scholarly journals Historical Connectivity and Demography of the Ferocious Reef Crab, Eriphia ferox (Crustacea; Eriphiidae), Demonstrate That Taoyuan Algal Reef Is an Essential Population Source Along the East Taiwan Strait

2022 ◽  
Vol 8 ◽  
Author(s):  
Mu-Han Chen ◽  
Ya-Yi Huang ◽  
Bi-Ying Huang ◽  
Hernyi Justin Hsieh ◽  
Jen Nie Lee ◽  
...  
Keyword(s):  
Population Expansion ◽  
Taiwan Strait ◽  
Coralline Algae ◽  
Secondary Contact ◽  
Source Population ◽  
The South ◽  
Stepping Stone ◽  
Ecological Features ◽  
Algal Reef ◽  
Population Source

The east Taiwan Strait is largely fringed by sandy and muddy habitats. However, a massive algal reef made of crustose coralline algae has been found along the coast off Taoyuan city in northwestern Taiwan. The porous structure of Taoyuan Algal Reef harbors high abundance and diversity in marine organisms, including the ferocious reef crab, Eriphia ferox. Such a pivotal geographic location and unique ecological features make Taoyuan Algal Reef a potential stepping stone connecting biotic reefs in the east Taiwan Strait, South China Sea to the south, and even the high latitude of Japan to the north. In this study, we examined the population connectivity and historical demography of E. ferox by analyzing mitochondrial cytochrome oxidase I (COI) fragments of 317 individuals sampled from 21 localities in the northwestern Pacific. Our analyses of haplotype network and pairwise FST comparisons revealed a lack of phylogeographical structure among E. ferox populations, implying the existence of a migration corridor connecting the South and East China Seas through the east Taiwan Strait. Multiple lines of evidence, including significant values in neutrality tests, unimodally shaped mismatch distributions, and Bayesian skyline plots elucidated the rapid population growth of E. ferox following the sea-level rise after Last Glacial Maximum (ca. 2–10 Ka). Such demographic expansion in E. ferox coincided with the time when Taoyuan Algal Reef started to build up around 7,500 years ago. Coalescent migration analyses further indicated that the large and continuous E. ferox population exclusively found in Datan Algal Reef, the heart of Taoyuan Algal Reef, was a source population exporting migrants both northward and southward to the adjacent populations. The bidirectional gene flow should be attributed to larval dispersal by ocean currents and secondary contact due to historical population expansion. Instead of serving as a stepping stone, our results support that Taoyuan Algal Reef is an essential population source for biotic reef-associated species along the east Taiwan Strait, and highlight the importance of conserving such a unique ecosystem currently threatened by anthropogenic development.

scholarly journals Population genomics of the emerging forest pathogen Neonectria neomacrospora

2020 ◽  
Author(s):  
Knud Nor Nielsen ◽  
Shyam Gopalakrishnan ◽  
Thorfinn Sand Korneliussen ◽  
Mikkel Skovrind ◽  
Kimmo Sirén ◽  
...  
Keyword(s):  
Population Genomics ◽  
Population Expansion ◽  
European Population ◽  
Ice Age ◽  
Source Population ◽  
Forest Pathogen ◽  
Comprehensive Collection ◽  
American Source ◽  
Last Ice Age ◽  
Ornamental Trees

ABSTRACTThe fungal pathogen Neonectria neomacrospora is of increasing concern in Europe where, within the last decade, it has caused substantial damage to forest stands and ornamental trees of the genus Abies (Mill.). Using whole-genome sequencing of a comprehensive collection of isolates, we show the extent of three major clades within N. neomacrospora, which most likely diverged around the end of the last Ice Age. We find it likely that the current European epidemic of N. neomacrospora was founded from a population belonging to the east North American clade. All European isolates (1957-2019) had a common evolutionary history, but substantial and asymmetrical gene flow from the larger American source population could be detected. The European population shows multiple signs of having gone through a bottleneck and subsequent population expansion.

scholarly journals Structure and Composition of Micro-Manganese Nodules in Deep-Sea Carbonate from the Zhaoshu Plateau, North of the South China Sea

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1016
Author(s):  
Hengchao Xu ◽  
Xiaotong Peng ◽  
Kaiwen Ta ◽  
Taoran Song ◽  
Mengran Du ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Deep Sea ◽  
Carbonate Rocks ◽  
The South China Sea ◽  
Coralline Algae ◽  
Manganese Nodules ◽  
The South ◽  
Raman Spectrometry ◽  
China Sea

