scholarly journals Variation in palaeo-shorelines explains contemporary population genetic patterns of rocky shore species

2014 ◽  
Vol 10 (6) ◽  
pp. 20140330 ◽  
Author(s):  
Jessica A. Toms ◽  
John S. Compton ◽  
Malcolm Smale ◽  
Sophie von der Heyden
Keyword(s):  
Population Genetic ◽  
Rocky Shore ◽  
Rocky Intertidal ◽  
Secondary Contact ◽  
Intertidal Habitat ◽  
Isolated Populations ◽  
Sea Levels ◽  
Genetic Patterns ◽  
Glacial Periods ◽  
Extant Population

Processes driving and maintaining disjunct genetic populations in marine systems are poorly understood, owing to a lack of evidence of hard barriers that could have shaped patterns of extant population structure. Here, we map two genetically divergent lineages of an obligate rocky shore fish, Clinus cottoides , and model sea-level change during the last 110 000 years to provide the first evidence of a vicariant event along the southern coastline of Africa. Results reveal that lowered sea levels during glacial periods drastically reduced rocky intertidal habitat, which may have isolated populations in two refugia for at least 40 000 years. Contemporary coastal dynamics and oceanography explain secondary contact between lineages. This scenario provides an explanation for the origin of population genetic breaks despite a lack of obvious present-day geographical barriers and highlights the need for including palaeo-oceanography in unravelling extant population patterns.

Microgeographic, Genetic and Morphological-Differentiation of Fresh-Water Snails - the Hydrobiidae of Wilson Promontory, Victoria, South-Eastern Australia

1994 ◽  
Vol 42 (5) ◽  
pp. 557 ◽  
Author(s):  
WF Ponder ◽  
DJ Colgan ◽  
GA Clark ◽  
AC Miller ◽  
T Terzis
Keyword(s):  
Morphological Differentiation ◽  
Geographic Area ◽  
Low Flow ◽  
Secondary Contact ◽  
Shell Shape ◽  
Population Subdivision ◽  
Additional Species ◽  
Sea Levels ◽  
Eastern Australia ◽  
Genetic Patterns

Population differentiation and speciation in freshwater snails in a small geographic area were investigated in a study of the morphology and genetics of 75 populations of hydrobiid snails from streams on Wilsons Promontory, Victoria, Australia. At least four genetically definable species occur in sympatry. One (Fluvidona recta sp. nov.) is genetically isolated from the others and the other three (of which only F: turbata sp. nov. is named) appear to be closely related and distinguished by a nearly fixed allozyme (MPI) difference. Heterozygote frequencies for the diagnostic Mpi locus fall well below Hardy-Weinberg expectations in zones of sympatry. There is significant population subdivision within at least two of the genetic species, but as the partitions are allopatric they are not categorised taxonomically. The situation may be explained by the divergence of upland and lowland populations when sea levels fell during the Pleistocene with subsequent secondary contact and low levels of hybridisation in the contact zones. Generally, there is very low gene flow between even closely adjacent populations and extremely low flow between different catchments, F-ST between populations within the same tributary ranging from 0.02 to 0.14 and within adjacent tributaries of the same catchment ranging from 0.03 to 0.59. Some correlations between allozyme data and measured environmental variables were observed but none of these were consistent over all taxa. Size (shell length) appears to be influenced by environment, but shell shape and the length of the opercular smear are more correlated with genetic patterns. A notable lack of correlation between anatomy and genetic groupings was found, although there was some with shell and opercular morphology. Two additional species (F: gippslandica, sp. nov. and F: foris, sp. nov.) from areas adjacent to the Promontory are used as outgroups.

scholarly journals Host “cleansing zone” at secondary contact: a new pattern in host-parasite population genetics

2020 ◽  
Author(s):  
Jana Martinů ◽  
Jan Štefka ◽  
Anbu Poosakkannu ◽  
Václav Hypša
Keyword(s):  
Population Genetics ◽  
Generation Time ◽  
Population Genetic ◽  
Parasite Population ◽  
Secondary Contact ◽  
Mitochondrial Genomes ◽  
Isolated Populations ◽  
Host Parasite ◽  
Parasite Populations ◽  
Complete Mitochondrial Genomes

AbstractWe introduce a new pattern of population genetic structure in a host-parasite system that can arise after secondary contact (SC) of previously isolated populations. Due to different generation time and therefore different tempo of molecular evolution the host and parasite populations reach different degrees of genetic differentiation during their separation (e.g. in refugia). Consequently, during the SC the host populations are able to re-establish a single panmictic population across the whole recolonized area, while the parasite populations stop their dispersal at the SC zone and create a narrow hybrid zone (HZ). From the host’s perspective, the parasite’s HZ functions on a microevolutionary scale as a “host-cleansing filter”: while passing from area A to area B, the hosts are rid of the area A parasites and acquire the area B parasites. We demonstrate this novel pattern on a model composed of Apodemus mice and Polyplax lice by comparing maternally inherited markers (complete mitochondrial genomes, and complete genomes of vertically transmitted symbiont Legionella polyplacis) with SNPs derived from the louse genomic data. We discuss circumstances which may lead to this pattern and possible reasons why it has been overlooked in the studies on host-parasite population genetics.

scholarly journals Quantifying temporal trends in anthropogenic litter in a rocky intertidal habitat

