G. Machado

G. Machado
University of São Paulo | USP · Institute of Bioscience (IB) (São Paulo)

About

178
Publications
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3,713
Citations
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January 2007 - present
University of São Paulo
Position
  • Professor (Associate)

Publications

Publications (178)
Article
Full-text available
The origin of parental care is a central question in evolutionary biology, and understating the evolution of this behaviour requires quantifying benefits and costs. To address this subject, we conducted a meta-analysis on amphibians, a group in which parental care has evolved multiple times. We found that both male and female parents increase egg s...
Article
Full-text available
Intraspecific weapon polymorphisms that arise via conditional thresholds may be affected by juvenile experience such as predator encounters, yet this idea has rarely been tested. The New Zealand harvestman Forsteropsalis pureora has three male morphs: majors (alphas and betas) are large-bodied with large chelicerae used in male–male contests, while...
Article
Describing the signals involved in sexual interactions is crucial to understand how mating and fertilization success is achieved. We analyzed sexual interactions in the gonyleptid harvestman Pachyloides thorellii Holmberg, 1878 to test the possibility of associations between female and male behaviors. For that purpose, we recorded 21 sexual interac...
Article
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In this review, we report on harvestmen and spiders feeding on fungi, fruits, and seeds. Fungivory in harvestmen is widespread, with most reports referring to tropical species in the family Sclerosomatidae, which consume mainly small forest mushrooms (families Marasmiaceae and Mycenaceae). In contrast, consumption of fungal material by spiders appa...
Article
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Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21 st century. The publication of the book Harvestmen: The Biology of Opiliones in 2007 stimulated development of many behavioral studies. Although the book is relatively recent, our understanding of the reproductive biology of harvestmen i...
Article
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Animal contests involve threatening displays and physical coercion, which are respectively performed by threat devices used in mutual evaluation of size or strength, and weapons used for grasping, stabbing, striking, or dislodging a rival. According to the functional allometry hypothesis, directional selection consistently favors hyper-allometry in...
Article
1. Multimodal communication may evolve because different signals may convey information about the signaller (content-based selection), increase efficacy of signal processing or transmission through the environment (efficacy-based selection), or modify the production of a signal or the receiver’s response to it (inter-signal interaction selection)....
Chapter
Male dimorphism is an emblematic example of disruptive selection, commonly found in arthropods. However, few studies compared pre-copulatory and copulatory courtship between morphs. Our review shows that pre-copulatory courtship may be markedly different between morphs. Four processes may explain these differences: only one morph expresses traits u...
Article
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The concept of mimicry has been developed for animals, but it also applies to plants. Plant species may be Müllerian mimics if they have similar reproductive traits and offer similar rewards to the pollinators. Several Oncidiinae orchids offer floral oils to their pollinators and have been suggested to form a Müllerian complex with species of Malpi...
Article
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Many animals form aggregations with individuals of the same species (single-species aggregations, SSA). Less frequently, individuals may also aggregate with individuals of other species (mixed-species aggregations, MSA). Although the benefits and costs of SSA have been intensively studied, the same is not true for MSA. Here, we first review the cas...
Article
A description of the pattern of structure and organization of the penial macrosetae was recently put forward for Gonyleptoidea Sundevall, 1833 and demonstrated to occur also in other families of Grassatores Kury, 2002, such as Assamiidae Srensen, 1884, Epedanidae Srensen, 1886 and Pyramidopidae Sharma, Prieto & Giribet, 2011. This set of homology h...
Article
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Background When males are selective, they can either reject low-quality females or adjust their reproductive investment in response to traits that indicate female quality (e.g., body size or condition). According to the differential allocation hypothesis , males increase their reproductive investment when paired with high-quality females ( positive...
Article
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In many taxa, individuals voluntarily detach a body part as a form to increase their chances of escaping predation. This defense mechanism, known as autotomy, has several consequences, such as changes in locomotor performance, that may affect fitness. Scorpions of the genus Ananteris autotomize the ‘tail’, which in fact corresponds to the last abdo...
