Coevolution of plant and insects (pollinators)

1. Coevolution of Plants and Insects
By
M. M. Mawtham
Ph.D. Scholar
Dept. of Agricultural Entomology
TNAU, Coimbatore

2. Coevolution
 Coevolution term coined by Charles Mode (1958)
 What is Coevolution?
‘Evolution of two or more evolutionary entities
brought about by reciprocal selective effects
between the entities’
(Ehrlich and Raven, 1964)

3. Ehrlich and Raven point out that:
 Reciprocal evolutionary relationship between
phytophagous insects and plants.
 Evolution of secondary plant substance critical in
angiosperm subgroups
 Evolution of secondary plant compounds and stepwise
evoltionary responses to these by phytophagous organisms
have clearly been the dominant factor in the evolution of
butterflies and other phytophagous groups
(Ehrlich and Raven, 1964)

4. The major developments
 Late Silurian–Middle
Devonian - origin of herbivory
 Late Pennsylvanian -
expansion of herbivory
 Permian-herbivore
colonization of new habitats
 End-Permian - global crisis;
 EarlyMesozoic-
rediversification of plants and
herbivores
 End-Cretaceous - effects on
extinction
 Biological effects of the
Paleocene–Eocene Thermal
Maximum (PETM)
 Mid-Mesozoic -long
proboscid pollinators; and
effect of the angiosperm
revolution on earlier pollinator
relationships.
(Labandeira, 2013)

5. A gallery of fossil plant–insect interactions representing the perspectives of
time interval, interaction type, preservational mode, and medium of
illustration.
Images (a)–(d) represent herbivory from Paleozoic (a, b), Mesozoic (c), Cenozoic
(d), (e) and (f) represent Mesozoic and Cenozoic pollination

6. Learning and cognition in insects
 Pavlovian Conditioning
 Repetition of trials (at least three trials with a 10-min
intertrial interval) induces a stable, long-lasting memory
(>7 days) that is insensitive to amnestic treatments and
requires translation and transcription.
 Operant Conditioning
 Pioneer work of Nobel-prize - Karl von Frisch
(Giurfa, 2015)

7. Cognitive revolution
Pavlovian olfactory conditioning of the proboscis extension
response (PER) in restrained honeybees

8. The challenge of host recognition
(Bruce, 2015)
coincidence detection mechanism

9. Neural Basis of a Pollinator’s Buffet: Olfactory
Specialization and Learning in Manduca sexta
(Riffell et al., 2013)

10. Herbivore–plant coevolution
Bursera aptera
Number of hosts attacked by
Blepharida species
Blepharida pallida
Geographic
localization of
selected areas
(Becerra, 2007)

11. Mutation
 Mutations are changes in the genetic sequence and they are
a main cause of diversity among organisms.
 Homeotic (Hox) protein mutation and macroevolution
of the insect
(Ronshaugen et al., 2004)
Evolution of trunk Hox gene expression patterns and sequence comparison of
arthropod Ubx proteins.

12. Insect Adaptation
 Structure and Function of Cytochrome P450S in Insect
Adaptation to Natural and Synthetic Toxins: Insights Gained
from Molecular Modeling (Schuler and Berenbaum, 2013).
 plant secondary metabolites have evolved as plant defence,
insects may overcome the defences by coevolving adaptations
such as cytochrome P450 monooxygenases (P450s) that
metabolize plant toxins.
 Mechanism
 Higher constitutive production of transcripts due primarily to
mutations in promotersequences.
 Higher inducible expression of transcripts due primarily to
mutations in trans –acting factors or their signaling cascades .
 Greater responsiveness to transcriptional inducers in food
sources and/or environment.

13. Types of Coevolution
 Specific coevolution
Changes in one species induce changes in the other
Either polygenic or gene for gene coevolution
 Concordant speciation
Speciation in one form causes speciation in another
 Diffuse coevolution
Reciprocal adaptation of a suite of species imposed
by another suite of species
Eg. Plants evolve defense against many herbivore
species
(Thompson, 1989)

14. Mutualism (+/+)
 Interaction between species that benefit both
participants
 The term ‘mutualism’ - Pierre van Beneden (l876)

15. Insect pollination
 Pollen from an anther stigma (fertilizing ovules)
 Angiosperms - bees and butterflies - Mid- Cretaceous
and into the Tertiary (Grimaldi and Engel, 2005).
CycadsHoney bee pollination

16. Pollination syndromes
 A pollination syndrome as a suite of floral traits, including
rewards, associated with the attraction and utilization of a
specific group of animals as pollinators.
 75 % (209/278) of the flowering plant species exhibit
specialization onto functional groups.
 Eg. Petunia
 Bee pollination- Petunia integrifolia
 Hawk moth pollination - Petunia axillaris
 Bird pollination - Petunia exserta
(Fenster et al., 2004)

