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paco.garcia[at]ebd.csic.es

Parental care

Publications filtered by: Parental care

Gomendio, M., Garcia-Gonzalez, F., Reguera, P. & Rivero A. 2008 Male egg-carrying in Phyllomorpha laciniata is favoured by natural not sexual selection Animal Behaviour, 75:763-770
Abstract

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.

The adaptive significance of male egg carrying in the golden egg bug: defining research avenues. A reply to Härdling et al
Garcia-Gonzalez, F., Roldan, E. R. S., Ponz, F. & Gomendio, M. 2007 The adaptive significance of male egg carrying in the golden egg bug: defining research avenues. A reply to Härdling et al Ecological Entomology, 32: 578-581
Paternity analysis in the golden egg bug using AFLPs: do the males preferentially accept their true genetic offspring?
Garcia-Gonzalez, F., Núñez, Y., Ponz, F., Roldán, E. R. S., & Gomendio, M. 2005 Paternity analysis in the golden egg bug using AFLPs: do the males preferentially accept their true genetic offspring? Ecological Entomology, 30: 444-455
Abstract

1. The evolution of parental care and intraspecific parasitism involve conflicts of interest between mothers and other potential care givers who contribute to enhance offspring survival. In the golden egg bug, Phyllomorpha laciniata Villers (Heteroptera: Coreidae), females lay eggs on conspecifics and on plants. The adaptive significance of egg carrying in this species has been the subject of some controversy, which can only be resolved by determining the genetic relationship between the eggs and the adult who carries them. This study examined whether male acceptance of true genetic offspring occurs with a higher frequency than that expected from random oviposition on conspecifics. 2. Paternity analysis, using Amplified Fragment Length Polymorphism (AFLP) markers, was conducted on eggs carried by males housed with field-mated females. 3. Out of the total number of eggs sired by males in the experimental groups, the proportion of eggs carried by males that were their true genetic offspring was 30.8%. 4. Monte Carlo methods show that the probability of a male accepting an egg that is his true genetic offspring is higher than expected if females dumped eggs on males at random. 5. These results suggest that paternal care plays an important role in the maintenance of male egg carrying in this species. In addition, the methodology developed may become useful in determining true genetic parents in other species in which neither the father nor the mother can be determined by observational methods.

¿Quién se ocupa de las crías?
Gomendio, M. & Garcia-Gonzalez, F. 2005 ¿Quién se ocupa de las crías? Quercus, 232: 46-51
Abstract
El cuidado de las crías no siempre recae sobre el mismo sexo. En los mamíferos, las hembras actúan como madres sacrificadas. En otros casos es el padre el que asume esta responsabilidad, como ocurre en algunas especies de peces. Entre las aves suele ser una tarea compartida por machos y hembras. Puesto que todas las combinaciones son posibles, cabe preguntarse ¿qué factores determinan que uno u otro sexo se ocupe de las crías?
Adjustment of copula duration and ejaculate size according to the risk of sperm competition in the golden egg bug (Phyllomorpha laciniata)
Garcia-Gonzalez, F. and Gomendio, M. 2004 Adjustment of copula duration and ejaculate size according to the risk of sperm competition in the golden egg bug (Phyllomorpha laciniata) Behavioral Ecology, 15:23-30
Abstract
Several hypotheses have been proposed to explain the adaptive significance of prolonged copulations in insects, which include mate guarding and sperm loading functions. We have explored the adaptive significance of the prolonged copulations in the golden egg bug (copulations up to 50 h) and the effect of an increased risk of sperm competition on ejaculate investment. Our data support predictions derived from sperm competition theory, which posits that males are expected to increase ejaculate expenditure in response to an increased risk of sperm competition. Results show a combined response by males that has not been previously described: males in the presence of rivals increase copulation duration and the rate of sperm transfer. No relationship was found between male or female size and copulation duration or ejaculate size. Golden egg bug males transfer sperm slowly and gradually throughout copulation; thus an increase in the amount of sperm transferred and the corresponding increase in the male’s numerical representation in the female’s storage organs could be particularly important in a system in which so few sperm are transferred and in which so few sperm are stored by females. In addition, copulation duration may not only serve to increase the total amount of sperm transferred, but it may also increase the chances that the female will lay an egg soon after copulation has ended. This could explain why males tend to accept eggs after copulation, since they could be maximizing the chances that such eggs are fathered by them, and in this way they would substantially increase the survival rates of their offspring because eggs laid on plants suffer high mortality rates.
Sperm competition mechanisms, confidence of paternity, and the evolution of paternal care in the golden egg bug (Phyllomorpha laciniata)
Garcia-Gonzalez, F., Núñez, Y., Ponz, F., Roldán, E. R. S., and Gomendio, M. 2003 Sperm competition mechanisms, confidence of paternity, and the evolution of paternal care in the golden egg bug (Phyllomorpha laciniata) Evolution, 57:1078-1088
Abstract

