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81.
82.
Natural History: Hobby or Science? 总被引:1,自引:0,他引:1
Jesús Antonio Rivas 《Conservation biology》1997,11(3):811-812
83.
We used microsatellite genetic markers to investigate adult population structure and the formation of a new year-class in
Sebastes mystinus (blue rockfish). Since S. mystinus may live as long as 45 years and reach reproductive age at approximately 5 years, the adult population may contain as many
as eight generations of reproductive adults. We investigated whether the juveniles of the 2000 year-class and the adult population
were genetically homogeneous along the California coast. We sampled approximately 100 juveniles from three sites, two sites
along the Monterey Peninsula (Carmel and Monterey) in central California and one at Fort Ross in northern California, and
approximately 50 adult S. mystinus from five sites throughout the population center. The adult sampling spanned approximately 700 km from the northern Channel
Islands to Fort Bragg. The juveniles showed significant heterogeneity in allele frequencies among distant locations and genetic
homogeneity among adjacent locations. In contrast, the adults showed genetic homogeneity over large distances (San Miguel
Island to Fort Bragg), indicating little limitation of gene flow in this region. Allele frequencies of juveniles differed
from adult samples and in some cases reduced genetic diversity indicative of sweepstakes recruitment (small sample of the
adult reproductive potential). The genetic structure of the 2000 year-class suggests that despite a genetically homogenous
adult population, settled juveniles can be genetically heterogeneous along the California coast. The results also suggest
that the adults, with several year-classes, are capable of maintaining a panmictic population despite the genetic distinctiveness
of individual year-classes. 相似文献
84.
E.?PfeilerEmail author L.?A.?Hurtado L.?L.?Knowles J.?Torre-Cosío L.?Bourillón-Moreno J.?F.?Márquez-Farías G.?Montemayor-López 《Marine Biology》2005,146(3):559-569
The population genetics and historical demography of the swimming crab Callinectes bellicosus from the eastern Pacific were assessed using mitochondrial DNA (mtDNA) sequences from portions of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes. Analysis of molecular variance of sequence data from crabs collected from nine localities, ranging from the upper to lower Gulf of California and the outer coast of the Baja California peninsula, revealed an absence of population structure, suggesting a high level of gene flow over a wide geographic area. Maximum-likelihood estimates of long-term effective population size obtained with the program FLUCTUATE, in addition to highly significant values obtained from neutrality tests (Tajimas D, Fu and Lis D, and Fus FS) and mismatch analysis, are consistent with a population expansion dating to the Pleistocene epoch. Phylogenetic analysis of C. bellicosus sequences using both neighbor-joining and Bayesian methods revealed a widely distributed subclade (clade II) cryptically embedded at low frequency in the main (clade I) population. Although sequence divergence between the two clades was low (1.1% COI; 0.6% Cytb), statistical support for the split was high. The Kimura-2-parameter genetic distance between C. bellicosus and the sympatric and morphologically similar C. arcuatus was high (d=0.17) and similar to the genetic distance between C. bellicosus and the allopatric C. sapidus from the western Atlantic (d=0.18), suggesting an ancient (Miocene) divergence of C. bellicosus and C. arcuatus.Communicated by P.W. Sammarco, Chauvin 相似文献
85.
