scholarly journals Phylogeography of Neomysis americana (Crustacea, Mysida), focusing on the St. Lawrence system

2019 ◽  
Vol 41 (5) ◽  
pp. 723-739
Author(s):  
GrÉgoire Cortial ◽  
Ryan Woodland ◽  
Rachel Lasley-Rasher ◽  
Gesche Winkler
Keyword(s):  
East Coast ◽  
Secondary Contact ◽  
Sampling Area ◽  
Lawrence Estuary ◽  
Key Species ◽  
Show Evidence ◽  
Cryptic Species Complex ◽  
St Lawrence Estuary ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract Species characterized by low dispersal capacities, such as mysids, usually show evidence of genetic differentiation. Many mysids are broadly distributed and often show eurythermal and euryhaline traits. This study aimed to describe intraspecific genetic structure and the phylogeography of Neomysis americana, a key species of estuarine food webs in northwest Atlantic, using the mitochondrial cytochrome c oxidase subunit I gene. We sampled 26 populations across the St. Lawrence system (SLS) and two along the east coast of North America [Penobscot and Chesapeake Bay (CB)]. Sequencing of 420 individuals revealed three divergent (>3%) lineages (LA, LB, LC) across the sampling area suggesting that N. americana represents a cryptic species complex. The distribution of the lineages was geographically structured. LC occurred in the CB only, whereas LA and LB co-occurred along the SLS and Penobscot Bay. This suggests secondary contact after the last glacial maximum. In the SLS the lineage LA dominated the estuarine transition zone and the Gulf of St. Lawrence, whereas the lineage LB was prevalent in the lower St. Lawrence Estuary, potentially due to different eco-physiological preferences. These results might help to define reasonable entities for research and management.

An Optical luminescence chronology for late Pleistocene aeolian activity in the Colombian and Venezuelan Llanos

2016 ◽  
Vol 85 (2) ◽  
pp. 299-312 ◽  
Author(s):  
Andrew S. Carr ◽  
Simon J. Armitage ◽  
Juan-Carlos Berrío ◽  
Bibiana A. Bilbao ◽  
Arnoud Boom
Keyword(s):  
Dry Season ◽  
Gallery Forest ◽  
Aeolian Activity ◽  
Show Evidence ◽  
The Mean ◽  
Venezuelan Llanos ◽  
Age Constraints ◽  
The Last Glacial Maximum ◽  
Osl Age ◽  
The Last Glacial

The lowland savannas (Llanos) of Colombia and Venezuela are covered by extensive aeolian landforms for which little chronological information exists. We present the first optically stimulated luminescence (OSL) age constraints for dunes in the Llanos Orientales of lowland Colombia and new ages for dunes in the Venezuelan Llanos. The sampled dunes are fully vegetated and show evidence of post-depositional erosion. Ages range from 4.5 ± 0.4 to 66 ± 4 ka, with the majority dating to 27–10 ka (Marine Isotope Stage 2). Some dunes accumulated quickly during the last glacial maximum, although most were active 16–10 ka. Accretion largely ceased after 10 ka. All dunes are elongated downwind from rivers, parallel with dry season winds, and are interpreted as source-bordering features. As they are presently isolated from fluvial sediments by gallery forest it is proposed that activity was associated with a more prolonged dry season, which restricted gallery forest, leading to greater sediment availability on river shorelines. Such variability in dry season duration was potentially mediated by the mean latitude of the ITCZ. The cessation of most dune accretion after ca. 10 ka suggests reduced seasonality and a more northerly ITCZ position, consistent with evidence from the Cariaco Basin.

Former southwesterly ice flows in the Abitibi–Timiskaming region: implications for the configuration of the late Wisconsinan ice sheet

1986 ◽  
Vol 23 (11) ◽  
pp. 1724-1741 ◽  
Author(s):  
J. J. Veillette
Keyword(s):  
Flow Direction ◽  
Ice Sheet ◽  
Ice Flow ◽  
Almost Everywhere ◽  
Ice Flows ◽  
Show Evidence ◽  
The Cross ◽  
Late Wisconsinan ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Measurements at some 300 cross-striated sites in the Abitibi–Timiskaming area of Quebec and Ontario revealed two former directions of ice flow: an older west-southwest one (230–270°) in the extreme western part of the area, and a younger, widespread south-southwest one (180–220°) in the region west of the Harricana – Lake McConnell glaciofluvial complex. These sets of older striae, whether one or both on the same outcrop, are almost everywhere crossed by marks of a younger ubiquitous flow to the south-southeast (130–170°). On the basis of striae directions measured below an older till and of three dates obtained from intertill (below the surficial till) nonglacial sediments in the Timmins and Matheson areas in Ontario and the Selbaie mine area in Quebec, the oldest west-southwest (230–270°) striae are tentatively associated with the west-southwest flow that deposited this lowermost till in early to mid-Wisconsinan time or earlier.The Harricana – Lake McConnell glaciofluvial system extends from James Bay to the vicinity of North Bay Ontario and probably continues farther south to the Lake Simcoe area. It is strictly an interlobate deglaciation feature and does not result from the converging flows of two coalescing glaciers. At the last glacial maximum the dominant ice-flow direction in the area was probably toward the southwest, across the space occupied by this glaciofluvial system, confirming the flow lines shown by most models of the late Wisconsinan ice sheet. Because none of the cross-striated outcrops showing marks of the former south-southwest (180–220°) and of the last south-southeast (130–170°) movements show evidence of differential weathering and because glacial transport was due to the former southwest movement at several locations, it is proposed that the cross-striations result from the same ice mass subjected to (1) a general change in flow direction from the southwest to the southeast and (2) a complete scission that led ultimately to the deposition of the Harricana – Lake McConnell glaciofluvial system in the interlobate position.

