Genetic-Variation in Yabbies, Cherax-Destructor and C-Albidus (Crustacea, Decapoda, Parastacidae), Indicates the Presence of a Single, Highly Sub-Structured Species

1994 ◽  
Vol 42 (6) ◽  
pp. 745 ◽  
Author(s):  
NJH Campbell ◽  
MC Geddes ◽  
M Adams
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Morphological Variability ◽  
South Australia ◽  
Significant Heterogeneity ◽  
Freshwater Crayfish ◽  
Drainage Basins ◽  
Cherax Destructor ◽  
Variable Morphology ◽  
High Degree

The high degree of morphological variability exhibited by yabbies (Cherax destructor Clark and C. albidus Clark) prompted this investigation of genetic variation, specifically addressing the taxonomy and population structure of these freshwater crayfish. Yabbies from 14 localities in South Australia and Victoria were classified morphologically and examined electrophoretically at 35 gene loci. Morphometric analysis confirmed the existence of two morphotypes with allopatric distributions. Genetic divergence between morphotypes was relatively low (average fixed differences = 4.72%, average Nei D = 0.085) compared with known interspecific levels-both generally and within the genus Cherax-and levels of divergence between populations within the morphotypes. Subspecific status for albidus is consequently advocated. This species shows evidence of a high degree of genetic fragmentation, with significant heterogeneity occurring at two or more loci between even the closest localities. Gene flow appears to be severely restricted even within drainage basins and a 'stepping-stone' model of population structure may be appropriate. This high degree of genetic fragmentation may explain the variable morphology of this species although phenotypic plasticity could also play a role. Genetic variation was chaotically distributed (the only consistent geographic pattern of divergence corresponding to the albidus morphotype), probably reflecting numerous translocations of this species. The results highlight the need for taxonomy and management to be based on genetic as well as morphological subdivisions.

scholarly journals Analysis of mitochondrial control region nucleotide sequences from Baffin Bay beluga, (Delphinapterus leucas): detecting pods or sub-populations?

2002 ◽  
Vol 4 ◽  
pp. 39 ◽  
Author(s):  
Per Jakob Palsbøll ◽  
Mads Peter Heide-Jørgensen ◽  
Martine Bérubé
Keyword(s):  
Population Structure ◽  
Control Region ◽  
Genetic Heterogeneity ◽  
Mitochondrial Control Region ◽  
Delphinapterus Leucas ◽  
Significant Heterogeneity ◽  
Management Units ◽  
Baffin Bay ◽  
The One ◽  
High Degree

We report the results of an analysis of the variation in the nucleotide sequence of the mitochondrial control region obtained in 218 samples collected from belugas, Delphinapterus leucas, around the Baffin Bay. We detected multiple instances of significant heterogeneity in the distribution of genetic variation among the analyzed mitochondrial control region sequences on a spatial as well as temporal scale indicating a high degree of maternal population structure. The detection of significant levels of heterogeneity between samples collected in different years but within the same area and season was unexpected. Re-examination of earlier results presented by Brown Gladden and coworkers also revealed temporal genetic heterogeneity within the one area where sufficient (n>15) samples were collected in multiple years. These findings suggest that non-random breeding and maternally directed site-fidelity are not the sole causes of genetic heterogeneity among belugas but that a matrilineal pod structure might cause significant levels of genetic heterogeneity as well, even within the same area. We propose that a maternal pod structure, which has been shown to be the cause of significant genetic heterogeneity in other odontocetes, may add to the overall level of heterogeneity in the maternally inherited DNA and hence that much of the spatial heterogeneity observed in this and previous studies might be attributed to pod rather than population structure. Our findings suggest that it is important to estimate the contribution of pod structure to overall heterogeneity before defining populations or management units in order to avoid interpreting heterogeneity due to sampling of different pods as different populations/management units.

scholarly journals Predation of two common native frog species (Litoria ewingi and Crinia signifera) by freshwater invertebrates

