Diversity Of Flowering Plants Research Articles

Contrasting effects of exotic plant invasions and managed honeybees on plant–flower visitor interactions

AbstractAimTo explore how a highly invasive plant species (Buddleja davidii Franch.), managed honeybees and flower diversity affected plant–flower visitor interactions over the whole elevational range distribution of the exotic plant.LocationItalian Alps.MethodsWe selected nine pairs of sites (one invaded and one non‐invaded by B. davidii) across gradients in honeybee abundance and diversity of flower resources. We observed plant–flower visitor interactions every three weeks, for a total of five surveys covering the full flowering season of B. davidii (June–August). We tested how B. davidii, honeybee abundance and flowering plant diversity affected network robustness, overlap in flower resource use of wild flower visitors with honeybees and flower visitor specialization. We also tested for an interaction between B. davidii presence and honeybee abundance, and tested whether the effects of the two variables changed among insect orders.ResultsBuddleja davidii and honeybees had contrasting effects on network robustness and on several species‐level metrics. Network robustness increased with increasing honeybee abundance and flower diversity. Increasing honeybee abundance generally increased specialization of lepidopterans and dipterans that tended to switch to less visited plant species, possibly in order to avoid competition. Specialization of flower visitors declined in sites invaded by B. davidii, indicating that the invasive plant attracted pollinators, which in turn also visited co‐occurring species in the neighbourhood.Main conclusionsAlthough increasing honeybee abundance was associated with higher network stability, it also modified plant–flower visitor interactions by forcing species to shift their diet irrespective of floral diversity. The effect was particularly strong for non‐bee flower visitors. The consequences of these changes in plant–flower visitor interactions for the reproductive success of flowering plants are still largely unknown.

Patterns of Symmetry Expression in Angiosperms: Developmental and Evolutionary Lability

Variation in flower symmetry is a remarkable aspect of flowering plant diversity. Multiple evolutionary transitions from an ancestral form of radial symmetry to bilateral symmetry and reversals from bilateral to radial symmetry have occurred during angiosperm evolution. The high incident of symmetry transitions poses the question concerning the homology of underlying developmental processes. I conducted a comprehensive study of developmental expression of symmetry across angiosperms covering 72 families and 39 orders. A wide range of timing for the expression of symmetry was found from organ initiation, to enlargement, to late differentiation of organs. In many studied genera, the symmetry pattern was transient during development. Mapping the floral symmetry patterns on the phylogenetic tree indicated the scattered distribution of patterns across angiosperms. The expression of symmetry was also versatile within families. The developmental constraints exerted by the inflorescence, bracts, neighbor flowers or neighbor organs within a flower could provide a possible explanation for the observed variation of symmetry expression.

Pollination of Cretaceous flowers

Insect pollination of flowering plants (angiosperms) is responsible for the majority of the world's flowering plant diversity and is key to the Cretaceous radiation of angiosperms. Although both insects and angiosperms were common by the mid-Cretaceous, direct fossil evidence of insect pollination is lacking. Direct evidence of Cretaceous insect pollination is associated with insect-gymnosperm pollination. Here, we report a specialized beetle-angiosperm pollination mode from mid-Cretaceous Burmese amber (99 mega-annum [Ma]) in which a tumbling flower beetle (Mordellidae), Angimordella burmitina gen. et sp. nov., has many tricolpate pollen grains attached. A. burmitina exhibits several specialized body structures for flower-visiting behavior including its body shape and pollen-feeding mouthparts revealed by X-ray microcomputed tomography (micro-CT). The tricolpate pollen in the amber belongs to the eudicots that comprise the majority of extant angiosperm species. These pollen grains exhibit zoophilous pollination attributes including their ornamentation, size, and clumping characteristics. Tricolpate pollen grains attached to the beetle's hairs are revealed by confocal laser scanning microscopy, which is a powerful tool for investigating pollen in amber. Our findings provide direct evidence of insect pollination of Cretaceous angiosperms, extending the range insect-angiosperm pollination association by at least 50 million years. Our results support the hypothesis that specialized insect pollination modes were present in eudicots 99 million years ago.