scholarly journals Living on the edge: Comparative phylogeography and phylogenetics of Oreohelix land snails at their range edge in Western Canada

2019 ◽  
Author(s):  
Zach Dempsey ◽  
Cameron Goater ◽  
Theresa Burg
Keyword(s):  
Rocky Mountains ◽  
Its2 Sequence ◽  
Land Snails ◽  
Secondary Contact ◽  
Genetic Lineages ◽  
Range Edge ◽  
Sky Island ◽  
The Last Glacial Maximum ◽  
Cluster 2 ◽  
The Last Glacial

Abstract Background: The biodiversity and distributions of terrestrial snails at local and regional scales are influenced by their low vagility and microhabitat specificity. The accessibility of large-bodied species and their characteristically high levels of genetic polymorphism make them excellent ecological and evolutionary models for studies on the phylogeography, phylogenetics, and conservation of organisms in fragmented populations. This study aims to elucidate the biodiversity, systematics, and distributions of genetic lineages within the genus Oreohelix at the northern and western periphery of their range. Results: We found four mitochondrial clades, three of which are putative subspecies of Oreohelix subrudis. One clade was geographically widespread, occurring within numerous sites in Cypress Hills and in the Rocky Mountains, a second was geographically restricted to the Rocky Mountains in Alberta, and a third was restricted to the Cypress Hills region. A fourth clade was the small-bodied species, O. cooperi. ITS2 sequence and screening data revealed three haplotype clusters, of which one was O. cooperi. Cluster 1 was typical of the first clade and cluster 2 was typical of the second and third clades. ITS2 alleles were shared in a narrow contact zone between the first and second clades, suggestive of hybridization between the two. Conclusions: A sky island known as Cypress Hills, in southeastern Alberta, Canada, is a biodiversity hotspot for terrestrial land snails in the genus Oreohelix. The observed phylogeographic patterns likely reflect reproductive isolation during the Last Glacial Maximum, followed by secondary contact due to passive, long-range dispersal resulting from low vagility, local adaptation, and complex glacial history.

scholarly journals Mitochondrial DNA Diversity of the Nangan Islanders Living in the Mazu Archipelago of the Taiwan Strait

2021 ◽  
pp. 25-27
Author(s):  
Chen Zong-Sian ◽  
Trejaut Jean ◽  
Loo Jun-Hun ◽  
Lai Ying-Hui ◽  
Huang Jin-Yuan ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
East Coast ◽  
Northeast Asia ◽  
Taiwan Strait ◽  
High Genetic Diversity ◽  
The Taiwan Strait ◽  
Relationship Of ◽  
The Last Glacial Maximum ◽  
Very High ◽  
The Last Glacial

This study investigates the genetic relationship of the Mazu peoples on the east coast of China in the Taiwan Strait. Using partial and complete mitochondrial DNA (mtDNA) sequences, we compare Mazu with surrounding East Asia populations. Mazu shows no exclusive affinities with either Southeast or Northeast Asia. High genetic diversity and a very high number of exclusive haplogroups of various Asian origins suggest that Mazu resulted from a process of continuous resettlement that started when it first became an archipelago at the end of the last glacial maximum and that continued till the last century. As a result, genetic drift did not contribute to an exclusive Mazu profile. The structure of haplogroups that show signatures of the Neolithic era (N9a10a), or influx from Island Southeast Asia (F1a4a) suggest recent gene flows and Mazu relationship with it's pre-Neolithic era (presence of pre-E1a or R9/pre-F from Liangdao man) was not seen.

Continental/Cordilleran ice interactions: a dominant cause of westward super-elevation of the last glacial maximum continental ice limit in southwestern Alberta, Canada

2001 ◽  
Vol 30 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Edward C. Little ◽  
Lionel E. Jackson ◽  
Thomas S. James ◽  
Stephen R. Hicock ◽  
Elizabeth R. Leboe
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

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