Using Molecular Power to Reconstruct Hyperdiverse Food Webs

Post provided by JORDAN CASEY

Coral Reefs: The Ocean’s Most Extravagant Buffet

Coral reefs are home to an incredibly diverse array of species ©Jordan Casey

Coral reefs are home to an incredibly diverse array of species ©Jordan Casey

There are an estimated 830,000 species on coral reefs worldwide. At some stage in their lives, nearly all of these species are consumed as prey items. In this super diverse buffet of fishes, corals, crabs, worms, and other critters, the number of possible interactions between predators and prey is nearly inexhaustible.

The extreme diversity of coral reefs has fascinated naturalists for centuries. Pinpointing predator-prey dynamics is essential to fully understand coral reef ecosystem dynamics, and visual analysis of gut contents has been a staple technique of coral reef ecologists. While the joy of spending copious hours looking through a microscope at half-digested marine mush is undeniable, this type of visual inspection has limitations. Even so, visual gut content analysis (along with stable isotope analysis and behavioural observations) has showcased a highly complex dietary network.

To digest this extreme complexity and surmount the hurdle of dietary unknowns, researchers frequently lump fishes into broad trophic categories, such as ‘mobile herbivores’. Broad generalisations are pragmatic and may be help us detect broad ecological trends, but they oversimplify species’ actual dietary preferences. As coral reefs are changing due to anthropogenic disturbances, it’s critical to thoroughly examine how well trophic groupings capture dietary linkages among reef organisms. Continue reading

Early Spring: Predicting Budburst with Genetics

Below is a press release about the Methods in Ecology and Evolution article ‘On the importance of accounting for intraspecific genomic relatedness in multi‐species studies‘ taken from the Université de Montréal.

Bud of American beech (Fagus grandifolia). ©Tim Savas

Researchers from Canada and the USA found that tree and shrub genetics can be used to produce more accurate predictions of when leaves will burst bud in the spring. Their study was published in Methods in Ecology and Evolution.

Although climate sceptics might find it hard to believe with this year’s endless snow and freezing temperatures, climate change is making warm, sunny early springs increasingly common. And that affects when trees start to leaf out. But how much?

Simon Joly, biology professor at Université de Montréal and Elizabeth Wolkovich, an ecology professor at University of British Columbia, showed that a plant’s genetics can be used to produce more accurate predictions of when its leaves will burst bud in spring. Continue reading

Introducing fishtree and fishtreeoflife.org

This post was originally published on Jonathan Chang’s blog.

In our recent publication (Rabosky et al. 2018) we assembled a huge phylogeny of ray-finned fishes: the most comprehensive to date! While all of our data are accessible via Dryad, we felt like we could go the extra mile to make it easy to repurpose and reuse our work. I’m pleased to report that this effort has resulted in two resources for the community: the Fish Tree of Life website, and the fishtree R package. The package is available on CRAN now, and you can install it with:

install.packages("fishtree")

The source is on GitHub in the repository jonchang/fishtree. The manuscript describing these resources has been published in Methods in Ecology and Evolution (Chang et al. 2019).

Continue reading

The babette R Package: How to Sooth the Phylogenetic BEAST2

Post provided by Richel Bilderbeek

 What is babette?

‘babette‘ is an R package that works with the popular phylogenetic tool BEAST2. BEAST2 uses one or more alignments and a model setup to create a Bayesian posterior of jointly estimated model parameters and phylogenies.

babette lets you call BEAST2 from an R script. This makes it easier to explore models and/or alignments than using the graphical user interface programs that BEAST2 provides. It will also help you to improve the reproducibility of your work with BEAST2.

babette Tutorial Videos

If you’re new to phylogentic analyses, the video ‘babette demo‘ demonstrates the package. It has all of the information that you need to be able to start using the package

Continue reading

Phylogenies, Trait Evolution and Fancy Glasses

Post provided by Daniel S. Caetano

Phylogenetic trees represent the evolutionary relationships among different lineages. These trees give us two crucial pieces of information:

  1. the relationships between lineages (which we can tell from the pattern of the branches (i.e., topology))
  2. the point when lineages separated from a common ancestor (which we can tell from the length of the branches, when estimated from genetic sequences and fossils).
Phylogeny of insects inferred from genetic sequences showing the time of divergence between ants and bees.

Phylogeny of insects inferred from genetic sequences showing the time of divergence between ants and bees.

As systematic biologists, we are interested in the evolutionary history of life. We use phylogenetic trees to uncover the past, understand the present, and predict the future of biodiversity on the planet. Among the tools for this thrilling job are the comparative methods, a broad set of statistical tools built to help us understand and interpret the tree of life.