Wildflower plantings harbor increased arthropod richness and abundance within agricultural areas in Florida (USA)

AbstractIntensive agriculture has led to a reduction of overall biodiversity and ecosystem services such as pollination and biological control. To offset these economic losses, many farmers are planting native wildflowers to enhance flowering plant diversity and augment pollinator and other beneficial arthropod populations on their farms. In this study, we examined arthropod communities in Florida (USA) within wildflower plots and fallow control plots, which were primarily composed of grasses. Significantly more herbivorous insects, predatory arthropods, and pollinators were found within wildflower plots than in fallow control plots. We also implemented pollinator surveys at flowering plants. These surveys highlighted numerous plant–pollinator interactions within wildflower plots, supporting the idea that some native wildflower species are more attractive to pollinators than are others. Nevertheless, utilizing diverse flowering plants for wildflower plots may support a wide diversity of beneficial arthropod species, including native bees. Our results suggest that wildflower plantings in Florida can be a successful management tool to harbor increased overall plant and arthropod diversity (including native pollinators and other beneficial arthropods) within intensive agricultural areas.

Disentangling the diversity of definitions for the pollination ecosystem service and associated estimation methods

Observed declines in pollinator populations due to human pressures is of critical concern because pollination is an essential regulating ecosystem service (ES). Pollination has a major role in human food production and in maintaining flowering plant diversity. Estimating the pollination ES and its trends is thus essential for informing policy and management. However, the pollination ES remains poorly defined in practice as it is a polysemic term. In practice it is considered as: the ecosystem capacity to support pollination, the social demand for pollination or the actual pollination flow, which is the match between capacity and demand. Its quantification is complicated by the coexistence of numerous indicators. In this paper, we aimed to disentangle the diversity of definitions of the pollination service along with their associated indicators and field methods in the ecosystem service literature. From 131 reviewed papers, most studies were under temperate climate with a focus on hymenopteran pollinators, overlooking the importance of hoverflies and other dipteran pollinators. We identified four main pollination ES definitions that can be separated in two categories: (1) pollinator presence and pollen transfer, which are related to the capacity of the pollination ES; and (2) pollination success and production of fruits or seeds for human consumption, which are related to the flow of the pollination ES. Importantly, when quantified simultaneously pollination capacity and flow showed varying levels of congruence. Half of the reported relationships were congruent, but almost as many were neutral. Direct indicators of the two definitional categories characterised the respective actors of the pollination function. Studies of pollination capacity characterised pollinating agents (pollinator communities), while pollination flow studies described seeds and/or fruits produced from animal pollination. Both pollination capacity definitions share insect observations and captures as most frequent methods (70% of analysed studies), with a prevalence of indicators of pollinator diversity and abundance. Pollination flow estimation methods mainly describe the amount (number, weight) and quality of seeds/fruits. Pollinators depend on availability of feeding and nesting resources for their survival, and on their ability to reach them within landscapes. Thus, common indirect indicators of pollination are environmental variables related to semi-natural habitats and flower resources. We end this review with guidelines for relevant choices by ecosystem services scholars and practitioners of indicators and methods according to study questions and constraints (technical, financial, time and skills). Further investigations will be necessary to disentangle pollination capacity and flow relationships.

Urban development decreases bee abundance and diversity within coastal dune systems

Globally, coastal human population density is approximately three times than that of inland areas. Such development threatens the integrity of coastal ecosystems. Coastal dune systems contain unique sets of terrestrial invertebrates and native plants, and represent some of the last remaining areas of semi-natural habitats along the coasts. In our study, we monitored bee and flowering plant abundance and diversity within coastal dune systems located within protected lands and developed sites throughout South and Central Florida. Our aim was to assess the potential impacts dune degradation and development could have on these economically and ecologically important insects. A total of 5419 bees from 5 families and 56 taxa were captured using bowl traps. Halictidae accounted for 70% of all bees collected, followed by Apidae (28%), Megachilidae (2%), Andrenidae (0.1%) and Colletidae (0.07%). Both species richness and Shannon-Wiener diversity indices were higher in protected lands when compared with developed sites. A majority of the commonly collected bee species showed higher abundances in protected lands compared with developed sites. Protected lands also supported higher abundances of ground, wood, and tunnel-nesting bees when compared with developed sites. Bee species richness and Shannon-Wiener indices were lower in sites with greater percentages of development occurring within close proximity to the dune systems, and higher in sites with greater availability of dune coverage. We observed higher abundance and flowering plant species richness within protected lands when compared with developed sites; protected lands also supported more federally endangered/threatened or state protected plant species compared with developed sites. Overall, coastal dune systems are ecologically important bee sanctuaries and should be conserved to help sustain native bee communities and the flowering plants that occur within them.