Theoretical models predict how paternal effort should vary depending on confidence of paternity and on the trade-offs between present and future reproduction. In this study we examine patterns of sperm precedence in Phyllomorpha laciniata and how confidence of paternity influences the willingness of males to carry eggs. Female golden egg bugs show a flexible pattern of oviposition behavior, which results in some eggs being carried by adults (mainly males) and some being laid on plants, where mortality rates are very high. Adults are more vulnerable to predators when carrying eggs; thus, it has been suggested that males should only accept eggs if there are chances that at least some of the eggs will be their true genetic offspring. We determined the confidence of paternity for naturally occurring individuals and its variation with the time. Paternity of eggs fertilized by the last males to mate with females previously mated in the field has been determined using amplified fragment length polymorphisms (AFLPs). The exclusion probability was 98%, showing that AFLP markers are suitable for paternity assignment. Sperm mixing seems the most likely mechanism of sperm competition, because the last male to copulate with field females sires an average of 43% of the eggs laid during the next five days. More importantly, the proportion of eggs sired does not change significantly during that period. We argue that intermediate levels of paternity can select for paternal care in this system because: (1) benefits of care in terms of offspring survival are very high; (2) males have nothing to gain from decreasing their parental effort in a given reproductive event because sperm mixing makes it difficult for males to reach high paternity levels and males are left with no cues to assess paternity; (3) males cannot chose to care for their offspring exclusively because they can neither discriminate their own eggs, nor can they predict when their own eggs will be produced; and (4) males suffer no loss of further matings with other females when they carry eggs. Thus, our findings do not support the traditional view that paternal investment is expected to arise only in species where confidence of paternity is high. The results suggest that females maximize the chances that several males will accept eggs at different times by promoting a mechanism of sperm mixing that ensures that all males that have copulated with a female have some chance of fathering offspring, that this probability remains constant with time, and that males have no cues as to when their own offspring will be produced.

A field test of the intraspecific brood parasitism hypothesis in the golden egg bug (Phyllormorpha laciniata)
Garcia-Gonzalez, F. and Gomendio, M. 2003 A field test of the intraspecific brood parasitism hypothesis in the golden egg bug (Phyllormorpha laciniata) Behavioral Ecology and Sociobiology, 53:332-339
Abstract

In natural populations of golden egg bugs (Phyllomorpha laciniata), females lay eggs on plants where they develop unattended, or on conspecifics, where they remain firmly glued until the nymphs hatch and start an independent life. Mortality rates among eggs laid on plants are higher than among eggs carried by adults. Because females cannot lay eggs on themselves, in order to improve offspring survival, they have to lay eggs on other individuals. Two hypotheses have been proposed to explain egg carrying: (1) the mating pair intraspecific brood parasitism hypothesis suggests that females dump eggs on copulating pairs, and (2) the paternal care hypothesis suggests that the system is driven mainly by males accepting eggs to improve the survival rates of their own offspring. Our data from the field show that 77% of the eggs are carried by males, because more males than females carry eggs, and because males carry a greater number of eggs. In addition, we show that mating males carry more recently laid eggs than single males. These results support the view that egg carrying is performed predominantly by males and that eggs are laid on males by their current mating partner, probably between repeated copulations. Males are likely to accept eggs, despite intermediate levels of paternity, because they cannot discriminate in favour of their own eggs, because rejected eggs will face 97% mortality rates on plants, and because they do not suffer mating costs when they carry eggs. However, females carry 23% of the eggs, but no differences in egg carrying have been found between mating and single females, suggesting that this is not the result of egg dumping while females are copulating. Egg carrying by females could reflect low levels of intraspecific parasitism, which is likely to reflect the low rate of successful attempts by egg-laying females who try to oviposit on other conspecifics rather indiscriminately, in an effort to improve the survival of their offspring.

Oviposition site selection and oviposition stimulation by conspecifics in the golden egg bug (Phyllormorpha laciniata): implications on female fitness
Garcia-Gonzalez, F. and Gomendio, M. 2003 Oviposition site selection and oviposition stimulation by conspecifics in the golden egg bug (Phyllormorpha laciniata): implications on female fitness Behavioral Ecology and Sociobiology, 53: 385-392
Abstract
Phyllomorpha laciniata Vill. (Heteroptera, Coreidae) females lay eggs on the host plant and on the backs of conspecifics. Since egg survival is greater when eggs develop on the backs of conspecifics than when laid on plants, we predict that females should prefer to lay eggs on conspecifics. In addition, because conspecifics are a high-quality site that represents a limiting resource, females should experience oviposition stimulation upon an encounter with a conspecific. Our results reveal that, when both the host plant and conspecifics are available simultaneously, females lay eggs preferentially on conspecifics. The results also support the second prediction, since females housed with conspecifics lay more than twice the number of eggs than isolated females. Isolated females do not seem to retain eggs, suggesting that oviposition stimulation is the result of an acceleration of egg-maturation rates. Other studies have found oviposition stimulation by mating and have suggested that it is the result of male strategies to increase short-term male reproductive success at some cost to females. The evolutionary scenario of our model organism seems to be quite different since females benefit greatly from increasing egg laying when there are conspecifics, because the advantages in terms of offspring survival are likely to translate into substantial increases in female reproductive success.
The evolution of egg carrying in Phyllomorpha laciniata (Het., Coreidae): a behavioural, physiological and molecular approach to explain its adaptive significance in males and females
Garcia-Gonzalez, F. & Ornosa, C. 2002 The evolution of egg carrying in Phyllomorpha laciniata (Het., Coreidae): a behavioural, physiological and molecular approach to explain its adaptive significance in males and females PhD Thesis, Complutense University of Madrid