Article
Intense sexual selection on males may drive the evolution of exaggerated weaponry, typically used in contests for females or reproductive sites. In some species, males have discontinuous variation in weapon morphology that is accompanied by alternative reproductive tactics (ARTs). Major males with enlarged weapons usually exhibit a mating tactic ba...
Article
In scramble competition mating systems, males do not guard females and females usually mate polyandrously, leading to high levels of sperm competition. Mathematical models predict that males facing sperm competition can either decrease or increase their reproductive effort. To test how male reproductive responses vary according to sperm competition...
Article
Full-text available
In many species, sexual dimorphism increases with body size when males are the larger sex but decreases when females are the larger sex, a macro-evolutionary pattern known as Rensch's rule (RR). Although empirical studies usually focus exclusively on body size, Rensch's original proposal included sexual differences in other traits, such as ornament...
Article
Nest‐site selection is a crucial decision made by parents because inadequate sites may expose the offspring and the parent to harsh abiotic and biotic conditions. Although nest‐site selection has been reported for some species of arthropods, the proximate cues used by parents to select the nest site and the adaptive meaning of nest‐site selection a...
Article
The ability to detach a body part in response to a predation attempt is known as autotomy, and it is perhaps the most intensively studied form of nonlethal injury in animals. Although autotomy enhances survival, it may impose reproductive costs on both males and females. We experimentally investigated how autotomy affects the reproductive success o...
Article
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Pre-maturation social experiences may affect post-maturation reproductive strategies of females, including mating preferences and investment in offspring. Whether pre-maturation social experiences affect other aspects of females’ reproductive strategies, including the number of accepted males and post-copulatory decisions, is still an open question...
Article
Predation success depends on factors such as hunger, prey size, prey availability and intensity of competition. A neglected factor that may also influence predation success is the proper function of morphological traits related to prey search, capture and manipulation. Injuries that compromise the functionality of these morphological traits may red...
Article
Females from the same population usually have phenotypic variation in their mating preferences. However, the effects of this within‐population variation on the sexual selection acting on males are still unclear. We used‐individual based models to explore how within‐population variation in female preference (i.e., which male trait value is preferred...
Preprint
Full-text available
1. Many animal species communicate using multimodal signals, which are composed of two or more components emitted and interpreted through different sensory modalities. The main types of selective pressures leading to the evolution of multimodal signals are: (1) content-based, when combined components convey information about the signaller, (2) effi...
Preprint
Full-text available
The pre-maturation social environment experienced by females may affect their post-maturation reproductive strategies, including mating preferences and investment in offspring. Whether the pre-maturation social environment also affects other aspects of females’ reproductive strategies, such as the degree of polyandry and post-copulatory decisions,...
Article
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In nest-building species, offspring survival and reproductive success of parental individuals are strongly influenced by nest quality. Thus, quantifying the influence of abiotic conditions on nest integrity is important to predict the effects of weather variability on the fitness of parental individuals. Here, we investigated how rainfall affects n...
Chapter
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Article
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The evolution of exclusive paternal care in arthropods is influenced by both natural and sexual selection. Male care may simultaneously increase egg protection against natural enemies and male attractiveness to ovipositing females. When caring males desert or die, their clutches may be adopted either by females that provide flexible compensation of...
Preprint
Full-text available
The intensity of biotic interactions varies around the world, in such a way that mortality risk imposed by natural enemies is usually higher in the tropics. A major role of offspring attendance is protection against natural enemies, so the benefits of this behaviour should be higher in tropical regions. We tested this macroecological prediction wit...
Article
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When two mating tactics can be successfully used by different-sized males, disruptive selection may favour morphological divergence between males, resulting in intrasexual dimorphism. Here we characterize intrasexual dimorphism based on cheliceral size in males of the harvestman Paecilaemula lavarrei. We also describe how males of the two morphs us...
