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1.
Antonella Soro Manfred Ayasse Marion U. Zobel Robert J. Paxton 《Behavioral ecology and sociobiology》2011,65(4):641-653
The ability to discriminate degrees of relatedness may be expected to evolve if it allows unreciprocated altruism to be preferentially
directed towards kin (Hamilton in J Theor Biol 7:1–16, 1964). We explored the possibility of kin recognition in the primitively eusocial halictid bee Lasioglossum malachurum by investigating the reliability of worker odour cues that can be perceived by workers to act as indicators of either nest
membership or kinship. Cuticular and Dufour’s gland compounds varied significantly among colonies of L. malachurum, providing the potential for nestmate discrimination. A significant, though weak, negative correlation between chemical distance
and genetic relatedness (r = −0.055, p < 0.001) suggests a genetic component to variation in cuticular bouquet, but odour cues were not informative enough to discriminate
between different degrees of relatedness within nests. This pattern of variation was similar for Dufour’s gland bouquets.
The presence of unrelated individuals within nests that are not chemically different from their nestmates suggests that the
discrimination system of L. malachurum is prone to acceptance errors. Compounds produced by colony members are likely combined to generate a gestalt colony chemical
signature such that all nestmates have a similar smell. The correlation between odour cues and nest membership was greater
for perceived compounds than for non-perceived compounds, suggesting that variability in perceived compounds is a result of
positive selection for nestmate recognition despite potentially stabilising selection to reduce variability in odour differences
and thereby to reduce costs derived from excessive intracolony nepotistic behaviour. 相似文献
2.
Kin-biased social tolerance among house mice has been interpreted in terms of kin discrimination. However, several lines of evidence suggest it may instead be an incidental artifact of group member discrimination. This leads to very different predictions about the social consequences of relatedness within and between social groups. Social interactions between wild-stock adult female and juvenile house mice (Mus domesticus) established in neighbouring territorial groups within enclosures reveal relatedness to dominant males within groups as the major factor determining social tolerance of juveniles by females. Relatedness to the female herself had no significant independent effect on responses indicating tolerance. Females were generally more aggressive toward neighbouring-group juveniles (all unrelated to females) compared with those from their own group (all related to females), but were most aggressive toward neighbouring juveniles sired by the neighbouring dominant male. They were also more aggressive toward their own-group juveniles that had been sired by the neighbouring dominant but only when encountered in the neighbouring territory and with a greater bias against female juveniles. Females were least aggressive toward own-group juveniles sired by their own-group dominant male. The sire-bias in tolerance among females is similar to that reported among the dominant males themselves in an earlier study. As a result of the combined sire-bias in tolerance by adult males and females, juveniles sired by their own-group dominant males become less likely to intrude into a neighbouring territory with time. Overall, the results suggest that differences in social tolerance reflect discrimination on the basis of social group membership rather than relatedness between interactants and thus provide strong experimental evidence in support of incidental kin bias rather than kin discrimination. 相似文献
3.
In populations of various ant species, many queens reproduce in the same nest (polygyny), and colony boundaries appear to
be absent with individuals able to move freely between nests (unicoloniality). Such societies depart strongly from a simple
family structure and pose a potential challenge to kin selection theory, because high queen number coupled with unrestricted
gene flow among nests should result in levels of relatedness among nestmates close to zero. This study investigated the breeding
system and genetic structure of a highly polygynous and largely unicolonial population of the wood ant Formica paralugubris. A microsatellite analysis revealed that nestmate workers, reproductive queens and reproductive males (the queens' mates)
are all equally related to each other, with relatedness estimates centring around 0.14. This suggests that most of the queens
and males reproducing in the study population had mated within or close to their natal nest, and that the queens did not disperse
far after mating. We developed a theoretical model to investigate how the breeding system affects the relatedness structure
of polygynous colonies. By combining the model and our empirical data, it was estimated that about 99.8% of the reproducing
queens and males originated from within the nest, or from a nearby nest. This high rate of local mating and the rarity of
long-distance dispersal maintain significant relatedness among nestmates, and contrast with the common view that unicoloniality
is coupled with unrestricted gene flow among nests.
Received: 8 February 1999 / Received in revised form: 15 June 1999 / Accepted: 19 June 1999 相似文献
4.
