Congruence between environmental parameters, morphology and genetic structure in Australia’s most widely distributed eucalypt, Eucalyptus camaldulensis

Abstract

Eucalyptus camaldulensis is one of the most widely utilised eucalypts. It is also the only eucalypt that occurs across the Australian continent, playing a key ecological role as fauna habitat and in riverbank stabilisation. Despite its ecological and economic importance, uncertainty remains regarding the delineation of genetic and morphological variants. Nine hundred and ninety trees from 97 populations, representing the species' geographic range were genotyped using 15 microsatellite loci and patterns of diversity compared with restriction fragment length polymorphisms in 29 of these populations. Both markers showed that despite having a riverine distribution, downstream seed dispersal has had less influence than geographic distance on dispersal patterns. Spatial patterns in the distribution of microsatellite genotypes were compared with environmental parameters and boundaries defined by river systems, drainage basins and proposed subspecies. Significant genetic differences among populations within river systems indicated that rivers should not be treated as a single genetic entity in conservation or breeding programmes. Strong geographic trends were evident with 40% of variation in genetic diversity explained by latitude and moisture index. Isolation by distance and significant correlations between genetic distance and environmental parameters for most loci suggest historical factors have had more influence than selection on current patterns of distribution of genetic diversity. Geographic structuring of molecular variation, together with congruence between genetic and morphological variation indicate that E. camaldulensis should be treated as a number of subspecies rather than a single variable taxon. High levels of genetic diversity and geographic trends in the distribution of variation provide a firm basis for further exploration of the species' genetic resources.

Population genetic analysis and phylogeny reconstruction in Eucalyptus (Myrtaceae) using high-throughput, genome-wide genotyping

“…The development of microsatellite primers for eucalypt taxa (Brondani et al 1998(Brondani et al , 2006Byrne et al 1996;Glaubitz et al 2001;Jones et al 2001;Ottewell et al 2005;Shepherd et al 2006;Steane et al 2001;Thamarus et al 2002) opened the door for reliable genome-wide genotyping of a relatively large number of samples. Microsatellite markers gave researchers the power to examine genetic relationships within and among populations of one (e.g., Butcher et al 2009;Elliott and Byrne 2003;Jones et al 2007;Payn et al 2008;Rathbone et al 2007;Walker et al 2009; see also Byrne 2008 and references therein) or a few closely related species (e.g., Holman et al 2003, Le et al 2009, Shepherd et al 2008. While microsatellites were developed initially for mapping and population genetic studies, Ochieng et al (2007b) found them helpful for phylogenetic resolution of eucalypt genera.…”

Increased Ratio of Electron Transport to Net Assimilation Rate Supports Elevated Isoprenoid Emission Rate in Eucalypts under Drought

“…E. camaldulensis ssp. obtusa is the most widespread eucalypt in subtropical Australia (Butcher et al, 2009). Exploiting this ecological contrast, we empirically tested the hypothesis that constitutive isoprenoid emission is driven by ATP and NADPH availability (Loreto and Sharkey, 1993;Niinemets et al, 1999) and could potentially compete for the same with carbon assimilation (Harrison et al, 2013;Morfopoulos et al, 2014).…”

Going nowhere fast: a review of seed dispersal in eucalypts

“…For example, the spread of E. camaldulensis as an invasive weed along perennial, seasonal and intermittent watercourses in South Africa has often been reported (see, for example, Rejmánek and Richardson 2011). However, genomic research on 990 trees from 97 E. camaldulensis populations across the natural distribution in Australia has shown that genetic similarity was greatest between the nearest populations, regardless of whether or not they occurred on the same river system (Butcher et al 2009).…”