Degree Of Geographic Isolation Research Articles

Asynchronous life cycles contribute to reproductive isolation between two Alpine butterflies.

Geographic isolation often leads to the emergence of distinct genetic lineages that are at least partially reproductively isolated. Zones of secondary contact between such lineages are natural experiments that allow investigation of how reproductive isolation evolves and co-existence is maintained. While temporal isolation through allochrony has been suggested to promote reproductive isolation in sympatry, its potential for isolation upon secondary contact is far less understood. Sampling two contact zones of a pair of mainly allopatric Alpine butterflies over several years and taking advantage of museum samples, we show that the contact zones have remained geographically stable over several decades. Furthermore, they seem to be maintained by the asynchronous life cycles of the two butterflies, with one reaching adulthood primarily in even and the other primarily in odd years. Genomic inferences document that allochrony is leaky and that gene flow from allopatric sites scales with the degree of geographic isolation. Overall, we show that allochrony has the potential to contribute to the maintenance of secondary contact zones of lineages that diverged in allopatry.

The Mitochondrial landscape of the Konjuh and Majevica mountains of northeastern Bosnia: The view in the context genetic and demographic history

This study is the first report on the mtDNA profile of human settlements of the Konjuh and Majevica mountains of northeastern Bosnia. The aims of this study were: a) determination of mitochondrial genetic structure of populations of the Konjuh and Majevica mountains of northeastern Bosnia; b) detection of trace of ancient of mtDNA variations; and c) assessment of genetic relations with other Bosnian and Herzegovina populations and neighboring populations from the Balkan region. The genetic structure of populations of Konjuh and Majevica is shaped by western Eurasian maternal signals, which may trace their ancestry to the Paleolithic, pre-Neolithic and Neolithic. Especially interesting is the feature of the Neolithic expansion in this area. This applies especially to the presence of the pre-Neolithic lineages HV*and N1a in northeastern Bosnia, which can indicate an early settlement of this region of Bosnia by pre-Neolithic populations from the Middle East. This region abounds with resources of salt sites, which might suggest in favor of the thesis that the early-Neolithic colonists needed a safe source of salts so as to settle in the Balkan area. The populations of mountains of northeastern Bosnia indicate elements of the local population history, but they do not show strict genetic closure in relation to the neighboring populations of the Balkans. This may be a consequence of the population size, degree of geographic isolation and events of migration.

Spatial structure and dispersal dynamics in a house sparrow metapopulation.

The effects of spatial structure on metapopulation dynamics depend upon the interaction between local population dynamics and dispersal, and how this relationship is affected by the geographical isolation and spatial heterogeneity in habitat characteristics. Our aim is to examine how emigration and immigration of house sparrows Passer domesticus in a Norwegian archipelagic metapopulation are affected by key factors predicted by classic metapopulation models to affect dispersal-spatial and temporal variation in population size, inter-island distance, local demography and habitat characteristics. This metapopulation can be divided into two major habitat types: (a) islands closer to the mainland where sparrows breed in colonies on farms, and (b) islands without farms, situated farther away from the mainland where sparrows are exposed to harsher environmental conditions. Dispersal was spatially structured within the metapopulation; there was proportionally and numerically less emigration and immigration involving farm islands, as compared to non-farm islands. Furthermore, emigration and immigration occurred mostly between nearby islands. Moreover, emigration in response to spatial differences in mean population size differed between the habitat types, but populations with large mean received more immigrants in both habitat types. The number of emigrants and immigrants was negatively related to long-term recruit production, which was not the case in non-farm islands. The proportion and number of emigrants was positively related to temporal increases in recruit production on farm islands, however not on non-farm islands. Our results demonstrate that spatial heterogeneity in environmental conditions influences how spatial variation in long-term mean population size, and temporal and spatial variation in recruit production, affects dispersal dynamics. The spatial structure of this metapopulation is therefore best described by a spatially explicit model in which the exchange of individuals within each habitat type is strongly affected by the degree of geographical isolation, population size and recruit production. However, these relationships differed between the two habitat types; non-farm islands showing similarities to a mainland-island model type of structure, whereas farm islands showed features more associated with source-sink or balanced dispersal models. Such differential dispersal dynamics between habitat types are expected to have important consequences for the ecological and evolutionary dynamics within this metapopulation.