17. Longer floral tubes and longer insect tongues
 In 1862, when Darwin examined this orchid, he predicted that a long-
tongued moth would be found that pollinated it; no moth with that
extreme length of tongue was known at the time.
Star orchid
(Angraecum sesquipedale)
Long-tongued moth
(Xanthopan morganii)
(Wasserthal, 2011)

18. Cheating in plant–pollinator coevolution
 Nonmutualistic interaction - no rewards
 Flowers that do not reward their pollinators must still
attract them to visit either by mimicking flowers that
do provide a reward, or by attracting the pollinator
through some other lure.
 Eg. Ophrys insectifera - Campsoscolia ciliate
 volatiles produced by the orchid - (omega-1)- hydroxy
acids and (omega-1)-oxo acids) are novel in plants
(Ayasse et al., 2003)

19. Titan arum Sweat bees
(Amorphophallus titanum) (F: Halictidae)
(Whitney and Glover, 2013)

20. Coevolution between yuccas and yucca moths
(Whitney and Glover, 2013)
Tegeticula sp.Yucca filamentosa

21. Fig and fig wasps
 900 species of figs all pollinated by Agaonidae
(Chalcidoidae) wasp
 Figs:
• Unique front design for entry of wasps
• Phenology of female flower receptivity and pollen
production in synchronise with wasp life cycle
• Seeds at different heights, some available to wasps,
some reserved

22.  Wasps
 Morphological adaptation including female body
adaptation for squeezing into fig, also pollen
receptacles
 Load and release pollen behaviors
 Specifically between fig species and wasp species
(Machado et al., 2005)

24. Pollinator Pollinator
characteristics
Typical flower types Example plants
Hummingbirds Long bills, highly developed
ability to perceive red, high
metabolic needs, ability to
hover.
Red or reddish flowers, long
broad tubes, often pendent or
horizontal, large nectar
rewards.
Honeysuckle, currants,
salmonberry,columbine
.
Bees, including
bumblebees,
honey bees and
solitary bees
Perception of bilateral
symmetry, blue and yellow
colors and ultraviolet light;
dexterity at manipulating plant
parts, ability to strongly vibrate
by buzzing,
need for both nectar and pollen.
Flowers with bilateral
symmetry, often in
shades of blue or yellow,
nectar guides in the ultraviolet
spectrum, flowers that require
dexterity to open, sometimes
bell-shaped flowers.
Lupines, clovers,
orchids, penstemons,
ericads (buzz
pollination).
Butterflies High nectar needs, require
sunlight for
flying, long tongues
Bright colors, often tubular
flowers, nectar
rewards.
Phlox, milkweed,
sunflower family.
Moths Often fly at night, sensitive to
fragrance, ability to hover.
White or pale flowers which
may open at night and close
during the day, releasing
fragrances, pendant or
horizontal flowers
Catchfly, stickseed,
wild tobacco.
Flies, including
mosquitoes
Attracted to odors (sometimes
unpleasantto humans),
generalists.
Generally open accessible
flowers, often releasing odors
flies find attractive.
Many composites,
sandworts, mustards,
Reprinted, lomatiums.
Pollinators and flower types

25. Abominable mystery
(Friedman, 2009)

26. Defence
 Coevolution between plants and herbivores occurs as a
reciprocal evolutionary interaction between a plant and
one.
 Defence mechanisms
 Physical (e.g. thick cuticle, trichomes and spines)
 Chemical (e.g. alkaloids, quinones, essential oils,
glycosides, calcium oxalate crystals and silicates)
 Temporal (e.g. early spring flowers)
(Eisner et al., 1998)

27. Coevolution between
Passiflora Heliconius
 Passiflora plants is the production of toxins (alkaloids
and glycosides) and this strategy is successful against
the vast majority of insects.
 Heliconius butterflies – have managed to overcome
this defence (Radhamani et al., 1995) .
Passiflora foetidaPassiflora adenopoda

28. Extrafloral nectaries
attract
Butterfly eggs PupaeStipules

29. Protection of plants by ants
Myrmecophytes Ant
(Acacia, Cecropia and Macaranga)
(Blatrix et al., 2009)
(Crematogaster borneensis)
(Petalomyrmex phylax)

30. Ant-mediated seed dispersal
(Giladi, 2006)
 Myrmecochory or seed dispersal by ants, is often regarded as
a diffuse mutualism between a guild of plants and a guild of
ants. myrmecochorous seeds is the presence of an elaiosome.