A comparison of population differentiation in two shore crab species with contrasting distribution along the Portuguese coast, using two morphological methodologies

2009 ◽  
Vol 60 (8) ◽  
pp. 833 ◽  
Author(s):  
Inês C. Silva ◽  
Stephen J. Hawkins ◽  
José Paula
Keyword(s):  
Population Differentiation ◽  
Carcinus Maenas ◽  
Continuous Distribution ◽  
Morphological Differentiation ◽  
Shore Crab ◽  
Clinal Variation ◽  
Rocky Shores ◽  
Portuguese Coast ◽  
Pachygrapsus Marmoratus ◽  
Variation Explained

Along the Portuguese coast, Pachygrapsus marmoratus has a continuous distribution on rocky shores. In contrast, Carcinus maenas has a discontinuous distribution, inhabiting estuaries. Surveys along a coastal latitudinal gradient were made to assess the effect of the distribution pattern on population differentiation of these two species. Population differentiation was studied using two different morphometric methodologies: linear-based morphometrics and landmark-based morphometrics. The linear-based analysis revealed no significant morphological differentiation among the eleven P. marmoratus populations. Landmark-based analysis showed that the northern and central populations were more similar in shape than the southern populations. Nevertheless, there was still some overlap in shape that could be due to the continuous distribution of P. marmoratus along the coast, promoting population panmixia. In C. maenas, both morphometric techniques revealed the existence of morphological differentiation among populations. This shape differentiation showed a clinal variation, explained by a higher degree of isolation of populations that might be due to limited larval flow between them. Environmental factors may also play an important role in causing variation of shape. Landmark-based morphometrics yielded stronger evidence of morphological differences among forms than a linear approach, suggesting that this method may be more suitable for analysis of body shape.

Population dynamics of the shore crab Pachygrapsus marmoratus (Brachyura: Grapsidae) in the central Portuguese coast

2002 ◽  
Vol 82 (2) ◽  
pp. 229-241 ◽  
Author(s):  
Augusto A.V. Flores ◽  
José Paula
Keyword(s):  
Population Dynamics ◽  
Size Structure ◽  
Shore Crab ◽  
Late Winter ◽  
Rocky Shores ◽  
Study Region ◽  
Frequency Distributions ◽  
Portuguese Coast ◽  
Pachygrapsus Marmoratus ◽  
Young Of The Year

The population dynamics of the shore crab Pachygrapsus marmoratus was studied at two different rocky shores, Cabo Raso and Avencas, within the central Portuguese coast. The population structure at these shores, obtained by pooling monthly samples, revealed marked discrepancies. Unimodal, right-skewed size–frequency distributions at Avencas contrasts with the bimodal distributions obtained at Cabo Raso, corresponding to early recruits and larger adults. Recruitment timing and intensity together with habitat complexity are probable causes of the differences observed. At Cabo Raso an intense recruitment season was recorded from September to November, but very small juveniles were always present in samples. Monthly polymodal distributions are apparent but the size structure too complex to identify age groups through the sampling period. At Avencas, the influx of new juveniles is temporally restricted and year groups recognizable from main recruitment events taking place around October. Young-of-the-year crabs grow quickly to mature size and join the reproductive stock in the next breeding season from late March to early September in the study region. The growth pattern in both sexes follows a seasonal trend with minimum growth during the breeding months and maximum growth rates from late winter to early spring. Life span may reach four years, probably more in males. At Avencas, population maintenance seems to be highly dependent on favourable conditions promoting adequate settlement intensity and timing. Early recruitment is presumed to enhance the reproductive output of young-of-the-year individuals which comprise the bulk of breeding crabs. At Cabo Raso settlement rates are much higher and recruitment timing may be less critical since most breeding crabs belong to the 1-y+ class.

Predation: a regulating force of intertidal assemblages on the central Portuguese coast?