Growth and development rates were determined for nauplii of Calanus finmarchicus (Gunnerus) in the near-shore waters of a western Norwegian fjord from in situ mesocosm incubations. The major food source
for the nauplii was diatoms, but Phaeocystis sp., dinoflagellates and ciliates were also part of the diet. At local temperatures ranging from 4.8 to 5.2 °C the cumulative
median development time from hatching to Nauplius VI was 19 d. The time taken to molt to the next naupliar stage was approximately
constant (3 d) from Stages IV to VI, but Stage III needed the longest development time (5 d). The instantaneous growth rate
in terms of body carbon was negative from hatching to Nauplius Stage II, but as high as 0.25 to 0.30 d−1 from Stage III to V. Enhancement of food resources by nutrient addition led to no significant change in specific growth rates.
Additionally, the cohorts from different nutrient regimes showed almost equal development time, size and body carbon within
stages. Length–weight relationships of nauplii from the two different food resources were: W
low resources = 4.17 × 10−6 × L
2.03 (r
2 = 0.84) and W
high resources = 4.29 × 10−6 × L
2.05 (r
2 = 0.92), where weight (W) is in micrograms of C and body length (L) in micrometers. The natural body morphology of naupliar stages I to VI is illustrated with digital images, including the
final molt from Nauplius VI to Copepodid Stage I. In general, development of the nauplii was faster than that of the copepodids
of C. finmarchicus, and structural growth was exponential from naupliar stages III to VI. This study validates our earlier results that nauplii
of C. finmarchicus can obtain high growth and nearly maximal developmental rates at relatively low food levels (∼50 μg C l−1), suggesting that nauplii exhibit far less dependence on food supply than copepodids.
Received: 30 July 1999 / Accepted: 7 March 2000 相似文献
5.
Kinship and aggression: do house sparrows spare their relatives? 总被引:1,自引:0,他引:1
Zoltán Tóth Veronika Bókony Ádám Z. Lendvai Krisztián Szabó Zsolt Pénzes András Liker 《Behavioral ecology and sociobiology》2009,63(8):1189-1196
Kin-selection theory predicts that relatedness may reduce the level of aggression among competing group members, leading to
indirect fitness benefits for kin-favoring individuals. To test this hypothesis, we investigated whether relatedness affects
aggressive behavior during social activities in captive house sparrow (Passer domesticus) flocks. We found that sparrows did not reduce their aggression towards kin, as neither the frequency nor the intensity of
fights differed between close kin and unrelated flock-mates. Fighting success was also unrelated to kinship and the presence
of relatives in the flock did not influence the birds’ dominance rank. These results suggest that the pay-offs of reduced
aggression towards kin may be low in non-breeding flocks of sparrows, e.g. due to competition among relatives as predicted
by a recent refinement of kin-selection theory. Our findings indicate that the significance of kin selection may be restricted
in some social systems such as winter aggregations of birds.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Historically, most mammals have been classified as polygynous; although recent molecular evidence suggests that many mammals
may be polygynandrous, particularly the ground-dwelling sciurids. We genotyped 351 round-tailed ground squirrels (Xerospermophilus tereticaudus) using seven microsatellite loci to determine paternity in 31 litters from 2004 to 2007. Polygyny was evident in all years
except in 2007, when the population size was reduced. Multiple paternity occurred in the majority of litters (55%) with 2.5 ± 0.26
sires/litter (n = 31). Forty-nine percent of resident males (n = 114) sired offspring, and of males that sired offspring (n = 56) 27% sired young in multiple litters in a single breeding season. Litter size was positively correlated with the number
of sires. Through an indirect analysis of paternity, we found 21 litters (68%) with an average relatedness of 0.5 or less.
Males had a greater opportunity for sexual selection (I
s = 1.60) than females (I
s = 0.40); Bateman’s gradient was also greater in males (1.07 ± 0.04, n = 56) than females (0.82 ± 0.08, n = 31). The mating system in round-tailed ground squirrels defined through genetic analyses and Bateman’s gradients is polygynandrous
compared to the previously suggested polygynous mating system as established by behavioral observations and fits within the
predictions of the ground squirrel sociality models. Upon evaluating the predictions of the sociality models among sciurid
species, we found a negative relationship between the level of sociality with litter size and the average percentage of multiple
paternity within a litter. Thus, recent genetic information and reclassification of mating systems support the predictions
of the ground-dwelling squirrel sociality models. 相似文献
7.
