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1.
The male secondary sex characters of Jaera albifrons
Leach, Jaera ischiosetosa
Forsman, Jaera praehirsuta
Forsman and Jaera forsmani
Bocquet are described with the Stereoscan electron microscope (S.E.M.). These characters, which are present on the peraeopods, are the only means of identification for these Jaera species which together form the Jaera albifrons group (Isopoda, Asellota). The male praeoperculum (modified, fused, first pair of pleopods) and appendix masculinae (modified endites of the second pair of pleopods) have also been studied with the S.E.M. and possible functions of the various sex characters are discussed. Both the male operculum and appendix masculinae are similar for each species, suggesting that copulation with females of a different species is anatomically possible. The fact that hybrids are rarely collected in ecological investigations is discussed with reference to the present known information. Two methods of copulation for the members of this group have been proposed and these are discussed. A method of sperm transfer along the male operculum is outlined. 相似文献
2.
M. Thiel 《Marine Biology》2000,137(4):661-674
The population dynamics and reproductive biology of an ascidian- and a sponge-dwelling amphipod were examined. The two undescribed
amphipod species, Leucothoe“ascidicola” and L.“spongicola”, are closely related to each other, and occur in ascidians and sponges, respectively, along the Florida Atlantic coast.
L. “ascidicola” was abundant in solitary ascidians during fall 1997, disappeared during spring/early summer, and became abundant again in
September 1998. During the time when L. “ascidicola” were absent from their hosts, a copepod became a frequent inhabitant of the ascidians but disappeared again when L.“ascidicola” returned to the ascidians in September 1998. The numbers of L.“spongicola” in sponges increased substantially during spring, when high reproductive activity was observed. Following this reproductive
peak, both adult and juvenile amphipods apparently left the sponges, and during the summer amphipod numbers in the sponges
were very low. Another small amphipod species, which often co-occurred with L.“spongicola”, showed less seasonal variation and was found in sponges throughout the whole study period. The percentage of ovigerous
females per host unit was usually lower in the ascidian-dwelling than in the sponge-dwelling amphipods. In solitary ascidians,
L.“ascidicola” amphipods usually occurred in groups of several adults, yet there never was more than one ovigerous female per ascidian.
In contrast, several ovigerous L.“spongicola” females were found to cohabit in the same spongocoel. This suggests that intrasexual aggression may be stronger among reproductive
amphipod females in the ascidians than in sponges. The size distributions of juvenile cohorts indicate that juvenile L.“ascidicola” remain for relatively long time periods in the parental ascidian, where they may reach sexual maturity. In contrast, in
L.“spongicola”, only cohorts of very small juveniles could be identified, indicating that juveniles disperse shortly after emerging from
the female's brood pouch. It is concluded that extended parental care is of very short duration or does not occur in the sponge-dwelling
amphipod L. “spongicola”, possibly because fast-growing sponges with a highly branched spongocoel system do not allow long-lasting coexistence of
parent-offspring groups. In contrast, the discrete character of the solitary ascidians may enhance the potential for exclusion
of other species, resource monopolization by reproductive females, and furthermore for long-lasting extended parental care
in the ascidian-dwelling amphipod. Groups of single parents together with cohorts of large juveniles are reported in the literature
for amphipods and isopods from brachiopods, bivalves and ascidians, suggesting that these discrete biotic microhabitats may
favor the evolution of extended parental care in peracarid crustaceans.
Received: 30 July 1999 / Accepted: 8 May 2000 相似文献
3.
