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About

I am an ant ecologist working in Texas. I am focusing on the Comanche harvester ant which lives in very deep sandy prairies surrounded by oak forests. I grew up in Virginia and have lived and studied in several other countries including 4 years in South Korea.

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:

Ants as Ecosystem Engineers

Comanche harvester ant (Pogonomyrmex comanche) nest year

Comanche harvester ant (Pogonomyrmex comanche) nest year

Many ant species are ecosystem engineers. An ecosystem engineer is an organism which structures the environment to suit its needs and in doing so has profound effects on the occurrence, abundance, and spatial pattern of other species. Beavers, who turn streams into ponds, are the textbook example. Ants do exactly the same thing in soil. They are soil engineers. Through their nesting habits, ants are agents of bioturbation, mixing soil horizons and creating avenues for water and gas exchange through the tunnels and chambers that make up their nest architecture. These activities result in soil production and altering soil chemical, physical, and biotic profiles.

nest casts

Their movement of materials from above and below ground concentrates nutrients and minerals in the nest and associated soil. The above ground nest structure is engineered as well. By creating soil or other mound structures, the ants may prevent plant colonization and change soil temperature and moisture profiles. The addition of pebbles to nest mounds done by Pogonomyrmex barbatus and P. rugosus, for instance, changes the temperature of the upper region of the nests. These species intentionally forage pebbles from the environment to do so. The parasitic, commensalist and mutualist organisms which may share these nests change the soil communities since these species would not be present at all without the ants.

Todd Island (TI-1) site at the Fort Worth Nature Center, Fort Worth, Texas. Note the Comanche harvester ant nest in the bare area, lower left.

Todd Island (TI-1) site at the Fort Worth Nature Center, Fort Worth, Texas. Note the Comanche harvester ant nest in the bare area, lower left.

Through all these activities ants engineer the soil to be suitable for the internal environment of their nests insuring the development of their young and their own survival. Because of this soil engineering, the occurrence, abundance, and spatial pattern of soil organisms and therefore the soil community are significantly different in areas with ant nests and those without. In turn, the differences in the soil community affect soil nutrient cycling and availability which affects these communities as well as the plant community which has a large portion of their bodies above ground. When an ant colony dies or moves, the nest area becomes available for colonization. As a result of the far reaching impacts of their engineering, ants have been used as indicators of ecosystem health and function, specifically tracking the progression through climax stages and in remediation of mining sites specifically due to soil production and engineering activities of ants.

The external nest of a Comanche harvester ant. The ants remove any plants from this nest yard area.

The external nest of a Comanche harvester ant. The ants remove any plants from this nest yard area.

Here I have focused mostly on the engineering of ground nesting ants on soil and provided photo of Pogonomyrmex comanche nests. Ant engineering may include many other ant species and other ecosystem impacts such as foraging activities including vegetation clearing on foraging areas and trails and foraging on seed and vegetative parts through which ants can impact plant populations and communities.

Because ants are central place animals, like beaver, their engineering is of local significance and contributes to the importance of spatial ecology for understanding ecosystem function and health.

 

Selected Literature

Andersen, A.N. 1990. The use of ant communities to evaluate change in Australian terrestrial ecosystems: a review and a recipe. Proceedings of the Ecological Society of Australia 16: 347 – 357.

Bucy, A. M. and Breed, M. D. 2006. Thermoregulatory trade-offs result from vegetation removal by a harvester ant. Ecological Entomology 31: 423 – 429.

Carlson, S. R. and Whitford, W. G. 1991. Ant mound influence on vegetation and soils in a semiarid mountain ecosystem. American Midland Naturalist 126: 125 – 139.

Cox, M. G. and Blanchard, G. B. 2000. Gaseous templates in ant nests. Journal of Theoretical Biology 204: 223 -238.

Dean, W. R. J., Milton, S. J., and Klotz, S. 1997. The role of ant nest-mounds in maintaining small-scale patchiness in dry grassland in Central Germany. Biodiversity and Conservation 6: 1293 – 1307.

de Bruyn, L. A. L. 1999. Ants as bioindicators of soil function in rural environments. Agriculture, Ecosystems, and Environment 74: 425 – 441.

Dostal, P., Brezniva, M., Kozlickova, V., Herben, T. and Hovar, P. 2005. Ant-induced soil modification and its effect on plant below-ground biomass. Pedobiologia 49: 127 – 137.

