... Aude LJL Foucher a , Tom Bongers b , Leslie R. Noble a and Michael J. Wilson a , Correspondin... more ... Aude LJL Foucher a , Tom Bongers b , Leslie R. Noble a and Michael J. Wilson a , Corresponding Author Contact Information , E ... into two discrete groups, which was confirmed by canonical and stepwise discriminant function analysis; the values for the Shannon and equitability ...
We have previously isolated from a 1246 adipocyte cDNA library a cDNA done called 154, correspond... more We have previously isolated from a 1246 adipocyte cDNA library a cDNA done called 154, corresponding to a mRNA that increases abun tly at a very early time during the differentiation of 1246 adipocytes and in adipocyte precursors in primary culture. We show here that the mRNA encoded by this cDNA is expressed abundantly and preferen-
Proceedings of The Royal Society B: Biological Sciences, 1996
... from rspb.royalsocietypublishing.org on 1 April 2009 о s u CO «Л PROCEEDINGS THE ROYAL Щ of... more ... from rspb.royalsocietypublishing.org on 1 April 2009 о s u CO «Л PROCEEDINGS THE ROYAL Щ of SOCIETY lu BIOLOGICAL SCIENCES ... within zooids and colonies, although vitellogenic oocyte growth does not usually occur in the absence of a mate (Ryland & Bishop 1990 ...
Visual identification of naturally acquired marks has been a popular if subjective method of anim... more Visual identification of naturally acquired marks has been a popular if subjective method of animal identification and population estimation over the last 40 years. Molecular genetics has also independently developed objective individual marking techniques during the same period. Here, we assess the concordance of individual great white shark (Carcharodon carharias) dorsal fin recognition and identification, using seven microsatellite loci as the independent unbiased arbiter, over a period of 5 years. As a monitoring technique, fin photographs offer a very good individual identification key for white sharks over a relatively short period of time (5 years), matching with genetic data in about 85% of cases, whilst caution and a continuously updated database is required for animal recognition over a longer period.
Proceedings of The Royal Society B: Biological Sciences, 1996
Clonal reproduction is commonly incorporated into the life cycles of many metazoans. However, whe... more Clonal reproduction is commonly incorporated into the life cycles of many metazoans. However, whether and how such highly clonal animals persist in the face of natural enemies remains poorly understood. Here we report the first temporal genetic study of a clonal population, the freshwater bryozoan Cristatella mucedo, and the associated prevalence of a myxozoan parasite. High levels of both clonality and parasitism persisted over a 3 year period. Random amplified polymorphic DNA markers revealed four distinct clones of C. mucedo. The two most common clones varied in abundance with the significantly more common clone in the first year becoming the significantly less common by the third year. There was no evidence that the most common clone was disproportionately infected. These results are discussed in relation to predictions of the Red Queen and the metapopulation dynamics of clonal organisms.
Background: Biomphalaria glabrata is an intermediate snail host for Schistosoma mansoni, one of t... more Background: Biomphalaria glabrata is an intermediate snail host for Schistosoma mansoni, one of the important schistosomes infecting man. B. glabrata/S. mansoni provides a useful model system for investigating the intimate interactions between host and parasite. Examining differential gene expression between S. mansoni-exposed schistosome-resistant and susceptible snail lines will identify genes and pathways that may be involved in snail defences.
Keywords:Carcharodon carcharias;dinucleotides;elasmobranch;genetic markers;great white shark;micr... more Keywords:Carcharodon carcharias;dinucleotides;elasmobranch;genetic markers;great white shark;microsatellitesCarcharodon carcharias;dinucleotides;elasmobranch;genetic markers;great white shark;microsatellites
Recent studies indicate that the flanking region and repeat motif structure of conserved microsat... more Recent studies indicate that the flanking region and repeat motif structure of conserved microsatellite loci are useful for phylogenetic inference. Most comparative studies of microsatellite loci involve relatively closely related species, however, primarily because primers developed for one species often amplify only related species. We describe an analysis of a microsatellite locus in lamniform sharks that we estimate has been conserved for a billion years. Combined analysis of the flanking sequence and repeat motif structure resulted in a gene tree comparable to those reported from similar analyses of other genes. The conservation of the simple sequence repeat (SSR), and of the sequence flanking the SSR, is explained by a low substitution rate in sharks coupled with the possibility that mutations which interrupt perfect repeats are lost by replication slippage. Ó
The freshwater tropical snail Biomphalaria glabrata is an intermediate host for Schistosoma manso... more The freshwater tropical snail Biomphalaria glabrata is an intermediate host for Schistosoma mansoni, the causative agent of human intestinal schistosomiasis, and strains differ in their susceptibility to parasite infection. Changes in gene expression in response to parasite infection have been simultaneously examined in a susceptible strain (NHM1742) and a resistant strain (NHM1981) using a newly developed fluorescent-based differential display method. Such RNA profiling techniques allow the examination of changes in gene expression in response to parasite infection, without requiring previous sequence knowledge, or selecting candidate genes that may be involved in the complex neuroendocrine or defence systems of the snail. Thus, novel genes may be identified. Ten transcripts were initially identified, present only in the profiles derived from snails of the resistant strain when exposed to infection. The differential expression of five of these genes, including HSP70 and several novel transcripts with one containing at least two globin-like domains, has been confirmed by semi-quantitative RT-PCR.
