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Large Scale Patterns of Diversity

     NEON Invertebrate By-Catch The National Ecological Observatory Network (NEON) is a continental-scale ecological observatory that collects arthropods using pitfall traps at 47 sites in 23 states and Puerto Rico. From these traps, they measure abundance and diversity of ground beetles (the Carabidae). My current project is to develop nondestructive and semi-automatic methods to quantify the abundance, biomass and diversity of all ground-active arthropods collected in the NEON pitfall traps (aka "invertebrate bycatch"). These methods will lead to our having the ability to test ecological and biogeographical hypotheses across multiple taxa (e.g., spiders, ants, snails, worms, other beetle families, etc.) collected in a standardized fashion from the same places.

We are developing whole-trap imaging methods where we place invertebrate by-catch on white ceramic tiles. We then use a high resolution camera to capture the trap contents. From these images we can (generally) identify individuals to taxa. For example, the picture to the left is of an entire trap taken from Klemme Experimental Range in Oklahoma. Zooming in on the image we can readily identify many of the taxa, at least to family. The ant in the red box is a screen capter of the blown-up (1600 times) original image and we can readily identify it to Pogonomyrmex occidentalis. Using existing software (FIJI) we can extract linear and areal measures of body size for each individual in the image. Thus we can measure the abundance, body-size distributions and total biomass of the entire trap as well as the various taxa. In collaboration with Katie Marshall (University of British Columbia), we will develop machine-learning algorithms to automate the identifications, at least to taxonomic order.

In collaboration with Cam Siler and Matt Miller (University of Oklahoma), we are meta-barcoding the invertebrate by-catch by filtering the storage ethanol and extracting DNA directly from the filter. Thus, we can (relatively) quickly and non-destructively extract DNA from the trap contents by performing extractions on the filter. The DNA is then amplified and sequenced. Katie Marshall, Cam Siler and Matt Miller then use informatics techniques to link the sequence with taxonomic identities. This list of taxa can then be used iteratively to improve the taxonomic resolution for the images.

NEON Ants (NEON Blog post about our project HERE). - Funded by an NSF EAGER award, this project will study the activity, abundance and diversity of ants from National Ecological Observatory Network (NEON) sites. This work encompasses multiple spatial (e.g., trap, plot, NEON site, continent) and temporal (bi-weekly, annual) scales. The goal is to create baseline models of how climate impacts seasonal patterns of ant abundance, activity and diversity to parameterize predictive modesl of future abundance and diversity under climate change.

Long-term dynamics of ant abundance and diversity- As part of the NSF EAGER, I will re-sample ant assemblages on transects we sampled in the early 1990s. Using climate data collected at the research sites (many are LTERs and other research stations) as well as interpolated climate data, we will test how recent climate change has impacted activity, abundance and diversity of ants. Collaboration with M. Kaspari (OU).

How are diversity gradients generated and maintained?

The "canonical" Latitudinal Diversity Gradient ("LDG"), where a taxon has highest species richness at the equator which then declines toward higher latitudes, is considered a fundamental pattern of biogeography. There are several standing hypotheses that attempt to explain latitudinal diversity gradients. As these hypotheses were erected to explain the observed pattern (i.e., the observed LDG), they are non-exclusive and typically share predictions. Therefore, progress depends on testing secondary predictions of diversity hypotheses as well as exploring how diversity gradients vary within and amongst taxa. As such, my approach is to test both the primary and secondary predictions of mechanistic hypotheses of the LDG.

