Influence of human land use and invasive species on beta diversity of tropical ant assemblages

New paper from my PhD research is published in Royal Entomological Society's Insect Conservation and Diversity. 

Link to Full Paper: CLICK

Graphical Summary:

Plain Summary: 

1. 18 NEW additions to ants of Goa. 

2. Asian Weaver Ant is the most common and an important species in Goa, maintaining several important ecological functions. 

3. Human conversion of natural habitats will disrupt diversity and distribution of ants and will cause harm to ecosystem functions like nutrient cycling, decomposition, pest control and seed dispersion. 

4. Lateritic plateaus of Goa have diverse and unique ant fauna that perform several important ecosystem functions. Further conversion of lateritic plateaus for human use without proper management plans will affect human wellbeing. 

5. Five invasive species of ants are inching towards decimating local ant populations and affecting several critical ecosystem functions like decomposition and seed dispersal. Management of invasive ants, especially Yellow Crazy Ant, which is a globally important invasive, is going to become an important challenge for India.

Acadmic Abstract:

1. Understanding how biodiversity is distributed is increasingly becoming important under ongoing and projected human land use. Measures of beta diversity, and its partitions, can offer insights for conservation and restoration of biodiversity. 

2. We ask how different species, functional groups, and land use contribute to beta diversity, and whether invasive species have a negative influence on beta diversity. We address these questions using ant assemblages (Hymenoptera: Formicidae) at 277 sites distributed across five geomorphic land use types in Goa, India. 

3. We recorded 68 species (35 genera, 7 subfamilies) of which 5 were invasive. We classified them into eight functional groups. Oecophylla smaragdina—a common tropical arboreal species, and Anoplolepis gracilepis—a globally significant invasive, contributed the most to beta diversity. Large-bodied omnivores which may influence soil functions contributed more to beta diversity than small-bodied predators. Lateritic plateaus contributed most to beta diversity, whereas human-influenced plantations contributed the least. Beta diversity across sites was related to species turnover, whereas nestedness was more prominent for functional groups. This indicates how species replace one another with change in land use, but functional roles are lost despite such turnover. Sites with human land use had higher incidence of invasive species, and invaded sites contributed less to beta diversity than non-invaded sites. 

4. Human land use strongly influences diversity and distribution of ant assemblages. Land use may spare local species richness, but not functional groups. A small number of invasive species exert negative influence even in very speciose communities.

Common Ants of Karnataka

In November last year, I met the dynamic Karthikeyan Srinivasan, Chief Naturalist of Jungle Lodges and Resorts in the 1st Goa Bird Festival. Being part of the organising section of the festival I happened to interact with Karthikeyan under the shades of lush mangroves in Chorao Islands and discussed what I know best "ants". Conversation meandered towards JLR's blogs, stories and while at it, Karthikeyan suggested I do an article on "Ants of Karnataka". After much prodding and delay, I finally managed to write a two piece article on "Common Ants of Karnataka". The links are below. Do read!

Common Ants of Karnataka: Part 1

Common Ants of Karnataka: Part 2

Crematogaster rothneyi in a typical defensive position with venom at the tip of its sting 

Over the past year, I have been inconsistent in sharing my ant adventures, most of which have been very interesting. I hope to keep updating my blog regularly from now on with smaller informative pieces rather than a big post.

India Biodiversity Portal Community Meet 2016

It has been a long time since I have updated my blog, primarily because of me shifting to my new research facility at the Centre for Ecological Sciences at the Indian Institute of Sciences- Bangalore, India for my Ph.D and being busy with settling down. The past eight odd months have been very slow with absolutely no field work or even a chance to look through specimens under a microscope, but now things are slowly picking up and a lot of exciting things are coming my way. 

On 20th February 2016, I was invited to give a small presentation on Ten common Ants found in India to the users of the Citizen Science Initiative- India Biodiversity Portal. It was very interesting interacting with users and explaining to them about ants which didn't involve "ant extermination" thankfully! :D

A group photograph of all the participants of IBP-2016 Meet.

