In this order, Odonata's evolution of sexual traits is mistaken as a result of male-male completion. But females do contribute these traits, very evidently in Damselflies due to the harrasment they face. This presentation is about the evolution and ethology of male avoidance by females color polymorphism, its inheritance, and consequences.
2. Polymorphism
Presence of different morphological forms
Multiple benefits
Division of labour
Predator avoidance
Sexual dimorphism – attract mate
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3. Sex limited polymorphism
Either male or female are polymorphic
Polymorphic male: male-male competition
Polymorphic female
Against visual hunting predator
Sexual harassment by males
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8. Female harassment
Male with strong claspers
Repeated copulation- damage female’s
wings
reproductive tract
reduce fitness
Dominant males remove sperm and egg fertilization results from
the female reproductive tract and re-copulate
(Fleming, 2019)
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9. Female strategies to overcome this….
Evolved monogamy (Fincke, 1986)
Pretend laying eggs even if she is not (Aguilar, 2015)
Shift in the activity periods compared to males (Pérez et al., 2021)
Allows sneaky males (Fleming, 2019)
Multiple colour morphs
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10. Multiple female colour morphs
Males easily recognize females - similar coloration
Distracted & confused - multiple phenotypes or colour morphs
coexist
Evolution of male mimicry – male like females - andromorphs
Escape from male harassment
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Learning by male ???
11. Ischnura elegans
Reproductive season: May – September
(↑ in June)
Scramble mate competition
Males are best at locating females
Females - highest reproductive success
Male mate competition – intense
Female suffer high harassment
Half of male in a population never
succeed in mating
Monomorphic male and 3 coloured female
morphs
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(Hammers and Gossum, 2008)
12. Colour polymorphism in
Ischnura elegans
3 coloured female morphs
Androchrome – male like female
– similar colouration & body melanin patterning
Gynochrome – ordinary female – 2 types
Infuscans - body melanin patterning similar to male
Infuscans-obsolete –lack black numeral stripes on thorax
Extent of male mimicry: Androchrome > infuscans > Infuscans-obsolete
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(Hammers and Gossum, 2008)
13. Androchrome frequency:
27-76%
↑sed towards North &
West
Male : female
male density
↑ Fandromorph - ↓ sed temp.
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(Hammers and Gossum, 2008)
W
30 populations – different water body
June: 16.0-16.5℃, 16.5-17.0℃, 17.0-17.5℃, 17.5-18.0℃
NS fandromorph
15. Andromorphs escapes from both conspecific
and heterospecific mating and thus harassment
(Svensson et al., 2007)
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Male like female suffer less from harassment
16. Stable morph differences in mating
rates across years and populations
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(Gosden & Svensson, 2009)
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What if these population are with low density of
andromorph which cannot be detected by males ?
Do males switch their preference for andromorphs
if their density increase in populations ?
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2
18. Male clasping damage
Non-androchromes: ↑sed number
of male claspings with increasing
density
Androchromes lower sensitivity to
male clasping as their density
increases
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(Gosden & Svensson, 2009)
Circles: androchromes
Downward triangles: infuscans triangles
Forward triangles: infuscans-obsolete
19. Androchromes were not preferred by males
even if they are the majority morph
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infuscans-obsolete
Population with 85% androchromes
Males behaved indiscriminately and did not prefer the commonest androchromes
Diagonals indicates the expected proportion females mate to their population frequency
Points below the diagonal for female frequencies below 50% and above the diagonal
Androchromes infuscans
(Rivera and Guillen, 2007)
Androchrome mating is not density dependent
20. What if these colour morphs are
just age dependent colouration ???
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21. Inheritance of female polymorphism
in Ischnura graellsii
Polymorphism begins at teneral stage
- genetically distinct female types
- not just age related morphs
Inheritance – sex linked expression
-one autosomal locus
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(Cordero, 1990)
22. Laboratory matings – F1
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(Cordero, 1990)
A female produce – either of 1,2 or all three morphs
2 phenotypes – 1:1 or 3:1
3 phenotypes – 1:1 or 2:1:1 (A:I:O)
Males- 6 genotypes one phenotype
A- recessive
I- heterozygotes
O- dominant
24. Ancestrally FM(H), P = 81%
All FP(T) - common ancestor FP(T),
derived from FP(D)
-high mating duration – Third morph
Two evolutionary transitions occurred
FM(H) → FP(D) → FM(A) & FM(T)
convergent evolution of 2 morphs
- intensity harassment & need of FP
Male mimicry and FP - derived traits
and not ancestral
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(Blow et al., 2021)
- monomorphic
- heteromorphic / gynomorphic
- dimorphic
- trimorphic
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All island-endemic species are monomorphic – so the ancestors
Species distributed widely - either FP(D) or FP(T)- adaptations for survival
P(FP) ↑* ~5% with its geographic size range of 1 x106 km2
(Blow et al., 2021)
FP is a trait having ancestry of years together
Neither just a random morph nor a age dependent colouration
A trait regulated by recessive genes
Tri-allelic single autosomal locus regulating the inheritance
26. Why nature should support such a female
morph which even avoid the transfer its gene
to generations ??
Only Male harassment ??
Other fitness benefits ??
Does environment has any role to play in this
hide and seek of polymorphism ???
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27. Androchromes need not to hide
(Castillo- Pérez et al., 2021)
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Clear andromorphs – high temperature tolerant
Darker gynomorphs – heats up quickly, activity seizes at
high temp. where males are active
Adult male Andromorph Gynomorph
Ischnura denticollis
28. High temperature tolerance
Clear females – andromorphs
Dark females – gynomorphs
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(Castillo-Pérez et al., 2021)
(Cooper, 2008)
29. High elevation survival
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High-elevation populations - sexually monomorphic and red
low-elevation - sexually dimorphic with green females
(Cooper, 2008)
Megalagrion calliphya
Males
Andromorphs
30. Mean Anti oxidant breakdown time
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Andromorphs break down hydrogen peroxide more effectively than gynomorphs
Red pigmentation function on antioxidant & protects from UV damage
(Cooper, 2008)
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Evolution of male mimics gains
multiple benefits apart from “escape”
What about males? Does he bother
about these female games” ??
32. Males’ perspective
Q1-Andromorph
Q2,Q3- heteromorphs
A, B, C- male criteria's
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(Fincke, 2004)
Vm- cost of miss
Um- cost of false alarm
Umdis- cost on conspecific males
OSR – Operational Sex Ratio
Cost of miss – selective force - evolve male learning
At the cost of false alarm – wastage of sperms, time, energy
physical damage
Other side of the coin- FP in Males’
perspective
33. Female are the decision makers-playing
with their detectability
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(Fincke, 2004)
Females are the dictators of male fitness
34. Summery
Damselflies - polymorphic females
Evolved to overcome sexual harassment by males
FP are not density dependant
Polymorphic female are distinct phenotypes – not just age
related morphs
It’s a derived trait, not ancestral
Andromorphs – high fitness compared to gynomorphs
Derives multiple benefits
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35. Conclusion
Damsels- assumed as taxa whose females have reduced or no
control of mating and fertilization decisions
Evolution and maintenance of secondary sexual traits is mainly
driven via male–male competition
Contrary to this, “dull coloured” gynomorphic female face
harassment, hence have evolved bright andromorphs
How exactly this number is maintained over generation- yet to be
solved by further studies
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