The occurrence of deep-sea ferromanganese nodules and crusts on the seafloor is widespread, providing an important resource for numerous metals such as Ni, Co, and Cu. Although they have been intensively studied in the past, the formation of micro-manganese nodules within carbonate rocks has received less attention, despite the considerable amounts of manganese released from the dissolution of the calcareous framework. The micro-petrographic and geochemical characteristics of reef carbonate rocks recovered from the Zhaoshu plateau in the Xisha uplift, north of the South China Sea, were studied using optical microscopy, scanning electron microscopy, confocal Raman spectrometry, and an electron probe micro-analyzer. The carbonate rocks are composed of biogenic debris, including frameworks of coralline algae and chambers of foraminifer, both of which are suffering strong micritization. Within the calcite micrite, numerous micro-manganese nodules were identified with laminated patterns. Mineral and elemental evidence showed that the Mn oxides in the carbonates are mixed with 10 Å vernadite, 7 Å vernadite and todorokite, both of which are closely associated with the carbonate matrix. The micro-nodules were found to have high Mn/Fe ratios, enriched in Ni and Cu and depleted in Co. We infer that theses nodules are mixed type with early diagenetic growth under oxic–suboxic conditions. The re-distribution of manganite within the rocks is likely influenced by micritization of the calcareous framework. We deduce that microbial-associated reduction of manganite induces the formation of diagenetic todorokite similar to nodules buried in marine sediments.

The ecological impact of the sea urchin Paracentrotus lividus (Lamarck) in Lough Ine, Ireland

1983 ◽  
Vol 300 (1101) ◽  
pp. 513-552 ◽  
Keyword(s):  
Sea Urchin ◽  
Animal Species ◽  
Paracentrotus Lividus ◽  
Coralline Algae ◽  
Diurnal Fluctuation ◽  
Tide Pool ◽  
Crustose Coralline Algae ◽  
The South ◽  
South Basin ◽  
The North

An ecological account is given of the rocky shallow sublittoral of Lough Ine, County Cork, Republic of Ireland, from low water level to about 1 m below this level. With increasing distance from the Rapids mouth a forest of laminarian algae gives way to low algal bush, and still further into the lough the sea urchin Paracentrotus lividus destroys all soft upstanding algae. Much of the grazed area becomes overgrown by crustose coralline algae. Patches of the green algae Codium fragile ssp. tomentosoides and Enteromorpha clathrata fringe the Paracentrotus graze patches. An account is given of the effects of Paracentrotus on the shallow sublittoral community. Algae in the ungrazed areas accommodate large numbers of individuals and many species of invertebrates, especially amphipods, small gastropods and small polychaetes. In grazing, Paracentrotus destroys this population and its habitat. However, the removal of these algae, and of the sediment that they trap, provides a new habitat, suitable for plant and animal species that can resist Paracentrotus . Crustose coralline algae cover much of the rock, and are burrowed into or enclose the tubes of a characteristic and entirely different polychaete fauna. On the surface of the rocks are found saddle oysters ( Anomia ephippium ), limpets ( Patella aspera ) and other hard- shelled animal species. The relations between Codium and Paracentrotus have been investigated by transfer experiments in the ‘field’ and by observations with an aquarium tank. Paracentrotus readily eats Codium , especially when the urchins are at a high population density; but Codium benefits from the clearance of other algae, and is a quick recolonist, so that on balance it benefits from the presence of the urchin. Paracentrotus feeds mainly by day, and on a steep shore some wander up into the littoral region as the tide rises and destroy Fucus serratus . This accounts for the almost complete absence of F. serratus from the North Basin. Paracentrotus does not move upwards by night. The hard-shelled animal species Anomia, Patella, Chlamys varia , adult Gibbula cineraria and Pomatoceros , found plentifully on graze patches in the North Basin, diminish in abundance southwards even within grazed areas, while the numbers of the starfish Marthasterias glacialis under the rocks increase. Experiments show that Marthasterias readily eats Anomia . These Marthasterias are quite small. As they grow bigger they move away onto muddy areas and extend their diet to include large buried lamellibranchs. Small Paracentrotus are usually found in larger numbers underneath boulders than above, while larger ones tend to come up by day onto the tops, where they form graze patches. From a study of growth lines in the interambulacral plates and from growth in cages we conclude that a horizontal diameter of 30-40 mm (with considerable variation) is reached in 3-4 years from settlement. The peak in numbers of Paracentrotus visible in the South Basin in 1979 might perhaps be ascribed to a good settlement in the warm summers of 1975 and 1976. Temperature of the shallow marginal water of the lough is subject to diurnal fluctuation, as in a tide pool, and can reach high levels in summer. This might favour Paracentrotus . However, numbers of Paracentrotus are probably severely reduced by predators in the South Basin. Crabs have already been implicated. It is possible that the small or half grown Marthasterias under shallow sublittoral rocks might destroy newly settled Paracentrotus , although this still has to be demonstrated.