Christine R. Maher 《Behavioral ecology and sociobiology》2009,63(6):857-868
Solitary species show several patterns of space use and relatedness. Individuals may associate randomly or may live near female
or male kin, often as a result of natal philopatry or dispersal patterns. Although usually described as solitary or asocial,
woodchucks (Marmota monax) are behaviorally flexible marmots that exhibit greater sociality in some populations than others. I examined relationships
between kinship, geographic distance, and home range overlap, as well as dispersal and philopatry, to determine the extent
to which kin associated spatially. I used a combination of microsatellite DNA analysis, long-term behavioral observations,
and radiotelemetry to test predictions that females, but not males, would associate with kin. Indeed, woodchucks lived closer
and shared a greater proportion of their home range with more closely related animals. Overlap of females' and males' home
ranges was positively correlated with kinship, and male–female dyads shared more area with closer kin. Most juveniles delayed
dispersal beyond their first summer. Females often remained philopatric and settled near their natal range. Although males
often dispersed as yearlings, some males also established territories within or immediately adjacent to their natal home ranges.
A combination of factors can explain these spatial patterns, including high population density associated with the study site's
location within a suburban environment, high dispersal costs, and abundant food. Thus, despite their asocial and solitary
reputation, woodchucks displayed spatial patterns seen in other, more social species of ground-dwelling sciurids. 相似文献
8.
High relatedness and inbreeding in two species of haplodiploid eusocial thrips (Insecta: Thysanoptera) revealed by microsatellite analysis 总被引:1,自引:0,他引:1
Relatedness and inbreeding coefficients were estimated for Oncothrips tepperi and O. habrus, two species of eusocial gall-forming thrips, using data from two microsatellite loci. Relatedness between sets of individuals
(sexes and castes) for O. tepperi ranged from 0.5 to 0.85 and for O. habrus estimates were centered around 0.5. Multiple mating in O. habrus was implicated in lowering relatedness within a gall. We estimated the inbreeding coefficient to be 0.38 for both species,
the highest estimates known for eusocial insects. Our findings imply that high relatedness and inbreeding are important for
the evolution and form of social behavior in Australian gall-forming Thysanoptera.
Received: 14 November 1997 / Accepted after revision: 14 March 1998 相似文献
9.
The growth rates of two fish species, the winter flounder Pseudopleuronectes americanus (Walbaum) (19.3 to 42.6 mm total length, TL) and the tautog Tautogaonitis (Linnaeus) (23.9 to 55.9 mm TL), were used to evaluate habitat quality under and around municipal piers in the Hudson River
estuary, USA. Growth rates were measured in a series of 10 d field caging-experiments conducted at two large piers in the
summers of 1996 and 1997. Cages (0.64 m2) were deployed along␣transects that stretched from underneath the piers to beyond them, encompassing the pier edge (the transitional
zone between the pier interior and the outside). Growth in weight (G
w
) was determined at five locations along the transect, 40 m beneath the pier, 20 m beneath the pier, at the pier edge, 20 m
beyond the pier edge, and 40 m beyond. Under piers, mean growth rates of winter flounder and tautogs were negative (xˉG
W
= −0.02 d−1), and rates were comparable to laboratory-starved control fishes (xˉG
W
= −0.02 d−1). In contrast, mean growth rates at pier edges and in open waters beyond piers were generally positive (xˉG
W
ranged from −0.001 to +0.05 d−1), with growth at pier edges often being more variable and less rapid than at open-water sites. Analyses of stomach contents
upon retrieval of caged fishes revealed that dry weights of food were generally higher among fishes caged at open-water stations
(xˉ range = 0.02 to 0.72 mg dry wt) than at pier-edge (xˉ range = 0.01 to 0.54 mg) or under-pier (xˉ range = 0.03 to 0.11 mg) stations, although it was apparent that benthic prey were available at all stations on the transect.
Our results indicate poor feeding conditions among fishes caged under piers, and suboptimal foraging among fishes caged at
pier edges. Inadequate growth rates can lead to higher rates of mortality, and, based on these and other earlier experiments,
we conclude that under-pier environments are poor-quality habitats for some species of juvenile fishes.
Received: 12 March 1998 / Accepted: 9 November 1998 相似文献
10.
