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1.
Understanding physiological and environmental variables that initiate sexual maturity would provide fundamental information
on life history dynamics. The aim of this study was to test the usefulness of the common circumnuclear ring (CNR), an oocytic
structure similar to the Balbiani body, which appears just prior to oocyte development as a predictor of first maturation
in Atlantic herring (Clupea harengus). The relative roles of physiology (e.g. fat) and photoperiod as triggers of maturation were also investigated. Samples were
collected in May 2008 (72°26′–73°84′N/11°26′–18°40′E) and February 2009 (56°12′–59°45′N/00°25′–03°06′W). These data suggested
that thresholds in body size may influence the decision to mature. We also found that short days (winter solstice) may be
the photoperiod trigger for a first-decision window for both Norwegian spring-spawning (NSS) and North Sea autumn-spawning
(NSAS) herring. The second-decision window for NSAS herring maturation appears to be triggered by longer days (spring equinox),
while a decreasing rate of day lengthening may trigger NSS herring maturation. So, photoperiodic cycle is a key determinate
of the timing of maturation in Atlantic herring. 相似文献
2.
Mitochondrial cytochrome oxidase subunit one (COI) sequence, nuclear microsatellites, and amplified fragment length polymorphisms
(AFLPs) were used to evaluate connectivity among nine red abalone (Haliotis rufescens) populations sampled between August 1998 and November 2003 along approximately 1,300 km of California coastline from Crescent
City (41°46′N, 124°12′W) to San Miguel Island (34°02′N, 120°22′W). COI sequences and microsatellite genotypes did not show
significant genetic divergence among nine sampled populations. A subset of five populations spanning the geographic range
of the study was scored for 163 polymorphic AFLP markers. Of these, 41 loci showed significant divergence (P < 0.001) among populations. Still, no AFLP markers were diagnostic for any of the study populations, and assignment tests
did not consistently assign individuals to the correct population. Although the AFLP data are the first to suggest there is
significant genetic differentiation among California red abalone populations, the discordance between the different genetic
markers needs further study before unambiguous conclusions can be drawn with respect to connectivity among the populations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
Assignment of individuals to populations based upon genetic data is an important ecological problem that requires many polymorphic
markers, often more than are available using single locus techniques. To demonstrate the utility of amplified fragment length
polymorphisms (AFLP) in studying larval dispersal and recruitment in coral populations, two sets of AFLP primers were used
to genotype colonies of the coral Agaricia agaricites Linnaeus from three widely separated geographic locations: the Bahamas (23°28′N, 75°42′W) and Key Largo, Florida (24°55′N,
80°31′W—two sites separated by 12 km) in 1995, and the Flower Garden Banks (FGB) in the Gulf of Mexico (27°55′N,93°36′W) in
1997. In addition to adult samples from each site, recruits were collected from settling plates placed on the East FGB for
1 year (1997–1998). The AFLP technique yielded 45 polymorphic markers. An analysis of molecular variance (AMOVA) showed significant
genetic differences among the four adult populations, even between the two Key Largo sites. The recruits were significantly
different from all adult populations except those from the FGB. Discriminant function analysis and the program AFLPOP were
used to assign individuals to populations. Using the adult AFLP-banding patterns to build the statistical models, both procedures
correctly assigned the majority of adults to their respective populations in simulations and assigned all but one of the recruits
to the Flower Garden population from where they were collected . The AFLP technique provides a simple and adaptable population
assignment method for studying recruitment processes in A. agaricites and other coral species.
Electronic Supplementary Material Supplementary material is available for this article at 相似文献
4.
