Genetic structure of yellow cedar (Chamaecyparis nootkatensis)

2001 ◽  
Vol 79 (7) ◽  
pp. 822-828 ◽  
Author(s):  
Carol Ritland ◽  
Terry Pape ◽  
Kermit Ritland
Keyword(s):  
Genetic Structure ◽  
Gene Diversity ◽  
Species Conservation ◽  
Ice Age ◽  
North Coast ◽  
Evolutionary Divergence ◽  
Southeast Alaska ◽  
Chamaecyparis Nootkatensis ◽  
Inbreeding Coefficients ◽  
Age Range

A range-wide survey of isozyme variation in yellow cedar (Chamaecyparis nootkatensis (D. Don) Spach; or Alaska cedar) found significant inbreeding and a striking geographical structure. The proportion of diversity among populations (GST) was 0.139, and three major geographical groups were evident: (1) Vancouver Island - mid-north coast British Columbia (B.C.); (2) south coast B.C. - Washington state; (3) southeast Alaska. This may indicate the presence of multiple refugia during ice-age range contractions. Geographically disjunct populations in Oregon and southeastern B.C. were also genetically distinct. Adult inbreeding coefficients (F) were usually positive but varied widely among populations, as did gene diversity. The overall average of F = 0.18 suggests that considerable selfing (ca. 30%) occurs in this species. Other statistics were more typical for a conifer: within population heterozygosity (HS) averaged 0.148, total gene diversity (HT) was 0.171, and the number of alleles per locus and percentage polymorphic loci averaged 1.68 and 50, respectively. This geographic structure has implications for species conservation and for breeding programs. Also, previous studies of other Cupressoideae (Rich. ex Sweet) species indicate that these levels of inbreeding and population structure are not uncommon, and may influence evolutionary divergence in the Cupressoideae.Key words: Chamaecyparis nootkatensis, yellow cedar, genetic structure, inbreeding, phylogeography, isozymes.

scholarly journals Genetic Structure of Rhynchosporium secalis in Australia

1999 ◽  
Vol 89 (8) ◽  
pp. 639-645 ◽  
Author(s):  
B. A. McDonald ◽  
J. Zhan ◽  
J. J. Burdon
Keyword(s):  
Genetic Structure ◽  
Gene Diversity ◽  
Sampling Site ◽  
Geographic Distance ◽  
South Australia ◽  
Rflp Markers ◽  
Rhynchosporium Secalis ◽  
Fungal Isolates ◽  
Fungal Populations ◽  
Average Gene

Restriction fragment length polymorphism (RFLP) markers were used to determine the genetic structure of Australian field populations of the barley scald pathogen Rhynchosporium secalis. Fungal isolates were collected by hierarchical sampling from five naturally infected barley fields in different geographic locations during a single growing season. Genetic variation was high in Australian R. secalis populations. Among the 265 fungal isolates analyzed, 214 distinct genotypes were identified. Average genotype diversity within a field population was 65% of its theoretical maximum. Nei's average gene diversity across seven RFLP loci was 0.54. The majority (76%) of gene diversity was distributed within sampling site areas measuring ≈1 m2; 19% of gene diversity was distributed among sampling sites within fields; and 5% of gene diversity was distributed among fields. Fungal populations from different locations differed significantly both in allele frequencies and genotype diversities. The degree of genetic differentiation was significantly correlated with geographic distance between populations. Our results suggest that the R. secalis population in Western Australia has a different genetic structure than populations in Victoria and South Australia.

Distribution patterns of disjunct and endemic vascular plants in the interior wetbelt of northwest North AmericaThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.

