Pacific Coast Populations Research Articles

Differences in life history patterns of American shad (Alosa sapi dissima) populations between ancestral, Atlantic coast, and non-native Pacific coast rivers of North America

Organisms naturalized outside their native range can reveal new life history patterns in new environments. Here, we compare life history patterns of American shad, Alosa sapidissima, from five rivers along the U.S. Pacific coast (introduced range) with contemporary data from the Atlantic coast source populations. The Pacific coast fish grew slower, matured at a younger age, and were less often iteroparous than conspecifics from the Hudson River and Susquehanna River sources. Differences among the Pacific coast populations indicated that some combination of phenotypic plasticity and genetic adaptation has occurred since the transplants in the 1870s. Microchemical analysis of otoliths from returning adults demonstrated an immature, extended freshwater life history form, locally known as “mini-shad”. These fish remain in the river for at least 1 year or enter salt water briefly and then return to fresh water for several months prior to subsequent seaward migration and return as adults. This and other forms of variation (extent of estuary use and size at sea water entry) expand the understanding of Alosine migration and life history diversity.

Evidence of successful hatching by introduced Red-eared Slider (<i>Trachemys scripta elegans</i>) in British Columbia, Canada

Globally, competition and disease from introduced Red-eared Slider (Trachemys scripta elegans) is a threat to co-existing native turtles. Red-eared Slider has been introduced throughout south coastal British Columbia (BC), mainly as pet turtle releases. Urban centres receive the most individuals, particularly in the Lower Mainland area outlying Vancouver, on southern Vancouver Island, and on the Sunshine Coast. The range of Red-eared Sliders in BC overlaps that of the Threatened Pacific Coast population of Western Painted Turtle (Chrysemys picta bellii). Herein we report on a survey for both species, noting presence, assessed population sizes, and nesting activity. Across 19 sites in the south coast occupied by both turtle species, we found the median abundance of Red-eared Sliders to be 2.5 times larger than that of Western Painted Turtles (Mann–Whitney U = 104, n1 = n2 = 19, Z-Score = −2.2188, P = 0.02642, two-tailed). There had been no evidence of Red-eared Sliders successfully hatching in the wild in BC until our study. We observed complete development, with 19 neonates from three different nesting sites between 2015 and 2017. Thus, Red-eared Slider is indeed established and able to breed in BC and thus competition and disease introduction from the species likely contributes to the decline of the Pacific Coast population of Western Painted Turtle, particularly at sites with low painted turtle numbers. The scale and mechanisms of impact requires further investigation.

Factors influencing the abundance of wintering western snowy plovers at Crown Memorial State Beach

Survival during the nonbreeding season, when mortality from food shortages and raptor predation is highest, influences shorebird population growth. These selection pressures, as well as anthropogenic influences, can shape wintering shorebird habitat use patterns. The western snowy plover (Charadrius alexandrinus nivosus) is a small shorebird that uses sand-spits, dune-backed beaches, open areas around estuaries for foraging and roosting. The Pacific Coast population of western snowy plovers is listed as a federally threatened species and a California Species of Special Concern. Previous studies suggest humans, dogs and corvids are sources of disturbance to plovers on public beaches. During 2014 to 2019, these disturbance factors were examined at Robert W. Crown Memorial State Beach in Alameda, California. In decreasing order of impact, the beach using public, corvids, and dogs were found to be the major stressors to over wintering plovers. Both the public and corvids respectively, resulted in disturbance and avoidance behaviors by plovers nearly 40% of the time. In 2015, the District created the Plover Protection Zone (PPZ) by installing symbolic fencing, signage, and establishing a volunteer team to monitor plovers and educate the public. In 2016, the potential prey abundance within the plover protection zone and areas directly north and south were examined using core samples and sticky traps. Statistical analysis showed a significant difference in the amount of macro-invertebrate prey available in the area used by the plovers as compared to other locations. Habitat choice and prey availability are vital to wintering shorebird. During this study, the wintering population of western snowy plovers increased from six to over 54 individuals.

A morphological, phylogenetic and phylogeographic reappraisal of the land crabs Gecarcinus quadratus De Saussure, 1853, and G. lateralis Fréminville in Guérin, 1832 (Decapoda: Gecarcinidae). Are they different species?