Population genetic and evolution analysis of controversial genus Edwardsiella by multilocus sequence typing

At present, the genus Edwardsiella compiles five species: E. tarda, E. hoshinae, E. ictaluri, E. piscicida and E. anguillarum. Some species of this genus such us E. ictaluri and E. piscicida are important pathogens of numerous fish species. With the description of the two latter species, the phylogeny of Edwardsiella became more complicated. With the aim to clarify the relationships among all species in the genus, a multilocus sequence typing (MLST) approach was developed and applied to characterize 56 isolates and 6 reference strains belonging to the five Edwardsiella species. Moreover, several analyses based on the MLST scheme were performed to investigate the evolution within the genus, as well as the influence of recombination and mutation in the speciation. Edwardsiella isolates presented a high genetic variability reflected in the fourteen sequence types (ST) represented by a single isolates out of eighteen total ST. Mutation events were considerably more frequent than recombination, although both approximately equal influenced the genetic diversification. However, the speciation among species occurred mostly by recombination. Edwardsiella genus displays a non-clonal population structure with some degree of geographical isolation followed by a population expansion of E. piscicida. A database from this study was created and hosted on pubmlst.org (http://pubmlst.org/edwardsiella/).

Interisland gene flow among populations of the buff‐banded rail (Aves: Rallidae) and its implications for insular endemism in Oceania

Studies of fragmented habitat, such as island archipelagos, provide insights into the microevolutionary processes that drive early stages of diversification. Here, we examined genetic variation and gene flow among populations of the widespread buff‐banded rail Gallirallus philippensis in Oceania to understand the factors that promote speciation associated within this bird lineage. We analysed mtDNA Control Region sequences and six microsatellite loci from a total of 152 individuals of buff‐banded rail on islands and continental areas. We used a phylogeographic model‐testing approach and a structured spatial design ranging from within to among archipelagoes in the south Pacific. Buff‐banded rail populations in the Philippines archipelago and nearby Palau and Wallacea had high genetic diversity while those in geographically distant Australia showed lower variation. Other archipelagos sampled were found to have less genetic diversity and included haplotypes closely related to Wallacea (Bismarck, Vanuatu, New Caledonia) or Australia (New Zealand, Samoa, Fiji, Cocos Islands). Nucleotide diversity and allele frequency declined with degree of geographic isolation but haplotype diversity remained more even. However, both nucleotide and haplotype diversities were positively correlated with land area. Microsatellite data for a subset of locations showed moderate to high genetic differentiation and significant pairwise FST despite a relatively high migration rate. Our results are mostly consistent with a model of abrupt genetic changes due to founder events with multiple dispersals into Australia from Wallacea and Bismarck. Australia has probably been the source of birds for islands in the Pacific. This is shown by decreasing genetic diversity and growing genetic differentiation when distances separating populations increased from Australia. A history of range expansion and divergent natural selection may help explain the existence of numerous sympatric Gallirallus island endemics.

Phylogeography of the Vermilion Flycatcher species complex: Multiple speciation events, shifts in migratory behavior, and an apparent extinction of a Galápagos-endemic bird species

The Vermilion Flycatcher (Pyrocephalus rubinus) is a widespread species found in North and South America and the Galápagos. Its 12 recognized subspecies vary in degree of geographic isolation, phenotypic distinctness, and migratory status. Some authors suggest that Galápagos subspecies nanus and dubius constitute one or more separate species. Observational reports of distinct differences in song also suggest separate species status for the austral migrant subspecies rubinus. To evaluate geographical patterns of diversification and taxonomic limits within this species complex, we carried out a molecular phylogenetic analysis encompassing 10 subspecies and three outgroup taxa using mitochondrial (ND2, Cyt b) and nuclear loci (ODC introns 6 through 7, FGB intron 5). We used samples of preserved tissues from museum collections as well as toe pad samples from museum skins. Galápagos and continental clades were recovered as sister groups, with initial divergence at ∼1mya. Within the continental clade, North and South American populations were sister groups. Three geographically distinct clades were recovered within South America. We detected no genetic differences between two broadly intergrading North American subspecies, mexicanus and flammeus, suggesting they should not be recognized as separate taxa. Four western South American subspecies were also indistinguishable on the basis of loci that we sampled, but occur in a region with patchy habitat, and may represent recently isolated populations. The austral migrant subspecies, rubinus, comprised a monophyletic mitochondrial clade and had many unique nuclear DNA alleles. In combination with its distinct song, exclusive song recognition behavior, different phenology, and an isolated breeding range, our data suggests that this taxon represents a separate species from other continental populations. Mitochondrial and nuclear genetic data, morphology, and behavior suggest that Galápagos forms should be elevated to two full species corresponding to the two currently recognized subspecies, nanus and dubius. The population of dubius is presumed to be extinct, and thus would represent the first documented extinction of a Galápagos-endemic bird species. Two strongly supported mitochondrial clades divide Galápagos subspecies nanus in a geographic pattern that conflicts with previous hypotheses that were based on plumage color. Several populations of nanus have recently become extinct or are in serious decline. Urgent conservation measures should seek to preserve the deep mitochondrial DNA diversity within nanus, and further work should explore whether additional forms should be recognized within nanus. Ancestral states analysis based on our phylogeny revealed that the most recent common ancestor of extant Vermilion Flycatcher populations was migratory, and that migratory behavior was lost more often than gained within Pyrocephalus and close relatives, as has been shown to be the case within Tyrannidae as a whole.