Suppressive subtractive hybridisation was used to examine the genetic basis of susceptibility and... more Suppressive subtractive hybridisation was used to examine the genetic basis of susceptibility and resistance of the Atlantic salmon (Salmo salar) to Gyrodactylus salaris infection. Selected immune relevant genes are listed and two genes, for myeloid leukemia differentiation protein (Mcl-1) and opioid growth factor receptor (OGFr), obtained from the susceptible salmon library were characterised. Both sequences showed high amino acid identity and similarity with human and mouse isoforms, and their possible involvement in the response of salmon to G. salaris is discussed. Quantitative reverse transcriptase-PCR was performed for both genes. Upregulation of Mcl-1 in B1 backcross salmon of the susceptible phenotypic category compared with resistant salmon was demonstrated. The possible relationship of the salmon Mcl-1 and cytokines (interleukin 1b) in the G. salaris-induced host response is discussed. Potential involvement of OGFr in the depletion of mucous cells during prolonged and heavy G. salaris infection, via suppression of DNA synthesis and profound decrease in basal cell proliferation, is proposed. However, only two of six susceptible fish showed high upregulation of OGFr, which might indicate that its expression is localised to sites of wounds resulting from a heavy burden of G. salaris. Ó
Genotyping of 11 microsatellites in 432 offspring from 28 families of the hermaphroditic, freshwa... more Genotyping of 11 microsatellites in 432 offspring from 28 families of the hermaphroditic, freshwater snail Bulinus forskalii detected 10 de novo mutant alleles. This gave an estimated mutation rate of 1.1 × 10−3 per locus per gamete per generation. There was a trend towards repeat length expansion and, unlike most studies, multi-step mutations predominated, suggesting that the microsatellite mutation process does not conform to a strict stepwise mutation model. Interestingly, the ten mutant alleles appear to have arisen from only six independent germline mutation events within the microsatellite array, with seven of them residing in three mutational clusters. Our results extend observations of clustered microsatellite mutations to another taxonomic group and type of mating system, self-fertile gastropods, and provide compelling evidence of premeiotic germline mutations, a phenomenon that could greatly impact upon our understanding of mutation dynamics but which has received little attention.
The similarity in species composition between two communities generally decays as a function of i... more The similarity in species composition between two communities generally decays as a function of increasing distance between them. Parasite communities in vertebrate definitive hosts follow this pattern but the respective relationship in intermediate invertebrate hosts of parasites with complex life cycles is unknown. In intermediate hosts, parasite communities are affected not only by the varying vagility of their definitive hosts (dispersing infective propagules) but also by the necessary coincidence of all their hosts in environmentally suitable localities. As intermediate hosts often hardly move they do not contribute to parasite dispersal. Hence, their parasite assemblages may decrease faster in similarity with increasing distance than those in highly mobile vertebrate definitive hosts. We use published field survey data to investigate distance decay of similarity in trematode communities from three prominent coastal molluscs of the Eastern North-Atlantic: the gastropods Littorina littorea and Hydrobia ulvae, and the bivalve Cerastoderma edule. We found that the similarity of trematode communities in all three hosts decayed with distance, independently of local sampling effort, and whether or not the parasites used the mollusc as first or second intermediate host in their life cycle. In H. ulvae, the halving distance (i.e. the distance that halves the similarity from its initial similarity at 1 km distance) for the trematode species using birds as definitive hosts was approximately two to three times larger than for species using fish. The initial similarities (estimated at 1 km distance) among trematode communities were relatively higher, whereas mean halving distances were lower, compared to published values for parasite communities in vertebrate hosts. We conclude that the vagility of definitive hosts accounts for a high similarity at the local scale, while the strong decay of similarity across regions is a consequence of the low probability that all necessary hosts and suitable environmental conditions coincide on a large scale.