Land crabs of the genus Gecarcinus are distributed along both versants of the American continent. At some point four species were recognized: G. lateralis, G. nobilii, G. quadratus, and G. ruricola. Taxonomically, several authors have tried to differentiate Gecarcinus lateralis from the Atlantic coast and G. quadratus from the Pacific coast. Because morphologic characters used showed high intra-population variability, identification were very difficult. Consequently, these two species have occasionally been considered synonyms. To establish the degree of genetic difference between them a molecular analysis was performed with both species, G. lateralis and G. quadratus, including Mexican Pacific and Atlantic specimens, using the mitochondrial COI and 16S genes. The maximum clade credibility and maximum likelihood trees showed two clades with high support values, one corresponding to the Gulf of Mexico population and the other one to the Pacific coast population, with a genetic distance of 6.1%. The within-clade average distance for the Atlantic populations (G. lateralis) was 1.1% and 0.2% for those of the Pacific coast (G. quadratus). This supports the status of G. quadratus as a valid species, not as a synonym of G. lateralis. The estimated time of divergence between both species ranged between 2.3 to 4.3 million years, coinciding with the proposed closure of the Isthmus of Panama. Morphologically, some populations show high variability in somatic characters, whereas sexual appendices of males of both species showed very little variation. Color in life, shape of sternite 3, and shape and degree of coverage of the abdomen of thoracic sternites, in both sexes, are traits that can be used to differentiate both species.

Diminished warming tolerance and plasticity in low-latitude populations of a marine gastropod.

Models of species response to climate change often assume that physiological traits are invariant across populations. Neglecting potential intraspecific variation may overlook the possibility that some populations are more resilient or susceptible than others, creating inaccurate predictions of climate impacts. In addition, phenotypic plasticity can contribute to trait variation and may mediate sensitivity to climate. Quantifying such forms of intraspecific variation can improve our understanding of how climate can affect ecologically important species, such as invasive predators. Here, we quantified thermal performance (tolerance, acclimation capacity, developmental traits) across seven populations of the predatory marine snail (Urosalpinx cinerea) from native Atlantic and non-native Pacific coast populations in the USA. Using common garden experiments, we assessed the effects of source population and developmental acclimation on thermal tolerance and developmental traits of F1 snails. We then estimated climate sensitivity by calculating warming tolerance (thermal tolerance - habitat temperature), using field environmental data. We report that low-latitude populations had greater thermal tolerance than their high latitude counterparts. However, these same low-latitude populations exhibited decreased thermal tolerance when exposed to environmentally realistic higher acclimation temperatures. Low-latitude native populations had the greatest climate sensitivity (habitat temperatures near thermal limits). In contrast, invasive Pacific snails had the lowest climate sensitivity, suggesting that these populations are likely to persist and drive negative impacts on native biodiversity. Developmental rate significantly increased in embryos sourced from populations with greater habitat temperature but had variable effects on clutch size and hatching success. Thus, warming can produce widely divergent responses within the same species, resulting in enhanced impacts in the non-native range and extirpation in the native range. Broadly, our results highlight how intraspecific variation can alter management decisions, as this may clarify whether management efforts should be focused on many or only a few populations.

Assessing Accuracy of Sampling Schemes to Estimate Western Snowy Plover Reproductive Success

AbstractLike many wildlife species of management concern, the western snowy plover Charadrius nivosus nivosus is the subject of intensive population monitoring. However, intensive monitoring of reproductive success for this shorebird is time-consuming, financially costly, and potentially disruptive to the birds of interest. These constraints mean that intensive monitoring is not feasible throughout the range of the federally threatened Pacific Coast population. In this study, we used data collected from one intensively monitored subpopulation to assess how reductions in monitoring effort (number of chicks individually marked) would affect the accuracy of estimates of fledging success for western snowy plover chicks. We used monitoring data collected on chicks hatching at 1,845 nests from 2003 to 2012 as a theoretical subpopulation from which to draw random samples for this assessment. As expected, we found that accuracy (as measured by the inverse of percentage difference between sampled and actual fledge rates) increased with increasing percentage of the subpopulation monitored each year. We also found that the day of the week that chicks hatched and were banded had no effect on fledging success. Thus, reducing monitoring effort by banding chicks on specific days of the week is one suitable method for subpopulation sampling that has no embedded biases in the subsequent estimate of fledging success. The results of our analyses provide estimates of the accuracy of different sampling schemes, which should help managers of this threatened shorebird assess appropriate monitoring methods. We recommend use of our methods for others interested in assessing accuracy of sampling schemes for reproductive success of western snowy plover or other birds with similar life-history traits.

