<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Habitat fragmentation can bring about a variety of gene-flow alterations in plant populations, potentially threatening adaptive potential and local persistence. It is expected that following habitat fragmentation an increased level of inbreeding will be evident. In addition, a reduction in genetic diversity and increased genetic differentiation is expected following severe or long term population bottlenecks. We examined population genetic parameters for the subtropical rainforest tree <italic>Macadamia tetraphylla</italic> (Proteaceae) at six field sites throughout its recently fragmented range, using four microsatellite loci. Genetic diversity (<italic>H</italic><sub>E</sub>) of the juvenile cohort was significantly correlated with estimated population size. No significant difference was observed for genetic diversity between adult and juvenile cohorts, but juveniles, and not adults, exhibited significant population differentiation (θ =0.061; <italic>P</italic>&lt;0.0001 and θ =0.016; <italic>P</italic>=0.23, respectively). A second, standardised measure of differentiation, ×′, yielded similarly large differences between the two cohorts, though higher estimates of differentiation overall (adults – θ′=0.034, juveniles – θ′=0.116). The coefficient of population inbreeding (<italic>f</italic>) was significant and positive in all juvenile, and four out of six adult, populations, and was significantly positively correlated with adult tree density, but not adult population size. Since fragmentation is relatively recent for this species, the population bottleneck must have been quite severe to have produced the observed patterns of population differentiation and genetic diversity. Fragmentation of forest across the study area over the last 100+ years has led to the genetic isolation of <italic>M. tetraphylla</italic> populations resulting in increased population divergence and likely eventual loss of genetic variation in future generations.</p></abstract>

Habitat fragmentation can bring about a variety of gene-flow alterations in plant populations, potentially threatening adaptive potential and local persistence. It is expected that following habitat fragmentation an increased level of inbreeding will be evident. In addition, a reduction in genetic diversity and increased genetic differentiation is expected following severe or long term population bottlenecks. We examined population genetic parameters for the subtropical rainforest tree Macadamia tetraphylla (Proteaceae) at six field sites throughout its recently fragmented range, using four microsatellite loci. Genetic diversity (HE) of the juvenile cohort was significantly correlated with estimated population size. No significant difference was observed for genetic diversity between adult and juvenile cohorts, but juveniles, and not adults, exhibited significant population differentiation (θ =0.061; P<0.0001 and θ =0.016; P=0.23, respectively). A second, standardised measure of differentiation, ×′, yielded similarly large differences between the two cohorts, though higher estimates of differentiation overall (adults – θ′=0.034, juveniles – θ′=0.116). The coefficient of population inbreeding (f) was significant and positive in all juvenile, and four out of six adult, populations, and was significantly positively correlated with adult tree density, but not adult population size. Since fragmentation is relatively recent for this species, the population bottleneck must have been quite severe to have produced the observed patterns of population differentiation and genetic diversity. Fragmentation of forest across the study area over the last 100+ years has led to the genetic isolation of M. tetraphylla populations resulting in increased population divergence and likely eventual loss of genetic variation in future generations.

Genetic consequences of subtropical rainforest fragmentation on <italic>Macadamia tetraphylla</italic> (Proteaceae)

Australian Centre for Evolutionary Biology and Biodiversity, and School of Earth and Environmental Sciences

State Herbarium of South Australia, Science Resource Centre, Department of Environment and Natural Resources

Silvae Genetica

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Genetic consequences of subtropical rainforest fragmentation on  (Proteaceae)

Habitat fragmentation can bring about a variety of gene-flow alterations in plant populations, potentially threatening adaptive potential and local...

Genetic consequences of subtropical rainforest fragmentation on Macadamia tetraphylla (Proteaceae)

Publié en ligne: 05 août 2017

Pages: 241 - 249

Reçu: 04 déc. 2010

DOI: https://doi.org/10.1515/sg-2011-0032

Mots clés
subtropical rainforest, fragmentation, gene diversity, inbreeding coefficient, differentiation, microsatellites

© 2011 C. S. Spain et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Genetic consequences of subtropical rainforest fragmentation on Macadamia tetraphylla (Proteaceae)

Publié en ligne: 05 août 2017

Pages: 241 - 249

Reçu: 04 déc. 2010

DOI: https://doi.org/10.1515/sg-2011-0032

Mots cléssubtropical rainforest, fragmentation, gene diversity, inbreeding coefficient, differentiation, microsatellites

© 2011 C. S. Spain et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Mots clés
subtropical rainforest, fragmentation, gene diversity, inbreeding coefficient, differentiation, microsatellites