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Ming-feng Chuang - One of the best experts on this subject based on the ideXlab platform.
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Predation risk and breeding site value determine Male behavior and indirectly affect survivorship of their offspring
Behavioral Ecology and Sociobiology, 2017Co-Authors: Ming-feng ChuangAbstract:Predation is one of the main drivers of behavioral adaptation in prey. In species with parental care, predation can affect survival of both adults and the offspring under their care. This effect can be further modulated by or combined with other factors that contribute to mating and reproductive success of adults, such as the quality of their breeding site. Using the nest guarding behavior of a treefrog with paternal Egg attendance, Kurixalus eiffingeri, we quantify the effects of predation on the behavior of adult frogs and the survival of their offspring. We observed predator avoidance behavior of Male frogs guarding empty breeding sites or breeding sites with Eggs in response to the introduction of a predatory snake, Dinodon rufozonatum. We hypothesized that Male nest guarding behavior would be negatively correlated with predation risk and positively correlated with their clutch sizes. Furthermore, we predicted that predator avoidance in Male frog would negatively impact the survivorship of their offspring. We found that breeding site fidelity in Male frogs was determined by perceived predation risk and breeding site value, with more Males abandoning sites when exposed to high mortality risks (presence of a snake) and when the reproductive benefits (number of offspring) were low. In addition, we found that the willingness of Males to return to their breeding sites was positively correlated with their clutch sizes. Abandoning breeding sites, however, can be costly to Males, because abandoned Eggs had a lower hatching rate. Our findings provide empirical evidence of how the costs and benefits of predation risk and breeding site value can determine the behavior of an amphibian with parental care. When faced with predation risks, the willingness of individuals to maintain their ownership over nest sites can have significant effects on their reproductive success. For species with parental care, nest defense can also be critical for offspring survival. Using an East Asian treefrog with Male Egg attendance, we hypothesized that Males would maximize their reproductive output by increasing investment for nest sites with low predation risks and with more offspring. We found that Males are more likely to invest in nest attendance when risks are low and benefits of offspring survival are high. Moreover, we found that the willingness of Males to continue parental investment resulted in an increase in survivorship of their offspring. Our results show that perceived risks and benefits to the adults are important factors in determining offspring survival in an amphibian species with parental care.
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Predation risk and breeding site value determine Male behavior and indirectly affect survivorship of their offspring
Behavioral Ecology and Sociobiology, 2017Co-Authors: Ming-feng ChuangAbstract:Predation is one of the main drivers of behavioral adaptation in prey. In species with parental care, predation can affect survival of both adults and the offspring under their care. This effect can be further modulated by or combined with other factors that contribute to mating and reproductive success of adults, such as the quality of their breeding site. Using the nest guarding behavior of a treefrog with paternal Egg attendance, Kurixalus eiffingeri, we quantify the effects of predation on the behavior of adult frogs and the survival of their offspring. We observed predator avoidance behavior of Male frogs guarding empty breeding sites or breeding sites with Eggs in response to the introduction of a predatory snake, Dinodon rufozonatum. We hypothesized that Male nest guarding behavior would be negatively correlated with predation risk and positively correlated with their clutch sizes. Furthermore, we predicted that predator avoidance in Male frog would negatively impact the survivorship of their offspring. We found that breeding site fidelity in Male frogs was determined by perceived predation risk and breeding site value, with more Males abandoning sites when exposed to high mortality risks (presence of a snake) and when the reproductive benefits (number of offspring) were low. In addition, we found that the willingness of Males to return to their breeding sites was positively correlated with their clutch sizes. Abandoning breeding sites, however, can be costly to Males, because abandoned Eggs had a lower hatching rate. Our findings provide empirical evidence of how the costs and benefits of predation risk and breeding site value can determine the behavior of an amphibian with parental care. When faced with predation risks, the willingness of individuals to maintain their ownership over nest sites can have significant effects on their reproductive success. For species with parental care, nest defense can also be critical for offspring survival. Using an East Asian treefrog with Male Egg attendance, we hypothesized that Males would maximize their reproductive output by increasing investment for nest sites with low predation risks and with more offspring. We found that Males are more likely to invest in nest attendance when risks are low and benefits of offspring survival are high. Moreover, we found that the willingness of Males to continue parental investment resulted in an increase in survivorship of their offspring. Our results show that perceived risks and benefits to the adults are important factors in determining offspring survival in an amphibian species with parental care.
Jaco M. Greeff - One of the best experts on this subject based on the ideXlab platform.
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Offspring allocation in externally ovipositing fig wasps with varying clutch size and sex ratio
Behavioral Ecology, 1997Co-Authors: Jaco M. GreeffAbstract:The simultaneous optimization of clutch size and sex ratio is a tricky problem. Unless parameters such as host size or fecundity exist to pin down the optimal clutch size, this problem remains elusive to analytical analysis. This is because the fitness landscape with respect to dutch size and sex ratio does not have one single evolutionarify stable peak toward which the population can evolve. To solve this problem, I used a computer emulation to optimize both dutch size and sex ratio using externally ovipositing fig wasps as a model taxon. The simulation approach allows the use of integer numbers of Eggs rather than assuming that feMales can produce any sex ratio between 0 and 1. When feMales have no information about the patches on which they oviposit, they produce either large dutches with a strong feMale bias or clutches of a single Male Egg. When feMales have complete knowledge of their oviposition site, a set of conditional substrategies is evohitionarih/ stable. Again, these substrategies are either large dutches with a feMale bias or dutches consisting of a single Male Egg. This dichotomous oviposition pattern results in unrelated Males sharing a fig, a condition conducive to the evolution of fatal fighting. Selection on feMale oviposition strategies may therefore be an important driving force behind high levels of fighting observed between Male fig wasps.