Peter J. Edmunds 《Marine Biology》2007,150(5):783-796
For clonal taxa, the reduced genetic variability associated with clonal proliferation is hypothesized to reduce the ability
to respond to variable conditions, unless a general-purpose genotype (GPG) confers success in multiple environments. In this
study, Corynactis californica (Carlgren 1936) from the subtidal of California was used as a model system to test the hypothesis that clones dampen fluctuations
in fitness through a GPG that facilitates phenotypic plasticity. To achieve this goal, tissue composition, respiration, excretion,
and growth were compared among clones of C.
californica at one site, and a reciprocal transplant experiment was used to test the response of clones to differing conditions at two
sites. All experiments were completed at Santa Catalina Island (N 33°25′, W 118°30′) between April and September 1991. Clones
at a single site differed significantly in multiple traits, varying as much as 1.6-fold in protein content, 3.4-fold in respiration,
and 3.5-fold in excretion. Interestingly, while tissue growth was the most labile trait (differing up to 35.4-fold among clones),
polyp fission rates were not significantly different among clones, in part because fission continued even though tissue growth
was unable to restore polyp size in between divisions. Partial energy budgets revealed that the majority (47–90%) of the daily
energy expenditure was accounted for by respiration, 13–47% by growth, and 0.3–14% by excretion. In the transplant experiment,
reaction norms revealed strong effects of the environment on some traits but not others, notably with growth differing between
sites in a pattern that differed among clones, and excretion differing between sites; neither respiration nor fission were
affected by transplantation. Partial energy budgets revealed that the energy allocation to respiration varied between sites
in a pattern that differed among clones, and a similar trend was evident for tissue growth. Together, these results demonstrate
that clones of C. californica have markedly different phenotypes and exploit phenotypic plasticity to maintain relatively constant fission rates, even
though tissue growth varies greatly among clones and between environments. While these findings support the GPG hypothesis
for clones of C. californica—at least based on relative fitness achieved through asexual proliferation—this conclusion depends on the extent to which
polyps are successful when they have low rates of tissue growth. 相似文献
5.
Spatial distribution and temporal variation of epibenthic assemblages of coralligenous biogenic rocky outcrops occurring in
the northern Adriatic Sea (45°04′–45°24′N; 12°23′–12°43′E) were investigated by photographic sampling from 2003 to 2006 at
12 randomly selected sites. The dominant reef-forming organisms were the encrusting calcareous algae (Lithophyllum stictaeforme, Lithothamnion minervae and Peyssonnelia polymorpha), while the main bioeroders were boring sponges (Cliona viridis, C. celata, C. thoosina, C. rhodensis, Piona vastifica) and the bivalve Gastrochaena dubia. Composition of the assemblages varied thorough years and among sites. Spatial heterogeneity, at local and regional scale,
prevailed over temporal variation. This variability was related both to the geo-morphological features of the outcrops and
to environmental variables. Sites clearly differed in the percent cover of reef builder and bioeroder species while only limited
temporal variation within site was found. Some taxa revealed complex intra-site temporal trends. These results provide valuable
information on the diversity and variability of epibenthic assemblages of the northern Adriatic coralligenous reefs, essential
for the management and conservation of these unique biogenic habitats. 相似文献
6.
T. Knowles M. J. Leng M. Williams P. D. Taylor H. J. Sloane B. Okamura 《Marine Biology》2010,157(6):1171-1180
This is the first investigation of how two independent proxies for seawater temperature inference (zooid size variation and
oxygen isotope ratios of skeletal carbonate) relate to the actual measured ranges of temperature experienced by cheilostome
bryozoan colonies. Nine specimens of the bimineralic marine cheilostome bryozoan Pentapora foliacea (Ellis and Solander, 1786) were analysed, collected from ~18-m depth at two localities in Wales, UK—four from Skomer Island
(51°42′510″N, 5°13′42.60″W) and five from Porth Ysgaden, Lleyn Peninsula (52°54′6.75″N, 4°38′47.34″W). The annual range of
temperature implied by zooid size variability provides a good approximation of the actual range of temperature recorded by
a datalogger. However, annual ranges of temperature reconstructed from skeletal oxygen isotope ratios were narrower, typically
not showing the lowest temperatures experienced by the colonies. This can be explained by progressive thickening of zooid
skeletal walls during the life of the colony that homogenises the temperature signal by time-averaging over the lifetime of
the colonies. Our study provides evidence that a combined morphological isotope approach has great potential in the reconstruction
of annual ranges in seawater temperatures from historical and fossil bryozoans, particularly for species that lack ontogenetic
skeletal wall thickening and bimineralic skeletal composition. As cheilostome bryozoans have been common in benthic communities
since the Late Cretaceous, they represent a valuable and underutilised resource for the interpretation of environmental regimes. 相似文献
7.