Analysis of differential gene expression in salmon (Salmo salar) blood following infection with t... more Analysis of differential gene expression in salmon (Salmo salar) blood following infection with the monogenean parasite Gyrodactylus salaris, resulted in the isolation of a thymidylate kinase gene not previously described from fish and which showed similarity to an LPS-inducible thymidylate kinase gene isolated from mouse macrophages. This salmon TYKi-like gene may play a role in an innate generalised response to pathogen infection as it was upregulated in salmon following infection with the parasite, and also in response to injection with the immunostimulants LPS and Poly I:C, used to emulate bacterial and viral infections, respectively. The possible role of this gene in the biosynthesis of mitochondrial DNA in activated macrophages, in response to G. salaris infection is discussed.
An enriched microsatellite library was constructed for the Powerful Owl (Aves; Strigiformes: Nino... more An enriched microsatellite library was constructed for the Powerful Owl (Aves; Strigiformes: Ninox strenua ) from which 14 polymorphic microsatellite markers were characterized. Forty individuals (32 unrelated and four pairs of siblings) were genotyped to determine the application of these markers for genetic profiling. The mean observed and expected heterozygosity for unrelated individuals was 0.53 and 0.59, respectively. We demonstrate that this suite of markers is sufficient to unequivocally identify individuals and will be beneficial in assessing the population genetics and reproductive ecology of this species.
Canadian Journal of Zoology-revue Canadienne De Zoologie, 2004
Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which... more Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which act as the vehicle for their development and transmission. They represent an enormous economic and medical burden in developing countries, stimulating much study of snail-trematode interactions. Laboratory-maintained snail-trematode systems and in vitro cell cultures are being used to investigate the molecular dialogue between host and parasite. These dynamic and finely balanced antagonistic relationships, in which parasites strongly influence the physiology of the host, are highly specific and may occasionally demonstrate co-speciation. We consider the mechanisms and responses deployed by trematodes and snails that result in compatibility or rejection of the parasite, and the macroevolutionary implications that they may effect. Although for gastropods the fossil record gives some insight into evolutionary history, elucidation of trematode evolution must rely largely upon molecular approaches, and for both, such techniques have provided fresh and often surprising evidence of their origins and dispersal over time. Co-evolution of snails and trematodes is becoming increasingly apparent at both cellular and population levels; the implications of which are only beginning to be understood for disease control. Untangling the complex interactions of trematodes and snails promise fresh opportunities for intervention to relieve the burden of parasitic disease.
In spite of increasing interest in metapopulation dynamics, the genetic consequences of a metapop... more In spite of increasing interest in metapopulation dynamics, the genetic consequences of a metapopulation structure remain poorly understood. Here we examine the metapopulation genetic structure of the colonial, facultatively sexual freshwater bryozoan Cristatella mucedo, in the Thames basin of southern England, UK. Populations from nine sites were sampled and colonies genetically characterized using random amplified polymorphic DNA (RAPD)-PCR. A total of 78 different clones was detected over all sites. Despite the large number of clones, genetic distances among clones both within and among sites were very small. Nonetheless, no clone was present at more than one site even though C. mucedo has an asexual dispersal propagule, and clones strongly clustered by sites. No consistent pattern of clonal structure was evident, with both the number and equitability of clones varying greatly among sites. Although sites were genetically distinct, population genetic regions were absent, and a Mantel test indicated that there was no relationship between geographical distances among sites and genetic distances among populations. Our results indicate that C. mucedo exists as a classical metapopulation in the Thames basin, with dispersal independent of distance and all sites contributing to the genetic diversity of the metapopulation.
Proceedings of The Royal Society B: Biological Sciences, 1993
The randomly amplified polymorphic DNA (RAPD) assay was used to identify genetic polymorphisms in... more The randomly amplified polymorphic DNA (RAPD) assay was used to identify genetic polymorphisms in three clonal populations of the freshwater bryozoan, Cristatella mucedo, a species with few useful biochemical genetic markers. Of the 19 decamer oligonucleotide primers screened, 13 gave clear, reproducible RAPD profiles. Clonal population structure was evident, and one clone was dominant at each site. Cluster analysis grouped populations from more distant localities separately (Thames Valley and Norfolk), whereas populations from the Thames Valley clustered together. However, even at the regional scale a high degree of relatedness pertained. This work is one of the first RAPD studies of natural populations, and demonstrates the suitability of the technique for examining population structure and geographic variation in clonal taxa.