Knowledge of the sociogenetic organization determining the kin structure of social insect colonies is the basis for understanding
the evolution of insect sociality. Kin structure is determined by the number and relatedness of queens and males reproducing
in the colonies, and partitioning of reproduction among them. This study shows extreme flexibility in these traits in the
facultatively polygynous red ant Myrmica rubra. Relatedness among worker nestmates varied from 0 to 0.82. The most important reason for this variation was the extensive
variation in the queen number among populations. Most populations were moderately or highly polygynous resulting in low relatedness
among worker nestmates, but effectively monogynous populations were also found. Polygynous populations also often tend to
be polydomous, which is another reason for low relatedness. Coexisting queens were positively related in two populations out
of five and relatedness was usually similar among workers in the same colonies. Due to the polydomous colony organization
and short life span of queens, it was not possible to conclusively determine the importance of unequal reproduction among
coexisting queens, but it did not seem to be important in determining the relatedness among worker nestmates. The estimates
of the mating frequency by queens remained ambiguous, which may be due to variation among populations. In some populations
relatedness among worker nestmates was high, suggesting monogyny and single mating by queens, but in single-queen laboratory
nests relatedness among the worker offspring was lower, suggesting that multiple mating was common. The data on males were
sparse, but indicated sperm precedence and no relatedness among males breeding in the same colony. A comparison of social
organizations and habitat requirements of M. rubra and closely related M. ruginodis suggested that habitat longevity and patchiness may be important ecological factors promoting polygyny in Myrmica.
Received: 15 May 1995/Accepted after revision: 17 October 1995 相似文献
11.
Robert L. Curry 《Behavioral ecology and sociobiology》1988,22(2):141-152
Summary The social organization of the Galápagos mockingbird (Nesomimus parvulus) in unusual in that groups frequently include more than one breeding pair (plural breeding), and helping behavior is flexible: some birds neither breed nor help, while others do both. To investigate the influence of kinship on helping behavior, I categorized each bird as a helper or non-helper with respect to each nest within its group where it had an opportunity to help. The incidence of helping varied with relatedness: more birds helped when nestlings available to be fed were close relatives than when not. This result was independent of a higher incidence of helping among males than among females and of variation with age among males. Proportionally more nonbreeding than breeding males helped, but breeding and nonbreeding females helped equally infrequently; breeders helped most often after their own nests failed. The incidence of helping was highest among birds with opportunities to feed offspring of breeders that had fed the potential helper as a nestling, suggesting a mechanism for kin discrimination based on associative learning. Juveniles with opportunities to choose among alternative recipients preferentially fed closely related nestlings, but insufficient information was available to determine if adults also did so. Kinship did not influence the rate at which nestlings were fed by helpers. Juveniles fed nestlings at lower rates than did adult helpers, but helping effort was otherwise unaffected by age, sex, or relatedness. Limitation of help to former feeders functions as a mechanism for directing aid to relatives in a plural breeding system where degrees of kinship vary among potential recipients within the same group. 相似文献
12.
The relative roles of kinship and familiarity in affecting an individual’s growth and fitness are not easy to disentangle.
Not only is an individual more likely to have prior behavioral interactions with conspecifics in close proximity, it may also
be related (in terms of kinship) to those nearby conspecifics. While some studies have inferred that kin discrimination affects
fitness correlates, other studies found that familiarity alone can reduce aggressive interactions, thus increasing fitness.
These studies have all focused on intra-age class pairs or groups. However, many animals interact with conspecifics from different
cohorts. In many populations, adults of Plethodon cinereus territorially defend rocks and logs that retain moisture and food resources. We investigated whether juveniles of P. cinereus grew more in the presence of adults that were relatives or familiar. We collected pairs of juveniles and adults found under
the same cover objects in the forest (familiar) and pairs of juveniles and adults found under different cover objects, approximately
10 m apart (unfamiliar). We determined parentage and relatedness of the adult–juvenile pairs and then placed these pairs in
semi-natural mesocosms for 17 days. We found that juveniles housed with familiar adults had significantly greater increases
in mass and snout–vent length than juveniles housed with unfamiliar adults in 2006 but not in 2007. Relatedness had no effect
on growth. In addition, juveniles cohabitating with adults were not more likely to be their offspring. At least under certain
environmental conditions, familiarity with adults, independent of relatedness or parentage, increased the growth of juvenile
salamanders. 相似文献
13.
