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121.
Lutz Fromhage Michael Jennions Hanna Kokko 《Evolution; international journal of organic evolution》2016,70(3):617-624
Searching for mates is a critical stage in the life cycle of most internally, and many externally, fertilizing species. Males usually invest more in this costly activity than females, but the reasons for this are poorly understood. Previous models have shown that female‐biased parental investment, including anisogamy, does not by itself select for male‐biased mate searching, so it requires additional explanations. Here, we correct and expand upon earlier models, and present two novel hypotheses that might explain the evolution of male‐biased mate searching. The “carry‐over hypothesis” states that females benefit less from searching if the associated costs affect other stages of the life cycle, rather than arising only while searching. It is relevant to the evolution of morphological traits that improve searching efficiency but are also expressed in other contexts. The “mating window hypothesis” states that females benefit less from searching if their life cycle includes intervals during which the exact timing of mating does not matter for the appropriate timing of reproduction (e.g., due to sperm storage or delayed embryo implantation). Such intervals are more likely to exist for females given the general pattern of greater female parental investment. Our models shed new light on classic arguments about sex role evolution. 相似文献
122.
To study sex-differential allocation of maternal behavior in Microcebus murinus, I recorded behavioral patterns on 21 litters from parturition to the weaning period. After a pregnancy of 61.5 ± 0.9 days, females may produce from one to four young per litter. Litters were weaned in 40 days by mothers. Behavioral observations at the beginning of the nocturnal activity period demonstrated that close contacts between mothers and infants were more frequent in multiparous mothers than in primiparous ones (p < .01). Time in close contact with offspring aged >15 days old compared to contacts with neonates is significantly lower only in single-sex litters and is more marked for all-female litters (p < .01). Mother's approaches toward mixed litters or all-male litters were always significantly greater than approaches toward all-female litters (p = .04). However, mother's approaches within mixed sex litters were not biased toward either sex (p = .7). Males in a litter may be interpreted as a stimulator of maternal behavior. Similarly, using retrieving tests of 15-min duration, a significant maternal preference for male neonates is evident. Latency to first retrieval is significantly shorter in multiparous females than in primiparous ones (p < .05) independent of size and sex ratio of the litter. For multiparous females only, male neonates were chosen first for retrieval more often than females (p < .05). Finally, the calls of young played a stimulator effect on maternal retrieving (p < .001). Accordingly multiparous mothers exhibit more interest in their young, which appears to be biased toward male neonates. 相似文献
123.
Kermyt G. Anderson Hillard Kaplan David Lam Jane Lancaster 《Evolution and human behavior》1999,20(6):79
In this article we present a biosocial model of human male parental care that allows relationship (mating) effort to influence male parental allocations. The model recognizes four classes of relationships between men and the children they parent: genetic offspring of current mates (combined relationship and parental effort), genetic offspring of previous mates (parental effort solely), step offspring of current mates (relationship effort solely), and stepchildren of previous mates (essentially no expected investment). We test the model using data on parental investment collected from 340 Xhosa high school students in Cape Town, South Africa. Six measures of paternal investment are examined: the amount of money men spent on students for school, clothing, and miscellaneous expenditures, respectively, and how often men spent time with children, helped them with their homework, or spoke English with them. The tests provide support for the roles of both parental and relationship effort in influencing parental care: men invest significantly more in their genetic offspring and in the children of their current mates. We also examine several proximate influences on parental care, specifically the age and sex of the child, and the percentage of the child's life the father figure coresided with him or her. 相似文献
124.