Fishes and invertebrates of oil and gas platforms off California: an introduction and summary

This paper serves as an introduction to a symposium on the role that California oil and gas platforms serve as habitats for fishes and invertebrates. As of 2019, there are 27 platforms in state and federal waters off California, and the decommissioning of some of these platforms is imminent. Thus, consideration of whether to completely remove a platform or cut it off at some depth below the sea surface and retain the submerged portion as a reef is a decision that will occur in the near future. The objectives of the 10 papers in this dedicated issue of the Bulletin of Marine Science are to: (1) increase scientific understanding of the inter- and intrarelationships of fish and invertebrate populations at offshore oil and gas platforms and natural reefs within the Southern California Bight; (2) determine the extent of influence of platform assemblages on southern California and the Pacific coast populations of fishes and invertebrates; and (3) synthesize relevant reports, existing peer-reviewed literature, and new data analyses into a single peer-reviewed reference. This introductory paper contains a synopsis of all extant California platforms including information on: (1) the original operator, (2) the current operator of records, (3) the date the platform was installed, (4) the first production date, (5) the platform's distance from shore [including whether it is state or outer continental shelf (OCS) waters], (6) the bottom depth of the platform, (7) the number of well slots, (8) the number of conductors, (9) what the platform produces (oil and/or gas), (10) the platform jacket dimensions [generally at the seafloor (bottom)], (11) the platform's footprint, (12) the midwater surface area, (13) the total removal weight, (14) the platform location, (15) the shell mound size, (16) the shell mound volume, (17) the shell mound height, (18) the center of the shell mound location, and (19) the bottom slope. In addition, we present an overview of all previous research on the biology and ecology of California platform organisms.

Deep divergence of Red-crowned Ant Tanager (Habia rubica: Cardinalidae), a multilocus phylogenetic analysis with emphasis in Mesoamerica.

Many neotropical species have a complex history of diversification as a result of the influence of geographical, ecological, climatic, and geological factors that determine the distribution of populations within a lineage. Phylogeography identifies such populations, determines their geographic distributions, and quantifies the degree of genetic divergence. In this work we explored the genetic structure of Habia rubica populations, a polytypic taxon with 17 subspecies described, in order to obtain hypotheses about their evolutionary history and processes of diversification. We undertook multilocus analyses using sequences of five molecular markers (ND2, ACOI-I9, MUSK, FGB-I5 and ODC), and sampling from across the species’ distribution range, an area encompassing from Central Mexico throughout much of South America. With these data, we obtained a robust phylogenetic hypothesis, a species delimitation analysis, and estimates of divergence times for these lineages. The phylogenetic hypothesis of concatenated molecular markers shows that H. rubica can be divided in three main clades: the first includes Mexican Pacific coast populations, the second is formed by population from east of Mexico to Panama and the third comprises the South American populations. Within these clades we recognize seven principal phylogroups whose limits have a clear correspondence with important geographical discontinuities including the Isthmus of Tehuantepec in southern Mexico, the Talamanca Cordillera, and the Isthmus of Panama in North America. In South America, we observed a marked separation of two phylogroups that include the populations that inhabit mesic forests in western and central South America (Amazon Forest) and those inhabiting the seasonal forest from the eastern and northern regions of the South America (Atlantic Forest). These areas are separated by an intervening dry vegetation “diagonal” (Chaco, Cerrado and Caatinga). The geographic and genetic structure of these phylogroups describes a history of diversification more active and complex in the northern distribution of this species, producing at least seven well-supported lineages that could be considered species.