John L. Hoogland 《Behavioral ecology and sociobiology》2009,63(11):1621-1634
From 1995 through 2005, I studied nursing among Utah prairie dogs (Cynomys parvidens) living under natural conditions at Bryce Canyon National Park, UT, USA. I observed 850 aboveground nursings, which involved
122 mothers and 248 juveniles from 134 litters. Most of the mothers that nursed aboveground were middle-aged, and most nursing
juveniles had been coming aboveground for 1–3 weeks. Most nursings involved a single juvenile, lasted 1–10 min, and occurred
between 1800 hours and 2000 hours. Seventy-five percent of nursings (598/796) involved a mother suckling her own juvenile
offspring; the other 24.9% (198/796) involved a mother suckling another mother’s offspring (i.e., communal nursing). Communal
nursings involved juveniles of the home territory, and many communal nursings (74/198 = 37.4%) involved close kin such as
half-siblings, grandoffspring, full-nieces, and full-nephews; other communal nursings (37/198 = 18.7%) involved more distant
kin such as full-second cousins and full-third cousins. Of seven hypotheses that might explain the evolution of communal nursing,
evidence supports the importance of two: elevated inclusive fitness via indirect selection and communal nursing as a cost
of coloniality. 相似文献
14.
Nutrients were added separately and combined to an initial concentration of 10 μM (ammonium) and/or 2 μM (phosphate) in a series of experiments carried out with the giant clam Tridacna maxima at 12 microatolls in One Tree Island lagoon, Great Barrier Reef, Australia (ENCORE Project). These nutrient concentrations
remained for 2 to 3 h before returning to natural levels. The additions were made every low tide (twice per day) over 13 and
12 mo periods for the first and second phase of the experiment, respectively. The nutrients did not change the wet tissue
weight of the clams, host C:N ratio, protein content of the mantle, calcification rates or growth rates. However, ammonium
(N) enrichment alone significantly increased the total population density of the algal symbiont (Symbiodinium sp.: C = 3.6 · 108 cell clam−1, N = 6.6 · 108 cell clam−1, P = 5.7 · 108 cell clam−1, N + P = 5.7 · 108 cell clam−1; and C = 4.1 · 108 cell clam−1, N = 5.1 · 108 cell clam−1, P = 4.7 · 108 cell clam−1, N + P = 4.5 · 108 cell clam−1, at the end of the first and second phases of the experiment, respectively), although no differences in the mitotic index
of these populations were detected. The total chlorophyll a (chl a) content per clam but not chlorophyll a per cell also increased with ammonium addition (C = 7.0 mg chl a clam−1, N = 13.1 mg chl a clam−1, P = 12.9 mg chl a clam−1, N + P = 11.8 mg chl a clam−1; and C = 8.8 mg chl a clam−1, N = 12.8 mg chl a clam−1; P = 11.2 mg chl a clam−1, N + P = 11.3 mg chl a clam−1, at the end of the first and second phases of the experiment, respectively). The response of clams to nutrient enrichment
was quantitatively small, but indicated that small changes in inorganic nutrient levels affect the clam–zooxanthellae association.
Received: 2 June 1997 / Accepted: 9 June 1997 相似文献
15.
K. A. Tricklebank 《Marine Biology》2000,136(2):337-348
Parma microlepis (Günther) were collected from Malabar, an urban location close to the centre of Sydney, Australia, and from Jervis Bay, a
reference location 170 km south of the city centre. At each location, fish were collected from two sites separated by 100
to 200 m. The ultrastructure of normal liver tissue is described based on 20 female fish collected from Jervis Bay, where
fish are known to be exposed to low levels of organochlorine contaminants. Alterations in the endoplasmic reticulum, mitochondria,
lysosomes and nuclei of hepatocytes were identified and quantified in the liver tissue of fish from this location and compared
to alterations in 20 female fish collected from Malabar, where fish are exposed to higher concentrations of organochlorine
pesticides such as DDT compounds. There were significant differences in the percentage of hepatocytes with swollen mitochondria
(F = 124.025, df = 2, 2, P = 0.008) and atypical nuclei (F = 22.198, df = 2, 2, P = 0.043) between sites (100 to 200 m apart), but there were no clear differences between the percentage of structural alterations
in the hepatocytes of P. microlepis from Jervis Bay and Malabar. Associations between liver morphology and the organochlorines aldrin, dieldrin, DDE and chlordane
were examined using a Pearson correlation matrix. Significant correlations were detected between the percentage of hepatocytes
with dilated endoplasmic reticulum and the concentrations of the pesticide aldrin (r = 0.600, df = 11, r
crit(α = 0.05) = 0.553). Significant associations were also detected between the percentage of hepatocytes with disorganised endoplasmic
reticulum and the concentrations of dieldrin and DDE residues in fish (r = 0.576, r = 0.567, respectively, df = 13, r
crit (α = 0.05) = 0.514). However, there was little evidence that ultrastructural alterations in fish responded to increasing concentrations
of these pesticides in a consistent dose-response manner.
