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1.
Motohiro Shimizu Muneharu Kusakari Mary M. Yoklavich George W. Boehlert Juro Yamada 《Environmental Biology of Fishes》1991,30(1-2):155-163
Synopsis Ultrastructural features of the epidermis and rectum were studied inSebastes schlegeli andS. melanops during the late stages of embryonic development, to confirm uptake of maternal substances. Ruthenium red (RR) and horseradish
peroxidase (HRP) were used at fixation and in live embryos, respectively. Epidermal tissue of embryos after developmental
stage 24 comprised two squamous cell layers. The outer, thinner cells and their intercellular spaces were easily infiltrated
with RR, but the inner cells had no RR deposition. The HRP was not incorporated into the epidermis except in a few outer cells,
which had well-developed microvillous projections of cytoplasm. Sacciform cells, chloride cells, and mucous cells distributed
in the inner layer but protruding to the epidermal surface had no intracellular RR and HRP depositions. The rectal cells of
embryos at about developmental stage 28 had many globular inclusions containing electron-dense substances. The rectal cells
were found to take up and digest HRP actively. It is suggested that the embryonic epidermis is structurally loose and takes
up low weight molecules, while rectal cells, after the opening of the mouth, actively ingest exogenous, high weight molecules. 相似文献
2.
Synopsis Pelagic larvae and juveniles of the genusSebastes are widely distributed in the continental shelf and slope waters of subarctic to temperate oceans, with greatest abundance
in the Northern Hemisphere. We review the ecology and distribution of these planktonic and micronektonic life stages in relation
to oceanographic conditions. Special attention is paid to the west coast of North America, where abundance of larvae from
samples collected during 1951–1981 is described. After transformation, the pelagic juveniles are widely distributed, often
at great distances from benthic adult habitats. These stages are most frequently distributed in either midwater or near-surface
habitats; this dichotomy may require different strategies for successful recruitment. 相似文献
3.
Synopsis The ability of embryos of the viviparous scorpaenidSebastes melanops to take up nutrients from an exogenous substrate was demonstrated by incubating embryos at various stages of development
(18–30 days after fertilization) in14C-labeled glycine for 24 h. Uptake was highest for embryos at the latest stages (28–30 days) and increased at a linear rate
during the incubation period. Nutrient uptake was not time dependent in embryos at the early stages (18–22 days). Nutrient
utilization byS. melanops embryos was measured by the oxidation of14C-labeled glycine to14CO2. The amount of respired14CO2 by the oldest embryos increased significantly at a linear rate over the 24 h incubation period. There was no evidence of
nutrient utilization by the youngest embryos. The developmental changes we observed in the uptake and utilization of exogenous
glycine are supported by our previous findings that the oldest embryos have fully developed mouths and guts, and require additional
nutrition from intraovarian sources at this stage of development. 相似文献
4.
Ralph J. Larson 《Environmental Biology of Fishes》1991,30(1-2):57-70
Synopsis Seasonal cycles of reserve deposition and utilization in many fishes, amphibians and reptiles alleviate temporal mismatches
of energy supply and demand. Utilization of reserves can be related to maintenance during periods of reduced food supply,
to reproduction, particularly during periods of poor food availability, and to migration. Published data on the seasonal cycles
of reserves and reproduction inSebastes suggest that reserves are important for maintenance during wintertime periods of low food availability. Unlike many other
ectothermic vertebrates, some species ofSebastes deposit fat reserves at the same time as gametogenesis, a pattern consistent with the longevity and iteroparity evident in
the genus. Other species ofSebastes have similar seasonal timing of fat cycles, but since reproduction takes place later in the year, the decline in reserves
during winter coincides with the main period of reproductive activity. The significance of this is not clear. Interspecific
differences in amounts of reserves may be related to geographical differences in the seasonality or abundance of food. Intraspecific
variation in reserves, marked most strongly by allometry of reserves with regard to fish legth, bears further study, since
it may link the proces of sexual maturation and the responses of repeat spawners to variability in food supply and other environmental
factors. 相似文献
5.
The reproductive modes of the Scorpaenidae are extremely varied: oviparity, viviparity, and even spawning of internally fertilized
eggs or embryos (zygoparity or embryoparity), as in Helicolenus, are known. The ovarian structure of this family is divided into two types by the arrangement of the stroma and the ovarian
cavity. One type is the ovary in which the lamella-like stroma develops from the ovarian hilus located on the dorsal side
and where the ovarian cavity is located on the ventral side of ovary, classified as “cystovarian type II-1” by Takano (1989).
In the other type, the stroma in the ovary develops radially around the blood circulatory system that traverses the center
of the ovary, and then the ovarian cavity surrounds all the ovary, classified as “cystovarian type II-3” by Takano (1989).