Article
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Many spectacular cases of biological diversity are associated with sexual selection, and structures under sexual selection often show positive static allometry: they are disproportionately large for the size of the animal’s body in larger individuals. Other sexually selected structures, however, show negative allometry or isometry. Theory fails to...
Article
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Lomanius annae sp. nov. is described from southern Vietnam. The species is characterized by the greatly developed dorso-basal process on cheliceral hand of males and by the partial effacement of all mesotergal grooves. The genus Lomanius contains four generic synonyms and currently comprises eight valid species distributed in China, Java, peninsula...
Article
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Mate searching is assumed to be performed mostly by males, but when females benefit from multiple mating or are under risk of failing to mate, they may also perform mate searching. This is especially important in scramble competition polygynies, in which mate searching is the main mechanism of mate competition. Typically, more mobile individuals ar...
Article
Full-text available
Males of several harvestman species fight for the possession of oviposition sites. Usually, males use spines and elongated appendages as weapons in these fights. Although males of many cranaids have spines that could be used as weapons, there is no report of male-male fights in this family. Here we describe the first case of a male-male fight in cr...
Article
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In a recent paper, Sharma et al. (2017) tested the hypothesis that eggs attached to males' legs in podoctid harvestmen are laid by conspecifics. Using molecular methods, they falsify the "paternal care hypothesis" and suggest that the eggs belong to spiders. Here we raise several criticisms to the authenticity of this finding and present arguments...
Poster
Full-text available
How efficient is paternal care against egg predation in a tropical rainforest? Since females remain in the vicinity of the nests, do they help caring for the eggs?
Article
Full-text available
Mate sampling, whereby individuals cannot access all potential mating partners in a population, is a ubiquitous yet poorly explored process. Ignoring mate sampling may underestimate female choice because the smaller the sample taken by individuals of the choosing sex, the weaker the correlation between sexually selected traits and the mating succes...
Article
Full-text available
Egg attendance is the most common and phylogenetically widespread form of post-ovipositional care among ectotherms. The main benefit of egg attendance is to enhance offspring survival by preventing or attenuating attacks from natural enemies. In arachnids, there are few experimental studies on the benefits of egg attendance, and they pertain to spe...
Article
Full-text available
The intensity of biotic interactions varies around the world, in such a way that mortality risk imposed by natural enemies is usually higher in the tropics. A major role of offspring attendance is protection against natural enemies, so the benefits of this behaviour should be higher in tropical regions. We tested this macroecological prediction wit...
Article
When there is a temporal trade-off between mating effort and parental care, theoretical models predict that intense sexual selection on males leads to reduced paternal care. Thus, high-quality males should invest more in mating effort because they have higher chances of acquiring mates, whereas low-quality males should bias their investment toward...
Article
Full-text available
Abiotic factors exert direct and indirect influences on behavioral, morphological, and life-history traits. Because some of these traits are related to reproduction, there is a causal link between climatic conditions and the expression of reproductive traits. This link allows us to generate predictions on how reproductive traits vary in large geogr...
Article
The expression of costly traits often depends on the amount of food available to the individuals. Chemical defenses are costly, thus their production should be condition-dependent. Here, we tested the hypothesis that an increase in food availability and an acetate-supplemented diet will increase the production of chemical defenses by the harvestman...
Article
Full-text available
Egg attendance imposes costs on parents, including decreased food intake and increased mortality risks. By concentrating parental activities when egg predation is greater and abiotic conditions are less stressful, parents may decrease these costs. Here, we quantify the costs and benefits of temporary egg desertion in the frog Thoropa taophora, whos...
Article
Full-text available
Many animal taxa that display sexual size dimorphism (SSD) exhibit a positive allometric relationship in which the degree of dimorphism increases with body size. This macroevolutionary pattern is known as Rensch's rule. Although sexual selection is hypothesized to be the main mechanism causing this pattern, body size is influenced by several select...