Journal of Experimental Marine Biology and Ecology, 2009
Understanding the habitat preferences of large marine vertebrates has only recently become tracta... more Understanding the habitat preferences of large marine vertebrates has only recently become tractable with the widespread availability of satellite telemetry for monitoring movements and behaviour. For many species with low population abundances, however, little progress has been made in identifying space use patterns. The endothermic porbeagle shark, Lamna nasus, has declined in the North Atlantic due to severe fishing pressure, with little evidence of recovery. One potential factor exacerbating population decline is area fidelity to coastal waters where fisheries are intensive. We tested for short-term area fidelity by attaching pop-up satellite-linked archival transmitters to four porbeagles in summer 2007, resulting in 175 days total tracking time covering an estimated 10,256 km distance. Throughout July and August the sharks occupied localised areas (8,602 -90,153 km 2 ) within the Celtic Sea, between the south-west UK, south-west Wales and southern Ireland. Only one shark was tracked into the autumn, when it moved into deep water off the continental shelf, then north towards colder latitudes. Sharks occupied a broad vertical depth range (0 -552 m) and water temperatures (9°-19°C). Dives were made frequently from the surface to near the seabed in shelf areas, however, in shelf edge habitats extended periods of time were spent at depths N300 m. Porbeagles showed considerable plasticity in diel depth changes within and between individuals and as a function of habitat type. In addition to no obvious day-night difference in depth occupation, some sharks showed reverse diel vertical migration (DVM) (dawn ascentdusk descent) in well-mixed coastal waters whereas normal DVM (dawn descentdusk ascent) characterised movements into deeper, thermally wellstratified waters. The variable behaviours may reflect the need for different search strategies depending on habitat and prey types encountered. These results show porbeagles are potentially vulnerable to fisheries throughout the summer when they aggregate, and that large scale movement across national boundaries identifies the need for international conservation measures.
... Aude LJL Foucher a , Tom Bongers b , Leslie R. Noble a and Michael J. Wilson a , Correspondin... more ... Aude LJL Foucher a , Tom Bongers b , Leslie R. Noble a and Michael J. Wilson a , Corresponding Author Contact Information , E ... into two discrete groups, which was confirmed by canonical and stepwise discriminant function analysis; the values for the Shannon and equitability ...
We have previously isolated from a 1246 adipocyte cDNA library a cDNA done called 154, correspond... more We have previously isolated from a 1246 adipocyte cDNA library a cDNA done called 154, corresponding to a mRNA that increases abun tly at a very early time during the differentiation of 1246 adipocytes and in adipocyte precursors in primary culture. We show here that the mRNA encoded by this cDNA is expressed abundantly and preferen-
Proceedings of The Royal Society B: Biological Sciences, 1996
... from rspb.royalsocietypublishing.org on 1 April 2009 о s u CO «Л PROCEEDINGS THE ROYAL Щ of... more ... from rspb.royalsocietypublishing.org on 1 April 2009 о s u CO «Л PROCEEDINGS THE ROYAL Щ of SOCIETY lu BIOLOGICAL SCIENCES ... within zooids and colonies, although vitellogenic oocyte growth does not usually occur in the absence of a mate (Ryland & Bishop 1990 ...
Visual identification of naturally acquired marks has been a popular if subjective method of anim... more Visual identification of naturally acquired marks has been a popular if subjective method of animal identification and population estimation over the last 40 years. Molecular genetics has also independently developed objective individual marking techniques during the same period. Here, we assess the concordance of individual great white shark (Carcharodon carharias) dorsal fin recognition and identification, using seven microsatellite loci as the independent unbiased arbiter, over a period of 5 years. As a monitoring technique, fin photographs offer a very good individual identification key for white sharks over a relatively short period of time (5 years), matching with genetic data in about 85% of cases, whilst caution and a continuously updated database is required for animal recognition over a longer period.
