Characterizing the interaction between the bogus yucca moth and yuccas: do bogus yucca moths impact yucca reproductive success?

Yucca moths are most well known for their obligate pollination mutualism with yuccas, where pollinator moths provide yuccas with pollen and, in exchange, the moth larvae feed on a subset of the developing yucca seeds. The pollinators, however, comprise only two of the three genera of yucca moths. Members of the third genus, Prodoxus, are the bogus yucca moths and are sister to the pollinator moths. Adult Prodoxus lack the specialized mouthparts used for pollination and the larvae feed on plant tissues other than seeds. Prodoxus larvae feed within the same plants as pollinator larvae and have the potential to influence yucca reproductive success directly by drawing resources away from flowers and fruit, or indirectly by modifying the costs of the mutualism with pollinators. We examined the interaction between the scape-feeding bogus yucca moth, Prodoxus decipiens, and one of its yucca hosts, Yucca filamentosa, by comparing female reproductive success of plants with and without moth larvae. We determined reproductive success by measuring a set of common reproductive traits such as flowering characteristics, seed set, and seed germination. In addition, we also quantified the percent total nitrogen in the seeds to determine whether the presence of larvae could potentially reduce seed quality. Flowering characteristics, seed set, and seed germination were not significantly different between plants with and without bogus yucca moth larvae. In contrast, the percent total nitrogen content of seeds was significantly lower in plants with P. decipiens larvae, and nitrogen content was negatively correlated with the number of larvae feeding within the inflorescence scape. Surveys of percent total nitrogen at three time periods during the flowering and fruiting of Y. filamentosa also showed that larval feeding decreased the amount of nitrogen in fruit tissue. Taken together, the results suggest that although P. decipiens influences nitrogen distribution in Y. filamentosa, this physiological effect does not appear to impact the female components of reproductive success.     

Pollinator attraction to volatiles from virgin and pollinated host flowers in a yucca/moth obligate mutualism

The classic obligate pollination–seed consumption mutualism between yuccas and yucca moths has been thought to be mediated by chemical cues, but empirical data on pollinator attraction to host floral volatiles in this association have been lacking. Here we show that the scent from virgin flowers of the host Yucca glauca is sufficient to attract its obligate pollinator Tegeticula yuccasella in Y‐tube olfactometer tests. Interestingly, both sexes of moths were attracted to the scent stimulus. Because yucca moths mate inside host flowers, the attraction of both females and males to host floral volatiles is likely to increase encounter rates. In a second test, female moths did not discriminate between virgin and hand‐pollinated flowers, indicating no post‐pollination change in scent production by the host that would lead to a reduction in pollinator attraction and thereby limit exploitation of the available seeds in host flowers. However, other mechanisms that could stabilise the mutualism between T. yuccasella and its yucca hosts have already been documented, i.e. selective abortion of heavily infested flowers, and a female‐derived host‐marking pheromone. Headspace collection and GC–MS were used to identify the blend of floral volatiles emitted by Y. glauca, which was found to be very similar to those of two other allopatric capsular‐fruited species, Y. elata and Y. filamentosa, revealing strong conservation of this trait within Yucca section Chaenocarpa.     

Pollen dispersal in Yucca filamentosa (Agavaceae): the paradox of self-pollination behavior by Tegeticula yuccasella (Prodoxidae)

We investigated pollen dispersal in an obligate pollination mutualism between Yucca filamentosa and Tegeticula yuccasella. Yucca moths are the only documented pollinator of yuccas, and moth larvae feed solely on developing yucca seeds. The quality of pollination by a female moth affects larval survival because flowers receiving small amounts of pollen or self-pollen have a high abscission probability, and larvae die in abscised flowers. We tested the prediction that yucca moths primarily perform outcross pollinations by using fluorescent dye to track pollen dispersal in five populations of Y. filamentosa. Dye transfers within plants were common in all populations (mean ± 1 SE, 55 ± 3.0%), indicating that moths frequently deposit self-pollen. Distance of dye transfers ranged from 0 to 50 m, and the mean number of flowering plants between the pollen donor and recipient was 5 (median = 0), suggesting that most pollen was transferred among near neighbors. A multilocus genetic estimate of outcrossing based on seedlings matured from open-pollinated fruits at one site was 94 ± 6% (mean ± 1 SD). We discuss why moths frequently deposit self-pollen to the detriment of their offspring and compare the yucca-yucca moth interaction with other obligate pollinator mutualisms in which neither pollinator nor plant benefit from self-pollination.     