External Auditory Exostoses and its Relationship to Prehistoric Abalone Harvesting on Santa Rosa Island, California

AbstractBioarchaeological research among prehistoric Pacific Coast populations has shown that external auditory exostoses (EAE) are found in high frequencies. On California's northern Channel Islands archaeological research has demonstrated that there was an intense exploitation of red abalone (Haliotis rufescens), particularly between ~8000 and 3500 years ago. If the Island Chumash were free‐diving for red abalone in subtidal waters, EAE should be prevalent in prehistoric populations from Santa Rosa Island. We recorded the presence or absence, number, side and severity of EAE growths for 207 adult individuals from three time periods on Santa Rosa Island. Our results show that ~11% of the total population was affected, including 22.5% of males and ~3.4% of females. The incidence among females increases from 0% in the Early period, to 2.6% in the Middle period, and 6.8% in the Late period. Overall these are lower rates than those reported for other Channel Island and Pacific Coast sites. Given the relatively low percentage of Santa Rosa Islanders affected with EAE, red abalones may have been harvested primarily in shallow waters rather than the deeper subtidal zone. Our data suggest that gender differences in food procurement activities existed on Santa Rosa Island throughout prehistory, congruent with the argument that EAE is an activity‐induced pathology that occurs with prolonged exposure to cold water and wind conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Evaluating the ecological and behavioural factors influencing Snowy PloverCharadrius nivosusegg hatching and the potential benefits of predator exclosures

SummaryAn understanding of the ecological factors influencing nest success and the effectiveness of management activities focused on improving nest success can be critical to successful conservation strategies for rare or declining species. Over seven breeding seasons (2006–2012) we examined the influence of nest spacing and habitat characteristics on hatching success for the nationally threatened Pacific coast population of the Snowy PloverCharadrius nivosusin coastal Washington, USA in two study areas. Specifically, we assessed the influence of clutch age, nesting season date, distance to conspecific nests, perpendicular distance to the high-tide (wrack) line, vegetation cover and other habitat characteristics at three spatial scales (1m2, 5m2, and 25 m2) centred on the nest. We also assessed the effectiveness of wire mesh cages placed around nests to exclude mammalian and avian nest-predators. We discovered and monitored 307 nests, placed predator exclosures around 142 of these nests and measured habitat variables at 251. Our selected base model included site and quadratic function of season-date. For the analysis examining habitat effects on nest success, only models with distance to nearest active nest ranked higher than the baseline model even when removing the nests that were very distant from conspecific nests (outliers). For these unexclosed nests, predation was the primary source of nest failure and crows and ravens were apparently the primary nest predators. Predator exclosures had a clear positive influence on nest survival. Even though we observed a positive exclosure effect, we recommend that they be used cautiously because we and others have observed adult mortality associated with exclosures. Regardless of the spatial scale, Snowy Plovers are primarily using nest sites with little vegetation, shell or woody material cover suggesting the need for large expanses of very sparsely or unvegetated habitats that allow birds to nest semi-colonially (with near neighbours).

Predator exclosures, predator removal, and habitat improvement increase nest success of Snowy Plovers in Oregon, USA

Management to increase reproductive success is commonly used to aid recovery of threatened and endangered species. The Western Snowy Plover (Charadrius nivosus nivosus) breeds from coastal Washington, USA, to Baja California, Mexico, and in disjunct interior sites. The Pacific coast population is federally listed as Threatened; habitat loss and nest loss to a suite of terrestrial and avian predators are thought to be primary factors limiting population growth in this species. In coastal Oregon, USA, a consortium of state and federal management agencies deployed nest exclosures on active Snowy Plover nests, initiated a lethal predator management program, and conducted local-scale habitat management in an effort to boost local productivity. During 1990–2009, we monitored 1,951 Snowy Plover nests at 9 sites with varying treatments. We examined the effectiveness of 3 types of nest exclosures (large, small, and outfitted with electric wire), predator removal, and habitat management on nest survival. Habitat management to remove invasive grasses and provide more suitable nesting substrate more than doubled nest survival. Predator management or use of any of the 3 types of exclosures also affected nest survival. There appeared to be no additional benefit to using both approaches, but the biological relevance of these findings is unclear because of site differences in treatments applied. Importantly, these management techniques only affected nesting success; their effect on other contributions to population viability (e.g., fledging success) was not correlated with nesting success. This long-term study illustrates the short-term benefits and tradeoffs of using nest exclosures, predator management, and habitat restoration to improve nesting success. Although we gained broader insight into the relative efficacy of common management techniques to improve avian nesting success, we cannot yet determine how improved nest success contributes to population growth.