Eldridge, D. J. 1993. Effects on ants on sandy soils in semiarid eastern Australia: local distribution of nest entrances and their effect in the infiltration of water. Australian Journal of Soil Research 31: 509 – 518.

Elmes, G. W. 1991. Ant colonies and environmental disturbance. In: The Environmental Impact of Burrowing Animals and Animal Burrows [Symposium of the Zoological Society of London 63]. Clarendon Press: Oxford, UK. p. 15 – 32. Clarendon Press: Oxford, UK.

Folgarait, P. J. 1998. Ant biodiversity and its relationship to ecosystem functioning: a review. Biodiversity and Conservation 7: 1221 – 1244.

Hendricks, P. and Hendricks, L. M. 1999. Field observations on the myrmecophilous beetle Araeoschizus airmeti Tanner (Coleoptera: Tenebrionidae) at harvester ant mounds (Hymenoptera, Formicidae) mounds. Great Basin Naturalist 59: 297 – 299.

Lesica, P. and Kannowski, P. B. 1998. Ants create hummocks and alter structure and vegetation of a mountain fen. American Midland Naturalist 139: 58 – 68.

MacMahon, J. A., Mull, J. F., and Crist, T. O. 2000. Harvester ants (Pogonomyrmex spp.): their community and ecosystem influences. Annual Review of Ecology and Systematics 31: 265 – 291.

New, T. R. 2000. How useful are ant assemblages for monitoring habitat disturbance on grasslands in south eastern Australia. Journal of Insect Conservation 4: 153 – 159.

Nikem, J. N., Lobry de Bruyn, L. A., Grant, C. D., and Hulugalle, N. R. 2000. The impact of ant bioturbation and foraging activities on surrounding soil properties. Pedobiologia 44: 60 9 – 621.

Pisani, G. R. 2009. Use of an active ant nest as a hibernaculum by small snake species. Transactions of the Kansas Academy of Science 112: 113 – 118.

Ríos-Casanova, L. Valiente-Banuet, and A., Rico-Gray. 2006. Ant diversity and its relationship with vegetation and soil factors in an alluvial fan of the Techuacán Valley, Mexico. Acta Oecologica 29: 316 – 323.

Smith, C. C. 1940. Biotic and physiographic succession on abandoned eroded farmland. Ecological Monographs 10: 421 – 484.

Snyder, S. R. and Friese, C. F. 2001. A survey of arbuscular mycorrhizal fungus root inoculums associated with harvester ant nests (Pogonomyrmex occidentalis) across the western United States. Mycorrhiza 11: 163 – 165.

Trager, J. C. 1990. Restored prairie colonized by native prairie ants (Missouri, Illinois). Restoration and Management Notes 8: 104 – 105.

Underwood, E. C. and Fisher, B. L. 2006. The role of ants in conservation monitoring: if, when, and how. Biological Conservation 132: 166 – 182.

 

Comanche Harvester Ant Harvests Yucca Seeds

Despite not being recognized by the Parks and associated Friends of the Southwest Nature Preserve in Arlington, Texas (And I have brought this to their attention), the Comanche harvester ant (Pogonomyrmex comanche) is an important part of the ecology of the Glen Rose Yucca Prairie.

This is a small prairie with about 60 Comanche harvester ant colonies.

This is a small prairie with about 60 Comanche harvester ant colonies

There are about 60 colonies in this 4.43 ha meadow.Comanche is generalist seed predator and when the Yucca are releasing their seeds, the ants are harvesting them. I have seen some colonies with all foragers bringing Yucca seeds. So, the ants have the potential to impact the Yucca population.

This Comanche harvester ant is harvesting a Yucca seed in the Southwest Nature Preserve.

This Comanche harvester ant is harvesting a Yucca seed in the Southwest Nature Preserve.

Comanche in SWNP

 

Here is a Comanche nest in the Yucca Meadow: typically a cone shape with a central entrance — the soil is sandy.

Comanche harvester ant nest in the Yucca Meadow

There are many grass and forb plants which have seeds Comanche will forage. Here a forager is bringing back a snake cotton seed. Because of the many hairs on this seed, Comanche appears to use it like Velcro and sometimes collects other seeds with these hairs, thus bringing back more than one seed.

Comanche harvester ant collected  a snake cotton seed

Note the spread of her jaws or mandibles and how she has curled her body around toward the seed.