Scott?A.?ShafferEmail author Yann?Tremblay Jill?A.?Awkerman R.?William?Henry Steven?L.?H.?Teo David?J.?Anderson Donald?A.?Croll Barbara?A.?Block Daniel?P.?Costa 《Marine Biology》2005,147(4):833-843
Light-based archival tags are increasingly being used on free-ranging marine vertebrates to study their movements using geolocation estimates. These methods use algorithms that incorporate threshold light techniques to determine longitude and latitude. More recently, researchers have begun using sea surface temperature (SST) to determine latitude in temperate regions. The accuracy and application of these algorithms have not been validated on free-ranging birds. Errors in both geolocation methods were quantified by double-tagging Laysan (Phoebastria immutabilis Rothschild) and black-footed (P. nigripes Audubon) albatrosses with both leg-mounted archival tags that measured SST and ambient light, and satellite transmitters. Laysan albatrosses were captured and released from breeding colonies on Tern Island, northwestern Hawaiian Islands (23°52N, 166°17W) and Guadalupe Island, Mexico (28°31N, 118°10W) and black-footed albatrosses from Tern Island. Studies were carried out between December 2002 and March 2003. For all birds combined, the mean ± SD great circle (GC) distance between light-based locations and satellite-derived locations was 400±298 km (n=131). Errors in geolocation positions were reduced to 202±171 km (n=154) when light-based longitude and SST-based latitude (i.e. SST/light) were used to establish locations. The SST/light method produced comparable results for two Laysan albatross populations that traveled within distinctly different oceanic regions (open ocean vs more coastal) whereas light-based methods produced greater errors in the coastal population. Archival tags deployed on black-footed albatrosses returned a significantly higher proportion of lower-quality locations, which was attributed to interference of the light sensor on the tag. Overall, the results demonstrate that combining measures of light-based longitude and SST-based latitude significantly reduces the error in location estimates for albatrosses and can provide valid latitude estimates during the equinoxes, when light-based latitude measurements are indeterminate.Communicated by J.P. Grassle, New Brunswick 相似文献
86.
The intertidal molluscan fauna on a sandy-mud beach in Newport Bay, California, USA, is divisible into two vertically distinct species assemblages which correspond to the midlittoral zone and sublittoral fringe observed on rocky coastlines and exposed sandy beaches. The species assemblage comprising the midlittoral zone is unusual, however, in that the numerically dominant species are not confined to this zone but range downward through the sublittoral fringe. The two species assemblages are vertically separated at +0.5 to +1.0 ft (+0.15 to +0.30 m; relative to 0.0 tidal datum at mean lower low water), which is higher than previously observed for the separation between the midlittoral zone and sublittoral fringe on rocky shores and exposed sandy beaches. The species composition of some of the samples at +0.5 and +1.0 ft (+0.15 and +0.30 m) was intermediate between samples higher and lower on the beach, while several samples were devoid of molluscs altogether. Additionally, the surface sedimentary environment changes in terms of an increased percent silt-clay fraction and higher sorting coefficients below +0.5 ft (+0.15 m). Since infaunal zonation is correlated with tidal height at the substrate surface, environmental factors operative at the surface are probably most important in influencing the zonation on this beach. 相似文献
87.
The leopard shark (Triakis semifasciata) is an important predator in coastal marine ecosystems of California, targeted by recreational and commercial fishermen and
of specific interest in fisheries management. From October 2003 to August 2006, 169 leopard sharks were collected from the
coast of California (between 40.750°N and 32.678°N) and analyzed for mitochondrial and nuclear genetic structure. Analyses
of mtDNA control region sequences revealed relatively low levels of genetic variation (five haplotypes, average pairwise divergence
π = 0.0067). In contrast, leopard sharks were highly polymorphic for inter simple sequence repeats (ISSRs), which characterize
a broad range of the nuclear genome. The null hypothesis of panmixia in California waters was rejected for both genetic markers,
and ISSRs displayed a statistically significant pattern of isolation by distance (IBD) across the species range (P = 0.002). A variety of analyses showed that divergence is most pronounced in the northernmost population of Humboldt Bay.
Natal philopatry in T. semifasciata was tested using Siegel-Tukey tests on data partitioned by breeding site status, and sex-specific philopatry was tested by
comparing IBD plots between sexes. Although there was some evidence for natal philopatry in leopard sharks (P = 0.038), and population divergence may be related to the proximity of breeding sites (P = 0.064), we found no support for sex-specific philopatry. In addition to identifying a novel set of highly variable genetic
markers for use in shark population studies, these results may be used to better inform management decisions for leopard sharks
in California. 相似文献
88.