Reevaluation of band‐tailed pigeon age classification criteria using wing attributes

ABSTRACTAge classification is important in understanding aspects of population productivity and dynamics, and making informed harvest management decisions. Since 1994 the U.S. Fish and Wildlife Service has, via the Parts Collection Survey, annually collected a wing from a sample of hunter‐harvested band‐tailed pigeons (Patagioenas fasciata) across the species' range in the United States to estimate productivity over time. Identification of age composition of the harvest depends on a key to quickly and accurately assign pigeons to age classes with as little as a wing from each pigeon. Existing keys for pigeon age classification do not incorporate more recent published information on timing and sequence of post‐juvenal molt. We developed a key in 1994 to classify age (juv, subad, ad) of band‐tailed pigeons from wings in North America based on earlier published keys (reported to be accurate 97.3%, on average) combined with information subsequently published on timing and sequence of post‐juvenal molt. Our key was applied and the examination procedure refined during our annual examining of pigeon wings for the Parts Collection Survey, 1994–2012. We examined all pigeon wings (1/bird) submitted to the Parts Collection Survey. The mean number of wings submitted annually was 494 (range = 114–1,090) from the Pacific Coast population and 79 (range = 3–265) from the Interior population. We examined wings during 1 day each year. Each wing was examined by an initial examiner and final examiner (C. E. Braun). We recorded discrepancies in age classification between examiners during 2005–2012. The mean annual number of discrepancies was 3.1 (SE = 0.3, range = 2–4, n = 8) representing a mean of 1.0% (SE = 0.2, range = 0.4–1.6%) of the total annual sample size. The key has been demonstrated to be accurate and transferable among biologists who have basic training in reading a key and examination of wings (primaries, secondaries, and coverts). Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Insights into phylogeny, sex function and age of Fragaria based on whole chloroplast genome sequencing

The cultivated strawberry is one of the youngest domesticated plants, developed in France in the 1700s from chance hybridization between two western hemisphere octoploid species. However, little is known about the evolution of the species that gave rise to this important fruit crop. Phylogenetic analysis of chloroplast genome sequences of 21 Fragaria species and subspecies resolves the western North American diploid F. vesca subsp. bracteata as sister to the clade of octoploid/decaploid species. No extant tetraploids or hexaploids are directly involved in the maternal ancestry of the octoploids.There is strong geographic segregation of chloroplast haplotypes in subsp. bracteata, and the gynodioecious Pacific Coast populations are implicated as both the maternal lineage and the source of male-sterility in the octoploid strawberries. Analysis of sexual system evolution in Fragaria provides evidence that the loss of male and female function can follow polyploidization, but does not seem to be associated with loss of self-incompatibility following genome doubling. Character-state mapping provided insight into sexual system evolution and its association with loss of self-incompatibility and genome doubling/merger. Fragaria attained its circumboreal and amphitropical distribution within the past one to four million years and the rise of the octoploid clade is dated at 0.372–2.05 million years ago.

Molecular phylogeography ofPteronotus davyi(Chiroptera: Mormoopidae) in Mexico

Pteronotus davyi, Davy's naked-backed bat, is a tropical bat whose current distribution in Mexico covers the watersheds of the Pacific and the Gulf coasts of Mexico, converges at the Isthmus of Tehuantepec, and continues into the Yucatan peninsula. We evaluated phylogeographic relationships among 18 populations in Mexico using data from the nucleotide sequence of the hypervariable II domain of the mitochondrial DNA control region from 105 specimens. Extant populations were distributed over 3 geographic regions (Pacific Coast, Gulf Coast, and Southeastern) that were delineated a priori according to floristic characteristics and biogeography. Coalescent simulations supported a phylogeographic model of 2 refugia situated in the south of Mexico (Arc and Soconusco refuges) during the late Pleistocene, followed by expansion into Pacific Coast, Gulf Coast, and Southeastern groups. The populations of the Southeast were genetically divergent from the Pacific and Gulf Coast populations, supporting the existence of 2 distinct lineages of P. davyi in Mexico, likely due to the Isthmus of Tehuantepec acting as a geographical barrier. Examination of our data revealed genetic differentiation of the Pacific and Gulf coastal groups but at a lower level relative to the Southeast. This pattern suggests that the Sierra Madre Occidental, Sierra Madre Oriental, and Sierra Madre del Sur act as physical barriers to dispersal for P. davyi.

