Christin L. Pruett

It's Not Easy Being Green: Wind Energy and a Declining Grassland Bird

The lesser prairie-chicken (Tympanuchus pallidicinctus) is an umbrella species for the short- and mixed-grass prairie ecosystem of the south-central United States. This species has suffered large population declines over the last century that mirror the loss of prairie. Populations have become increasingly fragmented, and habitat connections between populations are being severed. A possible new threat to lesser prairie-chickens is the rapid development of wind-energy facilities throughout their habitat. In addition to contributing to the loss of prairie, these facilities could serve as barriers to movement if birds avoid wind turbines and their associated power transmission lines. We summarize evidence for avoidance behavior in birds, propose connectivity areas between distributional cores, propose strategies for conservation of lesser prairie-chickens, and encourage lawmakers to adopt state and federal regulations on wind-farm placement. Without a concerted effort, lesser prairie-chickens and similar species are likely to disappear, as will the southern prairie on which they depend.

SEASONAL MIGRATION, SPECIATION, AND MORPHOLOGICAL CONVERGENCE IN THE GENUS CATHARUS (TURDIDAE)

Abstract The effects of seasonal migration on evolutionary change within lineages is poorly understood, in terms of both differentiation (cladogenesis) and specialization (anagenesis). Regarding differentiation, two contradictory hypotheses exist: Seasonal migration counters differentiation; or it can stimulate differentiation by exposing lineages to new environments. Regarding specialization, the morphological consequences of a migratory life history have not been well explored. We examined these issues by reconstructing morphological and molecular phylogenies of the genus Catharus (Turdidae), a group of forest-dwelling, New World thrushes traditionally considered to include a small “species flock” of Nearctic-Neotropic migrants. DNA sequence data (2,920–3,027 base pairs) do not support traditional taxonomy, and morphological characters conflicted with these data. Results suggest that long-distance seasonal migration arose independently four times in Catharus sensu lato (including Hylocichla mustelina). Correlated morphological evolution occurred among several characters in these lineages, and these shared traits may stem from ecological conditions in Nearctic forests. Migración Estacional, Especiación y Convergencia Morfológica en el Género Catharus (Turdidae)

VAINLY BEATING THE AIR: SPECIES-CONCEPT DEBATES NEED NOT IMPEDE PROGRESS IN SCIENCE OR CONSERVATION

Debate over species concepts has been a persistent theme in biology. We briefl y summarize competing species concepts and facets of the debate itself. We maintain that the inherent subjectivity within all species concepts is likely to ensure continued disagreement on where to place species limits. Although the debate itself contributes to the understanding of speciation and evolutionary processes, it can take on political overtones through posturing, caricatures, and provocative statements. Empirically, neither basic nor applied science would seem to have been slowed appreciably because the species-concept debate remains unresolved. Similarly, continued disagreement must be placed in its proper context (e.g., be shelved) when considering the preservation of biodiversity. To a considerable extent, this has occurred within the conservation community. The biological species concept (BSC) and its inclusion of diagnosably distinct populations as subspecies remain dominant in ornithology. This may be att ributable, in part, to the seemingly infi nitely fi ne divisions possible under phylogenetic species concepts (PSC)—which, among other things, could strain public credulity over what constitutes a species. Nevertheless, the strengths of each of these concepts are being applied to improve our understanding of biodiversity. The longstanding disagreement over species concepts should not become an impediment to responsible conservation and wildlife manage- ment. It probably has not occurred broadly yet, but there may be potential for such an eff ect in the political arena. Received, accepted. Resumen.—El concepto de especie es un tema polemico en biologia. Resumimos brevemente los distintos conceptos de especie y las facetas del debate. Consideramos que la subjetividad inherente en todos los conceptos de especie garantizan un continuo desacuerdo en como delimitar las especies. Aunque el debate en si mismo contribuye a entender el proceso de especiacion y otros procesos evolutivos, muchas veces se desarrolla en terminos demasiado caricaturescos, burlescos y provocativos. De hecho, la continuidad del debate no parece haber ralentizado ni la ciencia basica ni la aplicada. De igual modo, el continuo desacuerdo debe contextualizarse cuando consideramos la conservacion de la diversidad. El concepto biologico de especie (BSC) y la inclusion de las poblaciones diagnosticables como subespecies, sigue predominando en ornitologia. Esto puede deberse en parte a las infi nitas divisiones que se pueden realizar bajo el concepto fi logenetico de especie (PSC), lo que entre otras cosas, puede afectar el entendimiento del publico en general sobre que es una especie. Sin embargo, los puntos fuertes de cada concepto se estan aplicando para llegar a un mejor entendimiento de la biodiversidad. Este desacuerdo historico sobre el concepto de especie no tiene por que ser un impedimento para una politica responsable para la conservacion y gestion de la vida salvaje.