2014 ◽  
Vol 62 (6) ◽  
pp. 483 ◽  
Author(s):  
Natasha J. Wilson ◽  
Jamie E. Seymour ◽  
Craig R. Williams
Keyword(s):  
Aquatic Invertebrates ◽  
South Australia ◽  
Aquatic Invertebrate ◽  
Freshwater Crayfish ◽  
Life Stages ◽  
Freshwater Invertebrates ◽  
Invertebrate Predator ◽  
Cherax Destructor ◽  
Invertebrate Predators ◽  
Frog Species

The primary aim of this study was to identify aquatic invertebrate predators of amphibian eggs and tadpoles in an area of South Australia. The presence and abundance of aquatic invertebrates was monitored at four field sites for a period of 5–6 months; this revealed notonectids, freshwater crayfish and odonates to be amongst the most common invertebrate predator types. The ability of these predators to consume eggs and tadpoles of the native Australian frogs Litoria ewingi and Crinia signifera was then investigated. Freshwater crayfish (Cherax destructor) were the most prolific consumers of frog eggs and tadpoles. The notonectid Enithares woodwardi significantly impacted tadpole survivorship for both species while Anisops sp. was less successful at capturing and consuming these tadpoles. Caddisfly nymphs (Lectrides varians and Leptorussa darlingtoni) reduced egg survivorship but not to the same extent as C. destructor. Unlike some predators, which prey upon particular life stages, freshwater crayfish are large, polytrophic omnivores that can act as important predators of both anuran eggs and tadpoles. Given that predation is a key source of mortality in juveniles, identification of likely common predators is useful for understanding the regulation of amphibian populations.

Allozyme variation and an estimate of the inbreeding coefficient in the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae)

1995 ◽  
Vol 85 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Philippe Borsa ◽  
D. Pierre Gingerich
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Population Genetic ◽  
New Caledonia ◽  
Allozyme Variation ◽  
Inbreeding Coefficient ◽  
Hypothenemus Hampei ◽  
Coffee Berry ◽  
Biological Features ◽  
High Degree

AbstractSeven presumed Mendelian enzyme loci (Est-2, Est-3, Gpi, Idh-l, Idh-2, Mdh-2 and Mpi) were characterized and tested for polymorphism in coffee berry borers, Hypothenemus hampei (Ferrari), sampled in Côte d′Ivoire, Mexico and New Caledonia. The average genetic diversity was H = 0.080. Two loci, Mdh-2 and Mpi were polymorphic, and thus usable as genetic markers. The population structure of H. hampei was analysed using Weir & Cockerham's estimators of Wright's F-statistics. A high degree of inbreeding (f = 0.298) characterized the elementary geographic sampling unit, the coffee field. The estimate of gene flow between fields within a country was Nm = 10.6 and that between countries was Nm = 2. The population genetic structure in H. hampei could be related to its known population biological features and history.

Phylogeny of the Australian freshwater crayfish Cherax destructor-complex (Decapoda : Parastacidae) inferred from four mitochondrial gene regions

2005 ◽  
Vol 19 (3) ◽  
pp. 209 ◽  
Author(s):  
Thuy T. T. Nguyen ◽  
Christopher M. Austin
Keyword(s):  
16S Rrna ◽  
Cytochrome Oxidase ◽  
Mitochondrial Gene ◽  
Large Subunit ◽  
Strong Support ◽  
Interspecific Variation ◽  
Rrna Gene ◽  
Freshwater Crayfish ◽  
Cherax Destructor ◽  
Australian Freshwater

The phylogenetic relationships among 32 individuals of Australian freshwater crayfish belonging to the Cherax destructor-complex were investigated using a dataset comprising sequences from four mitochondrial gene regions: the large subunit rRNA (16S rRNA), cytochrome oxidase I (COI), adenosine triphosphatase 6 (ATPase 6), and cytochrome oxidase III (COIII). A total of 1602 bp was obtained, and a combined analysis of the data produced a tree with strong support (bootstrap values 94–100%) for three divergent lineages, verifying the phylogenetic hypotheses of relationships within the C. destructor species-complex suggested in previous studies. Overall, sequences from the 16S rRNA gene showed the least variation compared to those generated from protein coding genes, which presented considerably greater levels of divergence. The level of divergence within C. destructor was found to be greater than that observed in other species of freshwater crayfish, but interspecific variation among species examined in the present study was similar to that reported previously.

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