Reproductive expenditure affects utilisation of thorax resources in male Pieris napi butterflies (original) (raw)
Related papers
Functional Ecology, 2006
One route to a deeper understanding of the life history of organisms is to identify how resources are acquired and used for reproduction. This may be particularly relevant for insects such as nectar-feeding butterflies, which change diets during the life cycle. 2. Nitrogenous resources used for reproduction in nectar-feeding butterflies come principally from the juvenile diet and are stored in abdominal reserves. Juvenile resources are also used to build the soma of the adult. Consequently somatic and reproductive investment will trade off and constrain the amount of resources available for egg and spermatophore production. Recent findings show a pronounced decrease in thorax resource content and suggest that nitrogen from somatic tissue can be reallocated to reproduction and thus alleviate the resource limitation upon reproduction. 3. In this paper we test the prediction that the observed decrease in thorax nitrogen content is related to the expenditure of resources in spermatophore production in Pieris napi males. By comparing thorax nitrogen content over the life span between males mated 0 -3 times, we show that mating history is an important factor in explaining the observed decrease in nitrogen content. 4. These results support the hypothesis that thoracic resources are used for reproduction in male nectar-feeding butterflies.
Biological Journal of The Linnean Society, 2005
In nectar-feeding butterflies, reproductive potential is usually thought to depend on the size of the reproductive reserves in the abdomen, the adult food quality and, for females, the amount of resources received in the spermatophores at mating. Recent findings show that thorax mass and nitrogen content decrease with age in some butterfly species, and that thorax resources may be used for reproduction in the butterfly Pieris napi , just as in some other insects. In order to determine whether this is a general pattern and ascertain how it relates to the investment of resources in reproduction we studied the dynamics of thorax and abdomen mass changes in 11 Swedish butterfly species. By regressing thorax and abdomen mass on age of field-collected specimens, we show that loss of mass from both the thorax and the abdomen is a common phenomenon among nectar-feeding temperate zone butterflies under natural conditions. We argue that our results indicate that resources from flight muscles can be reallocated to reproduction by these butterflies, thus increasing their reproductive potential. Within species, females use proportionately more resources from the thorax than do males, as expected from the difference in investment of resources in reproduction. Among males we expect species with a higher reproductive investment to have a larger decrease in thorax and abdomen mass, and our data indicate that this is the case. Looking at the change in relative thorax mass, our results suggest that the use of resources from the thorax does not affect flight performance negatively, something that could constrain the use of muscle resources.
Protein content of spermatophores and male investment strategies in nectar-feeding butterflies
1996
The objective of this thesis was to investigate how male investment in ejaculates, both in terms of nutritional quality and sperm content, varies with the mating system in nectar-feeding butterflies. Protein content was determined using a dye-binding protein assay (Bio-Rad), and used as a measure of ejaculate quality. A comparative study on 11 species of butterflies from 2 genera was conducted to examine how male nutrient investment varied with female mating frequency (polyandry). Male ability to produce more than one large nutritious ejaculate was evaluated using three species of pierid that varied in the degree of polyandry. The cost of ejaculate production, in terms of recuperation time, was investigated in Pieris napi and Pieris rapae, two polyandrous species of pierid. Lastly, the effect of male body size on sperm precedence was examined using P. napi. I found that relative to males in monandrous systems, males in polyandrous systems transferred larger first ejaculates that con...
Protein content of spermatophores in relation to monandry/polyandry in butterflies
Behavioral Ecology and Sociobiology, 1995
The evolution of a mating system, and specifically mating frequency, is dependent on the costs and benefits to both sexes of mating once or several times. In butterflies, males transfer a spermatophore that contains both sperm and accessory gland products. Accessory gland substances contain nutrients which, in some species, females use to increase their reproductive output and longevity. Nutrients contained in these packaged ejaculates represent investment by males in reproduction. Consequently, the nutritional composition of spermatophores may vary depending on the mating system. There are two lines of arguments concerning the evolution of the nutrient content of ejaculates. One hypothesis argues that male nuptial gifts evolved in the context of certainty of paternity and ease of finding mates; thus spermatophores of polyandrous males (with lower certainty of paternity and greater ease of finding mates) should contain less protein than those of monandrous males, since more spermatophores are produced on average. The other hypothesis argues that polyandry evolved in the context of maximization of male transfer of nutrients to females, and hence spermatophores of polyandrous males should contain more protein than those of monandrous males. In an attempt to distinguish between these two hypotheses, we determined how protein content of ejaculates varied with the degree of polyandry in nine species of pierid and two species of satyrid butterflies. We found that both relative ejaculate mass and protein content increased with the degree of polyandry. Hence our results are consistent with the view that polyandry has evolved in the context of male transfer of nutrients to females, and provides another example of a male adaptation to multiple mating in butterflies.
