Catastrophic Floods May Pave the Way for Increased Genetic Diversity in Endemic Artesian Spring Snail Populations

The role of disturbance in the promotion of biological heterogeneity is widely recognised and occurs at a variety of ecological and evolutionary scales. However, within species, the impact of disturbances that decimate populations are neither predicted nor known to result in conditions that promote genetic diversity. Directly examining the population genetic consequences of catastrophic disturbances however, is rarely possible, as it requires both longitudinal genetic data sets and serendipitous timing. Our long-term study of the endemic aquatic invertebrates of the artesian spring ecosystem of arid central Australia has presented such an opportunity. Here we show a catastrophic flood event, which caused a near total population crash in an aquatic snail species (Fonscochlea accepta) endemic to this ecosystem, may have led to enhanced levels of within species genetic diversity. Analyses of individuals sampled and genotyped from the same springs sampled both pre (1988–1990) and post (1995, 2002–2006) a devastating flood event in 1992, revealed significantly higher allelic richness, reduced temporal population structuring and greater effective population sizes in nearly all post flood populations. Our results suggest that the response of individual species to disturbance and severe population bottlenecks is likely to be highly idiosyncratic and may depend on both their ecology (whether they are resilient or resistant to disturbance) and the stability of the environmental conditions (i.e. frequency and intensity of disturbances) in which they have evolved

The effect of a single burn event on the aquatic invertebrates in artesian springs

Fire can often occur in aquatic ecosystems, which may affect aquatic invertebrates. Despite the importance of aquatic invertebrates to ecosystem function, the effect of fire on these environments has been little studied. We studied the effects of fire o

Supplement 1. An R package for fitting zero-inflated binomial models to biological survey data.

<h2>File List</h2><blockquote> <p><a href="obserr_0.3-1.zip">obserr_0.3-1.zip</a> <br> <a href="obserr_0.3-1.tar.gz">obserr_0.3-1.tar.gz</a></p></blockquote><h2>Description</h2><blockquote> <p>This is an add-on package for the statistical system R, used to fit zero-inflated binomial distributions to biological survey data by maximum-likelihood estimation. It is known to work with all versions of R above 1.5.0. R can be downloaded from the <a href="http://www.r-project.org/">R Project for Statistical Computing</a> . obserr_0.3-1.zip is a "compiled" package ready for installation in R running under Microsoft Windows, while obserr_0.3-1.tar.gz is a "source" package that requires the R source code development tools for installation, but can be installed in R under any operating system. </p> <p> In both archives, the source code for all functions is in obserr\R\obserror.R, and html formatted documentation for all functions is available in the zip archive under obserr\chm\*.html. Documentation is also present in the tar and gzip'ed archive, but it is in R documentation format, which can be processed into a variety of formats using the R source development tools.</p> <p>Under R for Windows, install the downloaded package using the Packages|Install package from local zip file... menu item. Once installed, the functions and associated documentation are made available in a session using the Packages|Load package menu command, or by typing library(obserr) at the command prompt. The documentation on the functions can be accessed either through the HTML index from the R for Windows Help menu, or by typing help(obs.error) at the command prompt after loading the package.</p> </blockquote

Circadian rhythm of behavioral thermoregulation in the sleepy lizard (Tiliqua rugosa)

Copyright © 2006 The Herpetologists' LeagueThe daily rhythm of behavioral thermoregulation in sleepy lizards (Tiliqua rugosa) was studied in laboratory thermal gradients under a 12L&ratio;12D photoperiod in autumn and spring. In both seasons, lizards showed distinctive daily rhythms of behavioral thermoregulation, selecting their highest body temperatures during the late photophase and lowest ones during the late scotophase or early photophase. When lizards were subjected to a period of constant darkness at both seasons, this rhythm persisted and free-ran with a period of 24.7 h, indicating that it is an endogenous circadian rhythm. Furthermore, the expression of this circadian rhythm varies seasonally in the amplitude of its free-running rhythm and in the phase at which the minimum Tb is selected during 12L&ratio;12D. The seasonal variation in the expression of the circadian rhythm of behavioural thermoregulation in Tiliqua rugosa lizards is likely to reflect seasonal changes in the neural regulation of this rhythm.David J. Ellis, Bruce T. Firth, Ingrid Bela