Several dominant mutations of the mouse agouti coat colour gene have pleiotropic effects that include obesity and a yellow coat. The Ay allele is caused by a large deletion that affects the expression of several contiguous genes. We show that three other obesity-associated agouti mutations, Aiy, Asy and Avy, are due to different molecular alterations that result in ubiquitous expression of a chimaeric RNA that encodes a normal agouti protein. The Aiy and Avy alleles are caused by insertion of an intracisternal A particle element 1 kb or 100 kb, respectively, upstream of agouti coding sequences. These results provide a model for other genes that show allele-specific imprinting, and demonstrate that molecular mechanisms typically responsible for activation of proto-oncogenes can also lead to other disease phenotypes.

The agouti coat color gene encodes a p e sing molecule that controls the production of yellow and black pigment by meanoytes hin hair follicles. Some agouti alleles affect the dorsum and ventrum independently, which has provided the basis for sp tion that agouti gene action in different regions of the body is controlled by distinct genetic lci that are closely linked. Using a combination ofcDNA cloning and RNA expression studies, we find that alternative isoforms of agouti mRNA contain different noncoding firstexons located 100 kb apart, whose patterns of expression indicate independent control by regulatory elements that are either ventral specific or hair cycle specific. These results demonstrate that the apparent genetic complexity of the agouti locus is explained by the existence of multiple regulatory elements exerting control over a single coding sequence and provide a conceptual basis for understanding differences in dorsal and ventral hair coloration in many mammal species. The ventral-specific agouti isoform represents an example of a transcript whose expression is restricted to ventral skin and provides an approach to investigate the mechanisms by which dorsal-ventral differences in gene expression are established and maintained.

The intentional translocation of animals is an important tool for species conservation and ecosystem restoration, but reported success rates are low, particularly for threatened and endangered species. Publication bias further distorts success rates because the results of successful translocations may be more likely to be published than failed translocations. We conducted the first comprehensive review of all published and unpublished translocations of herpetofauna in New Zealand to assess publication bias. Of 74 translocations of 29 species in 25 years, 35 have been reported in the published literature, and the outcomes of 12 have been published. Using a traditional definition of success, publication bias resulted in a gross overestimate of translocation success rates (41.7% and 8.1% for published and all translocations, respectively), but bias against failed translocations was minimal (8.3% and 6.8%, respectively). Publication bias against translocations with uncertain outcomes, the vast majority of projects, was also strong (50.0% and 85.1% for published and all translocations, respectively). Recent translocations were less likely to be published than older translocations. The reasons behind translocations were related to publication. A greater percentage of translocations for conservation and research were published (63.3% and 40.0%, respectively) than translocations for mitigation during land development (10.0%). Translocations conducted in collaboration with a university were more frequently published (82.7% and 24.4%, respectively). To account for some of this publication bias, we reassessed the outcome of each translocation using a standardized definition of success, which takes into consideration the species' life history and the time since release. Our standardized definition of translocation success provided a more accurate summary of success rates and allows for a more rigorous evaluation of the causes of translocation success and failure in large-scale reviews.

Agouti protein and agouti-related protein are homologous paracrine signalling molecules that normally regulate hair colour and body weight, respectively, by antagonizing signalling through melanocortin receptors. Expression of Agouti is normally limited to the skin, but rare alleles from which Agouti is expressed ubiquitously, such as lethal yellow, have pleiotropic effects that include a yellow coat, obesity, increased linear growth, and immune defects. The mahogany (mg) mutation suppresses the effects of lethal yellow on pigmentation and body weight, and results of our previous genetic studies place mg downstream of transcription of Agouti but upstream of melanocortin receptors. Here we use positional cloning to identify a candidate gene for mahogany, Mgca. The predicted protein encoded by Mgca is a 1,428-amino-acid, single-transmembrane-domain protein that is expressed in many tissues, including pigment cells and the hypothalamus. The extracellular domain of the Mgca protein is the orthologue of human attractin, a circulating molecule produced by activated T cells that has been implicated in immune-cell interactions. These observations provide new insight into the regulation of energy metabolism and indicate a molecular basis for crosstalk between melanocortin-receptor signalling and immune function.