Application of Intersectional Analysis to Data on Domestic Violence Against Aboriginal Women Living in Remote Communities in the Province of Quebec

This article discusses the theoretical and analytical intersectionality approach, focusing on its application to an analysis of empirical data obtained from qualitative research into domestic violence against Aboriginal women living in four remote communities in Quebec. Nonprobability sampling was used to select and recruit 40 participants. Four focus groups took place, one in each of the participating communities. The qualitative data were subjected to a thematic content analysis emphasizing the feminist intersectionality perspective. The findings revealed the existence of different domination systems, as well as oppressive actions that interlock and interact at multiple and shifting levels, all of which shape and contribute to the reproduction of domestic violence among women living in remote Aboriginal communities. The intersectionality approach highlighted the important role played not only by race, gender, and social class, but also by the historical context and the degree of geographic isolation in the domestic violence experienced by Aboriginal women living in remote communities. All these social systems increase the vulnerability of Aboriginal women to domestic violence. This paper is one of the few scholarly attempts made so far to apply intersectional analysis to empirical data on the phenomenon of domestic violence as experienced by Aboriginal women.

Disentangling the Population Structure and Evolution of the Clam Pathogen Vibrio tapetis

Vibrio tapetis is a fastidious slow-growing microorganism that causes the Brown Ring Disease in clams. Recently, two subspecies for this bacterial pathogen have been proposed. We have developed a multilocus sequence typing scheme and performed evolutionary studies of V. tapetis population using the great majority of isolates of V. tapetis obtained worldwide until now (30 isolates). V. tapetis constitutes a high polymorphic population, showing low diversity indexes and some genetic discontinuity among the isolates. Mutation events are more frequent than recombination, although both are approximately equally important for genetic diversification. In fact, the divergence between subspecies occurred exclusively by mutation but the diversity observed among isolates of the same subspecies appeared to be generated mostly by recombination. Between the subspecies, genetic distance is very high and almost no recurrent gene flow exists. This pathogen displays a non-clonal population structure with an ancient spatial segregation population and some degree of geographical isolation, followed by a population expansion, at least for V. tapetis subsp. tapetis. A database from this study was created and hosted on publmlst.org ( http://pubmlst.org/vtapetis/ ).

Rapid Divergent Evolution of Male Genitalia Among Populations of Drosophila buzzatii

Fil: Soto, Ignacio Maria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Ecologia, Genetica y Evolucion de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecologia, Genetica y Evolucion de Buenos Aires; Argentina

Genetic analysis for geographic isolation comparison of brown bears living in the periphery of the Western Carpathians Mountains with bears living in other areas

Populations of the European brown bear (Ursus arctos L.) differ substantially in size, degree of geographic isolation and level of genetic diversity. Present patterns result from phylogeographic processes and profound human intervention. We assessed the genetic variability of a subpopulation of brown bears near the periphery of their range in the Western Carpathian Mountains and compared their genetic properties with those of bears in the core of the same population and elsewhere. Samples were collected non-invasively in 2007-2008 and 2010 in Stražovske Vrchy Protected Landscape Area (PLA) in Slovakia (included in the NATURA 2000 networking programme). Seven polymorphic microsatellite loci (UaMU26, UaMU64, G10B, G1D, G10L, UaMU50 and UaMU51) were amplified using a nested PCR in order to assess the following parameters: variability, allelic combinations, heterozygosity, number of alleles and inbreeding coefficient. Sufficient brown bear DNA for analysis was obtained from 57 out of 140 samples (41%), among which 45 different genotypes were identified. Loci had a mean of 2.71 ± 0.76 alleles. Average observed heterozygosity was 0.59. The inbreeding coefficient was negative for all but one of the analysed loci (2007-2008). In the year 2010 was negative three of seven loci. These results imply that gene flow with other parts of the population has been maintained in the reduced level and the isolation level of bears in the study area was not so low. Nevertheless, the genetic variability of bears in Stražovske Vrchy PLA was lower than that reported from other localities in the Carpathian Mountains. The results are discussed in the context of behavioural ecology and conservation genetics.