Physiological studies were made on the crabs Ucides cordatus (L.) and Callinectes danae sampled from populations living in “polluted” mangroves on the southeast littoral of Brazil. Analysis of Cu, Cd, Zn, and
Fe of sediments and crab tissues showed interspecific differences in tissue concentrations, and significantly higher levels
of Cu, Cd, and Zn in “polluted” populations compared to “unpolluted” crabs living in uncontaminated mangrove in the same geographical
area. Individuals of both species from the polluted site showed significantly greater capacities for regulating blood osmotic
concentrations at low salinity (9‰). However, U. cordatus showed a reduced hypo-regulatory ability in 34‰S. Differences in ionoregulation were also seen. “Polluted”C. danae showed significantly higher Na/ K-ATPase levels in posterior gills compared to “unpolluted” crabs. Oxygen consumption rates
(M˙
O2) were elevated in U. cordatus, but depressed in C. danae from the “polluted” population. Individuals of both species from this site showed significantly lower O:N ratios, mainly
because of an increased net efflux of ammonia. Adenylate energy charge (AEC) values of muscle and hepatopancreas in “unpolluted”
and “polluted” populations of both species were not significantly different. These physiological differences are discussed
in relation to the known acute physiological and metabolic effects of heavy metals in crustaceans, and interpretated in the
light of possible adaptive changes following long-term exposure to contamination.
Received: 6 August 1999 / Accepted: 22 June 2000 相似文献
4.
Julia Bartmess-LeVasseur Carrie L. Branch Sheri A. Browning Jessica L. Owens Todd M. Freeberg 《Behavioral ecology and sociobiology》2010,64(7):1187-1198
Evidence from different chickadee species (Poecile genus) indicates that birds can modify the note composition of their “chick-a-dee” calls in the presence of predator stimuli.
Here, we tested the effects of predator models and the distance of those models on calls of three species foraging together
at feeding stations: Carolina chickadees (Poecile carolinensis) and tufted titmice (Baeolophus bicolor), both members of the Paridae family, and white-breasted nuthatches (Sitta carolinensis), a member of the Sittidae family. Model and distance affected seed-taking rates in all three species. “Chick-a-dee” calling
rates were higher in the predator context for both chickadees and titmice, but we detected no predator context effects on
“quank” call rates for nuthatches. Predator and distance contexts affected acoustic parameters of notes of the “chick-a-dee”
calls of chickadees and titmice; no such effects were detected for nuthatch “quank” calls. These results suggest species differences
in encoding of information in the primary social calls of these three species that commonly occur in multi-species flocks.
Chickadees and titmice are “nuclear” species and nuthatches are “satellite” species, and these different roles might be related
to the differences in vocal signaling that we detected. 相似文献
5.
Like many other benthic infaunal invertebrates, spionid polychaetes often lose portions of their bodies to predators, which
affects their activities. Feeding palp loss and tail loss have been studied in several spionids, but the capacity for anterior
tissue regeneration has not been compared in different species. The present study examines anterior tissue regeneration in
two species, Dipolydora quadrilobata (Jacobi 1883) and Pygospio elegans Claparède 1863, in two laboratory experiments. Tissue removal treatments included removal of palps only, removal of anterior
tissue through the first setiger, anterior tissue through the fifth setiger, all anterior tissue through half of the gill-bearing
setigers, and all anterior tissue through the last gill-bearing setiger. Regeneration was monitored by capturing images of
the worms and digitizing the area of regenerated anterior tissue or counting the number of segments that grew over time. Worms
of both species regenerated anterior tissue regardless of the amount removed. Morphogenesis during regeneration followed a
similar pattern in these two species regardless of the amount of anterior tissue lost, progressing from wound healing to formation
of a recognizable prostomium and peristomium (“head”) by 6 days post-ablation. Palp and setal growth, addition of segments,
and formation of nuchal organs and the ciliated food groove followed so that worms appeared to have re-grown “normal,” but
smaller, “heads” and palps by 9–12 days following ablation. Over the course of 16 days, worms that lost more segments regenerated
less tissue relative to their initial intact size and did so more slowly. There was no significant palp growth during the
first 3 days following ablation. Rate of segment addition was directly related to the degree of tissue loss in D. quadrilobata. P. elegans added segments at similar rates whether 50 or 70% of the original segments was removed. 相似文献
6.