Aim Invasive species are predicted to experience a reduction in genetic diversity during the introduction process because of founder effects, yet they are able to successfully establish in new regions and outcompete the native biota. Admixture has been proposed as a potential solution to this genetic paradox. We adopted a phylogeographic approach to investigate the invasion history of the delicate skink (Lampropholis delicata) in the Pacific region and test the hypothesis that admixture is important for the success of biological invasions.Location Eastern Australia and the Pacific region (Lord Howe Island, New Zealand, Hawaii).Methods We obtained mitochondrial DNA sequence data (ND2, ND4) from across the native Australian range (238 samples, 120 populations) and 371 samples from the introduced range of L. delicata. Genetic distances and Analysis of molecular variance (AMOVA) were used to examine the level of genetic variation across the native and introduced ranges.Results Fourteen haplotypes were evident in the introduced range (1 in Hawaii, 7 in New Zealand, 7 in Lord Howe Island), with a shared haplotype present in both New Zealand and Lord Howe Island. Five source regions were identified (Brisbane, Tenterfield, Border Ranges, Yamba-Coffs Harbour, Sydney) from across four distinct native-range genetic lineages. The Hawaiian population stems from a single introduction from Brisbane, whereas one or more introductions from the Tenterfield region led to the New Zealand populations. Multiple introductions from across all five source regions have resulted in extreme admixture (up to 8.3% sequence divergence) within Lord Howe Island.Main Conclusions L. delicata introductions are capable of being successful both in the presence and absence of admixture. Contrary to the predictions of the sequential two-step model, the presence of admixture was not related to the time since initial introduction. We suggest that the importance of admixture in determining the success of biological invasions has been overemphasized.

Climate change poses a particular threat to species with fragmented distributions and little or no capacity to migrate. Assisted colonization, moving species into regions where they have not previously occurred, aims to establish populations where they are expected to survive as climatic envelopes shift. However, adaptation to the source environment may affect whether species successfully establish in new regions. Assisted colonization has spurred debate among conservation biologists and ecologists over whether the potential benefits to the threatened species outweigh the potential disruption to recipient communities. In our opinion, the debate has been distracted by controversial examples, rather than cases where assisted colonization may be a viable strategy. We present a strategic plan for the assisted migration of tuatara (Sphenodon punctatus), an endemic New Zealand reptile. The plan includes use of extant populations as reference points for comparisons with assisted-colonization populations with respect to demography, phenotypic plasticity, and phenology; optimization of genetic variation; research to fill knowledge gaps; consideration of host and recipient communities; and inclusion of stakeholders in the planning stage. When strategically planned and monitored, assisted colonization could meet conservation and research goals and ultimately result in the establishment of long-term sustainable populations capable of persisting during rapid changes in climate.

Highlights d Inbreeding reduces lifetime fitness of critically endangered helmeted honeyeaters d Fitness costs are associated with both engaging in inbreeding and being inbred d Pairing with a genetically dissimilar mate reduces fitness costs of being inbred d Weak short-term effects of inbreeding can underlie stronger lifetime effects

Reduced genetic diversity can result in short-term decreases in fitness and reduced adaptive potential, which may lead to an increased extinction risk. Therefore, maintaining genetic variation is important for the short- and long-term success of reintroduced populations. Here, we evaluate how founder group size and variance in male reproductive success influence the long-term maintenance of genetic diversity after reintroduction. We used microsatellite data to quantify the loss of heterozygosity and allelic diversity in the founder groups from three reintroductions of tuatara (Sphenodon), the sole living representatives of the reptilian order Rhynchocephalia. We then estimated the maintenance of genetic diversity over 400 years (approximately 10 generations) using population viability analyses. Reproduction of tuatara is highly skewed, with as few as 30% of males mating across years. Predicted losses of heterozygosity over 10 generations were low (1-14%), and populations founded with more animals retained a greater proportion of the heterozygosity and allelic diversity of their source populations and founder groups. Greater male reproductive skew led to greater predicted losses of genetic diversity over 10 generations, but only accelerated the loss of genetic diversity at small population size (<250 animals). A reduction in reproductive skew at low density may facilitate the maintenance of genetic diversity in small reintroduced populations. If reproductive skew is high and density-independent, larger founder groups could be released to achieve genetic goals for management.