Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

An essential textbook for any student or researcher in biology needing to design experiments, sample programs or analyse the resulting data The text begins with a revision of estimation and hypothesis testing methods, covering both classical and Bayesian philosophies, before advancing to the analysis of linear and generalized linear models Topics covered include linear and logistic regression, simple and complex ANOVA models (for factorial, nested, block, split-plot and repeated measures and covariance designs), and log-linear models Multivariate techniques, including classification and ordination, are then introduced Special emphasis is placed on checking assumptions, exploratory data analysis and presentation of results The main analyses are illustrated with many examples from published papers and there is an extensive reference list to both the statistical and biological literature The book is supported by a website that provides all data sets, questions for each chapter and links to software

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Experimental Design and Data Analysis for Biologists

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.

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Importance of pollinators in changing landscapes for world crops

Evolution of Protein Molecules

Part I: Introduction1. Species Interactions and the Evolution of Biodiversity. (Peter W. Price)2. The History of Associations between Plants and Animals. (Conrad C. Labandeira)Part II: Mostly Antagonisms3. Plant-Insect Interactions in Terrestrial Ecosystems. (Sharon Y. Strauss and Arthur R. Zangerl)4. Mammalian Herbivory in Terrestrial Environments. (Kjell Danell and Roger Bergstrom)5. Granivory. (Philip E. Hulme and Craig W. Benkman)Part III: Mostly Mutualisms6. Pollination by Animals. (Olle Pellmyr)7. Seed Dispersal by Vertebrates. (Carlos M. Herrera)Part IV: Synthesis8. Ant-Plant Interactions. (Andrew J. Beattie and Lesley Hughes)9. Plant-Animal Interactions: Future Directions. (John N. Thompson)Appendix: Supplementary Information for Chapter 2

Plant-animal interactions : an evolutionary approach

The recruitment of Phillyrea latifolia L. (Oleaceae), a bird-dispersed tree of Mediterranean forest, is described. Fruit removal by birds, seed rain, post-dispersal seed predation, seed germination, and seedling emergence, survival, and establishment were studied. The main objective was testing whether seed dispersal by birds produced a pre- dictable seedling shadow as a result of coupled patterns of seed rain, seedling emergence, and seedling establishment. P. latifolia is a mast-fruiting species and large fruit crops were produced in only 2 (1981 and 1989) out of 15 yr (1978-1992). We report here on the 1989 fruiting event at one scrubland and one forest site. Ripe fruits were available from mid-September to early June. Extensive removal by birds started after fruit crops of other species were depleted. Seed dispersers were more abundant, and fruit predators more scarce, in scrubland than in forest. P. latifolia fruits were a major component in the diet of principal seed dispersers (Sylvia atricapilla and Erithacus rubecula) that depended almost exclusively on them for food late in the season. Fruit removal levels were higher, crops were depleted earlier, and individual plants dis- persed more seeds in scrubland than in forest. Crop size was the best predictor of number of seeds dispersed by individual plants in scrubland, while fruit characteristics were more influential in forest. Seed dispersal was largely a within-population phenomenon, as no seed fall occurred in traps set beyond the distributional limits of P. latifolia in the study region. Frugivores produced a spatially predictable seed rain at the two sites. Seed rain was greatest beneath fleshy fruit-producing species (under female individuals in dioecious species) in scrubland and at forest-gap interfaces in forest. Post-dispersal seed predation was low at the two sites (39 and 54% after 1-yr exposure). In forest, seed survival was lower in gaps than in forest interior or forest edges. In scrubland, seed survival differed widely among microhabitats (defined by overlying plant species), ranging from 19% (open ground) to 61% (beneath Rosmarinus officinalis). In forest, density of emerging seedlings was unrelated to location in the habitat mosaic (gap, forest edge, interior). Seedling density did differ among microhabitats in scrubland, where emergence was greatest under fleshy fruit-producing species. Seedling survival was higher in forest than in scrubland, where seedlings incurred greater mortality due to desiccation. In both sites, seedling survival depended significantly on microhabitat and was depressed under adult conspecifics. The activity of frugivores directly impacted seedling distribution in scrubland, as spatial patterns of seed deposition were not overshadowed by later-acting factors, such as rodent seed predation or variation in germination. In forest, there was spatial discordance between seed rain and seedling distribution, as a consequence of uncoupled seed rain and seedling emergence. Spatial patterns of seed deposition by birds may thus have a lasting impact on the population dynamics of P. latifolia, but this will vary among populations depending on the extent of coupling of the different stages in the recruitment process (dispersal-seed rain-germination and seedling establishment).

/pdf/recruitment-of-a-mast-fruiting-bird-dispersed-tree-bridging-2rzm070iiw.pdf

Recruitment of a Mast‐Fruiting, Bird‐Dispersed Tree: Bridging Frugivore Activity and Seedling Establishment

A total of 34 floral visitors of Lavandula latifolia (Labiatae) at a southern Spanish locality were examined from the perspective of their "quality" as pollinators. I considered frequency of pollen transfer, number of pollen grains deposited on the stigma, selection of floral sexual stage (flowers are markedly protandrous), and patterns of flight distance between flowers. Hymenoptera deposited more pollen and more often than Lepidoptera or Diptera. The latter two groups did not differ in this respect. Interspecific variation in frequency of pollen delivery depended on differences in proportional visitation to female-stage (receptive) flowers as well as total pollen delivery to these flowers. Lepidoptera tended to fly longer distances between consecutive flowers than Hymenoptera. Hand-pollination experiments demonstrate that variation among floral visitors in reproductive services rendered may translate into differential fitness of L. latifolia plants. Nevertheless, the potential for plant specialization on specific insects is constrained by counterbalancing variation in components of pollination quality.

