Data from: Loss of genetic diversity and increased embryonic mortality in non-native lizard populations

Many populations are small and isolated with limited genetic variation and
high risk of mating with close relatives. Inbreeding depression is
suspected to contribute to extinction of wild populations, but the
historical and demographic factors that contribute to reduced population
viability are often difficult to tease apart. Replicated introduction
events in non-native species can offer insights into this problem because
they allow us to study how genetic variation and inbreeding depression are
affected by demographic events (e.g. bottlenecks), genetic admixture and
the extent and duration of isolation. Using detailed knowledge about the
introduction history of 21 non-native populations of the wall lizard
Podarcis muralis in England, we show greater loss of genetic diversity
(estimated from microsatellite loci) in older populations and in
populations from native regions of high diversity. Loss of genetic
diversity was accompanied by higher embryonic mortality in non-native
populations, suggesting that introduced populations are sufficiently
inbred to jeopardize long-term viability. However, there was no
statistical correlation between population-level genetic diversity and
average embryonic mortality. Similarly, at the individual level, there was
no correlation between female heterozygosity and clutch size, infertility
or hatching success, or between embryo heterozygosity and mortality. We
discuss these results in the context of human-mediated introductions and
how the history of introductions can play a fundamental role in
influencing individual and population fitness in non-native species.