-Co-chair of Cornwall & Isles of Scilly Local Nature Partnership, Founding Director of Environment & Sustainability Institute (University of Exeter)
-International Ecology Institue Prize in terrestrial ecology
-Member of Academia Europaea
-Research interests in common ecology, nighttime ecology, and personalized ecology
Paper Author: Deborah Rabinowitz
-Ph.D. in theoretical population biology, University of Chicago
-Research interest in mangrove ecology and zonation
-First female faculty member in the Ecology & Evolutionary Biology Department, University of Michigan
-Committee member on the National Science Foundation, the National Academy of Sciences and the Ecological Society of America
Summary/Main Points:
Main Question: How can species rarity be characterized? How does natural selection operate on rare species? What constitutes rarity?
-Background: The definition of rarity has been confusing among scholars. Multiple factors may play into the rarity of a species, which can cause evolutionary and ecological consequences. Previous generalities of rare species, such as being competitively inferior or that interbreeding is restricted, have distorted views on them.
-Assumptions: There are three aspects to the situation of a species: geographic range, habitat specificity, and local population size.
Methods:
-Use three categories of rarity to create a 2x2x2 cell chart to compare and contrast different species types using previous literature
-Categories: 1) Range- large vs small 2) Specificity- wide vs narrow 3) Local pop size- large, dominant vs small, non-dominant
Results:
-Two cells don’t have many specimens (small range & wide habitat specificity)
-Species with wide ranges and narrow habitat specificity are easy to come by, but can become easily endangered due to habitat destruction
-Rare species are contradictory in competition, research finding them uniformly superior
Conclusions:
-Sparse species grow best when sparse, common species grow best when common
-Rarity cannot be an adaptive strategy, natural selection instead acts on traits which offset rarity disadvantages to prevent extinction
-“Rare” species need comparative data of a common related taxa (control) to determine whether rare traits are unique to the species or are just random traits in general
Comments/Questions:
-Before reading this I thought rarity just meant harder to find, no real idea of the term. This paper gave some interesting insights to form a more accurate definition.
-This paper is fairly old, what are current thoughts in this realm? Has subsequent research led to additional rarity categories?
I like how the author presented clear examples for each of the categories of rarity she described. I found particularly interesting the experiment she did, showing how the alleged competition was not the cause for the rare grasses she studied. I think many people hypothesize competition is a main driver for many processes, but only a few set to prove it.
ReplyDeleteI like that the author pointed out that rare species are not necessarily poor competitors. One could look at it differently and assume rare species are good competitors, because they are capable of persisting in small numbers. As always, there are many potential reasons a species is rare, and jumping to a conclusion about its competitive ability seems illogical.
ReplyDeleteI think the classification proposed in this paper is a creative way of including different aspects on rarity and had an important impact in the understanding that rarity can come from different causes. Nonetheless, a problem I see in this scheme is that it requires the species to be classified as abundant/non abundant or wide/ narrow habitat specialization, which as we discussed in previous classes, can bring some subjectivity (specially regarding with niche dimension width are we measuring).
ReplyDeleteI appreciate the rigor and approach the author went through to categorize 'rarity'. It is a term that is thrown around a lot and I would have liked to be able to say I've seen this classification scheme before reading the primary paper. However, it did not seem to catch on, as the blurb mentioned. Additionally, I'd like to see this classification scheme applied to mammals or reptiles in addition to the plant examples given.
ReplyDeleteI agree with Ben about his idea of rarity. I just assumed that meant something didn't have much of it anymore and it was hard to find or something like that. I'm super shocked to find out there are three classifications of it. I loved how the writer explained in depth the classifications and even gave examples of the classifications. Also I'm sure we'll go over it in class... but can we go over figure 3?
ReplyDeleteI've always automatically associated rare species to endangered species, in the context of species that are reduced in population because of human impact, so it's interesting to see different interpretations of rarity in this paper. I like the paragraph near the end about natural selection and sparse species. I thought if a species is selected for, then it would increase in number. So it is surprising to know that rarity is an advantage.
ReplyDeleteThis is a good way of looking at the rarity in terms of understanding the different type of rareness in different conditions and habitats. It is very important to correctly distinguish and assess the true cause and effects of rare species for conservation management purposes. The author stated the differences clearly and systematically with the reasonable explanations. It is interesting to look at some organism are adapted to be rare.
ReplyDeleteI liked this paper. It was very easy to read with it’s almost casual narrative-like language (mangroves are objectionable because they come between the people and the sea and “if I were a horse”). Itsbis also very clear and organized as it walks through the chart and gives specific examples for each.
ReplyDeleteI also appreciated that she imposed limits on the model- clarifying that it was just an “aid in focusing our thoughts.” As much as I would love to be able to quantify everything imagineable, I think a lot of models like this are taken too literally.
I think that this could be applied on an even more specific level. These species could then be categorized by other risks like invasive competition and human exploitation.
ReplyDelete