Estimating Eastern Pacific Coast Populations of Whimbrels and Hudsonian Godwits, with an Emphasis on Chiloé Island, Chile

Abstract. A large proportion of the Hudsonian Godwits (Limosa haemastica) spending the boreal winter along the eastern Pacific Ocean coast are known to occur in the vicinity of Chiloe Island, Chile, but the importance of the region to Whimbrels (Numenius phaeopus) is less known. Ground counts conducted in 2007 and 2008 increased published estimates, at a minimum, of Pacific coast populations by 27% for Whimbrels (33,150 individuals) and 51% for Hudsonian Godwits (21,161 individuals). Bays and shorelines in the Chiloe Island region supported 99% of Hudsonian Godwits and, perhaps, 61% of Whimbrels estimated to occur along the Pacific coast during the boreal winter. Whereas Hudsonian Godwits aggregated in shallow bays on the eastern and northern coast of Chiloe Island, Whimbrels were more dispersed along the island's coastline and reached a density of 7.5 birds/km along sheltered gravel shorelines. Bays in the vicinity of Chiloe's capital, Castro, provided important foraging and roosting habitat for non-bree...

Geographic structure, genetic diversity and source tracking of Spartina alterniflora

AbstractAim To examine the distribution and structure of genetic variation among native Spartina alterniflora and to characterize the evolutionary mechanisms underlying the success of non‐native S. alterniflora.Location Intertidal marshes along the Atlantic, Gulf and Pacific coasts of North America.Methods amova, parsimony analysis, haplotype networks of chloroplast DNA (cpDNA) sequences, neighbour‐joining analysis, Bayesian analysis of population structure, and individual assignment testing were used.Results Low levels of gene flow and geographic patterns of genetic variation were found among native S. alterniflora from the Atlantic and Gulf coasts of North America. The distribution of cpDNA haplotypes indicates that Atlantic coast S. alterniflora are subdivided into ‘northern’ and ‘southern’ groups. Variation observed at microsatellite loci further suggests that mid‐Atlantic S. alterniflora are differentiated from S. alterniflora found in southern Atlantic and New England coastal marshes. Comparisons between native populations on the Atlantic and Gulf coasts and non‐native Pacific coast populations substantiate prior studies demonstrating reciprocal interspecific hybridization in San Francisco Bay. Our results corroborate historical evidence that S. alterniflora was introduced into Willapa Bay from multiple source populations. However, we found that some Willapa Bay S. alterniflora are genetically divergent from putative sources, probably as a result of admixture following secondary contact among previously allopatric native populations. We further recovered evidence in support of models suggesting that S. alterniflora has secondarily spread within Washington State, from Willapa Bay to Grays Harbor.Main conclusions Underlying genetic structure has often been cited as a factor contributing to ecological variation of native S. alterniflora. Patterns of genetic structure within native S. alterniflora may be the result of environmental differences among biogeographical provinces, of migration barriers, or of responses to historical conditions. Interactions among these factors, rather than one single factor, may best explain the distribution of genetic variation among native S. alterniflora. Comprehensive genetic comparisons of native and introduced populations can illustrate how biological invasions may result from dramatically different underlying factors – some of which might otherwise go unrecognized. Demonstrating that invasions can result from several independent or interacting mechanisms is important for improving risk assessment and future forecasting. Further research on S. alterniflora not only may clarify what forces structure native populations, but also may improve the management of non‐native populations by enabling post‐introduction genetic changes and the rapid evolution of life‐history traits to be more successfully exploited.

