Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

The extent of our reliance on animal pollination for world crop production for human food has not previously been evaluated and the previous estimates for countries or continents have seldom used primary data. In this review, we expand the previous estimates using novel primary data from 200 countries and found that fruit, vegetable or seed production from 87 of the leading global food crops is dependent upon animal pollination, while 28 crops do not rely upon animal pollination. However, global production volumes give a contrasting perspective, since 60% of global production comes from crops that do not depend on animal pollination, 35% from crops that depend on pollinators, and 5% are unevaluated. Using all crops traded on the world market and setting aside crops that are solely passively self-pollinated, wind-pollinated or parthenocarpic, we then evaluated the level of dependence on animal-mediated pollination for crops that are directly consumed by humans. We found that pollinators are essential for 13 crops, production is highly pollinator dependent for 30, moderately for 27, slightly for 21, unimportant for 7, and is of unknown significance for the remaining 9. We further evaluated whether local and landscape-wide management for natural pollination services could help to sustain crop diversity and production. Case studies for nine crops on four continents revealed that agricultural intensification jeopardizes wild bee communities and their stabilizing effect on pollination services at the landscape scale.

/pdf/importance-of-pollinators-in-changing-landscapes-for-world-2j8o9ygr29.pdf

Importance of pollinators in changing landscapes for world crops

Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare.

/pdf/global-pollinator-declines-trends-impacts-and-drivers-5gfi4zur4k.pdf

Global pollinator declines: trends, impacts and drivers.

Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple, interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future.

https://science.sciencemag.org/content/sci/early/2015/02/25/science.1255957.full.pdf

Bee declines driven by combined stress from parasites, pesticides, and lack of flowers

It is clear that the majority of fl owering plants are pollinated by insects and other animals, with a minority utilising abiotic pollen vectors, mainly wind. However there is no accurate published calculation of the proportion of the ca 352 000 species of angiosperms that interact with pollinators. Widely cited fi gures range from 67% to 96% but these have not been based on fi rm data. We estimated the number and proportion of fl owering plants that are pollinated by animals using published and unpublished community-level surveys of plant pollination systems that recorded whether each species present was pollinated by animals or wind. Th e proportion of animal-pollinated species rises from a mean of 78% in temperate-zone communities to 94% in tropical communities. By correcting for the latitudinal diversity trend in fl owering plants, we estimate the global number and proportion of animal pollinated angiosperms as 308 006, which is 87.5% of the estimated species-level diversity of fl owering plants. Given current concerns about the decline in pollinators and the possible resulting impacts on both natural communities and agricultural crops, such estimates are vital to both ecologists and policy makers. Further research is required to assess in detail the absolute dependency of these plants on their pollinators, and how this varies with latitude and community type, but there is no doubt that plant – pollinator interactions play a signifi cant role in maintaining the functional integrity of most terrestrial ecosystems. Plant – pollinator relationships may be one of the most ecologically important classes of animal – plant interaction: without pollinators, many plants could not set seed and reproduce; and without plants to provide pollen, nectar and other rewards, many animal populations would decline, with consequent knock-on eff ects for other species (Kearns et al.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0706.2010.18644.x

How many flowering plants are pollinated by animals

. Seed-feeding beetles of the genera Acanthoscelides, Apion, and occasionally Tychius were commonly found occurring in seeds from wild populations of Astragalus filipes and Dalea ornata across rangelands of the United States Intermountain West, resulting in many new state, county, and host records. These 2 legumes, as well as other perennial herbaceous species, are being commercially farmed to produce seed supplies to rehabilitate sagebrush-steppe and adjoining juniper woodlands following wildfires. Most of the seeds examined in this study hosted one or more seed-feeding beetles; beetles that pupate and overwinter in the seeds pose the risk of being transported to storage warehouses and distributed to new seedings, unless the beetles are first detected and then controlled.

/pdf/seed-feeding-beetles-bruchinae-curculionidae-brentidae-from-ym08ss5rhg.pdf

Seed-Feeding Beetles (Bruchinae, Curculionidae, Brentidae) from Legumes (Dalea ornata, astragalus filipes) and Other Forbs Needed for Restoring Rangelands of the Intermountain West

of the 4,000+ named species of wild bees that are native to North America. Except for bumblebees and some sweat bees, our native bees are solitary, not social, many with just one annual generation that coincides with bloom by their favorite floral hosts. In contrast, the familiar honeybee is highly social, has perennial colonies, and was brought to North America by settlers from Europe. Regardless of these differences, however, all of our bees need pollen and nectar from flowers. The sugars in sweet nectar power their flight; mother bees also imbibe some nectar to mix with pollen that they gather. Pollen is fortified with proteins, oils and minerals that are essential for the diets of their grub-like larvae back at the nest.