It was also fun meeting up with Dr.Priyadarshan and Dr. Rengaian Ganesan from ATREE and discussing about ants with them! 

Do look into this video of the 12 minute presentation on Common Ants of India. 

Might of the Ant Mite

"A mite makes the seas roar" Richard Feynman (1988) so reads the opening lines of Macromite’s Blog which is really mind-boggling considering the amount of information that has been compiled on this blog on these more so obscure subject!

Mites have not been a group I love especially because I have been prone to mite attacks every time I came out of the forests of the Mhadei in Goa which is part of the Western Ghats. I have never given them much of a thought except on few occasions. The first time I came across them was on the body of an electrocuted Indian flying-fox (Pteropus giganteus) which we had tried to preserve in my early days as a graduate student of Zoology. I was so excited about the prospects of performing taxidermy on the winged mammal that I almost overlooked the small creatures scampering around the dead flying-fox’s body, but once I did get a look at them, it took me more than fifteen minutes to actually pull out an individual from the flying-fox’s body. It was one mean looking individual. Back then, I did not show much interest and ended up mounting the specimen on a card point, leaving it in a specimen box which eventually got lost thanks to renovation activities of my erstwhile institution. 

Probable specimen of Cyclopodia horsfieldi from Pteropus giganteus (Lateral View)

Probable specimen of Cyclopodia horsfieldi from Pteropus giganteus (Dorsal View)

Read more about ectoparasites of Flying Foxes.

Years from then though, I was lucky to catch a glimpse of them on the subjects I love the most “ANTS”. I was aware of parasitism in ants and had been under the notion that ectoparasites usually affect big sized ant species and that perception went for a toss when I saw what I saw. 

Just before pulling the curtains on my stint at Pondicherry University, I was attending a dinner party at my friend’s place when I happened to see 20 medium sized ants milling around a crack on the floor tiles. A closer examination revealed they were queens of the invasive Monomorium pharaonis (Linnaeus, 1758). This species of Monomorium live as populous polygynous (a typical ant colony has just one queen but there are species where a colony may have many queens living together and such colonies are called polygynous) colonies which can survive on almost anything as a resource. This generalist behavior of theirs has made them quite successful and they according to me were someone who could never be subjected to any misery, but what I saw that day changed this perspective off mine. 

Affected Monomorium pharaonis queens and workers

A closer observation revealed small bumps covering the entire body of the queens. The workers too had these bumps all over their body. The colony appeared to be shifting but they were disoriented and unorganized. The workers seemed to be moving around in circles while the queens just lay there doing nothing. Occasionally a queen would start jerking violently but it lasted only a few seconds. The entire scene was dramatic and unlike anything I had ever seen previously.

All I could do was take a few pictures that day and move on from there with the threat of becoming an anti social-gathering individual looming on my head. 

Affected Monomorium pharaonis queens and workers

Close up showing mites attached through out the body of the queens. Also seen mites infecting the entire body of the worker at the bottom left.

Later I did try to search for instances of observation on mite parasitism on Monomorium pharaonis but I kept meeting dead ends. A paper titled “The diversity and host specificity of mites associated with ants:the roles of ecological and life history traits of ant hosts” by K. U. Campbell, H. Klompen and T. O. Crist in Insectes Sociaux gives a list of 151 mite species identified from 43 species of ants from Ohio but there is no mention of the Monomorium pharaonis. It seems that either there is nothing much on this in the public domain or my “googling” skills are very poor. Both ways this observation is very interesting and warrants some PhD student’s in-depth attention. Is anyone willing to take that offer?

How to Identify Ants? (Part1)

Let us get it straight, ants are damn small, dull and potentially offensive due to their bites and stings. They are small enough to hide most of their beautiful features and that is a primary reason why every ant is either a black ant or a red ant to a common man. Added to this the woeful childhood experience of been stung or bitten by some pugnacious ant, again goes against the image building of this group. Compare that with a butterfly. They are big (bigger than ants), are extremely colourful in most cases and catch our attention instantly. It is as if they are walking PR stunts and to top it off are associated mostly with love and romance (No offence  my lepidopterist friends)! The below image explains this well.