2020 ◽  
Vol 160 ◽  
pp. 111543 ◽  
Author(s):  
Eleanor A. Weideman ◽  
Vonica Perold ◽  
Aaniyah Omardien ◽  
Lucy K. Smyth ◽  
Peter G. Ryan
Keyword(s):  
Temporal Trends ◽  
Rocky Intertidal ◽  
Intertidal Habitat

Report on Session 2b

1991 ◽  
Vol 7 (1) ◽  
pp. 409-414 ◽  
Author(s):  
D. J. Petley
Keyword(s):  
Ice Sheets ◽  
Weather Conditions ◽  
Land Area ◽  
Geological Time ◽  
Quaternary Period ◽  
Sea Levels ◽  
Stability Of Slopes ◽  
Profound Influence ◽  
Almost All ◽  
Glacial Periods

IntroductionNo part of geological time has had a more profound influence on the engineering characteristics of soils and rocks than the Quaternary period. Large areas of the earth’s surface are covered by superficial deposits of Quaternary age, and almost all surface soils and rocks affected by the changeds in climate which occurred in the Quaternary retain characteristics which have implications for engineering works at the present time.During the Quaternary period, at least five major glaciations occurred. During each glaciation, as the climate became colder, ice sheets spread from the poles and mountainous areas, to be followed by a retreat as warmer weather conditions prevailed during the inter-glacial periods. At the present time, in the Northern hemisphere, ice sheets cover approximately 10% of the total land area, but during the time of maximum glaciation in the Pleistocene, over 30% of the total land area was covered by ice.The volume of water taken up by the ice sheets caused significant variation in sea-levels. It has been estimated that the maximum and minimum sea-levels during the Quaternary were +200 m and -150 m 0D respectively. Indeed, following the main postglacial transgression at the end of the Devensian, the sea has been within 3 m of its present level for only the last 4000 or 5000 years. These large variation in sea-level significantly influenced the development and stability of slopes in coastal areas and inland.

Evolution of Scaphinotus petersi (Coleoptera: Carabidae) and the role of climate and geography in the Madrean sky islands of southeastern Arizona, USA

2013 ◽  
Vol 79 (2) ◽  
pp. 274-283 ◽  
Author(s):  
Sara Gran Mitchell ◽  
Karen A. Ober
Keyword(s):  
Population Genetic ◽  
Regional Climate ◽  
Sky Islands ◽  
Conifer Forests ◽  
Mountain Ranges ◽  
Genetic Patterns ◽  
Madrean Sky Islands ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractGeographically isolated environments such as the conifer forests atop the Madrean “sky islands” in southeastern Arizona provide natural laboratories for studying factors involved in speciation and origins of biodiversity. Using molecular and geospatial analyses, we examine beetle population phylogeny, regional climate records, and the Quaternary paleobiogeography of forests to evaluate four hypothetical scenarios regarding the current geographic and population genetic patterns of Scaphinotus petersi. Scaphinotus petersi is a large, flightless beetle that resides in the Madrean conifer forests above ~ 1900 m asl. Our results do not support the current hypothesis that S. petersi populations found on seven separate mountain ranges are genetically distinct and separated as temperatures warmed after the Last Glacial Maximum (LGM). Rather, we show that only some of the ranges hold genetically distinct populations, and the timing of separation among the populations does not appear to coincide with specific climatic events such as warming trends. In addition, we show that predicted changes to the climate of the Madrean sky islands may result in the disappearance of S. petersi from some of the lower ranges by the end of this century.

Use of RAPD analyses to estimate population genetic parameters in the alfalfa leaf-cutting bee, Megachile rotundata

Genome ◽  
1996 ◽  
Vol 39 (4) ◽  
pp. 655-663 ◽  
Author(s):  
Rui Lu ◽  
Gerald H. Rank
Keyword(s):  
Genetic Distance ◽  
Population Genetic ◽  
Rapd Markers ◽  
Genetic Parameters ◽  
Megachile Rotundata ◽  
Isolated Populations ◽  
Leaf Cutting ◽  
Nucleotide Divergence ◽  
Alfalfa Leaf ◽  
Population Genetic Parameters

RAPD analyses were performed on five geographically isolated populations of Megachile rotundata. We used haploid males of the alfalfa leaf-cutting bee, M. rotundata, to overcome the limitation of the dominance of RAPD markers in the determination of population genetic parameters. Sixteen primers gave rise to 130 polymorphic and 31 monomorphic bands. The unbiased estimators calculated in this study include within- and between-population heterozygosity, nucleotide divergence, and genetic distance. The genetic diversity (H = 0.32–0.35) was found to be about 10 times that of previous estimates (H = 0.033) based on allozyme data. Contrary to the data obtained at the protein level, our results suggest that Hymenoptera do not have a lower level of genetic variability at the DNA level compared with other insect species. Regardless of the different assumptions underlying the calculation of heterozygosity, divergence, and genetic distance, all five populations showed a parallel interrelationship for the three parameters. We conclude that RAPD markers are a convenient tool to estimate population genetic variation in haploid M. rotundata and that with an adequate sample size the technique is applicable to the evaluation of divergence in diploid populations. Key words : Megachile rotundata, RAPD, heterozygosity, genetic distance, nucleotide divergence.

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