Category Archives: Research

This category includes all my research projects.

The Spatial Ecology of the Comanche Harvester Ant

I have successfully presented my dissertation work and am currently finishing up the revisions for the final submission to the University of Texas at Arlington for the PhD degree. I expect the final dissertation to be available from the university library by July 2015.

The title of the dissertation is: The Spatial Ecology of the Comanche Harvester Ant, Pogonomyrmex comanche (Hymenoptera, Formicidae)

Dr. Esther Betran was the chair of my committee (UTA).

Other committee members were:

Dr. Jonathan Campbell (UTA)

Dr. Paul Chippindale (UTA)

Dr. Sophia Passy (UTA)

and Dr. Walter Tschinkel (FSU)

Here is the slide presentation and the notes which are numbered to correspond to the slides. I have included some of the corrections that came out of the discussion with my committee and otherwise have noted where there are other problems which I am addressing in the revision.

The slides:

and the notes:

Comanche harvester ant colony location maps

The following are maps of colony locations and abundance/density in my study sites in the Fort Worth Nature Center and Southwest Nature Preserve. You can get an idea of the abundance, density, and location changes.

 

Locations in EP:

 

Colony location in EP, 2009 - 2013

Colony location in EP, 2009 – 2013

Locations in GL:

 

Pogonomyrmex comanche colony locations in the GL of the FWNC, 2010 - 2013

Pogonomyrmex comanche colony locations in the GL of the FWNC, 2010 – 2013

Locations in T1P;

T2P_composite

Locations in T2P:

 

Comanche Harvester Ant Colony Locations in T1P

Comanche Harvester Ant Colony Locations in T1P

Locations in SP

Colony locations in SP from 2011 - 2013

Colony locations in SP from 2011 – 2013

Comanche Harvester Ants are Pansies!

As part of investigating nestmate discrimination, I decided to test if Comanche can distinguish other ant species. So I ran behavioral trials between the Comanche harvester ant (Pogonomyrmex comanche) and the Barbatus harvester ant (or harvester ants or big red ants, Pogonomyrmex barbatus) and: !

Comanche are pansies — mostly they did nothing, either in arenas with P. barbatus or when P. barbatus was introduced to their nest mound near the entrance. In fact, P. barbatus sometimes entered the nest seemingly without harm since they also returned to the external nest.

Out of 19 arena encounters, there were 4 with any aggression and only one of these had an extended grabbing encounter. Barbatus was always the aggressor.

Out of 14 on the nest encounters, 2 showed some aggression by Comanche, mostly a kind of harassment. Mostly, Barbatus just left the mound though twice barbatus entered the nest. Once Barbatus showed great difficulty maneuvering over the sandy mound.

All trials were recorded with a camcorder so I am still analyzing them.

 

Prairies in a Changing World: State of the Prairie Conference 2014

Conferene poster

The Native Prairies Association of Texas (and the Coastal Prairie Partnership) had their annual meeting in Fort Worth at the Fort Worth Botanical Garden from May 29 – May 31, 2014.  I was invited to present my research on ants in the prairies of the Fort Worth Nature Center in Fort Worth and the Southwest Nature Preserve in Arlington, Texas.

I also attended most of the meeting and gained a lot from the presentations I attended and especially from hobnobbing with other attendees.

**I want to pass on that Native American Seed is producing a seed mix especially to attract native bees which will be available this fall. Here’s the link to this Seed Source.

Here is the agenda for May 30 and May 31, following which I post my notes on the few talks I was able to attend with some comments and finally my presentation and extensive notes on the slides.

May 30 Agenda

State of the Prairie Agenda for May 30

May 31 Agenda

State of the Prairie Agenda for May 31

My Notes and Comments

State of the Prairie Conference Notes

Demonstration Prairie 5

The Demonstration Prairie at the Fort Worth Nature Center (photo above)

I presented my research on the ant species I have found in 17 sites at the Fort Worth Nature Center and what this means for 1) the possibility of using ants as bioindicators and 2) for the ecology of the Cross Timbers Ecoregion.

“Jills of All Trades: Ant Diversity and Flexibility in the Cross Timbers Ecoregion”

Here are my notes. In these notes I include quite a bit more than I was able to cover, in part, so that if you did not attend, you can follow the slides. If you have questions, message me.

Jills of all Trades_Presentation Notes

And finally, I mention a 10 minute digital recording I made of the Comanche harvester ant “remodeling” a ground bee nest that was too close to the ant nest. Here is a the video:

Ant Presence and Abundance in the Fort Worth Nature Center

I sampled ants using pitfall traps in 17 sites in the Fort Worth Nature Center monthly in June, July, and August 2012.