Earl R. Oatman - One of the best experts on this subject based on the ideXlab platform.
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Precise sex allocation, local mate competition, and sex ratio shifts in the parasitoid wasp Trichogramma pretiosum
Behavioral Ecology and Sociobiology, 2000Co-Authors: Robert F. Luck, J.a.m. Janssen, John D. Pinto, Earl R. OatmanAbstract:We determined the sex, order, and clutch size of Eggs laid by the parasitoid wasp, Trichogramma pretiosum Riley, in the Eggs of one of its natural hosts, Trichoplusia ni (Hubner). The parasitoid allocated sex non-randomly to hosts in the laboratory with a variance significantly less than that of a binomial (random) distribution, our null model. More clutches of two or more Eggs contained a single Male Egg as the second or third Egg laid than would be expected by chance and none contained two or more Male Eggs. T. pretiosum also increased the sex ratio (% Male) of its offspring with increasing foundress numbers by increasing the frequency of Male offspring as the second Egg in a two-Egg clutch allocated to unparasitized hosts and as the single Egg allocated to previously parasitized hosts. These results indicate that T. pretiosum allocates the sex of its offspring precisely. Precise sex allocation is favored under local mate competition because it reduces variation in the number of sons per patch thus maximizing the number of inseminated daughters emigrating from the patch. Similar combinations of feMale and Male offspring emerged from T. ni Eggs parasitized by T. pretiosum in the field, again with a sex ratio variance less than that expected for a binomial distribution. These results strongly suggest that this parasitoid species manifests local mate competition.
Ana Rivero - One of the best experts on this subject based on the ideXlab platform.
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Male Egg carrying in Phyllomorpha laciniata is favoured by natural not sexual selection
Animal Behaviour, 2008Co-Authors: Montserrat Gomendio, Francisco Garcia-gonzalez, P. Reguera, Ana RiveroAbstract:Two hypotheses could explain the evolution of paternal care: caring Males are more attractive to feMales and mate more often (sexual selection); Males care when the benefits in terms of offspring survival exceed the costs (natural selection). To test these hypotheses we used Phyllomorpha laciniata: feMales can choose whether to lay Eggs on plants or on conspecifics, and the extent to which Males carry Eggs varies between populations. Our results do not support the sexual selection hypothesis: feMales did not choose to mate with Egg-carrying Males in either natural populations or experimental contexts. We compared two populations that differ in the extent of Male Egg carrying and we show that in the population where Male Egg carrying was more prevalent, parasitism pressure was higher. Field experiments revealed that, in the population with high parasitism rate, Egg mortality as a result of parasitoid attack was up to 10 times higher on plants than on conspecifics. Egg carrying is thus an effective strategy that protects Eggs against parasitoids. We conclude that the main benefit derived by Males from Egg carrying is an increase in offspring survival, and that Males are sensitive to interpopulation differences in Egg mortality risks. Male care in this system has evolved despite intermediate levels of paternity certainty because the impact on offspring survival is high, and the costs in terms of loss of mating opportunities low. Thus, our findings support the natural selection hypothesis, although additional work on more populations is needed to verify this.
Marcel Honza - One of the best experts on this subject based on the ideXlab platform.
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Are House Wren Troglodytes aedon Eggs unusually strong? Test of the predicted effect of intraspecific Egg destruction: Strength of House Wren Eggs
Ibis, 2002Co-Authors: Jaroslav Picman, Marcel HonzaAbstract:As a result of opposing selective forces, the external strength of avian Eggs should be near some size-specific optimum. However, in certain situations there should be selection on feMales to lay unusually strong Eggs. According to one hypothesis, intraspecific Egg destruction should favour increased Egg strength as a means of defence against conspecific intruders. This hypothesis predicts that House Wrens Troglodytes aedon, a species well known for its tendency to destroy conspecific clutches, should be under selection for unusually strong Eggs. However, the intensity of selection for strong Eggs should also be modified by efficacy of nest defence against conspecific intruders in a given species (i.e. efficient nest defence by the breeding pair should weaken selection for unusually strong Eggs). The goals of our study were: (1) to establish whether House Wren Eggs are stronger than expected for their size; (2) to determine which structural mechanisms are responsible for their unusual strength; and (3) to test a hypothesis that, between wren species, the efficacy of nest defence and the intensity of Egg-destroying behaviour affect the intensity of selection for unusually strong Eggs. Our results demonstrated that: (1) House Wren Eggs are 1.9 times stronger than expected for their size; (2) their unusual strength is achieved mostly by their unusually thick shells; and (3) Eggs of the House Wren (extensive paternal nest defence; Male Egg-destroying behaviour suppressed during incubation) are significantly weaker structurally than Eggs of the Marsh Wren Cistothorus palustris (reduced paternal nest defence; Male Egg-destroying behaviour present throughout incubation). These results are consistent with the hypothesis that the intraspecific Egg-destroying behaviour and the efficacy of nest defence by the breeding adults have played a role in the evolution of strength of House Wren Eggs.