Persistence of an endangered native duck,feral mallards,and multiple hybrid swarms across the main Hawaiian Islands

Interspecific hybridization is recognized as an important process in the evolutionary dynamics of both speciation and the reversal of speciation. However, our understanding of the spatial and temporal patterns of hybridization that erode versus promote species boundaries is incomplete. The endangered, endemic koloa maoli (or Hawaiian duck, Anas wyvilliana) is thought to be threatened with genetic extinction through ongoing hybridization with an introduced congener, the feral mallard (A. platyrhynchos). We investigated spatial and temporal variation in hybrid prevalence in populations throughout the main Hawaiian Islands, using genomic data to characterize population structure of koloa, quantify the extent of hybridization, and compare hybrid proportions over time. To accomplish this, we genotyped 3,308 double‐digest restriction‐site‐associated DNA (ddRAD) loci in 425 putative koloa, mallards, and hybrids from populations across the main Hawaiian Islands. We found that despite a population decline in the last century, koloa genetic diversity is high. There were few hybrids on the island of Kaua?i, home to the largest population of koloa. By contrast, we report that sampled populations outside of Kaua?i can now be characterized as hybrid swarms, in that all individuals sampled were of mixed koloa × mallard ancestry. Further, there is some evidence that these swarms are stable over time. These findings demonstrate spatial variation in the extent and consequences of interspecific hybridization, and highlight how islands or island‐like systems with small population sizes may be especially prone to genetic extinction when met with a congener that is not reproductively isolated.     

How important are the common factors in psychotherapy? An update

The common factors have a long history in the field of psychotherapy theory, research and practice. To understand the evidence supporting them as important therapeutic elements, the contextual model of psychotherapy is outlined. Then the evidence, primarily from meta‐analyses, is presented for particular common factors, including alliance, empathy, expectations, cultural adaptation, and therapist differences. Then the evidence for four factors related to specificity, including treatment differences, specific ingredients, adherence, and competence, is presented. The evidence supports the conclusion that the common factors are important for producing the benefits of psychotherapy.     

Uredo maua, sp. nov., andUromyces tairae: Additions to the rust flora of Hawai'i

Uredo maua, onXylosma hawaiiense (Flacourtiaceae), an endemic tree of Hawaiian forests, is newly described as an addition to Hawai'i's native rust flora.Uredo wakensis, originally described from Wake Island and reported from other Pacific islands onTournefortia argentea (Boraginaceae), represents the uredinial state ofUromyces tairae, described from Okinawa. This rust is newly reported from Hawai'i.     

Population variation and hybridization: Comparison of finches from two archipelagos

Summary Some populations of Darwin's Finches (Emberizinae) are exceptionally variable in body size and beak traits as a result of introgressive hybridization. A study of museum specimens of honeycreeper-finches (Carduelinae) from the Hawaiian islands was undertaken to see if the same phenomenon was manifested by a different phyletic group of finches in a different archipelago. Five hundred and twenty-four specimens of the seven species with finch-like bills were measured and their coefficients of variation were compared with those of the ground finch group (six species) of Darwin's Finches. Coefficients were smaller in the Hawaiian finches. Sympatric and, hence, potentially hybridizing species on the island of Hawaii were not consistently more variable than the allopatric species on other islands in the archipelago. The one species with both sympatric and allopatric populations did not show greater variation in the sympatric population. There is little evidence from these comparisons of hybridization occurring in the last 100 years. The difference between the two finch faunas can be explained in terms of two factors. Finches have been present for a longer time in the Hawaiian archipelago than in the Galápagos archipelago and have had more time to not only diversify but to evolve pre- and post-zygotic isolating mechanisms. In the generally less seasonal and floristically richer Hawaiian islands they have evolved greater dietary specializations. Beak traits adapted to specialist feeding may have been under stronger stabilizing selection and hybrids (if formed) may have been at a strong disadvantage in the absence of an ecological niche intermediate between the niches of the two parental species. Results of published electrophoretic studies of genetic variation suggest that the early phase of differentiation, involving occasional introgressive hybridization, may last for up to 5 million years.     

ANNUAL REPRODUCTIVE CYCLE OF THE FEMALE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)

Abstract: The annual reproductive cycle is described for the adult female Hawaiian monk seal ( Monachus schauinslandi ) from data collected at Laysan Island (1982–1991) and Lisianski Island (1982–1983) in the Northwestern Hawaiian Islands. Pupping, lactation, weaning, and molting were directly observed, while mating was rarely observed and was, therefore, inferred from the occurrence of mounting injuries and from adult male and female association patterns. Pooled birth rates during the study period were 0.544 for all adult-sized females and 0.675 for females parous in earlier years. For parturient females, pupping peaked in late March and early April, weaning in May, mounting injuries in May and June, and molting in July. For non-parturient females, the median mounting injury and molting dates occurred 17 and 28 days earlier, respectively. Pupping date set the timing of subsequent events in the annual cycle, but the timing of those events was adjusted by loss of the pup or poor physical condition of the female. Individual pupping patterns varied widely. The mean interval for births in consecutive years was 381 days; females that pupped in consecutive years gave birth later each season. Conversely, females who skipped a year or more gave birth earlier their next pupping season.     