Here’s a Tree, Now Tell Me Something

The comparative methods we use to study the evolution of traits are mainly based on the idea that since species share a common evolutionary history, the traits observed on these lineages will share this same history. In the light of phylogenetics, we can always make a good bet about how a species will look if we know how closely related it is to another species or group. Comparative models aim to quantify the likelihood of our bet being right and use the same principle to estimate how fast evolutionary changes accumulate over time. Continue reading

RPANDA: A Time Machine for Evolutionary Biologists

Post provided by HÉLÈNE MORLON

Yesterday saw the start of this year’s annual Evolution meeting and to celebrate Hélène Morlon has written a blog post discussing the amazingly versatile RPANDA package that she is developing with her research group. A description of RPANDA was published in the journal earlier this year and, like all our Applications papers, is freely available to read in full.

If you are attending Evolution, as well as attending the fabulous talks mentioned by Hélène below, do stop by booth 125 to see our BES colleague Simon Hoggart. Simon is the Assistant Editor of Journal of Animal Ecology and would be happy to answer your questions about any of our journals or any of the other work we do here at the BES.

RPANDA: a time machine for evolutionary biologists

Imagine “Doc”, Marty’s friend in Back to the Future, trying to travel back millions of years in an attempt to understand the history of life. Instead of building a time machine from a DeLorean sports car powered by plutonium, he could dig fossils, or more likely, he would use molecular phylogenies.

Molecular phylogenies are family trees of species that can be built from data collected today: the genes (molecules) of present-day species (Fig 1). They are often thought of as trees, in reference to Darwin’s tree of life. The leaves represent the present: species that can be found on Earth today. The branches represent the past: ancestral species, which from time to time split, giving rise to two independent species. The structure of the tree tells us which species descend from which ancestors, and when their divergence happened.

birds_phylog

Fig 1: The phylogenetic tree of all birds (adapted from Jetz et al. 2012). Each bird order is represented by a single bird silloutter and a specific colour (the most abundant order of Passeriformes, for example is represented in dark orange). Each terminal leaf represents a present-day bird species, while internal branches represent the evolutionary relationships among these species.

Continue reading

Introducing Biodiverse: Phylodiversity Made Easy

Post provided by SHAWN LAFFAN and ANDREW THORNHILL

© Shawn Laffan

© Shawn Laffan

Phylodiversity indices are increasingly used in spatial analyses of biodiversity, driven largely by the increased availability of phylogenetic trees and the tools to analyse them. Such analyses are integral to understanding evolutionary history and deciding where to allocate conservation resources.

Phylogenetic Indices: The Current Favourites

The most commonly used phylogenetic index is Faith’s Phylogenetic Diversity (PD; Faith 1992). PD is the phylogenetic analogue of taxon richness and is expressed as the number of tree units which are found in a sample.

More recently developed phylodiversity indices adapt the calculation of PD by adjusting the branch lengths of a sample using the local lineage range sizes and abundances, for example Phylogenetic Endemism (PE) and Abundance weighted Evolutionary Diversity (AEDt). In PE the length of each branch in a sample is multiplied by the fraction of its total geographic range found in that sample. The AEDt index uses the same general approach, but weights each branch by the fraction of total abundances found in the sample. The weighting process is generic, so one can scale the branch lengths by any relevant factor, for example the threat status (Faith 2015). Continue reading

What method has transformed your field the most, during your career?

In the 4th and final installment of Barb Anderson’s INTECOL 2013 podcasts, she asks a number of delegates: What method has transformed your field the most, during your career?

The answers in this podcast are given by the following people:

  1. Steve Hubbell, University of California, Los Angeles, USA (00.21)
  2. Georgina Mace, University College London, UK (00.44)
  3. Carsten Dormann, University of Freiburg, Germany (01.07)
  4. Continue reading

New Video – SURFACE: Detecting convergence with stepwise AIC

SURFACEIn Methods’ latest video, Travis Ingram gives a brief introduction to the new phylogenetic comparative method SURFACE. This method uses stepwise AIC to fit a series of stabilizing selection models to a phylogenetic tree and trait data, and to quantify the extent of convergent evolution toward the same selective regimes. The tutorial explains how SURFACE works, and then shows an example analysis in R.

You can view the video here, read the accompanying article here, download the R package from CRAN here, and download a tutorial with worked R examples here.

Diversitree video – starring Mr Blueberry and Fairly-Small-Yellow-Bird

Method’s latest video, “Diversitree”, is now available to view on our YouTube channel. In this quirky demonstration, Mr Blueberry and Fairly-Small-Yellow-Bird disagree on how colour affects the diversification of birds. Rich FitzJohn shows them how to
test their hypotheses using the comparative phylogenetic methods
implemented in the R package “diversitree”, recently described in the Methods paper “Diversitree: comparative phylogenetic analyses of diversification in R“. This article is one of Method’s freely available applications, which aim to provide a source of citable descriptions of new methods and techniques in ecology and evolution.

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