In the present analysis, previous reports about ovarian structure and the relationship to the reproductive mode of scorpaenids
were described, and the ovarian structure of eight genera of Scorpaenidae was examined. The ovary of cystovarian type II-1
is seen only in viviparous genera and is not seen in oviparous genera. However, the cystovarian type II-1 is a general structure
in other families of Scorpaeniformes, and this structure could be considered a primitive type of ovary rather than that acquired
by the process of evolution from oviparity to viviparity. The ovary of cystovarian type II-3 is seen in all six oviparous
genera and the one zygoparous genus examined. The ovary of this type is not found in any other family of teleosts, so it could
be a structure originally divided in Scorpaenidae. In the genera having the cystovarian type II-3 ovary, there is a common
feature of spawning: a floating egg mass encompassed by the gelatinous material. We postulate that the evolution of reproductive
mode in the scorpaenid fishes is as follows: Sebastes and Sebastiscus have a primitive ovary in which viviparity has developed, whereas the genera that spawn a floating egg mass evolved the ovarian
structure from primitive type to cystovarian type II-3, and further zygoparity, such as in Helicolenus, evolved from them. 相似文献
6.
Bruce M. Leaman 《Environmental Biology of Fishes》1991,30(1-2):253-271
Synopsis The characteristics of lightly and heavily exploited Pacific ocean perch,Sebastes alutus, stocks are evaluated relative to the predictions of life history theory. These long-lived species (50–100 year lifespan)
show limited phenotypic plasticity and have little buffering against the effects of reduced lifespan. Reduced stock abundance
has generated some compensatory increase in growth rate. Length at first maturity varies only slightly with increased growth
rate, although age at maturity may decrease by 1–4 years. Grooth increases yield larger (15–20%) size at age and increased
reproductive effort at younger ages, but lower size-specific fecundity for these faster-growing fish. This suggests an energy
allocation protocol favouring growth over reproduction in these long-lived animals. Rockfishes have late recruitment to fisheries
(ages 10–15), and the detection time for results of management actions is equally long. Their vulnerability to overfishing
means that indices of population changes, more representative of fishing effects than the catch rate index presently used,
are required. Reproductive value indices are shown to be extremely sensitive and continuous with population abundance changes.
Their incorporation into monitoring programs would permit more timely evaluation of management actions. Management policies
developed for shorter-lived species are shown to be inappropriate for rockfishes. The need for an improved match in the time
frame of the species' life history, and that of management strategies, is stressed. 相似文献
7.
John P. Wourms 《Environmental Biology of Fishes》1991,30(1-2):111-126
Synopsis Selected aspects of the reproduction and development ofSebastes and other rockfishes are reviewed in the context of piscine viviparity. Among the eight subfamilies of the Scorpaenidae,
viviparity is confined to the subfamily Sebastinae; gestation is lumenal and the embryos usually develop to term within the
egg envelope. Transitional states from oviparity to viviparity are evident in different species within the family. A scenario
for the evolutionary origin of viviparity in rockfishes is derived from an analysis of scorpaeniform reproductive biology.
Although viviparity is best developed in the genusSebastes, it is still in a primitive, unspecialized state. Rockfish viviparity is essentially lecithotrophic, i.e. embryonic nutrition
is dependent on the energy reserves laid down during oogenesis. In other groups of viviparous fishes, lecithotrophy has been
shown to be better suited energetically to seasonally unpredictable habitats, whereas matrotrophy requires a predictable food
supply. During the evolution of an essentially primitive form of lecithotrophic viviparity in rockfishes, the advantages of
high fecundity associated with oviparity were retained while an enormous increase in the survival rate of the developing embryos
was acquired. The basic lecithotrophic pattern of oviparous development was not changed since it offered selective advantages
both in terms of energetics and as a basis for retaining a large brood size. 相似文献
8.
Mayara De Carli Caroline Rech José Maurício Simões Bento Cristiane Nardi 《Revista Brasileira de Entomologia》2018,62(3):172-175
Diabrotica speciosa (Germar) and Diabrotica viridula F. (Coleoptera: Chrysomelidae) are the two most abundant species of the genus in South America, and belong to the fucata and virgifera groups, respectively. Here, we characterize the dimorphism of the setae present on the basitarsi of males and females of these species. Dimorphism was confirmed in both species, and it was related to the presence of adhesive setae exclusively in males, which possess these structures on the basal tarsomeres of the pro- and mesothoracic legs. 相似文献
9.
Tina Wyllie Echeverria 《Environmental Biology of Fishes》1986,15(3):181-190
Synopsis Sexual dimorphisms, and factors influencing the evolution of these differences, have been investigated for four species of
rockfish:Sebastes melanops, S. flavidus, S. mystinus, andS. serranoides. These four species, which have similar ecology, tend to aggregate by species with males and females staying together throughout
the year. In all four species adult females reach larger sizes than males, which probably relates to their role in reproduction.
The number of eggs produced increases with size, so that natural selection has favored larger females. It appears males were
subjected to different selective pressures than females. It was more advantageous for males to mature quickly, to become reproductive,
than to expend energy on growth. Other sexually dimorphic features include larger eyes in males of all four species and longer
pectoral fin rays in males of the three piscivorous species:S. melanops, S. flavidus, andS. serranoides. The larger pectoral fins may permit smaller males to coexist with females by increasing acceleration and, together with
the proportionately larger eye, enable the male to compete successfully with the female to capture elusive prey (the latter
not necessarily useful for the planktivoreS. mystinus). Since the size of the eye is equivalent in both sexes of the same age, visual perception should be comparable for both
sexes. 相似文献
10.
