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Western Monarch butterflies (Danaus plexippus) migrate from inland breeding ranges to coastal overwintering grounds in California. Given that migratory individuals may make multi-scale habitat selection decisions, we considered a multi-scale species distribution model (SDM) using range-wide climatic and local landscape-level predictors of migratory and overwintering habitat and community-science presence data. The range-wide model output was included as a predictor in the local-scale model, generating multi-scale habitat suitability. The top range-wide predictor was the minimum temperature in December, contributing 83.7% to the model, and was positively associated with presence. At the local scale, the strongest predictors of presence were the range-wide output and percent coverage of low and medium levels of development, contributing > 95%, with 61–63% from the range-wide output, with local-scale suitability coinciding with the California coastal zones. Development's positive association with overwintering monarch presence was counterintuitive. It is likely that our local-scale model is overfit to these development zones, but it is unclear whether this overfitting resulted from modeler choices, monarchs overwintering close to human development, biased detection near human development, or a combination of these factors. Therefore, alternative approaches to collecting local-scale attribute data are suggested while recognizing the primacy of climate in restricting overwinter sites. [ABSTRACT FROM AUTHOR]

The Morro Bay kangaroo rat Dipodomys heermanni morroensis is a small, nocturnal, burrowing rodent endemic to the vicinity of Morro Bay in San Luis Obispo County, California. It was listed as endangered pursuant to the U.S. Endangered Species Act in 1973. Despite many searches over three decades, the Morro Bay kangaroo rat has not been captured or sighted in the wild since 1986. While recognizing that the Morro Bay kangaroo rat may be extinct, two of us in a previous paper also speculated it may be persisting at extremely low density in isolated colonies and recommended surveying with wildlife scent-detection dogs and baited camera traps. We searched with a wildlife scent-detection dog and baited camera traps in four historically occupied areas and detected no Morro Bay kangaroo rats. Unfortunately, our data combined with all other existing data do not allow us to conclude whether the Morro Bay kangaroo rat is extinct or extant. Essentially, the International Union for the Conservation of Nature international standard has not been met to make a definitive determination of extinction. That is, a species should be considered extinct only when there is no reasonable doubt that the last individual has died. We acknowledge that because of resource limitation we surveyed only a small sample of the numerous patches of habitat in the expansive landscape. Further, we now consider the Morro Bay sand spit (total area 4.35 km2, foredunes 3.75 km2), a peripheral area, as potentially part of the geographic range with suitable habitat, and it has never been searched. Therefore, considering all available information, we conclude that the Morro Bay kangaroo rat must be considered as possibly extant. We recommend that search efforts continue in several specific areas, including the Morro Bay sand spit. If the Morro Bay kangaroo rat still exists, it will be challenging and difficult to rediscover because of its likely low density and patchy distribution in the expansive landscape, combined with its small size, nocturnal nature, and secretive lifestyle. [ABSTRACT FROM AUTHOR]

Chiasmata are necessary for proper chromosomal segregation, but can result in inadvertent recombination. Bernstein and Michod demonstrated that meiosis evolved as a means of error correction, not genetic mixing. Therefore meiotic recombination is not the sine qua non of sex, but is instead an epiphenomenon of imperfect meiotic error correction. By correcting against recombinant genotypes, meiosis reduces recombination load, thereby providing an unappreciated selective advantage for sex. Sex reducing recombination load should be integrated into population genetic models of multi-locus epistasis for maintenance of sex and may explain sequestration of germ lines in animals. We predict that eumetazoa have less recombination load than sexual organisms without a germ line. Mitosis largely lacks the error correction of meiosis, destroys linkage through ubiquitous mitotic recombination, and thereby increases recombination load, especially in co-adapted gene complexes. Meiosis and possibly karyogamy provide an unexpected benefit to sex, offsetting at least some of the famed costs of sex. [ABSTRACT FROM AUTHOR]

We used molecular genetic analysis to assess the identification of two bird specimens otherwise difficult to identify with certainty. A Calidris sandpiper collected in 1974 had been identified at various times as the Little Stint (C. minuta) or as the Red-necked Stint (C. ruficollis). The remains of a booby salvaged in 2013 were identified as either the Nazca (Sula granti) or the Masked (S. dactylatra). We were able to identify the first as C. minuta and the second as S. granti, providing the first California records of each species. [ABSTRACT FROM AUTHOR]

The Mediterranean fruit fly, Ceratitis capitata, is a devastating agricultural pest that threatens to become established in vulnerable areas such as California and Florida. Considerable controversy surrounds the status of Californian medfly infestations: Do they represent repeated introductions or the persistence of a resident population? Attempts to resolve this question using traditional population genetic markers and statistical methods are problematic because the most likely source populations in Latin America were themselves only recently colonized and are genetically very similar. Here, significant population structure among several New World medfly populations is demonstrated through the analysis of DNA sequence variation at four intron loci. Surprisingly, in these newly founded populations, estimates of population structure increase when measures of subdivision take into account the relatedness of alleles as well as their frequency. A nonequilibrium, likelihood-based statistical test that utilizes multilocus genotypes suggests that the sole medfly captured in California during 1996 was introduced from Latin America and was less likely to be a remnant of an ancestral Californian population. Many bioinvasions are hierarchical in nature, consisting of several sequential or overlapping invasion events, the totality of which can be termed a metainvasion. Phylogenetic data from multilocus DNA sequences will be vital to understanding the evolutionary and ecological processes that underlie metainvasions and to resolving their constituent levels.