How to become a yucca moth: minimal trait evolution needed to establish the obligate pollination mutualism

The origins of obligate pollination mutualisms, such as the classic yucca–yucca moth association, appear to require extensive trait evolution and specialization. To understand the extent to which traits truly evolved as part of establishing the mutualistic relationship, rather than being pre‐adaptations, we used an expanded phylogenetic estimate with improved sampling of deeply‐diverged groups to perform the first formal reconstruction of trait evolution in pollinating yucca moths and their nonpollinating relatives. Our analysis demonstrates that key life‐history traits of yucca moths, including larval feeding in the floral ovary and the associated specialized cutting ovipositor, as well as colonization of woody monocots in xeric habitats, may have been established before the obligate mutualism with yuccas. Given these pre‐existing traits, novel traits in the mutualist moths are limited to the active pollination behaviours and the tentacular appendages that facilitate pollen collection and deposition. These results suggest that a highly specialized obligate mutualism was built on the foundation of pre‐existing interactions between early Prodoxidae and their host plants, and arose with minimal trait evolution. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 847–855.     

Effect of pollinator-inflicted ovule damage on floral abscission in the yucca-yucca moth mutualism: the role of mechanical and chemical factors

The long-term persistence of obligate mutualisms (over 40 Mya in both fig/fig wasps and yucca/yucca moths) raises the question of how one species limits exploitation by the other species, even though there is selection pressure on individuals to maximize fitness. In the case of yuccas, moths serve as the plant's only pollinator, but eggs laid by the moths before pollination hatch into larvae that consume seeds. Previous studies have shown that flowers with high egg loads are more likely to abscise. This suggests that yucca flowers can select against moths that lay many eggs per flower through selective abscission of flowers; however, it is not known how yucca moths trigger floral abscission. We tested how the moth Tegeticula yuccasella triggers floral abscission during oviposition in Yucca filamentosa by examining the effects of ovipositor insertion and egg laying on ovule viability and floral abscission. Eggs are not laid at the site of ovipositor insertion: we used this separation to test whether wounded ovules were more closely associated with the ovipositor site or an egg's location. Using a tetrazolium stain to detect injured ovules, we determined whether the number of ovipositions affected the number of wounded ovules in naturally pollinated flowers. Two wounding experiments were used to test the effect of mechanical damage on the probability of floral abscission. The types of wounds in these experiments mimicked two types of oviposition-superficial oviposition in the ovary wall and oviposition into the locular cavity-that have been observed in species of Tegeticula. The effect of moth eggs on ovule viability was experimentally tested by culturing ovules in vitro, placing moth eggs on the ovules, and measuring changes in ovule viability with a tetrazolium stain. We found that ovules were physically wounded during natural oviposition. Ovules showed a visible wounding response in moth-pollinated flowers collected 7-12 h after oviposition. Exact location of wounded ovules relative to eggs and oviposition scars, as well as results from the artificial wounding experiments, showed that the moth ovipositor inflicts mechanical damage on the ovules. Significantly higher abscission rates were observed in artificially wounded flowers in which only 4-8% of the ovules were injured. Eggs did not affect ovule viability as measured by the tetrazolium stain. These results suggest that physical damage to ovules caused by ovipositing is sufficient to explain selective fruit abscission. Whether injury as a mechanism of selective abscission in yuccas is novel or a preadaptation will require further study.     