Proceedings of The Royal Society B: Biological Sciences, 1996
Clonal reproduction is commonly incorporated into the life cycles of many metazoans. However, whe... more Clonal reproduction is commonly incorporated into the life cycles of many metazoans. However, whether and how such highly clonal animals persist in the face of natural enemies remains poorly understood. Here we report the first temporal genetic study of a clonal population, the freshwater bryozoan Cristatella mucedo, and the associated prevalence of a myxozoan parasite. High levels of both clonality and parasitism persisted over a 3 year period. Random amplified polymorphic DNA markers revealed four distinct clones of C. mucedo. The two most common clones varied in abundance with the significantly more common clone in the first year becoming the significantly less common by the third year. There was no evidence that the most common clone was disproportionately infected. These results are discussed in relation to predictions of the Red Queen and the metapopulation dynamics of clonal organisms.
Background: Biomphalaria glabrata is an intermediate snail host for Schistosoma mansoni, one of t... more Background: Biomphalaria glabrata is an intermediate snail host for Schistosoma mansoni, one of the important schistosomes infecting man. B. glabrata/S. mansoni provides a useful model system for investigating the intimate interactions between host and parasite. Examining differential gene expression between S. mansoni-exposed schistosome-resistant and susceptible snail lines will identify genes and pathways that may be involved in snail defences.
Keywords:Carcharodon carcharias;dinucleotides;elasmobranch;genetic markers;great white shark;micr... more Keywords:Carcharodon carcharias;dinucleotides;elasmobranch;genetic markers;great white shark;microsatellitesCarcharodon carcharias;dinucleotides;elasmobranch;genetic markers;great white shark;microsatellites
Recent studies indicate that the flanking region and repeat motif structure of conserved microsat... more Recent studies indicate that the flanking region and repeat motif structure of conserved microsatellite loci are useful for phylogenetic inference. Most comparative studies of microsatellite loci involve relatively closely related species, however, primarily because primers developed for one species often amplify only related species. We describe an analysis of a microsatellite locus in lamniform sharks that we estimate has been conserved for a billion years. Combined analysis of the flanking sequence and repeat motif structure resulted in a gene tree comparable to those reported from similar analyses of other genes. The conservation of the simple sequence repeat (SSR), and of the sequence flanking the SSR, is explained by a low substitution rate in sharks coupled with the possibility that mutations which interrupt perfect repeats are lost by replication slippage. Ó
The freshwater tropical snail Biomphalaria glabrata is an intermediate host for Schistosoma manso... more The freshwater tropical snail Biomphalaria glabrata is an intermediate host for Schistosoma mansoni, the causative agent of human intestinal schistosomiasis, and strains differ in their susceptibility to parasite infection. Changes in gene expression in response to parasite infection have been simultaneously examined in a susceptible strain (NHM1742) and a resistant strain (NHM1981) using a newly developed fluorescent-based differential display method. Such RNA profiling techniques allow the examination of changes in gene expression in response to parasite infection, without requiring previous sequence knowledge, or selecting candidate genes that may be involved in the complex neuroendocrine or defence systems of the snail. Thus, novel genes may be identified. Ten transcripts were initially identified, present only in the profiles derived from snails of the resistant strain when exposed to infection. The differential expression of five of these genes, including HSP70 and several novel transcripts with one containing at least two globin-like domains, has been confirmed by semi-quantitative RT-PCR.
Suppressive subtractive hybridisation was used to examine the genetic basis of susceptibility and... more Suppressive subtractive hybridisation was used to examine the genetic basis of susceptibility and resistance of the Atlantic salmon (Salmo salar) to Gyrodactylus salaris infection. Selected immune relevant genes are listed and two genes, for myeloid leukemia differentiation protein (Mcl-1) and opioid growth factor receptor (OGFr), obtained from the susceptible salmon library were characterised. Both sequences showed high amino acid identity and similarity with human and mouse isoforms, and their possible involvement in the response of salmon to G. salaris is discussed. Quantitative reverse transcriptase-PCR was performed for both genes. Upregulation of Mcl-1 in B1 backcross salmon of the susceptible phenotypic category compared with resistant salmon was demonstrated. The possible relationship of the salmon Mcl-1 and cytokines (interleukin 1b) in the G. salaris-induced host response is discussed. Potential involvement of OGFr in the depletion of mucous cells during prolonged and heavy G. salaris infection, via suppression of DNA synthesis and profound decrease in basal cell proliferation, is proposed. However, only two of six susceptible fish showed high upregulation of OGFr, which might indicate that its expression is localised to sites of wounds resulting from a heavy burden of G. salaris. Ó
Genotyping of 11 microsatellites in 432 offspring from 28 families of the hermaphroditic, freshwa... more Genotyping of 11 microsatellites in 432 offspring from 28 families of the hermaphroditic, freshwater snail Bulinus forskalii detected 10 de novo mutant alleles. This gave an estimated mutation rate of 1.1 × 10−3 per locus per gamete per generation. There was a trend towards repeat length expansion and, unlike most studies, multi-step mutations predominated, suggesting that the microsatellite mutation process does not conform to a strict stepwise mutation model. Interestingly, the ten mutant alleles appear to have arisen from only six independent germline mutation events within the microsatellite array, with seven of them residing in three mutational clusters. Our results extend observations of clustered microsatellite mutations to another taxonomic group and type of mating system, self-fertile gastropods, and provide compelling evidence of premeiotic germline mutations, a phenomenon that could greatly impact upon our understanding of mutation dynamics but which has received little attention.