Wildfires Influence Abundance, Diversity, and Intraspecific and Interspecific Trait Variation of Native Bees and Flowering Plants Across Burned and Unburned Landscapes

Wildfire regimes are changing in the western United States, yet we have little basic understanding of how wildfires influence native bees, the resources they depend on for food and nesting, or the traits that influence their interactions with plants. In burned and unburned areas in Montana, USA, we investigated the abundance and diversity of native bees, floral and nesting resources, nesting success, and traits of flowers and bees. In two of the three localities studied, burned areas, including areas that burned with high-severity wildfires, supported higher density and diversity of native bees and the flowers they depend on for food and larval provisioning. Burned areas also had more bare ground for ground-nesting bees and more available coarse woody debris for cavity-nesting bees than unburned areas. Moreover, cavity-nesting bees were completely unsuccessful at nesting in artificial nesting boxes in unburned areas, while nesting success was 40% in burned areas. Mean bee intertegular distance (a trait strongly correlated with tongue length, foraging distance, and body size) was similar between burned and unburned areas. However, wildfires influenced both interspecific and intraspecific trait variation of bees and plants. Intraspecific variation in bee intertegular distance was higher in unburned than burned areas. Both interspecific and intraspecific variation in floral traits important for interactions with pollinators were generally higher in burned than unburned areas. Thus, wildfires generally increased the density and species diversity of bees and flowers as well as trait variation at both trophic levels. We conclude that wildfires – even large, high-severity wildfires – create conditions that support native bees and the resources they need to flourish, but that unburned areas maintain trait variation in landscape mosaics with heterogeneous fire conditions.

Annual cover crops for managed and wild bees: Optimal plant mixtures depend on pollinator enhancement goals

Agricultural intensification and landscape simplification have reduced flowering plant abundance and diversity worldwide, with subsequent negative effects on pollinators. To mitigate these effects, research and conservation have focused on incorporating flowering plants into agricultural landscapes through on-farm natural areas or flowering crops. However, while cover crops provide numerous agroecosystem services, they have received little attention for their role in providing floral resources for pollinators. In this study, we examined the value of cover crops for providing supplemental summer floral resources for both managed and wild bees in the Northern Great Plains of the United States, where a large proportion of honey bee colonies spend the summer. Specifically, using an experimental randomized plot design, we compared floral resources and bee visitation rates across 1, 2, 3, and 6-species cover crop mixes as well a 6-species annual native wildflower mix. We found that cover crop treatments including buckwheat provided the highest summer-long floral cover, higher than the annual native wildflower mix in which only two of six species bloomed, and that total bee visitation rates increased with higher floral cover. However, different bees were attracted to different treatments; honey bees and bumble bees were most attracted to mixes containing phacelia, while large-bodied solitary bees were more attracted to mixes including cultivated sunflower and to the wildflower mix, illustrating that the optimal plantings for attracting social or managed bees may differ from those attracting solitary wild bees. Additionally, while similar numbers of bee species visited the three main plants in our treatments (buckwheat, phacelia, and cultivated sunflower) more rare species visited cultivated sunflower while more common bees visited buckwheat and phacelia. Our results highlight the value of annual cover crops for providing pollinator resources in agricultural landscapes, particularly on rotated land where perennial flower plantings are less feasible, but illustrate trade-offs between attracting a large number of common generalist or managed bees versus attracting fewer individuals but species of potential conservation concern.