Received: 20 October 1998 / Accepted: 24 November 1999 相似文献
16.
We manipulated availability of food and nesting sites in one population of the forest ant Myrmica punctiventris. The manipulations produced significant changes in relatedness structure, reproductive allocation, and response to hierarchical
selection. Food availability appeared to have a consistently stronger influence on these aspects of social organization than
did availability of nesting sites. We interpret our experimental results in light of observed differences between populations,
and discuss implications for kin selection dynamics.
Received: 30 July 1998 / Accepted after revision: 31 October 1998 相似文献
17.
A. A. Keller C. Taylor C. Oviatt T. Dorrington G. Holcombe L. Reed 《Marine Biology》2001,138(5):1051-1062
The seasonal productivity cycle and factors controlling annual variation in the timing and magnitude of the winter–spring
bloom were examined for several locations (range: 42°20.35′–42°26.63′N; 70°44.19′–70°56.52′W) in Boston Harbor and Massachusetts
Bay, USA, from 1995 to 1999, and compared with earlier published data (1992–1994). Primary productivity (mg C m−2 day−1) in Massachusetts Bay from 1995 to 1999 was generally characterized by a well-developed winter–spring bloom of several weeks
duration, high but variable production during the summer, and a prominent fall bloom. The bulk of production (mg C m−3 day−1) typically occurred in the upper 15 m of the water column. At a nearby Boston Harbor station a gradual pattern of increasing
areal production from winter through summer was more typical, with the bulk of production restricted to the upper 5 m. Annual
productivity in Massachusetts Bay and Boston Harbor ranged from a low of 160 g C m−2 year−1 to a high of 787 g C m−2 year−1 from 1992 to 1999. Mean annual productivity was higher (mean=525 g C m−2 year−1) and more variable near the harbor entrance than in western Massachusetts Bay. At the harbor station productivity varied
more than 3.5-fold (CV=40%) over an 8 year sampling period. Average annual productivity (305–419 g C m−2 year−1) and variability around the means (CV=25–27%) were lower at both the outer nearfield and central nearfield regions of Massachusetts
Bay. Annual productivity in 1998 was unusually low at all three sites (<220 g C m−2 year−1) due to the absence of a winter–spring phytoplankton bloom. Potential factors influencing the occurrence of a spring bloom
were investigated. Incident irradiance during the winter–spring period was not significantly different (P > 0.05) among years (1995–1999). The mean photic depth during the bloom period was significantly deeper (P < 0.05) in 1998, signifying greater light availability with depth. Nutrients were also in abundance during the winter–spring
of 1998 with stratified conditions not observed until May. In general, the magnitude of the winter–spring bloom in Massachusetts
Bay from 1995 to 1999 was significantly correlated with winter water temperature (r
2=0.78) and zooplankton abundance (r
2=0.74) over the bloom period (typically February–April). The absence of the 1998 bloom was associated with higher than average
water temperature and elevated levels of zooplankton abundance just prior to, and during, the peak winter–spring bloom period.
Received: 3 July 2000 / Accepted: 6 December 2000 相似文献
18.
All other things being equal, the lifetime reproductive success (LRS) of iteroparous and semelparous individuals should scale
with the number of breeding seasons. Deviations from this relationship may occur for many reasons, including age- or size-related
fecundity or life history trade-offs, which may differ between sexes. We used 19 brood years of DNA parentage analysis in
a small (N = 4–143 year−1) wild, unexploited population of steelhead trout (Oncorhynchus mykiss) to compare the LRS of individuals that spawned only once [“one time spawners” (OTS), N = 355 male, 371 female] to those spawning twice [“repeat spawners” (RPS), N = 13 male, 49 female]. Female RPS had nearly twice the LRS of female OTS (1.17 offspring per female vs 0.91 offspring per
female), whereas male RPS had nearly three times the LRS of male OTS (1.54 offspring per male vs 0.57 offspring per male).