Summary The vocal behavior of Hyla versicolor was studied in the field by means of behavioral observations and playback experiments, and these data were coupled with measurements of oxygen consumption in calling frogs to estimate the effect of social interactions on calling energetics. Male gray treefrogs have intense calls (median peak SPL=109 dB, fast RMS SPL=100 dB at 50 cm). At an air temperature of 23° C, males produced an average of 1,200–1,300 calls/h for 2–4 h per night. Calling rates and call durations differed among individuals, but were relatively constant for each male during periods of sustained calling. Males in dense choruses gave calls about twice as long as isolated males, but produced calls at about half the rate. Consequently, total calling effort and estimated aerobic costs were largely independent of chorus density. Playbacks of recorded calls to males in the field elicited increases in call duration and decreases in calling rate, regardless of the rate or duration of the stimulus. Males gave longer calls in response to long calls or to stimuli presented at high rates, but they did not precisely match either stimulus rate or duration. Calling effort and estimated oxygen consumption changed only slightly during stimulus playbacks. These results indicate that male-male competition elicits pro-found changes in the vocal behavior of calling males, but these changes have little effect on energy expenditure. We estimated that most calling males had metabolic rates of about 1.7–1.8 ml O2/(g\h), or about 280 J/h for an average size (8.6 g) male at 20° C. Although changes in call duration and calling rate did not affect aerobic costs of calling, males producing long calls at slow rates called for fewer hours per night than males producing shorter calls at higher rates. This suggests that calling time may be limited by the rate at which muscle glycogen reserves are depleted. 相似文献
89.
Although the genetic structure of many populations of marine organisms show little deviation from panmixia, in those marine species with limited larval dispersal, patterns of microgeographic genetic differentiation may be common. The octocoral Briareum asbestinum should show local population differentiation because colonies reproduce asexually by fragmentation, most matings occur between colonies in very close proximity, and the sexually produced larvae and sperm appear to disperse only short distances. Variability in secondary chemistry of individual B. asbestinum colonies from different populations in close proximity also suggests local population differentiation. We determined the genetic composition of local populations by surveying allozyme variation of three shallow and two deep populations within a 300 m2 area at San Salvador Island, Bahamas and at a site 161 km away on Little San Salvador, Bahamas in July 1990. As B. asbestinum occurs as either an erect branching form or an encrusting mat often at the same sites, we sampled both morphs to examine the extent of genetic exchange between them. Five of 21 loci were polymorphic and most populations showed a deficit of heterozygotes. Allele frequencies differed significantly between morphs at each site where they occurred together. The mean genetic distance (D=0.065) between morphs is consistent with the interpretation that the two morphs are genetically isolated. Despite the close spatial proximity of the San Salvador populations, both the branching and encrusting morphs showed significant genetic heterogeneity among neighboring populations. Similarly, pooled allelic frequencies for samples collected from the islands of San Salvador and Little San Salvador differed significantly at 1 locus for the branching morph and at 3 out of 5 loci for the encrusting morph. 相似文献
90.
F. Lynn Carpenter Mark A. Hixon Ethan J. Temeles Robert W. Russell David C. Paton 《Behavioral ecology and sociobiology》1993,33(5):305-312
Summary The three age-sex classes of rufous hummingbirds (Selasphorus rufus) that directly interact on southward migratory stopovers in our California study system differ in territorial ability and resource use. Immature males are behaviorally dominant to adult and immature females and defend the richest territories. Here, we test the hypothesis that the territorially subordinate age-sex classes compensate exploitatively for their exclusion from rich resources. Our results show that females were able to accumulate energy stores at rates comparable to males despite their subordinate territorial status. Territorial females gained body mass at the same rate and in the same pattern as males, and resumed migration at the same body masses. Moreover, during periods when birds were nonterritorial and used dispersed resources, adult and immature females maintained or gained body mass, whereas immature males lost mass. We suggest that females may be energetically compensated by (1) lower costs of flight incurred during foraging and defense, resulting from their lower wing disc loading, and (2) greater success at robbing nectar from rich male territories, resulting from duller coloration (immature females), experience (adult females), and, possibly, hormonal differences. In the future, experiments will be necessary to distinguish the various hypotheses about the mechanisms involved in compensation.
Correspondence to: F.L. Carpenter 相似文献