Article
Full-text available
The handicap principle proposes that sexual signals must be costly to be honest. Honesty may be maintained by the costs paid by honest signallers or by the potential costs of cheating. In the latter, handicaps should emerge as a consequence of speci c biological constraints, such as life-history trade-o s. Nuptial prey-giving arthropods are good sy...
Article
The availability and spatial distribution of reproductive resources determine female distribution, thus affecting the organization of mating systems and the intensity of sexual selection. Females of the harvestman Serracutisoma proximum lay eggs on specific plant species, which are defended by males of the large morph (majors). After oviposition, f...
Article
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Female investment in large eggs increases the demand for fatty acids, which are allocated for yolk production. Since the biosynthetic pathway leading to fatty acids uses the same precursors used in the formation of polyketides, allocation trade-offs are expected to emerge. Therefore, egg production should constrain the investment in chemical defens...
Chapter
Full-text available
Harvestmen belong to the order Opiliones , and, unlike other arachnids, they are highly polygynandrous , with both males and females mating multiply throughout the breeding season. In this chapter, we review the current information on sexual selection in the group, focusing mostly on intersexual interactions. Particularly, we provide an overview of...
Article
The expected quality of paternal behavior can influence female mating decisions and determine male mating success. We evaluated the importance of oviposition site quality, male body size, parental status (presence vs. absence of eggs under males’ protection), and time invested in care (less vs. more than 1 month) for male mating success in the harv...
Article
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Alternative mating tactics are common among species exhibiting resource defense polygyny. While large territorial males aggressively defend harems, small sneaker males generally invade these harems to mate furtively. The result is a sexual network that provides information on the sperm competition intensity (SCI) faced by males of both morphs. Here...
Article
Nest-related behaviors may benefit males by increasing offspring survival and their attractiveness to females, but may also limit males’ foraging activity, increase their metabolic expenses, and expose them to increased mortality during nest attendance. Although intensively studied among birds and ectothermic vertebrates, the costs of nest-related...
Article
Full-text available
Egg predation is the one of the main costs of brood desertion in many ectothermic animals. When stressful environmental conditions constrain parental activities to only some periods of the day, the combination of physical or chemical defenses may attenuate the costs related to egg loss during periods of temporary parental absence. Females of the ha...
Article
Secondary sexual traits increase male fitness, but may be maladaptive in females, generating intralocus sexual conflict that is ameliorated through sexual dimorphism. Sexual selection on males may also lead some males to avoid expenditure on secondary sexual traits and achieve copulations using alternative reproductive tactics (ARTs). Secondary sex...
Chapter
Exclusive paternal care is probably the rarest form of post-zygotic parental investment in nature. In arthropods, this behavior has independently evolved in 15 lineages, including approximately 1,500 species. Here, we review the theoretical background for the evolution of parental investment and sex roles, contrasting classical views with the most...
Chapter
Harvestmen (Arachnida: Opiliones) are a highly diverse group found in extremely different environmental conditions. For this and other reasons described in this chapter, they offer a novel and unique opportunity to explore hypotheses regarding the effect of abiotic environmental conditions on several life-history traits, and thus on their mating sy...
Chapter
The exuberant variety of neotropical life forms has lured naturalists for centuries. Darwin himself was amazed by this diversity, and among the first to suggest that many of their traits were not the result of natural (viability) selection but rather of an additional and sometimes opposite selective force: sexual selection. Does this imply that sex...
Article
Full-text available
The large Neotropical family Gonyleptidae comprises nearly 820 species divided into 16 subfamilies. The majority of publications on harvestman ecology, behaviour and scent gland secretion chemistry have focused on this family. We used the information available in the literature and combined it with an intensive search for ecological, behavioural an...
Article
Full-text available
Arthropods produce a great variety of natural compounds, many of which have unexplored biosynthesis. Among the armored harvestmen (Arachnida: Opiliones) of the suborder Laniatores, the defensive gland exudates contain vinyl ketones and other constituents of supposed polyketide origin. We have studied the biosynthesis of 1-hepten-3-one in the Neotro...