The influence of mating systems on morphological and
physiological divergence in bats (Chiroptera)
Karen Acree, Jacqueline Ho, Harald Parzer, Mayté Ruiz
Evolution and Constraints
Why are some traits stable and others not?
Constraints – phenotypic space (directions in which evolution could lead) is diminished
InheritanceSelectionDevelopment (e.g. due to pleiotropic effects)
Design limits
(Arnold, 1992)
Evolution and Constraints
• By imposing or relaxing a constraint evolution could go into different directions
Evolution of Mating Systems
• Explained by the interface of sexual selection and ecological factors
• Reproductive success of ♂ is limited by the amount of ♀
♂ should monopolize as many ♀ as possible
• ♀ distribution depends on the distribution of key resources: scarce and not clumped or scarce and clumped
Scarce and clumped: polygamy
Scarce and not clumped: monogamy
(Emlen and Oring, 1977)
Evolution in Mating Systems
•Mating system could relax or impose a constraint: e.g. in polygamous species there is sexual dimorphism (overrides natural selection)
polygamybigger testes, smaller brain
Chiroptera (bats)
• High species diversity
• Phylogeny well studied
• Diverse mating systems
• Adaptive radiation in feeding habits
http://www.nationaltrust.org.ky/info/bats.html
Mating system Fruit-eaters
Larger brains
(♀) Monogamy?
Diet?
Pitnick et al 2006, Jones and MacLarnon 2004, Eisenberg and Wilson 1978
(1) Does diet in bats relate to their mating system?
Method: COMPARECollect information on the mating system and eating habits of several hundred species of chiroptera
- literature search
-standardized questionnaire to active field workers
Analyze data using the COMPARE software program
Martins 2004
www.skullsunlimited.com
Insectivore Frugivore
Diet and Morphology
Testing the effect of mating systems on basal stress levels and immune function
10 species were chosen:
5 monogamous
5 polygamous (Leks, mating aggregations/swarming)
Mating System and Physiology
Monogamous vs. Polygamous
• Lavia frons (Megadermitidae):African Yellow-winged bat
• Cardioderma cor (Megadermitidae): Heart-nosed bat/ African false vampire bat
• Saccopteryx leptura (Eballonuridae): lesser sac-winged bat
• Hipposideros beatus (Rhinolophidae): Benito roundleaf bat
• Rhinolophus sedulous (Rhinolophidae): lesser woolly horseshoe bat
• Hypsignathus monstrosus (Pteropodidae): African hammerhead bat
• Myotis sodalis (Vespertilionidae): Indiana Bat
• Myotis daubentoni (Vespertilionidae): water bat/ Daubenton’s bat
• Miniopterus schreibersii (Vespertilionidae): Schreibers's long-fingered bat
• Balantiopteryx plicata (Emballonuridae): gray sac-winged bat
www.cbmall-gateway.com/bats/heartnosed_bat.html
http://animaldiversity.ummz.umich.edu
http://animaldiversity.ummz.umich.edu
http://filin.vn.ua/image/bat/s.leptura.jpg
www.ecologyasia.com/images-k-z/lesser-woolly-horseshoe_00821.jpg
http://animaldiversity.ummz.umich.edu
http://animaldiversity.ummz.umich.edu
http://animaldiversity.ummz.umich.edu
http://animaldiversity.ummz.umich.edu
http://www.worlddeer.org/britishbats/daubentons.html
(2) Do mating systems affect basal stress
levels?
CRH and AVP
Stress
Hypothalamus (PVN)
Anterior pituitary
Adrenal gland
Cortisol
Immune Cells
Hippocampus
ACTH
Raison & Miller (2003)
Cortisol
-
-
-
-
+
+
+
Monogamous ♂♀ Polygamous ♂♀
Non-breeding
season
Breeding season [CORT ][CORT ]
[CORT ][CORT ]
Take blood samples and perform enzyme immunoassays (EIA)
Determine ∆ [CORT] (from non-breeding to breeding seasons)
(3) Do differences in mating system affect immune
responses?
• Multiple matings may incur a cost to females • If diet is in fact correlated with mating system,
fruit may have a positive association with immunity
http://www.enature.com/fieldguides/enlarged.asp?imageID=18884
Elucidate causes by testing both reproductive and non-reproductive females.
Monogamy and immune function
Martin et al 2004, Lampe 1999, Nantz et al 2006
Method: Measure cell-mediated immunity
• Delayed-type hypersensitivity
• Inject with phytohaemagglutinin– prime– Measure swelling
http://www.nature-shetland.co.uk/naturelatest/pics/nat%20the%20bat.jpg
Concluding remarks
Thus, new phenotypic traits can emerge when the constraint of polygamy is lifted. These new traits need not directly relate to monogamy.
This allows us to elucidate whether mating system constraints directionally influence morphological and physiological change.
COMPARE will show if a relationship exists between mating system and feeding habits, which may then lead to morphological differences.
Stress and immune measures will demonstrate whether mating systems induce physiological changes.
Questions?