scholarly journals Parental population range expansion before secondary contact promotes heterosis

2020 ◽  
Author(s):  
Ailene MacPherson ◽  
Silu Wang ◽  
Ryo Yamaguchi ◽  
Loren H. Riesesberg ◽  
Sarah P. Otto
Keyword(s):  
Reproductive Isolation ◽  
Range Expansion ◽  
Genomic Analysis ◽  
Population Expansion ◽  
Ancestral Population ◽  
Secondary Contact ◽  
Hybrid Zones ◽  
Deleterious Alleles ◽  
Genomic Divergence ◽  
Slightly Deleterious Mutations

AbstractPopulation genomic analysis of hybrid zones is instrumental to our understanding of the evolution of reproductive isolation. Many temperate hybrid zones are formed by the secondary contact between two parental populations that had undergone post-glacial range expansion. Here we show that explicitly accounting for historical parental isolation followed by range expansion prior to secondary contact is fundamental for explaining genetic and fitness patterns in these hybrid zones. Specifically, ancestral population expansion can result in allele surfing, neutral or slightly deleterious mutations drift high frequency at the front of the expansion. If these surfed deleterious alleles are recessive, they can contribute to substantial heterosis in hybrids produced at secondary contact, counteracting negative-epistatic interactions between BDMI loci and hence can deteriorate reproductive isolation. Similarly, surfing at neutral loci can alter the expected pattern of population ancestry and suggests that accounting for historical population expansion is necessary to develop accurate null genomic models in secondary-contact hybrid zones. Furthermore, this process should be incorporated in macroevolutionary models of divergence as well, since such heterosis facilitated by parental-range expansion could dampen genomic divergence established in the past.

Molecular Diversity, Haplotype Distribution and Gene Flow of Bipolaris Sorokiniana Fungus Causing Spot Blotch Disease in Different Wheat Growing Zones

2021 ◽  
Author(s):  
Prem Lal Kashyap ◽  
sudheer Kumar ◽  
Anju Sharma ◽  
Ravi Shekhar Kumar ◽  
Sunita Mahapatra ◽  
...  
Keyword(s):  
Gene Flow ◽  
Balancing Selection ◽  
Population Expansion ◽  
Bipolaris Sorokiniana ◽  
Spot Blotch ◽  
Moderate Level ◽  
Common Source ◽  
Source Population ◽  
Internal Transcribed Spacer Region ◽  
Haplotypic Diversity

Abstract Bipolaris sorokiniana (BS) is an economically important fungal pathogen causing spot blotch of wheat (Trtiticum aestivum) and found in all wheat growing zones of India. Very scanty and fragmentary information is available on its genetic diversity. The current research is the first detailed report on the geographic distribution and evolution of BS population in five geographically distinct wheat growing zones [North Western Plain Zone (NWPZ), North Eastern Plain zone (NEPZ); North Hill Zone (NHZ), Southern Hill Zone (SHZ) and Peninsular Zone (PZ)] of India, studied by performing nucleotide sequence comparison of internal transcribed spacer region of 183 isolates. A moderate to high levels of haplotypic diversity was noticed in different wheat growing zones. Phylogenetic analysis suggests that B. sorokiniana exist in two distinct lineages as all isolates under study were grouped in two different clades and found analogous to the findings of haplotypic and median joining network analysis. The genetic parameters revealed the existence of 59 haplotypes with three major haplotypes (H_2, H_3, and H_25) which showed star-like structure network surrounded by several single haplotypes, revealing high frequency of the mutations ((Eta = 2 – 437) in total analyzed population. H_3 was observed as a predominant haplotype and prevalent in all the five zones. Moderate level of genetic differentiation was found between NEPZ and PZ (Fst = 0.563), whereas it was low between NEPZ and NHZ (Fst = -0.062). High level of gene flow was noticed between NWPZ and NEPZ (Nm = 14.32), while it was found minimum between SZ and NHZ (Nm = 0.50). Moreover, negative score of neutrality statistics (Tajima’s D and Fu’s FS test) for NWPZ, PZ and SHZ populations, suggested recent population expansion in these zones. However, positive score for both the neutrality tests observed in NEPZ and NHZ indicated the dominance of balancing selection in structuring their population. Recombination events were observed in the NWPZ, NEPZ and NHZ population, while it was absent in SHZ and PZ population. Thus, the lack of any specific genetic population structure in all the zones indicates for the expansion history only from one common source population i.e. NWPZ, a mega zone of wheat production in India. Overall, it seems that the predominance of individual haplotypes with a moderate level of genetic variation and men mediated movement of contaminated seed and dispersal of inoculum, mutations and recombination as prime evolutionary processes play essential role in defining the genetic structure of BS population.

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