Botany ◽  
2010 ◽  
Vol 88 (4) ◽  
pp. 409-428 ◽  
Author(s):  
Curtis R. Björk
Keyword(s):  
Vascular Plants ◽  
Distribution Patterns ◽  
South Coast ◽  
Ice Age ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
North Coast ◽  
The Pacific ◽  
Inland Northwest ◽  
Wet Climate

A region of contrastively wetter and milder climate occurs in inland northwest North America, separated from similar climates of the Pacific coast by 200–400 km. Researchers have long noted that numerous vascular plants divide their ranges between the interior wetbelt and coastal regions, although many such disjunctions have hitherto gone undocumented. Here I summarize all vascular plants shared between coastal and interior wetbelt regions, disjunct by at least 200 km. These disjunct taxa are assigned to north-coast and south-coast lists according to whether the coastal portions of the ranges occur primarily north or south of the southern limits of maximum continental glaciation. A list of interior wetbelt endemic taxa is also presented, focusing on those that occur at forested elevations. Presence/absence for coastal disjunct and endemic taxa were assigned to grid of 1° × 1° latitude–longitude cells. Using this grid, concentrations of disjunct and endemic taxa were detected, and total values per cell were tested in linear regression for a relationship to mean annual precipitation. In total, 116 coastal disjunct taxa were detected, 31 of them north-coastal and 85 south-coastal. Interior wetbelt endemic and subendemic taxa total 95, and of these, 46 were found primarily at forested elevations. North-coast taxa were found over a wide latitudinal range both north and south of the glacial limits, and their distribution had a weak positive relationship with annual precipitation. South-coast and endemic taxa were found mostly south of the glacial limits, and their distribution did not correlate to annual precipitation. The greatest concentrations of south coastal disjunct and endemic taxa occurred in the Clearwater region of north-central Idaho; a region noted by previous researchers to be a likely ice-age refugium for wet-climate dependent plants and animals. Inferences are made from these patterns, both for biogeographical understanding of the roles played by the interior wetbelt and some regions connecting to the coast, as well as for preservation of biodiversity and ecosystem continuity.

Chrysophyte microfossils record marked responses to recent environmental changes in high- and mid-arctic lakes

2001 ◽  
Vol 79 (6) ◽  
pp. 747-752 ◽  
Author(s):  
Alexander P Wolfe ◽  
Bianca B Perren
Keyword(s):  
Environmental Changes ◽  
Arctic Lakes ◽  
Ice Age ◽  
Algal Community ◽  
North Coast ◽  
Baffin Island ◽  
Lake Ecosystems ◽  
The North ◽  
Ecological Changes ◽  
Community Shifts

Rapid stratigraphic changes are recorded in recent assemblages of subfossil Chrysophyceae from the sediments of two highly contrasted arctic lakes, one situated in the polar desert of west-central Ellesmere Island, and the other on eastern Baffin Island in the mid-Arctic climatic zone. In Sawtooth Lake on the Fosheim Peninsula, concentrations of chrysophycean stomatocysts increase dramatically in sediments deposited since AD 1920. Only trace abundances of stomatocysts are encountered in older sediments. In Kekerturnak Lake, on the north coast of Cumberland Peninsula, scales of Mallomonas spp., previously absent from the sediment record, appear suddenly in the upper 5.5 cm of sediment and subsequently become ubiquitous in the top 1.0 cm. These results corroborate diatom stratigraphic data from other sites in the Canadian Arctic Archipelago, together suggesting that unprecedented ecological changes are presently occurring across this vast region. In all likelihood, these abrupt algal community shifts reflect the response of arctic lake ecosystems to well-documented climate warming since the Little Ice Age, with the implications that recent rates of environmental change are unprecedented in the context of the Holocene.Key words: Paleolimnology, arctic lakes, Chrysophyceae, stomatocysts, Mallomonas.

scholarly journals Persistence of single species of symbionts across multiple closely-related host species

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jorge Doña ◽  
Carolina Osuna-Mascaró ◽  
Kevin P. Johnson ◽  
David Serrano ◽  
Raül Aymí ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Host Species ◽  
Population Genetic ◽  
Single Species ◽  
Mite Species ◽  
Evolutionary Divergence ◽  
Species Status ◽  
Limited Dispersal ◽  
Dispersal Events ◽  
Symbiont Species