A rangewide population genetic study of trumpeter swans

For management purposes, the range of naturally occurring trumpeter swans (Cygnus buccinator) has been divided into two populations, the Pacific Coast Population (PP) and the Rocky Mountain Population (RMP). Little is known about the distribution of genetic variation across the species’ range despite increasing pressure to make difficult management decisions regarding the two populations and flocks within them. To address this issue, we used rapidly evolving genetic markers (mitochondrial DNA sequence and 17 nuclear microsatellite loci) to elucidate the underlying genetic structure of the species. Data from both markers revealed a significant difference between the PP and RMP with the Yukon Territory as a likely area of overlap. Additionally, we found that the two populations have somewhat similar levels of genetic diversity (PP is slightly higher) suggesting that the PP underwent a population bottleneck similar to a well-documented one in the RMP. Both genetic structure and diversity results reveal that the Tri-State flock, a suspected unique, non-migratory flock, is not genetically different from the Canadian flock of the RMP and need not be treated as a unique population from a genetic standpoint. Finally, trumpeter swans appear to have much lower mitochondrial DNA variability than other waterfowl studied thus far which may suggest a previous, species-wide bottleneck.

Evaluation of current population indices for band-tailed pigeons

There is no formal population survey specifically designed to index population abundance of band-tailed pigeons (Patagioenas fasciata) throughout their range. Data from the Breeding Bird Survey (BBS), Washington and Oregon Mineral-Site (WAORMS) surveys, and Washington Call Count (WACC) survey offer evidence of long-term population decline. We investigated the potential to augment BBS, WACC, and WAORMS surveys to provide more precise population indices for the Pacific Coast band-tailed pigeon (P. f. monilis) and augment the BBS to index the Interior or “Four Corners” population (P. f. fasciata). We calculated statistical power, the probability of detecting population change given that a change exists, and analyzed survey data to investigate the effect of route length, survey repetition, and sample size. Sample sizes of 50 sites or routes yielded corresponding powers of 99% for WAORMS, 54% for WACC, and 30% for Pacific BBS, to detect a 10% annual change over a 5-year period (a = 0.10). Route length and repetition of surveys had little impact on power. Mineral-site surveys provide the greatest potential to monitor breeding populations and detect short-term trends in the Pacific Coast population. New survey techniques are needed for the Interior band-tailed pigeon.

Geographic distribution and diversity in Claviceps purpurea from salt marsh habitats and characterization of Pacific coast populations

Claviceps purpurea specific to grasses in salt marsh habitats (Group G3) has previously been identified on Spartina spp. in two locations: New Jersey, USA and southern England. We have identified this subgroup of C. purpurea (G3) in 11 distinct populations including western Europe, South America, and along the Atlantic and Pacific Coasts of the USA. In addition, G3 C. purpurea was discovered on a new host grass genus, Distichlis. Unweighted pair group mean analyses of AFLP and RAPD data reveal distinct structure in G3 C. purpurea populations. Pacific coast populations show little diversity, suggesting they may have been introduced recently in that region. 43 isolates, representing 11 populations were identified as G3 based on the presence of an EcoRI restriction site in the 5.8S ribosomal DNA, and a clear genetic separation from isolates representing the other two C. purpurea subgroups (G1 and G2). In addition, all isolates originating from Spartina densiflora, S. foliosa, S. alterniflora, and S. anglica were identified as belonging to G3. RAPD and AFLP analyses supported the recognition of three discrete groups within C. purpurea and revealed high genetic variability between groups, with only 1.8% of polymorphic markers shared across all isolates. Similarly, analysis of molecular variation (AMOVA) revealed that genetic variability was mainly due to variations between groups (63.5%) rather than within groups (28.5%) or within populations (7.96%). G3 isolates were 35% similar, Pacific coast isolates 83% similar. Ninety percent similarity among isolates from the San Francisco Bay Area suggests this is a recently introduced population.

Age and Growth of Spotted Sand Bass, Paralabrax maculatofasciatus, in Bahia de Los Angeles, Baja California, Mexico, with Age Validation using Otolith Edge Analysis

Spotted sand bass, Paralabrax maculatofasciatus, were collected from Bahia de Los Angeles, Baja California, Mexico covering as wide a size range as possible over four seasons (spring, summer, fall, and winter). Age was estimated and growth parameters calculated from growth zones counted in transverse otolith sections. An otolith edge analysis indicated an opaque growth zone was deposited once per year during the summer, validating the annual periodicity. Spotted sand bass from this region are fast growing with a relatively short life span of up to 11 years. Growth differs from the disjunct Pacific coast population by having a higher growth rate and a shorter longevity.