We test the hypothesis that echolocation behavior can be used to find the border between bat habitats. Assuming that bats
react to background targets in “edge space” but not in “open space”, we determined the border between these two habitat types
for commuting individuals of the parti-colored bat Vespertilio murinus. We recorded sequences of bats’ echolocation signals while they flew parallel to the walls of large buildings and to the
ground and determined the signals’ average bandwidth, duration, and pulse interval. These parameters varied systematically
with the estimated horizontal and vertical distances between the bats and the background. A distinct effect of horizontal
distance to the background on echolocation behavior was found for horizontal distances of less than 6 m, thus indicating the
border between edge and open space. Only a few bats flew at vertical distances below 5 m. However, enough passages at vertical
distances of 5 m and above indicated that the vertical border is somewhere below a distance of 5 m. Within edge space, V. murinus reacted to the background by reducing signal duration, increasing bandwidth at closer distances, and often emitting one signal
per wing beat. In open space, signal parameters did not vary as a function of distance to the background. There, V. murinus emitted the longest signals with the narrowest bandwidth and often made one or two wing beats without emitting a pulse. With
our data we support with statistical methods the hypothesis that echolocation behavior reveals the border between the habitat
types “edge” and “open space”. 相似文献
7.
Greg W. Rouse Nerida G. Wilson Shana K. Goffredi Shannon B. Johnson Tracey Smart Chad Widmer Craig M. Young Robert C. Vrijenhoek 《Marine Biology》2009,156(3):395-405
We report observations on spawning and early development in bone-eating worms of the genus Osedax. Individual females of Osedax rubiplumus were observed at 1820 m depth freely spawning hundreds of oocytes, and females of an undescribed species, Osedax “orange collar”, were observed spawning in laboratory aquaria. Cytological and molecular analysis of the spawned oocytes
of two Osedax species revealed no evidence for the bacterial endosymbionts that the female worms require for their nutrition, suggesting
that the bacteria must be acquired later from the environment, as they are in other siboglinids. Individual O. “orange collar” females released an average of 335 (±130) eggs per day, but the number of oocytes spawned per day varied
greatly, suggesting that not all the females spawned daily. Fertilization rates of the spawned oocytes varied from 0 to 100%,
though most females showed nearly 100% fertilization rates. Oocytes spawned in the laboratory at 4–6°C were negatively buoyant.
If fertilized, these oocytes extruded polar bodies and then after at least four hours cleaved unequally. Subsequent cleavages
occurred in a spiral pattern at roughly 2-h intervals, resulting in free-swimming trochophore larvae after 24 h. These lecithotrophic
trochophores swam for 9–16 days before settling with several hooked chaetae, similar to those of dwarf Osedax males. The larval life span of the Osedax species studied in the laboratory appears to be shorter than in closely related Vestimentifera. Osedax rubiplumus, on the other hand, has much larger oocytes and so may have greater dispersal potential than these other Osedax species. The high fecundity and apparently continuous reproduction of Osedax boneworms permits the opportunistic exploitation of sunken vertebrate bones.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
The extent to which male birds in polygynous species with biparental care assist in nestling feeding often varies considerably
between nests of different mating status. Both how much polygynous males assist and how they divide their effort between nests
may have a profound effect on the evolution of mating systems. In this study we investigated how males in the facultatively
polygynous European starling Sturnus vulgaris invested in their different nests. The amount of male assistance affected the quality of the offspring. Polygynous males
invested as much as monogamous males, but divided their effort asymmetrically between nests, predominantly feeding nestlings
of first-mated (primary) females. Although females partly compensated for loss of male assistance, total feeding frequency
was lower at primary females’ nests than at monogamous females nests. Secondary females received even less assistance with
nestling rearing, and the extent to which males assisted decreased with the length of the interval between the hatching of
the primary and secondary clutches. These results are contrasted with those from a Belgian populations of starlings with a
much more protracted breeding season and thus greater opportunities for males to attract additional mates during the nestling
rearing period. The results show that both the “defence of male parental investment model” and the “asynchronous settlement
model” have explanatory power, but that their validity depends on the potential length of the breeding season.
Received: 21 July 1995/Accepted after revision: 13 July 1996 相似文献
9.