Opportunities for the development of tourism in Letea River levee of the Danube Delta biosphere reserve

At the level of the Delta rural areas dominate. The river levee is Letea – C. A. Rosetti locality and it is considered the most isolated settlement in Romania. Making a strategic tool for tourism development in the Rosetti locality from turning its entire natural and cultural heritage has proven to be a multi-step problem, given the economic and social context of human settlements. Lifetime socio-economic development depends on a minimum shipping and road access. The main problem is to change the management of existing resources and to reduce the phenomenon of accentuated depopulation and the current economic underdevelopment. There are many drawbacks, and the last 20 years have brought essential positive changes to the community life. The degree of geographical isolation does not need to be primordial and may diminish its influence by expanding and upgrading communication lines and standard of living by making facilities and utilities, by diversifying local occupations. There are real opportunities for investment to start work and develop rural tourism in this situation.

ISOLATION AND DEVELOPMENT

This paper exploits cross-country variation in the degree of geographical isolation, prior to the advent of sea-faring and airborne transportation technologies, to examine its impact on the course of economic development across the globe. The empirical investigation establishes that prehistoric geographical isolation has generated a persistent beneficial effect on the process of development and contributed to the contemporary variation in the standard of living across countries.

Isolation and Development

This paper exploits cross-country variation in the degree of geographical isolation, prior to the advent of seafaring and airborne transportation technologies, to examine its impact on the course of economic development across the globe. The empirical investigation establishes that prehistoric geographical isolation has generated a persistent beneficial effect on the process of development and contributed to the contemporary variation in the standard of living across countries.

Isolation and Development

This paper exploits cross-country variation in the degree of geographical isolation, prior to the advent of sea-faring and airborne transportation technologies, to examine its impact on the course of economic development across the globe. The empirical investigation establishes that prehistoric geographical isolation has generated a persistent beneficial effect on the process of development and contributed to the contemporary variation in the standard of living across countries.

Incrimination ofSimulium thyolense(Diptera: Simuliidae) as the anthropophilic blackfly in the Thyolo focus of human onchocerciasis in Malawi

The sibling species of the Simulium damnosum complex that are potential vectors in the foci of human onchocerciasis found in southern Malawi (the southern-most foci in Africa) were identified, using a combination of cytotaxonomic and molecular techniques. Simulium thyolense was found to be the most abundant species within the foci (representing 91% of the larvae collected), whilst S. kilibanum and cytoforms of the 'Ketaketa' subcomplex were the dominant members of the complex found outside of the foci. As all 188 biting female flies collected from the Thyolo, Mwanza and Mulanje foci were identified as S. thyolense, this species is probably the only significant vector of Onchocerca volvulus in the area, and the other Simulium species collected are assumed to be zoophilic. The results confirm the diagnostic value of the size of the amplicon(s) produced in PCR based on the sequences coding for the internal-transcribed-spacer region of the nuclear ribosomal DNA (ITS-1 rDNA), with a characteristic 340bp amplicon for S. thyolense. Chromosomal polymorphisms within S. thyolense indicate some degree of geographical isolation of the 'Thyolo-Mulanje' focus from the Mwanza focus.

Geographical Exclusion in Rural Areas of El Salvador: Its Impact on Labor Market Outcomes

The main objective of this study is to examine the impact of geographic isolation of individuals living in El Salvador's rural areas on three labor market outcomes: labor force participation decision, sector of employment, and labor income. In this study, it is hypothesized that living in geographic isolation has a negative impact on rural workers' labor outcomes. The main results of this study indicate that the degree of geographic isolation does not discourage men from working; on the contrary, men living farther away from urban and maquila jobs are more likely to work. However, women living in greater isolation are highly concentrated in own-production agricultural activities, where women's skills are rewarded less than comparable men's skills. Through concentration into this sector, women living in geographic isolation obtain worse labor outcomes than men. When working in own-account nonagricultural production, geographic isolation also has a negative impact on men's labor income.