Field experiments were conducted from dusk to dawn off St. John (18° 18′ 59.32″ N, 64° 43′ 24.5″ W) and Guana Island (18°
28″ 28.31″ N, 64° 34′ 30.83″ W), Virgin Islands from June through August 2008-2010 to assess the sensory cues used by the
nocturnal/crepuscular fish-parasitic gnathiid isopod, Gnathia marleyi, to locate fish hosts. Experimental traps providing both visual and olfactory cues from live French grunts (Haemulon flavioliniatum) attracted significantly more gnathiids than traps providing only visual cues or control traps (empty or with a rock), which
were not significantly different from each other. In another experiment, traps providing both cues and only olfactory cues
attracted significantly more gnathiids than empty control traps, but were not significantly different from each other. Our
findings suggest that during nocturnal and crepuscular periods, visual cues provided by resting or slow-moving fish are not
alone sufficient to attract gnathiids, while olfactory cues alone are. The traps designed for this study offer a new method
of sampling free-living gnathiid isopods. 相似文献
8.
This study reports the first multi-year observations on the reproductive patterns for an Antarctic predator/scavenger, Odontaster validus (Koehler 1912). Seastars were collected monthly from a shallow site (15–20 m depth) near the British Antarctic Survey (BAS) Rothera Research
Station (Adelaide Island, 67°34′S 68°08′W) from July 1997 to January 2001. Reproductive condition, oocyte size frequencies
and spermatogenesis were examined in at least ten seastars each month using histological and image analysis techniques. Gonad
indices (GI) and pyloric caeca indices (PI) were also examined in the same samples. Female and male GIs varied seasonally,
in parallel with a reduction in the proportion of large oocytes and mature sperm in the gonad in August to mid-October following
winter spawning. Despite there being remarkable consistency in the timing of spawning from year to year, differences in the
reproductive condition of individuals were apparent. Patterns in the digestive tissues also varied with season, peaking in
December and reaching a minimum in February in two of the three study years. This weaker annual pattern may partly reflect
the varied diet of this predator/scavenger species, which is not directly dependant on the timing and magnitude of the annual
phytoplankton bloom. Pooled oocyte size distributions and residual analysis suggested that oogenesis progressed over 18–24 months,
with the largest of the two size classes (maximum diameter = 183 μm) being spawned annually. This pattern of oocyte growth
and spawning was previously reported in the early 1960s for an O. validus population from McMurdo Sound, which lies south of Rothera by 10° latitude. The extremely catholic diet of this predator/scavenger
suggests the reproductive patterns of the seastar will be less susceptible to changes in food supply compared to polar suspension
feeders or deposit feeders.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
Calcium carbonate transfer was experimentally examined in hydrothermal mussels Bathymodiolus azoricus, which were collected from 850 m depth at Menez Gwen hydrothermal vent site (31°31′W, 37°50′N) on the Mid Atlantic Ridge in
May 2007. In each of four 10-day experiments, groups of mussels were maintained at atmospheric pressure or re-pressurised
to depths relevant to their site of occurrence, i.e. 850 m depth at Menez Gwen, 1,750 m at Lucky Strike (31°31′W, 37°18′N)
and 2,300 m at Rainbow (31°31′W, 36°13′N). The shells of experimental mussels were perforated and mantle tissue was fixed
for light and TEM studies at days 7 and 10 following the injury. Simultaneously, haemocytes from the extrapallial fluid (EPF)
at the site of induction were studied. At day 7 the response was most intense in the middle fold of the mantle margin and
possibly proportional to hydrostatic pressure. At day 10 the epithelial cells on the mantle surface facing the body cavity
produced copious organic secretions that avidly bound calcium. Haemocyte migration was noted within the mantle tissue, and
the haemocytes at the mantle surface facing the shell had a Ca-positive granular content. Large haemocytes were detected in
the EPF at the injury site, and some showed evidence of an immune reaction while others showed Ca-positive granular content.