Interval between reproductive events is an important factor for iteroparous animals because it determines the number of clutches
throughout life. This study examined whether female size, clutch size, shell size and prenuptial molting affected the clutch
interval in the hermit crab Pagurus nigrivittatus. Precopulatory guarding pairs of P. nigrivittatus were sampled in the field and kept in the laboratory until the female extruded eggs. The clutch interval of each female was
assessed as one of two types of relatively “short” and “long” intervals by checking whether the guarded female had eggs and/or
egg cases from the preceding brood or not when the guarding pair was collected. The clutch interval was longer in females
with prenuptial molting than those without molting and these females usually grew larger at the prenuptial molt. This suggests
that female P. nigrivittatus with a long interval might allocate energy into growth at the expense of the number of clutches during the current reproductive
season. The allocation to growth is theoretically predicted to decrease with female size. Gastropod shell size is also known
to affect the reproductive activity in hermit crabs. However, female size did not significantly affect the clutch interval
in P. nigrivittatus, and the effect of gastropod shell size on clutch interval was not consistent with previous empirical studies. These results
may be caused by differences in the gastropod species of shell occupied by the females of P. nigrivittatus. 相似文献
10.
Bruce Lyon 《Behavioral ecology and sociobiology》2007,61(3):455-463
Hosts of avian brood parasites use a variety of defenses based on egg recognition to reduce the costs of parasitism; the most important of which is rejecting the parasitic eggs. Two basic recognition mechanisms are possible: “true recognition”, whereby hosts recognize their own eggs irrespective of their relative frequency in the clutch, and minority recognition (or “recognition by discordancy”), whereby hosts respond to the minority egg type. The mechanism of recognition has been experimentally studied in a handful of species parasitized by interspecific brood parasites, but the mechanism used in defenses against conspecific brood parasitism is unknown. I experimentally determined the mechanism of egg recognition in American coots (Fulica americana), a species with high levels of conspecific brood parasitism, egg recognition, and rejection. I swapped eggs between pairs of nests to alter frequencies of host and “parasite” eggs and then used two criteria for recognition: egg rejection and nonrandom incubation positions in the clutch. Eight of 12 nests (66%) given equal frequencies of host and parasite eggs showed evidence of true recognition. In contrast, only one of eight (12.5%) nests where host eggs were in the minority showed evidence of recognition by discordancy. The nonrandom incubation positions of parasitic eggs indicates that birds sometimes recognize parasitic eggs without rejecting them and provides a means of assessing recognition on a per nest basis in species with large clutches. Adaptive recognition without rejection may also be an important evolutionary stepping stone to the evolution of egg rejection in some taxa. 相似文献
11.
Life history of Gonatus onyx (Cephalopoda: Teuthoidea): deep-sea spawning and post-spawning egg care
A reproductive strategy consisting of deep- water spawning and egg-care was inferred for the midwater squid Gonatus onyx Young, 1972. Brooding females and associated eggs and hatchlings, captured between 1250 and 1750 m depth off southern California,
are described. Brooding females appear to be senescent and lack tentacles. Large eggs of this species (3 mm) at cold temperatures
(3 °C at capture depth) may require as long as 9 mo to develop. The high lipid content of the digestive gland in adult females
of this species may provide fuel to support such an extended “brooding” period.
Received: 22 February 1999 / Accepted: 25 May 2000 相似文献
12.
