Founder Effects and Exotic Variability - Alien Species and Evolution - page 46

Table 3.1. Genetic variability patterns for populations of
the common myna ( Acridotheres tristis ) in regions where
it is native and introduced. (Data from Baker and
Moeed 1987.)

Alleles Polymorphic Heterozygosity

per Locus Loci (%) (Average)

N ATIVE
India 1.43 31.5 0.05

I NTRODUCED
Australia 1.30 23.1 0.05

New Zealand 1.24 19.5 0.05

South Africa 1.15 12.9 0.03

Fiji 1.30 20.6 0.05

Hawaii 1.20 18.0 0.06

Genetic Variability among Alien Microorganisms
Microorganisms and fungi that cause disease in plants and animals also
show diverse patterns of genetic variability. However, RAPD analysis of
butternut canker ( Sirococcus clavigignenti-juglandacearum ), a fungal disease of
North American butternut ( Juglans cinerea ), shows complete lack of vari-
ation (Furnier et al. 1999).This indicates that it is a very recent introduc-
tion of a single fungal strain. Even so, it is proving highly virulent to but-
ternut trees. As we shall see in chapter 11, other fungal diseases show
much higher levels of genetic variability.

Genetic Variability and Invasiveness
Analyses of genetic variability thus show that alien species differ greatly
in variability and that low, as well as high, variability can contribute to
their invasive capabilities. Analyses of genetic variability can also reveal
other information. Cryptic species—forms that are genetically distinct
but were previously unrecognized—are being identified through such
analyses. DNA fingerprints can also help identify the source locations of
alien populations, a useful step in the search for potential biological con-
trol agents.We shall turn to these topics in the next chapter.