AbstractSome symbiont species are highly host-specific, inhabiting only one or a very few host species, and typically have limited dispersal abilities. When they do occur on multiple host species, populations of such symbionts are expected to become genetically structured across these different host species, and this may eventually lead to new symbiont species over evolutionary timescales. However, a low number of dispersal events of symbionts between host species across time might be enough to prevent population structure and species divergence. Overall, processes of evolutionary divergence and the species status of most putative multi-host symbiont systems are yet to be investigated. Here, we used DNA metabarcoding data of 6,023 feather mites (a total of 2,225 OTU representative sequences) from 147 infracommunities (i.e., the assemblage consisting of all mites of different species collected from the same bird host individual) to investigate patterns of population genetic structure and species status of three different putative multi-host feather mite species Proctophyllodes macedo Vitzthum, 1922, Proctophyllodes motacillae Gaud, 1953, and Trouessartia jedliczkai (Zimmerman, 1894), each of which inhabits a variable number of different closely related wagtail host species (genus Motacilla). We show that mite populations from different host species represent a single species. This pattern was found in all the mite species, suggesting that each of these species is a multi-host species in which dispersal of mites among host species prevents species divergence. Also, we found evidence of limited evolutionary divergence manifested by a low but significant level of population genetic structure among symbiont populations inhabiting different host species. Our study agrees with previous studies showing a higher than expected colonization opportunities in host-specific symbionts. Indeed, our results support that these dispersal events would allow the persistence of multi-host species even in symbionts with limited dispersal capabilities, though additional factors such as the geographical structure of some bird populations may also play a role.

scholarly journals Diverging Genetic Structure of Coexisting Populations of the Black Storm-Petrel and the Least Storm-Petrel in the Gulf of California

2020 ◽  
Vol 13 ◽  
pp. 194008292094917
Author(s):  
Misael D. Mancilla-Morales ◽  
Santiago Romero-Fernández ◽  
Araceli Contreras-Rodríguez ◽  
José J. Flores-Martínez ◽  
Víctor Sánchez-Cordero ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Mate Selection ◽  
Gulf Of California ◽  
Population Genetic ◽  
Life Histories ◽  
Gene Diversity ◽  
Isolation By Distance ◽  
Storm Petrel

Estimations on the influence of evolutionary and ecological forces as drivers of population gene diversity and genetic structure have been performed on a growing number of colonial seabirds, but many remain poorly studied. In particular, the population genetic structure of storm-petrels (Hydrobatidae) has been evaluated in only a few of the 24 recognized species. We assessed the genetic diversity and population structure of the Black Storm-Petrel ( Hydrobates melania) and the Least Storm-Petrel ( Hydrobates microsoma) in the Gulf of California. The two species were selected because they are pelagic seabirds with comparable ecological traits and breeding grounds. Recent threats such as introduced species of predators and human disturbance have resulted in a decline of many insular vertebrate populations in this region and affected many different aspects of their life histories (ranging from reproductive success to mate selection), with a concomitant loss of genetic diversity. To elucidate to what extent the population genetic structure occurs in H. melania and H. microsoma, we used 719 base pairs from the mitochondrial cytochrome oxidase c subunit I gene. The evaluation of their molecular diversity, genetic structure, and gene flow were performed through diversity indices, analyses of molecular and spatial variance, and isolation by distance (IBD) across sampling sites, respectively. The population genetic structure (via AMOVA and SAMOVA) and isolation by distance (pairwise p-distances and FST/1– FST (using ΦST) were inferred for H. microsoma. However, for H. melania evidence was inconclusive. We discuss explanations leading to divergent population genetic structure signatures in these species, and the consequences for their conservation.

