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?