Re-evaluating the role of selective abscission in moth/yucca mutualisms

Conflicts of interest are common to mutualisms, particularly those derived from exploitative interactions. Conflicts of interest are particularly pronounced in pollination/seed predation mutualisms, such as moth/yucca interactions, where consumption of seeds by larvae of a plant's pollinator will raise the fitness of the pollinator but lower the fitness of the plant. A central question in these mutualisms is, therefore, “what limits seed predation?” If plants with excess flowers selectively abscise flowers containing many eggs, they may reduce seed predation and overall increase their fecundity. If eggs in abscised flowers die, selective abscission may additionally contribute to the limitation or regulation of pollinator populations, thereby decreasing the probability of future overexploitation. We examined the effect of selective abscission in the mutualism between Yucca kanabensis and one of its pollinating moths, Tegeticula altiplanella. Per capita mortality of moth eggs due to abscission was high (95.5%), but did not increase on inflorescences with more ovipositions per flower. Overall mortality was partitioned into two components based upon the proportion of visited flowers abscised (i.e. resource‐limitation) and additional mortality (=selective abscission). Resource‐limitation per se inflicted 93.9% egg mortality, or most of the mortality due to abscission. But, the average number of eggs in fruit was lower than the average number of eggs in flowers, indicating that there was some selectivity of abscission. However, neither source of mortality increased on inflorescences with more ovipositions per visited flower. Egg mortality resulting from selective abscission was not as high as possible, because the yuccas appeared to use oviposition‐damaged ovules as a cue for selective abscission, and there was considerable variation in the relationship between oviposition number and damaged ovules. However, even if yuccas had retained the flowers containing the fewest eggs, selective abscission still would not have been higher on inflorescences with more ovipositions per flower. Considering also that, 1) number of ovipositions is a poor predictor of the number of larvae that hatch and feed on the developing seeds in a fruit and that, 2) there are several moth/yucca interactions in which selective abscission does not occur, we conclude that abscission, and particular selective abscission, may have density‐limiting effects on moth populations, but will fail as general explanations for regulating the dynamics of moth populations.     

传粉甲虫的研究进展

许多鞘翅目甲虫是重要的传粉昆虫 ,在漫长的历史进化过程中伴随着一系列的相互适应的形成 ,很多甲虫与花之间建立了固定的传粉关系。该文从甲虫与花之间传粉的相互适应、传粉甲虫的类群、甲虫传粉的植物和甲虫传粉效果等 4方面做了简要综述。     

Limiting the costs of mutalism: multiple modes of interaction between yuccas and yucca moths

In pollination–seed predation mutualisms between yuccas and yucca moths, conflicts of interest exist for yuccas, because benefits of increased pollination may be outweighed by increased seed consumption. These conflicts raise the problem of what limits seed consumption, and ultimately what limits or regulates moth populations. Although the current hypothesis is that yuccas should selectively abscise flowers with high numbers of yucca-moth eggs, within-inflorescence selective abscission occurs in only one of the three moth–yucca systems that we studied. It occurs only when oviposition directly damages developing ovules, and does not, therefore, provide a general explanation for the resolution of moth–yucca conflicts. Within-locule egg mortality provides an alternative and stronger mechanism for limiting seed damage, and generating density-dependent mortality for yucca-moth populations. However, the most important feature of moth–yucca systems is that they are diverse, encompassing multiple modes of interaction, each with different consequences for limiting and regulating yucca moths.     

Facultative non-mutualistic behaviour by an “Obligate” mutualist: “Cheating” by Yucca moths

The interaction between yucca moths (Tegeticula spp., Incurvariidae) and yuccas (Yucca spp., Agavaceae) is an obligate pollination/seed predation mutualism in which adult female yucca moths pollinate yuccas, and yucca moth larvae feed on yucca seeds. In this paper we document that individual yucca moths, which are capable of acting as mutualists, facultatively cheat by ovipositing in yucca pistils without attempting to transfer pollen. Additionally, a high proportion of flowers are unlikely to receive pollen even when pollination is attempted, because many yucca moths carry little or no pollen. The probability of occurrence of non-mutualistic behaviour is not affected by the amount of pollen a moth carries: moths with full pollen loads are just as likely to act non-mutualistically as moths carrying little or no pollen. We propose four hypotheses that could explain facultative non-mutualistic behaviour in yucca moths.Present address: Department of Biology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada     