A checklist of flowering plants of Panchase Protected Forest, Kaski district, central Nepal

Panchase Protected Forest (PPF), situated at the junction of three districts Kaski, Syangjaand Parbat with an elevation range of 900-2517m representing mid hills of Nepal. This study was carried out with an aim of documenting the flowering plant diversity of the Panchase Protected Forest, Kaski district, comprising three VDCs, Bhadaure Tamage, Chapakot and Pumdi Bhumdi. General survey, covering all seasons was organized (from June 2014 to May2015) for collecting the plant species. Published literatures and herbarium specimens were also consulted for documenting the species. Identification of the collected specimens was made through consulting relevant literatures, herbarium specimens and expert consultation. A total of 613 species belonging to 393 genera and 111 families have been documented from this area. The dominant family was Orchidaceae (49 genera and 125 species) followed by Poaceae (25 spp.), Asteraceae (25 spp.) and others. Six endemic plants, Begonia flagellaris (Begoniaceae), Eria pokharensis, Gastrochilus nepalensis, Oberonia nepalensis, Odontochilusnandae and Panisea panchaseensis (Orchidaceae) were also reported. Similarly, presentresearch revealed two taxa as new record for flora of Nepal, Dischidia bengalensis Colebr. (Apocynaceae) and Phreatia elegans Lindl. (Orchidaceae). The present findings suggest that PPF is one of the hotspot for floral diversity representing mid hills of Nepal and this pristine habitat for orchid should be developed as ‘Orchid Sanctuary’.

Key environmental determinants of global and regional richness and endemism patterns for a wild bee subfamily

Reports of world-wide decline of pollinators, and of bees in particular, raise increasing concerns about maintenance of pollination interactions. While local factors of bee decline are relatively well known and potential mitigation strategies at the landscape scale have been outlined, the regional and continental-scale threats to bee diversity have only been marginally explored. Here we document large-scale spatial patterns for a representative bee subfamily, the determinants of its species richness, and assess major threats to these pollinators. Using a comprehensive global dataset of Colletinae (genera Colletes, also called “polyester” or “cellophane” bees for their underground nests lined with a polyester secretion, and Mourecotelles), a species-rich subfamily whose organismal and physiological ecology is representative of many bees, we measured species richness and endemism on global to continental scales. We explored the relationships between bee species richness and potential environmental stress factors grouped into three categories: contemporary climate, habitat heterogeneity, and anthropogenic pressure. Bees of the subfamily Colletinae demonstrate the reversed latitudinal gradient in species richness and endemism suggested for bees; the highest species richness of Colletinae was found between 30° and 50° latitude in both the northern and southern hemispheres. Centres of endemism largely overlapped with those of species richness. The importance of the Greater Cape Floristic Region, previously identified as a centre of richness and endemism of bees, was confirmed for Colletinae. On the global scale, present-day climate was a significant predictor of species richness as was flowering plant diversity represented by vascular plant species richness and centres of plant diversity. Our main conclusion is that climate change constitutes a potential threat to bee diversity, as does declining diversity of vascular plants. However, a significant overlap between centres of bee richness and plant diversity might increase chances for developing conservation strategies.

Effects of landscape cover and local habitat characteristics on visiting bees in tropical orchards

Abstract Global population declines of insect pollinators highlight the need for a greater ecological understanding of the responses of wild pollinators to local management actions and to human alterations of landscapes, especially in the tropics where crops are highly dependent on wild pollinators. We examined the effects of local and landscape factors on the richness and abundance of bees in farms around Bangkok, Thailand. Bee communities in 24 mango (Mangifera indica L.) orchards in heavily modified landscapes (61–99% anthropogenic land cover) were compared. We predicted that bees would be more species rich in orchards with higher flower diversity, whereas small‐sized bees with non‐eusocial and/or below‐ground nesting habits would be more sensitive to human disturbance, and hence rare. Twenty‐eight species were caught and individuals of genus Apis comprised >92% of 3842 bees sampled and dominated all 24 sites. Habitat effects on bee richness and abundance were stronger at the farm scale than at the landscape scale. At the farm scale, total bee richness and abundance, as well as small, non‐eusocial and below‐ground nesting bee richness and abundance, were negatively associated with field size and positively associated with flowering plant diversity. The percentage of urban land cover within a 1‐km radius was weakly but positively related to total bee richness and small‐sized bee richness; total bee abundance was positively associated with wetland cover. A greater diversity of flowering plants retained in smaller fields maintained higher bee richness and abundances, particularly small‐sized bees. Farmers can enhance bee populations by maintaining small patches of flowers in their fields.