I used CANOCO to run redundancy analyses (RDA) on ant presence with abiotic and biotic environmental variables and on ant presence and abundance with soil type to look for ant preference for soil. I used forward selection of variables and Monte Carlo significance tests to select the variables for the final RDA models.

RESULTS

1) RDA for ant presence and environmental variables

RDA Summary Table

Axes

1

2

3

4

Total variance

 Eigenvalues                     

0.122

0.062

0.026

0.014

1.000

Species-environment correlations

0.820

0.872

0.672

0.582

Cumulative percentage variance of species data

12.2

18.4

21.0

22.4

Cumulative percentage variance of species-environment relation 

51.5

77.6

88.8

94.5

Sum of all eigenvalues     

1.000

Sum of all canonical eigenvalues     

0.237

Triplot

2) RDA for ant presence and soil type

RDA Summary Table

Axes                                    1      2      3      4 Total variance
Eigenvalues

0.076

0.023

0.011

0.007

1.000

Species-environment correlations 

0.788

0.603

0.424

0.417

Cumulative percentage variance    of species data

7.6

9.9

11.0

11.7

Cumulative percentage variance    of species-environment relation 65.2   84.9   93.8 100.0
Sum of all eigenvalues

1.000

Sum of all canonical eigenvalues

0.117

Triplot

3) RDA for ant abundance and soil type

RDA Summary Table

Axes                                    1      2      3      4 Total variance
Eigenvalues

0.070

0.031

0.016

0.003

1.000

Species-environment correlations 

0.777

0.655

0.456

0.265

Cumulative percentage variance    of species data

7.0

10.1

11.7

12.0

Cumulative percentage variance    of species-environment relation

58.4

84.6

97.9

100.0

Sum of all eigenvalues

1.000

Sum of all canonical eigenvalues

0.120

Triplot

24% of species presence is explained by the environmental variables with percent litter cover and drainage being the significant variables. Sampling sites by date clumped together indicating a lack of seasonality — which seems a bit unusual since late July and August become quite hot and ant activity seems reduced  at this time.

12% of species presence was explained by soil type with the Aquilla soil being the only significant soil. This soil is the only soil type where the Comanche harvester ant (Pogonomyrmex comanche) is found. All other species are more generalist with respect to soil type.

7.4% of species abundance was explained by soil type again with the Aquilla soil being the only significant soil. This result further supports the result with species presence: only the Comanche harvester ant has such narrow soil preference.

CONCLUSIONS

Though the eigenvalues are low this is not unusual for ecological data. The low level of explanatory value of these variables is likely due to the generalist nature of these species (and more temperate species in general) and the below-ground nesting of most ant species.

The Comanche harvester ant (Pogonomyrmex comanche) was the only species to show strict preference for soil type. Exactly what this species’ preference or requirement is remains unresolved.

Prelimary Work on the Comanche Harvester Ant Colony Distribution

Here are two posters which summarize preliminary work on the distribution of nests of the Comanche harvester ant  (Pogonomyrmex comanche) in the Fort Worth Nature Center, Fort Worth Texas. The nests were located visually by walking through the habitat and locating nests and following foragers back to nests. Nests were then flagged and GIS coordinates recorded. Environmental variables, geospatial data, and co-occurring ant species (Forelius and Trachymyrmex turrifex) were also evaluated.

I am currently working through 5 years of this kind of data for my final dissertation project. In the  final project, I also have nest locations for a population in the Southwest Nature Preserve in Arlington, Texas.

From 2010: Nest Distribution of the Comanche Harvester Ant

 

From 2012: Tracking the Comanche Harvester Ant

 

Redundancy Analysis on Ant Assemblage Data

Here are the preliminary results of the first redundancy analysis (RDA) for all the sites sampled over the summer of 2012. I performed a PCA with only environmental variables and one with only species data to look for an underlying pattern — which was confirmed. Then I ran an RDA with the full set of environmental variables and species data to determine the most significant quantitative environmental variables. Here are the results of the final RDA for this set of data which includes samples from 21 sites sampled monthly over the summer.