Limiting the success of stem borers (Prodoxus quinquepunctellus) in yuccas: indirect effects of ants, aphids, and fruit position

Abstract.  1. Although the moth–yucca mutualism is often studied as a pairwise interaction, yucca plants are also the sole host for a variety of other visitors. One of these additional visitors is a stem-boring moth, Prodoxus quinquepunctellus.
2. In this study, it is shown how the reproductive success of Prodoxus indirectly depends on the interactions between yuccas and their pollinators ( Tegeticula , Prodoxidae) as well as the indirect effects of ants and aphids.
3. Aggressive wood ants foraging on yuccas will attack adult Prodoxus moths while attempting to oviposit. This reduces the number of eggs laid in yucca stalks, leading to fewer larvae feeding in the stalks.
4. Once in the stalk, the survival of Prodoxus eggs/larvae depends upon the rate at which the flowering stalks dry out during fruit maturation. Portions of the stalk above the highest fruit dry out quickly and survivorship approaches zero in these dry sections, while larvae in green sections of the flowering stalk have significantly higher survival rates. The presence of aphids feeding on the stalk slows down the rate of stalk drying and could lead to increased survival of Prodoxus larvae.
5. Overall, ants have strong indirect effects on P. quinquepunctellus by controlling how many eggs are laid in the stalk and by influencing the distribution of aphids. However, it is primarily the presence and position of the fruit that can affect larval survivorship, and fruit position is a function of pollinator visits and resource limitation. These complex interactions illustrate the importance of studying the yucca–moth mutualism in a community context.     

Defection by plants in the yucca–yucca moth association: a test of the cheater plant hypothesis for Yucca treculeana

In mutualisms, an underlying conflict of interests may select for defection from providing benefits. In the obligate mutualism between yuccas and yucca moths, where pollination service and seeds for pollinator larvae are traded, it has been suggested that some individuals in a population of Y. baccata may defect by preventing pollinator egg or larvae from development. We tested this hypothesis in Y. treculeana , another species suggested to contain cheater plants. Five specific predictions were tested during two years of study. A prediction that a surplus of plants without pollinator larvae should be present was met. Predicted existence of two distinct fruit morphs was rejected, and none of several highly variable morphological traits were linked to presence/absence of larvae. Predicted excess of intact seeds in the fruits of plants without larvae was not found; in fact, such plants produced fewer seeds, contrary to the hypothesis. A suggestion that inverse frequency-dependent fitness could explain the pattern was rejected. Contrary to prediction, distribution of larvae of a closely related cheater yucca moth was positively associated with pollinator larvae, even though it would not be affected by the proposed killing mechanism. The results together provide strong support against the existence of cheater plants in Y. treculeana .     

Effects of florivory on floral volatile emissions and pollination success in the wild parsnip

In addition to reducing fitness by consuming reproductive structures, florivores may also reduce plant fitness by altering interactions with pollinators. To date, the effects of florivore activity on the volatile profile of flowers and subsequent attractiveness to pollinators have not been extensively investigated. In this study, we had three specific objectives: to determine the impact of florivory by the parsnip webworm Depressaria pastinacella on the floral volatile profile of the wild parsnip Pastinaca sativa, to ascertain the mechanisms by which florivory changes the volatile profile, and to estimate the consequences of florivory on visitation by pollinators and eventual seed set. An overall indirect effect of webworms on seed set, that is, the effect of infestation on pollination success, was not detected. However, this overall lack of indirect effect masks the heterogeneity among individual plants. For seven of 14 plants examined, pollination success was altered by webworms, and in four of these plants the alteration in pollination success was consistent with webworm-altered visitation. Webworms significantly altered floral fragrance, in particular causing disproportionate increases in the emissions of octyl esters. Additionally, volatiles from webworm frass, which contains large amounts of the octyl ester metabolite n-octanol, may alter the floral fragrance in ways that change attractiveness of flowers to pollinators. This study suggests that the effects of florivores on plant fitness are not limited to the removal of floral units but may also involve alterations in floral volatile composition, through damage-induced release and detoxification of particular constituents, that affect visitation and pollination success. Handling Editor: Steve Johnson. An erratum to this article can be found at     

