Mating by outcrossing plants depends on the frequency and quality of interaction between pollen vectors and individual flowers. However, the historical focus of pollination biology on individual flowers (floricentrism) cannot produce a complete understanding of the role of pollination in plant mating, because mating is an aggregate process, which depends on the reproductive outcomes of all of a plant’s flowers. Simultaneous display of multiple flowers in an inflorescence increases a plant’s attractiveness to pollinators, which should generally enhance mating opportunities.
Clonality is very common in flowering plants, but its consequences for sexual reproduction have rarely been explored. While clonal growth can increase the number of flowers a plant produces it may also limit reproductive success through pollen discounting (reduction in pollen exported to adjacent clones) and pollen limitation (failure of outside pollen to reach the centre of a clone). Using clones of domestic apple (Malus x domestica) that ranged from 1 to 5 orchard rows wide, we found that the patterns of siring success were consistent with the presence of pollen discounting, but we failed to detect evidence for pollen limitation.
Dichogamy, the temporal separation of gender within a flower, is widespread throughout the angiosperms, occurring in over 250 families. There are two forms of dichogamy: protandry, in which male function precedes female function, and protogyny, the converse. Dichogamy has traditionally been interpreted as a mechanism to avoid inbreeding. However, recent evidence indicates that this inbreeding-avoidance hypothesis cannot completely explain the evolution of dichogamy. An alternate hypothesis is that dichogamy acts to reduce interference between gender functions.
The outcrossing rate is a fundamental attribute of plant populations that determines population genetic structure, individual plant fitness, and ultimately speciation rates. The outcrossing rate can be influenced by population size through reductions in both mate availability and pollinator service. We investigated the effect of population size on the outcrossing rate in 10 populations of Aquilegia canadensis in Southern Ontario, Canada.
Across a range of sizes from 32 to 750 reproductive individuals, we found that small populations (n 90, blue line).
As I use R for data analysis and simulations, I become more comfortable and proficient with the R/S syntax and style of programming. One important insight is the use of vector assignments in simulations. I have often read that using such assignments is the preferred method, but until recently I had not realised the importance of this statement. To illustrate the use of vector assignments and their advantages, consider two models of the style illustrated below:
A particular challenge with maintaining a weblog is the uploading and resizing of images. The process involves choosing the correct images, creating large & thumbnail sized versions, uploading these images to the webserver, and posting the appropriate code into the weblog post. In the spirit of my last few posts, image2web is an applescript I use to automate this process:
--user-specific variables property theAlbum : "Marked" --contains the images to be uploaded property theBasePath : "
The CBC has begun an experiment with podcasting. I’m impressed with the progressive approach to technology that the CBC has adopted and hope they expand the experiment to more of their programs.
This has the added effect of making my Quirks & Quarks download script obsolete.
Quirks & Quarks is the CBC’s excellent science program. I usually download the mp3 archives of the show on the weekends and listen while I walk Ceiligh.
Of course, loading up the Quirks & Quarks webpage, finding the archives, downloading the mp3s, and adding them to iTunes takes at least a few minutes. Computers are much better and handling such tedium.
Inspired by the success (for me) of the apod script, quirks.
The “Astronomy Picture of the Day” is a source of fantastic images. To take advantage of this resource, I went looking for a way to automatically set the current image as my Desktop background. A quick Google search turned up a perl script at www.haroldbakker.com. Although this was a great start, I wasn’t completely happy with the implementation of this script and decided to write my own.
The apod.pl script is written in perl and both sets the Desktop background and copies a description of the image to the Desktop as an html file.
These data measured the genetic architecture of male-phase duration in Chamerion angustifolium. There are three files in the archive used to estimate genetic variances & covariances with VCE. Format:
protandryHeritabilityData.dat: Contains the measured data for male- & female-phase duration, flower size, & display size protandryHeritabilityPedigree.ped: Contains the pedigree information for the selection experiment protandryHeritabilityVCE: Is the VCE file that configures the analysis Citation:
Routley, M.B. & B.C. Husband. 2004. Responses to selection on male-phase duration in Chamerion angustifolium.
A recent column in the Globe & Mail reminded me of our Federal Government’s plan for reducing greenhouse gas emissions: the One Tonne Challenge.
This campaign challenges each Canadian to reduce their contribution to greenhouse gas emissions by one tonne. The first step is to calculate your emissions and then implement recommendations for reductions. According to the online calculator, Kelly & I combined emit 4.23 tonnes annually. Fortunately, this is below the national average of 5.
Yet another useful site from Google: Google Scholar. The site provides an interface for searching the scientific literature with typical Google ease. Some preliminary tests suggest that it is quite effective at finding relevant literature.
I’ve written a script that imports a JSTOR citation page into BibDesk. To use the script, I suggest adding it to your script menu. Then, with the JSTOR citation page as the active web page in Safari, run the script and the citation will be added to the active BibDesk file. I use the first author’s last name and last two digits of the year as a cite key (e.g. Darwin59), you may want to change this to suit your style.
An interesting read from Wired News – The Crusade Against Evolution. In addition, the Panda’s thumb has been following and carefully dissecting the recent controversy over an intelligent design paper being published in a peer-reviewed journal. The evolution-creation debate seems to be resurfacing after a short time off. The debate is important and the intelligent design supporters have to be countered, but their arguments have become hackneyed.
Plants are sessile and, consequently, many species rely on pollinators for mating opportunities. However, pollinators do not necessarily visit every individual in a population with equal frequency. Plant attributes, such as floral display and reward provisioning, can influence the frequency of pollinator visitation. Furthermore, aspects of population density and structure may also influence visitation patterns. One effect of this unequal distribution of pollinator activity is that pollinators create networks of connections between plants in which a few plant receive many visits and many plants receive few visits.
There’s a powerful approach to modelling called dynamic state variable programming, covered in Dynamic State Variable Models In Ecology by Clark & Mangel. I’ll post more about the approach sometime, but for now I wanted to make an example from the book available. The first chapter of the book includes a guide through the creation of a patch foraging model. A fully implemented version is available in True BASIC, but I’ve decided to use R for all of my modelling and analyses.
Until recently, I was able to use journal abbreviations in all of my manuscripts. Consequently, my .bib file contains only abbreviations in the journal field. Now I need to produce some bibliographies with full journal names. With a .bib file you can use macros to handle changing abbreviated names to full names. However, BibDesk cannot use macros. Instead I wrote a perl script that searches through a .bib file and creates a new file with journal abbreviations changed to full names.
I have been investigating issues of ovule and seed development recently. One question that has come up is: How much variation is there in seed size? I had analysed some seed set data for some earlier work with some image analysis software. Consequently I have a large data set of seed area and perimeter for Chamerion angustifolium. A rough look at the data is:
The data set is available as seedSizeData.