The effects of contemporary processes in maintaining the genetic structure of western song sparrows (Melospiza melodia)

Historic events and contemporary processes work in concert to create and maintain geographically partitioned variation and are instrumental in the generation of biodiversity. We sought to gain a better understanding of how contemporary processes such as movement and isolation influence the genetic structure of widely distributed vagile species such as birds. Song sparrows (Melospiza melodia) in western North America provide a natural system for examining the genetics of populations that have different patterns of geographic isolation and migratory behavior. We examined the population genetics of 576 song sparrows from 23 populations using seven microsatellite loci to assess genetic differentiation among populations and to estimate the effects of drift and immigration (gene flow) on each population. Sedentary, isolated populations were characterized by low levels of immigration and high levels of genetic drift, whereas those populations less isolated displayed signals of high gene flow and little differentiation from other populations. Contemporary dispersal rates from migratory populations, estimated by assignment test, were higher and occurred over larger distances than dispersal from sedentary populations but were also probably too low to counter the effects of drift in most populations. We suggest that geographic isolation and limited gene flow facilitated by migratory behavior are responsible for maintaining observed levels of differentiation among Pacific coastal song sparrow populations.

A parapatric propensity for breeding precludes the completion of speciation in common teal (Anas crecca, sensu lato)

Speciation is a process in which genetic drift and selection cause divergence over time. However, there is no rule dictating the time required for speciation, and even low levels of gene flow hinder divergence, so that taxa may be poised at the threshold of speciation for long periods of evolutionary time. We sequenced mitochondrial DNA (mtDNA) and eight nuclear introns (nuDNA) to estimate genomic levels of differentiation and gene flow between the Eurasian common teal (Anas crecca crecca) and the North American green‐winged teal (Anas crecca carolinensis). These ducks come into contact in Beringia (north‐eastern Asia and north‐western North America) and have probably done so, perhaps cyclically, since the Pliocene–Pleistocene transition, ∼2.6 Ma, when they apparently began diverging. They have diagnosable differences in male plumage and are 6.9% divergent in the mtDNA control region, with only 1 of 58 crecca and 2 of 86 carolinensis having haplotypes grouping with the other. Two nuclear loci were likewise strongly structured between these teal (Φst ≥ 0.35), but six loci were undifferentiated or only weakly structured (Φst = 0.0–0.06). Gene flow between crecca and carolinensis was ∼1 individual per generation in both directions in mtDNA, but was asymmetrical in nuDNA, with ∼1 and ∼20 individuals per generation immigrating into crecca and carolinensis, respectively. This study illustrates that species delimitation using a single marker oversimplifies the complexity of the speciation process, and it suggests that even with divergent selection, moderate levels of gene flow may stall the speciation process short of completion.

Divergence in an archipelago and its conservation consequences in Aleutian Island rock ptarmigan

The identification and assessment of island endemics is a conservation priority. We genotyped 115 rock ptarmigan from five insular populations in the Aleutian-Commander archipelago and two Alaska mainland populations to identify conservation units, assess genetic diversity and gene flow, and to determine whether populations have declined over time. We found four distinct populations that appear to be completely isolated and which correspond closely to recognized subspecies. The most geographically isolated populations also have the lowest genetic diversity. Three populations (Attu Island, Rat Islands, and Adak Island), which each experienced historic introductions of an exotic predator, showed genetic signals of declines, but the timing did not correspond with the introduction. We recommend management of each endemic group as a unique conservation unit.

Concordant and Discordant Signals Between Genetic Data and Described Subspecies of Pacific Coast Song Sparrows

Abstract Song Sparrows (Melospiza melodia) provide one of North Americas best examples of geographic variation in phenotype, with approximately 26 described subspecies recognized. However, researchers have found inconsistent signals when making comparisons between subspecies and genetic markers. We examined seven microsatellite loci from 576 Song Sparrows of 23 western North American populations representing 13 recognized subspecies. We assessed the level of concordance between microsatellite genotypes and subspecies. We found that in some, but not all, instances neutral genetic structure corresponded to recognized phenotypic structure. However, some populations not currently recognized as subspecies were found to be genetically differentiated from all other populations that are considered to be the same subspecies. We suggest that a combination of phenotypic characters, behavioral traits, and multiple loci be used when assessing geographic variation in birds, and that sampling should be conducted in more than one location within broadly distributed subspecies.