Genetic consequences of specialization: yucca moth behavior and self-pollination in yuccas

Reciprocal specialization in interspecific interactions, such as plant-pollinator mutualisms, increases the probability that either party can have detrimental effects on the other without the interaction being dissolved. This should be particularly apparent in obligate mutualisms, such as those that exist between yucca and yucca moths. Female moths collect pollen from yucca flowers, oviposit into floral ovaries, and then pollinate those flowers. Yucca moths, which are the sole pollinators of yuccas, impose a cost in the form of seed consumption by the moth larvae. Here we ask whether there also is a genetic cost through selfish moth behavior that may lead to high levels of self fertilization in the yuccas. Historically, it has been assumed that females leave a plant immediately after collecting pollen, but few data are available. Observations of a member of the Tegeticula yuccasella complex on Yucca filamentosa revealed that females remained on the plant and oviposited in 66% of all instances after observed pollen collections, and 51% of all moths were observed to pollinate the same plant as well. Manual cross and self pollinations showed equal development and retention of fruits. Subsequent trials to assess inbreeding depression by measuring seed weight, germination date, growth rate, and plant mass at 5 months revealed significant negative effects on seed weight and germination frequency in selfed progeny arrays. Cumulative inbreeding depression was 0.475, i.e., fitness of selfed seeds was expected to be less than half that of outcrossed seeds. Single and multilocus estimates of outcrossing rates based on allozyme analyses of open-pollinated progeny arrays did not differ from 1.0. The discrepancy between high levels of behavioral self-pollination by the moths and nearly complete outcrossing in mature seeds can be explained through selective foreign pollen use by the females, or, more likely, pollen competition or selective abortion of self-pollinated flowers during early stages of fruit development. Thus, whenever the proportion of pollinated flowers exceeds the proportion that can be matured to ripe fruit based on resource availability, the potential detrimental genetic effects imposed through geitonogamous pollinations can be avoided in the plants. Because self-pollinated flowers have a lower probability of retention, selection should act on female moths to move among plants whenever moth density is high enough to trigger abortion. Received: 18 March 1996 \Accepted: 30 July 1996     

The role of abiotic and biotic factors in determining coexistence of multiple pollinators in the yucca–yucca moth mutualism

The determinants of a species' geographic distribution are a combination of both abiotic and biotic factors. Environmental niche modeling of climatic factors has been instrumental in documenting the role of abiotic factors in a species' niche. Integrating this approach with data from species interactions provides a means to assess the relative roles of abiotic and biotic components. Here, we examine whether the high host specificity typically exhibited in the active pollination mutualism between yuccas and yucca moths is the result of differences in climatic niche requirements that limit yucca moth distributions or the result of competition among mutualistic moths that would co‐occur on the same yucca species. We compared the species distribution models of two Tegeticula pollinator moths that use the geographically widespread plant Yucca filamentosa. Tegeticula yuccasella occurs throughout eastern North America whereas T. cassandra is restricted to the southeastern portion of the range, primarily occurring in Florida. Species distribution models demonstrate that T. cassandra is restricted climatically to the southeastern United States and T. yuccasella is predicted to be able to live across all of eastern North America. Data on moth abundances in Florida demonstrate that both moth species are present on Y. filamentosa; however, T. cassandra is numerically dominant. Taken together, the results suggest that moth geographic distributions are heavily influenced by climate, but competition among pollinating congeners will act to restrict populations of moth species that co‐occur.     