In the shrimp Crangon crangon, an important fishery resource and key species in the southern North Sea, we studied temporal variations in size, biomass
(dry weight, W) and chemical composition (C, N, protein and lipid) of eggs in an initial embryonic stage. Data from 2 years, 1996 and 2009,
consistently revealed that egg size and biomass varied seasonally, with maxima at the beginning of the reproductive season
(January), decreasing values throughout spring, minima in June–July, and a slight increase thereafter. This cyclic pattern
explains why “Winter eggs” are on average larger and heavier than “summer eggs”. Using a modelling approach, we estimated
the duration of oogenesis in relation to seasonally changing seawater temperatures. According to an additive model of multiple
explanatory variables, the C content per newly laid egg showed in both years a highly significant negative relationship with
day length (r2 = 0.38 and 0.40, respectively; P < 0.0001), a weak positive relationship with temperature (r2 = 0.08 and 0.09; P < 0.05), and a weak negative relationship with phytoplankton biomass (r2 = 0.11 and 0.12; P < 0.05) at the estimated time of beginning oogenesis. Phenotypic plasticity in initial egg size and biomass is interpreted
as an adaptive reproductive trait that has evolved in regions with strong seasonality in plankton production and periods of
larval food limitation. In contrast to biomass per egg, the percentage chemical composition remained similar throughout the
reproductive period. Both the absolute and percentage values also showed significant interannual variations, which caution
against generalizations based on short-term studies of reproductive traits of C. crangon and other species of shrimp. 相似文献
13.
Females across many taxa commonly use multiple or complex traits to choose mates. However, the functional significance of
multiple or complex signals remains controversial and largely unknown. Different elements of multiple or complex signals may
convey independent pieces of information about different aspects of a prospective mate (the “multiple messages” hypothesis).
Alternatively, multiple or complex signals could provide redundant information about the same aspect of a prospective mate
(the “redundant” or “back-up” signal hypothesis). We investigated these alternatives using spadefoot toads, Scaphiopus couchii. Spadefoot toads primarily use calls to attract their mates, but males also exhibit sexually dimorphic coloration. We investigated
whether male coloration is indicative of male size, condition, or infection status by a socially transmitted monogenean flatworm.
We found that male coloration and dorsal patterning predicts male size and condition but not infection status. Moreover, when
we presented females with a choice between a bright male model and a dark male model, we found that females preferred the
bright model. Because aspects of males’ calls are also associated with male size and condition, we conclude that coloration
is a potentially redundant indicator of male phenotype. We suggest that coloration could enhance mate choice in conjunction
with male calling behavior by providing females with a long distance cue that could enable them to identify prospective mates
in a noisy chorus environment where the discrimination of individual calls is often difficult. Generally, such redundant signals
may facilitate mate choice by enhancing the quality and accuracy of information females receive regarding prospective mates. 相似文献
14.
Symbion americanus was recently described as the second species in the phylum Cycliophora, living commensally on the American commercial lobster
Homarus americanus. A previous genetic analysis of American and European populations of cycliophorans suggested that haplotype divergence in
S. americanus was much greater than in its European counterpart S. pandora. This study examined the population structure and demographics of 169 individuals thought to belong to S. americanus collected from lobsters over 13 North American localities (Nova Scotia, Canada to Maryland, USA) between October 2003 and
January 2006. Cytochrome c oxidase subunit I sequence data clearly suggested the presence of three cryptic lineages in a species complex, often co-occurring
in the same lobster specimens. One of these lineages, named the “G” lineage, was represented by very few individuals and therefore
was excluded from subsequent statistical analyses. The other two sympatric lineages, named the “T” and “C” lineages, showed
different population structure and demography. Although limited geographic structure was found in the T lineage, the C lineage
showed higher nucleotide and haplotype diversity values, as well as more variation between localities. The data also indicated
that the T lineage underwent a recent population expansion, suggesting that the C and T lineages may have speciated in allopatry
but a subsequent population expansion may have been responsible for their current sympatric distribution. Studies on the anatomy
and ecology of the sympatric lineages of this species complex should provide further information on the identity of the holotype
of S. americanus, which currently cannot be ascribed to any of the three cryptic lineages. 相似文献
15.