There are several Comanche nests in the trails at the Southwest Preserve as well. Some of these are quite a distance from the Yucca Meadow.

Comanche harvester ants congregating at their nest

Comanche harvester ants congregating at their nest

The above nest is near the meadow.

Comanche harvester ant nest in a trail

The above nest is in a trail far away from the Yucca meadow. None of the trail nests have as distinctive a crater form.

Finally, there is at least one Barbatus harvester ant colony in a trail at the Southwest Nature Preserve, not far from the Yucca Meadow. This colony has moved it locations a few times over the past 5 years.

Barbatus harvester ant colony

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

No Place Like Home: the Comanche Harvester Ant in the Cross Timbers

I had  a short paper published in the frist issue of Post Oak and Prairie Journal (January 2015). In this paper, I highlight some natural history work that did not make it into my dissertation on the Comanche harvester ant (Pogonomyrmex comanche). I plan to follow up on this work in the near future.

The paper is titled: No Place Like Home: the Comanche Harvester Ant in the Cross Timbers. (Notice that my photo of a Comanche harvester ant made the cover — such a great Cover Girl!)

The Cross Timbers Ecoregion occurs in Kansas, Oklahoma, Texas, and perhaps Arkansas, where the eastern forests grade into the drier western grasslands and desert. This region is characterized by a mosaic of oak forests and prairie — which is exactly the mosaic of habitats the Comanche harvester ant likes. I believe that the Comanche harvester ant is an important part of this ecosystem in part because they nest only in the prairie but forage into the woods, thereby connecting these different habitats. In the near future, I plan to investigate how Comanche and other ants play a role in this dynamic ecoregion.

 

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:

The Comanche harvester ant in the Southwest Nature Preserve

There is a population of 60 colonies of the Comanche harvester ant (Pogonomyrmex comanche) in a small prairie in the Southwest Nature Preserve in Arlington, Texas. I have been studying this population for several years – mapping the colony nest locations, observing their foraging, and testing nestmate discrimination.

Last week I discovered 4 Comanche colonies not in this prairie but in some of the trails in the preserve. There are also two colonies in the trail that goes by the prairie, separated by a line of trees and grass. Of these new colonies, I believe 3 are 3-4 years old and the other is 1-2 years old. It looked as though something or someone had tried to dig into the second and forth of these nests. I examined the areas around all these colonies but the only colonies were actually in the trails.

Locations of Comanche harvester ant colonies in the Southwest Nature Preserve. Note the colonies in green were located this year and are isolated from the main population in red.

Locations of Comanche harvester ant colonies in the Southwest Nature Preserve. Note the colonies in green were located this year and are isolated from the main population in red.

The colonies are probably located in the trails where the soil was more exposed — so easier for a queen to discern that the soil is sandy, easier to dig in, and lacking in much leaf litter and humus. These ants also use the established trail to start out their foraging journeys — this species does not make much use of pheromone trails but relies on vision for orientation.

Their presence in the trails is a bit intriguing. These colonies are separated by 150 – 440 meters and by dense forest from the population I have been studying. I wonder how these queens made it to these locations, how these queens choose their nest sites and how/if these colonies are (or will be — they might not be mature colonies and so not produce alates yet) involved in a mating lek with the colonies in the prairie. The mating of Comanche has not been studied and I have only some observations which suggest that it is different in timing and occurrence from Johnson’s (2000 and 20001) speculation on this species.

There was a lot of foraging going on at the Preserve on Sunday, May 11, 2014. Here are two digital recordings and photos of the Comanche colonies.

Photos of the 4 Comanche nests found in trails. All of these nests were about 30 – 50 cm in a rough diameter (that is, they were not completely round).

First Colony:

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Second Colony:

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Close-ups of the two entrances for the second colony (Full photo above):

Close-up of one nest entrance for Comanche colony 2        Close-up of the other entrance of Comanche colony 2

Third Colony:

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Forth Colony:

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Comanche harvester ant (Pogonomyrmex comanche) colony in a trail at the Southwest Nature Preserve, Arlington, Texas

Here is a digital recording of some Comanche foragers (third colony) getting a scavenged bee into their nest, The little black ant that comes in at times is an acrobatic ant (Crematogaster). This recording is about 10 minutes.

Finally, here is a digital recording of pollinators and pollen eaters in a prickly pear blossom (about 1 minute):

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.