Termite nest architecture: extended superorganisms? Paul Eggleton

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1 Termite nest architecture: extended superorganisms? Paul Eggleton

2 Synopsis

3 Synopsis Review of mound structures and their functions Concentrate on Macrotermes What makes up a termite colony? How does the colony function? What sort of entity is it?

4 Termite architecture Most complex, non-anthropogenic, constructions Complex functions Integrated part of a colony

5 A few examples of colony structures

7 Definitions Almost all building material are constructed from faeces. The nest is where the colony lives, and is often made from woody faeces, but may not be easy to delineate The mound covers the nest and has a protective function. It is always made from soil usally from faecal soil but sometimes from subsoil transported by workers.

8 Functions of nests and mounds Protection from rainfall

9 Protection Nests seem to be defended in four ways: Walls Strong point defence Counter-attack defence Labyrinth defence

11 Defending the interior: tunnels Block tunnel and crush or concuss = Strong Point

12 Cryptotermes Phragmotic crushing Pericapritermes Energy storing concussion

14 Defending the exterior: the nest Recruit to the surface and then kill, often using chemical defences. Counter attack

15 Acanthotermes Nasutitermes Slice Squirt

16 Daubing brush Rhinotermes

17 Defending nests: the labyrinth Coptotermes Queen and soldiers Energy required to find the Queen may be greater than any energy acquisition.

18 Homeostasis Ventilation Gas exchange Moisture control

19 Macrotermes The most extreme example and the one that shows all the elements of the colony as organism One of the most organisationally complex biological system in the world

20 Evolution of fungus-growers complexity and serial mutualism 1 Blattid Gut flagellates Termitomyces Gut flagellates Cryptocercus 2 Wood-feeding termite 3 Fungus-growing termite 1. Wood-feeding, gut flagellates (in ancestor of Cryptocercus and termites) 2. Eusociality (sterile castes, permanent colonies) 3. Externalisation of gut, gain of fungus, loss of flagellates,

23 Lamellar flow

24 Thermosiphon

25 Eastgate Centre, Harare, Zimbabwe

26 Better analogue: human lung Tidal system, NOT circulatory Not a ventilation system, as thermal sink in soil acts as heat buffer. Thermal sink

27 What makes up a colony? Reproductives: Royal pair Alates Soldiers (2 morphs) Workers (2 morphs) Fungus Mound & nest 8-10 organ systems?

28 At what level can we recognise an organism? Organisms: Persist (protection, defence, feeding, movement etc ) Reproduce The organismal level of organisation is therefore the lowest hierarchical level which fulfils those requirements What is that level in, say, Homo, and Macrotermes? What is the lowest level of organisation that acts like an organism?

29 Organisational levels: Homo Entity Persist Reproduce Mitochondria X X Nucleus X X Cell X X Ovary X ( ) Heart X X Human body Therefore, trivially, human body is the level of organisation that acts like an organism

30 Organisational levels: Macrotermes Entity Persist Reproduce Mound / nest X Soldier X X Worker X X Reproductive (X) Fungus X ( ) Colony Therefore colony is the level of organisation that acts like an organism

31 MOLECULES Proto-Eukaryote Eukaryote cell α-proteobacterium Pre-cell Cell brain Organ mouse Body colony Colony POPULATIONS

32 Organisational levels of complexity Atoms Molecules Prokaryote cell Eukaryote cell Organ (somatic/ gametic) Body Colony Populations Metapopulations Communities Biotic (? Organismal ) level

33 Superorganism definition Examined in this way we seem to have two definitions of superorganism: 1. An organism made up of many other entities, which are themselves organisms 2. An organism made up of many other entities, which are now, or have been in the past, organisms (1) limits us to, say, dictyostelid slime moulds (2) includes almost everything There seems to be no logical justification for the concept superorganism as presently employed

34 A superorganism?

35 So analogy among multicellular organisms? Six multicellular origins: 1. Metazoa (animals) 2. Plantae (green plants) 3. Volvocaceae (green algae clade) 4. Phaeophyta (brown algae) 5. Rhodophyta (red algae) 6. Fungi Which is a fair analogy?

36 This seems to me to present a fairer analogy than Metazoa

37 Somatic cells (workers) Extra Cellular Matrix (nest) Gonidia (alates)

38 Value of somatic cells? [we] concluded that by pumping nutrients into the Extra Cellular Matrix to feed the gonidia, Volvox carteri somatic cells elevate the reproductive performance of the organism more than enough to provide a powerful selective advantage, despite the fact that they themselves have no reproductive potential whatsoever. Kirk (2003, Inter. Comp. Biol.) - This sounds familiar!

39 Multiple origins of germ and somatic lines Origin of clade ~ 75 MYA

40 So Difference between different permanent aggregations are differences in organisational complexity, not differences in kind Difficult to make comparisons between hierarchical levels except as rough analogies Candidate superorganisms (or metaorganisms ) do not qualify as their constituents parts are not organisms Almost all are, considered globally, colonial organisms, or more simply organisms

Unit 2: Characteristics of Living Things Lesson 18: From Cell To Organism

Name Unit 2: Characteristics of Living Things Lesson 18: From Cell To Organism Date Objective: Students will be able to compare organisms unique cells and cellular organization. Essential Questions: 1.