These results suggest that haemocytes are involved in shell repair in these deep-sea mussels just as in some freshwater and
shallow marine molluscs. 相似文献
10.
Space limitation in larval settlement can play an important role in the population dynamics of marine species. A novel statistical
test for space limitation based on quadrat counts of individuals is described. The test is based on identifying a significant
relationship between the relative dispersion of quadrat counts and overall mean density. An application to a time series of
quadrat counts of recently settled American lobsters Homarus americanus covering the period 1993–2007 in Casco Bay, Maine, USA (43°45′N; 69°58′W), is presented. For this data set, the null hypothesis
that space is not limiting could not be rejected (P = 0.10). 相似文献
11.
Dana M. Bethea Loraine Hale John K. Carlson Enric Cortés Charles A. Manire James Gelsleichter 《Marine Biology》2007,152(5):1009-1020
To examine variation in diet and daily ration of the bonnethead shark, Sphyrna tiburo (Linnaeus 1758), animals were collected from three areas in the eastern Gulf of Mexico: northwest Florida (∼29°40′N, 85°13′W),
Tampa Bay near Anclote Key (∼28°10′N, 82°42.5′W), and Florida Bay (∼24°50′N, 80°48′W) from March through September, 1998–2000.
In each area, diet was assessed by life stage (young-of-the year, juveniles, and adults) and quantified using five indices:
percent by number (%N), percent by weight (%W), frequency of occurrence (%O), index of relative importance expressed on a
percent basis (%IRI), and %IRI based on diet category (%IRIDC). Diet could not be assessed for young-of-the-year in Tampa Bay or Florida Bay owing to low sample size. Diet analysis showed
an ontogenetic shift in northwest Florida. Young-of-the-year stomachs from northwest Florida (n = 68, 1 empty) contained a mix of seagrass and crustaceans while juvenile stomachs (n = 82, 0 empty) contained a mix of crabs and seagrass and adult stomachs (n = 39, 1 empty) contained almost exclusively crabs. Crabs made up the majority of both juvenile and adult diet in Tampa Bay
(n = 79, 2 empty, and n = 88, 1 empty, respectively). Juvenile stomachs from Florida Bay (n = 72, 0 empty) contained seagrass and a mix of crustaceans while adult stomachs contained more shrimp and cephalopods (n = 82, 3 empty). Diets in northwest Florida and Tampa Bay were similar. The diet in Florida Bay was different from those in
the other two areas, consisting of fewer crabs and more cephalopods and lobsters. Plant material was found in large quantities
in all stomachs examined from all locations (>15 %IRIDC in 6 of the 7 life stage-area combinations, >30 %IRIDC in 4 of the 7 combinations, and 62 %IRIDC in young-of-the-year diet in northwest Florida). Using species- and area-specific inputs, a bioenergetic model was constructed
to estimate daily ration. Models were constructed under two scenarios: assuming plant material was and was not part of the
diet. Overall, daily ration was significantly different by sex, life stage, and region. The bioenergetic model predicted increasing
daily ration with decreasing latitude and decreasing daily ration with ontogeny regardless of the inclusion or exclusion of
plant material. These results provide evidence that bonnetheads continuously exposed to warmer temperatures have elevated
metabolism and require additional energy consumption to maintain growth and reproduction.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
The growth rates of the morphologically similar scyllarid lobsters Ibacus peronii (Leach, 1815) and I. chacei (Brown and Holthuis, 1998) are described using data from a tag/recapture study and from tagged lobsters kept in captivity.