Bee communities along a prairie restoration chronosequence: similar abundance and diversity, distinct composition.

Recognition of the importance of bee conservation has grown in response to declines of managed honey bees and some wild bee species. Habitat loss has been implicated as a leading cause of declines, suggesting that ecological restoration is likely to play an increasing role in bee conservation efforts. In the midwestern United States, restoration of tallgrass prairie has traditionally targeted plant community objectives without explicit consideration for bees. However, restoration of prairie vegetation is likely to provide ancillary benefits to bees through increased foraging and nesting resources. We investigated community assembly of bees across a chronosequence of restored eastern tallgrass prairies and compared patterns to those in control and reference habitats (old fields and prairie remnants, respectively). We collected bees for 3yr and measured diversity and abundance of in-bloom flowering plants, vegetation structure, ground cover, and surrounding land use as predictors of bee abundance and bee taxonomic and functional diversity. We found that site-level variables, but not site type or restoration age, were significant predictors of bee abundance (bloom diversity, P=0.004; bare ground cover, P=0.02) and bee diversity (bloom diversity, P=0.01). There were significant correlations between overall composition of bee and blooming plant communities (Mantel test, P=0.002), and both plant and bee assemblages in restorations were intermediate between those of old fields and remnant prairies. Restorations exhibited high bee beta diversity, i.e., restored sites' bee assemblages were taxonomically and functionally differentiated from each other. This pattern was strong in younger restorations (<20yr old), but absent from older restorations (>20yr), suggesting restored prairie bee communities become more similar to one another and more similar to remnant prairie bee communities over time with the arrival of more species and functional groups of bees. Our results indicate that old fields, restorations, and remnants provide habitat for diverse and abundant bee communities, but continued restoration of old fields will help support and conserve bee communities more similar to reference bee communities characteristic of remnant prairies.

Evolution of floral diversity: genomics, genes and gamma.

A salient feature of flowering plant diversification is the emergence of a novel suite of floral features coinciding with the origin of the most species-rich lineage, Pentapetalae. Advances in phylogenetics, developmental genetics and genomics, including new analyses presented here, are helping to reconstruct the specific evolutionary steps involved in the evolution of this clade. The enormous floral diversity among Pentapetalae appears to be built on a highly conserved ground plan of five-parted (pentamerous) flowers with whorled phyllotaxis. By contrast, lability in the number and arrangement of component parts of the flower characterize the early-diverging eudicot lineages subtending Pentapetalae. The diversification of Pentapetalae also coincides closely with ancient hexaploidy, referred to as the gamma whole-genome triplication, for which the phylogenetic timing, mechanistic details and molecular evolutionary consequences are as yet not fully resolved. Transcription factors regulating floral development often persist in duplicate or triplicate in gamma-derived genomes, and both individual genes and whole transcriptional programmes exhibit a shift from broadly overlapping to tightly defined expression domains in Pentapetalae flowers. Investigations of these changes associated with the origin of Pentapetalae can lead to a more comprehensive understanding of what is arguably one of the most important evolutionary diversification events within terrestrial plants.This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'.

Diversity of Flowering Plants in Nubri Valley, Manaslu Conservation Area, Central Nepal

