Category: Wild relatives

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Fido decoded

An article by Elaine Ostrander in the latest American Scientist summarizes recent advances in canine genomics, which have been considerable:

The dog genome has been mapped and sequenced. A host of disease loci have been mapped, and in many cases the underlying mutations identified. Our understanding of how dog breeds relate to one another is beginning to develop, and we have a fundamental understanding of the organization of the canine genome. The issue of complex traits is no longer off-limits. We have begun to understand the genetic portfolio that leads to variation in body size and shape, and even some performance-associated behaviors.

Some snippets:

  1. Between-breed genetic variation is about 27.5% of the total, compared to about 5% between human populations.
  2. Dog breeds fall into 4 main groups: Asian and African dogs, plus grey wolves; mastiffs; herding dogs and sight hounds; and modern huntings dogs.
  3. 75% of the 19,000 genes that have been identified in the dog genome show close similarities with their human counterparts.
  4. Variation in a single gene (IGF1) explains a lot of the size differences among and within breeds.

What to do with all this information?

It is certainly hoped that the disease-gene mapping will lead to the production of genetic tests and more thoughtful breeding programs associated with healthier, more long-lived dogs. It will be easier to select for particular physical traits such as body size or coat color… Finally, canine geneticists will have a chance to develop an understanding of the genes that cause breed-specific behaviors (why do pointers point and herders herd?).

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Backyard domestication

There’s a “dump heap” hypothesis of agricultural origins which suggests that people first got interested in actively managing and manipulating plants for food or other products when they saw them sprouting out of piles of garbage in and about settlements. There they could observe them daily and experiment with them. A slight variation on this theme — involving corrals in pastoralist campsites rather than garbage dumps — has been proposed for the domestication of quinoa.

One of the things that might have happened in these fertile micro-environments in close proximity to human habitations is that different related species might have been brought accidentally together, leading to hybridization and the development of interesting new — polyploid — types. But there really hasn’t been much empirical evidence for this.

No more. A new paper ((Colin E. Hughes, Rajanikanth Govindarajulu, Ashley Robertson, Denis L. Filer, Stephen A. Harris, and C. Donovan Bailey. Serendipitous backyard hybridization and the origin of crops. PNAS published August 17, 2007, 10.1073/pnas.0702193104.)) looks at the domestication of the legume tree Leucaena in Mexico, where it is grown for food (it is also used as a fodder in some parts of the world). A variety of evidence is discussed which suggests that there has indeed been much hybridization among up to 13 different wild species of Leucaena in Mexican backyards. This has proved “a potent trigger for domestication.” The authors think a similar thing also happened in Mexico with two other perennial crops, Agave and Opuntia.

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Solanaceous information

There’s a global online monograph of the genus Solanum called Solanaceae Source. Each species treatment includes illustrations, a clickable list of specimens, links to molecular data and a dot distribution map (which mashes herbarium specimen locality data with Google Maps), among other things. The National Science Foundation (NSF) funds the project as part of the Planetary Biodiversity Inventories mission. Collaborators are eligible for small awards in support of their contributions to the completion of the worldwide Solanum monograph.

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Wild relatives to the rescue (again)

You may remember the recent warnings about a new strain of wheat stem rust called Ug99 making its way from the Rift Valley of Africa across the Red Sea to Yemen, thus threatening the very home of wheat in the Middle East. Jeremy blogged about it a couple of months back. Well, resistance to the disease has now been found in about 70% of the 100-odd samples of a wild wheat (Aegilops sharonensis) collected in southern Lebanon and Israel, according to a paper in Plant Disease. Four of the samples actually have resistance to a whole range of fungal diseases:

Co-author of the paper, Yehoshua Aniksterat, of the Israel-based Institute for Cereal Crops Improvement at Tel Aviv University, told SciDev.Net that although it could be difficult — and take up to five years or more — they may be able to transfer genes from wild to cultivated wheat.

The map below is what GBIF knows about the geographic distribution of A. sharonensis ((Israel Nature and Parks Authority, Israel Nature and Parks Authority (accessed through GBIF data portal, http://data.gbif.org/datasets/resource/1431, 2007-08-14) US National Plant Germplasm System, United States National Plant Germplasm System Collection (accessed through GBIF data portal, http://data.gbif.org/datasets/resource/1429, 2007-08-14).)).

sharonensis.jpg