Five hypotheses have been proposed to explain polygyny in the red-winged blackbird (Agelaius phoeniceus). We categorized the hypotheses into three groups based on female preference for unmated versus monogamously mated males:
(1) the “polygyny threshold” model, “sexy son” hypothesis and the “asynchronous settlement” model, which assume that females
prefer unmated males to mated males on breeding situations of homogeneous quality; (2) the “neutral mate choice” hypothesis,
which assumes that females have no preference; and (3) the “cooperative female choice” model, which assumes that females prefer
monogamously mated males to unmated males. We tested the direction of female preference in two field experiments. In both
experiments, newly settling females were given a choice of two adjacent territories, one defended by an unmated male and the
other by a monogamously mated male. Male mating status was randomized with respect to the variation in territory quality and
male quality. Early in the breeding season, significantly more females settled with the unmated males than with the mated
males. Although more females settled with the unmated males than with the mated males late in the breeding season, the difference
was no longer significant. Female settlement late in the season appeared to be related to the tenure of the resident females:
the new females avoided territories where the resident females were in early stages of their nesting, but settled on territories
where the resident females were in late stages. The pattern of female settlement shows that females prefer unmated males to
mated males. The preference is consistent with the polygyny threshold model, sexy son hypothesis and the asynchronous settlement
model, and inconsistent with the neutral mate choice hypothesis and the cooperative female choice model. For this reason,
the latter two hypotheses are unlikely to explain the occurrence of polygyny in our population of red-winged blackbirds.
Received: 1 December 1994 / Accepted after revision: 28 October 1995 相似文献
16.
Mathieu Pernice Delphine Pichon Isabelle Domart-Coulon Jocelyne Favet Renata Boucher-Rodoni 《Marine Biology》2007,150(5):749-757
The recent application of molecular tools to address associations between bacteria and marine invertebrates has provided access
to an immense diversity of unidentified microbes resistant to cultivation. However, the role of bacteria as partners in animal
physiology remains unclear and in most cases difficult to investigate in the absence of adequate condition of cell growth
and proliferation. In this work, we studied the reservoir of microbes associated with the excretory organs of Nautilus macromphalus as a model. Using the bacterial 16S RNA gene as a marker, we compared three complementary approaches for bacterial detection:
bacterial DNA extraction from N. macromphalus tissues (“molecular approach”), strain isolation to provide a bacterial culture collection (“microbiological approach”) and
finally, maintenance of N. macromphalus excretory organ cells with associated bacteria (“cellular approach”). Our results stress the potential of the “cellular approach”
as a promising new tool as it promotes the detection of as yet uncultured β-proteobacteria and spirochaetes associated with
N. macromphalus, and serves as a foundation for future studies describing potential roles that these bacteria may play in Nautilus. 相似文献
17.
Facultative traits that have evolved under sexual selection, such as the acoustic ornaments present in the advertisement signals
of male túngara frogs (Physalaemus pustulosus), offer a unique opportunity to examine selection for trait exaggeration with a focus on individual differences amongst signalers.
By contrast, many studies of mate choice use experimental designs that obscure the inter-individual variation amongst signalers
available for selection to act on—through the use of “typical” or average signals from the population. Here, we use dichotomous
female phonotaxis choice tests to determine how the value of male call embellishment varies across 20 individual males frogs
recorded from the wild—a sample which captures the acoustic diversity present in the population. We tested 20 females for
each male call pair (i.e., 400 females). The results show widespread preference amongst females for ornamented calls (“whine–chucks”)
over simple calls (“whines”), yet also demonstrate substantial variation in the relative benefits for individual male frogs—some
males enjoy appreciable benefits by using ornaments while others (30% of males in this study) do not. We also show that the
relative amplitude of the chuck to the whine correlates positively with the value of call elaborations across these 20 males.
Finally, by manipulating the relative amplitude of whines and chucks using both natural and synthetic calls, we demonstrate
directly that this single call parameter is key to determining the relative value of call elaborations across males. 相似文献
18.
The anchovy (Engraulis ringens) and common sardine (Strangomera bentincki) are two small pelagic fish which have a similar reproductive strategy off central southern Chile. The seasonal reproductive
dynamics of both the species was investigated by taking into account the gonadosomatic index (GSI) and visual maturity data
as a function of female size for the period 1993–1999, and also the seasonal pattern in condition factor per size classes.