Central Nepal has long history in the field of botanical investigation in contrast with different parts of the nation. Nevertheless, the present study area (Manaslu Conservation Area) is still under-explored. The present floristic study was carried out with the aim of fulfilling this gap by giving particular attention on flowering plants and their documentation. Two field visits were directed in May-June 2012 and September-October 2012 in two unique seasons with a specific end goal to gather plant samples of both seasons. On the contrary, herbarium specimens were prepared and later identified at Tribhuvan University Central Herbarium (TUCH) and National Herbarium and Plant Laboratory (KATH). The present study uncovers the presence of 276 species of flowering plants belonging to 78 families and 200 genera of which 63 families belong to dicotyledons and 15 families belong to monocotyledons. Among these, 17 species (6.15%) of climbers, 178 species (64.49%) of herbs, 58 species (21.01%) of shrubs and 23 species (8.33%) of trees are found. Economically important flowering plants comprise about 156 species where 75 species are used as medicine, 29 species as fuel wood, 23 species as fodder, 29 species are edible, 6 species are for religious purpose, 5 specifically for construction purpose, 10 for ornamental and 13 species reported to have miscellaneous uses. MCA accounts to 9 flowering plant species for research and development and agro-technology development and 12 species are listed under IUCN and CAMP threatened categories. MCA and its affinity are likewise house to 10 endemic flowering plants. As from the study it can be inferred that Manaslu Conservation Area (MCA) is a treasure hub of flowering plants that not only represent its economic importance rather it is also a house to threaten and endemic flowering plants. Thus, proper management plans must be implemented for the conservation of resources in MCA.

Virion Structure of Israeli Acute Bee Paralysis Virus.

ABSTRACTThe pollination services provided by the western honeybee (Apis mellifera) are critical for agricultural production and the diversity of wild flowering plants. However, honeybees suffer from environmental pollution, habitat loss, and pathogens, including viruses that can cause fatal diseases. Israeli acute bee paralysis virus (IAPV), from the family Dicistroviridae, has been shown to cause colony collapse disorder in the United States. Here, we present the IAPV virion structure determined to a resolution of 4.0 Å and the structure of a pentamer of capsid protein protomers at a resolution of 2.7 Å. IAPV has major capsid proteins VP1 and VP3 with noncanonical jellyroll β-barrel folds composed of only seven instead of eight β-strands, as is the rule for proteins of other viruses with the same fold. The maturation of dicistroviruses is connected to the cleavage of precursor capsid protein VP0 into subunits VP3 and VP4. We show that a putative catalytic site formed by the residues Asp-Asp-Phe of VP1 is optimally positioned to perform the cleavage. Furthermore, unlike many picornaviruses, IAPV does not contain a hydrophobic pocket in capsid protein VP1 that could be targeted by capsid-binding antiviral compounds.IMPORTANCE Honeybee pollination is required for agricultural production and to sustain the biodiversity of wild flora. However, honeybee populations in Europe and North America are under pressure from pathogens, including viruses that cause colony losses. Viruses from the family Dicistroviridae can cause honeybee infections that are lethal, not only to individual honeybees, but to whole colonies. Here, we present the virion structure of an Aparavirus, Israeli acute bee paralysis virus (IAPV), a member of a complex of closely related viruses that are distributed worldwide. IAPV exhibits unique structural features not observed in other picorna-like viruses. Capsid protein VP1 of IAPV does not contain a hydrophobic pocket, implying that capsid-binding antiviral compounds that can prevent the replication of vertebrate picornaviruses may be ineffective against honeybee virus infections.

Habitat type plays a greater role than livestock grazing in structuring shrubsteppe plant–pollinator communities

Livestock grazing is a widespread grassland disturbance and can negatively impact biodiversity. Pollinators constitute a vital component of grassland ecosystems, but the impact of grazing on pollinator diversity has seldom been evaluated in North America. We assessed vegetation structure, and pollinator and flowering plant abundance, richness, diversity, and community composition in four pairs of spring-grazed/ungrazed sites in south-central British Columbia, Canada. We also investigated whether pollinator or floral communities differed between the two threatened shrubsteppe habitat types we sampled—antelope-brush and big sagebrush shrubsteppe. Pan-trapping surveys captured 5907 bees, flies, beetles, wasps and butterflies constituting 253 species. We found that the percent cover of shrubs and bare soil increased with grazing, while the height of grasses and forbs decreased. In contrast, pollinator and flowering plant abundance, richness, diversity, and community composition were not significantly affected by grazing. Flowering plant and pollinator community composition did differ significantly between shrubsteppe habitats. Our results indicate that grasslands in North America, when managed responsibly, can maintain pollinator and flowering plant diversity under grazing pressure. The continued effort of land managers to balance ecological integrity and economic viability will be important for the conservation of grassland pollination systems.