Within particular size classes, we found no differences in moult increments between male and female I. peronii nor between male and female I. chacei. Small individuals of both species always had larger moult increments than larger individuals. For I. peronii, females moulted more frequently than males, and smaller size classes moulted more frequently than larger size classes. Female
I. peronii therefore grew more quickly than males and reached their estimated size at sexual maturity (51 mm carapace length) after
∼2 yr. Moulting of I. peronii was seasonal, with most lobsters (96.3%) moulting between October and January. We found no differences in growth rates of
I. peronii at two locations along the east coast of Australia: Coffs Harbour in New South Wales (30°18′S; 153°08′E), and Lakes Entrance
in Victoria (37°53′S; 148°00′E). For I. chacei, we found no differences in the frequency of moulting between males and females and, because we also found no differences
in the moult increments between males and females, the growth rates of both sexes were the same.
Received: 14 August 1999 / Accepted: 20 January 2000 相似文献
13.
J. Antonio Baeza 《Marine Biology》2008,153(3):387-395
A previous study predicted the evolution of monogamy in symbiotic crustaceans inhabiting scarce, relatively small hosts in
tropical environments where predation risk away from hosts is high. This prediction was tested in the shrimp Pontonia margarita, which inhabits the pearl oyster Pinctada mazatlanica. A total of 68 oysters were collected from the intertidal and shallow subtidal at two islands (Islas Secas [N 27° 55′, W
82° 03′] and Isla de La Coiba [N 27° 50′, W 97° 03′]) off the eastern tropical Pacific coast on 15 and 17 March 2007, respectively.
The population structure, distribution, male-female association pattern, and relative growth of the major claw and pleura
of the second abdominal segment of each shrimp retrieved were examined. Shrimps were found as heterosexual pairs in the mantle
cavity of hosts more frequently than would be expected by chance alone. Males occurred with females in the same host, independent
of the reproductive condition of the female or the stage of development of brooded embryos. This observation, and strong correlations
between the host and shrimp body size in both males and females suggest a long-term association between males and females
in each host. Sexual dimorphism in body size was minor, with males being just slightly smaller than females. In agreement
with predictions for monogamous species, the major claw of males did not display positive allometry, which has been generally
reported for polygamous shrimps. In turn, the pleura of the second abdomen presented negative allometry in males but positive
allometry in females. All available information suggests that Pontonia margarita has a socially monogamous mating system with males and females forming exclusive pairs in their hosts. 相似文献
14.
Andrea Gori Sergio Rossi Cristina Linares Elisa Berganzo Covadonga Orejas Mark RT Dale Josep-Maria Gili 《Marine Biology》2011,158(8):1721-1732
In the Western Mediterranean Sea, the gorgonian Eunicella singularis (Esper, 1794) is found at high densities on sublittoral bottoms at depths from 10 to 70 m. Shallow colonies have symbiotic
zooxanthellae that deeper colonies lack. While knowledge of the ecology of the shallow populations has increased during the
last decades, there is almost no information on the ecology of the deep sublittoral populations. In October and November 2004
at Cap de Creus (42°19′12″ N; 03°19′34″ E), an analysis of video transects made by a remotely operated vehicle showed that
shallow populations (10–25 m depth) were dominated by small, non-reproductive colonies, while deep sublittoral populations
(50–67 m depth) were dominated by medium-sized colonies. Average and maximum colony heights were greater in the deeper populations,
with these deeper populations also forming larger patch sizes and more extensive regions of continuous substrate coverage.
These results suggest that shallow habitats are suitable for E. singularis, as shown by the high recruitment rate, but perturbations may limit or delay the development of these populations into a
mature stage. This contrasts with the deep sublittoral habitats where higher environmental stability may allow the development
of mature populations dominated by larger, sexually mature colonies. 相似文献
15.