Behavioral Ecology and Sociobiology, 1988
In many insects nutrients transferred by the male at mating are later incorporated into both the eggs and soma of the mated females. Accordingly, it has been suggested that insect females can use these male-derived nutrients for somatic maintenance and enhancement of their fecundity and fitness of their offspring. In this paper we tested the validity of these predictions by studying the longevity and reproductive output of 1, 2, 3, 4 or 5 times mated female monarchs Danaus plexippus, a nectar-feeding butterfly that is long-lived and strongly polyandrous and emerges as an adult without mature eggs. Females mated five times received ejaculates that corresponded to an average of 38% of their body weight at eclosion. However, we found that the number of times females had mated had no effect on their longevity, life-time fecundity, or egg weight. Although negative evidence should always be interpreted with caution, our study suggests that male-derived nutrients are less important for female longevity and reproductive output than are larval and adult food.
Paternal investment directly affects female reproductive effort in an insect
Proceedings. Biological sciences / The Royal Society, 2003
Female reproductive effort can be influenced by the quality of her mate. In some species, females increase their reproductive effort by differentially allocating resources after mating with high-quality males. Examination of female reproductive effort in relation to male quality has implications for estimating the evolvability of traits and for sexual-selection models. Accurate quantification of reproductive investment is not possible in many species. Butterflies are an exception, as most nectar-feeding species emerge with almost intact reproductive resources, and in some species males provide nutrients at mating that enhance female fecundity. By manipulating male donations and using radioactive isotopes, we quantified the effect of variation in nutrient provisioning on female reproductive effort in two butterfly species. In the greenveined white butterfly, Pieris napi, females increased their reproductive effort after receiving large male donations. By contrast, in the speckled woo...
Strategic sperm allocation in the Small White butterfly Pieris rapae (Lepidoptera: Pieridae)
Functional Ecology, 1999
In species where females mate multiply, it is important for males to recuperate quickly in order to maximize their fertilization success. Butterflies produce a spermatophore at mating containing accessory secretions and sperm of two types: a large number of nonfertile 'apyrene' sperm and fewer fertile 'eupyrene' sperm. Many butterfly species eclose with most nutrients for reproduction already present. Males must therefore decide how to allocate resources to the various spermatophore components at any given mating. 2. Recovery rates of apyrene and eupyrene sperm number and spermatophore size was studied in the polyandrous Small White butterfly Pieris rapae. The mass of the first spermatophore increases with time since eclosion, as does the number of both types of sperm. Similarly, on a male's second mating, both the mass of the spermatophore and the number of sperm increases with time since the first mating. 3. However, the rate of increase in eupyrene sperm numbers is higher after the first mating. The difference in rate of increase may be the result of different probabilities of virgin and non-virgin males obtaining future matings. 4. Males have a sperm storage organ, the duplex, in which they retain sperm after their first mating. This ensures that high sperm numbers are available for their second mating, even when remating only 1 h later. Thus, males do not ejaculate all available sperm on any given mating, and seem to have different strategies on their first and second matings. 5. It can be argued that Small White butterfly males allocate sperm strategically according to the probability of obtaining subsequent matings, and the level of sperm competition.
Allocation of larval and adult resources to reproduction in a fruit-feeding butterfly
Functional Ecology, 2004
1. The source of nutritional resources allocated to reproduction strongly influences reproductive and foraging strategies. While we are beginning to understand the role of adult and larval resources for nectivorous Lepidoptera, essentially nothing is known for the large number of species that feed on fruit as adults. 2. We used stable isotopes to examine allocation of larval-and adult-derived resources to egg production in a tropical frugivorous butterfly, Bicyclus anynana (Butler, 1879), under both ad libitum and semistarvation conditions. The butterfly's larval and adult host plants differ from each other in both carbon and nitrogen isotopic ratios. 3. Adult fruit feeding is required for the onset of oviposition. 4. At peak, adult fruit feeding contributed 55% of the carbon found in eggs under both feeding conditions. This is similar to values for several nectivorous Lepidoptera with similar ovarian dynamics and egg C/N. 5. Egg 15 N declined rapidly during the first week of oviposition, suggesting that the adult diet was not contributing nitrogen to egg production. Values rose during the following 2 weeks, consistent either with adult contribution or with isotopic fractionation. 6. Our results are consistent with the hypothesis that fruit serves as a carbon source for egg production in a similar manner as nectar. However, more work is needed to elucidate fully fruit's role as a nitrogen source.