Early evolution of the angiosperm clade Asteraceae in the Cretaceous of Antarctica

The Asteraceae (sunflowers and daisies) are the most diverse family of flowering plants. Despite their prominent role in extant terrestrial ecosystems, the early evolutionary history of this family remains poorly understood. Here we report the discovery of a number of fossil pollen grains preserved in dinosaur-bearing deposits from the Late Cretaceous of Antarctica that drastically pushes back the timing of assumed origin of the family. Reliably dated to ∼76-66 Mya, these specimens are about 20 million years older than previously known records for the Asteraceae. Using a phylogenetic approach, we interpreted these fossil specimens as members of an extinct early diverging clade of the family, associated with subfamily Barnadesioideae. Based on a molecular phylogenetic tree calibrated using fossils, including the ones reported here, we estimated that the most recent common ancestor of the family lived at least 80 Mya in Gondwana, well before the thermal and biogeographical isolation of Antarctica. Most of the early diverging lineages of the family originated in a narrow time interval after the K/P boundary, 60-50 Mya, coinciding with a pronounced climatic warming during the Late Paleocene and Early Eocene, and the scene of a dramatic rise in flowering plant diversity. Our age estimates reduce earlier discrepancies between the age of the fossil record and previous molecular estimates for the origin of the family, bearing important implications in the evolution of flowering plants in general.

Back to the past: a new take on the timing of flowering plant diversification.

Back to the past: a new take on the timing of flowering plant diversification.

Effect of Biotic and Abiotic Factors on Diversity Patterns of Anthophyllous Insect Communities in a Tropical Mountain Forest

The determinants of diversity are a central issue in ecology, particularly in Andean forests that are known to be a major diversity hotspot for several taxa. We examined the effect of abiotic (elevation and precipitation) and biotic (flowering plant diversity) factors considered to be decisive causal factors of diversity patterns on anthophyllous insect communities on mountain forest. Sampling was carried out in 100-m transects at eight elevational levels and during a period of 8 months. All flowering plants in the understory and their flowering visitors were recorded. Species richness and diversity were estimated for each elevation and month. Diversity of flowering plants, elevation, and precipitation were used as independent variables in multiple regressions against insect diversity. The evaluated abiotic and biotic factors had contrasting effects on insect diversity: a significant decrease on insect diversity occurred at high elevation and dry months (i.e., threshold effect), while it showed a positive relationship with flowering plant diversity through time (i.e., linear effect), but not along elevation. Rapid turnover of species of both interacting guilds was observed every 100-m altitude and month. Local insect communities were also divided functionally depending on the plant family they visit. These results indicate that each insect community is distinctive among elevations and months and that diversity of flowering plants, precipitation, and elevation influence their structure and composition. Thus, conservation strategies should involve protection of forest cover at the whole elevation gradient, in order to preserve common and exclusive components of diversity and consequently, the mosaic of plant-pollinator interactions.

Pollen (microgametophyte) competition: an assessment of its significance in the evolution of flowering plant diversity, with particular reference to seed germination

A hypothesis by David L. Mulcahy published in Science in 1979 on pollen competition as an important force in the evolution of flowering plant diversity, via selection of favourable genes in the microgametophyte that are passed on to, and inherited in, the sporophyte, stimulated quite a bit of research on the topic. The primary aim of this opinion paper is to assess the evidence for the effect of microgametophyte competition on the sporophyte, with particular reference to seed germination. Pollen competition was associated with an increase in seed germination in 14 of 30 case studies (30 published papers). Seed mass was related to better germination in only two of the 14 cases in which there was a positive effect of pollen competition on germination. An evaluation of the four criteria that must be met to validate Mulcahy's hypothesis cast some doubt on the significance of pollen competition as an important selective force in the diversification of angiosperms. Insect pollination, via which many pollen grains are deposited on a stigma, may not be the answer to Darwin's ‘abominable mystery’ concerning the reason for the abrupt origin and rapid diversification of flowering plants during the Cretaceous.