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This study examines the optimal seasonal timing of the life cycle for univoltine and bivoltine insects, assuming that resource
availability has a peak in the middle of a year and is symmetric around it. Results show that if the growth rate increases
in proporrion to the bodyweight, bivoltine life cannot be optimal. If the growth rate is a power function of the bodyweight
with a power smaller than unity, a symmetric bivoltine solution can be the optimal provided that the resource availability
has a plateau in the middle of the season. If the resource availability has a sharp peak, the optimal pattern is an asymmetric
bivoltine solution in which the larval periods of two generations differ in length. The bivoltine life cycle is more likely
to be superior to the univoltine one if: growth is fast, suitable growing season is long, biomass loss during nonlarval stages
is small, and egg size is small. 相似文献
2.
Joachim L. DAGG 《动物学报》2006,52(5):819-826
某些物种的蚜虫中,雌性个体成熟较晚,可以认为是雄性个体的“侄女”。当冬季即将来临,剩余时间就不能满足发育需求时,发育延迟了,发育延迟应当也终止了雌性功能上的投资。然而,最近的证明表明,雌性功能的投资并不停止。这种未预料到的发现可能归因于一种进化限制因素,归因于雄性个体在不同年龄阶段对配偶的竞争,或归因于不能预测导致随机非遗传多型性的最后期限。本文讨论了这三种可能性,最后一种可能性由于暂时性地解释了雌性功能中的连续投资而是一种可取的解释。尽管延缓发育和开始繁殖的最后期限常见于那些生活在严寒地区的、雌性发育迟缓的蚜虫,本文的观点也适合于一个性别成熟较晚的、具有繁殖最后期限的任何一个蚜虫物种。 相似文献
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Bumblebees are generally believed to be annual insects. However, here we will show that under laboratory conditions the bumblebee Bombus terrestris (L.) can produce a second generation without a period of cold storage (diapause) or CO2 narcosis (a method to break diapause). It is also shown that this so-called non-diapause trait can be selected for. The percentage of non-diapausing queens increased from 8% (minimum) to 97% (maximum) in two generations of selection. However, it was not possible to maintain isofemale non-diapause lines. Colonies of the fourth and fifth generation remained small (expressed in worker number) and produced a small number of queens. Also the percentage of queens that started laying eggs (defined as the percentage non-diapause) decreased in the fourth and fifth generations. To study whether this decline of the non-diapause lines was caused by inbreeding, a control experiment was conducted. In this control experiment queens were mated with their brothers (full-sib mating) for several generations and the number of queens that start egg laying was measured. This revealed that inbreeding can have a negative effect on the egg-laying capacities of queens thus causing the decline of inbred (non-diapause) lines. 相似文献
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Ottavio Soppelsa Pasquale Raia Valeria Maselli Domenico Fulgione 《Molluscan research.》2013,33(2):80-86
We analysed ontogenetic shape change in the planorbid limpet Ancylus fluviatilis (Müller, 1774) in two rivers in Southern Italy. We developed a new method to discriminate among different cohorts in Ancylus, based on principal component analysis. The method is useful when shape change during growth is allometric, as in our study model. We discovered that bivoltinism occurs in Ancylus in Southern Italy, contrary to previous accounts, which invariably describe A. fluviatilis as a semelparous and univoltine species, although acknowledging difficulty in discriminating among cohorts. The methods presented here may potentially help research in reproductive traits in many other mollusc populations where shape change during ontogeny is demonstrated to be allometric. 相似文献
5.
Yosiaki Itô 《Ecological Research》1996,11(1):79-87
A strong typhoon, Typhoon 13, which swept through Okinawa on 2 and 3 September 1993, knocked down 57 to 61 of 97Ropalidia fasciata nests. Thirty-five colonies soon reconstructed their nests, and these nests produced 54±46 adults per nest during the remaining
two and a half months before winter. The number of females involved in nest reconstruction was 21.3±15.7 per nest. The frequency
of foraging activity was significantly higher in nests being reconstructed than in normal nests. As only one out of 205 foundresses
marked in spring was found in early September, most cases of nest reconstruction were considered to be made exclusively by
females that emerged during the spring and summer of 1993 (progeny females). All of the reconstructed nests but one produced
adult females. Many females (31%) collected from the two reconstructed nests were inseminated. As all the reconstructed nests
became vacant by early January, indicating completion of the colony cycle, and a large number of nests were established in
the spring of 1994, females emerging from reconstructed nests in 1993 probably become foundresses in 1994.Ropalidia fasciata is considered to be, at least partially, bivoltine in Okinawa. The significance of these facts for the evolution of multi-queen
social systems in the Polistinae is discussed. 相似文献
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We examined the female-biased sex ratio of a trap-nesting wasp Trypoxylon malaisei considering the following factors: (1) local mate competition (LMC), (2) resource quality, (3) partial bivoltinism, and (4)
presence of constrained females. The sex ratio (expressed as male ratio) at emergence was strongly female biased, i.e., 0.30
and 0.19, in terms of the number and investment, respectively. To evaluate the primary sex ratio, we analyzed the data from
nests where all the offspring successfully emerged, excluding nests composed of single-sex offspring. The primary sex ratio
was also female biased, at 0.33 and 0.21, in terms of the number and investment, respectively. LMC was highly responsible
for the female-biased sex ratio because both the nonrandom oviposition sequence [females at inner cells and male(s) at outer
cells] and earlier emergence of males allowed sib-matings to occur. In contrast, the other three factors little affected the
female-biased sex ratio: the sex ratio was fairly constant when resource quality (nest size) varied, partial bivoltinism was
extremely rare or absent, and constrained females were absent or did not reproduce at all.
Received: June 19, 1998 / Accepted: January 18, 1999 相似文献
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