M. Pickford 《Human Evolution》1986,1(2):111-148
One of the more important sources of variability in primate species is sexual dimorphism. Most Primates heavier than five
kilos bodyweight are sexually dimorphic, both in body size and in shape of certain hard tissues. Despite these facts, most
of the fossil Primates from East African Miocene deposits were originally perceived as being monomorphic, a perception which
has propogated through the literature. Re-examination ofProconsul from various sites in Western Kenya results in the view that it was as dimorphic in its splanchonocranium and in bodyweight
as chimpanzees and gorillas. The clearest evidence comes from Rusing Island, where adequate samples are known of two morphs,
traditionally identified as two species, but more likely to represent two sexes of a single species,P. nyanzae. Co-occurrence of the two morphs is 100% at the various Rusinga sites. Less complete samples have been collected from the
Tinderet sites os Koru and Songhor, yet what is available shows that similar patterns of dimorphism characterise the speciesP. africanus andP. major, and that the co-occurrence of the two morphs in each species is 100%. The identification of fossils taking into consideration
the role of sexual dimorphism clarifies many of the old debates in which individual specimens frequently shifted between different
species, mainly on the basis of metric rather than morphologic evidence. Consequently, the distribution of the species ofProconsul is rather different after accounting for dimorphism, than it was before. 相似文献
11.
Leonard Owen Greenfield 《Primates; journal of primatology》1972,13(4):395-410
Among the numerous specimens presently classified withinDryopithecus africanus only one can be identified as a male of this species. Poor sampling is not the reason for the unequal numbers of male and female specimens. Rather, the males have been classified elsewhere, specifically withinDryopithecus nyanzae and Kenyapithecus africanus. The specimens to be transferred from these two taxa are proved to be males ofD. africanus. The newly transferred males are compared with the females to show the cranial dimorphism of the species. 相似文献
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14.
Sexual size dimorphism in anurans 总被引:4,自引:0,他引:4
Several hypotheses have been proposed to explain the direction and extent of sexual size dimorphism in anurans (in which males are usually smaller than females) as a result of sexual selection. Here, we present an analysis to test the hypothesis that sexual dimorphism in anurans is largely a function of differences between the sexes in life-history strategies. Morphological and demographic data for anurans were collected from the literature, and the mean size and age in each sex were calculated for 51 populations, across 30 species and eight genera. Comparisons across 14 Rana species, eight Bufo species and across the genera showed a highly significant relationship between size dimorphism, measured using the female-male size ratio, and mean female-male age difference. A comparison of a subset of 17 of these species for which phylogenetic information was available, using the method of independent contrasts, yielded a similar result. These results indicate that most of the variation in size dimorphism in the anura can be explained in terms of differences in the age structure between the sexes in breeding populations. If sexual selection has an effect on size dimorphism in anurans, it is likely to be only a secondary one. 相似文献
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17.
Sexual dimorphism in primate teeth 总被引:1,自引:0,他引:1
A new measure of sexual dimorphism in tooth size (Relative Male Tooth Size) is estimated for a sample of 39 primate species and is used to test predictions concerning the adaptive significance of sexual dimorphism in primate tooth size. It is concluded that both sexual selection and predator defence are important selective forces producing marked sexual dimorphism in the teeth used for fighting. 相似文献
18.
Sexual dimorphism in immune defense 总被引:8,自引:0,他引:8
ABSTRACT Sex differences in parasitism are common and may depend on sex differences in intensity of sexual competition, immunosuppression, or exposure to parasites. We used a large data set on the mass of two immune defense organs in birds (the bursa of Fabricius and the spleen) to test for consistent sex differences in immune defense. Males had a relative spleen mass that was consistently smaller, but more variable, than that of females across species of birds. A sex difference in the size of the spleen was not present among juveniles but was large and statistically significant among adults. The suppression of spleen mass in adult males increased with a measure of intensity of sexual selection: the frequency of extra-pair paternity. These findings suggest that sexdifferences in parasitism may arise as a consequence of sex differences in immune function, as mediated by sexual selection. 相似文献
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20.
Sexual size dimorphism in parasitoid wasps 总被引:1,自引:0,他引:1
Bethia Hurlbutt 《Biological journal of the Linnean Society. Linnean Society of London》1987,30(1):63-89
Sexual dimorphism in body length and proportion of overlap between the ranges of body length for males and females were estimated for 361 species of parasitoid wasps from 21 families. In most species, females are generally larger than males, though the range of male and female sizes overlap. Species in the family Ichneumonidae differ significantly from species in other families in three ways: (1) ichneumonids on average are larger, (2) in most species, females are generally smaller than males, and (3) on average, proportion overlap between the ranges of body length for males and females is greater. At present, there is a paucity of life history data on parasitoid wasp species for which size dimorphism is known. Thus it is not clear why ichneumonids differ from species in other families. Possible evolutionary explanations for variation in dimorphism among parasitoid wasp species are discussed. 相似文献