The similarity in species composition between two communities generally decays as a function of i... more The similarity in species composition between two communities generally decays as a function of increasing distance between them. Parasite communities in vertebrate definitive hosts follow this pattern but the respective relationship in intermediate invertebrate hosts of parasites with complex life cycles is unknown. In intermediate hosts, parasite communities are affected not only by the varying vagility of their definitive hosts (dispersing infective propagules) but also by the necessary coincidence of all their hosts in environmentally suitable localities. As intermediate hosts often hardly move they do not contribute to parasite dispersal. Hence, their parasite assemblages may decrease faster in similarity with increasing distance than those in highly mobile vertebrate definitive hosts. We use published field survey data to investigate distance decay of similarity in trematode communities from three prominent coastal molluscs of the Eastern North-Atlantic: the gastropods Littorina littorea and Hydrobia ulvae, and the bivalve Cerastoderma edule. We found that the similarity of trematode communities in all three hosts decayed with distance, independently of local sampling effort, and whether or not the parasites used the mollusc as first or second intermediate host in their life cycle. In H. ulvae, the halving distance (i.e. the distance that halves the similarity from its initial similarity at 1 km distance) for the trematode species using birds as definitive hosts was approximately two to three times larger than for species using fish. The initial similarities (estimated at 1 km distance) among trematode communities were relatively higher, whereas mean halving distances were lower, compared to published values for parasite communities in vertebrate hosts. We conclude that the vagility of definitive hosts accounts for a high similarity at the local scale, while the strong decay of similarity across regions is a consequence of the low probability that all necessary hosts and suitable environmental conditions coincide on a large scale.
Analysis of differential gene expression in salmon (Salmo salar) blood following infection with t... more Analysis of differential gene expression in salmon (Salmo salar) blood following infection with the monogenean parasite Gyrodactylus salaris, resulted in the isolation of a thymidylate kinase gene not previously described from fish and which showed similarity to an LPS-inducible thymidylate kinase gene isolated from mouse macrophages. This salmon TYKi-like gene may play a role in an innate generalised response to pathogen infection as it was upregulated in salmon following infection with the parasite, and also in response to injection with the immunostimulants LPS and Poly I:C, used to emulate bacterial and viral infections, respectively. The possible role of this gene in the biosynthesis of mitochondrial DNA in activated macrophages, in response to G. salaris infection is discussed.
An enriched microsatellite library was constructed for the Powerful Owl (Aves; Strigiformes: Nino... more An enriched microsatellite library was constructed for the Powerful Owl (Aves; Strigiformes: Ninox strenua ) from which 14 polymorphic microsatellite markers were characterized. Forty individuals (32 unrelated and four pairs of siblings) were genotyped to determine the application of these markers for genetic profiling. The mean observed and expected heterozygosity for unrelated individuals was 0.53 and 0.59, respectively. We demonstrate that this suite of markers is sufficient to unequivocally identify individuals and will be beneficial in assessing the population genetics and reproductive ecology of this species.
Canadian Journal of Zoology-revue Canadienne De Zoologie, 2004
Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which... more Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which act as the vehicle for their development and transmission. They represent an enormous economic and medical burden in developing countries, stimulating much study of snail-trematode interactions. Laboratory-maintained snail-trematode systems and in vitro cell cultures are being used to investigate the molecular dialogue between host and parasite. These dynamic and finely balanced antagonistic relationships, in which parasites strongly influence the physiology of the host, are highly specific and may occasionally demonstrate co-speciation. We consider the mechanisms and responses deployed by trematodes and snails that result in compatibility or rejection of the parasite, and the macroevolutionary implications that they may effect. Although for gastropods the fossil record gives some insight into evolutionary history, elucidation of trematode evolution must rely largely upon molecular approaches, and for both, such techniques have provided fresh and often surprising evidence of their origins and dispersal over time. Co-evolution of snails and trematodes is becoming increasingly apparent at both cellular and population levels; the implications of which are only beginning to be understood for disease control. Untangling the complex interactions of trematodes and snails promise fresh opportunities for intervention to relieve the burden of parasitic disease.