Female RPS produced slightly more adult offspring during their second breeding season than their first (0.78 vs 0.82 offspring
per female); however, male RPS produced all of their adult offspring in their second breeding season (0 vs 1.54 offspring
per male). The additional growth in body size of males between breeding seasons may give them an advantage in their second
breeding season, but the lack of offspring produced in their first season suggests a trade-off between survival and future
reproduction that was not expressed in females. 相似文献
19.
Zooplankton responses to hypoxia: behavioral patterns and survival of three species of calanoid copepods 总被引:2,自引:0,他引:2
Seasonally recurrent and persistent hypoxic events in semi-enclosed coastal waters are characterized by bottom-water dissolved
oxygen (d.o.) concentrations of < 2.0 ml l−1. Shifts in the distribution patterns of zooplankters in association with these events have been documented, but the mechanisms
responsible for these shifts have not been investigated. This study assessed interspecific differences in responses to hypoxia
by several species of calanoid copepods common off Turkey Point, Florida, USA: Labidocera aestiva (Wheeler) (a summer/fall species), Acartia tonsa (Dana) (a ubiquitous year-round species), and Centropages hamatus (Lilljeborg) (a winter/spring species). Under conditions of moderate to severe hypoxia 24-h survival experiments were conducted
for adults and nauplii of these species from August 1994 to October 1995. Experiments on adults used a flow-through system
to maintain constant d.o. concentrations. Adults of A. tonsa showed no decline in survival with d.o. as low as 1.0 ml l−1, sharp declines in survival at d.o. = 0.9 to 0.6 ml l−1, and 100% mortality with d.o. = 0.5 ml l−1. Adults of L. aestiva and C. hamatus were more sensitive to oxygen depletion: both species experienced significant decreases in survival for d.o. = 1.0 ml l−1. Nauplii of L. aestiva and A. tonsa showed no significant mortality with d.o. = 1.1 to 1.5 ml␣l−1 and d.o. = 0.24 to 0.5 ml l−1, respectively. In addition, experiments investigating behavioral avoidance of moderate to severe hypoxia were carried out
for adults of all three species. None of the three species effectively avoided either severely hypoxic (d.o. < 0.5 ml l−1) or moderately hypoxic (d.o. ≈ 1.0 ml l−1) bottom layers in stratified columns. These results suggest that in␣nearshore areas where development of zones of d.o. < 1.0 ml
l−1 may be sudden, widespread, or unpredictable, patterns of reduced copepod abundance in bottom waters may be due primarily
to mortality rather than avoidance.
Received: 31 August 1996 / Accepted: 24 September 1996 相似文献
20.
Determination of basic population parameters in long-lived Crustacea is hindered by a lack of appropriate methods for age
determination. This study uses the pigment lipofuscin as an age marker in the common Antarctic decapod Notocrangon antarcticus (Pfeffer, 1887) from the eastern Weddell Sea. Resin brain sections of the lateral somacluster of the olfactory lobe of 189
specimens were digitally recorded by confocal microscopy and images were subsequently analyzed. A modal progression analysis
of the lipofuscin concentration–frequency distribution revealed a total of eight regularly spaced modes presumed to reflect
consecutive annual age classes. All eight modes contained females, and the first four contained males. No regular modes were
obvious in the comparable length-frequency distribution. The average yearly pigment accumulation was nearly linear and estimated
as 0.02% area fraction year−1, which is considerably lower than rates published for species from lower latitudes. This is probably explained by the effect
of low water temperature on metabolism and lipofuscin accumulation rate. The growth parameters CL∞ and k from the von Bertalanffy growth function were 22.3 mm and 0.79 year−1 for females, respectively, and 16.9 mm and 0.64 year−1 for males, respectively. Mortality, estimated from catch curves, amounted to 0.44 year−1 in females and 0.92 year−1 in males, whereas P/B, calculated from the mass specific growth rate method, was slightly lower. The results indicate that the lipofuscin-inferred
population parameters are an improvement over what can be learned about N. antarcticus with traditional methods.
Received: 1 August 2000 / Accepted: 21 September 2000 相似文献