Regulation of the mutualism between yuccas and yucca moths: intrinsic and extrinsic factors affecting flower retention

Yuccas initiate far more flowers than they can mature as fruit, thereby providing opportunities for them to mature flowers of the highest quality. Flower quality in yuccas has both intrinsic and extrinsic components. Intrinsic components relate to flower morphology and inflorescence architecture. Yucca moths (Tegeticula spp., Incurvariidae), the sole pollinators and primary seed predators of most yuccas (Yucca spp., Agavaceae), mediate extrinsic components of flower quality through their ovipositions in flowers, and the quantity and quality of pollen that they transfer. In addition, intrinsic and extrinsic components interact as a function of flowering phenology and moth activity within inflorescences.
We investigated selective abscission of flowers in Y. kanabensis with respect to various combinations of intrinsic and extrinsic factors. First, we considered the effect of high and low pollen loads delivered to different subsets of flowers and in different presentation orders. In the absence of moth ovipositions, Y. kanabensis is sensitive to the amount of pollen that moths deliver and tends to retain high pollen flowers, even when all flowers receive sufficient pollen for full fertilization. However, pollen delivery sequence and the position of flowers with an inflorescence modify this high pollen effect. We then considered the interplay between high and low pollen combined with moth ovipositions and found that the number of ovipositions dominated the pollen effect. Finally, we considered number of ovipositions in conjunction with different flowers in the blooming sequence while controlling pollen levels and found that the clear effect of ovipositions on flower fate can be tempered by where the flower is in the blooming sequence.
These results have implications for the regulation of the mutualism between yuccas and yucca moths, indicating that yuccas are capable of regulating costs, retaining flowers of relative high quality and selectively abscising the rest. Yucca sensitivity to several intrinsic and extrinsic factors allows the plant to respond flexibly to the pollination environment and several species of moths.     

Phylogeographic structure in the bogus yucca moth Prodoxus quinquepunctellus (Prodoxidae): comparisons with coexisting pollinator yucca moths

The pollination mutualism between yucca moths and yuccas highlights the potential importance of host plant specificity in insect diversification. Historically, one pollinator moth species, Tegeticula yuccasella, was believed to pollinate most yuccas. Recent phylogenetic studies have revealed that it is a complex of at least 13 distinct species, eight of which are specific to one yucca species. Moths in the closely related genus Prodoxus also specialize on yuccas, but they do not pollinate and their larvae feed on different plant parts. Previous research demonstrated that the geographically widespread Prodoxus quinquepunctellus can rapidly specialize to its host plants and may harbor hidden species diversity. We examined the phylogeographic structure of P. quinquepunctellus across its range to compare patterns of diversification with six coexisting pollinator yucca moth species. Morphometric and mtDNA cytochrome oxidase I sequence data indicated that P. quinquepunctellus as currently described contains two species. There was a deep division between moth populations in the eastern and the western United States, with limited sympatry in central Texas; these clades are considered separate species and are redescribed as P. decipiens and P. quinquepunctellus (sensu stricto), respectively. Sequence data also showed a lesser division within P. quinquepunctellus s.s. between the western populations on the Colorado Plateau and those elsewhere. The divergence among the three emerging lineages corresponded with major biogeographic provinces, whereas AMOVA indicated that host plant specialization has been relatively unimportant in diversification. In comparison, the six pollinator species comprise three lineages, one eastern and two western. A pollinator species endemic to the Colorado Plateau has evolved in both of the western lineages. The east-west division and the separate evolution of two Colorado Plateau pollinator species suggest that similar biogeographic factors have influenced diversification in both Tegeticula and Prodoxus. For the pollinators, however, each lineage has produced a monophagous species, a pattern not seen in P. quinquepunctellus.     