We present a biosocial model of human male parental care that allows male parental allocations to be influenced not only by changes in the fitness (welfare) of the recipient offspring, but also by their effects on the man's relationship with the child's mother. The model recognizes four classes of relationships between males and the children they parent: genetic offspring of current mates (combined relationship and parental effort), genetic offspring of previous mates (parental effort solely), step offspring of current mates (relationship effort solely), and stepchildren of previous mates (essentially no expected investment). We test the model using data on parental investments collected from adult males living in Albuquerque, New Mexico, U.S.A. Four measures of paternal investment are examined: the probability that a child attends college (2,191 offspring), the probability that a child who attends college receives money for it (N = 1,212), current financial expenditures on children (N = 635), and the amount of time per week that men spend with children ages 5 to 12 years (N = 2,589). The tests are consistent with a role for relationship effort in parental care: men invest more in the children of their current mates, even when coresidence with offspring is not a confounder. 相似文献
125.
Active female courtship behavior and male nutritional contribution to female fecundity in Bruchidius dorsalis (Fahraeus) (Coleoptera: Bruchidae) 总被引:3,自引:0,他引:3
Koh-ichi Takakura 《Population Ecology》1999,41(3):269-273
Mating behavior and the male's contribution to female fecundity were studied in the bean weevil Bruchidius dorsalis (Fahraeus) (Coleoptera: Bruchidae) in comparison with two other species, Callosobruchus chinensis (which infests stored beans) and Kytorhinus sharpianus (which feeds on wild legumes). Only females of B. dorsalis showed multiple mating and characteristic precopulatory behavior that appeared to solicit the male's nutritious secretion.
In contrast, all females of the other two species did not copulate multiply and did not show such precopulatory behavior.
In B. dorsalis, the decrement of male body weight just after copulation indicated that seminal fluid weighing as much as approximately 7%
of the male's body weight was transferred to the female. Fecundity was more than eight times higher in females that had copulated
ten times than in females that had copulated only once, indicating that males paid most of the nutritional cost of egg production.
These facts suggest that the sex role is reversed in B. dorsalis.
Received: May 22, 1998 / Accepted: July 19, 1999 相似文献
126.
Influence of resource level on maternal investment in a leaf-cutter bee (Hymenoptera: Megachilidae) 总被引:2,自引:0,他引:2
Fisher's (1930) prediction
of equal investment for each sexin a panmictic population is influenced by a
number of ecologicalfactors, among which resource availability plays a major
role,particularly when the population exists under changing resource
availability.Rosenheim et al. proposed a multifaceted parental investment
modelbased on the underlying assumption that individual females determine
theirsex investment according to resource availability and oocyte
availabilityto maximize reproductive success. The model predicts that greater
availabilityof resources used for provisions will lead to (1) an increasein
the proportion of females produced (when the female is thelarger sex) and (2)
an increase in the amount of provisionsper offspring and thus an increase in
offspring size. I testedthese predictions by a controlled experiment using a
leaf-cutterbee, Megachile apicalis. I presented two levels of food
resourcesto the nesting females, which were allowed to forage and nestin
cages. The experimental results supported these parentalinvestment model's
predictions. 相似文献
127.
Susan Huang Natalie Driessen Michael Knoll P. Talbot 《Molecular reproduction and development》1997,47(3):312-322
In mammals, the oocyte and its surrounding cumulus cells constitute an oocyte cumulus complex (OCC). During ovulation, OCCs are extruded into the peritoneal or bursal cavity, depending on the species, and are then rapidly picked up by the fimbria on the outer surface of the oviductal infundibulum and transported to the ampulla, where fertilization occurs. We developed a method to measure OCC pickup rates quantitatively in vitro, and we used this method to evaluate the effects of viscosity and temperature on pickup rates. Hamster infundibula are placed in a holding pipette in a chamber modified to study OCC pickup. Ciliary beat frequencies (CBF) can be measured in the same preparation. Pickup rates vary depending on the pathway on which the OCC travels over the surface of the infundibulum; however, rates for a given pathway are very consistent. The average pickup rate at room temperature calculated from three different pathways/infundibulum was 55.2 ± 10.6 μm/sec. Both rates between infundibula from the same female and rates among infundibula from different females were in most cases similar. Preparations preincubated in vitro for 2.75 hr produced rates similar to nonpreincubated samples, while longer preincubation resulted in decreased rates. Inclusion of Ficoll in culture medium to increase viscosity caused a concentration-dependent decrease in both OCC pickup rate and in CBF. However, a significant decrease in OCC pickup rate was only observed at viscosities higher than those found in bursal fluid. When trials were run at physiological temperature (36.4°C) rather than ambient temperature, rates increased to 136.7 ± 29.9 (SD) μm/sec. Linear regression analysis demonstrated a strong positive correlation (r = 0.94) between OCC pickup rate and temperature. The OCC pickup rate assay can be used experimentally, and should be valuable in evaluating factors that affect rate and in studies dealing with the mechanism of OCC pickup. Mol. Reprod. Dev. 47:312–322, 1997. © 1997 Wiley-Liss, Inc. 相似文献
128.