In spite of increasing interest in metapopulation dynamics, the genetic consequences of a metapop... more In spite of increasing interest in metapopulation dynamics, the genetic consequences of a metapopulation structure remain poorly understood. Here we examine the metapopulation genetic structure of the colonial, facultatively sexual freshwater bryozoan Cristatella mucedo, in the Thames basin of southern England, UK. Populations from nine sites were sampled and colonies genetically characterized using random amplified polymorphic DNA (RAPD)-PCR. A total of 78 different clones was detected over all sites. Despite the large number of clones, genetic distances among clones both within and among sites were very small. Nonetheless, no clone was present at more than one site even though C. mucedo has an asexual dispersal propagule, and clones strongly clustered by sites. No consistent pattern of clonal structure was evident, with both the number and equitability of clones varying greatly among sites. Although sites were genetically distinct, population genetic regions were absent, and a Mantel test indicated that there was no relationship between geographical distances among sites and genetic distances among populations. Our results indicate that C. mucedo exists as a classical metapopulation in the Thames basin, with dispersal independent of distance and all sites contributing to the genetic diversity of the metapopulation.
Proceedings of The Royal Society B: Biological Sciences, 1993
The randomly amplified polymorphic DNA (RAPD) assay was used to identify genetic polymorphisms in... more The randomly amplified polymorphic DNA (RAPD) assay was used to identify genetic polymorphisms in three clonal populations of the freshwater bryozoan, Cristatella mucedo, a species with few useful biochemical genetic markers. Of the 19 decamer oligonucleotide primers screened, 13 gave clear, reproducible RAPD profiles. Clonal population structure was evident, and one clone was dominant at each site. Cluster analysis grouped populations from more distant localities separately (Thames Valley and Norfolk), whereas populations from the Thames Valley clustered together. However, even at the regional scale a high degree of relatedness pertained. This work is one of the first RAPD studies of natural populations, and demonstrates the suitability of the technique for examining population structure and geographic variation in clonal taxa.
Journal of Experimental Marine Biology and Ecology, 2009
Understanding the habitat preferences of large marine vertebrates has only recently become tracta... more Understanding the habitat preferences of large marine vertebrates has only recently become tractable with the widespread availability of satellite telemetry for monitoring movements and behaviour. For many species with low population abundances, however, little progress has been made in identifying space use patterns. The endothermic porbeagle shark, Lamna nasus, has declined in the North Atlantic due to severe fishing pressure, with little evidence of recovery. One potential factor exacerbating population decline is area fidelity to coastal waters where fisheries are intensive. We tested for short-term area fidelity by attaching pop-up satellite-linked archival transmitters to four porbeagles in summer 2007, resulting in 175 days total tracking time covering an estimated 10,256 km distance. Throughout July and August the sharks occupied localised areas (8,602 -90,153 km 2 ) within the Celtic Sea, between the south-west UK, south-west Wales and southern Ireland. Only one shark was tracked into the autumn, when it moved into deep water off the continental shelf, then north towards colder latitudes. Sharks occupied a broad vertical depth range (0 -552 m) and water temperatures (9°-19°C). Dives were made frequently from the surface to near the seabed in shelf areas, however, in shelf edge habitats extended periods of time were spent at depths N300 m. Porbeagles showed considerable plasticity in diel depth changes within and between individuals and as a function of habitat type. In addition to no obvious day-night difference in depth occupation, some sharks showed reverse diel vertical migration (DVM) (dawn ascentdusk descent) in well-mixed coastal waters whereas normal DVM (dawn descentdusk ascent) characterised movements into deeper, thermally wellstratified waters. The variable behaviours may reflect the need for different search strategies depending on habitat and prey types encountered. These results show porbeagles are potentially vulnerable to fisheries throughout the summer when they aggregate, and that large scale movement across national boundaries identifies the need for international conservation measures.
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Papers by Leslie Noble