Larger females of common sardine (repeat spawners) have a reproductive peak earlier in the season than younger females at
first maturity, while larger anchovy have a reproductive peak delayed as compared with first-time spawners. The condition
factor of females exhibited an inverse cycle with the seasonal pattern of GSI, and delayed by approximately 6 months. Although
larger females tend to present better and wider condition than smaller females, the condition of females seems to be delayed
in larger females probably mediated by the seasonal pattern in food availability. This “energy storage strategy” in spring
and summer time seems to be size-dependent and past energetic reserves could also affect the egg production and timing of
reproduction. We concluded that the reproductive season of anchovy and common sardine is different and mediated by the length
structure in the seasonal upwelling system off central southern Chile. 相似文献
19.
Jonathan N. Pruitt Nicholas DiRienzo Simona Kralj-Fišer J. Chadwick Johnson Andrew Sih 《Behavioral ecology and sociobiology》2011,65(10):1987-1995
Research on consistent individual differences in behavior, or “behavioral syndromes”, continues to grow rapidly, and yet,
the aspects of behavior under consideration have remained remarkably limited. Here, we consider individual variation in consistency
of choice (termed here “choosiness”), as expressed during habitat choice. We repeatedly tested the responses of female Western
Black Widows, Latrodectus hesperus, to two cues of habitat quality: prey chemical cues and variation in web site illuminance. We estimated females’ response
by the distance they positioned themselves from (1) the source of prey chemical cues and (2) the darkest edge of our test
arena. Individuals with low variance in their responses are deemed more “choosy”, whereas individuals with high variance are
deemed less “choosy”. Generally, most females initiated web construction near the source of the prey chemical cues and tended
to place themselves in low-light conditions. However, we detected strong, repeatable differences in females’ intensity of
response, and within-individual variance of response (i.e., choosiness) was correlated across situations: females with highly
consistent responses towards cricket chemical cues also exhibited highly consistent responses towards variation in light conditions.
When deprived of food for extended periods, females were indistinguishable in their responses towards prey chemical cues,
but tended to initiate web construction in brighter lighting conditions. Food-deprived females universally exhibited higher
variance and diminished consistency in their responses (i.e., they were less choosy). Additionally, higher choosiness was
associated with greater mass loss during choice trials, suggesting choosiness is energetically costly. Our results demonstrate
that consistency of response to environmental cues is yet another element of behavior that varies among individuals and variation
in choosiness could beget speed/quality trade-offs during animal decision making. 相似文献
20.
Peter H. W. Biedermann Kier D. Klepzig Michael Taborsky 《Behavioral ecology and sociobiology》2011,65(9):1753-1761
Body reserves may determine the reproductive output of animals, depending on their resource allocation strategy. In insects,
an accumulation of reserves for reproduction is often obtained before dispersal by pre-emergence (or maturation) feeding.
This has been assumed to be an important cause of delayed dispersal from the natal nest in scolytine beetles. In the cooperatively
breeding ambrosia beetles, this is of special interest because in this group delayed dispersal could serve two alternative
purposes: “selfish” maturation feeding or “altruistic” alloparental care. To distinguish between these two possibilities,
we have experimentally studied the effect of delayed dispersal on future reproductive output in the xyleborine ambrosia beetle
Xyleborus affinis. Females experimentally induced to disperse and delayed dispersing females did not differ in their body condition at dispersal
and in their founding success afterwards, which indicates that females disperse independently of condition, and staying adult
females are fully mature and would be able to breed. However, induced dispersers produced more offspring than delayed dispersers
within a test period of 40 days. This suggests that delayed dispersal comes at a cost to females, which may result primarily
from alloparental care and leads to a reduced reproductive output. Alternatively, females might have reproduced prior to dispersal.
This is unlikely, however, for the majority of dispersing females because of the small numbers of offspring present in the
gallery when females dispersed, suggesting that mainly the foundress had reproduced. In addition, “gallery of origin” was
a strong predictor of the reproductive success of females, which may reflect variation in the microbial complex transmitted
vertically from the natal nest to the daughter colony, or variation of genetic quality. These results have important implications
for the understanding of proximate mechanisms selecting for philopatry and alloparental care in highly social ambrosia beetles
and other cooperatively breeding arthropods. 相似文献