The temperate sea anemone Anthopleura elegantissima is facultatively symbiotic with unicellular algae. Symbiotic A. elegantissima can supplement heterotrophic feeding with excess photosynthate from their algal partners, while asymbiotic individuals must
rely solely on heterotrophy. A. elegantissima individuals were collected from Swirl Rocks, Washington (48°25′6″ N, 122°50′58″ W) in July 2010, and prey capture and feeding
characteristics were measured to determine whether asymbiotic individuals are more efficient predators. Feeding abilities
were then measured again after a 3-week exposure to full sunlight or shaded conditions. Freshly collected asymbiotic anemones
had larger nematocysts, but symbiotic individuals showed greater nematocyte sensitivity. Sunlight enhanced digestion and reduced
cnida density in all anemones regardless of symbiotic state. Results suggest that the phototropic potential of A. elegantissima, as influenced by symbiotic condition, has little effect on heterotrophic capacity. The anemones appear to maximize heterotrophic
energy input independent of the presence or identity of their algal symbionts. 相似文献
16.
Domoic acid in benthic flatfish on the continental shelf of Monterey Bay,California, USA 总被引:1,自引:0,他引:1
Within Monterey Bay, California, USA, the food web transfer of domoic acid (DA), a neurotoxin produced by diatoms of the genus
Pseudo-nitzschia, has led to major mortality events of marine mammals and birds. Less visible, and less well known, is whether invertebrates
and fish associated with the benthos are also affected by blooms of DA-producing Pseudo-nitzschia spp. This study examines the presence of DA in benthic flatfish offshore of Davenport, California, (37°0′36″N, 122°13′12″W)
and within Monterey Bay, California (36°45′0″N, 122°1′48″W), including species that feed primarily in the sediment (benthic-feeding)
and species that feed primarily in the water column (benthopelagic-feeding). Flatfish caught between 10 December 2002 and
17 November 2003 at depths of 30–180 m had concentrations of DA in the viscera ranging from 3 to 26 μg DA g−1 of viscera. Although the DA values reported are relatively low, benthic-feeding flatfish were frequently contaminated with
DA, especially as compared with the frequency of contamination of flatfish species that feed in the water column. Furthermore,
on days in which both benthic-feeding and benthopelagic-feeding flatfish were collected, the former had significantly higher
concentrations of DA in the viscera. Curlfin turbot, Pleuronicthys decurrens, the flatfish with both the highest level and frequency of DA contamination, are reported to feed exclusively on polychaetes,
suggesting that these invertebrates may be an important vector of the toxin in benthic communities and may pose a risk to
other benthic-feeding organisms.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Pat M. Fidopiastis Daniel J. Bezdek Michael H. Horn Judith S. Kandel 《Marine Biology》2006,148(3):631-642
The zebraperch, Hermosilla azurea Jenkins and Evermann, a warm-temperate marine fish species with a strictly macroalgal diet, has a relatively long digestive
tract with an enlarged hindgut and an associated blind caecum (HC). In zebraperch sampled off Santa Catalina Island, California
(33°19′42′′N; 118°18′37′′W) in years 1995 through 2001, direct cell counts, gut epithelium assessment of bacterial attachment,
and short-chain fatty acid (SCFA) analyses verified that the zebraperch HC possesses a dense and morphologically diverse,
fermentative microbiota. Bacterial cell counts and morphological diversity were significantly higher in HC contents compared
to anterior gut regions, suggesting that microbial populations were growing along the digestive tract. Similarly, electron
micrographs of the HC epithelium revealed attached microbes, further supporting the possibility that these organisms constitute
resident microbiota. Five different SCFAs were detected in all three regions of the digestive tract, but levels were up to
three times greater in HC contents. Acetate was consistently the prevailing SCFA in all gut regions. Sequence analysis of
bacterial 16S rDNA was used to identify predominant bacterial groups in HC contents. Of the seven main bacterial types identified,
Enterovibrio spp. were the dominant bacteria in HC contents followed by species of Bacteroides,Faecalibacterium, and Desulfovibrio. Taken together, our findings show that the zebraperch HC harbors a consortium of microbes that appears to assist in the
breakdown of algal polysaccharides in the herbivorous diet of the fish. 相似文献
18.