http://ebd06.ebd.csic.es/pdfs/Herrera.1987.Oikos.pdf

Components of pollinator "quality": comparative analysis of a diverse insect assemblage

Fruit production and patterns of seed dispersal by birds were studied at two elevations in the Mediterranean scrublands of southern Spain. Fleshy-fruit-producing species represent a very prominent fraction of woody plants in terms of cover (57-76%) and species number (49-66%). Fruit production occurs year round in the lowland site but is confined to August-February upslope. Ripe fruits are most abundant (>105 ripe fruits/ha) in November-December. Fruit abundance fluctuates widely between years at the highland locality but only slightly in the lowlands. In both communities, the dominant species ripen fruits in autumn-winter, display the highest within-plant fruit densities, and tend to have the most lipid-rich fruits. Fruits differ in pulp nutritive value, seediness, and relative amount of pulp among species but are remarkably uniform in size (mostly 5-10 mm transverse di- ameter). Two-thirds of the passerine species at each site eat some fruit. Of these species, 69% (highland) and 26% (lowland) are resident "fruit predators," feeding on either pulp or seeds alone, and damaging the seeds when eating pulp and seeds together. The rest are overwintering or migratory seed dispersers that ingest whole fruits without damaging seeds. Seed dispersers are most common in late autumn- winter, coincident with the peak in fruit abundance and the predominance of lipid-rich fruits. A few small (12-18 g body mass) disperser species (Erithacus rubecula, Sylvia atricapilla, Sylvia melano- cephala) account for most of the frugivory at each site and disperse the majority of seeds. Fruit predators either are relatively scarce or eat fruits infrequently, or fruits represent a negligible fraction of their diets. Fruit removal was very high (89-100% of crops) among species with fruits smaller than the gape width of the abundant small-sized dispersers, and very low among species with fruits larger than gape width. Removal success was negatively correlated with fruit size among species having fruits smaller than dominant dispersers' gape width. No relation has been found between removal success and fruit quality, fruiting time, ripening rate, or within-plant fruit density. The principal dispersers at each site ate mainly the most nutritious fruits, although not to the exclusion of less nutritious fruits. Substantial pairwise plant-bird reciprocity is not common. (The avian species disperses a substantial fraction of a plant's seeds, which in turn provide the bulk of the bird's energy supply.) Current bird-plant seed dispersal interactions are the result of evolutionary, climatic, and geo- graphical factors in the Mediterranean. Mutualistic congruency largely is, in these cases, an epiphe- nomenon of these factors, not resulting necessarily from mutual adaptations (coevolution). It is sug- gested that actual coevolution involving a smaller set of bird and plant species may facilitate the persistence of noncoevolving (or very slowly coevolving) plant species, thus favoring the existence of a chronic "anachronism load" (with regard to dispersal) in the plant community.

A Study of Avian Frugivores, Bird-Dispersed Plants, and Their Interaction in Mediterranean Scrublands

Variation in time (annual and seasonal) and space (between- and within-population) is examined for the pollinator assemblage of Lavandula latifolia (Labiatae), an insect-pollinated, summerflowering, evergreen shrub of Mediterranean woodlands in southeastern Spain. Lauandula latiflia is pollinated there by nearly 85 species of comparatively long-tongued Hymenoptera, Diptera and Lepidoptera. The diversity, composition and abundance of pollinators varied markedly between years. Lepidopteran taxa prevailed numerically in one year, hymenopterans in four years, and both groups had similar abundance in the remaining year. The vast majority of pollinators exhibited significant annual differences in average abundance. Only 35.7% of taxa were recorded in all of the six study years. The pollinator assemblage had marked seasonal dynamics. Important changes in species richness, abundance and composition took place over the flowering season of L. latiflia (nearly 3 months). Only 21.7y0 of insect taxa occurred throughout the flowering season. Lavandula latiflia populations at different distances from water courses differed broadly in the abundance and composition of pollinators. Hymenopterans dominated numerically at the water-distant sites, whereas lepidopterans prevailed in populations growing in the vicinity of streams. Only 40.7% of taxa were recorded at all of the four study populations. Within the same plant population, horizontal distances of the order of 25 m resulted in significant changes in pollinator composition. Variations at the four scales considered combine to produce, from the viewpoint of L. latifolia, a spatio-temporal mosaic of pollinators. As these differ broadly in frequency of pollen transfer, size of pollen loads deposited, and between-flower flight distance patterns, spatio-temporal variation will predictably result in inconsistent or contradictory selective pressures on the plant, thus hindering specialization in relation to particular pollinators.

http://ebd06.ebd.csic.es/pdfs/Herrera.1988.Biol.J.Linn.Soc.pdf

Carlos M. Herrera

Papers

Plant-animal interactions : an evolutionary approach

Recruitment of a Mast‐Fruiting, Bird‐Dispersed Tree: Bridging Frugivore Activity and Seedling Establishment

Components of pollinator "quality": comparative analysis of a diverse insect assemblage

A Study of Avian Frugivores, Bird-Dispersed Plants, and Their Interaction in Mediterranean Scrublands

Variation in mutualisms : the spatio temporal mosaic of a pollinator assemblage