Current Projects

Most plant families do not contribute to the latitudinal gradient in species richness We used species richness data from 245 local vascular plant floras to quantify the slope and shape of the latitudinal gradients in species diversity (LGSD) across all plant species as well as within each family and order. We calculated the contribution of each family and order to the empirical LGSD. We observed the canonical LGSD when all plants were considered with floras at the lowest latitudes having, on average, 451 more species than floras at the highest latitudes. When considering slope alone, most orders and families showed the expected negative slope, but 31.7% of families and 27.7% of orders showed either no significant relationship between latitude and diversity or a reverse LGSD. Latitudinal patterns of family diversity account for at least 14% of this LGSD. Most orders and families did not show the negative slope and concave-down quad-ratic shape expected by the pattern for all plant species. A majority of families did not make a significant contribution in species to the LGSD with 53% of plant families contributing little to nothing to the overall gradient. Ten families accounted for more than 70% of the gradient. Two families, the Asteraceae and Fabaceae, contributed a third of the LGSD. The empirical LGSD we describe here is a consequence of a gradient in the number of families and diversification within relative few plant families. Macroecological studies typically aim to generate models that are general across taxa with the implicit assumption that the models are general within taxa. Our results strongly suggest that models of the latitudinal gradient in plant species richness that rely on environmental covariates (e.g. temperature, energy) are likely not general across plant taxa. PAPER   DATA 1 DATA 2

How (and why) diversity gradients differ across taxa- Funded under the NSF Macrosystems Biology Program the Experimental Macroecology project focuses on understanding the relationships between temperature and macroecological pattern and process. My work with this group focuses on diversity patterns across archaea,bacteria, fungi, soil arthropods and trees in collaboration with: J.H. Brown (U. New Mexico), B.J. Enquist (U. Arizona), M. Kaspari (OU), R.B. Waide (U. New Mexico), J. Zhou (OU)

     How (and why) diversity gradients differ within taxa- Diversity hypotheses that invoke mechanisms relating environmental factors such as climate on diversification rates have an implicit assumption that the mechanism is acting on all, or at least most, of the clades within a taxon. To simplify, generality of mechanism should lead to generality of pattern. I study the diversity gradients both across and within taxa to test this assumption and examine how taxonomic scale affects diversity patterns. Importantly, this method allows tests of hypotheses of pattern that allows rejection of specific taxon by gradient diversification hypotheses.

    Spatial patterns of functional trait diversity - I use biodiversity informatics tools to integrate plant species distribution with databases of plant size, morphology and functional traits. In collaboration with plant functional ecologists, I have examined the distribution of plant functional trait diversity across spatial scales from individual plots to comparisons of continents.

I am also part of a nascent collaborative network building a global database on ant life history and functional traits. My database on ant morphometrics (>60,000 linear measures of >3,000 ant species) is the core of the morphology database. Integrating this database with GABI (see below) will allow us to test hypotheses about global patterns of ant functional diversity.

Biodiversity Informatics

Tests of diversity hypotheses at continental to global scales require data that is broad in spatial scope yet fine-grained in resolution. While there is such data for a few vertebrate groups, I use a biodiversity informatics approach where I compile, integrate and analyze large-scale spatially explicit biodiversity databases.

Current Projects

    Global Ant Biodiversity Informatics Project- I co-founded (with Benoit Guénard and Rob Dunn at NCSU) a collaborative biodiversity informatics project collecting distribution data on and producing species level range maps for North American ants. This project has evolved into GABI, the Global Ant Biodiversity Informatics project, which is now producing maps of the known distributions of all ~15,000 ant species via antmaps.org .

    SALVIAS- I co-founded (with Brad Boyle and Brian Enquist) a global plant biodiversity informatics network called SALVIAS ( www.salvias.net). Funded by the Center for Applied Biodiversity Science at Conservation International, SALVIAS merged spatial and taxonomic data from millions of herbarium specimen and thousands of local plant inventories to study plant ecology and biogeography at continental, hemispheric and global scales.

Databases (just ones I can share, let's chat)

Most of the databases I work with are housed in a MySQL database with web accessible PHPMyAdmin front end. They are accessible by r scripting using the libraries DBI and RMySQL.

    FIA- I have a local copy of (parts of) the U.S. Forest Service Forest Inventory and Analysis Database (last updated January of 2015). For more information on the FIA, click here .