Inter-Population Variation in Shell Morphology of the Barnacle Chthamalus Fissus

Jarrett, Jeremiah N.

doi:10.1651/07-2851r.1

Cited by 20 publications

(20 citation statements)

References 23 publications

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“…in invertebrates [92, 93], fishes [7, 94, 95], turtles [96] and crocodilians [97]. Dramatically different morphologies can be expressed in presence or absence of predators in Daphnia water fleas [98–100], barnacle Chthamalus fissus [9], whereas little genetic correspondence is involved in the predator-induced morphological changes [13, 14, 101]. …”

Section: Discussionmentioning

confidence: 99%

Discrete phenotypes are not underpinned by genome-wide genetic differentiation in the squat lobster Munida gregaria (Crustacea: Decapoda: Munididae): a multi-marker study covering the Patagonian shelf

et al. 2016

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BackgroundDNA barcoding has demonstrated that many discrete phenotypes are in fact genetically distinct (pseudo)cryptic species. Genetically identical, isogenic individuals, however, can also express similarly different phenotypes in response to a trigger condition, e.g. in the environment. This alternative explanation to cryptic speciation often remains untested because it requires considerable effort to reject the hypothesis that the observed underlying genetic homogeneity of the different phenotypes may be trivially caused by too slowly evolving molecular markers.The widespread squat lobster Munida gregaria comprises two discrete ecotypes, gregaria s. str. and subrugosa, which were long regarded as different species due to marked differences in morphological, ecological and behavioral traits. We studied the morphometry and genetics of M. gregaria s. l. and tested (1) whether the phenotypic differences remain stable after continental-scale sampling and inclusion of different life stages, (2) and whether each phenotype is underpinned by a specific genotype.ResultsA total number of 219 gregaria s. str. and subrugosa individuals from 25 stations encompassing almost entire range in South America were included in morphological and genetic analyses using nine unlinked hypervariable microsatellites and new COI sequences. Results from the PCA and using discriminant functions demonstrated that the morphology of the two forms remains discrete. The mitochondrial data showed a shallow, star-like haplotype network and complete overlap of genetic distances within and among ecotypes. Coalescent-based species delimitation methods, PTP and GMYC, coherently suggested that haplotypes of both ecotypes forms a single species. Although all microsatellite markers possess sufficient genetic variation, AMOVA, PCoA and Bayesian clustering approaches revealed no genetic clusters corresponding to ecotypes or geographic units across the entire South-American distribution. No evidence of isolation-by-distance could be detected for this species in South America.ConclusionsDespite their pronounced bimodal morphologies and different lifestyles, the gregaria s. str. and subrugosa ecotypes form a single, dimorphic species M. gregaria s. l.. Based on adequate geographic coverage and multiple independent polymorphic loci, there is no indication that each phenotype may have a unique genetic basis, leaving phenotypic plasticity or localized genomic islands of speciation as possible explanations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0836-4) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Discrete phenotypes are not underpinned by genome-wide genetic differentiation in the squat lobster Munida gregaria (Crustacea: Decapoda: Munididae): a multi-marker study covering the Patagonian shelf

et al. 2016

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“…and is indicative of the availability of resources (carrying capacity) within the habitat. Competition for resources including space is a common source of mortality for recruits [38] and some sessile species can reduce mortality from space-limits by displaying morphological plasticity [46], but when progeny vastly outnumber available space, some mortality is inevitable. Maximum population size (assuming densities can be supported and food is not limited) will most likely be determined by the minimum size of an individual [47].…”

Section: Discussionmentioning

confidence: 99%

Predicting Free-Space Occupancy on Novel Artificial Structures by an Invasive Intertidal Barnacle Using a Removal Experiment

et al. 2013

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Artificial structures can create novel habitat in the marine environment that has been associated with the spread of invasive species. They are often located in areas of high disturbance and can vary significantly in the area of free space provided for settlement of marine organisms. Whilst correlation between the amount of free space available and recruitment success has been shown in populations of several marine benthic organisms, there has been relatively little focus on invasive species, a group with the potential to reproduce in vast numbers and colonise habitats rapidly. Invasion success following different scales of disturbance was examined in the invasive acorn barnacle, Austrominius modestus , on a unique art installation located in Liverpool Bay. Population growth and recruitment success were examined by comparing recruitment rates within disturbance clearings of 4 different sizes and by contrasting population development with early recruitment rates over a 10 week period. Disturbed areas were rapidly recolonised and monocultures of A . modestus formed within 6 weeks. The size of patch created during disturbance had no effect on the rate of recruitment, while a linear relationship between recruit density and patch size was observed. Density-dependent processes mediated initial high recruitment resulting in population stability after 8-10 weeks, but densities continued to greatly exceed those reported in natural habitats. Given that artificial structures are likely to continue to proliferate in light of climate change projections, free-space is likely to become more available more frequently in the future supporting the expansion of fast-colonising species.

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“…On top of this, the genotype of certain parasites has been shown to code for more than one phenotype (a trait known as phenotypic plasticity; Stearns, 1992;Poulin, 2007). Different expressions of the same genotype may be triggered by environmental conditions (Jarrett, 2008;van Dijk and Morgan, 2009) and, if certain phenotypes fare better when these conditions change, the proportion of the population expressing this phenotype is likely to increase. The proportion of larvae entering hypobiosis following certain climatic, or immunological, stimuli may be an example of phenotypic plasticity.…”

Section: Genetic Adaptationmentioning

confidence: 99%

Climate change and infectious disease: helminthological challenges to farmed ruminants in temperate regions

Dijk

Sargison

Kenyon

et al. 2010

Animal

197

121

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In the UK, recent mean temperatures have consistently increased by between 18C and 48C compared to the 30-year monthly averages. Furthermore, all available predictive models for the UK indicate that the climate is likely to change further and feature more extreme weather events and a trend towards wetter, milder winters and hotter, drier summers. These changes will alter the prevalence of endemic diseases spatially and/or temporally and impact on animal health and welfare. Most notable among these endemic parasites are the helminths, which have been shown to be very strongly influenced by both the shortterm weather and climate through effects on their free-living larval stages on pasture. In this review, we examine recent trends in prevalence and epidemiology of key helminth species and consider whether these could be climate-related. We identify likely effects of temperature and rainfall on the free-living stages and some key parasite traits likely to determine parasite abundance under changed climatic conditions. We find clear evidence that climate change, especially elevated temperature, has already changed the overall abundance, seasonality and spatial spread of endemic helminths in the UK. We explore some confounders and alternative explanations for the observed patterns. Finally, we explore the implications of these findings for policy makers and the livestock industry and make some recommendations for future research priorities.

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Inter-Population Variation in Shell Morphology of the Barnacle Chthamalus Fissus

Cited by 20 publications

References 23 publications

Discrete phenotypes are not underpinned by genome-wide genetic differentiation in the squat lobster Munida gregaria (Crustacea: Decapoda: Munididae): a multi-marker study covering the Patagonian shelf

Discrete phenotypes are not underpinned by genome-wide genetic differentiation in the squat lobster Munida gregaria (Crustacea: Decapoda: Munididae): a multi-marker study covering the Patagonian shelf

Predicting Free-Space Occupancy on Novel Artificial Structures by an Invasive Intertidal Barnacle Using a Removal Experiment

Climate change and infectious disease: helminthological challenges to farmed ruminants in temperate regions

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