Comparison of Jerdon's Jumping ant and Common Imperial butterfly photographed at 150mm

The game though entirely changes when you zoom in a bit on ants (optically). Those fine ridges, striations, spines, pubescence and other wonderful morphological features that are usually not seen to the normal human vision becomes evident.

Jerdon's Jumping ant | Harpegnathos saltator (T. C. Jerdon, 1851) seen at a 1:1 zoom ratio at 90mm

Till a few years ago, this wonderful group was restricted only to a few who had access to microscopes but with the advent of macro photography both at the higher and at lower end, people have started to show their interest towards ants. They are able to appreciate the world of this hitherto neglected group more and the levels of curiosity are on a steady rise. No more is this the domain of just educational/ research institutes in India, since a new breed of enthusiasts are coming up just on the lines of birdwatchers and the term ant watchers doesn't sound very bad either!

Few days ago an online friend Deepak Deshpande on an online forum, asked me “how to go about identification of ants?” For almost three days I have been constantly thinking, how best do I answer to him and then thought about attempting to make a series of posts which will help in identification of ants to a basic level. This post, which will be the first of the series, will have a general description about ant taxonomy and steps to identify ants till sub-family level.

Before I start, I would like to drop in a few lines regarding the general position of ants in the animal kingdom. I will assume that most of you know general biology but still I have tried to make it as simple as possible and will start with the systematic position.

Systematic position of ants in Animal Kingdom.

Many have also asked me if ants are related to bees or wasps and the below diagram will be useful in understanding that.

Phylogeny of order Hymenoptera

The next question to address is how to differentiate ants from wasps or bees? There are three distinct features which an ant has and distinguishes it from its cousins the wasps and the bees, they are: geniculate/ elbowed antenna, metapleural gland and a petiole which separates the thorax from the abdomen. The below diagram will be useful for to visualize these features better.

Characteristic features of an Ant

For a more detailed and descriptive sketch of the morphology of an ant refer to the below image:

Ant Morphology

Looks scary right? So let us start with some very basic parts of an ant which we will be using in trying to key them down till subfamily level.

Ant Morphology for Beginners (side profile)

Ant Morphology for Beginners (head)

Now that we are familiar with the basic parts of ants, let us attempt the next step. What follows below is a simple key to identify ants till subfamily level. 

Instructions for use:
Look at your photograph of any ant closely and read the first line of this key. 
If the description matches that of what is in your photograph go the the next numbered line which is mentioned in the brackets. 
Please note that there are 10 subfamilies of ants described from India and this post will help you identify only the 5 most encountered subfamilies.

First glance through this post and you will think this is extremely tough and you might also be feeling that you probably wasted your time, but believe me this is very rewarding if you are genuinely interested.

There is another short cut way to identify ants and that is to use a picture guide. The best pictorial field guide as of now in the market is “On a Trail With Ants– A Handbook of The Ants of Peninsular India by Ajay Narendra and Sunil Kumar M” which has around 50 common species photographed and described in it. 

But as an afterthought if you are serious about identifying ants, the best thing to do is get familiar with taxonomic keys because a pictorial field guide for ants will limit you to only what is represented in the guide while going systematically using keys will open up the world of ants for you with almost no restrictions.

Before I conclude this section, just a few words of suggestions:

• You need patience and perseverance to develop necessary skills for identification and taxonomy of not only ants but any other taxa in the living world, be it the humble grass or the charismatic tiger.
• Regular exposure to this taxon (ants) is what will get you there.
• Colour is not a very good tool for identification when it comes to ants and hence there is no black or red ant.
• Always remember that every statement/ natural history observation will always have an exception so be open to surprises.
• Nothing in natural history studies is full and final; there is always scope for learning in even the most widespread and commonest observations.

Please do give me your suggestions if you found this useful or if you need any edits to be made which will make it more easy.