2009 ◽  
Vol 89 (8) ◽  
pp. 1541-1548 ◽  
Author(s):  
Sónia A.E. Brazão ◽  
Ana C.F. Silva ◽  
Diana M. Boaventura
Keyword(s):  
Experimental Period ◽  
Rocky Shores ◽  
Community Patterns ◽  
Predator Species ◽  
Potential Predator ◽  
Portuguese Coast ◽  
Significant Control ◽  
Predator Exclusion ◽  
Pachygrapsus Marmoratus ◽  
Exclusion Experiments

Predation has long been recognized as an important biological force driving community patterns in intertidal rocky shores throughout the world. Little is known, however, about the role of predation by mobile marine predators in shaping intertidal prey populations in Portuguese rocky shores. The abundance and population structure of crabs were assessed during nocturnal low-tides on two rocky shores to characterize potential predator species. To assess the effect of predation on intertidal species including limpets, barnacles and mussels, predator exclusion experiments using full cage, partial cage and no cage treatments, were set up for two months on two shores on the central Portuguese coast. Pachygrapsus marmoratus (Fabricius) and Eriphia verrucosa (Forsskål) were the most abundant crabs. Results from predator exclusion experiments suggested that predators do not exert a significant control on abundance of limpets, mussels or barnacles on the midshore during the experimental period. Despite the fact that these crabs are known to feed on the analysed prey, several factors may account for the observed absence of impact on prey abundance and these are discussed.

Genetic patchiness of the shore crab Pachygrapsus marmoratus along the Portuguese coast

2009 ◽  
Vol 378 (1-2) ◽  
pp. 50-57 ◽  
Author(s):  
Inês C. Silva ◽  
Natacha Mesquita ◽  
Christoph D. Schubart ◽  
Maria Judite Alves ◽  
José Paula
Keyword(s):  
Shore Crab ◽  
Portuguese Coast ◽  
Pachygrapsus Marmoratus ◽  
Genetic Patchiness

scholarly journals Gene flow relates to evolutionary divergence among populations at the range margin

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10036 ◽  
Author(s):  
Peter Kaňuch ◽  
Berrit Kiehl ◽  
Anna Cassel-Lundhagen ◽  
Ane T. Laugen ◽  
Matthew Low ◽  
...  
Keyword(s):  
Gene Flow ◽  
Continuous Distribution ◽  
Morphological Differentiation ◽  
Environmental Drivers ◽  
Restricted Gene Flow ◽  
Evolutionary Divergence ◽  
Clinal Variation ◽  
Isolated Populations ◽  
Phenotypic Effect ◽  
Local Adaptations

Background Morphological differentiation between populations resulting from local adaptations to environmental conditions is likely to be more pronounced in populations with increasing genetic isolation. In a previous study a positive clinal variation in body size was observed in isolated Roesel’s bush-cricket, Metrioptera roeselii, populations, but were absent from populations within a continuous distribution at the same latitudinal range. This observational study inferred that there was a phenotypic effect of gene flow on climate-induced selection in this species. Methods To disentangle genetic versus environmental drivers of population differences in morphology, we measured the size of four different body traits in wild-caught individuals from the two most distinct latitudinally-matched pairs of populations occurring at about 60°N latitude in northern Europe, characterised by either restricted or continuous gene flow, and corresponding individuals raised under laboratory conditions. Results Individuals that originated from the genetically isolated populations were always bigger (femur, pronotum and genital appendages) when compared to individuals from latitudinally-matched areas characterised by continuous gene flow between populations. The magnitude of this effect was similar for wild-caught and laboratory-reared individuals. We found that previously observed size cline variation in both male and female crickets was likely to be the result of local genetic adaptation rather than phenotypic plasticity. Conclusions This strongly suggests that restricted gene flow is of major importance for frequencies of alleles that participate in climate-induced selection acting to favour larger phenotypes in isolated populations towards colder latitudes.

Effects of handling during experimental procedures on stress indices in the green shore crab, Carcinus maenas (L)

2021 ◽  
Vol 54 (2) ◽  
pp. 65-85
Author(s):  
Charlotte H. Wilson ◽  
Sarah J. Nancollas ◽  
Molly L. Rivers ◽  
John I. Spicer ◽  
Iain J. McGaw
Keyword(s):  
Carcinus Maenas ◽  
Shore Crab ◽  
Stress Indices

Biochemical responses of the shore crab (Carcinus maenas) in a eutrophic and metal-contaminated coastal system (Óbidos lagoon, Portugal)

2009 ◽  
Vol 72 (5) ◽  
pp. 1471-1480 ◽  
Author(s):  
Patrícia Pereira ◽  
Hilda de Pablo ◽  
Maria Dulce Subida ◽  
Carlos Vale ◽  
Mário Pacheco
Keyword(s):  
Carcinus Maenas ◽  
Shore Crab ◽  
Coastal System ◽  
Biochemical Responses
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