Fine-Scale Selection of Habitat by the Lesser Prairie-Chicken

Abstract Proper management of grasslands and shrublands requires an understanding of the factors that influence the persistence of organisms. We compare differences in vegetation between sites occupied by the lesser prairie-chicken (Tympanuchus pallidicinctus) and random sites to investigate composition of grasses and forbs and the importance of cover. We observed that birds selected habitat, at least in part, based on composition of grasses and forbs. There was generally a larger variance in diversity of plants for random sites compared to sites associated with presence of lesser prairie-chicken. The role of vegetative cover in selection of habitat is important for avoidance of predators, but use of cover also is a means of thermoregulation. Risk-sensitive behavior is a trade-off between avoiding predation and suitable microclimate. We report evidence that the lesser prairie-chicken consistently seeks to limit the risk of predation and selects locales with a favorable microclimate; birds select sites more or less exposed depending on apparent temperature. We infer that selection of habitat by the lesser prairie-chicken is the result of composition of species of plants, avoidance of predators, and thermoregulation, with the lekking mating system of this bird also playing a role. This declining species might face increasing threats as some practices of land management alter structure of vegetation and reduce shrub cover. Resumen El manejo adecuado de los pastizales y matorrales requiere una comprensión de los factores que influyen en la persistencia de los organismos. Se comparan las diferencias de vegetación entre sitios ocupados por el pollo de la pradera menor (Tympanuchus pallidicinctus) y sitios al azar para investigar la composición de pastos y hierbas y la importancia de la cubierta. Observamos que las aves seleccionaron el hábitat, al menos en parte, basándose en la composición de pastos y hierbas. En general hubo una variación mayor en la diversidad de la vegetación de los sitios al azar en comparación con los sitios asociados con la presencia del pollo de la pradera menor. El papel de la cubierta vegetal en la selección de hábitat es importante para evitar a los depredadores, pero el uso de la cubierta es también un medio de termorregulación. El comportamiento sensible al riesgo es una concesión mutua entre evitar la depredación y conseguir un microclima adecuado. Se presenta evidencia de que el pollo de la pradera menor constantemente trata de limitar el riesgo de depredación y de seleccionar lugares con un microclima favorable; las aves seleccionan los sitios más o menos expuestos dependiendo de la temperatura ambiental. Se infiere que la selección del hábitat del pollo de la pradera menor es el resultado de la composición de especies de plantas, de evitar a los depredadores, y de la termorregulación, con el sistema de apareamiento lek de esta ave también jugando un papel importante. Esta especie en declive puede encontrar amenazas crecientes debido a que algunas prácticas de manejo de la tierra alteran la estructura de la vegetación y reducen la cobertura de arbustos.

CHOLINESTERASE ACTIVITY IN WHITE-WINGED DOVES EXPOSED TO METHYL PARATHION

Captive white-winged doves (Zenaida asiatica) were exposed to various levels of methyl parathion (MP) in drinking water to determine effects on brain and blood cholinesterase (ChE) activity. We conducted two experiments to test the influence of MP dose (the amount of MP actually ingested), MP concentration (the amount of MP per unit water), and exposure duration (number of days exposed to a constant MP concentration) on ChE activity. Plasma ChE activity was not useful in predicting brain ChE activity. Methyl parathion concentration had a greater influence on plasma and brain ChE activity levels than dose or time of exposure. These results contribute to the evaluation of irrigation water as a route of exposure of wildlife to pesticides.

How migratory thrushes conquered northern North America: a comparative phylogeography approach.

Five species of migratory thrushes (Turdidae) occupy a transcontinental distribution across northern North America. They have largely overlapping breeding ranges, relatively similar ecological niches, and mutualistic relationships with northern woodland communities as insectivores and seed-dispersing frugivores. As an assemblage of ecologically similar species, and given other vertebrate studies, we predicted a shared pattern of genetic divergence among these species between their eastern and western populations, and also that the timing of the coalescent events might be similar and coincident with historical glacial events. To determine how these five lineages effectively established transcontinental distributions, we used mitochondrial cytochrome b sequences to assess genetic structure and lineage coalescence from populations on each side of the continent. Two general patterns occur. Hermit and Swainson’s thrushes (Catharus guttatus and C. ustulatus) have relatively deep divergences between eastern and western phylogroups, probably reflecting shared historic vicariance. The Veery (C. fuscescens), Gray-cheeked Thrush (C. minimus), and American Robin (Turdus migratorius) have relatively shallow divergences between eastern and western populations. However, coalescent and approximate Bayesian computational analyses indicated that among all species as many as five transcontinental divergence events occurred. Divergence within both Hermit and Swainson’s thrushes resembled the divergence between Gray-cheeked Thrushes and Veeries and probably occurred during a similar time period. Despite these species’ ecological similarities, the assemblage exhibits heterogeneity at the species level in how they came to occupy transcontinental northern North America but two general continental patterns at an among-species organizational level, likely related to lineage age.