Hawksbill sea turtles (Eretmochelys imbricata) nesting in Barbados (Needham’s Point, 13° 04′ 41.33′′ N, 59° 36′ 32.69′′W) were outfitted with GPS dataloggers over three
breeding seasons (2008–2010) to track movement during inter-nesting intervals. Most females established spatially restricted
resident areas up current and within 7 km of the nesting beach where they spent the majority of the inter-nesting interval.
Females nesting earlier in the season settled on shallower sites. Only experienced remigrant turtles occupied the most distant
resident areas. Females tracked for multiple inter-nesting intervals exhibited site fidelity, but the area contracted and
the activity of females decreased with each successive interval. Hawksbills may trade off site characteristics with distance
from the nesting beach and reduce activity over the course of the breeding season to optimise energy reserves during inter-nesting
intervals. 相似文献
19.
Carolina Briones Ricardo Gui?ez Orlando Garrido Pablo A. Oyarzún Jorge E. Toro Montse Pérez 《Marine Biology》2012,159(8):1865-1870
For the first time in a marine bivalve species, geographic intraspecific variation in sperm morphology in the Chilean mussel, Perumytilus purpuratus, is reported. Samples were obtained in December 2010 from the rocky intertidal at three locations: Antofagasta (23o44′01.08′′S, 70o26′26.11′′W), Valparaíso (32o57′23.07′′S, 71o33′01.86′′W), and Valdivia (39°50′44.26′′S, 73°25′51.99′′W). Scanning electron microscopy was used to describe sperm traits, and genetic data were obtained by sequencing a 16S mtDNA 427-bp fragment. The results showed geographic intraspecific variation with two statistically significant patterns of genetically differentiated sperm morphologies. One genetic clade was found for Antofagasta and Valparaíso, displaying a unique sperm morphotype with a short acrosome accounting for 26 % of the head length, and the other from Valdivia, with a larger acrosome occupying 47 % of the head length. These results will lead to new research to distinguish among alternative hypotheses: the presence of cryptic species, incipient speciation, or a polymorphism in sperm traits of P. purpuratus. 相似文献
20.
Anne Marie Power Karen McCrann David McGrath Ruth M. O’ Riordan Christina Simkanin Alan A. Myers 《Marine Biology》2011,158(10):2149-2160
This study examined how the species composition of an intertidal barnacle guild varied according to physical gradients in
the environment at small scales governed by microclimates, medium scales of wave exposure and large scales of latitude. Barnacle
distributions at small and medium scales were sampled in Ireland between 51°29′ and 52°44′N and 6°50′ and 10°08′W. Sampling
on European shores spanned ~18° latitude from 37°05′ to 55°16′N. Barnacle surveys mainly took place in 2003–2004. An index
of wave fetch was calculated along the wave exposure gradient using a digital coastline-based model that was supported by
a biological exposure scale. A ‘dryness’ index was defined according to mean monthly wind speed, fetch along the average wind
direction and mean monthly air or sea surface temperatures for 2 years (January 2001–December 2002) which is the period when
the most recent adults in the barnacle community would have settled and grown to adulthood. The proportion of the dry-loving
barnacle Chthamalus montagui Southward increased within the barnacle guild at all scales as the habitat became warmer and drier. Barnacle densities were
high in all habitats, mean densities ranged from a minimum of 4.16 cm−2 on moderately exposed shores to a maximum of 6.27 cm−2 in sunlit or south-facing microclimates. Percentage cover of barnacles across the gradient of latitudes was usually >70%.
The results suggest that the distribution and abundance of interacting barnacle species on European coasts is strongly controlled
by abiotic factors, most likely temperature and desiccation. 相似文献