In the Light of Evolution Volume II: Biodiversity and Extinction (2008) / Chapter Skim
Currently Skimming:
15 Three Ambitious (and Rather Unorthodox) Assignments for the Field of Biodiversity Genetics--JOHN C. AVISE
15 Three Ambitious (and Rather Unorthodox) Assignments for the Field of Biodiversity Genetics--JOHN C. AVISE
Pages 281-296
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 281... ...
An opportunity centers on the concept of Pleistocene Parks that could protect ‘‘legacy biotas'' in much the same way that traditional national parks preserve special geological features and historical landmarks honor legacy events in human affairs. Third, genetic perspectives have become an integral part of many focused conservation efforts by unveiling ecological, behavioral, or evolutionary phenomena relevant to Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697.
|
From page 282... ...
This is ironic because, fundamentally, evolution is genetic alteration through time, biodiversity is genetic diversity (including epigenetic and emergent phenomena) , and nature's genetic diversity is what is being depleted in the current extinction crisis that has spurred the conservation movement.
|
From page 283... ...
Here, I discuss three other areas of opportunity for molecular genetics in evolutionary biology, specifically in the realms of phylogenetics and conservation. For each of these three topics in a discipline that I call ‘‘biodiversity genetics,'' I first summarize conventional wisdom, but then I intend to be provocative by raising scientific proposals that currently are far from mainstream but nevertheless have the potential to invigorate and perhaps even reshape the biodiversity sciences.
|
From page 284... ...
But the two hypotheses do have several distinct predictions. In terms of genealogical expectations, for example, the Tree of Life model predicts that gene trees should be topologically concordant with one another and with the species tree they compose [barring potential complications such as insufficient resolution, hemiplasy (idiosyncratic lineage sorting across successive nodes in a species phylogeny)
|
From page 285... ...
because different DNA sequences may genuinely have highly distinct organismal histories. In evaluating the evidence, biologists must keep an initial open mind with regard to the network model because, under the competing tree model, a subtle danger exists of circular logic: Any comparative dataset can be used to reconstruct a phylogenetic tree when a tree provides the suppositional metaphor for the data analysis.
|
From page 286... ...
the species in named taxa are typically united by some unspecified mix of similarity by resemblance and similarity by descent, and (ii) even when the nested taxonomic ranks in a Linnaean hierarchy do register bona-fide nested clades the rankings remain noncomparable across different kinds of organisms (because no serious attempt has ever been made to normalize assayed characters, equilibrate taxonomic assignments, or even adopt any standardized criteria for taxonomic ranking)
|
From page 287... ...
one-to-one correspondence possible between 17 standard taxonomic ranks in some modern versions of the Linnaean hierarchy [see Mayr and Ashlock (1991)
|
From page 288... ...
It would both foster and facilitate comparisons of evolutionary rates in numerous genetic and phenotypic attributes (because absolute time is the denominator in any rate equation, and the time-clipped taxon names would specify approximate dates of clade origin)
|
From page 289... ...
Many countries, including the United States, have long-established systems of National Parks that usually feature special landscapes and geological formations (such as the picturesque rocky shores of Acadia Park in Maine, the majestic mountains of Glacier Park in Montana, or the special volcanic features of Yellowstone Park in Wyoming)
|
From page 290... ...
aims to partner responsible and forward-thinking members of the hotel/tourism industry with world-class scientists in a global vision to promote science and protect biodiversity as an integral part of the business plan (which would include the acquisition and preservation of extensive nature reserves in key locations, as well as the generation of new funding mechanisms for the biodiversity sciences)
|
From page 291... ...
. An emerging phylogeographic generality is that many, if not most, extant taxonomic species are spatially subdivided into small numbers of highly distinctive historical units (Avise and Walker, 1999)
|
From page 292... ...
. A comprehensive phylogeographic inventory of Earth's microevolutionary history will complement ongoing attempts to identify and catalog all extant species [see Blackmore (2002)
|
From page 293... ...
routinely include genetic appraisals of the following: plant and animal mating systems, behaviors, and natural histories; magnitudes and patterns of population structure due to past and present demographic factors; gene flow, genetic drift, and various categories of natural selection; other evolutionary phenomena such as patterns and processes of speciation, hybridization, introgression, and phylogenetics; forensic analyses of wildlife and wildlife products; and many additional genetic topics that are often highly germane to the principles and the practice of conservation biology. All of these sentiments are standard wisdom among modern biologists.
|
From page 294... ...
An adequate discussion of this topic is far beyond the scope of this chapter, so what follow are merely a few examples of the many types of questions that scientists have answered using molecular markers, but that for one logistical reason or another had been inadequately addressed by earlier field observations or phenotypic assessments. For fuller answers to the following questions and many others like them, all in layperson language, see Avise (2002, 2006)
|
From page 295... ...
seem willing and eager to embrace nature if simply given the opportunity. Therein lies a third grand mission for molecular genetics and the other biodiversity sciences in conservation efforts: to cultivate in students of all ages a sense of awe, respect, and appreciation for the numerous other creatures -- including the charismatically challenged -- that share our crowded and imperiled planet.
|
From page 296... ...
Such efforts should be encouraged, applauded, and rewarded because only an educated public is motivated to demand a place for nature on this human-dominated planet. CONCLUSION The next few decades offer our best and last remaining chance to shepherd appreciable biodiversity through the current global extinction crisis.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.