Evol Ecol Res 3: 861-872 (2001)     Full PDF if your library subscribes.

Effect of habitat fragmentation on the genetic structure of the narrow endemic Brongniar tia vazquezii

Jorge González-Astorga1 and Juan Núñez-Farfán2

1Jardín Botánico Clavijero, Instituto de Ecología, A.C., km 2.5 An tigua Carretera a Coatepec, Xalapa 91000, Veracruz and 2Departamento de Ecología E volutiva, Instituto de Ecología, UNAM, Apartado Postal 70275, C.P. 04510 D.F., México

Author to whom all correspondence should be addressed.
e-mail: astorga@ecologia.ed u.mx


The monoecious, animal-pollinated shrub Brongniartia vazquezii is an endemic and endangered species of the tropical dry forests of Central Mexico. Deforestation of the tropical dry forest has fragmented the habitat and resulted in the isolation of the only four extant populations of B. va zquezii. In this study, we assessed the genetic consequences of habitat fragmentation by comparin g the genetic variability (allelic richness and expected mean heterozygosity, He), gene flow and population differentiation in both adult (before fragmentation) and seedling (after fr agmentation) populations. Six polymorphic enzymatic loci were used to estimate genetic parameters. F-statistics revealed a deficiency of heterozygous plants in both adults and seedlings in al l populations. This probably results from geitonogamous selfing. Genetic diversity was lower in adul t than in seedling populations (He = 0.201 and 0.357, respectiv ely). Significant genetic differentiation among populations and of similar magnitude was detected fo r the adult and seedling populations (Fst = 0.1013 and 0.0705, respectively). Average gene flow between pairs of reproductive populations was high (Nm = 2.23). The genetic structure of adult and seedling populations of B. vazquezii suggests that habitat fragmentation has not reduced, as yet, allelic richness and genetic diversity , nor has it increased genetic differentiation. Furthermore, high levels of gene flow were found, su ggesting that habitat fragmentation has broken the former population structure.

Keywords: Brongniartia vazquezii, conservation genetics, endemic and narrow species, gene flow, genetic structure, habitat fragmentation, Mexico.

IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.


        © 2001 Jorge González-Astorg a. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.