Biogeographic Predictors of Genetic Diversity in Populations of Eastern African Chimpanzees ( Pan troglodytes schweinfurthi )

I collected mitochondrial DNA sequences—hypervariable region 1 of the control region—from 281 eastern chimpanzees in 19 geographically defined populations and calculated genetic diversity measures to test the hypothesis that populations inhabiting the reconstructed locations of Pleistocene forest refugia harbor higher genetic diversities than those of other populations. The hypothesis is only weakly supported. Population genetic diversity is not significantly correlated with geographic proximity to refugia, with the area of forest that the populations currently occupy, or with the degree of geographic isolation of the populations. However, the two populations displaying the consistently highest genetic diversities are located in refuge areas: Uganda's Rwenzori Mountains and the eastern Democratic Republic of Congo's Ituri Forest. These results, in combination with previously findings, imply that chimpanzees may have lived both in and out of refugia during periods when tropical forests were restricted to refugia. This interpretation is consistent with the notion of chimpanzees as an extraordinarily vagile species, capable of maintaining gene flow across habitat mosaics of forest, woodland, and savannah.

Species Richness of Mammals Inhabiting Nearshore Archipelagoes: Area, Isolation, and Immigration Filters

Patterns in community structure of non-volant mammals on islands of the Drummond Archipelago (northwestern Lake Huron) were compared to those of insular mammals in-habiting three other nearshore archipelagoes to test the hypothesis that species-area and species-isolation relationships are strongly influenced by the nature of the immigration filter. All four archipelagoes shared similar habitats and nearly identical species pools, but differed substantially in characteristics of their filters. Islands of the Drummond Archipelago tended to have more species per area and more species per degree of geographic isolation. The rate of decline in species richness with increasing isolation was similar and relatively low for islands of the Drummond Archipelago and central Lake Michigan. In comparison to these lacustrine archipelagoes, which had relatively weak filters (high immigration rates), mammalian species richness declined much more rapidly with isolation of islands along the coast of Maine and the St. Lawrence River, where strong currents and instability of ice-cover impede immigration. These insights may have special relevance for conservation of endangered species, many of which are restricted to ecosystems fragmented and isolated at a scale similar to that of nearshore archipelagoes.

DIFFERENT SPATIAL SCALES OF ADAPTATION IN THE CLIMBING BEHAVIOR OF PEROMYSCUS MANICULATUS: GEOGRAPHIC VARIATION, NATURAL SELECTION, AND GENE FLOW.

Patterns of geographic variation in tree-climbing ability of Peromyscus maniculatus were used to examine the influence of spatial variation in natural selection and gene flow on the genetic divergence of climbing behavior among populations. Offspring of adults of two subspecies sampled from 10 localities in montane conifer forest, conifer woodland, and desert scrub/grassland habitats were raised in the laboratory and tested to determine their tree-climbing ability (the maximum diameter artificial rod that a mouse could climb). Comparisons of mean rod-climbing scores revealed that individuals of P. m. rufinus sampled from montane conifer forest and conifer woodland in Arizona were better climbers than P. m. sonoriensis sampled from conifer woodland and desert habitats in Nevada. This result was consistent with the hypothesis that natural selection has produced large-scale adaptation in climbing behavior. However, the climbing ability of P. m. sonoriensis sampled from conifer woodland habitats on isolated mountaintops in Nevada has not evolved in response to natural selection to the degree expected. In addition, populations sampled from desert grassland habitat, adjacent to woodland P. m. rufinus in Arizona, have climbing abilities that are not significantly different from conifer woodland populations. These observations indicate that local adaptation was constrained. An estimate of the heritability of climbing ability (h2 = 0.352 ± 0.077) indicates that lack of a response to selection was not due to the absence of additive genetic variation. In addition, regressions of interpopulation differences on the degree of geographic isolation between pairs of populations do not support the hypothesis that gene flow between habitats has constrained evolution. Instead, a combination of historical events and insufficient time to respond to selection appears to have influenced geographic variation and the spatial scale of adaptation in climbing ability.

The application of electrophoresis to the systematics of the marine dinoflagellate genus Heterocapsa

Eight strains (and three subcultures of one strain) of four species of the marine dinoflagellate genus Heterocapsa ( H. illdefina, H. niei, H. pygmeea, and H. triquetra) were assayed electrophoretically for enzymes encoded by four loci. Additionally, electromorphs of the peridinin-chlorophyll a-protein pigment complex were investigated. A roote Wagner tree was constructed and indicates evolutionary lines of descent, as well as the degree of relatedness between subcultures, isolates, and taxa. There was a correlation between the degree of geographical isolation and taxonomic distance as determined from electrophoresis. Minor electrophoretic differences were detected among four subcultures of H. pygmaea that were prepared 25 years ago. The present morphologically derived classification of this genus agrees with our biochemically based systematic scheme with one exceptin. One of the isolates previously identified as H. pygmaea is considered an undescribed, possibly sibling species.