Phenotypic and genotypic signature of saponin chemical composition in Chinese wild soybean (Glycine soja): revealing genetic diversity, geographical variation and dispersal history of the species

2018 ◽  
Vol 69 (11) ◽  
pp. 1126
Author(s):  
Yuya Takahashi ◽  
Xiang-Hua Li ◽  
Chigen Tsukamoto ◽  
Ke-Jing Wang
Keyword(s):  
Genetic Diversity ◽  
Chemical Composition ◽  
Genetic Structure ◽  
Southern China ◽  
Glycine Soja ◽  
Wild Soybean ◽  
Ice Age ◽  
High Genetic Diversity ◽  
The North ◽  
Or Genes

Saponin chemical composition was phenotyped and genotyped, and saponin composition-based geographical genetic diversity and differentiation were evaluated in Chinese wild soybean (Glycine soja Sieb. & Zucc.). Thirty-two phenotypes and 34 genotypes were confirmed from 3805 wild soybean accessions. Eleven phenotypes (AaαK, AaαIK, AaαIJK, AaBcEαJ, AaBcαK, AbEαIJ, AbαK, AbαIK, AbαIJK, AbβHAb and Aβ0) were newly detected. Four genes had frequencies: Sg-1a 78.8% and Sg-1b 21.0% at the Sg-1 locus; Sg-4 30.7% and Sg-6e 13.7% at their respective loci. The north-eastern and southern populations showed high genetic diversity; the Northeast region contained more novel variants (AuAe, A0, A0Bc, αH, αI αJ, αK, and AbβHAb), and the southern populations contained high frequencies of the Sg-4 gene. Gene differentiation (Fst) analysis suggested that Sg-4 and four group-α saponin alleles or genes (Sg-6e, Sg-6h, Sg-6i, Sg-6j) were important factors influencing the genetic structure and differentiation in Chinese wild soybeans. Geographical differentiation was characterised mainly by latitudinal differences, with two primary groups (north and south) based on saponin genes. Chinese wild soybean accessions differed from Japanese and South Korean ones in genetic structure based on saponin composition, the latter two being likely to have spread from southern China in the glacial stages during the last Ice Age.

Parallel evolutionary divergence in Arctic char Salvelinus alpinus complex from Transbaikalia: variation in differentiation degree and segregation of genetic diversity among sympatric forms

2015 ◽  
Vol 72 (1) ◽  
pp. 96-115 ◽  
Author(s):  
Natalia V. Gordeeva ◽  
Sergey S. Alekseyev ◽  
Arkadii N. Matveev ◽  
Vitalii P. Samusenok
Keyword(s):  
Microsatellite Loci ◽  
Life Histories ◽  
Salvelinus Alpinus ◽  
Gene Diversity ◽  
Adaptive Divergence ◽  
Evolutionary Divergence ◽  
Gene Pools ◽  
Ancestral Gene ◽  
Complex Species ◽  
Sympatric Forms

Despite the growing recognition of an important role of ecological speciation in evolution, the mechanisms driving sympatric divergence within a single population are not fully understood. We documented a series of parallel divergence events and tried to assess general regularities of the diversification of the ancestral gene pool. For that we analysed variation at microsatellite loci in populations of a highly polymorphic complex species Salvelinus alpinus from 14 Transbaikalian lakes, 10 of them hosting two or three forms: dwarf, small, and large. Our results suggest sympatric or parapatric origin of forms in all 10 lakes (in one lake, two forms out of three). Gene diversity and allelic richness of form populations are positively correlated with lake size and negatively correlated with modal length of mature fish, so that the dwarf form typically has the highest, and the large form, the lowest indices of genetic variation. The latter effect might be caused by differences in life histories, thus reflecting adaptive divergence. Sympatric forms have differently segregated gene pools (FST = 0.030–0.497, RST = 0.011–0.440) and restricted (m = 0.002–0.042) typically asymmetric long-term gene flow. The level of reproductive isolation among forms assessed using putatively neutral microsatellite loci is correlated with their differentiation in morphology, including trophic-related gill raker number, and with lake depth (i.e., with segregation of diets and with habitat diversity), which corresponds to “isolation-by-adaptation” pattern. Our data suggest that the advance in speciation stage apparently more depends upon ecological opportunities of lake ecosystems than upon their age.

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