The evolution of the life cycle of brown seaweeds 总被引:2,自引:0,他引:2
The brown seaweeds (Phaeophyta) are well-suited for testing theories of the evolution of the sexual alternation of haploid and diploid generations because of the great diversity of life cycles within the phylum. Three theories are investigated in this paper. (1) Diploid growth evolves because it has the effect of complementing deleterious recessive mutations. This is rejected because (a) ancestral haplonty is not a parsimonious inference from current phylogenies; (b) the exaggeration of diploid growth does not evolve in a comb-like fashion; (c) forms with predominantly haploid growth have evolved from smaller isomorphic ancestors; and (d) there is no correlation between haploid growth and monoecy. (2) Diploid growth evolves when gamete dimorphism leads to intense sexual selection, favouring the production of genetically diverse gametes through meiosis. This is rejected because diere is no correlation between the dominance of the diploid generation and the degree of gamete dimorphism. It is possible to show that gamete dimorphism itself has evolved in the Phaeophyta through the increase in size of the macrogamete in forms that have evolved larger sporophytes. (3) Microthalli become specialized as gametophytes because fusion is promoted by releasing gametes into the boundary layer; macrothalli become specialized as sporophytes because dispersal is promoted by releasing zoospores into the water column. This is consistent with the sexual and reproductive biology of Phaeophyta. The classic sexual cycle can then be interpreted as evolving from an asexual alternation of microthallus and macrothallus, governed largely by environmental factors, through selection for the appropriate association of ploidy with vegetative size. The exceptions to this general rule are forms in which gametes are released from macrothalli, where a different suite of sexual characters has evolved. 相似文献
129.
Asymmetric paternal effect on offspring size linked to parent‐of‐origin expression of an insulin‐like growth factor 下载免费PDF全文
Yolitzi Saldivar Lemus Jean‐Philippe Vielle‐Calzada Michael G. Ritchie Constantino Macías Garcia 《Ecology and evolution》2017,7(12):4465-4474
Sexual reproduction brings together reproductive partners whose long‐term interests often differ, raising the possibility of conflict over their reproductive investment. Males that enhance maternal investment in their offspring gain fitness benefits, even if this compromises future reproductive investment by iteroparous females. When the conflict occurs at a genomic level, it may be uncovered by crossing divergent populations, as a mismatch in the coevolved patterns of paternal manipulation and maternal resistance may generate asymmetric embryonic growth. We report such an asymmetry in reciprocal crosses between populations of the fish Girardinichthys multiradiatus. We also show that a fragment of a gene which can influence embryonic growth (Insulin‐Like Growth Factor 2; igf2) exhibits a parent‐of‐origin methylation pattern, where the maternally inherited igf2 allele has much more 5′ cytosine methylation than the paternally inherited allele. Our findings suggest that male manipulation of maternal investment may have evolved in fish, while the parent‐of‐origin methylation pattern appears to be a potential candidate mechanism modulating this antagonistic coevolution process. However, disruption of other coadaptive processes cannot be ruled out, as these can lead to similar effects as conflict. 相似文献
130.