Natural selection of the major histocompatibility complex (Mhc) in Hawaiian honeycreepers (Drepanidinae)

The native Hawaiian honeycreepers represent a classic example of adaptive radiation and speciation, but currently face one the highest extinction rates in the world. Although multiple factors have likely influenced the fate of Hawaiian birds, the relatively recent introduction of avian malaria is thought to be a major factor limiting honeycreeper distribution and abundance. We have initiated genetic analyses of class II beta chain Mhc genes in four species of honeycreepers using methods that eliminate the possibility of sequencing mosaic variants formed by cloning heteroduplexed polymerase chain reaction products. Phylogenetic analyses group the honeycreeper Mhc sequences into two distinct clusters. Variation within one cluster is high, with dN > dS and levels of diversity similar to other studies of Mhc (B system) genes in birds. The second cluster is nearly invariant and includes sequences from honeycreepers (Fringillidae), a sparrow (Emberizidae) and a blackbird (Emberizidae). This highly conserved cluster appears reminiscent of the independently segregating Rfp-Y system of genes defined in chickens. The notion that balancing selection operates at the Mhc in the honeycreepers is supported by transpecies polymorphism and strikingly high dN/dS ratios at codons putatively involved in peptide interaction. Mitochondrial DNA control region sequences were invariant in the i'iwi, but were highly variable in the 'amakihi. By contrast, levels of variability of class II beta chain Mhc sequence codons that are hypothesized to be directly involved in peptide interactions appear comparable between i'iwi and 'amakihi. In the i'iwi, natural selection may have maintained variation within the Mhc, even in the face of what appears to a genetic bottleneck.     

Hybridization as a source of evolutionary novelty: leaf shape in a Hawaiian composite

Hybridization is increasingly recognized as a significant creative force in evolution. Interbreeding among species can lead to the creation of novel genotypes and morphologies that lead to adaptation. On the Hawaiian island of Oahu, populations of two species of plants in the endemic genus Lipochaeta grow at similar elevations in the northern Waianae Mountains. These two species represent extremes of the phenotypic distribution of leaf shape: the leaves of Lipochaeta tenuifolia individuals are compound and highly dissected while leaves of L. tenuis are simple. Based primarily on leaf shape morphology, a putative hybrid population of Lipochaeta located at Puu Kawiwi was identified. Individuals in this population exhibit a range of leaf shapes intermediate in varying degrees between the leaf shapes of the putative parental species. We analyzed individuals from pure populations of L. tenuifolia, L. tenuis and the putative hybrids using 133 AFLP markers. Genetic analysis of these neutral markers provided support for the hybrid origin of this population. The correlation between genetic background and leaf morphology in the hybrids suggested that the genome of the parental species with simple leaves might have significantly contributed to the evolution of a novel, compound leaf morphology.     

FORAGING OF JUVENILE MONK SEALS AT FRENCH FRIGATE SHOALS, HAWAII

Emaciation and poor survivorship of juvenile Hawaiian monk seals at French Frigate Shoals atoll prompted a study of their foraging, using video camera technology ( crittercam ). Nine juveniles between the ages of 1 and 3 yr (six males, three females) were fitted with crittercam to identify their foraging habitat and feeding behavior. All feeding was directed at small (≤ 10 cm), cryptic, benthic prey. Older seals (ages 2 and 3), varied in their foraging intensity with most of their attention directed at shallow atoll depths (10–30 m). In contrast, the three yearlings focused all their feeding in the sand fields (50–100 m) on the atoll's outer slope. Bottom trawls were used to assess the prey abundance of the sand habitat and found 70% of the numerical catch was flounder ( Bothidae ). Extrapolating the yearlings' prey capture rate (0.13/min, derived from the crittercam video) over their total bottom time yielded an estimated 1–1.3 kg/day of flounder. The mean size of flounder (5 ± 1.7 cm) caught in the bottom trawls was close to the size at which larval flounder settle from the plankton (3 cm), suggesting that localized changes in oceanography could directly impact the seals' prey supply. Extensive use of sand communities by young seals may be the strongest link yet identified between juvenile survivorship and oceanographic dynamics.     

Climate‐associated population declines reverse recovery and threaten future of an iconic high‐elevation plant

Although climate change is predicted to place mountain‐top and other narrowly endemic species at severe risk of extinction, the ecological processes involved in such extinctions are still poorly resolved. In addition, much of this biodiversity loss will likely go unobserved, and therefore largely unappreciated. The Haleakalā silversword is restricted to a single volcano summit in Hawai‘i, but is a highly charismatic giant rosette plant that is viewed by 1–2 million visitors annually. We link detailed local climate data to a lengthy demographic record, and combine both with a population‐wide assessment of recent plant mortality and recruitment, to show that after decades of strong recovery following successful management, this iconic species has entered a period of substantial climate‐associated decline. Mortality has been highest at the lower end of the distributional range, where most silverswords occur, and the strong association of annual population growth rates with patterns of precipitation suggests an increasing frequency of lethal water stress. Local climate data confirm trends toward warmer and drier conditions on the mountain, and signify a bleak outlook for silverswords if these trends continue. The silversword example foreshadows trouble for diversity in other biological hotspots, and illustrates how even well‐protected and relatively abundant species may succumb to climate‐induced stresses.