The Summary Table:

Axes

1

2

3

4

Total variance

Eigenvalues

0.358

0.129

0.060

0.020

1.000

Species-environment correlations 

0.977

0.956

0.923

0.720

Cumulative percentage variance of species data               

35.8

48.8

54.7

56.8

Cumulative percentage variance of species-environment relation

61.8

84.1

94.4

97.9

Sum of all eigenvalues     

1.000

Sum of all canonical eigenvalues     

0.580

Marginal effects of environmental variables:

Marginal Effects

Variable Var. N Lambda1
LiC 2 0.32
BG 4 0.27
LA 6 0.21
ToC 3 0.17
SP 5 0.07

Conditional effects of environmental variables:

Conditional Effects

Variable

Var. N

Lambda A

P

F

LiC 2 0.32 0.002 25.00
LA 6 0.13 0.002 12.20
BG 4 0.07 0.002 7.90
ToC 3 0.04 0.002 4.68
SP 5 0.02 0.028 1.81
LiC 2 0.32 0.002 25.00

Ordination Plots:

Species and environmental variables:

Species and Sites:

2013 America’s Grasslands Conference Proceedings

This past summer, August 12-14, 2013, the National Wildlife Federation and Kansas State University teamed up to have the 2nd America’s Grassland Conference in Manhattan, Kansas. I attended this conference and presented some preliminary work on some ant assemblages in the Fort Worth Nature Center, Fort Worth, Texas. I am completing that project this spring as part of my dissertation.

The proceedings from the conference, America’s Grasslands: The Future of Grasslands in a Changing Landscape, is now available. A summary of my preliminary  work is found on page 41.

The conference was wonderful. I have several posts concerning this conference:

1) the 2013 America’s Grassland Conference: Synopsis and Notes

2) Flint Hills, Tallgrass Prairie, Chase State Fishing Lake and the Gallery at Pioneer Bluff Field Trip

3) Konza Prairie Biological Station

Environmental Variable PCA Results

Here are the results from PCA on all environmental variables measured with descriptive (dummy) variables used as supplementary. The analysis was run in CANOCO and generated the following ordination diagrams and summary tables. This is an initial analysis. (Sites are identified by number, measured variables are smaller text and thin blue arrows, and supplementary variables which are not used to construct the ordination axes are larger blue text with gray arrows.)

For all 21 sites and all dates sampled over summer 2011:

PCA Summary for ALL samples, sites, and dates
Axes 1 2 3 4 Total variance
Eigenvalues

0.597

0.207

0.087

0.059

1.000

Cumulative percentage variance of species data               

59.7

80.4

89.1

95.0

Sum of all eigenvalues     

1.000

 

Environmental variables from 21 sites in Fort Worth and Arlington, Texas from the whole summer

Environmental variables from 21 sites in Fort Worth and Arlington, Texas from the whole summer

For all 21sites sampled in August 2011:

PCA Summary for SUMMER samples, sites, and dates
Axes

1

2

3

4

Total variance

Eigenvalues

0.620

0.226

0.067

0.047

1.000

Cumulative percentage variance of species data

62.0

84.6

91.3

95.9

Sum of all eigenvalues

1.000

PCA diagram for the environmental variables of 21 sites in Fort Worth and Arlington, Texas

PCA diagram for the environmental variables of 21 sites in Fort Worth and Arlington, Texas

For all 17 sites and all dates sampled in the FWNC over the summer 2011:

PCA Summary for ALL FWNC samples, sites, and dates
Axes

1

2

3

4

Total variance

Eigenvalues

0.590

0.183

0.112

0.035

1.000

Cumulative percentage variance of species data               

59.0

77.3

88.5

92.1

Sum of all eigenvalues     

1.000

Environmental variables from 17 sites in the Fort Worth Nature Center, Fort Worth, Texas over the whole summer

Environmental variables from 17 sites in the Fort Worth Nature Center, Fort Worth, Texas over the whole summer

Compiled for all 17 sites sampled over the summer 2011 in the FWNC:

PCA Summary for Averaged FWNC samples, sites, and dates
Axes

1

2

3

4

Total variance

Eigenvalues

0.594

0.198

0.119

0.035

1.000

Cumulative percentage variance of species data

59.4

79.2

91.0

94.5

Sum of all eigenvalues

1.000

 

Environmental Variables PCA from 17 sites in the Fort Worth Nature Center, Fort Worth, Texas

Environmental Variables PCA from 17 sites in the Fort Worth Nature Center, Fort Worth, Texas

 

 

Stratford and Tandy Hills Prairie Ants

I am completing the ant identifications for the prairie and forest in the Southwest Nature Preserve in Arlington, Texas and the additional prairies, Statford  and Tandy Hills, in Fort Worth, Texas. I believe I have found another Temnothorax species which I have not been able to identify and another Pheidole species. This is quite exciting. No Pogonomyrmex ants are found in the Stratford or Tandy Hills Prairies.