BREEDING STRUCTURE OF A YUCCA FILAMENTOSA (AGAVACEAE) POPULATION

Yucca filamentosa and its species-specific pollinator, the yucca moth, Tegeticula yuccasella (Lepidoptera: Prodoxidae), form a relationship that is often cited as a classic example of a coevolved plant-pollinator mutualism. Observations of the moth's behavior have led to predictions that moth dispersal is relatively limited and that, as a consequence, the self-compatible Y. filamentosa should experience relatively high rates of self-fertilization. In contrast, analyses of its mating system indicated that Y. filamentosa was predominantly outcrossed. To better understand effective breeding patterns in Y. filamentosa populations, 10 polymorphic allozyme loci were investigated to analyze the breeding structure of a natural Y. filamentosa population. Analyses revealed that Y. filamentosa is predominantly outcrossed, has multiply sired fruits, and that each fruit was sired by a different set of pollen donors. The effective number of pollen donors per fruit ranged from 1.56 to 3.13, indicating that some correlated mating exists within fruits. Paternity analyses revealed that pollen moved from 6 m to 293 m (mean = 118 m) within the study population and that a minimum of 10% of the progeny were sired by pollen originating outside of the population. These results are discussed in the context of the yucca–yucca moth mutualism.     

Coevolution and divergence in the Joshua tree/yucca moth mutualism

Theory suggests that coevolution drives diversification in obligate pollination mutualism, but it has been difficult to disentangle the effects of coevolution from other factors. We test the hypothesis that differential selection by two sister species of pollinating yucca moths (Tegeticula spp.) drove divergence between two varieties of the Joshua tree (Yucca brevifolia) by comparing measures of differentiation in floral and vegetative features. We show that floral features associated with pollination evolved more rapidly than vegetative features extrinsic to the interaction and that a key floral feature involved in the mutualism is more differentiated than any other and matches equivalent differences in the morphology of the pollinating moths. A phylogenetically based, ancestral states reconstruction shows that differences in moth morphology arose in the time since they first became associated with Joshua trees. These results suggest that coevolution, rather than extrinsic environmental factors, has driven divergence in this obligate pollination mutualism.     

Beetle pollination and flowering rhythm ofAnnona spp. (Annonaceae) in Brazil

Dynastid scarab beetles are the main or exclusive pollinators ofAnnona spp. with large flowers and wide floral chambers. These nocturnal beetles are attracted by the characteristic odours which are caused by measurable temperature elevation of the flowers up to 10°C or even 15°C above the ambient air temperature. TheAnnona spp. investigated showed different floral rhythms varying from one to three days. The elaborate and wellcoordinated flowering processes, along with floral heating and olfactorial attraction of the night-activeCyclocephala spp., result in a very precise and effective pollination. The floral chamber provides alimentation for the beetles in the form of nutritious food-tissues and pollen and offers a mating place and a well developed shelter against predation and environmental changes. A staggered flowering period and an alternative attraction of different beetle species seems to be more a device for diminishing competition between the cooccurringAnnona spp. than a hybridization barrier.     

RAD‐seq phylogenomics recovers a well‐resolved phylogeny of a rapid radiation of mutualistic and antagonistic yucca moths

The interaction between yucca plants and yucca moths has been one of the focal model systems investigated in the study of pollination mutualism and coevolution, especially in terms of understanding the prevention of overexploitation by mutualist partners. Yuccas have the ability to assess the number of eggs placed by pollinators into their ovaries, and can preferentially abort those flowers that would have many moth larvae consuming yucca seeds. Previous phylogenetic research identified a rapid radiation of moth species that corresponded with shifts in the interaction with their host plants. These shifts led to the evolution of moth species that circumvent the egg detection method used by yuccas to limit seed damage. In particular, some pollinator species deposit their eggs so that they are undetectable by the plants, whereas other species are ‘cheaters’ that have lost the ability to pollinate, yet deposit eggs into developing fruit rather than flowers. The evolution of these new species happened so quickly that the phylogeny of the moths has remained unresolved despite repeated attempts with standard Sanger sequencing of mtDNA loci and AFLP marker generation. Here, we use extensive analyses of RAD‐seq data to determine the phylogenetic relationships among yucca moth species. The results provide a robust phylogenetic framework that identifies the evolutionary relationships among shifts in egg‐laying strategies, as well as determining the closest pollinating relatives to the cheater species. Based on the obtained phylogeny, a shift in egg‐laying strategy that avoided the overexploitation regulatory mechanism used by yucca plants was a precursor for the evolution of two species with cheating behaviour.