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Causes for genomic and morphological similarities among recently radiated species are often multifaceted and are further convoluted among species that readily interbreed. Here, we couple genomic and morphological trait comparisons to test the extent that ancestry and gene flow explain the retention of mallard-like traits within a sister species, the Mexican duck. First, we confirm that these taxa remain genetically structured, and that Mexican ducks exhibit an isolation-by-distance pattern. Despite the assumption of wide-spread hybridization, we found only a few late-stage hybrids, all from the southwestern USA. Next, assessing 23 morphological traits, we developed a genetically-vetted morphological key that is > 97% accurate in distinguishing across sex-age cohorts of Mexican ducks, mallards, and hybrids. During key development, we determined that 25% of genetically pure, immature male Mexican ducks of the northern population naturally displayed mallard-like traits in their formative plumage. In fact, applying this key to 55 museum specimens, we identified that only four of the 14 specimens originally classified as phenotypic hybrids were truly hybrids. We discuss how genomic and morphological comparisons shed light into the mechanism(s) underlying the evolution of complex phenotypic traits in recent radiations, and how misunderstanding the true morphological diversity within Mexican ducks resulted in taxonomic revisions that hindered conservation efforts.

Species range expansions and contractions can have ecological and genetic consequences, and thus are important areas of study for conservation. Hybridization and introgression are not uncommon in closely related populations that experience secondary contact during a range expansion. Allen’s Hummingbird (Selasphorus sasin) in California comprises two subspecies: the migratory S. s. sasin, which winters in central Mexico and breeds in central and northern California, and the resident S. s. sedentarius, which lives and breeds year-round on several of the Channel Islands off the California coast. Within recent decades, Allen’s Hummingbirds have been found living and breeding year-round in the southern California peri-urban mainland near Los Angeles. Ornithologists assumed that the L.A. birds were an expansion of the island subspecies, S. s. sedentarius due to similar but very subtle morphological characteristics. However, the genetic relationships among the three putative populations of Allen's hummingbird—migratory, southern California mainland, and island—are unknown. We investigated these relationships by analyzing variation of single nucleotide polymorphisms from the three geographic regions where S. sasin are present. Our population genomic analyses indicate that S. sasin hummingbirds inhabiting mainland southern California are a hybrid population resulting from admixture between S. s. sasin and S. s. sedentarius. From one perspective, these results may be interpreted as a positive development for S. s. sasin as the growing population represent an overall increase in the S. sasin population, and the expanding population contains a significant representation of S. s. sasin alleles.

Abstract: This paper reports on a bat survey conducted in November 2011 in Mangolo Nature Park and Rawa Aopa Watumohai National Park, both lowland forests located in Southeast Sulawesi. We recorded 22 species of bats that represents nearly 1/3 of the total bat species known to occur on Sulawesi. Three of these are endemic to Sulawesi and adjacent islands, whereas one species, Myotis cf. ridleyi was identified as a new distributional record for this island and with further investigation could prove to be an undescribed species. Our record of Chironax melanocephalus tumulus provided a range extension to the southeastern arm of Sulawesi. Two specimens of Hipposideros boeadii were topotypes and represent the first collections after the description of the type specimen. Collections of Rhinolophus arcuatus from this survey were only the second record of this species from island and represent a range extension. Specimens of Megaderma spasma celebensis were the first records of this species from Southeast Sulawesi. Species are discussed individually with external, cranial and dental measurements summarized. Based on this survey, the number of bat species now documented from the lowlands of Southeast Sulawesi represents the highest diversity yet recorded from a site on Sulawesi. This region is therefore a high priority for conservation and a hotspot for bat research in Indonesia, especially Sulawesi.

In 2001, roof rats were identified as major predators of open-cup songbird nests in old growth riparian forests of California’s Central Valley. Nest predation was as high as 80%. For some bird species in recent years, the populations had declined, and their range was reduced. A management strategy to reduce rat impacts on songbirds was considered a priority. Following a review of the literature and consultation with land managers and experts in rodent management and bird conservation, we decided to reduce rat populations with poison baits delivered in bait stations immediately prior to the songbird nesting period. We subsequently conducted studies to provide information on rat home range and habitat use, potential baits, optimal bait station placement and distribution, and the potential non-target hazards of the program. The management strategy was then implemented in one riparian forest tract in October - December 2003. This is an adaptive management approach that will be evaluated in 2004, modified as necessary, and if successful, potentially applied to other riparian forests. In this paper we describe our approach to developing the management strategy, provide preliminary results, and discuss some of the potential problems with its implementation on a large scale.