/pdf/gardening-for-native-bees-in-utah-and-beyond-2nq7iqlylk.pdf

Gardening for Native Bees in Utah and Beyond

Individuals of Glenostictia satan Gillaspy emerged from a small, sparsely vegetated area in Upper Sonoran desert. Males were considerably more numerous at the site than females and as many as 3000 males patrolled within this area at peak emergence. Males were site-constant, returning daily to restricted ranges within the total emergence area. These ranges were not defended against other males, and no male/male aggression was observed during periods of flying or walking. Numerous males clustered at digging sites, and upon discovering a female, attempted to mount her as she emerged from the ground. Males apparently were damaged in such clusters. One male would invariably succeed in mounting the female. The mounted pair walked away from the cluster, and other males in the cluster eventually dispersed. Dense concentrations of patrolling males are known to occur in some species of aculeate Hymenoptera. Among closely related species of Bembicini (Steniolia, Stictiella, and Gle nostictia), G. scitula forms dense nesting aggregations, and while the mating system is not fully known, it may resemble that of G. satan. In some less closely related aculeates (e.g., bees and other Sphecidae) where large nesting aggregations occur, similar mating systems have convergently evolved. G. satan is unusual in that pairs walk in copula, rather than fly, away from mating "balls". The site-constancy of males within the aggregation is known from some other species and may be more widespread than previously thought. The degree of aggregation of nests is a prominent factor which influences male mating strategies in aculeate Hymenoptera, in that it affects distribution of re ceptive females. If females emerge over an extended period of time within a restricted area, males can potentially mate with numerous females. Males may enhance their reproductive success by defending portions of the emergence area, or where higher nest densities are present, by patrolling emergence areas (Alcock

Male competition and mating behavior within mating aggregations of Glenostictia satan Gillaspy (Hymenoptera: Sphecidae)

Animal pollination depends on foragers moving pollen between conspecific flowers and plants. Pollinating bees often exhibit patch fidelity and frequent grooming during a foraging trip, which results in intensely localized pollen carryover. If their host’s seed dispersal is likewise limited, then spatial mosaics of small genetic neighbourhoods should result. However, spatial distributions of genetic markers of seeds often reveal infrequent long-distance gene flow mediated by pollinating bees, seemingly at odds with expectations of bees’ local patch fidelity and suggesting an additional mechanism at work. A greenhouse experiment that used nesting Osmia californica bees foraging at sunflowers tested the pollination fate of any bodily pollen that lingers on females even after they discharge a pollen load at their nest. Once a provisioning female had returned to her nest, we moved the nest with her inside from a cage with male-fertile sunflowers to a cage with male-sterile sunflowers. There females quickly resumed foraging. They nearly always pollinated and set seed at the first male-sterile flowerhead that they visited, the result of fertile bodily pollen carried over from the previous foraging trip. Every visit to a second male-sterile flowerhead set additional seed. If, as seems likely, outbound nesting females sometimes switch between host patches, then this mechanism of pollen carryover could explain occasional distant pollen-mediated gene flow events, as summarizes in a graphic model. Carryover should mitigate inbreeding depression in threatened plant populations, or conversely, sometimes contaminate seed crops, with relevance for spatially isolating foundation seed fields and coexistence of GMO and conventional crops.

/pdf/pollen-carryover-between-sequential-foraging-trips-by-a-2cuj62mn8v.pdf

Pollen carryover between sequential foraging trips by a solitary bee: Implications for distant outcrossing

\n Many plants produce broadly active toxins to which specialist herbivores—typically insects—have evolved counter-adaptations, sometimes spawning co-evolutionary arms races. Many non-social bee species are likewise taxonomic host specialists, but the specialists’ pollen hosts frequently attract diverse floral generalists as well, even to flowers of plants that are otherwise chemically defended. In this study of foothills death-camas, Toxicoscordion paniculatum (Nutt.) Rydberg (formerly Zigadenus), we show that its pollen and nectar both contain zygacine, the steroidal alkaloid responsible for this plant’s notorious mammalian toxicity. Hungry naïve adults of a generalist solitary bee, Osmia lignaria Say (Megachilidae), would briefly drink death-camas nectar or biologically relevant doses of zygacine in syrup, followed by prolonged bouts of irritable tongue grooming; many became paralyzed and some even died. Larvae fed dosed provision masses likewise often ceased feeding and sometimes died. Prolonged irritation and subsequent deterrence of foraging O. lignaria likely illustrates why it and 50+ other vernal bee species were absent from death-camas flowers in a five-state survey. The sole visiting bee, Andrena astragali, foraged exclusively at death-camas flowers for pollen and nectar. Thus, a toxic alkaloid found in death-camas pollen and nectar deters generalist bees from flowers of this pollinator-dependent monocot, restricting visitation to a single specialist bee that tolerates death-camas toxins and is its likely pollinator.

James H. Cane

Papers

Seed-Feeding Beetles (Bruchinae, Curculionidae, Brentidae) from Legumes (Dalea ornata, astragalus filipes) and Other Forbs Needed for Restoring Rangelands of the Intermountain West

Gardening for Native Bees in Utah and Beyond

Male competition and mating behavior within mating aggregations of Glenostictia satan Gillaspy (Hymenoptera: Sphecidae)

Pollen carryover between sequential foraging trips by a solitary bee: Implications for distant outcrossing

Neurotoxic alkaloid in pollen and nectar excludes generalist bees from foraging at death-camas, Toxicoscordion paniculatum (Melanthiaceae)